Acta Physica Sinica
Citation Search Quick Search

ISSN 1000-3290
CN 11-1958/O4
Semimonthly
About
   » About APS
   » Editorial Board
   » SCI IF
   » Staff
   » Contact
Browse APS
   » Accepts
   » In Press
   » Current Issue
   » Past Issues
   » View by Fields
   » Top Downloaded
   » Sci Top Cited
Authors
   » Submit an Article
   » Manuscript Tracking
   » Call for Papers
   » Scope
   » Instruction for Authors
   » Copyright Agreement
   » Templates
   » Author FAQs
   » PACS
Referees
   » Review Policy
   » Referee Login
   » Referee FAQs
   » Editor in Chief Login
   » Office Login
Links
   »
HighLights More»   
Research progress of hybrid cavity-magnon systems
Shen Rui-Chang, Zhang Guo-Qiang, Wang Yi-Pu, You Jian-Qiang
Acta Physica Sinica, 2019, 68 (23): 230305
Electrical transport measurement system in pulsed high magnetic field based on rotation sample rod
Liu Qin-Ying, Wang Jun-Feng, Zuo Hua-Kun, Yang Ming, Han Xiao-Tao
Acta Physica Sinica, 2019, 68 (23): 230701
Temperature measurement method of high temperature and high pressure flow field based on wavelength modulation spectroscopy technology
Zhang Bu-Qiang, Xu Zhen-Yu, Liu Jian-Guo, Yao Lu, Ruan Jun, Hu Jia-Yi, Xia Hui-Hui, Nie Wei, Yuan Feng, Kan Rui-Feng
Acta Physica Sinica, 2019, 68 (23): 233301
Current Issue Accepts In Press Earlier Issues Top Downloaded SCI Top Cited
  Acta Physica Sinica--2019, 68 (23)   Published: 05 December 2019
Select | Export to EndNote
INVITED REVIEW

Research progress of hybrid cavity-magnon systems Hot!

Shen Rui-Chang, Zhang Guo-Qiang, Wang Yi-Pu, You Jian-Qiang
Acta Physica Sinica. 2019, 68 (23): 230305 doi: 10.7498/aps.68.20191608
Full Text: [PDF 4340 KB] Download:(131)
Show Abstract
Recently, the hybrid cavity-magnon system has attracted considerable interest. Owing to the good tunability of magnons, it is promising to use the magnons as a core to implement a hybrid quantum platform for transferring information among different quantum systems. In this article, we first briefly review the cavity magnonic systems and clarify the coupling mechanism between magnons and microwave photons. Then, we introduce the latest research progress in the aspects of nonlinearity and pseudo-Hermiticity, including the bistability of cavity magnon polaritons, observation of the second-order exceptional point in a PT-symmetric hybrid cavity-magnon system, and the pseudo-Hermiticity with a third-order exceptional point.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

Semi-closed T-shaped-disk waveguide filter based on surface-plasmon-induced transparency

Chen Ying, Xie Jin-Chao, Zhou Xin-De, Zhang Can, Yang Hui, Li Shao-Hua
Acta Physica Sinica. 2019, 68 (23): 237301 doi: 10.7498/aps.68.20191068
Full Text: [PDF 1163 KB] Download:(26)
Show Abstract
Filter is the core communication device in optical integrated chip. In recent years, plasma-induced transparency in surface plasmon (SPP) subwavelength waveguide photonic deviceshas become a research hotspot in the field of nano optics. The plasmon-induced transparency (PIT) is a phenomenon that the original absorption region produces a sharp transparent window due to the interaction among different resonant modes of SPPs, therefore, a higher resolution and quality factor surface plasmons can be obtained by using this feature to design a metal-medium-metal (MIM) waveguide structure filter. However, due to the Ohmic loss caused by metal parts, further research is needed on how to effectively improve transmission efficiency and achieve better frequency selection and filtering effect while reducing filter bandwidth in MIM waveguide filter. Based on the transmission and coupling characteristics of SPPs, an MIM waveguide filter with semi-closed T-waveguide side coupled disc cavity is proposed.Its transmission characteristics are studied by using the finite element method. The results show that a narrow-band transmission peak based on plasma-induced transparency appears in the transmission spectrum. Through theoretical analysis and mode field distribution, the physical mechanism of generating the PIT transparent peak and valley values on both sides is effectively explained. Compared with the traditional straight waveguide structure, the curved waveguide structure can generate the bilateral coupling effect, which can make resonant interaction stronger. Meanwhile, the numerical study shows that the approximately linear adjustment of filter wavelength can be achieved by changing the length of branches, the radius of the disk cavity and the refractive index of the medium in the cavity through external modulation. Further, the gain medium is embedded in the disk cavity, which enhances its local ability to emit light, strengthens the mode resonance effect, and realizes the compression filter pass-band bandwidth while effectively improving the structural transmittance, compared with similar filters. The research results provide an effective theoretical reference for designing the high resolution narrowband filter.

Electron transport properties of isomeric quinoline molecule junction sandwiched between graphene nanoribbon electrodes

Zuo Min, Liao Wen-Hu, Wu Dan, Lin Li-E
Acta Physica Sinica. 2019, 68 (23): 237302 doi: 10.7498/aps.68.20191154
Full Text: [PDF 1239 KB] Download:(32)
Show Abstract
Since graphene was successfully obtained in the end of 2004, the research on graphene and relevant devices has attracted extensive attention. The armchair- and zigzag-edge graphene nanoribbons, as the building blocks, are often used to design the graphene-based molecular electronic devices. Quinoline, an important intermediate between metallurgical dyes and polymers, is an organic conjugated small molecule which is simple in structure and easy to synthesize and modify the chemical structure, and quinoline has become one of the research focuses in the field of molecular electronic devices in recent years. From the physical point of view, the transport properties of the isomeric quinoline molecular electronic devices connected with graphene nanoribbon electrodes can provide a theoretical basis for designing and manufacturing molecular electronic devices with excellent performance. Based on the first-principles calculation method combining the density functional theory and non-equilibrium Green's function, this paper systematically investigates the transport properties of the carbon-linked isomeric quinoline molecule electronic devices sandwiched between the graphene nanoribbon electrodes. The obtained results show that the device current presents a linear change in a bias voltage range [-0.3 V, +0.3 V], the current decreases with the increase of the absolute bias voltage, separately, in a range of [+0.5 V, +0.8 V] and [-0.4 V, -0.9 V], demonstrating a strong negative differential resistance effect. On the other hand, the interesting negative differential resistance effect is remained when there is an angle between the quinoline molecular plane and the graphene nanoribbon electrode; the current of the device is found to be independent of the rotation direction of quinoline molecule in the central region; the current of the device should be forbidden when the quinoline molecule plane is rotated to a direction vertical to the graphene nanoribbon electrodes. The obtained results can provide a theoretical basis for designing and manufacturing the molecular switches and negative differential resistance devices based on isomeric quinoline molecular electronic devices.

First-principles study of magnetic properties of alkali metals and alkaline earth metals doped two-dimensional GaN materials

Chen Guo-Xiang, Fan Xiao-Bo, Li Si-Qi, Zhang Jian-Min
Acta Physica Sinica. 2019, 68 (23): 237303 doi: 10.7498/aps.68.20191246
Full Text: [PDF 1647 KB] Download:(143)
Show Abstract
We systematically study the electronic structure and magnetic properties of alkali metals (Li, Na, K and Rb) and alkaline earth metals (Be, Mg and Sr) doped two-dimensional GaN monolayers using the first-principles calculations based on density functional theory. The results show that Be atom is located in the plane of the GaN monolayer, and the other doped atoms reside slightly above the plane. It is found that doping is easier to achieve under the N-rich condition. The total magnetic moment of the alkali metals doped system and the alkaline earth metals doped system are 2μB and 1μB, respectively, which are presented mainly by the spin-polarized holes of the nearest N atoms of the impurity atoms. The band structures indicate that the four alkali metal atoms doped systems are magnetic semiconductors, and the three alkaline earth metal doped systems are all semi-metallic. For a double M-doped GaN monolayer system, there is a long-range ferromagnetic coupling in the seven elements doped systems, which are realized by the hole-mediated p-p hybrid interaction. The Heisenberg mean field model is used to estimate the Curie temperature. It is found that the long-range ferromagnetic coupling states of Li, Be, Mg and Sr are existent at higher than room temperature, indicating that the four atom-doped two-dimensional GaN monolayers are very good candidates for the room temperature ferromagnetic candidate materials. The alkali metals and alkaline earth metals doped two-dimensional GaN monolayers are expected to play an important role in the studying of spintronics.

Optically modulated electromechanical coupling properties of single GaN nanobelt based on conductive atomic force microscopy

Deng Chang-Fa, Yan Shao-An, Wang Dong, Peng Jin-Feng, Zheng Xue-Jun
Acta Physica Sinica. 2019, 68 (23): 237304 doi: 10.7498/aps.68.20191097
Full Text: [PDF 1101 KB] Download:(20)
Show Abstract
Gallium nitride (GaN) nanobelt with a quasi-one-dimensional structure possesses good piezoelectric and photoelectric properties. In this paper, the electromechanical coupling properties of single GaN nanobelt under optical modulation are studied by conductive atomic force microscope. The GaN nanobelts with good crystallization are prepared by the chemical vapor deposition method, then they are ultrasonically dispersed on a highly oriented pyrolysis graphite substrate. The conductive probe is used as a microelectrode to construct the two-terminal piezoelectric device based on a single GaN nanobelt, which has good electromechanical coupling performance. By changing the loading force of the probe and introducing an external light source to regulate the current transport properties of GaN nanobelt, the coupling between mechanical and semiconducting properties under light modulating is studied. It is found that the coupling between mechanical and semiconducting performance of the single GaN nanobelt can be effectively modulated by an external light source, and the electromechanical switch ratio of the single GaN nanobelt increases obviously in the presence of light. With the loading force increasing, the current response of the single GaN nanobelt increases but the rectification characteristics decrease. Finally, the experimental results are explained by the piezoelectric electronics and photoconductivity theory. This work is expected to provide a scientific basis for the performance modulation of nano-piezoelectric optoelectronic devices based on low-dimensional GaN nanomaterials.

Fluorescence enhancement of monolayer MoS2 in plasmonic resonator

Meng Fan, Hu Jin-Hua, Wang Hui, Zou Ge-Yin, Cui Jian-Gong, Zhao Yue
Acta Physica Sinica. 2019, 68 (23): 237801 doi: 10.7498/aps.68.20191121
Full Text: [PDF 1065 KB] Download:(46)
Show Abstract
Molybdenum disulfide (MoS2), as a layered transition metal chalcogenide, plays an important role in fields of photonics and photoelectronics. Here, a coupled system consisting of monlayer MoS2 and nano-resonator is designed and implemented. The photoluminescence (PL) spectrum of the MoS2 is coupled with the resonant mode of plasmonic bowtie resonator, thus achieving an optimal PL enhancement condition. Based on the analysis of theoretical model and experimental data, the spontaneous emission rate can be controlled by the Purcell effect, and the broadband enhanced spectrum is obtained in which its peak value increases 9.5 times and bandwidth is 100 nm . Meanwhile, the enhanced PL intensity also satisfies the cosine function relation between the polarization angle of the exciting light and that of the detecting light, which proves that the resonance mode comes from the electric field dipole in the resonator. This study provides the feasibility of studying the enhancement of light-matter interaction in an MoS2-plasmonic resonator coupled structure, which opens up a new route to improving the emission and detection efficiency of MoS2-based photonic devices in future.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Terahertz vortex beam generation based on reflective metasurface

Li Xiao-Nan, Zhou Lu, Zhao Guo-Zhong
Acta Physica Sinica. 2019, 68 (23): 238101 doi: 10.7498/aps.68.20191055
Full Text: [PDF 1145 KB] Download:(33)
Show Abstract
The electromagnetic wave with spiral wavefront is a vortex beam carrying orbital angular momentum. The phase singularity of the vortex beam has special applications in the fields of particle manipulation and communication. In this paper, a terahertz (THz) wide-band vortex beam generator based on reflective metasurface is proposed and simulated. The device consists of a metasurface-dielectric-metal three-layer structure, and the top layer is a metasurface composed of two orthogonal I-shaped metal structural units. The intermediate layer of polyimide medium, and the bottom layer is of metal as a reflecting plate. The CST microwave studio is used to simulate the reflection performance of unit cell. The structure parameters are optimized to obtain the better performance. A set of optimed structure parameters is determined. According to the phase principle of Pancharatnam-Berry (P-B), by rotating the angle of the top-layer I-type metal structure, the reflection amplitudes of the unit cell structure at different rotation angles are required to approximately equal while the phase changes linearly with rotation angle and reaches a range of 2lπ for the topological charge number l. These cell structures are arranged according to the phase principle mentioned above. The metasurfaces of different topological charge numbers are designed to generate the corresponding vortex beams. In this paper, the metasurfaces with topological charge numbers 1 and 2 are designed. The reflection amplitude and phase of the circularly polarized THz beam incident vertically on the metasurface are simulated by using CST microwave studio. The simulation results show that in a frequency range of 0.8-1.4 THz, the metasurface can convert the circularly polarized terahertz beam into a vortex beam with a different topological charge number. In addition, in order to illustrate that the metasurface designed can produce a higher topological charge number of vortex beam, a metasurface with a topological charge number of 3 is designed as an example. The reflection amplitude and phase of the circularly polarized THz beam at a frequency of 1.1 THz is simulated. The results show that the designed metasurface can produce a vortex beam with a topological charge number of 3. The higher topological charges of vortex beam can also be generated according to the corresponding phase arrangement. The device has a relatively wide operating bandwidth, simple structure, high conversion efficiency, and has the potential application in terahertz vortex beam generation.

Application of the proposed optimized recursive variational mode decomposition in nonlinear decomposition

Xu Zi-Fei, Yue Min-Nan, Li Chun
Acta Physica Sinica. 2019, 68 (23): 238401 doi: 10.7498/aps.68.20191005
Full Text: [PDF 5958 KB] Download:(23)
Show Abstract
Variational mode decomposition can improve traditional recursive algorithms, such as empirical mode decomposition, resulting modal aliasing and endpoint effects, but it has a significant influence on signal decomposition accuracy due to its pre-set parameters. The frequency corresponding to the peak value of the target signal power spectrum is proposed to initialize the center frequency required for the variational mode decomposition. The empirical mode decomposition and recursive model is used to improve the variational mode decomposition into the recursive mode algorithm based on the energy cutoff method. The group optimization algorithm optimally takes the penalty factor with bandwidth constraint ability to form an optimized recursive variational mode decomposition. By comparing with and analyzing empirical mode decomposition, integrating empirical mode decomposition and optimizing the computational accuracy of recursive variational mode decomposition in decomposing signals; studying traditional variational mode decomposition and optimizing recursive variational mode decomposition in dealing with actual vibration signals calculating rate, the results are obtained, showing that the optimized recursive variational mode decomposition has the highest accuracy when dealing with the target signal, and the correlation with the original component is 99.9%. Comparing with the integrated empirical mode decomposition, the signal can be decomposed into different frequency bands from low to high, and the physical meaning is clearer. No false modality is generated. When the actual nonlinear signal is processed, the optimized recursive variational mode decomposition does not need to preset the number of decomposition modes, and the calculation rate is 12.5%-18.5% higher than thay of the traditional variational mode decomposition.

