bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-dimensional plasma hydrodynamic of X-ray laser based on self-similarity model
Authors: Meng Li-Min  , Teng Ai-Ping  , Li Ying-Jun  , Cheng Tao  , Zhang Jie  ,   (1)中国科学院物理研究所,北京  100190; (2)中国矿业大学理学院,北京  100083; (3)中国矿业大学理学院,北京  100083；中国科学院物理研究所,北京  100190
Published: December 2020

A simplified two-dimensional plasma hydrodynamic modal of X-ray laser on slab target is proposed on the basis of self-similarity method. The properties of two-dimensional hydrodynamics of X-ray laser plasma are studied using the model. It is shown that after the action of driving laser, the electron temperature and the electron density along the focus line will tend to equibrium with elapse of time. This result has an important meaning in the optimized design of the experiment on the X-ray laser.
Analysis of linear defect modes in two-dimensional photonic lattices by employing Brillouin zone spectroscopy
Authors: Liu Sheng  , Zhang Peng  , Xiao Fa-Jun  , Gan Xue-Tao  , Zhao Jian-Lin  ,   西北工业大学理学院光信息科学与技术研究所，陕西省光信息技术重点实验室，西安  710072
Published: December 2020

The formation of defect modes in optically induced photonic lattices with one_and two_dimensional defects are analyzed by combining the diffraction relationship of uniform lattices and the Brillouin zone spectra. The defect modes associated with different high symmetry points in Brillouin zone are obtained, including the positive and negative defect modes bifurcating from the X1 point, which is “embedded” in the photonic bandgap. It is revealed that, for two_dimensional defects, the positive （negative） defect modes exist only in the regions corresponding to normal （anomalous） diffraction along both principal axes in k-space, whereas for one_dimensional defects, the positive （negative） defect modes can exist in the regions corresponding to normal （anomalous） diffraction along a single direction. The positive defect mode at X1 point predicates the existence of in-band solitons under self-focusing nonlinearity. The conclusions obtained above could be helpful to understanding the formation of lattice solitons （especially in_band solitons） in photonic lattices.
The theoretical and simulation prediction of bistatic reverberation average strength
Authors: Hui Juan  , Wang Zi-Juan  , Hui Jun-Ying  , He Wen-Xiang  ,   哈尔滨工程大学，哈尔滨  150001
Published: December 2020

In researching long-distance interface bistatic reverberation, the scattering area is taken as an elliptical ring. In researching short-distance bistatic reverberation, the model should be a three-dimensional ellipsoid. The ellipse and ellipsoid models can work without wireless communication, only using GPS clock to make sure the systems work synchronously so as to realize ranging and orienting. It is convenient for the integration of bistatic sonar system. The two-dimensional and three-dimensional prediction formulas of bistatic pressure reverberation are deduced, the vector-sensor three-dimensional reverberation is simulated and the anti-reverberation performance of vector-sensor directivity composite is discussed.
The mechanism investigation on shock wave controlled by plasma aerodynamic actuation
Authors: Wang Jian  , Li Ying-Hong  , Cheng Bang-Qin  , Su Chang-Bing  , Song Hui-Min  , Wu Yun  ,   空军工程大学工程学院，西安  710038
Published: December 2020

In order to distinguish whether thermal mechanism or ionization mechanism dominates shock wave control process by plasma aerodynamic actuation, the transformation rules of wedge oblique shock wave control by arc discharge plasma were theoretically deduced using thermal choking model and ionic sound wave model respectively. If the thermal mechanism dominates shock wave control process, the shock wave start point will shift upward, its shape will not bend and its angle will decrease. However, if the ionization mechanism dominates shock wave control process, the shock wave start point will maintain at the wedge forward apex, its shape will bend as two subsections and its angle of first subsection will increase. Then the wedge oblique shock wave control by arc discharge plasma was studied in a small-scale short-duration supersonic wind tunnel, and the test results showed that the shock wave start point shifted upward 4 mm, its angle decreased 8.6% and its shape did not bend, which demonstrated that the thermal mechanism dominated the shock wave control process by plasma aerodynamic actuation.
The particle-in-cell simulation and Monte Carlo collision simulation of the interaction between electrons and microwave in electron cyclotron resonance discharge
Authors: Jin Xiao-Lin  , Huang Tao  , Liao Ping  , Yang Zhong-Hai  ,   电子科技大学物理电子学院，成都  610054
Published: December 2020

