Formulation for shielding effectiveness analysis of a rectangular enclosure with an electrically large aperture
Robust visual tracking algorithm based on bidirectional sparse representation
Self-mixing interference effect based on fiber laser
Effect of curve groove on the spectral resolution for soft X-ray holographic flat-field gratings
The soft X-ray spectrograph is an important instrument for plasma diagnostics. As the core optical element of spectrograph, holographic flat-field grating is fabricated by aspheric wave-front recording optics, so grooves on the surface are curve. The curve grooves of the grating would affect the spectral image properties, thus influencing spectral resolutions. In the design of recording optics, only the groove density distribution on the surface in meridian line should be guaranteed, so optimized recording optics is not unique. Thus gratings with different curvatures of grooves but with expected groove density distribution could be obtained. For holographic flat-field gratings used in a 0.8-6 nm region, we analyze the influences of different curve grooves on the spectral image by ray tracing, and find that the almost straight grooves which are obtained by means of cylinder mirror can obtain the better spectral images. The theoretical results show that the spectral resolutions of grating with almost straight grooves are obviously improved compared with curve grooves, the theoretical spectral resolutions increase from 626 to 953 at 3 nm and from 635 to 1222 at 5 nm, respectively.
A molecular dynamics study on adhesive contact processes of surfaces with nanogrooves
The adhesive contact processes between a rigid spherical tip and substrates with nanogrooves of different sizes have been investigated with a large-scale molecular dynamics simulation method. Influences of the surface grooves on the load-displacement curves, the attractive forces in the loading/unloading processes, and material transfer have been discussed. Results show that compared with the contact between a tip and a smooth surface, the attractive force range becomes larger in the loading process, accompanied by several jumps of the load, and the maximum attractive forces both in the loading and unloading processes are smaller. When the groove depths are the same, the maximum attractive forces in the loading and unloading processes decrease gradually with the increase of the groove width. However, when the groove width becomes close to the contact diameter between the tip and the smooth surface, the maximum attractive force would increase slowly, tending to be close to the case of smooth surface. When the groove width is kept the same, the maximum attractive force in the loading process decreases with the increase of the groove depth, while the maximum attractive force in the unloading process is almost unchanged.
Deformation behaviors of zircaloy-4 alloy under uniaxial compression
Study on the influence of γ -ray total dose radiation effect on the threshold voltage and transconductance of the strained Si p-channel metal-oxide-semiconductor field-effect transistor
Molecular dynamics simulation on thermal conductivity of nanocomposites embedded with fractal structure
First-principles study on the effect of Ge-doping on the conductivity of InI
First-principles study on the effects of Zn-segregation in CuΣ5 grain boundary
Effect of oxygen implantation on microstructural and optical properties of ZnTe:O intermediate-band photovoltaic materials
First-principles study on stability and electronic properties of MC and Mn+1ACn phases
Study on the strained SiGe p-channel metal-oxide-semiconductor field-effect transistor with polycrystalline silicon germanium gate threshold voltage
Dwell time and escape tunneling in InAs/InP cylindrical quantum wire
Modeling on drain current of high-k gate dielectric fully-depleted nanoscale germanium-on-insulator p-channel metal-oxide-semiconductor field-effect transistor
A dual-trench silicon on insulator high voltage device with an L-shaped source field plate
Preparation and force-sensitive properties of carbon nanotube/polydimethylsiloxane composites films
Study on single crystal MgB2 nanosheets grown by hybrid physical-chemical vapor deposition
Magnetic and transport properties of bilayered perovskite manganites (La0.8Eu0.2)4/3Sr5/3Mn2O7
Fe/Cr doping effects on the magnetism in charge-ordered manganite La0.4Ca0.6MnO3
Subwavelength focusing of cylindrical vector beams by plano-concave lens based on one dimensional metallic photonic crystal
Thermochromic properties of W-doped VO2/ZnO nanocomposite films with flower structures
Study on the effect of delayed recovery of extracellular potassium ion concentration on spiral wave
Anomalous diffusion in the formation of Turing pattern for the chlorine-iodine-malonic-acid system with a local concentration depended diffusivity
Design of gradient coils on super-elliptical cylindrical surfaces
Analysis of information entropy of DC-DC converter
Investigation and suppression of pulse shortening problem caused by non-working mode self-excitation in an S-band long pulse relativistic klystron amplifier
Research on the beam-wave interaction theory of folded waveguide traveling wave tubes based on three-port network model
Theoretical and simulation study of 0.14 THz fundamental mode multi-beam folded waveguide traveling wave tube
X-band high power microwave combination technology based on the off-axis relativistic klystron amplifiers
Correction of migration through resolution cell in bistatic inverse synthetic aperture radar in the presence of time-varying bistatic angle
Design of the static var compensator adaptive sliding mode controller considering model uncertainty and time-delay
Hole quantization and conductivity effective mass of the inversion layer in (001) strained p-channel metal-oxid-semiconductor
Within the framework of k · p perturbation theory, models of the hole quantization and conductivity effective mass for the inversion layer in uniaxially tensile/compressive and Si-based baixially strained p-channel metal-oxid-semiconductor (PMOS) have been established. Results show that: 1) uniaxially compressive technique should be chosen for the carrier mobility enhancement in uniaxially strained PMOS; 2) the magnitude of uniaxial stress will be less than that of the biaxial case to improve PMOS performance using strained technique; 3) strained Si1-xGex is preferred to use instead of using strained Si, when we choose the biaxially strained materials for the PMOS channel. Our results can provide valuable references to Si-based and other strained device and materials design.