Design of novel memristor-based neuromorphic circuit and its application in classical conditioning

Xu Wei, Wang Yu-Qi, Li Yue-Feng, Gao Fei, Zhang Miao-Cheng, Lian Xiao-Juan, Wan Xiang, Xiao Jian, Tong Yi
Acta Physica Sinica. 2019, 68 (23): 238501 doi: 10.7498/aps.68.20191023
Full Text: [PDF 1188 KB] Download:(22)
Show Abstract
Inspired by the working mechanism of human brain, the artificial neural network attracts great interest for its capability of parallel processing, which is favored by big data task. However, the electronic synapse based on CMOS neural network needs at least ten transistors to realize one biological synaptic function. So, CMOS-based neural network exhibits obvious weakness in speed, power consumption, circuit area and resource utilization and so on, compared with biological synapses. Therefore, how to build neuromorphic circuits and realize biological functions by constructing electronic synapses with low power consumption and high integration density have become the key points for human to realize brain-like computing system.
Memristors, as the fourth basic component, is a two-terminal nonlinear device possessing nonlinear conductance that can be tuned continuously. For that special characteristic, it is very similar to biological synapse whose connection strength can be adjusted continuously. In this article, first of all, we study the electrical characteristic of the Cu/MXene/SiO2/W memristor. When applying a positive DC sweeping voltage to the Cu electrode, the Cu electrode is oxidized, generating Cu2+. The generated Cu2+ in function layer tends tomove towards the bottom electrode under the action of electric field. Near the bottom electrode the Cu2+ moving from top electrode are reduced, generating a conductive Cu atom. With Cu atoms accumulating and extending from bottom electrode to top electrode, the memristor is gradually converted from the initial high resistance state (HRS) into the low resistance state (LRS). Secondly, combining with HP model of memristor, we utilize Verilog A language to simulate memristor in the experiment we conducted. Subsequently, we successfully construct the artificial synaptic unit and design the weight differential circuit with self-feedback branch. In the above circuit, we successfully implementa classical “Pavlov's dog” experiment. By applying the sinusoidal signal and pulse signal to the synaptic unit for testing and training it, respectively, the circuit realizes the convention between the conditions that unconditioned stimulus producing unconditioned response to conditioned stimulus producing conditions response.
This work takes memristor as a center, through modelling the electrical characteristic of Cu/MXene/ SiO2/W device, we construct a neuromorphic circuit with weight differential branch andself-feedback branch, successfully simulate the classical learning behavior of biological synapses, and realizes the whole process of biologically conditioned reflex, which is illustrated in detail in the experiment on “Pavlov's dog”. The results will provide effective guidance forconstructing a large scale and high density neuromorphic circuitbased on memristor, thus promoting the realization of brain-like computation in the future.

Atmospheric neutron single event effect in 65 nm microcontroller units by using CSNS-BL09

Hu Zhi-Liang, Yang Wei-Tao, Li Yong-Hong, Li Yang, He Chao-Hui, Wang Song-Lin, Zhou Bin, Yu Quan-Zhi, He Huan, Xie Fei, Bai Yu-Rong, Liang Tian-Jiao
Acta Physica Sinica. 2019, 68 (23): 238502 doi: 10.7498/aps.68.20191196
Full Text: [PDF 1098 KB] Download:(15)
Show Abstract
The 65 nm-microcontroller units (MCUs) are being widely used in critical terrestrial tests, and the risk from atmospheric neutron becomes more and more serious. The spallation neutron source contains broad energy spectrum, which is different from the mono-energetic neutron sources, and is the most ideal irradiation source for atmospheric neutron single event effect (SEE). Benefiting from China Spallation Neutron Source (CSNS), the atmospheric neutron SEE in 65 nm-MCUs is tested for the first time at the CSNS 9th beam line in China. The beam line is locatedin the 46° direction along the proton hitting the target, and the neutron spectrum is achieved to range from meV to 1.6 GeV. The test is conducted in two conditions in order to investigate the influence of thermal neutron. One is that the thermal neutrons are shielded with a 2-mm-thick cadmium slat at the beam ejection hole, and the other is not. The detected effects are single bit upset (SBU) events. 16 SBU events are detected when 5.3363×1017 protons hit the tungsten target without the thermal neutron, and 63 SBU events are recorded in the condition of 7.2131×1017 protons striking the target and thermal neutrons included. Comparing with the high energy neutron (>1 MeV), the SBU events caused by thermal neutron contribute about 65% of the number of total upset events. The test results preliminarily illustrate that the thermal neutrons dominate the 65 nm MCU reliability.

A symbolized time series network based on seasonal-trend-loess method

Wang Li-Na, Cheng Yuan-Yuan, Zang Chen-Rui
Acta Physica Sinica. 2019, 68 (23): 238901 doi: 10.7498/aps.68.20190794
Full Text: [PDF 1679 KB] Download:(27)
Show Abstract
Modeling the time series complex network provides a new perspective for analyzing the time series. Some classical algorithms neglect the unidirectionality of the time and the difference in correlation between primitives. While the symbolized time series network can construct the network on a controlled scale and can construct the weighted directed network which is closer to reality. Combined with the seasonal-trend-loess method and the symbolized transformation of the periodic time series, a time series network construction method is proposed. Both the state of a single data value and the long-term trend of the time series are considered in our symbolized time series network. The symbolic modes are used as nodes, and the edges are defined according to the adjacent transformation relationship between nodes. The direction and the weight of the edges are determined according to the conversion direction and the conversion frequency. Then, the directed weighted network is established. The air passenger throughput time series and the Internet traffic time series are used as the experimental data respectively. The topological features of these two time series networks are obviously different. Furthermore, to mine the essential laws of time series data, the empirical analysis of the time series of mobile communication voices is carried out. Our work enriches the research results of time series networks.
REVIEW

Review of charge deposition characteristics and trap parameters of dielectric in space electron radiation environment

Li Guo-Chang, Li Sheng-Tao
Acta Physica Sinica. 2019, 68 (23): 239401 doi: 10.7498/aps.68.20191252
Full Text: [PDF 1189 KB] Download:(48)
Show Abstract
Charging and discharging characteristics of dielectric in space electron radiation environment are closely related to the surface charge exchange process and internal charge transfer process. Surface or internal charge movement of dielectric depends largely on the microscopic characteristics of the material, and space charge and trap are important parameters reflecting the microscopic characteristics of dielectric. In this work, the formation, mechanism, measurement method, existing problems and research status of space charge and trap in insulation material in electronic radiation environment are reviewed. Firstly, the interaction mechanism between incident electron and dielectric material and the formation of deposition charge are briefly introduced. The advantages and disadvantages of radiation-induced conductance model and electron-hole pair generation/recombination model are analyzed. The classical electro-acoustic pulse method (PEA) and “short circuit PEA” and “open circuit PEA” which are suitable for space charge measurement under electron beam radiation are compared with each other and analyzed, and further, the main technical difficulties in designing PEA device under electron beam radiation are reviewed. Secondly, the methods of extracting trap parameters, including thermal stimulation current method, surface potential decay method, space charge decay method are compared with each other.
It is pointed out that the method of injecting the electrons and the method of measuring the surface potential in the same vacuum environment are more suitable for measuring the trap parameters of space dielectric materials. Finally, the scientific problems that need solving in space insulation are prospected from the aspects of theoretical model, parameter characterization and measurement technology.
GENERAL

Charging effect of polymer thin film under irradiation of high-energy transmission electron beam

Huo Zhi-Sheng, Pu Hong-Bin, Li Wei-Qin
Acta Physica Sinica. 2019, 68 (23): 230201 doi: 10.7498/aps.68.20191112
Full Text: [PDF 1148 KB] Download:(44)
Show Abstract
The serious charging effect of polymer film with a thickness of the order of microns under the radiation of high-energy transmission electron beam, on the reliability of the micro-nano electronic device in electron microscopy detection is investigated. The charging effect of the polymer film is numerically calculated in this paper. The scattering process is simulated by the Monte Carlo method. The elastic scattering is calculated with the Rutherford scattering model. The inelastic scattering is simulated with the fast secondary electron (SE) model and the Penn model. The transport, the capture, and the recombination process of the charges are treated with the finite difference method. The fourth-order Runge-Kutta method is used to solve the trajectory of the emitted SEs. The dynamic distributions of the net charge, the built-in electric field, the surface emission current, and the transmission current are investigated, and the influence of the film thickness and the beam energy on the charging characteristics are analyzed. The results show that due to the emission of electrons near the sample surface, the distribution of the net charge in the sample is first positive and then negative along the incident direction. In addition, under the irradiation,higher charge quantity is deposited in the sample, and the net charge density increases gradually. However, with long-time irradiation, the deposited electrons transport to the surface under the action of built-in electric field which reduces the surface net charge density. Therefore the net charge density tends to a stable value. The space potential is positive in the surface and negative inside the sample. Therefore some emitted SEs return to the surface, resulting in the electron beam-induced current. With the irradiation, the positive surface potential increases and tends to a stable value. Hence the actual surface emission current decreases to a stable value and the sample current increases to a stable value. The sample current remains unchanged due to the weak charging strength. Increasing the film thickness leads the transient time to increase, which contributes to the decline of the surface potential and the increase of the actual emission currentand sample current. The increase of the beam energy causes the transmission current to increase and the sample current to decrease.
In addition, it reduces the positive surface potential and the actual surface emission current accordingly. The results conduce to the decrease of the charging effect of the polymer film under the radiation of high-energy electron beam in the electron microscopy.

General resource theory of quantum coherence in multipartite system

Liu Feng, Gao Dong-Mei, Cai Xiao-Qiu
Acta Physica Sinica. 2019, 68 (23): 230301 doi: 10.7498/aps.68.20190966
Full Text: [PDF 896 KB] Download:(46)
Show Abstract
The theory of quantum coherence is an important kind of quantum resource theory, and its free operations are various kinds of incoherent operations. In the single-system coherence resource theory, the maximally coherent state is the most important quantum resource state, and it can turn into a quantum state of any other pure state. However, the situation is quite different from multipartite quantum systems: not only does no-go theorem forbidding the existence of a unique maximally coherent state exist there, but almost all pure multipartite coherent states are incomparable (i.e., some incoherent operation transformations among them are almost never possible). In order to cope with this problem, we consider general coherent resource theories in which we relax the traditional incoherent operations to operations that do not create coherence. Specifically, we consider two possible theories, depending on whether resources correspond to bipartite coherence or genuinely multipartite coherent states (each subsystem is coherent): one is the theory in which bipartite coherence states are considered as a resource and the free operations are bipartite incoherent preservation and the other is the theory that involves genuinely multipartite coherent states and fully incoherent operations. These ideas come from the research by Contreras-Tejada et al. (Phys. Rev. Lett. 122 120503), where the alternative entanglement resource theories were considered through relaxing the class of local operations and classical communication (LOCC) to operations that do not create entanglement, and they considered two possible theories depending on whether resources correspond to the multipartite entangled or genuinely multipartite entangled (GME) states. Furthermore, we show that there exists meaningful partial order (i.e. each pure state is transformable to a more weakly coherent pure state) in these two theory frames. Finally, we prove that the genuine multipartite coherent resource theory has a unique maximally coherent state (i.e. it can be transformed into any other state by the allowed free operations). Our results cover a wide class of coherent resource theories due to the free operations we introduced, and the discussion is solidified by important examples, such as entanglement, superposition, asymmetry, et al. And, how to establish the relations between these two kinds of multipartite coherent states, quantum discords and entanglements is also an interesting problem.

Testing quantum nonlocality with high probability using quantum mixed state based on hardy-type paradox

Liu Jin, Miao Bo, Jia Xin-Yan, Fan Dai-He
Acta Physica Sinica. 2019, 68 (23): 230302 doi: 10.7498/aps.68.20191125
Full Text: [PDF 898 KB] Download:(31)
Show Abstract
Quantum nonlocality is an important phenomenon predicted by quantum mechanics. It is also one of the most important characteristics that quantum theory is different from classical theory. Therefore, it is of great significance to test the quantum nonlocality with higher successful probability. In this paper, a testing logic based on Hardy-type paradox is proposed and its applicability is proved. Such a logic can be used to test the quantum nonlocality for both the quantum mixed state and the quantum pure state with a high successful probability. It is found that, for quantum pure states, the probability of successfully testing the quantum nonlocality first increases and then decreases with the increase of entanglement degree of quantum states. The maximum successful probability of the testing the quantum pure state is over 39%. Furthermore, taking the Werner-like state, a quantum mixed state for example, the high successful probability of testing the quantum nonlocality is investigated by using the proposed logic. It is found that with the increase of the purity of the quantum mixed state, the successful probability of testing the quantum nonlocal correlation will increase. Finally, the conditions and the range of testing quantum nonlocality with high successful probability for Werner states are given. It is found that for r = 0.599997, the Werner-like quantum mixed state has a maximum range (i.e. Tr(ρ2) ≥ 0.874696) of successfully testing the quantum nonlocality.

Influence of classical field driving on survival probability in quantum Zeno and anti-Zeno effect

Hu Yao-Hua, Wu Qin
Acta Physica Sinica. 2019, 68 (23): 230303 doi: 10.7498/aps.68.20191078
Full Text: [PDF 907 KB] Download:(25)
Show Abstract
The quantum system decay can be frozen and slowed down when it is repeatedly and frequently measured, which is described as the quantum Zeno effect (QZE). On the other hand, the evolution of the quantum system can be sped up if the measurement is not frequent enough, which is called quantum anti-Zeno effect (QAZE). Both the QZE and QAZE have been experimentally observed in many different physical setups, and have attracted tremendous theoretical and experimental interest due to their significant potential applications in quantum information processing.
A recent research has demonstrated that the effective lifetime of the quantum system when being measured repeatedly depends on the spectral density of the environment, the system parameters, and the system-environment coupling. Then, how to prolong the survival time of the quantum system subjected to being repeatedly measured is an issue that deserves to be studied. In the present paper, considered is a classical-field-driven two-level system interacting with a bosonic reservoir at zero temperature. We investigate the dynamics of the effective decay rate versus the measurement interval, and propose a scheme to prolong the lifetime of the quantum system subjected to being measured repeatedly, with a classical field driven. The results show that when the initial state of the quantum system is excited, QZE-to-QAZE transitions occurs several times. In an identical time interval, the decay rate for the initial superposition state is far smaller than that for the initial excited state. More importantly, the effective decay rate is very small when the classical driving is strong enough, which indicates that the classical driving can improve the survival probability of the two-level system subjected to being measured frequently and repeatedly. In addition, the environmental ohmicity plays an important role in keeping the quantum state alive. The detuning between the two-level system and the classical field has an adverse effect on the decay rate. In other words, the survival probability decreases as the detuning increases. Fortunately, this negative influence from the detuning can be suppressed by increasing the strength of classical driving or choosing the appropriate ohmicity parameter of the environment.

