bluuebunny/crossref_metadata_2025 huggingface dataset:
A dual-trench silicon on insulator high voltage device with an L-shaped source field plate
Authors: Shi Yan-Mei  , Liu Ji-Zhi  , Yao Su-Ying  , Ding Yan-Hong  , Zhang Wei-Hua  , Dai Hong-Li  ,   School of Electronics Information Engineering, Tianjin University, Tianjin 300072, China;,   School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384, China;,   School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

To improve the breakdown voltage and reduce the specific on-resistance of a small size silicon on insulator (SOI) device, a dual-trench SOI high voltage device with an L-shaped source field plate is proposed. The device has the features as follows: first, a trench gate is adopted. The trench gate widens the current conduction area and makes the current conduction path shorter, thus lowering the specific on-resistance. Second, a SiO2 dielectric layer is introduced into the drift region. This dielectric layer can hold a high electric field, which makes the breakdown voltage greatly increased. Third, an L-shaped source field plate is introduced. This field plate modulates the electric field in the drift region, so increases the optimized doping concentration of the drift region significantly and reduces the specific on-resistance. The results from the two-dimensional semiconductor simulator show that as compared with a conventional SOI device at the same cell pitch, the breakdown voltage is increased by 151%, and the specific on-resistance is reduced by 20%. The specific on-resistance is reduced by 80% at the same breakdown voltage. Compared with a dual-trench SOI device with the same cell pitch, the proposed device maintains the same high breakdown voltage as the dual- trench SOI device, and at the same time, the specific on-resistance is decreased by 26%.
Preparation and force-sensitive properties of carbon nanotube/polydimethylsiloxane composites films
Authors: An Ping  , Guo Hao  , Chen Meng  , Zhao Miao-Miao  , Yang Jiang-Tao  , Liu Jun  , Xue Chen-Yang  , Tang Jun  ,   Key Laboratory of Instrumentation Science and Dynamic Measurement (North University of China), Ministry of Education, Taiyuan 030051, China;,   State Key Laboratory of Science and Technology on Electronic Test and Measurement, North University of China, Taiyuan 030051, China
Published: December 2020

With the development of sensors, a study on carbon nanotube composites (CNT) used as force sensing elements is presented in this paper, which consists of carbon nanotubes with polydimethylsiloxane (PDMS) as a matrix. Nanocomposites of carbon nanotube and polydimethylsiloxane, CNT-PDMS with different filler concentrations have been successfully prepared via ultrasonic and mixed method. With different density, the electrical characteristics change as a function of the strain. The piezo-resistance and piezo-capacitance properties of these composites have been studied in detail. In our experiment, the gauge factor has reached 40 for piezo-resistance and 70 for piezo-capacitance. It is shown that there is an effective and reliable way, which is to change the density of CNT-PDMS nanocomposites, to set the features to sensing strain and stress for resistance and capacitance of the composites. This nanomaterial has a decent potential in mechanical quantity sensors field.
Design of gradient coils on super-elliptical cylindrical surfaces
Authors: Wang Liang  , Cao Ying-Hui  , Jia Feng  , Liu Zhen-Yu  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100039, China;,   Department of Diagnostic Radiology, Medical Physics, University Medical Center Freiburg, Freiburg 79106, Germany
Published: December 2020

A super-elliptical cylinder surface can shorten the distance between coils and target, enhance the space utilization, and enlarge the homogeneous imaging volumes. This paper proposes a method to design magnetic resonance imaging (MRI) gradient coils using the stream function and the developable property of the super-elliptical cylindrical surface. Based on the Biot-Savart law, the relationship between the magnetic flux density and stream function is established firstly, and the objective is chosen in the least-square form with the additional Tikhonov regularization term. Numerical accuracy of the magnetic flux density in the region of interest is maintained through transforming the cylindrical surface to the corresponding flat surface, and the value of regularization coefficient of the dissipated powers is chosen automatically by using the L-curve method. Via imposing specified boundary conditions to the stream function on the developed surface, the optimization of gradient coils is gained by directly solving well-posed linear algebraic equations. Numerical examples illustrate the feasibility of the proposed design method. The designed coils on the super-elliptical cylindrical surface show that the electric current and the dissipated powers are adequately optimized under the condition that the linear gradient deviation is less than 5%.
Investigation and suppression of pulse shortening problem caused by non-working mode self-excitation in an S-band long pulse relativistic klystron amplifier
Authors: Chen Zhao-Fu  , Huang Hua  , Chang An-Bi  , Xu Zhou  , He Hu  , Lei Lu-Rong  , Hu Jin-Guang  , Yuan Huan  , Liu Zhen-Bang  ,   Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

