Extracting the harmonic signal from the chaotic interference background is very important for theory and practical application. The wavelet transform and empirical mode decomposition (EMD) have been widely applied to harmonic extraction from chaotic interference, but because the wavelet and EMD both present the mode mixing and are sensitive to noise, the harmonic signal often cannot be precisely s...
We study the problem of canonical quantization of classical scalar and Dirac field theories in the finite volumes respectively in this paper. Unlike previous studies, we work in a completely discrete version. We discretize both the space and time variables in variable steps and use the difference discrete variational principle with variable steps to obtain the equations of motion and boundary cond...
According to irradiation-reflection model, by combining the generalized bounded operation model with guide filter, the problem of enhancement for multispectral degraded images with blurred details can be effectively solved and the contrast and low signal-to-noise ratio can be improved. The multi-scale reflection component image, i.e., final enhanced image is obtained through the following procedur...
The cohesiveness of autonomous cooperative system is the basis of achieving the effective communication and cooperation among the multiple vehicles. Therefore, the biosphere mechanism of queen mandibular pheromone is used for reference in this paper, to abstract the macro motion characteristic of multiple unmanned aerial vehicles autonomous cooperative tracking system. Then, some Lyapunov function...
Based on the standardized precipitation index data of 89 meteorological stations in southwest China (Sichuan Province, Yunnan Province, Guizhou Province, Chongqing) during 1961-2010, probability model containing drought duration and drought severity is established by using the theory of run and the Copula function. The influences of the drought sample number on the distribution parameters, the pro...
For the mechanical analyses of the axisymmetric structures in civil and mechanical engineering, combining the interpolating reproducing kernel particle method and the principle of minimum potential energy of space axisymmetrical elastic problems, the interpolating particle method for space axisymmetrical problem of elasticty is presented. And the corresponding matrix equations are deduced. This me...
Radio acoustic sounding system (RASS) is a detection technique using the interaction between radio wave and acoustic wave to remotely measure vertical profiles of the atmospheric temperature, and usually composed of a Doppler radar with fixed beam (monostatic or bistatic) and an acoustic source with high power. By combining acoustic propagation equation and radio wave propagation equation in a dis...
Noise, which is ubiquitous in real systems, has been the subject of various and extensive studies in nonlinear dynamical systems. In general, noise is regarded as an obstacle. However, counterintuitive effects of noise on nonlinear systems have recently been recognized, such as noise suppressing chaos and stochastic resonance. Although the noise suppressing chaos and stochastic resonance have been...
The traditional digital imaging of neutron radiography is based on neutron scintillation screen cooperated with charge coupled device (CCD) camera, whose spatial resolution and neutron detection efficiency are contradictory. Neutron detection method based on microchannel plates (MCP) could solve the problem appearing in traditional method. It could supply high spatial resolution, high neutron dete...
Fusion reactor is considered as one of the solutions for the sustaining development of nuclear energy. International Thermonuclear Experimental Reactor (ITER) is the biggest fusion reactor research plan in the world. High-intensity D-T fusion neutron generator can generate 14 MeV neutrons, and it matches the neutrons generated in ITER and be competently used for imitating the neutron environment i...
Sympathetic cooling is one of the most promising techniques for producing ultracold molecules from precooled molecules. The previous work has shown that it is inadequate to use the ultracold alkali-metal atoms as coolant for sympathetic cooling. Whether the ultracold alkali-earth-metal atoms can be used as coolant deserves to be investigated. In this paper, the cold collision dynamic behaviors for...
For α-boron, R3m group, Lennard-Jones (L-J) pair potential function is fitted, and a pairwise many-body potential is constructed. For constructing both interatomic potentials, only the atomic average cohesive energy and geometric information are needed. And the cohesive energy and geometry of α-boron crystal are calculated by first-principles code Castep. The fitting procedure for the potentials i...
ELECTROMAGENTISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
The underwater visibility is very important in underwater vision research and target detection. However, most underwater vision systems cannot guarantee to possess the performance under complex water conditions. This is because underwater images are usually degraded by light-water interactions of absorption and scattering. The ambient light is scattered into the cameras line of sight by water mole...
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
To obtain the base data for insulation design of the electrical equipment used in the high temperature gas cooled reactor nuclear power plant, an experimental apparatus for testing helium insulation property under high pressure is designed. The apparatus is composed of a pressure vessel, a heating system, an electrical penetration assembly, a vacuum pump, a pressure gauge, a safety pressure valve,...