Landau damping and frequency-shift of (0, 0, 2) scissors mode in a disc-shaped Bose-Einstein condensate

Zhao Jun-Ya, Li Chen-Xu, Ma Xiao-Dong
Acta Physica Sinica. 2019, 68 (23): 230304 doi: 10.7498/aps.68.20190661
Full Text: [PDF 1337 KB] Download:(18)
Show Abstract
By using the Hartree-Fock-Bogoliubov approximation of mean-field theory and the analytic method based on Thomas-Feimi approximation, the Landau damping and frequency-shift of (0, 0, 2) scissors mode in a disc-shaped Bose-Einstein condensate are investigated and the damping rate and frequency-shift magnitude as well as their temperature dependence are calculated. In the calculation, the practical relaxations of the elementary excitations and the orthometric relation among the relaxations are considered in the relation for the perturbed eigenfrequency of mean-field theory to obtain the calculation formula of damping and frequency-shift, and the first-order approximation of Gaussian distribution function is employed for the ground-state wavefunction to eliminate the divergence of the three-mode coupling matrix elements in Thomas-Fermi approximation. Taking the same parameters of particle number, trapping frequency and anisotropy as those in relevent experiment research, our theoretical calculation results accord with the relevent experimental measurement results. Because of the complexity of the theory and the difficulty of calculation, most of mean-field theory researches on damping and frequency shift of collective excitation in one and two component Bose-Einstein condensates adopt semi-classical approximation, the quasi-particle excitation spectrum is regarded as continuously integrating each quasi-particle transition contribution to damping and frequency shift. In this paper, the damping and frequency shift are calculated according to the discrete quasi-particle excitation spectrum, and in the course of the study the improving of method of considering the practical relaxations of the elementary excitations and the orthometric relation among the relaxations is put forward. It is hoped that the method will have some reference value in the future work.

Electrical transport measurement system in pulsed high magnetic field based on rotation sample rod Hot!

Liu Qin-Ying, Wang Jun-Feng, Zuo Hua-Kun, Yang Ming, Han Xiao-Tao
Acta Physica Sinica. 2019, 68 (23): 230701 doi: 10.7498/aps.68.20191115
Full Text: [PDF 1387 KB] Download:(24)
Show Abstract
In recent years, measuring the electrical transport properties of materials in different directions of applied magnetic field has become an important experimental study of topological quantum materials. With the development of condensed matter physics, scientific research has shown that under the ultra-high intensity pulsed magnetic field, the electrical transport study of materials may extend to the quantum limit region, and more abundant physical phenomena will be observed. However, in the existing electric transport measurement system, the rotation sample rod under the action of steady-state field presents a large size and significant eddy current effect, which makes it difficult to meet the requirements for pulsed field measurement, and the current commercial physical property measurement system (PPMS) can only operate under ±16 T steady magnetic field. In addition, the conventional rotation sample rod encounters the problems of insufficient angular resolution and space utilization when used in pulsed high magnetic environment. So there is an urgent need to develop a higher performance rotation measurement system. In view of the above background, in this paper we present a kind of electrical transport measurement system designed by Wuhan National High Magnetic Field Center (WHMFC), which consists of five modules: pulse power supply, pulse magnet, control center, cryogenic system, and signal measurement. The key component is the sample measuring rod with rotation function, which restricts the movement of the drawbar through a double-groove structure to achieve an angular change in a range from -5° to 185°. An angle calibration coil is mounted on the back of the sample stage. Based on the double-calibration method, the angle control accuracy of 0.1° is achieved. The temperature, magnetoresistance and Hall resistance signal are collected by the integrated circuit on sample stage and extracted by compensation circuit and virtual digital lock-in amplifier, and the accuracy of electric transport measurement is better than 0.1 mΩ. Furthermore, the effect of eddycurrent and material deformation at low temperatures are completely eliminated by using polyetheretherketone material, which effectively improves the stability and reliability of the rotation sample rod. Using this measuring rod, we complete a series of experiments in the 8 mm sample cavity in the center of the pulse magnet: the minimum ambient temperature reaches 1.3 K, the maximum magnetic field strength arrives at 65 T, and the direction angle of the magnetic field is able to change in a 190° range. Thus the universally applicable measurement system of electric transport experiment in pulsed high magnetic field is successfully established. In this paper, we elaborate the principle and device components of the measurement system, the design and fabrication of the angle measuring rod, and the calibration principle and measurement process. Relevant experimental results show that the system has important application value in the research of 3D Fermi surface, topological insulator surface state, quantum limit transport, superconductivity analysis, etc. Based on this system, the electrical transport experimental system at WHMFC provides an effective means for the relevant research teams (home and abroad) engaged in the exploration of the intrinsic physical characteristics of quantum materials in extremely pulsed high magnetic field and low temperature environment.
NUCLEAR PHYSICS

Source boundary parameter of Monte Carlo inversion technology based on virtual source principle

Tian Zi-Ning, Ouyang Xiao-Ping, Chen Wei, Wang Xue-Mei, Deng Ning, Liu Wen-Biao, Tian Yan-Jie
Acta Physica Sinica. 2019, 68 (23): 232901 doi: 10.7498/aps.68.20191095
Full Text: [PDF 1067 KB] Download:(23)
Show Abstract
In the in situ γ spectrometer based measurement of “hot particular”, “radioactive collection point” and “radioactive collection area”, only the position of the pollution source can be located roughly, but its boundary parameters such as the thickness of pollution source cannot be given. In this paper, the application of virtual technology to the scanning of γ spectrometer is studied. We convert γ spectrometer measurement objects into a four-layer theoretical model, which are attenuation thickness + radioactive hot area + attenuation thickness + disturb source. Then, the source item layer is virtualized into a point source by using virtual technology. So, the theoretical model is further simplified. Then the detection efficiency and peak/valley ratio parameter of source term are simulated by Monte Carlo method. Finally, the source term parameters are retrieved by using the least square method, and thus establishing the theoretical method and procedure of inversion calculation of source boundary parameters. In this paper, the theoretical and experimental results are shown to be consistent with each other. So, this method is verified to be correct and practicable. Currently, the method can accurately determine the depth distribution parameters of radioactive contamination area for uniformly distributed radio nuclides. In conclusion, the technical achievements can be used to accurately determine the boundary range of the radioactive hot zone, thus realizing the purpose of reducing the waste disposal capacity during the treatment. At the same time, the determination of the inert layer thickness parameters of the target nuclear warhead of Nuclear Test Ban Treaty has a significant reference value.
ATOMIC AND MOLECULAR PHYSICS

Temperature measurement method of high temperature and high pressure flow field based on wavelength modulation spectroscopy technology Hot!

Zhang Bu-Qiang, Xu Zhen-Yu, Liu Jian-Guo, Yao Lu, Ruan Jun, Hu Jia-Yi, Xia Hui-Hui, Nie Wei, Yuan Feng, Kan Rui-Feng
Acta Physica Sinica. 2019, 68 (23): 233301 doi: 10.7498/aps.68.20190515
Full Text: [PDF 1404 KB] Download:(33)
Show Abstract
Temperature is one of the important parameters to measure the combustion efficiency. The measurement of temperature is of great significance for saving energy and reducing emission in industrial combustion process and diagnosing the engine state. The tunable diode laser absorption spectroscopy is a non-invasive measurement technology with strong environmental adaptability for fast, in-situ detection. Based on the three absorption lines of H2O at 7185.6 cm-1, 6807.8 cm-1 and 7444.35/37 cm-1, the wavelength modulated spectrum absorption model is established and laboratory-calibrated; using the background-subtracting WMS-2f/1f method and the best fit method, the temperature is measured. The outlet temperature of the single-head combustion chamber is accurately realized. The outlet temperature of the single-sector combustion chamber is also accurately measured. The measurement is verified in a pressure range of 3.39-10.58 atm and a temperature range of 958-1512 K. The time resolution of the measurement system is less than 1 ms, and the measurement error is less than 5.68%, thus verifying the practicality of the measurement method and the stability of the measurement system.

Measurement of collision frequency shift in strontium optical lattice clock

Lu Xiao-Tong, Li Ting, Kong De-Huan, Wang Ye-Bing, Chang Hong
Acta Physica Sinica. 2019, 68 (23): 233401 doi: 10.7498/aps.68.20191147
Full Text: [PDF 1007 KB] Download:(33)
Show Abstract
In a one-dimensional Fermion optical lattice clock, the p-wave scattering can occur when collision energy is sufficient to overcome the centrifugal barrier of p-wave scattering. According to Pauli exclusion principle, the s-wave scattering is forbidden between two identical Fermions. However, the s-wave scattering may also exist due to inhomogeneous excitation which leads to some difference between two Fermions. In terms of the uncertainty evaluation of a neutral atomic optical lattice clock, the frequency correction and uncertainty caused by atomic interaction cannot be ignored, and it will affect the evaluation of AC stark frequency shift. So the uncertainty evaluation of the collision frequency shift should be as small as possible. Only in this way can a neutral atomic optical lattice clock have a state-of-the-art performance. The collision frequency shift originates from the interaction between atoms trapped in an identical lattice. In this study, the collision frequency shift of 87Sr optical lattice clock at the National Timing Service Center is measured experimentally. A horizontal one-dimensional optical lattice is constructed. The number of tapped atoms is about 104 at a temperature of 3.4 μK. A laser is used to pump the atoms to either of the Zeeman energy levels of mF = ±9/2 in the ground state, and the clock transition spin polarization spectrum is obtained. In a spin polarized Fermions system, the collision frequency shift relating to atomic density is measured by the method of self-comparison. The method of self-comparison, which takes full advantage of the excellent short-term stability of the clock laser, can be used to measure the frequency difference caused by the variety of system parameters. Owing to the fact that the collision frequency shift is proportional to atomic density, the collision frequency shift can be measured by the method of self-comparison between high and low atomic density. In the experiment, the systematic state is changed between high and low atomic density by periodically changing the loading time of the first stage of cooling. In order to reduce the statistical uncertainty of the measurement, the collision frequency shift is separately measured 37 times. Finally, when the atomic density is 4×1010/cm3, the collision frequency shift is -0.13 Hz, and the statistical uncertainty of the measurement is 3.1×10-17. The Allan deviation of self-comparison between low and high atomic density reaches 4×10-17 after 8000 s averaging time, indicating that the accuracy of the measurement is reliable and on the order of 10-17. This work lays a foundation of the total uncertainty evaluation of 87Sr optical lattice clock.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

Generation of surface plasmon vortices based on double-layer Archimedes spirals

Wu Li-Xiang, Li Xin, Yang Yuan-Jie
Acta Physica Sinica. 2019, 68 (23): 234201 doi: 10.7498/aps.68.20190747
Full Text: [PDF 1108 KB] Download:(32)
Show Abstract
Surface plasmon polariton (SPP) is an electromagnetic oscillation which is produced by the interaction of free electrons on metal surface with incident light field. Using some specific metal metasurface structures, plasmonic vortices can be easily obtained. The SPP can well confine the light field within the interface between metal and medium. The SPP has two excellent characteristics: the ability to break through the diffraction limit and the strong field enhancing effect. Consequently, it has unique advantages in many applications, such as nanoparticle trapping, near-field imaging and sensing.
The key point lies in selecting the incident light and the construction of metasurface structure when we want to produce SPP vortices. Especially the construction of metasurface structure has great influence on the generation of SPP vortices. So far, many structures have been proposed to produce SPP vortices. In 2015, Byoungho Lee research group (Lee S Y, Kim S J, Kwon H, Lee B 2015 IEEE Photonics Technol. Lett. 27 705) designed a structure of double-ring distributed nanoslits which can produce high-order plasmonic vortices by circularly polarized light. In addition, the use of Archimedes slit structure to generate optical vortices is currently a more common method. More recently, a novel plasmonic vortex lens was proposed to produce SPP vortices with arbitrary topological charges. The plasmonic vortex lens consists of an array of gold film nanoslits, and the superposing of the SPP field excited by each nanoslit can produce a composite plasmonic vortex. Here, we propose a novel spiral metasurface structure for generating surface plasmonic vortices. Using the combination of theoretical analysis and finite difference time domain (FDTD) simulation, we find that the topological charge quantity of surface plasmon vortices can be changed by adjusting five parameters, namely, the chirality of incident circularly polarized light, the difference in radius between inner and outer nanocavity array, the rotational velocity factor of nanocavity array, the number of segments of spiral, and the pitch of spiral. This metasurface structure has many adjustable parameters and each parameter can influence the final surface plasmon vortices. Therefore, the plasmonic vortices with an arbitrary topological charge quantity can be generated and manipulated simply by using such a metasurface structure. This work can be expected to have a very broad prospect of applications in super resolution microscopy, quantum cryptography, nanoparticle manipulation, optical data storage, and optical communication.

Relevance of the heralded efficiency of the heralded single-photon source to the heralded basis

Yang Hong-En, Wei Lian-Fu
Acta Physica Sinica. 2019, 68 (23): 234202 doi: 10.7498/aps.68.20190532
Full Text: [PDF 1154 KB] Download:(23)
Show Abstract
The method by measuring one photon of an entangled two-photon pair to simultaneously herald another photon as the single photon, is one of the important ways to prepare the desired single-photon source. However, achieving high herald efficiency is still an open problem. In this paper, with the polarization entangled photon pairs generated by the parametric down-conversion process in the I-type phase-matched BBO (β-BaB2O4) nonlinear crystal, we investigate how the herald efficiency of the single-photon along the ideal path depends on the selection of the heralded basis of the photon in the signal path. An extended Hanbury-Brown-Twiss experimental system is built with a fiber polarizing beam splitter and three single-photon detectors, to experimentally measure the herald efficiency of the heralded single-photon source. Our results show that with the present polarization entangled-photon system whose quality is relatively low, the herald efficiency with the |+/-> heralded basis is enhanced 4% compared with that with the |H/V> heralded basis.