We have investigated the pulse shortening problem of relativistic klystron amplifier. It is shown that non-working mode self-excitation is an important cause of pulse shortening. Theoretical and numerical analyses show the mechanism of non-working mode self-excitation caused by the coupling between cavities. By the use of radio frequency absorbers, the problem of non-working mode self-excitation can be solved. In the experiment, the RF output power is 920 MW, the output power pulse width of the device can be increased from 77 ns to 137 ns.
Research on the beam-wave interaction theory of folded waveguide traveling wave tubes based on three-port network model
Authors: Yan Wei-Zhong  , Hu Yu-Lu  , Li Jian-Qing  , Yang Zhong-Hai  , Tian Yun-Xian  , Li Bin  ,   National Key Laboratory of Science and Technology on Vacuum Electronics, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

A general equivalent model for slow-wave structure is established in this paper, if the unit cell of the periodic slow-wave structures is represented by a three-port network and the parameters of the equivalent model are determined by a high frequency structural simulator. In this method, there is no need to find a complicated equivalent circuit, and the fields in the tunnels can be calculated by the high frequency software directly. Therefore, the three-port network model is simpler than the analytic method and no more complex than the common equivalent circuit model. A one-dimensional nonlinear beam-wave interaction theory suitable for the folded-waveguide traveling wave tubes (TWTs) is accomplished based on the three-port network model. And a one-dimensional nonlinear beam-wave interaction code, which complies with the MATLAB language, is used to simulate a folded-waveguide TWT. The difference between the results obtained from the code and the experimental data is less than 10%. This theory can be used in the design of novel folded-waveguide TWTs and research on nonlinear simulations.
X-band high power microwave combination technology based on the off-axis relativistic klystron amplifiers
Authors: Zhan Chang-He  , Li Tian-Ming  , Meng Lin  , Li Zheng-Hong  , Wu Yang  , Shao Jian-Bo  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China;,   School of Science, Southwest University of Science and Technology, Mianyang 621010, China
Published: December 2020

In this paper, in order to overcome the self-excited oscillation in the high-gain relativistic klystron amplifier, an X-band high-gain relativistic klystron amplifier (RKA) is designed driven by the relativistic beam with its current at a kA-level. The corresponding diode impedance is 800 Ω. Its output power reaches 284 MW at the frequency of 9.47GHz, and the gain and efficiency are 50.6 dB and of 37.4% respectively when the beam voltage is of 800 kV. And for the obtained GW-level RF power in low-impedance pulsed power sources, the power microwave combination technology of off-axis eight-tube high-gain RKA is used. In the three-dimensional model, the microwave output of this kind of RKA is almost constant when the device is at off-axis 54 mm. Simulation is based on the 4.5 T superconducting magnet which is 4.5 m long in the laboratory, and the eight-tube high-gain RKA is simulated using a magnet with the microwave output of 284 MW. Then an eight to one power combiner is designed using HFSS software, and the combiner with eight-tube high-gain RKAs is simulated by a three-dimensional model. Its output power is 1.84 GW, with a gain of 50.7 dB and efficiency of 28.8% respectively.
Research on attaining methods of rainfall "truth" by assessment of radar measurement of rainfall
Authors: Yin Zhong-Hai  , Zhang Pei-Yuan  , Cheng Ming-Hu  ,   School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Meteorological Observatory of Hunan Province, Changsha 410007, China;,   Chinese Academy of Meteorological Sciences, Beijing 100081, China;,   Atmospheric Observation Technical Center of China Meteorological Administration, Beijing 100081, China
Published: December 2020

Using the precipitation data given by high-density regional automated weather stations during main flood season in Hunan Province, in 2013, Cressman algorithm is introduced to calculate the regional precipitation value in 0.01°×0.01° resolution and is compared with the methods of a reciprocal of distance square, distance exponent, and distance square exponent. It is shown that the precipitation construction of Cressman algorithm is finer and closer to the features of gage data than other methods. Precipitation accumulation amount given by Cressman algorithm is in agreement with those obtained using methods of reciprocal of distance square and range exponent as well. Cross-validation tests show that the number with the absolute error less than 0.5 mm accounts for 98.71% of total gage number. The standard deviation of error is 0.24 mm, which is the least of all methods. As to 0.01°×0.01° resolution, the regional precipitation calculated by Cressman algorithm is adaptable to validate the radar estimation rainfall.
Characteristics of winter-to-winter recurrence of atmospheric temperature in the northern area of East Asia
Authors: Wang Xiao-Juan  , Qiao Shao-Bo  , Shen Bai-Zhu  , Feng Guo-Lin  ,   Department of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500, China;,   Institute of Meteorological Science of Jilin Province, Changchun 130061, China
Published: December 2020