Backward Raman amplification (BRA) in plasma can be used for generating ultra-powerful laser pulses. In this paper, the plasma density effect on backward Raman laser amplification is studied by using particle-in-cell method. It is found that using a low plasma density can lead to the premature Langmuir wave breaking and thus result in a small energy-transfer efficiency. On the other hand, using a ...
Shock wave is a common phenomenon in astrophysics. Shock wave acceleration has been regarded as a source of high-energy cosmic rays. Very strong magnetic field exists in the surrounding of the shock wave at the edge of the supernova remnants. But the mechanisms of generation and amplification of such a strong magnetic field are not clear yet. In this paper, the properties of shock wave driven by t...
In this paper, the interaction between the low energy proton ring-beam with an initial velocity perpendicular to the background magnetic field, and the background plasma is studied by one-dimensional (1D) hybrid simulations. In the initial stage, the excited plasma waves experience a fast growth exponentially, which is consistent with the linear theory. After that, three non-linear stages, includi...
Air corona discharge ionic wind exciter can generate driving force without any rotating component, which makes it commonly used in aviation and aerospace field. Although there are many explanations of the thrust generating mechanism of the air corona discharge ionic wind exciter, no existing theories can unify the experiment results obtained under various conditions. A further study is still neede...
With the slow effect of electric field of thundercloud, a kind of positive glow corona without streamers is initiated from the surface of object near the ground, and a large number of positive space charges are injected into the surrounding space, consequently, lighting targets selected by the lighting leader can be changed. In this paper, a numerical simulation of positive glow corona discharge i...
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
The thermal-stability and melting mechanism of the Ag nanocrystalline in the process of high-temperature relaxation are investigated with embedded atomic method and molecular dynamics simulations. The dynamic evolution of the crystalline’s morphology is revealed based on the analyses of mean square displacement and lifetime of the stability. It is concluded that there are obviously anisotropic beh...
Spray forming is a kind of near-net-shaped rapid solidification process based on powder metallurgy gas atomization technology. In this work, the FGH4095M is fabricated by spray forming. The pre-alloy is prepared by vacuum induction melting and vacuum arc remelting techniques. Then the alloy is sprayed by SK2 facility with atomization gas nitrogen at University of Bremen in Germany. In this paper w...
Shock and release experiments are performed on the porous Sn with sub-micropores with porosity m=1.01. Time-resolved interfacial velocities between the porous Sn and LiF window are measured with Doppler pins system under seven pressure points from 31.8 GPa to 66.1 GPa. From the interfacial velocity, the Euler longitudinal sound velocities and the bulk sound velocities are obtained. The correspondi...
A coaxial cylindrical heterojunction of carbon tubes, which consists of alternant bands of 5- and 7-membered rings, can be formed by one armchair (n, n) carbon nanotube and one zigzag (2n, 0) carbon nanotube. The torsional mechanical properties of this kind of (n, n)-(2n, 0) heterojunction constructed by the same length of armchair and zigzag nanotubes are studied by using molecular dynamics metho...
Structural kinetics in crystalline solids is driven heterogeneously at an atomic level by localized defects, which in turn drive mesoscopic and macroscopic phenomena such as structural phase transformation, fracture, and other forms of plastic flows. A complete description of such processes therefore requires a multiscale approach. Existing modeling methods typically operate exclusively either on ...
Grain boundary (GB) research is always the most fundamental and active study field in interface science. Grain boundary premelting (GBPM) is induced as a consequence of local inner strain around defects in material at high temperature. When GB premelting is under an external stress, it is referred to as stress induced GBPM (SIGBPM). Owing to the fact that the width of a GB usually is a few atoms t...
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
In a semi-infinite crystal, the periodic potential is destroyed at the surface, and the electronic wave functions exponentially decay from the surface to both sides. Such localized electronic states in the vicinity of the surface are known as Tamm surface states. In analogy to the electronic Tamm states, in recent years, optical Tamm states have been found at the surface of the truncated photonic ...
Recently, magnonic crystals which are the magnetic counterparts of photonic crystals or phononic crystals are becoming a hot area of research. In this paper, band structure of two-dimensional magnotic crystal composed of square rods triangularly arranged are calculated by using the plane-wave expansion method. Spin-wave band structures of two-dimensional magnonic crystal composed of Fe triangularl...
In order to study how the ingredient, sintering temperature, oxygen, doping and other conditions affect magnetic properties of strontium ferrite powder, a strontium ferrite powder is prepared by sol-gel method, and a new method of studying magnetic properties of strontium ferrite powder based on an electron paramagnetic resonance (EPR) is established in this paper. The sintered samples are tested ...