Analysis of entanglement source based on coherent feedback control

Zhou Yao-Yao, Li Peng-Fei, Yan Zhi-Hui, Jia Xiao-Jun
Acta Physica Sinica. 2019, 68 (23): 234203 doi: 10.7498/aps.68.20191168
Full Text: [PDF 1128 KB] Download:(20)
Show Abstract
Entangled state of light with quantum correlations between amplitude and phase quadratures is a necessary quantum resource in optical continuous variable (CV) quantum information systems. The CV Einstein-Podolsky-Rosen (EPR) entangled optical field is one of the most basic quantum resources, which can be generated by a non-degenerate optical parametric amplifier (NOPA) operated below the threshold pump power. Manipulating the EPR entangled state of light effectively can break through the limitation of the imperfect performance of optical components in optical cavities and then further improve the entanglement level under certain conditions. So it is necessary to find out an effective optical scheme of manipulating quantum state of light. The non-measurement based coherent feedback control (CFC) system without introducing any extra noise into the controlled system, can be used to stabilize, control and improve the performance of various quantum systems. Only by selecting the right experimental parameters can the CFC system play its positive role in reaching a maximum efficacy. The key optical component, i.e. optical controller in CFC system, greatly affects the final manipulation effects. In 2015, using the method of CFC, our research team experimentally realized the enhancement of entanglement to different levels by changing the optical controller with different transmissivity values for seed optical beams. At the same time, the threshold pump power of the NOPA is reduced to different levels also. Due to the technical reasons, the transmissivity of the optical controller selected in the experiment is almost the same for the signal optical field and idle optical field. In this paper, we emphasize the condition that the transmissivity of the optical controller for the signal optical field is different from that for idle optical field. Firstly, we theoretically study the final effects of manipulating entanglement source by using the coherent feedback optical cavity under the above conditions. It is concluded that if the transmittance of control beam splitter (CBS) is low, the feedback control optical cavity works best when the optical controller has different transmissivity for signal optical beam and idle optical beam, and that if the transmittance of CBS is high, the transmittance of the optical controller for signal optical beam almost equals that for idle optical beam to make the feedback control optical cavity work best. Then we theoretically investigate the dependence of the quantum correlation noise of the quadrature amplitude and quadrature phase of the output optical fields from CFC-NOPA system on other physical parameters. Combining with the actual experimental conditions, we can find the optimal transmissivity of the optical controller and appropriate range of frequency to optimize the effects of CFC, which provides the basis for correctly selecting the actual experimental parameters in CFC systems. Theoretical analysis results also show that with the higher input and output coupling efficiency and higher nonlinear conversion efficiency of NOPA, the entangled state of light with higher entanglement degree can be obtained experimentally. This provides the reference for obtaining better quantum resources needed for studying the CV quantum information.

Master oscillator pulse nonlinear amplifier system based on all polarization-maintaining fiber

Zhang Tong, Zhang Wei-Guang, Cai Ya-Jun, Hu Xiao-Hong, Feng Ye, Wang Yi-Shan, Yu Jia
Acta Physica Sinica. 2019, 68 (23): 234204 doi: 10.7498/aps.68.20190925
Full Text: [PDF 1360 KB] Download:(36)
Show Abstract
The erbium-doped fiber oscillators, especially mode-locked fiber oscillators for generating femtosecond pulses, cannot meet the requirements for most of modern industrial applications because they are resticted by the low power and the limited wavelength range. In order to solve this problem, lots of efforts have been made both theoretically and experimentally, to improve the chirped pulse amplification (CPA) technology. The emergence of CPA technology greatly enhances the energy of laser pulses. The broadening and compressing of the laser pulses are both always dependent on the improving of spatial optical components, such as grating pairs. However, the use of this kind of method can increase the complexity of the amplification system to a certain extent. This may be an essential reason why more and more researchers pay attention to all fiber amplification system. In this paper, the master oscillator pulse nonlinear amplifier system based on all polarization- maintaining fiber is proposed, which is mainly composed of an oscillator based on the semiconductor saturable absorption mirror and linear cavity, a two-stage amplification and a pulse compressor constructed by a single-mode conductive fiber with anomalous dispersion. Using this system, we obtain ultrashort laser pulses in the 1.5 nm band whose pulse width equals 44 fs and single pulse energy reaches about 1 nJ. The system is not only compact and miniaturized but also stable and reliable due to the all polarization-maintaining fiber. Subsequently, an MgO doped periodically poled lithium niobite crystal with a thickness of 1 mm is used to implement frequency doubling. The pulses from the system are accurately focused on a position where the crystal polarization period is 19.8 μm with help of some wave plates and lenses. Adjusting the optical path reasonably and optimizing colliminated focusing parameters, the double-frequency pulse output with certral wavelength of 779 nm and average power of 60 W is obtained, in which the conversion efficiency reaches 30%. The result shows that the master oscillator pulse nonlinear amplifier system based on all polarization maintaining fiber can produce satisfactory ultrashort pulses. It is a new idea for generating the ultrashort femtosecond pulses in the near-infrared band.

Method of correcting tilt aberration for array laser of incoherent combination

Deng Wan-Tao, Zhao Gang, Xia Hui-Jun, Zhang Mao, Yang Yi-Fan
Acta Physica Sinica. 2019, 68 (23): 234205 doi: 10.7498/aps.68.20190961
Full Text: [PDF 1210 KB] Download:(15)
Show Abstract
The beam quality of array lasers which propagate in atmosphere will degrade in far-field. Therefore, the ultimate efficiency of combined lasers will be affected if no compensation measure is taken in some typical systems such as high energy system. Based on the model of array lasers with incoherent combination, laser propagation in atmosphere is simulated by generating a random atmospheric turbulence phase screen to modulate the phase of the laser beam. The distorted wavefront of atmospheric turbulence is divided according to the array distribution. The phase generated by tilt aberration coefficient which is solved by the method of fitting sub-wavefront data is eliminated in the phase of sub-beam, which simulates the process of correcting tilt aberration. The simulation results show that comparing with the case of tilt aberration, the power in the bucket (PIB) and the Strehl rate (SR) of combined lasers focusing in far-field are improved when the tilt aberration influenced by the same atmospheric turbulence phase screen is corrected. At the same time, coherence length ranging from 4 cm to 45 cm is used to characterize atmospheric turbulence of different intensities. At each coherent length, the PIB and SR are calculated when the distances of propagation of lasers are 2 km and 3 km, separately. The simulation results show that although PIB and SR before and after tilt aberration are corrected, they become worse with the decrease of coherence length, and PIB and SR are improved more obviously when tilt aberration is corrected in stronger turbulence. An experiment in the case of 2 km is carried out by using a prototype of incoherent combination, and the data are obtained by measuring the focused spot at the target. The measurement results confirm that the correcting of tilt aberration can improve the beam quality of array lasers with incoherent combination in far-field. In summary, the research conducted in this work can obtain tilt aberration accurately and the corresponding method of correction is easy to implement, which can provide supporting data for improving the performances high energy laser systems.

Defect states and vibration energy recovery of novel two-dimensional piezoelectric phononic crystal plate

Sun Wei-Bin, Wang Ting, Sun Xiao-Wei, Kang Tai-Feng, Tan Zi-Hao, Liu Zi-Jiang
Acta Physica Sinica. 2019, 68 (23): 234206 doi: 10.7498/aps.68.20190260
Full Text: [PDF 2144 KB] Download:(18)
Show Abstract
The band structure and transmission characteristics of a new two-dimensional (2D) piezoelectric phononic crystal plate consisting of four epoxy short plates periodically connected with a square lattice of a prismatic piezoelectric material coated with plexiglass are investigated by supercell method and finite element method. By changing the electric boundary conditions imposed on the upper and lower surfaces of piezoelectric scatterers, a point defect waveguide with adjustable paths is formed, which overcomes the limitation of immutability in the direction of the vibration waveguide, with material and structural parameters fixed. Then the controlling of the piezoelectric effect can change the material parameters of piezoelectric components in phononic crystals, showing that the piezoelectric constants have a great influence on the complete bandgap, which is beneficial to the formation of defect states; when the frequency of the defect state appears in the band gap, the frequency-responding range of the defect state expands. The analysis of the displacement vector field indicates that the strain energy in the resonance of the new structure is almost completely limited to the upper and lower surfaces of the central piezoelectric scatterer. We use the recycling circuit to connect the electrodes on the upper and lower surfaces of the piezoelectric sheet. At this time, the output electrical energy can supply the power to the DC load, and the mechanical energy of vibration can be converted into electrical energy. The results of this work provide a reference for the self-powered technology of waveguide and wireless sensor device with adjustable path.

Bandgap and transmission spectrum characteristics of multilayered acoustic metamaterials with magnetorheological elastomer

Liu Shao-Gang, Zhao Yue-Chao, Zhao Dan
Acta Physica Sinica. 2019, 68 (23): 234301 doi: 10.7498/aps.68.20191334
Full Text: [PDF 1325 KB] Download:(45)
Show Abstract
One of the challenges relating to acoustic metamaterials is to achieve a tunable performance without modifying the structure. In this paper, we propose two types of acoustic metamaterials with a magnetorheological elastomer (MRE), and their tunable band gap structures and the transmission spectra are investigated by the finite element method (FEM). The MRE acts as a cladding layer, and its shear modulus can be changed by an externally applied magnetic field. The cell resonance frequency of acoustic metamaterial is changed. The band gap structures and the transmission spectra of the two kinds of acoustic metamaterials are calculated under various magnetic fields, and it is found that the frequency and width of band gap, the maximum attenuation frequency and transmission loss of transmission spectrum increase with externally applied magnetic field intensity increasing. Meanwhile, two types of the mass-spring models are used to estimate the band gap frequencies of the two kinds of acoustic metamaterials. The FEM results are in good agreement with the estimation results. In addition, the effects of material parameters of core and shell and filling rate on the band gap and transmission spectrum are also studied. The effects of core material parameters on the band gap and transmission spectrum of single-layer acoustic metamaterial are analyzed. It is found that the core mass has an effect on the band gap frequency and width, and the elastic parameter of the core affects the transmission loss of the transmission spectrum. The influences of core and shell material parameter on the band gap and transmission spectrum of double-layer acoustic metamaterial is analyzed by the control variable method. The results show that the core and shell mass affect the band gap frequency, width and pass-band width, and the elastic parameter of the core and the shell affect the transmission loss of the transmission spectrum. As the filling rate increases, the band gap frequency and width of the single- and double-layer MRE acoustic metamaterial increase, the maximum attenuation frequency of the transmission spectrum does not change, and the transmission loss increases. These results will greatly contribute to the application of acoustic metamaterials to controlling the active noise and vibration.

Influence of large bubbles on cavitation effect of small bubbles in cavitation multi-bubbles

Qinghim, Naranmandula
Acta Physica Sinica. 2019, 68 (23): 234302 doi: 10.7498/aps.68.20191198
Full Text: [PDF 1633 KB] Download:(38)
Show Abstract
In previous papers, researchers generally adopted a simplified assumption that there is a single type of bubble in liquid. In this paper, two simplified bubbles models are established based on the shape and structure of cavitation bubbles formed in ultrasonic field, i.e. linear model consisting of three bubbles and cluster model composed of five bubbles, and each model is assumed to consist of two types of bubbles. The influences of large bubbles on cavitation effect of small bubble in the middle for three- and five-bubble model are numerically studied by using the modified Keller-Miksis equation and van der Waals equation. The changes of the expansion radius of the small bubble in the middle, the temperature in the small bubble and the secondary Bjerknes force between large bubble and small bubble with the increase of the initial radius of large bubbles are mainly investigated. In the calculation, it is assumed that the locations of bubbles stay unchanged and the shape of bubbles remains spherical in the oscillation process. Meanwhile, the time-delay effect on the secondary Bjerknes force can be neglected because the sound wave speed is very fast in water and the bubbles in the liquid can oscillate synchronously. The calculation results show that the expansion of small bubble in the middle can be completely suppressed or delayed when the initial radius and the number of bubbles are appropriate on condition that the distance between large and small bubble, the driving sound pressure and frequency of the applied sound field stay unchanged. The main reason for delayed expansion is that the total pressure acting on small bubbles is delayed to form a negative pressure in the process of the change. The collapse time of delayed expansion of small bubble is basically the same as that of large bubbles, which makes small bubble collapsed rapidly and thoroughly under the strong radiative barotropic effect of large bubble's collapse, and leads the maximum temperature in the small bubble to be higher than that of the single bubble with the same initial radius and the small bubble with normal expansion. In addition, when the expansion of small bubble is delayed, the secondary Bjerknes force between the large bubble and the small bubble appears to be repulsive first and attractive then. This rule is different from the change rule of the secondary Bjerknes force between the two bubbles in normal expansion. The results in this paper have significant theoretical guidance for specific problems such as suppressing liquid cavitation or enhancing liquid cavitation effect by the manual injection of large bubbles.

Similarity and vortex-acoustic lock-on behavior in thermoacoustic oscillation involving vortex shedding

Wang Wei, Deguchi Yoshihiro, He Yong-Sen, Zhang Jia-Zhong
Acta Physica Sinica. 2019, 68 (23): 234303 doi: 10.7498/aps.68.20190663
Full Text: [PDF 5551 KB] Download:(23)
Show Abstract
In engineering, the combustion chamber with a backward step is very popular, and it is a kind of flame stabilizer. In this type of combustion chamber, there will be shedding vortices at the step due to the instability of the flow field. The shedding vortices will carry reactants to move downstream and burn, resulting in unstable heat release and then pressure and velocity fluctuations of the sound field, thereby, finally, forming a combustion-vortex-acoustic interaction process. If a positive feedback loop is formed between the unstable heat release and the pressure fluctuation of sound field, combustion instability will occur, and it is also referred to as thermoacoustic oscillation due to vortex shedding. Combustion instability frequently occurs in many practical systems or equipment, and its induced significant pressure oscillations have a serious influence on the normal operation of the equipment. Recently, the combustion instability has been extensively studied experimentally, but the theoretical investigation on its nature is still rare. Since combustion instability is a complicated nonlinear phenomenon, it is necessary to study its nature from the viewpoint of nonlinear dynamics. Based on the one-dimensional simplified model of thermoacoustic instability involving vortex shedding proposed by Matveev and Culick, the typical nonlinear phenomenon in thermoacoustic oscillation induced by vortex shedding is studied. The study focuses on the initial value sensitivity of the system, the influence of key parameters on thermoacoustic oscillation, and the phenomenon of vortex-acoustic lock-on. Firstly, the Galerkin method is used to approximate the governing equation, and the partial differential equations are reduced to a set of ordinary differential equations. Then, the first ten modes are selected, and the pressure and velocity fluctuations of sound field under different system parameters are obtained by MATLAB program. Finally, the thermoacoustic instability of the system under different initial disturbances, the influences of different steady flow velocity on the thermoacoustic oscillation of the system, and the phenomenon of vortex-acoustic lock-on in thermoacoustic oscillation are studied in detail. The results show that the system of thermoacoustic oscillation involving vortex shedding is extremely sensitive to initial values, and there are a rich variety of nonlinear phenomena. With steady flow velocity increasing, the amplitude of pressure fluctuation augments generally. However, the similar structures are found in several intervals of steady flow velocity, and the amplitude first decreases and then increases. In particular, it is verified that the system oscillates periodically by integer (fp/fs) multiple of the vortex impinging frequency (fs), that is, the vortex-acoustic frequency locking with the number of revolutions fp/fs, which is found in experiment and can be regarded as an important characteristic of periodic thermoacoustic oscillation.