Seasonal evolution of atmospheric temperature with winter-summer-the following winter (winter-to-winter) characteristics in the northern area of East Asia (40–50°N, 100–130°E) from 1953 to 2012 has been investigated in this paper. Results indicate that: from 2008 on, the atmospheric temperature in this area had a typical characteristic of cold winter-warm summer-the following cold winter for three consecutive years from the lower layer to the upper layer (1000–400 hPa), and the similar situation also appeared in the period from 1950s to 1960s; however, the opposite variation characteristics of warm winter-cool summer-the following warm winter happened in 1990s. This typical seasonal evolution of atmospheric temperature was defined as a new variation mechanism: winter-to-winter recurrence (WWR). The recent 60 years may be divided into four different types according to the variation of the years from 1953 to 2012: negative (positive) winter-to-winter recurrence (negative/positive WWR) and negative (positive) non winter-to-winter recurrence (negative/positive non-WWR). In the 23 WWR years the probability of occurrence was close to 40%. This WWR characteristic still exists and is independent of the variation of the El Niño southern oscillation index. The synthetic anomalies analysis of geopotential height, vertical speed, and the winter vector at 850 hPa indicates that as for the WWR pattern, the dynamic process of inner atmosphere also has WWR characteristics corresponding to the atmospheric temperature from the lower layer (1000 hPa) to the upper layer (500 hPa) while the non-WWR pattern does not have the similar characters. This study will provide a new idea to further investigate the frequent occurrence of the winter low temperature events on the background of global warming.
Research on the optical variability of oscillating disk
Authors: Ou Jian-Wen  , Zheng Yong-Gang  , Zhang Xiong  ,   School of Physics and Electronic Information Technology, Yunnan Normal University, Kunming 650500, China
Published: December 2020

Theoretical study shows that stochastic oscillations of an accretion disk should induce the variability of active objects, however, observations indicate that it contains both chaotic factor and random noise. We develop a “chaotic + stochastic” oscillating accretion disk model for the variability. In this model, the chaotic factor is introduced into the oscillating accretion disk, and the chaotic attractor is reproduced through analyzing the phase pattern of disturbance. Results show that: when the random factor dominates the variability, the light curve exhibits a strong randomness; when the random factor is equal to the chaotic factor, the light curve shows a “heartbeat” which is similar to an electrocardiogram; when the chaotic factor dominates the variability, the light curve shows a certain orderliness. The correlated dimension of the simulated light curve is consistent with the correlated dimension of observational data. This suggests that there is an intrinsic relationship between the simulated light curve and observational data.
Differential quotient rules of operator in composite function and its applications in quantum physics
Authors: Xu Shi-Min  , Xu Xing-Lei  , Li Hong-Qi  , Wang Ji-Suo  ,   Department of Physics and Electronic Engineering, Heze University, Heze 274015, China;,   Key Laboratory of Quantum Communication and Calculation, Heze University, Heze 274015, China;,   College of Physics and Engineering Qufu Normal University, Qufu 273165, China
Published: December 2020

Differential quotient rule of composite function operator and its applications in quantum physics, quantum statistics, operator ordering theory, matrix theory and control theory are given. The integration problem of Wigner operator and Weyl corresponding rules are studied. Two kinds of typical operator identity formulas are proved. The differential form of Wigner operator in ordered product of operators and new differential form of important functions are obtained. Finally, a Wigner operator with parameter for unifying regular order, Weyl sequencing and abnormal order is introduced.
Microblog propagation network model based on mean-field theory
Authors: Wu Teng-Fei  , Zhou Chang-Le  , Wang Xiao-Hua  , Huang Xiao-Xi  , Chen Zhi-Qun  , Wang Rong-Bo  ,   Institute of Cognitive and Intelligent Computing, School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou 310018, China;,   Fujian Key Laboratory of the Brain-like Intelligent Systems, Cognitive Science Department, Xiamen University, Xiamen 361005, China
Published: December 2020

Microblog is a social medium platform allowing users to share real-time information through the user relationship networks which are established by the mechanism of “following”. Message is spread through the user relationship networks by users' behavior of “retweeting”. The research on the spread mechanism of microblog message is very important for public sentiment analysis and rumor propagation control. In this paper, we intend to explore the process of microblog propagation through structural analysis of microblog propagation network. First, we adopt the data of Sina Microblog to establish microblog propagation network, then analyze the formation mechanism of this network, finally, derive the degree distribution model of microblog propagation network by mean-field theory. Experimental results show that the degree distribution of microblog propagation network is a time-dependent model, and it is a power-law distribution at specific time.
Wien-bridge chaotic oscillator based on fisrt-order generalized memristor
Authors: Yu Qing  , Bao Bo-Cheng  , Hu Feng-Wei  , Xu Quan  , Chen Mo  , Wang Jiang  ,   School of Information Science and Engineering, Changzhou University, Changzhou 213164, China
Published: December 2020