Many GaInN light-emitting diodes (LEDs) are subjected to a great temperature variation during their serving. In these applications, it is advantageous that GaInN LEDs have a weak temperature dependence of forward voltage. However, the factors determining the exact temperature dependence of the forward voltage characteristics are not fully understood. In this paper, two series of GaInN LEDs are pre...
We use a density-matrix renormalization group method to study quantitatively the phase diagram of the half-filled one-dimensional (1D) extended Hubbard model in the presence of a staggered ionic potential Δ. An extensive finite-size scaling analysis is carried out on the relevant structure factors and localization operator to characterize the Mott-insulator (MI)-bond-ordered insulator (BOI)-band-i...
We theoretically investigate the effects of electronic correlations (including spin and Coulomb correlations) on the magnetotransport through a parallel double quantum dot (DQD) coupled to ferromagnetic leads. Two dots couple coherently through electron correlations, rather than tunneling directly between two dots, and each dot is coupled to two semi-infinite ferromagnetic leads. We assume that th...
Since the topological insulator was discovered, the investigation of topological properties has become the hot spot in condensed matter physics. In this paper, we study topological properties of chalcogenide compounds Ge2X2Te5 (X=Sb, Bi) crystals and their monolayer and bilayer films as well as the vertical uniaxial pressure induced topological quantum phase transitions in monolayer and bilayer fi...
First-principles calculation is a quite powerful tool for explaining experimental phenomena and predicting the properties of new materials. Based on the first-principles calculation within the density functional theory, the energetic stabilities and electronic properties of Mg and Si doped GaN/AlN superlattices with wurtzite and zinc-blende structures are investigated. The results show that there ...
The development of high-performance integrated circuit chips and the shrinkage of feature sizes according to Moore’s law bring forward continuously the requirements for low dielectric constant (low-k) materials with various excellent properties in the back-end-of-the-line (BEOL) interconnect. Porous SiCOH films prepared by plasma enhanced chemical vapor deposition (PECVD) through a porogen approac...
In order to optimize the performance of the coupled resonator optical waveguide (CROW) gyroscope, a well-designed structure by optimizing the ring number and the transmission coefficient of the coupler is used as the core component of the planar waveguide optical gyroscope. The structure with double coupled ring resonator may possess large effective group refractive index to enhance angular sensin...
Eu3+ doped CaMoO4 micron phosphors of different concentrations were prepared by chemical precipitation method. The photoluminescence properties were studied in detail. The X-ray diffraction measurements indicate that the samples are scheelite structure, and doping Eu3+ enlarge the lattice parameter of host material. The scanning electron microscope images show that the particle morphology is near-...
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
Precious metals exhibit fascinating properties and extensive applications in chemical engineering, high-temperature measurement, and electronic industry. The microstructures of these metals are generally polycrystalline and the precious metals like Ir and Ru with polycrystalline microstructures are difficult to deform at room temperature. However, the single crystal of precious metal can be well d...
The substrate of as-cast Ni-28 wt% Sn hypoeutectic alloy immersed in liquid nitrogen is rapidly remolten and solidified by laser surface remelting with a scanning velocity of 10 mm/s and the laser power of 1950 W. The microstructure of the substrate and its effect on the microstructure of the molten pool are investigated by scanning electron microscope carefully. It is found that the substrate of ...
Li-ion battery is a complicated distributed parameter system that can be described precisely by field theory and partial differential equations. In order to reduce the calculation amount and the solution difficulty, a distributed parameter system is often described by ordinary differential equation model during the design and the analysis. As a result, systemic error is caused, and the reliability...
Based on the standard linear solid model, the solutions in Laplace domain, such as particle velocity v, particle displacement u, radial stress σr, tangential stress σθ, radial strain εr, tangential strain εθ, reduced velocity potential γ (RVP), and reduced displacement potential ψ (RDP), are derived from the spherical wave equations. The propagating characteristics of these physical quantities, as...
Phase-shift full-bridge (PSFB) DC-DC converter benefits from high efficiency by zero-voltage switching turn-on of all switches without any additional auxiliary circuit, and PSFB DC-DC converter has been widely used in high power applications. In this paper, the operating mode of PSFB DC-DC converter is studied, and the energy iteration model of PSFB DC-DC converter is established. The discrete pha...