The theoretical and computational model is presented to study the interaction between electrons and microwave in electron cyclotron resonance discharge. The interaction between charged particles and microwave is described by particle-in-cell method, the collisions and the interaction between charged particles and boundaries of system are described by Monte Carlo collision method. The quasi-three-dimensional simulation code is original. And the spatio-temporal evolvements of electron energy and microwave field in ECR discharge is diagnosed.
Current-voltage relationship for homogeneous dielectric barrier discharge in helium and nitrogen at atmospheric pressure
Authors: Zhang Yan  , Gu Biao  , Wang Wen-Chun  , Peng Xu-Wen  , Wang De-Zhen  ,   (1)大连理工大学三束材料改性国家重点实验室，大连  116024; (2)大连理工大学三束材料改性国家重点实验室，大连  116024；大连理工大学物理与光电工程学院，大连  116024; (3)河南理工大学机械与动力工程学院，焦作  454000
Published: December 2020

The experimental investigation of the current-voltage relationship of homogeneous dielectric barrier discharge （HDBD） was performed in helium and nitrogen at atmospheric pressure, respectively. The experiment results agree with the simulation results. The glow diacharge mode （GDM） and Townsend discharge mode （TDM） can coexist in one multiple current peak （MCP） discharge sequence in atmospheric He MCP discharge. Moreover, the discharge modes of atmospheric HDBD can be discriminated according to the differential conductivity of the current-voltage relationship in the ascent stage of discharge current, in which the current pulse is GDM if the differential conductivity of the current-voltage relationship is negative,and it is TDM if the differential conductivity is positive. Thus we concluded that, the atmospheric N2 HDBD is TDM.
A molecular simulation of diffusion mechanism of n-alkanes in copper(Ⅱ) benzene-1,3,5-tricarboxylate metal-organic framework
Authors: Wang Dong-Yi  , Xue Chun-Yu  , Zhong Chong-Li  ,   北京化工大学化学工程学院，北京  100029
Published: December 2020

Molecular dynamics simulation was performed to study the diffusion mechanism of n-alkanes C1—C4 in copper（Ⅱ） benzene-1,3,5-tricarboxylate（Cu-BTC）. The self-diffusivities of n-alkanes were calculated, and the diffusion paths of different types in the main and second channels were discussed by means of center of mass probabilities and trajectories. The simulation results indicate that the diffusion of various n-alkanes in Cu-BTC follows their preferential paths, which have distinct diffusion resistance, leading to the difference in diffusivity. The information obtained provides a better understanding of the diffusion of n-alkanes in metal-organic frameworks（MOFs）, as well as to guide the practical applications and future design of new MOFs.
Molecular dynamics simulation of the rotational viscosity and its odd-even effect of nematic liquid crystals nCB(4-n-alkyl-4′-cyanobiphenyls, n=5—8)
Authors: Zhang Ran  , He Jun  , Peng Zeng-Hui  , Xuan Li  ,   (1)中国科学院长春光学精密机械与物理研究所，长春  130033; (2)中国科学院长春光学精密机械与物理研究所，长春  130033；中国科学院研究生院，北京  100039
Published: December 2020

Based on a full-atomic force field model, molecular dynamics （MD） studies of nCB serials（4-n-alkyl-4′-cyanobiphenyls, n=5—8）were performed under the isothermal-isobaric NPT ensemble. The second and forth rank order parameters and the orientational time correlation function （TCF） were obtained by analyzing the trajectory of MD simulation. Then the correlation time was obtained from the fitting of TCF by a single exponential approximation and the rotational diffusion coefficient （RDC） was computed. The rotational viscosity coefficients （RVC） of nCB（n=5—8） were calculated by Nemtsov-Zakharov and Fialkowski equations, which are based on the statistical-mechanical approach. The odd-even effect of RVC, RDC and the correlation time were discussed separately. Reasonable agreement between the calculated results and the measured data published in literature is obtained, including identical odd-even effect.
Microscopic studies of structural transition in iron under one-dimensional strain
Authors: Shao Jian-Li  , He An-Min  , Qin Cheng-Sen  , Wang Pei  ,   北京应用物理与计算数学研究所，北京  100088
Published: December 2020