Study on intrinsic carrier concentration of direct bandgap Ge1-xSnx
Indirect bandgap Ge can be turned to a direct bandgap semiconductor by the alloy-modified technique, which can be applied to advanced photonic devices and electronic devices. Based on 8 bands Kronig-Penny Hamilton, this paper focuses on the physical parameters of direct bandgap Ge1-xSnx, such as conduction band effective density of states, valence band effective density of states and the intrinsic carrier concentration, and aims to provide valuable references for understanding the direct bandgap modified Ge materials and device physics as well as their applications. Results show that: conduction band effective density of states in direct bandgap Ge1-xSnx alloy decreases obviously with increasing Sn fraction, while its valence band effective density of states almost does not change with increasing Sn fraction. Compared with bulk Ge, the conduction band effective density of states and valence band effective density of states in direct bandgap Ge1-xSnx alloy are lower by two and one orders of magnitude respectively; the intrinsic carrier concentration in direct bandgap Ge1-xSnx alloy increases with increasing Sn fraction, and its value is an order of magnitude higher than that of bulk Ge.
Research on the light emitting diode array launching performance for indoor visible light communication
A kind of illumination calculation of array antenna composed of light emitting diode (LED) source based on Lambert radiation model is proposed. This paper puts emphasis on the optimal design for the transmitting antenna of indoor visible light communication. And it also analyzes the influence of the forms of the spatial distribution of the light source, the distance between light sources, and the angle between the center beam of light source and optical axis of the system, as well as the layer spacing of space distribution on illumination uniformity. A circular array antenna is superior to a rectangular array antenna containing the same number of light sources in illumination uniformity and stability of signal transmission, which may increase by 10%. As the distance between light sources and the angle between the center beams of light sources and optical axis keep increasing, the illumination uniformity of array antenna composed of LED source increases first and then starts to drop. As a result, there exist the optimal values in the distance and the angle respectively. Illumination uniformity increases with the decrease of the distance of space distribution. The optimal value of design parameter of transmitting antenna array in a common room has been given, therefore, it optimizes launch performance, saves as much as 13% the number of light source and reduces the cost. These studies for the design of the transmitting antenna system provide a theoretical basis and practical values.
On dynamic information theory
In this paper, the author presents an overview on his own research works. In recent ten years, we extended the present static statistical information theory to dynamic processes and established a dynamic statistical information theory whose core is the dynamic information evolution equation describing the evolution law of dynamic information. Starting from the idea that the state variable probability density evolution equations of the stochastic dynamic system, the classical and quantum nonequilibrium statistical physical systems obeying stochastic law and the electrodynamic system obeying decterministic law can be regarded as their information symbol evolution equations and the definitions of dynamic information and dynamic entropy, we derived the evolution equations of dynamic information and dynamic entropy that express the evolution laws of dynamic information. These show that for the dynamic systems obeying a stochastic law, the time rate of change of dynamic information densities originates from their drift, diffusion and dissipation in state variable space inside the systems and coordinate space in the transmission processes, and that the time rate of change of dynamic entropy densities is caused by their drift, diffusion and production in state variable space inside the systems and coordinate space in the transmission processes. For the dynamic systems obeying the deterministic law, the evolution equations of dynamic information and dynamic entropy are the same mathematical type as the former except that dynamic information (entropy) density only has drift in state variable space inside the systems. Information and entropy have been connected with the state and change law of the system. Information diffusion and information dissipation occur at the same time. When the space noise can be neglected, information wave will appear. If we only consider the information change inside the systems, the dynamic information evolution equations reduce to information equations corresponding to the dynamic equations which express evolution laws for the above dynamic systems. This reveals that the evolution laws of the respective dynamic systems can be expressed by information equations in a unified fashion. Furthermore, we have presented the formulas for drift and diffusion information flow, information dissipation rate, and entropy production rate and a unified information expression for degradation and self-organizing evolution. Obtained the dynamic mutual information and dynamic channel capacity reflecting the dynamic dissipative character in transmission process, in when in the limiting case the ratio of channel length to signal transmission rate approaches zero, reduces itself to the present static mutual information and static channel capacity. All these new theoritical formulas and results are derived from the dynamic information evolution equation.