Through introducing a generalized memristor and an LC absorbing network into Wien-bridge oscillator, a kind of memristive Wien-bridge chaotic oscillator is proposed. The dynamical model of the memristive Wien-bridge chaotic oscillator is established, based on which the equilibrium points and their stabilities are studied and the dynamical behaviors are further analyzed when the circuit element parameters are varied. The research findings indicate that the memristive Wien-bridge chaotic oscillator has three determinative equilibrium points and their stabilities depend on the circuit element parameters, and that there exist complex nonlinear phenomena including periodic oscillations, chaotic oscillations and fast-slow effects when the parameters are changed. The experimental circuit is simple and easy to realize. The experimental waveforms and numerical simulations are consistent with each other, which well verify the theoretical analyses.
A novel four-dimensional multi-wing hyper-chaotic attractor and its application in image encryption
Authors: Peng Zai-Ping  , Wang Chun-Hua  , Lin Yuan  , Luo Xiao-Wen  ,   College of Computer Science and Electronic Engineering, Hunan University, Changsha 410082, China
Published: December 2020

In this paper, a novel four-dimensional chaotic system for generating multi-wing chaotic attractors is proposed, and chaotic and hyper-chaotic attractors are generated in different parameters. Besides, basic dynamical properties of the chaotic system, such as equilibrium point Poincaré mapping, dissipativity, power spectrum, Lyapunov exponent spectrum, bifurcation diagram are studied numerically and theoretically. An analog oscillator circuit is designed for implementing the four-wing hyper-chaotic attractors, and the hardware circuit experimental results are shown to be in good agreement with the numerical simulation results. Finally, the four-wing hyper-chaotic system is used for hybrid image encryption of physical chaos encryption and advanced encryption standard encryption algorithm. Because physical chaos is adopted in this system, there does not exist a definitive relationship between plaintexts and ciphertexts. And the statistical characteristics of ciphertexts should be better than those of any other encryption system.
Doppler power spectrum density and multi-antenna system performance in three-dimensional environment
Authors: Zhou Jie  , Wang Ya-Lin  , Hisakazu Kikuchi  ,   College of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department Of Electronic and Electrical Engineering, Niigata University, Niigata 950-2181, Japan
Published: December 2020

In this paper, we develop a series of exponential probability density functions for modeling different distributions of elevation angle (EA) of arrival signals in different tree-dimensional (3D) coverage area scattering environments, and implement the modeling of channel characteristics. First, by assuming that the distribution of azimuth angle is uniform, in this paper the closed-form expressions of power spectrum density (PSD) for both symmetric and asymmetric situations of EA are derived. It can be observed from the analysis results that the PSD is closely correlated to EA function and the boundary angles βmin and βmax of the arrival signals and also to the Doppler shift. Then the spatial fading correlation (SFC) of MIMO multi-antenna signals in 3D environment is derived and simulated. The results show that the SFC between MIMO multi-antenna elements is closely related to βmin and βmax, and the parameter of EA function has little effect on SFC. The exponential EA probability function which is introduced in this paper can be applied to channel parameter estimation of multiple wireless communication environments. Compared with traditional models, this model presents the parameter estimation that satisfies theoretical and empirical values, and this model also expands the modeling of statistical channel in 3D environment.
The shape regulation of probability density function for stochastic systems
Authors: Yang Heng-Zhan  , Qian Fu-Cai  , Gao Yun  , Xie Guo  ,   School of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China;,   The National-Local Joint Engineering Laboratory for New Network and Detection Control, Xi'an Technological University, Xi'an 710021, China
Published: December 2020

For nonlinear stochastic systems which are excited by Gaussian white noise, an innovational regulation method is proposed to control the shape of the probability density function of state response to track a desired shape. Firstly, a polynomial feedback scheme is established, and the nonlinear part is replaced by polynomials expansion. Then the recursive equations of the moments which are related to control gain are derived under Fokker-Planck-Kolmogorov theory framework. Meanwhile, regarding the tracking requirement, an optimization problem about the moment approximation is constructed, and the gain of regulation function is obtained by solving this optimization problem using the gradient method. Furthermore, the probability density function of state response is reconstructed from the relationship of the Fourier transform pairs between the characteristic function and probability density function. Finally, two examples are given to demonstrate the effectiveness of the method developed in this paper.
Analysis of scale-free characteristic on sharp variation point of traffic flow
Authors: Zhang Yong  , Li Shi-Gao  ,   Department of Mathematics and Computer, Wuhan Polytechnic University, Wuhan 430024, China
Published: December 2020

Traffic flow time series at different time scales have different fluctuation characteristics. In order to analyze the discontinuity characteristics of traffic flow, a traffic volume time series is adopted as an empiric study objective. The multi-scale sharp variation points of the sequence are obtained by using wavelet transform. The scales are divided based on the corresponding number of the zero-crossing points of wavelet transform, and the hierarchy of the scales is analyzed. The results of calculation indicate that the number of sharp variation points of the traffic flow on a mutation scale is self-similar in a certain scale if the number of the sharp variation points is used as a measure. So, sharp variations of the traffic flow in different scales are scale-free.
Cross-phase modulation typed frequency resolved optical gating measurement for ultra-short pulses using a single mode fiber
Authors: Ma Xiao-Lu  , Li Pei-Li  , Guo Hai-Li  , Zhang Yi  , Zhu Tian-Yang  , Cao Feng-Jiao  ,   College of Optoelectronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