Mixing characteristics of ellipsoidal granular materials in horizontal rotating drum based on analysis by discrete element method

Wang Si-Qiang, Ji Shun-Ying
Acta Physica Sinica. 2019, 68 (23): 234501 doi: 10.7498/aps.68.20191071
Full Text: [PDF 1597 KB] Download:(19)
Show Abstract
Granular flow in the drum widely appears in the fields of industrial production, and discrete element method (DEM) proves to be a critical tool for studying the flow characteristics of granular materials. Considering simple contact and efficient calculations, the three-dimensional spheres are originally adopted by the DEM. Therefore, the DEM simulations mainly focus on spherical particles, while the dynamics of non-spherical particles in rotating drums is relatively rarely studied. It is reported that particle shape significantly affects the macroscopic and microscopic properties of the granular flow. Compared with spherical particles, non-spherical particles have low fluidity and great interlock. Meanwhile, it is questionable whether conclusions drawn from spherical particle systems can be transplanted to non-spherical particle systems. In this work, super-quadric equations based on continuous function representation are used to describe the spherical and ellipsoidal particles. Considering the complex contact detection between particles, the Newton iteration algorithm is used to solve the non-linear equations. Meanwhile, a non-linear contact model considering the equivalent radius of curvature at the local contact point is used to calculate the contact force between the super-quadric elements.
To examine the validity of DEM model, we compare our simulated results with the previous experimental results for mixing process of ellipsoids, and this method is verified by good agreement between the simulated results and the experimental results. According to the aforementioned method, the influences of rotating speed, fill level, and aspect ratio on the mixing rate are discussed. The results show that the granular system reaches the cascading regime and the S-shaped surface of the granular bed is observed. In addition, Lacey mixing index is used to quantify the mixing of granular systems, and the mixing rate is obtained by fitting the Lacey mixing index. The mixing rate increases as the rotating speed increases. At the same rotating speed, the mixing rate of ellipsoids is faster than that of spheres. Meanwhile, the ellipsoidal particles have the fastest mixing rate when the aspect ratio is 0.75 or 1.50. When the aspect ratio is less than 0.75, the mixing ratio increases as the aspect ratio increases; when the aspect ratio is greater than 1.50, the mixing ratio decreases as the aspect ratio increases. Moreover, more pronounced velocity stratification is observed for ellipsoids. The translational kinetic energy of ellipsoidal particles is higher than that of spherical particles, and their rotational kinetic energy is lower than that of spheres. The aspect ratio of particles can adjust the contact mode between particles and cause the interlock. It means that the relative rotation between particles is limited and the efficiency of the external energy transferring to the non-spherical system may be improved.

Three-dimensional 12-velocity multiple-relaxation-time lattice Boltzmann model of incompressible flows

Hu Jia-Yi, Zhang Wen-Huan, Chai Zhen-Hua, Shi Bao-Chang, Wang Yi-Hang
Acta Physica Sinica. 2019, 68 (23): 234701 doi: 10.7498/aps.68.20190984
Full Text: [PDF 1516 KB] Download:(28)
Show Abstract
In order to improve the computational efficiency of multiple-relaxation-time lattice Boltzmann model (MRT), a 12-velocity multiple-relaxation-time lattice Boltzmann model (iD3Q12 MRT model) for three-dimensional incompressible flows is proposed in this work by using an inversion method. This model has higher computational efficiency than the commonly used D3Q13 MRT model in principle. In numerical simulations, the accuracy and stability of iD3Q12 MRT model are validated by simulating different flows, including steady Poiseuille flow driven by pressure, unsteady pulsatile flow driven by periodic pressure and lid-driven cavity flow. We also compare the iD3Q12 MRT model with the 13-velocity multiple-relaxation-time lattice Boltzmann model(He-Luo D3Q13 MRT model).
For the Poiseuille flow and pulsatile flow, the numerical solutions of the iD3Q12 MRT model agree well with the analytical solutions. In terms of accuracy, the iD3Q12 MRT model and He-Luo D3Q13 MRT model are used to simulate Poiseuille flow with different parameters. The global relative errors of the two models are identical. Similarly, we also simulate the pulsatile flow to calculate the global relative errors of flow fields at different times and different lattice spacing. It is found that the global relative errors of the iD3Q12 MRT model are smaller than those of the He-Luo D3Q13 MRT model, and both models have the second-order spatial accuracy. Furthermore, we also simulate the pulsatile flow by changing the lattice spacing or relaxation time when the maximal pressure drop of the channel is increased, and it is found that the global relative errors calculated by the iD3Q12 MRT model are smaller than those by the He-Luo D3Q13 MRT model in most cases, but the iD3Q12 MRT model diverges when the maximal pressure drop of the channel is large. This indicates that the iD3Q12 MRT model is more accurate than the He-Luo D3Q13 MRT model in simulating unsteady pulsatile flow, but less stable. For the lid-driven cavity flow, the results show that the numerical results of the iD3Q12 MRT model agree well with those given by Ku et al [Ku H C, Hirsh R S, Taylor T D 1987 J. Comput. Phys. 70 439]. In terms of stability, the iD3Q12 MRT model is quantitatively less stable than He-Luo D3Q13 MRT model.

Temperature charateristics of droplet impacting on static hot pool

Fang Long, Chen Guo-Ding
Acta Physica Sinica. 2019, 68 (23): 234702 doi: 10.7498/aps.68.20190809
Full Text: [PDF 1217 KB] Download:(20)
Show Abstract
A high speed camera-infrared camera synchronous shoot device is built to record the process of cold droplet impacting on hot pool and lots of experiments have been done in this paper. The mixing morphology and the temperature variation of the impact area are observed and analyzed based on simultaneous images taken by the infrared camera and the high speed camera. The influences of the impact conditions on mixing and heat transfer during droplet impacting on hot pool are also studied and then the dimensionless relationship between mean temperature of the impact area and impact condition is established. The experimental results show that the mixing of cold liquid from droplet and hot pool is one of the main reasons for the temperature increase in impact area. The cold droplet does not integrate with hot pool immediately at the beginning of impact and the droplet is deformed into a shape of “crescent moon” which is trapped near the crater. The interface between cold liquid from droplet and hot pool can be observed in a simultaneous image. When the crater begins to collapse, the mixing liquid is mainly divided into two parts: one part is left and curled at the bottom of the pool while the other part is rising with the central jet. Despite the stagnation at the beginning, the mean temperature increases with time going by in the early stage. However the growth trend is interrupted by the cavity collapse. The mean temperature arrives at a peak after the crater has reached its maximum depth. The peak of the dimensionless temperature Tpeak* increases with the Weber number increasing and Tpeak* can be described as Tpeak* = 0.34We0.15. The dimensionless time of the peak Tpeak increases with the Froude number increasing. In this paper, we also find that the dimensionless time of the peak Tpeak can be described as Tpeak = 0.85Fr5/8. After the mean temperature reaches the peak, the growth trend presents a trend of fluctuations. The shape of the trend line during this stage is related to Weber number. When the Weber number is small, the growth trend of mean temperature decreases in a short period of time and then restores and increases with time going by. When the Weber number is bigger, the growth rate becomes smoother during the long fluctuation period. The mean temperature will increase very slowly at the end of the impact. Only some cold spot are left on the surface during this period and the rising of the mean temperature becomes steady and slow.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

Laser energy coupling and partitioning of silver spheral hohlraum with one laser entrance hole

Yu Bo, Yin Chuan-Sheng, Sun Chuan-Kui, Hou Li-Fei, Song Tian-Ming, Du Hua-Bing, Guan Zan-Yang, Zhang Wen-Hai, Yuan Zheng, Li Chao-Guang, Dong Yun-Song, Jiang Wei, Huang Tian-Xuan, Pu Yu-Dong, Yan Ji, Chen Zhong-Jing, Yang Jia-Min, Jiang Shao-En
Acta Physica Sinica. 2019, 68 (23): 235201 doi: 10.7498/aps.68.20191026
Full Text: [PDF 1151 KB] Download:(9)
Show Abstract
The matter can be instantaneously heated up to a high energy density state by the high power laser. When the high power laser is injected into silver spherical hohlraum, the high temperature radiation source formed in the hohlraum can drive the high velocity blast wave in the laboratory to study various astrophysical phenomena such as supernova remnants, stellar jets, etc. As the basis of laser driven blast wave experiments, the first experimental results of energy coupling and partitioning of silver spherical hohlraum with one laser entrance hole (LEH) on Shenguang Ⅲ prototype laser facility are introduced in this work. Four beams with 3.2 kJ of laser energy in a 1ns square laser pulse from the upper hemisphere are used to heat the silver spherical hohlraum targets. The silver spherical hohlraum targets are 800 μm-diameter and 650 μm-diameter LEH, and are fabricated by electroforming silver onto an acrylic mandrel. The laser coupling and partitioning to the targets are investigated by using the optical and X-ray diagnostics. The experimental results show that the radiation temperature is beyond 240 eV, the laser-to-X-ray conversion efficiency of silver hohlraum is 0.68 and the silver albedo is 0.83. With the driving of the high temperature radiation source, most of laser energy is coupled to the residual shell, and the high velocity blast wave can be generated. The laser energy not coupled to the target is lost through scattering light, emitting hot electrons and radiating X-rays. The experimental results show that the fraction of energy lost due to the scattering light is 15%, that due to emitting the total hot electrons is less than 1%, almost 30% of the laser energy is lost from the LEH by radiating the X-ray flux, almost 9% of the laser energy leaks from the spherical shell consisting of the 5.6 μm-thick Ag layer and 10 μm-thick CH layer through the X-ray radiation flux, and 45% of the laser energy is converted into the kinetic energy and internal energy of the remaining spherical shell. Therefore, more than 50% of the laser energy will be used to drive the high velocity blast wave in the subsequent experiments. After 950 ps, the silver plasma is concentrated in the center of the silver spherical hohlraum, which does not affect the injection of 1ns laser. The experiment on energy coupling and partitioning of a spherical silver hohlraum laser is carried out for the first time on Shenguang Ⅲ prototype laser facility, which lays a foundation for the subsequent experiments on laser driven blast wave.

Experimental study of magnetic circuit and antenna position influence on performance of 2 cm electron cyclotron resonance ion thruster

Xia Xu, Yang Juan, Jin Yi-Zhou, Hang Guan-Rong, Fu Yu-Liang, Hu Zhan
Acta Physica Sinica. 2019, 68 (23): 235202 doi: 10.7498/aps.68.20191122
Full Text: [PDF 1069 KB] Download:(15)
Show Abstract
The advantages of miniature electron cyclotron resonance ion thruster (ECRIT) for space propulsion are long-life and simple-structure. The magnetic circuit and antenna position of ECRIT are crucial in the electron heating, plasma confinement and transportation process, which affect the beam extraction and the coupling voltage of neutralizer. In this article, the experimental studies on the ion beam extraction and coupling voltage of 2 cm ECRIT with different magnetic circuits and antenna positions are carried out. By comparing the beam extraction characteristics of the ion source and neutralizer of different magnetic circuits, a reasonable magnetic circuit structure is selected. And the influences of different antenna positions on the beam are compared. The influences of the magnetic circuit and antenna position on the performance of ECRIT are summarized to obtain a reasonable thruster structure. The experimental results show that the extracted beam increases with microwave power and xenon mass flow rate increasing. When the spatial position of antenna is fixed, a suitable magnetic circuit structure can increase electron heating and reduce particle loss, which is suitable for extracting ions and reducing the coupling voltage. With a suitable magnetic circuit, there is a suitable antenna position favourable for extracting ions and reducing the coupling voltage. According to the experimental results, the optimal structure of ion source and neutralizer are selected for neutralization experiments. The results show that when the neutralizer works, the beam extraction of the ion source is affected very little. When the neutralizer and ion source operate under the parameters of power and mass flow rate, respectively, of 1 W and 0.1 sccm (1 sccm = 1 mL/min), and also 2 W and 0.3 sccm, the thruster can operate coordinately to generate an ion beam of 5.3 mA, a discharge loss of 337.5 W/A, propellant utilization efficiency of 24.7%, thrust force of 368.6 μN, thrust specific impulse of 1277.6 s, and neutralizer coupling voltage of 17.4 V. The results can conduce to understanding the mechanism of the thruster and thus providing a reference for its design and performance optimization.
Acta Physica Sinica
Accepts
Note: The papers published below will continue to be available from this page until they are assigned to an issue. To see an article, click its [PDF] link. To review many abstracts, check the boxes to the left of the titles you want, and click the 'Selected articles' button. To see one abstract at a time, click its [Abstract] link.
»

The Effect of Collision Parameter on a Magnetized Electronegative Plasma Sheath Structure

Accept: 2016-10-11
Full Text: PDF (0KB) (117)
Show Abstract
The structure of an electronegative plasma sheath in an oblique magnetic field is investigated. More over, the collisions between positive ions and neutral particles are taken into account. It is assumed that the system consists of hot electrons, hot negative ions and cold positive ions. Also the negative ions and the electrons are assumed to be described by the Boltzmann distributions of their own temperatures, and the accelerated positive ions are treated by means of the continuity and momentum balance equations through the sheath region. In addition, the assumption that the collision cross section has a power law dependence on the positive velocity is introduced. After theoretical derivation, an exact of sheath criterion is obtained. The numerical simulation results include the distributions of the positive ions density for different invariable ion Mach number satisfying Bohm criterion, the comparison of net space charge distributions for variable and invariable ion Mach number. Furthermore, three species of charged particles density, the net space charge and the spatial electric potential in the sheath are studied numerically for different collision parameters under the condition of the fixed ion Mach number. The results show that the ion Mach number has not only the lower limit but also the upper limit. The ion Mach number affects the sheath structure by influencing the distribution of the positive ion density, and different conclusions can be obtained because ion Mach number is adopted as variable or invariable value while discussing the effects of the other variables which can result in the variety of the ion Mach number on the sheath formation. The reason is the actual sheath structure modification brought on by the variation of a parameter can be resolved into two parts. One is the sheath formation change caused directly by the variation of the parameter, the other is the sheath formation change caused by the Bohm criterion modification which the variation of the parameter results in. Therefore, an identical ion Mach number should be adopted when researching the direct effects of a parameter variety on plasma sheath structure. In addition, it is concluded that the collisions between positive ions and neutral particles make positive ions density curve higher and electrons’ lower than the case without collisions. Negative ions density does not alter significantly whether there exists collision or not. Besides there is a peak in the profile of the net space charge while in the presence of ion-neutral collision and the net space charge peak moves toward the sheath edge. The spatial potential increases and the sheath thickness decreases on account of the presence of the collisions between ions and neutral particles.
»

Calculation of Hamilton energy function of dynamical systems by using Helmholtz theorem

null
Accept: 2016-10-11
Full Text: PDF (0KB) (103)
Show Abstract
The Helmholtz theorem confirmed that any vector field could be decomposed of gradient and rotational field. The supply and transmission of energy occur during the propagation of electromagnetic wave accompanied by variation of electromagnetic field, thus the dynamical oscillators and neurons can absorb and release energy in presence of complex electromagnetic condition. Indeed, the energy in nonlinear circuit is often time-varying when the capacitor is in charged or discharged, and occurrence of electromagnetic induction is available. Those nonlinear oscillating circuits can be mapped into dynamical systems by using scale transformation. Based on mean field theory, the energy exchange and transmission between electronic field and magnetic field could be estimated by appropriate nonlinear dynamical equations for oscillating circuits. In this paper, it investigates the calculation of Hamilton energy for a class of dimensionless dynamical systems based on Helmholtz’s theorem. Furthermore, scale transformation could be used to develop dynamical equations from the realistic nonlinear oscillating circuit, so the Hamilton energy function could be approached effectively. These results could be much useful for self-adaptive control of dynamical systems.
»