New infinite sequence complexion soliton-like solutions of (2+1)-dimensional Zakharov-Kuznetsov modified equal width equation
The (G'/G)-expansion method is further studied, the solution to the second-order nonlinear auxiliary equation is changed into solving of one unknown quadratic equation and Riccati equation by two function transformations. An infinite sequence solution of auxiliary equation is obtained with the help of Bäcklund transformation of Riccati equation and nonlinear superposition formula of the solution. In this way, the infinite sequence solution to the nonlinear evolution equation can be obtained by the (G'/G)-expansion method, this method is an extension of existing methods, which can get more infinite series solutions. Take the (2+1)-dimensional Zakharov-Kuznetsov modified equal width equation as an example to obtain the new infinite sequence solution. This method can be used to get the infinite sequence solution to other nonlinear evolution equations.
Synchronization control for a class of tele-operation system with stochastically time-varying communication delays
Synchronization control methods for a class of tele-operation system with stochastically time-varying communication delays are surveyed, aiming at the existing communication delays, packet loss, and so on, during the ground-based tele-operation of unmanned aerial vehicles. A control model for this class of master-slave tele-operation system with communication time delays is established. Then, the time delays within the remote control communication network are depicted by a time-varying-delay function, of which the modal parameters are transferred based on an ergodic Markov process. After that, the synchronization control problem of the system is solved by stability analysis of the mean square within the framework of the stochastic systems. Finally, the semi-physical simulation platforms of an unmanned micro-quadrotor are carried out to verify the methods presented in this paper; and the elementary simulation results show that the loci of the master-slave sides are all bounded through designing the controllers by the feedback linearization separately in the methods.
Research on drought in southwest China based on the theory of run and two-dimensional joint distribution theory
Based on the standardized precipitation index data of 89 meteorological stations in southwest China (Sichuan Province, Yunnan Province, Guizhou Province, Chongqing) during 1961-2010, the probability and interval time were analyzed by employing the theory of run and the Copula function. The droughts with duration less than 4 months and the severity less than 3 account for 80% of all the droughts in southwest China. Drought types are mainly light within a month, moderate within a month, severe within a season and severe within inter-seasons. The frequency of occurring of drought with a duration less than 3 months and the severity less than 1 is higher in the eastern and western areas, and the central region has higher frequencies of occurrence of drought with a duration greater than 3 months and with severity greater than 1.5. Return periods of drought in eastern and western areas are longer than that of central region. More obvious spatial difference appears with longer duration and greater severity. The probability differences of the same drought type in different climatic types are within 0.05, indicating that there is no wide-range fluctuation in the occurrence probabilities of all the drought types as the time goes on.
Approximate analysis of spatial fading correlation for multiple antenna system
Spatial fading correlation (SFC) mainly depends on power azimuth spectrum (PAS) of arrival signals and the transceiver mode of multi-antenna arrays. This paper investigates in depth the approximate algorithm and its complexity in SFC of multi-antenna arrays in a mobile communication system. First, we derive the closed-form formulas for SFCs under three typical PAS: i. e. a uniform distribution, a Gaussian distribution and a Laplace distribution. Based on these theoretical formulas, we study the approximate algorithm when the angle spread in PAS for arrival signals is small. From this, we develop a multi-antenna reception channel model and analyze in detail the impact of the antenna array and electric wave propagation parameters we choose on the capacity of multiple-input multiple-output (MIMO) channel. By using theoretical calculations and simulation experiments, we find that in a particular situation the approximate algorithm provides a good approximation for SFC. Furthermore, a method is used to quantify the applicability and calculation efficiency while analyzing the MIMO multi-antenna array. Finally, it can be concluded that the approximate method has a good approximation in particular situations, and it will greatly reduce the theoretical computational complexity. The method we suggest will improve the efficiency of analyzing and simulating a complex MIMO multi-antenna system.