A new scheme of measuring ultra-short optical pulses, based on the photo-elastic effect and cross-phase modulation (XPM) effect in a single-mode fiber, is proposed. In this novel scheme, a variable delay is generated in the former part of the single-mode fiber, and the nonlinear effect is produced in the latter part as a nonlinear medium. The structure including only one single-mode fiber is very simple and low-cost, and needs no complex optical circuit calibration. In addition, XPM effect in the fiber can be realized easily without phase matching. Measured pulses can be retrieved by using principal component generalized projects algorithm based on matrix, and the influences of fiber length and the pulse width on amplitude and phase are studied by numerically simulating the scheme proposed. The results show that the ultra-short optical pulses can be measured when fiber length is equal to 2 km, and the accuracy of measurement is improved by increasing the fiber length. The proposed scheme can realize the measurement of optical ultra-short pulse whose pulse width is above 80 fs.
Refractive index sensing characteristic of a hybrid-Fabry-Pérot interferometer based on an in-fiber ellipsoidal cavity
Authors: Wang Ting-Ting  , Ge Yi-Xian  , Chang Jian-Hua  , Ke Wei  , Wang Ming  ,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Provincial Key Lab of Opto-Electronic Technology, Nanjing Normal University, Nanjing 210023, China
Published: December 2020

A hybrid-Fabry-Perot (F-P) interferometer based on an in-fiber ellipsoidal cavity is presented, and the refractive index sensing properties are studied. The ellipsoidal air-microcavity is formed by splicing together a single-mode fiber and a photonic crystal fiber with special arc-discharge technique. The cavity loss is analyzed by using a Gaussian beam model and the ABCD law, and the physical model of electromagnetic transmission is established. According to the cavity length ratio, there are two kinds of the influences of environment refractive index on interference fringe: contrast modulation and wavelength modulation. A fiber refractive index sensor with an enclosed air cavity based on wavelength demodulation is proposed in this paper. The result of simulation shows that the sensors has no turning point in a range of 1-1.6. A wavelength interrogation technique is used to demodulate refractive-index with high sensitivity (～ 37.088 nm·RIU-1) and high resolution (～ 2.69× 10-5) and with low temperature crosstalk. Experimental results are in good agreement with the theoretical ones. The F-P fiber sensor also holds advantages such as compactness, low cost, easy fabrication, high contrast, high resolution, no turning point, and low temperature crosstalk.
First-principles study of electronic structure and optical properties of TiO2 nanotubes
Authors: Xie Zhi  , Cheng Wen-Dan  ,   College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China;,   Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
Published: December 2020

Using first-principles calculations based on the density functional theory, we systematically study the geometry structure, electronic structure and optical properties of the small size (n, 0)-type TiO2 nanotubes (D2 unit decreases with the diameter increasing, and the nanotubes become more stable. At a diameter of about 14 Å, a configuration change occurs. Band structure analysis shows that electronic states of TiO2 nanotubes are localized, and the conductivity is better for nanotubes with small diameters (D2 nanotubes shift from direct band gap to indirect band gap. And the band gap increases with diameter increasing, because π orbital overlap effect is greater than the quantum confinement effect. Owing to the competition between the two effects, the peaks of the dielectric function ε2(ω) will become redshifted or blueshifted. When its diameter is larger than 9 Å ((8, 0) tube), the optical absorption of TiO2 nanotubes will be significantly enhanced.
Generations of energetic deuterons and neutrons from the Coulomb explosion of deuterated ethane clusters
Authors: Dai Li-Jiao  , Li Hong-Yu  ,   College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China
Published: December 2020

The explosion dynamics of deuterated ethane clusters driven by an intense laser pulse is simulated numerically by employing a simplified Coulomb explosion model. The dependences of deuteron kinetic energy and neutron yield on cluster size are investigated respectively in the paper. It is found that the deuteron energy and neutron yield produced from 5.0 nm deuterated ethane clusters are 20.96 keV and 6.31×105 respectively, which are higher than those from 5.0 nm deuterated methane clusters. So it can be inferred that deuterated ethane clusters are superior to deuterated methane clusters as the target for the efficient laser-induced nuclear fusion reaction to achieve a higher neutron yield, which is in accordance with the reported experimental conclusion.
Analysis and improvement of reconstruction phase error in the image plane digital holography
Authors: Shi Bing-Chuan  , Zhu Zhu-Qing  , Wang Xiao-Lei  , Xi Si-Xing  , Gong Li-Ping  ,   Key Laboratory of Optoelectronic Information Science and Technology, Ministry of Education, Institute of Modern Optics, Nankai University, Tianjin 300071, China;,   Jiangsu Provincial Key Laboratory of Optoelectronic Technology, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210046, China
Published: December 2020

