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Chinese Physics B 2009年第12期18卷 5534-5538页

作者：李敏米贤武 college of Physics Science and Information Engineering Jishou University

This paper studies both the intraband polarization and terahertz emission of a semiconductor superlattice in combined dc and ac electric fields by using the superposition of two identical time delayed and phase shifted optical pulses. By adjusting the delay between these two optical pulses, our results show that the intraband polarization is sensitive to the time delay. The peak values appear again for the terahertz emission intensity due to the superposition of two optical pulses. The emission lines of terahertz blueshift and redshift in different ac electric fields and dynamic localization appears. The emission lines of THz only appear to blueshift when the biased superlattice is driven by a single optical pulse. Due to excitonic dynamic localization, the terahertz emission intensity decays with time in different dc and ac electric fields. These are features of this superlattice which distinguish it from a supertattice generated by a single optical pulse to drive it.

关键词： density matrix theory semiconductor superlattice terahertz emission

Relativistic multichannel treatment of autoionization Rydberg series of 4s^2nf(n=4-23)J~π=(7/2)° for scandium

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Chinese Physics B 2008年第6期17卷 2027-2032页

作者：贾凤东王京阳钟志萍 college of Physical Sciences Graduate University of the Chinese Academy of Sciences

Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf（n=4- 23）J^π -（7/2）° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf（n=4- 23）J^π -（7/2）° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2（^1G4） of Sc^＋.

关键词： relativistic multichannel theory multichannel quantum defect theory electron-electron correlations

A fast and practical method to pack spheres for mesh generation

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Acta Mechanica Sinica 2008年第4期24卷 439-447页

作者： Jianfei Liu Shuixiang Li Yongqiang Chen LTCS College of EngineeringPeking University Beijing 100871 China

Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods presented so far for mesh generation. The algorithm packs spheres inside a domain using advancing front method. High efficiency has resulted from a concept of 4R measure, which localizes all the computations involved in the whole sphere packing process.

关键词： Sphere packing· Front Sheltering operation ·Mesh sizing function Mesh generation

A Compact Implementation of AES S-Box Using Evolutionary Algorithm

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Chinese Journal of Electronics 2017年第4期26卷 688-695页

作者： LIU Yaoping WU Ning ZHANG Xiaoqiang ZHOU Fang GE Fen college of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics

S-Box based on Composite field arithmetic（CFA） technology is optimized by Genetic algorithm（GA）and Cartesian genetic programming（CGP） model for reducing the hardware complexity. After using the CFA technique to map Multiplicative inverse（MI） over GF（2～8）into composite field GF(（2～4）2), the compact MI circuit over GF（2～4） is selected from 100 evolved circuits, and same design method is applied to the compact multiplication circuit over GF（2～2）. Compared with the direct implementations, the areas of optimized circuits of MI over GF（2～4） and multiplication over GF(（2～2）2) are reduced by66% and 57.69%, respectively. The area reductions for MI over GF（2～8） and the whole of S-Box are up to 59.23%and 56.14%, separately. In 180 nm 1.8V COMS technology,compared to previous works, the S-Box proposed in this paper has the minimum area and minimum power, which are 11.27% and 6.65% smaller than that of the smallest area S-Box, respectively.

关键词： Advanced encryption standard(AES) Composite field arithmetic(CFA) S-Box Evolutionary al gorithm(EA)

Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

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Chinese Journal of Chemical Engineering 2018年第9期26卷 1785-1791页

作者： Baoqing Liu Yijun Zheng Ruijia Cheng Zilong Xu Manman Wang Zhijiang Jin Institute of Process Equipment College of Energy Engineering Zhejiang University

The effects of impeller type, stirring power, gas flow rate, and liquid concentration on the gas–liquid mixing in a shear-thinning system with a coaxial mixer were investigated by experiment, and the overall gas holdup, relative power demand, and volumetric mass transfer coefficient under different conditions were compared. The results show that, the increasing stirring power or gas flow rate is beneficial in promoting the overall gas holdup and volumetric mass transfer coefficient, while the increasing system viscosity weakens the mass transfer in a shearing–thinning system. Among the three turbines, the six curved-blade disc turbine(BDT-6) exhibits the best gas pumping capacity; the six 45° pitched-blade disc turbine(PBDT-6) has the highest volumetric mass transfer coefficient at the same unit volume power.

关键词： Non-Newtonian fluids Coaxial mixer Gas holdup Relative power demand Mass transfer

An experimental investigation of one-and two-degree of freedom VIV of cylinders

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Acta Mechanica Sinica 2013年第2期29卷 284-293页

作者： Zhuang Kang Lu-Sheng Jia college of Shipbuilding Harbin Engineering University CNOOC Research Institute

In the paper,an experiment investigation was conducted for one-and two-degree of freedom vortex-induced vibration（VIV） of a horizontally-oriented cylinder with diameter of 11 cm and length of 120 *** the experiment,the spring constants in the cross-flow and in-line flow directions were regulated to change the natural vibration frequency of the model *** was found that,in the one-degree of freedom VIV experiment,a ＂double peak＂ phenomenon was observed in its amplitude within the range of the reduced velocities tested,moreover,a ＂2T＂ wake appeared in the vicinity of the second *** the two-degree of freedom VIV experiment,the trajectory of cylinder exhibited a reverse ＂C＂ shape,i.e.,a ＂new moon＂ *** analysis of these data,it appears that,besides the non-dimensional in-line and cross-flow natural vibration frequency ratios,the absolute value of the natural vibration frequency of cylinder is also one of the important parameters affecting its VIV behavior.