The sheet beam klystron is a kind of novel powerful microwave and millimeter-wave vacuum electron device, in which used is a thin rectangular sheet beam with high aspect ratio in order to improve beam-wave interaction efficiency by improving space-charge-limiting current of electron beam and obtaining big electric current, and it has many actual and potential applications. Based on the motion of t...
Due to the excellent characteristics of field-effect transistor and its high absorption coefficient in the visible region, pentacene has been widely used in phototransistors. The channel length of the vertical transistor could be designed to be very short (on the order of nanometers). In this way, the device performances and its working frequency can be effectively improved, and the energy consump...
Cortical cortex is mainly composed of excitatory and inhibitory neurons. Balance between excitation and inhibition is a ubiquitous experimental phenomenon in brain. On the one hand, balanced excitation and inhibition plays a crucial role in maintaining normal brain functions; on the other hand, the loss of balance between the two opposing forces will cause neural diseases, such as epilepsy, Parkin...
In this work, the composite anode of BCP/Ag replaces the composite anode of Ca/Al, and the PTB7:PC71BM acts an as active layer for polymer solar cells. Calcium (Ca) is not a desirable candidate as electron extraction layer (EEL) for long-term stability polymer solar cells (PSCs) on account of its nature of active metal. And then, due to the poor stability of Al, which is not a desirable candidate ...
In this paper, the basic laws of spectral response, open-circuit voltage and short circuit current of GaAs/Ge solar cells are obtained by ground simulation irradiation test under the different-energy electrons’ irradiations, such as 1, 1.8 and 10 MeV. The carriers’ transport mechanism in cells is analyzed using the PC1 D simulation program. The variations of the majority carriers’ concentration an...
A three-dimensional (3D) numerical analysis model of tungsten inert gas welding arc interacting with an anode material is presented based on the local thermodynamic equilibrium assumption and taking the behavior of metal vapor into account. The thermodynamic parameters and transport coefficients of plasma arc are dependent on the local temperature and metal vapor concentration. A second viscosity ...
This study deals with the case of multiple internal heat source inversion problem of steady-state based on nondestructive infrared detection. We construct homogeneous and heterogeneous steady heat conduction models of different shapes. Neither the number of heat sources, nor their locations, nor their sizes nor their intensities are known. We use the finite element method (FEM) based on numerical ...
Fluorescence resonance energy transfer (FRET) is non-radiation energy transfer that occurs between a donor (D) molecule in an excited state and an acceptor (A) molecule in a ground state by dipole-dipole interactions. The efficiency of FRET is dependent on the extent of spectral overlap between the donor photoluminescence peak and the absorption spectrum of acceptor, the quantum yield of the donor...
A class of single tooth-shaped plasmonic filter based on graphene nanoribbon is proposed in this paper, and the structure is numerically analysed by using finite-difference time-domain method. The tooth-shaped structure of graphene nanoribbon can induce a sharp band-stop effect in the transmission spectrum, and the filtering characteristics can be analysed by the scattering matrix method. The effe...
Cognitive radio can significantly improve spectrum efficiency by temporarily sharing under-utilized licensed frequency with primary users. Its spectrum management framework consists of four parts: spectrum sensing, spectrum decision, spectrum sharing and spectrum handoff. The last part is what we focus on in this paper. Spectrum handoff, which aims at guaranteeing requirement for service of second...
Low frequency noise in the partially depleted silicon-on-insulator (SOI) NMOS device is investigated in this paper. The experimental results show low frequency noise behaviors are in good consistence with classical noise model. Based on McWhorter model, the low frequency noise in the SOI device results from the exchange of carriers between channel and oxide. The densities of trapped charges in the...
According to the completeness theory of circuit, Chua [Chua L O 1971 IEEE Trans. Circ. Theor. 1971 18 507] put forward the fourth basic circuit element memristor besides resistor, inductor and capacitor in 1971. And memorisistance is defined as the ratio of the flux to the charge passing through it. With the emergence and development of nanoscale semiconductor technology, HP laboratoty successfull...
Graphene plasmons have aroused a great deal of research interest in recent years due to their unique features such as electrical tunability, ultra-strong field confinement and relatively low intrinsic damping. In this review paper, we summarize the fundamental optical properties of localized and propagating plasmons supported by graphene, and the experimental techniques for excitation and detectio...
The effect of gas bubble on acoustic characteristic of sediment is important for ocean science, ocean geology, ocean geophysics, etc. Twenty five samples of ocean bottom sediments are extracted through gravity sampling equipment from the East China Sea and are sealed in PVC pipes for storage in order to study the effect of gas bubble on acoustic characteristic of sediment. In order to obtain the g...