The image plane digital holography is commonly used in digital holographic measurement and imaging. The methods of the discrete Fourier transform and the frequency filtering are usually used for reconstructing the object wave in image plane digital holography, and the influence of these algorithms on phase reconstruction is discussed in this paper. Firstly, the influence of the frequency spectrum leakage on phase reconstruction error is analyzed. The results show that the error of the phase reconstruction is very small when the sampling periodicity is an integer, so high accuracy of phase reconstruction can be achieved in this case. But when the sampling periodicity is not an integer, the phase reconstruction error is increased obviously. In order to reduce the phase error caused by the frequency spectrum leakage, the Hanning window is used in the pretreatment of the digital hologram. The result shows that the Hanning window can improve the accuracy of the reconstruction phase effectively.
Detections and analyses of aerosol optical properties under different weather conditions using multi-wavelength Mie lidar
Authors: Di Hui-Ge  , Hou Xiao-Long  , Zhao Hu  , Yan Lei-Jie  , Wei Xin  , Zhao Huan  , Hua Deng-Xin  ,   School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
Published: December 2020

A multi-wavelength Mie-scattering lidar is designed and established for detecting the aerosol profiles under different weather conditions. And inversion algorithm about multi-wavelength lidar signal is studied. The atmosphere observations are carried out in Xi'an city in the winter of 2013 by using the multi - wavelength lidar. The mixed-layer depth, aerosol particle size characteristics, and atmosphere extinction are studied and analyzed on haze, cloudy and sunny days. The mixed layer depth is lower on haze day and is just about 0.4 km, while it can reach 0.5-0.8 km on sunny day. The aerosol particle characteristics are discussed under different weather conditions by using two Ångström exponents, one for the short - wavelength range (355 nm/532 nm) and other for long-wavelength range (532 nm/1064 nm). The long-wavelength Ångström exponent is less than the short-wavelength Ångström exponent on haze day, and it is contrary on sunny day. The results show that there are more coase particles on pollution day. The Ångström exponents significantly decrease, and even become negative in the clouds, showing that cloud particles are relatively large.
Optical control of the vibrational excitation of the polyatomic ions via strong field multi-photon ionization
Authors: Liu Yu-Zhu  , Gerber Thomas  , Knopp Gregor  ,   College of Physics and Opto-electronics Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Paul Scherrer Institute, 5232 Villigen, Switzerland
Published: December 2020

The dynamics of multi-photon ionization of CH3I under strong field has been studied experimentally by femtosecond photoelectron imaging. Ultrafast optical control of the vibrational excitation in a polyatomic ion by strong field multi-photon ionization is experimentally realized. The present work enhances the intensity of the ionization beam from 1.6×1013 to 2.5×1013 W/cm2. In the order of this higher field, a new energy component is observed and attributed. From the photoelectron imaging, photoelectron kinetic energy distributions and the photoelectron angular distributions are obtained. The discussions of the previous letter are mostly based on the photoelectron kinetic energy information, and the present study emphasizes on the trend of the photoelectron angular anisotropy. More detailed dynamics on vibrational optical control is further explored.
Molecular dynamics study of epitaxial compressive strain influence on the radiation resistance of BaTiO3 ferroelectrics
Authors: Wang Yu-Zhen  , Ma Ying  , Zhou Yi-Chun  ,   Faculty of Material Science and Engineering, Xiangtan University, Xiangtan 411105, China;,   Key Laboratory of Low Dimensional Materials and Application Technology, Ministry of Education, Xiangtan 411105, China
Published: December 2020

Radiation displacement effect of BaTiO3 ferroelectric under epitaxial compressive strain is studied by using molecular dynamics simulations which is based on shell model. The numbers of defects, distributions and changes of polarization in the system are calculated before and after radiation under epitaxial compressive strains of 0, 0.4%, 0.8%, 1.2%, 1.6%, 2.0% respectively by using O atom of 1 keV and [001] direction as a primary konck-on atom (PKA). The damaged areas, the displacement distances of the defect, and migration distances of PKA under reverse applied electric field, obtained in the two cases: 2% compressive strain and no strain, are compared. The results show that the polarization of system increases almost linearly with increasing the epitaxial compressive strain, and that both the polarization amplitude and the number of defects decrease after irradiation. The displacement distance of defects under 2% compressive strain, migration distance of PKA under reverse applied electrical field and damaged area are all smaller than under no strain condition, which indicates that epitaxial compressive strain can suppress lattice irradiation damage, and the damage in BaTiO3 can be tuned by introducing epitaxial compressive strain.
New super junction lateral double-diffused MOSFET with electric field modulation by differently doping the buffered layer
Authors: Duan Bao-Xing  , Cao Zhen  , Yuan Song  , Yuan Xiao-Ning  , Yang Yin-Tang  ,   Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In order to break through the limit relationship between the breakdown voltage and specific on-resistance for LDMOS (lateral double-diffused MOSFET), a new super junction LDMOS is proposed with the electric field modulation by differently doping the buffered layer in this paper for the first time based on the buffered SJ-LDMOS. The new electric field introduced by the differently doping buffered layer, owing to the electric field modulation, is brought to the surface electric field of SJ-LDMOS, which alleviates a low lateral breakdown voltage due to the uneven electric field distribution for the LDMOS affected by the vertical electric field. Through the ISE simulation, the results are obtained that the surface electric field is optimized for the proposed SJ-LDMOS when the number of differently doping buffered layers is three. The saturated breakdown voltage for the new SJ-LDMOS is increased by about 50% compared with that for conventional LDMOS, and improved by about 32% compared with that for buffered SJ-LDMOS. The lateral breakdown voltage for unit length is increased to 18.48 V/μm. For the proposed SJ-LDMOS, the specific on-resistance is 25.6 mΩ· cm2 with a breakdown voltage of 382 V, which already breaks the limit relationship of 71.8 mΩ·cm2 with a breakdown voltage of 254 V in the conventional LDMOS.
Origin of nanopore alumina film photoluminescence: three kinds of defect centers
Authors: Li Guo-Dong  , Wang Qian  , Deng Bao-Xia  , Zhang Ya-Jing  ,   School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