Molecular dynamics simulation employing an embedded-atom-method potential is performed to investigate the body-centered cubic（bcc）-hexagonal close-packed（hcp） structural transition in single crystal iron induced by isothermal compression along ［001］ divection. Above the critical strain of transition, homogeneous nucleation of hcp phase appears and grows into flakes along the （011） face. The elastic constants C31 and C32 harden during the compression in bcc phase, while C33 undergoes a softening prior to the transition；all the elastic constants increase rapidly with compression after the system entering the hcp phase. Increasing temperature can weaken the hardening and softening process of C33, but affect the stress threshold of transition only weakly. Hcp twins are formed at 300 K, leading to the shear of crystal latlice. For the mixed phase, the potential of hcp phase is greater than that of bcc phase, hcp phase shows an over-relaxation of the stress, and the longitudinal partial stress keeps linearly decreasing with hcp mass fraction throughout the transition.
First-principles investigation of the electronic properties of multiferroic BaCoF4
Authors: Sun Yuan  , Ming Xing  , Meng Xing  , Sun Zheng-Hao  , Xiang Peng  , Lan Min  , Chen Gang  ,   (1)长春工业大学基础科学学院，长春  130012; (2)长春工业大学基础科学学院，长春  130012；吉林大学材料科学与工程学院，长春  130012; (3)吉林大学材料科学与工程学院，长春  130012
Published: December 2020

The electronic properties of multiferroic BaCoF4 with ferroelectric antiferromagnetic phase and paraelectric phase are calculated using density functional theory with spin-polarized generalized-gradient approximation and plane wave pseudopotentials. It is found that anti-ferromagneticism probably favors to the ferroelectric stability at low temperature and the ion bond interaction is the main interation in the BaCoF4 system due to the strong electronegativity of F atoms. As to the CoF6 octahedron, there is entirely ionic bond between Co ion and F（2） or F（3） ions （bc plane）, but weak covalent bond between Co ion and F（1） ion and still weaker for F（4） ion. The ferroelectric distortion is only induced by relative displacement of Ba ion and F ion along c axis, and F（4） displacement contributes least to ferroelectric phase transformation . In addition, the energy of s and p orbitals of F（2） or F（3） ion is lower in the ferroelectric phase than in the centor-symmetric phase and the covalence character of F（1） ion, whose contribution to the displacement is the largest, is almost lost, which stabilizes the structure of the ferroelectric system.
Propagation characteristics of the broadband supercontinuum with an attosecond ionization gate
Authors: Li Qian-Guang  , Lan Peng-Fei  , Hong Wei-Yi  , Zhang Qing-Bin  , Lu Pei-Xiang  ,   (1)华中科技大学武汉光电国家实验室，武汉  430074; (2)华中科技大学武汉光电国家实验室，武汉  430074；孝感学院物理与电子信息工程学院，孝感  432000
Published: December 2020

The propagation of high-order harmonics with attosecond ionization gate is simulated with three-dimensional propagation equation. After 0.5 mm propagation distance， the short trajectories in the harmonics， which are generated by two 5 fs laser pulses centered at 800 and 400 nm， are selected and a highly efficient smooth supercontinuum with the bandwidth of about 80 eV is obtained in the plateau， because of the phase matching. Simulation results of different propagation distances show the broadband supercontinuum can last steadily. A highly efficient pure isolated attosecond pulse with the duration of about 135 as can be generated by directly filtering out of the harmonics from 60—90 eV in the supercontinuum， and a single 50 as pulse can be generated， which facilitates the experimental implementation for the isolated attosecond pulse generation.
Dielectric loss of ZnO varistor ceramics by variable temperature spectroscopy
Authors: Cheng Peng-Fei  , Li Sheng-Tao  , Li Jian-Ying  ,   (1)西安工程大学理学院，西安  710048; (2)西安交通大学电力设备电气绝缘国家重点实验室，西安  710049
Published: December 2020