关键词： One- and two-degree of freedom VIV “2T” wake “New moon” trajectory Natural vibration frequency ratio

Numerical Simulation of Tip Clearance Flow Passive Control in Axial Turbine

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Journal of Thermal Science 2008年第2期17卷 147-155页

作者： LI Wei QIAO Wei-yang XU Kai-fu LUO Hua-ling college of Propulsion and EnergyNorthwestern Polytechnical University Xi＇an 710072 China

This paper focuses on the effects of five different passive turbine tip clearance flow control methods on the tip clearance flow physics, which consists of a partial suction side squealer tip, a double squealer tip, a pressure side tip shelf with inclined squealer tip on a double squealer tip, a tip platform extension edge in pressure side and in suction side respectively. A pressure-correction based, 3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds Stress Model was adopted. The variable specific heat was considered. The detailed tip clearance flow field with different squealer rims was described with the streamline and the velocity vector. Accordingly, the mechanisms of five passive controls were elucidated; the effects of the passive controls on turbine efficiency and tip clearance flow field were illuminated. The results showed that the secondary flow loss near the outer casing including the tip leakage losses and the passage vortex losses could be reduced in all the five passive control methods. The turbine efficiency could be increased via the rational passive turbine tip clearance flow control. The Improved PS Squealer had the best effect on turbine efficiency, and the efficiency increased by 0.215%.

关键词： contact face wave receiving tube absorber

Input-to-state stability of Euler-Maruyama method for stochastic delay control systems

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Journal of Systems Engineering and Electronics 2013年第2期24卷 309-317页

作者： Shifang Kuang Feiqi Deng Yunjian Peng college of Automation Science and Engineering South China University of Technology

This paper develops the mean-square exponential input-to-state stability（exp-ISS） of the Euler-Maruyama（EM） method for stochastic delay control systems（SDCSs）.The definition of mean-square exp-ISS of numerical methods is *** conditions of the exact and EM method for an SDCS with the property of mean-square exp-ISS are obtained without involving control Lyapunov functions or *** the global Lipschitz coefficients and mean-square continuous measurable inputs,it is proved that the mean-square exp-ISS of an SDCS holds if and only if that of the EM method is preserved for a sufficiently small step *** proposed results are evaluated by using numerical experiments to show their effectiveness.

关键词： Euler-Maruyama(EM) method exponential inputto-state stability(exp-ISS) numerical solution stochastic delay control system(SDCS) time delay

Study on Static Deflection Model of MEMS Capacitive Microwave Power Sensors

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Chinese Journal of Electronics 2024年第5期33卷 1188-1195页

作者： Ye JIN Debo WANG college of Electronic and Optical Engineering & college of Flexible Electronics (Future Technology) Nanjing University of Posts and Telecommunications college of Integrated Circuit Science and Engineering Nanjing University of Posts and Telecommunications

In this paper, a static deflection model of MEMS cantilever beam is proposed, which can better study the force deformation of micro-electro-mechanical system(MEMS) cantilever beam and the output characteristics of capacitive microwave power sensor. The deflection curve is used to describe the deformation of the cantilever beam and then the overload power and sensitivity of this power sensor are derived. It is found that the overload power decreases with the beam length, and increases with the initial height of beam. The sensitivity increases with the beam length, and has a linear growth relationship with the measuring electrode width. A MEMS dual-channel microwave power sensor is designed, fabricated and measured. At a microwave signal frequency of 10 GHz, the sensitivity of the sensor is measured to be 0.11 V/W for the thermoelectric detection channel and 65.17 fF/W for the capacitive detection channel. The sensitivity calculated by the lumped model is 92.93 fF/W, that by the pivot model is 50.88 fF/W,and that by the deflection model proposed in this work is 75.21 fF/W. Therefore, the theoretical result of the static deflection model is more consistent with the measured result and has better accuracy than the traditional lumped model and pivot model.

关键词： Microwave measurement Micromechanical devices Microelectromechanical systems Sensitivity Voltage measurement Accuracy Deformation

A Finite Element Cable Model and Its Applications Based on the Cubic Spline Curve

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China Ocean Engineering 2013年第5期27卷 683-692页

作者：方子帆贺青松向兵飞肖化攀何孔德杜义贤 college of Mechanical & Material Engineering China Three Gorges University

For accurate prediction of the deformation of cable in the towed system, a new finite element model is presented that provides a representation of both the bending and torsional effects. In this paper, the cubic spline interpolation function is applied as the trial solution. By using a weighted residual approach, the discretized motion equations for the new finite element model are developed. The model is calculated with the computation program complier by Matlab. Several numerical examples are presented to illustrate the numerical schemes. The results of numerical simulation are stable and valid, and consistent with the mechanical properties of the cable. The model can be applied to kinematics analysis and the design of ocean cable, such as mooring lines, towing, and ROV umbilical cables.

关键词： tension stiffness bending stiffness torsion stiffness cubic spline curve Galerkin criterion finite element model