Nanopore alumina films (PAF) are fabricated by two-step anodic oxidation of aluminum in oxalic acid. The field emission scanning electron microscope measurement reveals the surface microstructure of PAF, and the defect formation mechanism in PAF is analyzed. The energy dispersive X ray spectroscopy and the Fourier transform infrared spectroscopy results indicate that oxalic ions are incorporated into the PAF in the synthesis process and further heating up to 500 ℃ does not cause oxalic ions to completely decompose. The photoluminescence (PL) spectra of PAF can be divided into three bands by Gaussion fitting method. The measurement results and the defects in PAF show that the PL originate from optical transitions of two kinds of different oxygen-deficient defect centers (F and F+) and oxalic impurities related defect center, PL centered at 402, 433 and 475 nm, respectively. We put forward for the first time that F centers play a leading role. The PL characteristics of the PAF prepared in oxalic acids with different concentrations suggest that three kinds of the luminescent center positions do not change with the increase of the oxalic acid concentration, but their relative intensities change with the increase of the oxalic acid concentration, i.e., F and F+ decrease, oxalic impurities related defects increase, and these will cause the PL peak position to be red-shifted. Finally, we put forward that the oxalic impurities in PAF can be changed by controlling the concentration of oxalic acid. The present experiments and results will be beneficial to the understanding of light-emitting mechanism in PAF, meanwhile, in this paper we propose a new train of thought for PAF preparation application.
Calculation methods of InGaAsSb quaternary alloy band gap
Authors: Liu Chao  , Wei Zhi-Peng  , An Ning  , He Bin-Tai  , Liu Peng-Cheng  , Liu Guo-Jun  ,   National Key Laboratory of High-Power Semiconductor Lasers, Changchun University of Science and Technology, Changchun 130022, China
Published: December 2020

Two popular interpolation formulas of calculating InGaAsSb quaternary alloy band gap energy are discussed, and the calculation results from them are presented and compared. It is found, after the two formulas have been converted into equivalent formulas in the same forms, that in them there is taken into consideration only the influence of bowing parameter in the Γ valley. In this paper, the effect of the spin-orbit splitting on the valence band is considered, and a new method of calculating the InGaAsSb band gap is proposed by introducing the bowing parameter of spin-orbit splitting. The results show that the introduction of the bowing parameter of spin-orbit splitting can improve the accuracy of the calculation results compared with the above two methods. When the fraction of In is less than 0.72, the calculation obtained from our method is most accurate.
Effect of additive zinc on larger diamond crystal growth
Authors: Zhou Zhen-Xiang  , Jia Xiao-Peng  , Li Yong  , Yan Bing-Min  , Wang Fang-Biao  , Fang Chao  , Chen Ning  , Li Ya-Dong  , Ma Hong-An  ,   State Key of Laboratory of Superhard Materials, Jilin University, Changchun 130012, China;,   Tongren University, Tongren 554300, China
Published: December 2020

The large single crystal diamonds are successfully synthesized in a NiMnCo-C system with the zinc additive in a series of the experiments at temperatures of 1270-1400 ℃ and pressures of 6.2-6.4 GPa by the temperature gradient growth. Morphology and structural properties of the synthesized diamond are characterized by optical microscope and scanning electron microscopy. The Raman spectrum is used to investigate the crystallization of synthesized diamond. The results show that the colors of synthetic diamond crystals change from yellow to light yellow and nearly disappears with the increase of the zinc additive. There are a large number of irregular pits in the surface of diamond crystal when the zinc additive is increased up to 3.0 wt.%. the Fourier transform infrared spectroscopy spectra reveal that the nitrogen impurity in the synthetic diamond crystal is predominantly in the form of C center (single substitutional nitrogen atoms), and the nitrogen concentration decreases with the increase of zinc additive. Two possibilities that the zinc powders can be used as the nitrogen getter are given. the Raman spectrum shows that the diamond crystallization can be improved when the zinc additive is less than 3.0 wt.%. We believe that our work is greatly helpful for deeply understanding the natural diamond genesis, enriching the types of diamonds, and expanding the application areas of synthetic diamond.
Syntheses of negative thermal expansion materials Sc2(MO4)3 (M=W, Mo) with a CO2 laser and their Raman spectra
Authors: Liang Yuan  , Xing Huai-Zhong  , Chao Ming-Ju  , Liang Er-Jun  ,   College of Science, Donghua University, Shanghai 201620, China;,   Key Laboratory of Materials Physics of Ministry of Education, School of Physical Science and Engineering, Zhengzhou University, Zhengzhou 450052, China
Published: December 2020