Ballistic thermal rectification in the three-terminal graphene nanojunction with asymmetric connection angles

null
Accept: 2016-10-11
Full Text: PDF (0KB) (72)
Show Abstract
By using the nonequilibrium Green’s function method, the ballistic thermal rectification in the three-terminal graphene nanojunction is studied. The dynamics of atoms are described by the interatomic fourth-nearest neighbor force-constant model. The nanojunction has a Y-shaped structure, created by a combination of a straight graphene nanoribbon and a leaning branch as the control terminal holding a fixed temperature. No heat flux flows through the control terminal. There exists a temperature bias between the two ends of the graphene nanoribbon served as the left and right terminals, respectively. The primary goal of this paper is to demonstrate that the ballistic thermal rectification can be introduced by the asymmetric structure with different connection angles between terminals. The control terminal has a smaller connection angle with respect to the left terminal than to the right terminal. The forward direction is defined as being from the left terminal to the right terminal. The results demonstrate that, given the same control temperature and absolute temperature bias, the heat flux in the graphene nanoribbon tends to run preferentially along the forward direction. When the difference between the connection angles increases, the rectification ratio rises. Compared to the zigzag graphene nanoribbon, the rectification ratio of the armchair nanoribbon is more sensitive to the direction the control terminal. However, the greatest rectification ratio is found in the zigzag graphene nanoribbon which has a connection angle of 30 degrees with respect to the armchair branch. In addition, the direction of the control terminal can be adjusted to raise more than 50% of the rectification ratio of the graphene thermal recti?er based on the width discrepancy between the left and right terminals. The mechanism of the ballistic thermal recti?cation is also discussed. In the three-terminal graphene nanojunction, a smaller connection angle with respect to the control terminal leads to more phonon scattering. The confirmation of this conclusion comes from a comparison of phonon transmission between different couples of terminals, which shows that, in most of the frequency spectrum, the phonon transmission between the control terminal and the left terminal is smaller than that between the control terminal and the right terminal. Given the same control terminal temperature and temperature bias, the asymmetric connection angles therefore will introduce a higher average temperature of the left and right terminals, and a larger heat flux in the forward process. Moreover, the average temperature difference between in the forward process and in the reverse process is found to be proportional to the temperature bias, and the proportionality coefficient will get bigger if the asymmetry is strengthened.
»

The Propagation Properties of Vortex Beams in a Ring Photonic Crystal Fiber

null
Accept: 2016-10-11
Full Text: PDF (0KB) (26)
Show Abstract
In the last decade, the vortex beams have received lots of attention for their orbital angular momentum. When they are applied to optical fiber communication field, the data channels will increase and information propagation speed will be effectively improved. Recently, researchers have shown the capability of long length stably propagation, nonlinear frequency conversion and mode division multiplexing of vortex modes in a ring fiber. Due to the photonic crystal fiber (PCF) has very flexible design degrees of freedom, it will enable a wide range of propagation properties. In this paper, A SiO2 air-holes ring PCF is proposed for separation and propagation of optical vortex modes. By using COMSOL Multiphysics software, the vortex modes(TE01, HE_21^± and TM01) are simulated and calculated. The differences of the effective refractive index between them are 4.59×〖10〗^(-4) and 3.62×〖10〗^(-4) respectively. One can analyze the propagation properties of vortex beams in the ring PCF by changing the size of first layer air holes’ radius and air hole pitch. When the incident light wavelength of TE01 mode ranges from 1650 nm to 1950 nm, this ring PCF can achieve a total dispersion variation between 44.18 to 45.83 ps?nm^(-1)?km^(-1), which is tend to be flat. When incident light wavelength is 1550 nm, the nonlinear coefficient of TE01 mode vortex light is 1.37 W^(-1)?km^(-1); Due to the long wavelength light is easier to leakage through the cladding than the short wavelength light, the confinement loss increases with the wavelength. When incident light wavelength is 2000 nm, there is still an eight-orders-of-magnitude of the low confinement loss. Theoretically, flat dispersion and low loss vortex beams in this fiber can be beneficial to propagate stably, and the vortex modes lay the foundation for long distance propagation in the optical fiber. In the future, this ring PCF will be used in optical fiber communication field and application in aspects such as continuous spectrum research, which can make it have immense advantage to traditional fibers.
»

Penta-decomposition of instantaneous field in spanwise-rotating turbulent plane Couette flow

null
Accept: 2016-10-11
Full Text: PDF (0KB) (181)
Show Abstract
Spanwise-rotating turbulent plane Couette flow (RPCF) is one of the fundamental prototypes for wall-bounded turbulent flows in the rotating reference frames. In this turbulent problem, there are large-scale roll cells, which are widely studied. In this paper, a penta-decomposition method is proposed to separate the instantaneous velocity and the total kinetic energy into five parts, including a mean part, a streamwise part and a cross-flow part of the secondary flow, and a streamwise part and a cross-flow part of the residual field, aimed to explore the energy balance and transfer among different shares of the turbulent kinetic energy in RPCF at Reynolds number Rew=Uwh/ν=1300 (here, Uw is the half the wall velocity difference, and h is half channel-height) and rotation number Ro=2Ωzh/Uw (Ωz is the constant angular velocity in the spanwise direction) in the range of 0≤Ro≤0.9. The results show that the energy is transferred between streamwise part (cross-flow part) of secondary flows and residual field through the correlation between the vorticity of secondary flows and shear stress of residual field. The rotation term acts as a bridge to transfer the energy between streamwise part and cross-flow part of secondary flows (residual field). Moreover, pressure-strain redistribution term also plays an important role in the energy transfer between streamwise part and cross-flow part in residual field. For the streamwise part of residual field, in certain rotate rates, the energy obtained from the streamwise part of secondary flows is larger than that got from mean flow, implying that the streamwise motions of secondary flows have a significant impact on the streamwise motions of residual field.
»

A fast particle simulation method for calculating the multipactor threshold based on the frequency domain solutions in microwave devices

null
Accept: 2016-10-11
Full Text: PDF (0KB) (105)
Show Abstract
In order to compute the multipactor thresholds of microwave devices with high ef?ciency and precision, a novel fast particle-in-cell (PIC) method is proposed, which takes advantages of the frequency-domain (FD) electromagnetic field solver of CST Microwave Studio (MWS). At the initial stage of multipactor (when there are not many electrons in the devices), the self-consistent field generated by the electrons is much smaller than the applied electromagnetic field. Therefore it can be ignored in calculating the multipactor threshold and this will significantly reduce the computation burden. During simulations of multipactor processes, the FD fields pre-calculated by CST MWS are converted into time-domain (TD) scaling with the square root of the input power. Then the electrons are advanced by Boris algorithm. When the electrons hit the boundaries of the simulation region, where triangular facets from CST are used for discretization, the secondary electrons would be emitted. After series of simulations with variable input powers, the multipactor threshold is determined according to time evolutions of the electron number. As verifications, the multipactor thresholds in a parallel plate and a coaxial transmission line are investigated. Compared with the results of CST Particle Studio (PS), the fast method obtains almost the same thresholds, while the computational efficiency is improved more than 1 order of magnitude. Since the self-consistent field generated by the electrons is ignored in the fast method and it is considered in CST PS, the results validate that the self-consistent field can be ignored in calculating the multipactor threshold. Finally, taking a parallel plate transmission line and a stepped impedance transformer as examples, we studied the effects of the number of initial macro-particles on the calculation precision. When the initial particles are so few that it can hardly reflect the randomness of the multipactor process, it results in a higher calculated value. With the increase of the number of initial macro-particles, the calculated multipactor threshold is lower and more accurate. It is convergent when the number reaches about 2000 for the parallel plate transmission line and 4000 for the stepped impedance transformer, respectively. Taking into account other microwave devices with more complex electromagnetic field distribution, in order to ensure precision, it is recommended to select the number of initial macro-particles 8000. In addition, although CST MWS was used to obtain the electromagnetic fields and boundary information in this paper, of course, other electromagnetic software (such as HFSS) can also be adopted as an alternation.
»

The effect of linear bubble vibration on wave propagation in unsaturated porous media containing air bubbles

null
Accept: 2016-10-11
Full Text: PDF (0KB) (283)
Show Abstract
Biot model is widely applied in geophysics, petroleum engineering, civil engineering and ocean engineering since it has been presented. This leads to a considerable development of the research on the wave propagation in saturated porous medium. However, fully saturated porous medium is rarely found in nature, almost all the rocks or soils contain two kinds of fluid, such as gas and petroleum. So many researches has been done on the wave propagation in unsaturated porous medium by domestic and abroad scholars. It is well known that the presence of a small volume of gas bubbles in a liquid can greatly alter the velocity and attenuation of acoustic waves in the liquid. Evidence is beginning to accumulate that the velocity and attenuation of acoustic waves in a saturated marine sediment can be affected by the presence of gas bubbles in the saturating liquid. To investigate the sound propagation in porous media when the pore water contains a small amount of air bubbles, this paper integrates the volume vibration of bubbles in pore water into the continuity equation of pore-fluid filtration in porous media based on Biot theory, so as to obtain the continuity equation of pore-fluid filtration with bubble volume vibration. On this basis, according to the relationship between the instantaneous radius of bubbles and the background pressure of the medium under the linear vibration of bubbles, as well as the equations of motion of the fluid medium and porous medium, a new displacement vector wave equation of porous media under the influence of bubbles is derived, which establishes the model for the sound velocity dispersion and attenuation prediction under the unsaturated porous media. The presence of air bubbles increases the compressibility of pore fluid, which leads to the decrease in the sound velocity of the bubbly saturated porous media. When the wave frequency equals to the resonance frequency of the bubbles, the bubbles in pore water will produce resonance; the medium will present to be highly dispersive and the velocity can greatly exceed the gas-free velocity, but these have not been measured in field data; and the absorption cross section of the air bubble can reach the maximum, which leads to the maximum attenuation of the porous media. It should be noted that the attenuation coefficient calculated with this model is related to the damping of bubble motion(radiation, thermal and internal friction) and the dissipation of the relative motion between the pore water and porous solid frame. The obtained numerical analysis is consistent with the above conclusions, which indicates that the volume concentration, the bubble size and the excitation frequency of sound field are important parameters affecting the sound wave propagation in the saturated porous media containing few bubbles.
»

Ferroelectric phase transition of perovskite SnTiO3 based on first principles

null
Accept: 2016-10-11
Full Text: PDF (0KB) (86)
Show Abstract
Due to their spontaneous polarization, ferroelectric materials have excellent dielectric, piezoelectric, pyroelectric and other properties, which enable them to be used in many applications, such as capacitors, filters, sensors, detectors, and transducers, among others. In this paper, we employ a first-principles-based effective Hamiltonian method to investigate perovskite SnTiO$_3$, obtaining essential coefficients for the effective Hamiltonian via ab initio computations, which are used in subsequent Monte-Carlo simulations to predict the phase transition temperature of SnTiO$_3$, and different structural phases involved in such phase transition.
»

Nonlocal Symmetries and Interaction Solutions of the (2+1)-dimensional Higher Order Broer-Kaup System

xiangpeng xin Hanze Liu Xi-qiang LIU
Accept: 2016-10-11
Full Text: PDF (0KB) (286)
Show Abstract
The (2+1)-dimensional higher-order Broer-Kaup (HBK) system is studied by nonlocal symmetry method and consistent tanh expansion (CTE) method. In this paper, via the localization of the residual symmetries, the nonlocal symmetries are localized to Lie point symmetries and symmetry groups are also obtained. Many types of soliton solutions and interaction solutions among different nonlinear excitations such as solitons, periodic waves etc. are constructed. In order to study their dynamic behaviors, corresponding images are explicitly given.
»

Development of a intranuclear-cascade code CBIM applicable to the nuclear reaction with incident particle energy above 45MeV

null
Accept: 2016-10-11
Full Text: PDF (0KB) (78)
Show Abstract
The Monte Carlo intra-nuclear cascade program CBIM has been developed for describing nuclear reactions involving protons, neutrons and pions on complex nuclei. In order to describe cascade process, several simplifications have been made in the following: firstly, neither reaction, reflection, refraction, nor ionization will be taken into account before the incident particle enters the target nucleus; secondly, target nucleus is regarded as spherical and the atom number should be greater than 2; thirdly, the knocked nucleon is determined by cross section sampling; last, in the center-of-mass frame, the scattering angle is sampled based on differential cross section distribution.. The basis physics model bases on the above assumptions and Bertini intra-nuclear cascade model; meanwhile, nucleon-nucleon angle differential distributions of INCL in the center-of-mass frame have been introduced to overcome the shortage of Bertini model. The interactions between nucleon and nucleon or between nucleon and pion, for example, elastic scattering, pion production and charge exchange, are simulated in the code. In the particles collision, the nucleon density changes with the target nucleus radius; and the interaction cross sections refer to 22 kinds of experimental cross sections in Bertini model. The intra-nuclear cascades induced by 45MeV~3500MeV neutron, proton or pion below 2500MeV can be simulated by this code. Finally, comparisons with experiment on reaction cross section over the energy range 60~378MeV, and some simulation results by MCNPX, GEANT4 and PHITS over the energy range 65~3000MeV, the CBIM results are in reasonable agreement with them over the broad energy range considered.
»

Omnidirectional photonic bandgap of the one-dimensional plasma photonic crystal based on a novel Fibonacci quasiperiodic structure

Accept: 2016-10-11
Full Text: PDF (0KB) (304)
Show Abstract
Take the binary one-dimensional plasma photonic crystal based on Fibonacci quasiperiodic structure as an object, on the basis of the photonic bandgap characteristics of the structure with different initial sequence and number of period, a novel structure of one-dimensional plasma photonic crystal is proposed in this paper to enlarge the omnidirectional photonic bandgap (OPBG). Compared with previously reported structures in literatures, this structure is simpler in configuration with fewer layers and materials, and its OPBG width is wider. The influence of the parameters of the plasma material, such as the thickness, plasma frequency and collision frequency, on the OPBG characteristics of this structure is systematically discussed and compared with that of the structure in literatures. The research results can provide important theoretical guidance for the design of novel omnidirectional reflectors.
»

Quantum secure direct communication protocol based on the mixture of Bell state particles and single photons