In this paper， the dielectric spectra of ZnO varistor ceramic were measured by Novocontrol wide band dielectric spectrometer in the temperature range of -100 ℃—20 ℃ and frequency range of 10-2—106 Hz. It is found that the activation energy is 0.26 and 0.36 eV， respectively. After careful analysis of the measurement conditions， quantitative calculation results and other phenomena， three relaxations of cathode electron injection， dipole polarization and interface polarization are discarded. Thermally stimulated current（TSC） has three peaks， of which the higher temperature peak comes from thermionic polarization introduced by TSC itself， and other two peaks correspond to the characteristic loss peaks in dielectric spectra. Therefore， it is concluded that the characteristic loss peaks of ZnO ceramics originate from electronic relaxation of intrinsic defects.
Dynamical reversal of rectangular nanodot studied by micromagnetics
Authors: Song San-Yuan  , Guo Guang-Hua  , Zhang Guang-Fu  , Song Wen-Bin  ,   (1)中南大学物理科学与技术学院，长沙  410083; (2)中南大学物理科学与技术学院，长沙  410083；中南大学粉末冶金国家重点实验室，长沙  410083
Published: December 2020

The dynamical reversal of rectangular CoFe nanodot with initial C-state subject to square magnetic field pulse has been studied by using the micromagnetic simulations. It was found that the reversals proceeded through different modes as the pulse amplitude is increased. For the weak magnetic field pulse， the magnetization reversal is realized through the motion of the end domain walls toward the central part of magnet and， subsequently， the formation and motion of a single vortex. As the strength of magnetic field pulse become stronger， the reversal is accomplished through the motion of the end domain walls plus the formation and motion of two vortex structure. For much stronger field pulse the reversal process is the motion of the end domain walls and subsequent formation and annihilation of several vortices. The dependence of reversal time on the field pulse amplitude displays oscillating characteristic due to the transitions of reversal modes with the field strength.
The quantum coherent left handness of Λ-type four level system in Er3+：YAlO3 crystal
Authors: Liu Chun-Xu  , Zhang Ji-Sen  , Liu Jun-Ye  , Jin Guang  ,   (1)中国科学院长春光学精密机械与物理研究所，长春  130033; (2)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室，长春  130033
Published: December 2020

We first calculated the negative refractive index on the solid Er3+：YAlO3 crystal with a Λ-type four-level scheme proposed for atomic vapour by Thommen and Mandel and Kastel using quantum interference and electromagnetically induced transparency （EIT）. It is shown that the frequency band with the negative index is wider （～1 MHz） than that reported previously. Usually，Im［n］ is always positive，corresponding to absorption，and the ratio of refraction to absorption，|Re［n］/Im［n］|，is only of the order of unity. In our case the ratio |Re［n］/Im［n］|=4.6，which indicates that the absorption has been well suppressed by EIT approach. The negative Im［n］ may be related to the stimulated emission of 4I13/2→4I15/2 of rare earth ion Er3+. It indicates that the rare earth ion doped material with abundant energy levels and various electric and magnetic transitions is an outstanding and practical candidate for electromagnetically induced negative refractive index material.
Grain size dependence of the dielectric properties of Ba0.70Sr0.30TiO3 ceramics and its mechanisms
Authors: Mao Chao-Liang  , Dong Xian-Lin  , Wang Gen-Shui  , Yao Chun-Hua  , Cao Fei  , Cao Sheng  , Yang Li-Hui  , Wang Yong-Ling  ,   中国科学院上海硅酸盐研究所，上海  200050
Published: December 2020

By successfully fabricating dense Ba0.70Sr0.30TiO3 ceramics in the size range of 0.1—10 μm，the grain size dependence of the Curie temperature TC，dielectric constant in ferroelectric phase εF and in peak εM were systematically investigated. The results show that TC will not decrease considerably until the grain size becomes small enough. This can be explained by Buesseums internal stress model. As the grain size increases，εF increases first and decreases afterward，which can be interpreted by Shaikhs series-parallel model. The main active factors are internal stress，domain and grain boundary. On the other hand，if the grain size is small，εM increases first and decreases afterward as the grain size increases. If the grain size is bigger，εM increases slightly. This can be explained by the diffuse phase transition theory and series-paralled model. The main active factors are grain boundary，internal stress，for small grain sizes, and domain and grain boundary for bigger grain sizes，respectively.
Calculation and experimental research of the spatio-temporal dynamics of Q-switched rep-rated Yb:YAG disk laser
Authors: Yan Xiong-Wei  , Yu Hai-Wu  , Cao Ding-Xiang  , Li Ming-Zhong  , Zheng Jian-Gang  , Jiang Dong-Bin  , Jiang Xing-Ying  , Duan Wen-Tao  , Wang Ming-Zhe  ,   中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