Negative thermal expansion materials Sc2(MO4)3 (M={W}, Mo) are synthesized with a CO2 laser. It is shown that the synthesis of Sc2(WO4)3 or Sc2(MoO4)3 by laser sintering is a rapid process so that a sample can be synthesized within a few or tens of seconds and has the characteristic of rapid solidification. X-ray diffraction and Raman spectrum analyses demonstrate that the synthesized Sc2(MO4)3 (M={W}, Mo) are crystallized into orthorhombic structures and each have a high purity. Temperature dependent Raman spectrum analysis suggests that the synthesized samples do not have phase transitions above room temperature but possibly have weak hygroscopicities. According to the Raman analyses of MoO3, WO3, Sc2(MoO4)3, and Sc2(WO4)3, we draw a diagram describing their phonon energy levels and the photon energy of the laser, and then assess the mechanism of the synthesis by laser sintering. Transferring the laser photon energy to phonon energy is the channel of light-heat converting. The materials react in the molten pool and are solidified rapidly, forming the final products.
An optimization method for ion etching yield modeling combined with factual etching data
Authors: Gao Yang-Fu  , Sun Xiao-Min  , Song Yi-Xu  , Ruan Cong  ,   Tsinghua National Laboratory for Information Science and Technology, State Key Laboratory on Intelligent Technology and Systems, Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China
Published: December 2020

The profile surface simulation is an important method to study the ion etching mechanism. In profile surface simulation, the result of surface evolution is primarily determined by the surface evolution model and the etching yield optimization model as well. However, the currently available surface evolution model is not accurate enough. What's more, most of the data used in etching yield optimization model are based on simulation, while no factual data are used to optimize the parameters of ion etching yield model. In order to solve these problems, the accuracy of current evolution model is improved, the optimal objects of etching yield model are redefined, and the factual etching data are introduced to optimize the etching yield model for the first time. In this paper, parallel method is also adopted to speed up the optimization process, whose optimized parameters are then applied to the etching simulation process that is based on cellular automata. The experimental results show that our proposed approach does improve the accuracy of simulation and greatly shorten the optimization process.
Multi-period analysis of current-mode pulse-train controlled continuous conduction mode converter
Authors: Sha Jin  , Xu Jian-Ping  , Xu Li-Jun  , Zhong Shu  ,   Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

Pulse train (PT) control technique is a discrete, nonlinear control technique for switching converter which benefits from simple design and ultra fast transient response. As an output-power-control-based control technique, a low-frequency oscillation phenomenon occurs in voltage-mode PT controlled switching converter operating in continuous conduction mode. This phenomenon will seriously affect the steady and transient performances of switching converter. In this paper, a current-mode PT (CM-PT) controlled switching converter is studied. The normally working region is studied and the parameter conditions are estimated. Targeting the problem of CM-PT control technique, a modified control technique is proposed.
Two-dimensional model of symmetrical double-gate strained Si single Halo metal-oxide semiconductor field effect transistor with gate stack dielectric
Authors: Xin Yan-Hui  , Liu Hong-Xia  , Wang Shu-Long  , Fan Xiao-Jiao  ,   Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Ministry of Education, School of Microelectronics, Xidian University, Xi'an 710071, China;,   Department of Information and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Published: December 2020

In this paper, a novel symmetrical double-gate strained Si single halo metal-oxide semiconductor field effect transistor with gate stack dielectric is proposed. The two-dimensional Poisson's equation is solved under suitable boundary condition by applying the parabolic potential approximation. This analytical model for the surface potential and the threshold voltage is derived. The strained Si channel is divided into two different doping regions, and the surface potential along the channel, compared with the normal double-gate device (uniform doping channel), exhibits a stepped potential variation, which can increase carrier transport speed. The influence of drain-source voltage on short channel effects (SCEs) is discussed. it is shown that threshold voltage decreases with Ge mole fraction increasing in butter layer, increases with the increase of the high-k layer dielectric permittivity of gate stack, and increases with the increase of doping concentration in the channel near the source, of which the physical mechanisms are analyzed and explained. Results show that the novel device can suppress threshold voltage drift and SCEs, which provides the basic guidance for designing the CMOS-based devices in nanometer scale.