Zheng-Wen CAO
Accept: 2016-10-11
Full Text: PDF (0KB) (34)
Show Abstract
By studying the properties of the mixture of Bell state particles and single photons, the paper designs a quantum code scheme with high coding capacity, and proposes a novel quantum secure direct communication protocol with high transmission efficiency. Alice prepares Bell state particles and single photons, and divides Bell state particles into two sequences $S_A$ and $S_B$. $S_B$ is sent to Bob for the first security check using quantum correlation properties of particles. When the check result shows that the quantum channel is safe, using designed quantum code scheme, Alice encodes her classical message on the mixed quantum state sequence of Bell sequence $S_A$ and single photon sequence $S_S$. Then, some single photons that are used for security check are re-inserted randomly into the encoded sequence, and the order of particles is rearranged to ensure to check Eve's attack. Alice sends the new sequence to Bob. Bob delays and receives it. And then, the quantum channel is conducted security check for the second time. The transmission error rate is calculated, if the error rate is lower than the tolerance threshold, the channel is safe. Bob decodes and reads Alice's message. The first security check is to determine whether quantum channel is safe. The second security check could test whether there are eavesdroppers during information transmission. Safety analysis is done by using quantum information theory to the proposed protocol. The error rate introduced by Eve and the amount of information by Eve are calculated. It is showed that this protocol can effectively resist measurement-resend attack, intercept-resend attack, auxiliary particle attack, denial of service attack and Trojan attack. Among them, auxiliary particle attack is analyzed in details. The transmission efficiency and coding capacity are also analyzed. The transmission efficiency is 2, the quantum bit rate is 1, and the coding capacity is that a quantum state can encode three bits of classical messages. We also compare the proposed protocol to many existing popular protocols in terms of efficiency, e.g., Ping-Pong protocol, Deng,F.G. et al.'s Two-step and One-pad-time quantum secure direct communication protocol, Wang,J. et al.'s quantum secure direct communication protocol based on entanglement swapping and Quan,D.X. et al.'s one-way quantum secure direct communication protocol based on single photon. It is proved that this proposed protocol has higher transmission efficiency. In addition, complex U operation and entanglement swapping are not used, and implementation process is simplified. However, this protocol is devoted to theoretical research of quantum secure direct communication. There are still some difficulties in the practical application. For example, the storage technology of quantum states is not mature at present. It is not easy to prepare and measure Bell state particles and combine them with single photons, and so on. The implementation of this protocol depends on the development of quantum technology in the future.
»

The Relationship between Dielectric Properties and Nanoparticle Dispersion of Nano- SiO2/Epoxy Composites

null
Accept: 2016-10-11
Full Text: PDF (0KB) (50)
Show Abstract
Nano-SiO2 was modified by silane coupling agent and modified nano-SiO2 powder and nano-SiO2 dispersing liquid was obtained. Unmodified and modified nano-SiO2/Epoxy composites made by “mechanical mixing method”, and modified namo-Silica/Epoxy composites made by “bubble mixing method” were prepared, respectively. The content of nano-SiO2 in the composite is 2wt%, 3wt%, 4wt%, 5wt% and 6wt%. Breakdown strength and corona-resistance characteristics of the composites were tested. The results show that, with the increase of nano-SiO2 loading, the breakdown strength and corona-resistance of nano-SiO2/Epoxy composites increase. The maximum breakdown strength of namo-Silica/Epoxy composites was appeared when the nano-Silica content is 5wt%. The SEM images of 5wt% nano-Silica loading composites were analyzed by Software Image J, and the Morisita’s Index method was used to evaluate the dispersion of nano-Silica particles in the matrix quantitatively. The best dispersion was found in the composites made by “bubble mixing method”. The relationship between dielectric properties and nano-particle dispersions of nano-Silica/Epoxy composites was discussed.
»

Combined noise source identification method based on spherical microphone array with random unifrom distribution of elements

null
Accept: 2016-10-11
Full Text: PDF (0KB) (79)
Show Abstract
As the developing of techlology, noise controlling is paied wide attention in recent years. Noise source identification is the key step for noise controlling. Spherical microphone array, which can located the noise source of arbitrary direction in three dimensional space, is widely used for noise source identification in recent years. Conventional methods for noise source localization include spherical near field acoustic holography and spherical focused beamforming. The acoustic quantities are reconstructed by using spherical near field acoustic holography method to realize the noise source identification, while the noise source can also be located by using focused beamforming based on spherical harmonic wave decomposition. However, both these methods have their own limitations while being used in noise source identification. Spherical near field acoustic holography has low resolution in high frequency with far distance from noise source to measurement array for noise source identification, whereas the spherical focused beamforming has low localization resolution in low frequency. Noise source identification is discussed here and a 64-element microphone spherical array with randomly uniform distribution of elements is designed. The combination methods of noise source identification by using spherical near field acoustic holography and mode decomposition focused beamforming are researched. The performance of the proposed combination methods is simulated, and an experiment of noise source identification is carried out based on the designed spherical microphone array to test the validity of proposed method. The dividing frequency point is when selecting noise source identification methods between near field acoustic holography of spherical wave decomposition by using the spherical array designed in this paper. Research results show that high resolution of noise source identification can be obtained by using near field acoustic holography when reconstruction frequency is with a distance from noise source to the center of spherical array, while high resolution of noise source localization can be achieved by using spherical wave decomposition beamforming when signal’s frequency is with a distance from noise source to the center of spherical array. Spherical array with random uniform distribution of elements maintains stable identification ability in all bearing. Spherical near field acoustic holography has high resolution distinguish ability in near field and low frequency, while focused beamforming method has high resolution distinguish ability in far field and high frequency. Therefore the noise source can be efficiently identified by using the proposed combined method of near field holography and focused beamforming with less elements and small aperture spherical microphone array.
»

Optimization design of a Gamma-to-Electron spectrometer for high energy gammas induced by fusion

null
Accept: 2016-10-11
Full Text: PDF (0KB) (280)
Show Abstract
Apart from neutrons, the fusion core produces gamma rays during one fusion reaction. The spectrum of gamma ray can provide very important information for fusion diagnosis. However, due to the gamma energy and yield in one fusion pulse, the gamma spectrometer used should have high detection efficiency and energy resolution. The concept of a Gamma-to-Electron magnetic spectrometer GEMS provides the idea to build up such a spectrometer to meet this requirement. Based on this concept design, four important parts of this facility are investigated. The first part is the gamma-electron converter. The main physics processes include Compton scattering of gamma ray with converter material generating electron, the electron Multiple Coulomb scattering (MCS) inside the converter and the electron attenuation. Affected by the thickness of convector, these processes gives a complex influence on the detection efficiency and angular-energy distribution of the electrons which are emitted from the downstream face of the convector. The Monte Carlo code Geant4 is employed to investigated the functions of Compton scattering, MCS and converter thick on the angular-energy distribution. The second one is the collimation. The collimation is used to select the forward direction election, the performance of cutoff angle of the collimator on the detection efficiency and resolutions, as well as the correlation between electron transportation direction and energy, are also studied using Geant4 code. The third part is the dipole magnetic field. There are several parameters of geometric and magnetic, therefore, a multi-thread parallelized Genetic algorithm is developed to get the best result. Both the irregular geometry (shape) and dipole magnetic field strength are optimized to achieve the best energy resolution and detection efficiency. The obtained magnetic field has intensity less than 100 Gauss, and its performance on gathering elections is also verified by Geant4 code. The last one is the location of electron detectors. The study shows that all the electron detectors should be located according to not a straight line but a quadratic curve. Then the optimized spectrometer is simulated by Geant4 to get the responses of gamma rays with various energies. For the gammas provided by fusion reaction, the simulation shows that when the neutron yield is about 2.5×1015 and 1.2×1016, the energy resolution reaches 0.5 MeV and 0.25 MeV, respectively, provided that different thick Be converters are employed. All in all, this optimized GEMS can be employed to measure the spectrum of gamma rays generated by the fusion reaction.
»

Influnence of Nonspherical Effects on the Secondary Bjerknes Force in a Strong Acoustic Field

null
Accept: 2016-10-11
Full Text: PDF (0KB) (86)
Show Abstract
The secondary Bjerknes force between bubbles in an acoustic field is a well-known acoustic phenomenon. The major theoretically researches of the secondary Bjerknes force were owing to two spherical bubbles. The secondary Bjerknes force between two spherical bubbles which is calculated based on the linear equations is very small and negligible, therefore these theoretically researches did not give a well explanation for the phenomenon, such as “streamer formation” and Multi-bubble sonoluminescence (MBSL). Experiments of sonoluminescence (SL) show that bubbles in a sound field are not entirely spherical bubbles. Nonspherical effects have an important influence on the secondary Bjerknes force when two bubbles come close to each other in a strong acoustic field (>1.0×〖10〗^5 Pa). How does the shape distortion of a nonspherical bubble cause the change of the secondary Bjerknes force between two bubbles, and the secondary Bjerknes force how to affect the oscillation and movement of bubbles are major problems which we wish to solve. The of the secondary Bjerknes force between a nonspherical bubble and a spherical bubble is obtained by considering the shape oscillation of a nonspherical bubble. We numerical simulate the secondary Bjerknes force between a nonspherical bubble and a spherical bubble based on the nonlinear oscillation equations of two bubbles, and compare the secondary Bjerknes force between a nonspherical bubble and a spherical bubble to the secondary Bjerknes force between two spherical bubbles in the same condition. We discuss the influence of nonspherical effects on the secondary Bjerknes force between two bubbles. The results show that when the amplitude of driving pressure is greater than the Blake threshold of a nonspherical bubble and makes the bubble oscillate stably, the secondary Bjerknes force between this nonspherical bubble and a spherical bubble is different to the secondary Bjerknes force between two spherical bubbles in direction and magnitude. The secondary Bjerknes force between a nonspherical bubble and a spherical bubble is much bigger than that of two spherical bubbles. The interactional distance of the secondary Bjerknes force between a nonspherical bubble and a spherical bubble is further than that of two spherical bubbles. The secondary Bjerknes force between a spherical bubble and a nonspherical bubble depends on the radii of two bubbles, distance between two bubbles, shape mode of the nonspherical bubble and the amplitude of driving pressure. Our research is more close to the actual bubbles in liquid. We also prove that big mutual interaction between bubbles is mainly cause for the formation of a stable structure between bubbles. For bubbles, big mutual interaction causes the cavitation become easier. These results are important to explain the phenomenon in an acoustic field, such as “streamer formation” and Multi-bubble sonoluminescence (MBSL).
»

The Principle and Application of Diagonal Reducing Method in the Complex Noise Fields

null
Accept: 2016-10-11
Full Text: PDF (0KB) (289)
Show Abstract
Acoustic environment has low signal-to-noise ratio (SNR); hence, array signal processing is always used for noise reduction and signal enhancement. Because the delay-and-sum beamforming method performs robust, so it is almost widely used, but the array gain is limited by the array aperture. The actual underwater ambient noise is complex, which includes uncorrelated noise and correlated noise. The noise power of each array element is unequal. The noise covariance matrix is not a scaled identity matrix. Consequently, the performance of array signal processing method decreases obviously. Aiming at these two problems, the diagonal reducing method of the covariance matrix in the complex noise fields is proposed. Firstly, a reducing matrix, which is defined as a diagonal matrix with unequal diagonal elements, is subtracted from the covariance matrix so as to reduce the noise, and a new matrix is obtained. Secondly, the delay-and-sum beamforming is done by using the new matrix to obtain the beaming output. The analytic solution and approximate solution of reducing matrix are obtained under the constraint condition that the output SNR attains its maximum. Thirdly, the estimation of the reducing matrix is determined by minimizing the function that is defined as the error between the covariance matrix and the estimated covariance matrix. This minimization problem is accomplished in an iterative method. Fourthly, if the noise is uniform white noise or the nonuniform white noise, this proposed method performs well. While, under the complex noise field the performance of the proposed method may be deteriorated. So the effects of the correlation of the noise field and the input SNR on the estimated error is analyzed. In fact, the weaker the correlation is, or the smaller the input SNR is, the smaller the estimated error is. Lastly, the simulation experiment and the lake trial are implemented. The simulation results show that the diagonal reducing method of the covariance matrix reduces some ambient noise, the noise output power is decreased, the output SNR is increased, and the proposed method improves performance of array signal processing. The experimental results show that the output SNR of the target using the proposed method is increased by about 14 dB. The diagonal reducing method of covariance matrix has definite value to engineering application, and is computationally attractive.
»

Moving target compressive imaging based on improved row scanning measurement matrices

null
Accept: 2016-10-11
Full Text: PDF (0KB) (70)
Show Abstract
Abstract: Moving target imaging (MTI) plays an important role in practical applications. How to capture dynamic images of the targets with high quality is a front-burner issue in the field of MTI. In order to improve the reconstruction quality, a new MTI model based on compressed sensing (CS) is proposed here, applying a sampling protocol of the row-scanning together with a motion measurement matrix constructed by our own. It is proved by the simulation and the experimental results that a relatively higher quality can be achieved through this approach. Furthermore, an evaluation criterion of reconstructed images is introduced to analyze the relationship between the imaging quality and the moving speed of the target. By contrast, the performance of our algorithm is much better than that of traditional CS algorithms under the same moving speed condition. As a result, it suggests that our imaging method may have a great application prospect in the earth observation of unmanned aerial vehicles, video monitoring in the product line and other fields.
»

Spatial Correlation of Underwater Bubble clouds Based on Acoustic Scattering

null
Accept: 2016-10-11
Full Text: PDF (0KB) (286)
Show Abstract
Using effective medium theory to describe acoustic scattering from bubble clouds, one of the underlying assumptions shows that the probability of an individual bubble being located at some position in space is independent of the locations of other bubbles. However, bubbles within naturally occurring clouds are usually influenced by the motion of the fluids which makes they become preferentially concentrated or clustered. According to Weber’s method, it is a useful way to importing spatial correlation function to describe this phenomenon in bubble clouds. The spatial correlation function is contained in acoustic scattering and it is important to notice that the spatial correlation should be dependent of the position and radius of each bubble due to the ‘‘hole correction’’ or the effect of the dynamics of the fluids. Because of these reasons, it is hard to invert the spatial distribution of bubble clouds using spatial correlation function in acoustic scattering. A method is described here in which bubble clouds are separated into many small subareas and the conception called effective spatial correlation function which is the statistic of spatial correlation function used to describe the correlation between each subarea of bubble clouds. Since the effective spatial correlation function is independent of bubbles’ radius and positions, the bubble clouds’ distribution and the trend of clustering can be inverted by using this function. The result of simulation indicates that the effective spatial correlation function can precisely track the position of the clustering center, even the clustering center covered by other bubble clouds can be detected. Using multi-bean sonar measuring the bubbly ship wake generated by a small trial vessel, the method is used to invert the spatial distribution and clustering centers of bubble field in the ship wake. The results show that effective spatial correlation function accurately inverts the distribution and clustering centers of bubbles in ship wake. Furthermore, the method presented in this paper could distinguish the bubble clouds caused by different reasons and detect upper ocean bubble clouds covered by other bubbles generated by wave breaking.
»

Uncertainty Quantification in the Calculation of keff Using Sensitity and Stochastic Sampling method

null
Accept: 2016-10-11
Full Text: PDF (0KB) (44)
Show Abstract
In the neutronics simulation of nuclear reactor, the uncertainties associated to the integral parameters due to the uncertainties in nuclear data are usually quantified using the sensitivity and uncertainty (S/U) analysis method based on the perturbation theory. S/U analysis method is only applicable to the linear model, moreover neutronics code generally can not be directly used in sensitivity analysis. Sampling approach, which evaluating the uncertainties by performing a set of stochastic simulations, is easy to implement and the uncertainties quantified is close to exact. The function of uncertainty quantification based on sampling approach have been added to uncertainty analysis code SURE. Before applying the sampling method to the uncertainty quantification in the simulation of complex problems, it is necessary to carry out a careful verification. The uncertainties of the calculated effective neutron multiplication factor keff for two selected simple critical benchmark experimental model are quantified using SU method and sampling method respectively. The keff uncertainties due to all nuclides and reaction types nuclear data quantified by two methods are in good agreement, and the correctness of the sampling function of SURE code is verified. The keffs distributions from sampling method obey normal distribution, which embodies a linear relation between input nuclear data and output keff in the range of the uncertainty range of nuclear data, and sensitivity analysis method is adaptable to quantify uncertainty of calculated keff.
»