Numerical simulation of heat transfer in gas-particle two-phase flow with smoothed discrete particle hydrodynamics
Heat transfer between particles and that between gas phase and particle phase in gas-particle two-phase flow cannot be ignored. Smoothed discrete particle hydrodynamics, as a new method for solving the gas-particle two-phase flow, has been used in simulating the aerolian sand transport successfully. Based on the smoothed discrete particle hydrodynamics method, a heat conduction model is presented in this paper and is used to simulate the heat transfer processes and the particle evaporation in gas-particle two-phase flow. Firstly, the equations to be solved are presented in which the energy equations are introduced for each phase and the second derivative item in conduction is treated by combining a standard smoothed particle hydrodynamics first derivative with a finite difference approximation of a first derivative. The heat conduction between particle and gas is computed from temperature difference and heat transfer coefficient. The disc-type particle cluster problem and bubble fluidized bed are simulated and the results are in close agreement with the two fluid model simulation results. The vaporization law for discrete phase droplet is used to deal with the particle evaporation and then a jet evaporation is simulated. Numerical results all show a good agreement with the discrete particle model results. It is indicated that the new method is of good accuracy and practical applicability.
Generalized dislocated lag projective synchronization of fractional chaotic systems with fully uncertain parameters
In order to improve the security of secure communication combined with the generalized dislocated projective synchronization and lag projective synchronization, a new generalized dislocated lag projective synchronization (GDLPS) is investigated. This paper takes the fractional order Chen system and Lü system as examples. for the parameters of the two systems are uncertain, based on the fractional stability theory and adaptive control method, the nonlinear controller and parameter update laws are designed for the GDLPS between the two chaotic systems with uncertain parameters. Under the controller and parameter update laws, GDLPS of the two uncertain parameters chaotic systems is achieved and all uncertain parameters of the drive system and response system are identified. Theoretical analyses and numerical simulation show that this method is feasible and effective.
Research on synchronous method for photovoltaic supplied micro-grid based on small-world network model
Based on the solution to the strictly piecewise linear state equation of a photovoltaic (PV) supplied micro-grid inverter, the nonlinear dynamic behavior of PV supplied micro-grid inverter is analyzed in this paper, and each PV supplied micro-grid inverter is considered as a network node, then a synchronous method for PV supplied micro-grid is studied using the small-world network model. Studies have found that, compared with the nearest-neighbor coupling network model, the PV supplied micro-grid based on the small-world network model has a faster synchronization time, and also has a faster recovery time in case of plus disturbance.
Direct transport of fractional overdamped deterministic motors in spatial symmetric potentials driven by biharmonic forces
Physical significance of fractional damping for order 0< p <2 is demonstrated from the perspective that it can be explained as the memory of acceleration. Based on Caputo's fractional derivatives, the transport phenomenon of fractional overdamped deterministic motors in spatial symmetric potentials driven by biharmonic forces is investigated numerically. Relationships between transport velocity and model parameters are analyzed. The effect of fractional order is discussed in detail. Research shows that the contribution of historical acceleration increases or decreases monotonously with the historical moment varying with different fractional orders. With certain parameters the transport velocity can show generalized resonance when the spatial potential depth or the external force frequency varies. Furthermore, for some large orders, the velocity varies in step with the variation of potential depth and is in a direct proportional to the frequency if there is transport. Effect of fractional damping is intimately linked with the shape of the force. The memory of damping force can promote or inhibit the particle transport under different conditions, thus triggering abundant transport behaviors.
Analysis on spherical conformal microstrip antenna array by characteristic basis function method
The ab initio and potential energy curve of SiF2(1A1)
Structure and stability of Ti2Bn (n=1-10) clusters: an ab initio investigation
Effect of Pd in NiTi on the martensitic transformation temperatures and hysteresis: a first-principles study
Isotope effect of trihydride aluminum oxide
Study on the photodetachment of H- ion near a dielectric sphere
Vector analysis of the coherent anti-Stokes Raman scattering signals generated under the tightly focused condition
A segmentation calculation method for plasma collision frequency considering the electro-magnetic wave driving effect
Characterization of plasma in a short-tube helicon source
Experimental investigation on the influence of the dopant ratio on ablative Rayleigh-Taylor instability growth
Plasma-based multistage virtual cathode radiation
Laser shadowgraphy diagnostics for insulated-ordinary mixed planar wire array Z pinches
Research on attaining methods of rainfall "truth" by assessment of radar measurement of rainfall
Characteristics of winter-to-winter recurrence of atmospheric temperature in the northern area of East Asia
A new sampling method based on radiation energy density for location of radiative source particles
Research on the optical variability of oscillating disk