A super-resolution infrared microscopy based on a doughnut pump beam

null
Accept: 2016-10-11
Full Text: PDF (0KB) (287)
Show Abstract
This paper presents an approach to break through the diffraction limitation in infrared microscopies. In this method, instead of Gaussian pump beam, an intensive vortex beam is firstly focused on the sample, leading to saturation absorption of the peripheral molecules in the point spread function (PSF). The vortex beam is followed by a Gaussian beam with the same wavelength, which can only be absorbed by the molecules near the center, resulting in shrunken PSF which means higher resolution. Furthermore, the PSF of a system based on this approach is numerically simulated. With an 100 nJ pulse energy vortex beam and a 0.1 nJ pulse energy probe beam, the theoretical resolution (full width at half maximum, FWHM) is measured to be about 236 nm which is 14 times better than that of the traditional infrared microscopy.
»

Fast Bayesian Blind Restoration for Single Defocus Image with Iterative Joint Bilateral Filters

null
Accept: 2016-10-11
Full Text: PDF (0KB) (63)
Show Abstract
It is significant to realize effective defocus image restoration for acquiring clear image in military and geological examination field. Most of existing algorithms have the problems of large computational cost, ringing and noise sensitivity, hence a novel approach by iterative joint bilateral filtering under Bayesian framework is proposed. Firstly, it utilizes defocus image depth estimation to compute the point spread function in the Bayesian framework. Then a minimum optimization problem is built to represent the blind restoration problem. After inferring the solution procedure of the minimum optimization problem, we find that the joint bilateral filters can be used to search the optimal solution, which not only simplify the searching procedure but also reduce the computational cost. Finally, an iterative joint bilateral filtering was designed to realize the image restoration. That means the original restored image obtained from the bilateral filtering is used to design the guide image for the joint bilateral filters, and the guide image will serve as the input of the optimization problem for acquiring the better optimal result. This procedure was repeated until convergence. The experiment results indicate that this method can yield the ringing, reduce the computational cost and remove the noise. Generally speaking, the average pixel error of 85% images is under 0.03, which has improved 19% comparing with the same error rang of existing algorithms. And 78% shorter than those of compared algorithms. It can be used in the engineering practice of blind restoration for single defocus image.
»

First-principles study on the thermodynamic stabilities and electronic structures of long-period stacking ordered phases in the Mg-Y-Cu alloys

null
Accept: 2016-10-11
Full Text: PDF (0KB) (282)
Show Abstract
A first-principles method based on density functional theory has been used to investigate thermodynamic stability and electronic characteristics of long-period stacking ordered (LPSO) phases 14H and 18R (18R(m),18R(t)) in Mg–Y–Cu alloys. The present calculations are performed using Vienna Ab-initio Simulation Package (VASP) with projector augmented plane wave pseudopotential, and generalized gradient approximation is used to treat with and describe the exchange-correlation interaction. The plane wave cutoff energy is set to 360 eV, the forces on all the atoms is less than 0.02 eV/?. The calculated negative enthalpies of formation show that both 14H and 18R can exist in Mg–Y–Cu system, 14H and 18R are stable with respect to the Mg, Cu and Y elements, the reaction energies indicate that 14H is more stable than 18R. The density of states (DOS) of these phases reveals that the main bonding peaks of 14H is located at energy range between -6.82 eV and 2.09 eV, those of 18R(m) at energy range between -6.82 eV and 2.02 eV, and 18R(t) at energy range between -6.82 eV and 1.98 eV. The Cu 3d orbits, Y 4d orbits, Mg 3s and Mg 2p orbits are broadly distributed in the entire region, while Cu 4s orbits, Y 4s and Y 4p orbits are very weak in whole region. For 14H,18R(m) and 18R(t) phases, the bonding originates mainly from the valence electrons of Mg 3s, Mg2p, Cu 3d and Y 4d orbits. The presence of pseudogap indicates that the bonds in 14H and 18R phases are noticeable covalent. In addition, the charge density on (0 0 0 1) plane of 14H and 18R phases are analyzed, and the results indicate that the Cu-Y bonds exhibits covalent feature in 14H and 18R, the covalent bonding of 14H phase is stronger than that of 18R phase.
»

A broadband low-frequency sound insulation structure based on two-dimensionally inbuilt Helmholtz resonators

null
Accept: 2016-10-11
Full Text: PDF (0KB) (65)
Show Abstract
A man-made acoustic structure with broadband low-frequency sound insulation property is designed based on circularly inbuilt Helmholtz resonators. Beyond this structure, a two-dimensional quiet zone can be created. Being the same as the simulating model, an experimental structure is fabricated. Experiments are carried out to study its sound insulation properties. The experimental results are very coincident with the simulating one, which show that this structure has an excellent sound insulation effect in the frequency band of 680-1050Hz, and the maximum insulation sound pressure level can reach 41dB. Meanwhile, the distribution of the two-dimensional sound field above this structure is measured. The results point out that the range of the insulation area can be changed with the change of the incident frequency. In addition, the sound insulation effect is sensitive to the resonant state of the Helmholtz resonators. This work will be of help for designing new sound protection devices.
»

Total Dose Dependence of Hot Carrier Injection Effect in the NMOS Devices

null
Accept: 2016-10-11
Full Text: PDF (0KB) (235)
Show Abstract
The equipments and devices which were long-time running in space were affected by space radiation effects and hot carrier injection effects at the same time which would reduce their optional times. Normally, the single mechanism test simulation method was used on the ground simulation test but the multi-mechanism effects was affected the space equipments and devices, included total irradiation dose effect, hot carrier injection effect, and so on. The total dose dependence of hot carrier injection (HCI) effect in the 0.35μm NMOS Devices was studied in this paper. Three samples were test with different conditions (sample 1# with TID and HCI test, sample 2# with TID, annealing and HCI test, sample 3# only with HCI test). The results shows that threshold voltage of NMOS devices with 5000s HCI test after 100krad (Si) total dose radiation shift negatively then positively during total dose irradiation test and HCI test,and it was more than the devices without radiation test. But the threshold voltage shift of NMOS devices with 5000s HCI test and 200hours annealing test after TID test was more than the devices without radiation test and lower than the devices without annealing test. That was, the parameters of NMOS device varied faster with the association effects (included total dose irradiation effect and HCI effect) than with single mechanism effect. It was indicated that the hot electrons were trapped by the oxide trap charges induced by irradiation effect and then became recombination centre. And then the oxide trap charges induced by irradiation effect reduced and became to negative electronic. The interface trap charges induced by irradiation effect were reduced and then increased and it was because that the electrons of hole-electron pairs in the Si-SiO2 interface were recombined by oxide traps in the oxide during the forepart of HCI test but then the electrons were trapped by interface traps in the Si-SiO2 interface because the electrons from source area were injected to interface during the HCI test. So the threshold voltage shift was positively due to the negative oxide trap charges and interface trap charges. The association effect was attributed to the reduction of oxide traps induced by recombination with hot electrons and the increase of the interface traps induced by irradiating trapped with hot electrons.
»

Optoelectronic properties of N/B doped graphene

null
Accept: 2016-10-11
Full Text: PDF (0KB) (288)
Show Abstract
Since its discovery in 2004, graphene has attracted great attention because of its unique chemical bonding structure, which has excellent chemical, thermal, mechanical, electrical and optical properties. Due to the zero band gap material, graphene has limited its development in the field of Nano Electronics. Only expanding the band gap of the graphene can promote the application of graphene in Nano Electronics. In this paper, we constructed three models of intrinsic graphene, N-doped graphene and B-doped graphene. The energy band structures, electronic density of states and optical properties of N/B doped graphene with intrinsic graphene and different doping concentrations were studied. The absorption spectra, the reflection spectra, the refractive index, the conductivity and the dielectric function were studied. The study shows that the electronic states near the Fermi level of N/B doped graphene are mainly composed of C-2p and N-2p/B-2p orbitals, and N/B doping can induce the change of the Fermi level and the photoelectric properties of graphene. The conclusion of this paper can provide a theoretical basis for the application of graphene in optoelectronic devices.
»

The study of the dynamic of the slow electrons transmitted through straight glass capillary and tapered glass capillary

null
Accept: 2016-08-18
Full Text: PDF (0KB) (15)
Show Abstract
It was found that the transmission rate of the electrons through insulating capillaries as a function of the time/incident charge is not the same as that for the ions. The question arouse that, by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the followed electrons, substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolution of the transmission of electrons through a straight glass tube and a tapered glass capillary. This would reveal the details that how and/or if the negative charge patches can be formed when the electron are being transported through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform was developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams through a small hole with the diameter of 0.5 mm was obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitted through the glass tube/capillary was observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then back again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fast discharge of the deposited charge, leading to an increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge, leads to a decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate transmission of electrons, similar to the guiding of positive charged ions. This suggests that if the stable transmission needs to be reached for the production of the electron micro-beam by using tapered glass capillaries, the steps has to be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference for electrons in transmission through the insulating capillary from that of highly charged ions.
»

aaaa

null
Accept: 2016-08-18
Full Text: PDF (0KB) (25)
Show Abstract
bbbbb
»

internuclear-distance-dependent ionization of H$_2^+$ in strong laser fields in a classical perspective

null
Accept: 2016-08-18
Full Text: PDF (0KB) (23)
Show Abstract
The enhanced ionization of H$_2^+$ in strong laser fields is studied by numerically simulating the classical Hamiltonian equation with the fix-nuclei approximation. The classical trajectory of the electron shows the electron gains energy from the laser field by circulating one electron, then passes through the interatomic barrier and move around the other nucleus before ionization. The ionization probability is maximum when the energy difference between the ground state and the the higher value of the interatomic barrier and outatomic Coulomb barrier is minimum. The classical calculation offers a perspective to inspect the intriguing phenomena in quantum systems.
»

Partition and growth of convection patterns in Poiseuille-Rayleigh-Benard flow

null
Accept: 2016-08-18
Full Text: PDF (0KB) (19)
Show Abstract
In this paper, the Simple algorithm is used to numerically simulate the two-dimensional fully hydrodynamic equations. Partition of convection pattern , growth and the effect of horizontal flow on the characteristical parameters of different patterns in Poiseuille-Rayleigh-Benard flow are studied. The result indicated that flow zone is divided into three zones by the upper and lower critical Reynolds numbers , such as traveling wave zone, localized traveling wave zone, horizontal flow zone.and increase with reduced Rayleigh number. In the growth stage of the convection pattern, the growth process of three kinds of patterns with time is different, but the convection rolls grow all from downstream; Variation of characteristic parameters with time is also different, maximum vertical velocity and Nusselt number of traveling wave and localized traveling wave enter into the stable stage of the cycle variation after the exponential growth stage;and of horizontal flow pattern down to a stable constant after slow growth. and of three types of patterns decrease with increasing Reynold number, there are different rules in the different pattern areas. In this paper, formulas on variation ofandwith and formulas on variation ofandwithin different convection patterns are suggested.
More
Acta Physica Sinica
2019 Vol.68      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22
2018 Vol.67      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2017 Vol.66      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2016 Vol.65      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2015 Vol.64      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2014 Vol.63      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2013 Vol.62      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2012 Vol.61      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13      No.14      No.15      No.16      No.17      No.18
     No.19      No.20      No.21      No.22      No.23      No.24
2011 Vol.60      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2010 Vol.59      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2009 Vol.58      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13
2008 Vol.57      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2007 Vol.56      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2006 Vol.55      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2005 Vol.54      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2004 Vol.53      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2003 Vol.52      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2002 Vol.51      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2001 Vol.50      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
2000 Vol.49      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1999 Vol.48      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
     No.13
1998 Vol.47      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1997 Vol.46      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1996 Vol.45      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1995 Vol.44      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1994 Vol.43      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1993 Vol.42      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1992 Vol.41      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1991 Vol.40      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1990 Vol.39      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1989 Vol.38      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1988 Vol.37      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1987 Vol.36      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1986 Vol.35      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1985 Vol.34      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1984 Vol.33      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1983 Vol.32      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1982 Vol.31      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1981 Vol.30      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1980 Vol.29      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1979 Vol.28      No.1      No.2      No.3      No.4      No.5      No.6
1978 Vol.27      No.1      No.2      No.3      No.4      No.5      No.6
1977 Vol.26      No.1      No.2      No.3      No.4      No.5      No.6
1976 Vol.25      No.1      No.2      No.3      No.4      No.5      No.6
1975 Vol.24      No.1      No.2      No.3      No.4      No.5      No.6
1974 Vol.23      No.1      No.2      No.3      No.4      No.5      No.6
1973
1972
1971
1970
1969
1968
1967
1966 Vol.22      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9
1965 Vol.21      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1964 Vol.20      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1963 Vol.19      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1962 Vol.18      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1961 Vol.17      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1960 Vol.16      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8
1959 Vol.15      No.1      No.2      No.3      No.4      No.5      No.6
     No.7      No.8      No.9      No.10      No.11      No.12
1958 Vol.14      No.1      No.2      No.3      No.4      No.5      No.6
1957 Vol.13      No.1      No.2      No.3      No.4      No.5      No.6
1956 Vol.12      No.1      No.2      No.3      No.4      No.5      No.6
1955 Vol.11      No.1      No.2      No.3      No.4      No.5      No.6
1954 Vol.10      No.1      No.2      No.3      No.4
1953 Vol.9      No.1      No.2      No.3      No.4
1952
1951 Vol.8      No.1      No.2      No.3
1950 Vol.7      No.5      No.6
1949 Vol.7      No.4
1948 Vol.7      No.3
1947 Vol.7      No.1      No.2
1946 Vol.6      No.2
1945 Vol.6      No.1
1944 Vol.5      No.1      No.2
1943
1942
1941
1940 Vol.4      No.1
1939 Vol.3      No.2
1938
1937 Vol.3      No.1
1936 Vol.2      No.1      No.2
1935 Vol.1      No.3
1934 Vol.1      No.2
1933 Vol.1      No.1
物理学报
· Numerical simulation of soliton trapping of the supercontinuum in photonic crystal fiber [2012, No.12:124203-124203] (38728)
· Large-eddy simulation and experimental study of deflecting oscillation of planar opposed jets [2013, No.8:84704-084704] (38195)
· Effect of concentration of heavy oxygen vacancy in rutile and anatase (TiO2) on electric conductivity performance studied by simulation and calculation [2013, No.23:237101-237101] (30775)
· Quasiparticle band structure calculation for SiC using self-consistent GW method [2012, No.13:137103-137103] (29130)
· Proximity-effect-induced superconductivity by granular Pb film on the surface of Bi2Te3 topological insulator [2013, No.16:167401-167401] (27142)
Copyright © Acta Physica Sinica
Address: Institute of Physics, Chinese Academy of Sciences, P. O. Box 603,Beijing 100190 China
Tel: 010-82649294,82649829,82649863   E-mail: aps8@iphy.ac.cn