Based on the energy-level structure of quasi-three-level Yb ion，an amplified spontaneous emission model in pumping process is set up. The stored energy density distribution and the energy that can be extracted in Yb：YAG crystal are calculated. Our calculation，which is based on the laser rate equations and the theory of anglular spectrum propagation，can simulate time-resolved evolution of the spatial intensity distribution and M2 factor of the laser pulses. At the same time，an experiment in laser diode-pumped Q-switched rep-rated Yb：YAG disk laser was performed. This model was proved to be correct by comparing the results of the experiment and calculation，which will be helpful in designing active Q-switched solid laser.
Activation mechanism of negative electron affinity GaN photocathode
Authors: Qiao Jian-Liang  , Tian Si  , Chang Ben-Kang  , Du Xiao-Qing  , Gao Pin  ,   (1)南京理工大学电子工程与光电技术学院，南京  210094; (2)南京理工大学电子工程与光电技术学院，南京  210094；南阳理工学院电子与电气工程系，南阳  473004; (3)重庆大学光电工程学院，重庆  400030
Published: December 2020

The photocurrent curves during either Cs or Cs/O activation of GaN photocathode were tested by using dedicated experimental system for activation and evaluation of negative electron affinity （NEA） photocathode. Aiming at explaining the formation of NEA property of GaN photocathode and according to the rule of photocurrent change during activation period and the surface model of a fully activated photocathode，the activation mechanism for NEA GaN photocathode was studied. The experiment results show that：the obvious NEA property is be induced in GaN photocathode mainly due to the activation by Cs. The increase extent of photocurrent is not large after introducing O during Cs/O activation process for GaN photocathode. The NEA property formation reasons of GaN photocathode after being activated successfully can be well explained using the double dipole layer model ［GaN（Mg）：Cs］：O—Cs.
Search for TeV GRBs using Tibet ASγ data
Authors: Zhou Xun-Xiu  , Hu Hong-Bo  , Huang Qing  ,   (1)西南交通大学理学院，成都  610031; (2)中国科学院高能物理研究所，北京  100049
Published: December 2020

TeV energy emission from gamma ray bursts （GRB） is very important for studying the origin and the radiation mechanism of GRB. Searching for TeV GRBs is carried out by using the Tibet ASγ data. A GRB candidate is a shower cluster appearing in a given small sky window and a given time interval. An equi-zenith-angle method is used to estimate the background. In this analysis，two methods are applied in searching for possible GRBs signals，one considers the coincidence with satellite GRB data and the other doesnt. No significant TeV GRBs is detected in either case. The upper flux limit on top of the atmosphere at the 95% confidence level is estimated to be about 3.32×10-9—1.24×10-7 cm-2·s-1 accordingly.
The new exact solutions of Volterra difference-differential equation and KdV difference-differential equation
Authors: Taogetusang  , Sirendaoerji  ,   (1); (2)内蒙古师范大学数学科学学院,呼和浩特  010022
Published: December 2020

Based on the auxiliary equation method and the trial function method, a method for combining function transformation with auxiliary equation is proposed. And the method is applied to construct new exact solitary wave solutions and triangle function solutions of Volterra and KdV difference-differential equations with the help of symbolic computation system Mathematica. Our method can also be applied to other nonlinear difference-differential equations.
Optimal traffic routing strategy on scale-free complex networks
Authors: Li Tao  , Pei Wen-Jiang  , Wang Shao-Ping  ,   东南大学信息科学与工程学院,南京  210096
Published: December 2020

In this paper, we propose a new routing strategy to improve the transportation performance on scale-free networks, named optimal routing strategy. It can proportionally distribute the traffic load between central nodes and the noncentral nodes. Analytical results indicate that by using the optimal routing strategy, the network capability in processing traffic is proportional to the square of the network size and is independent of each node degree. Simulations show that compared with the classic shortest path routing strategy, the new strategy can enhance the network capability several times with the small-world character and its performance is gradually improved with the increasing of the average degree. Moreover, the comparison with the efficient routing strategy also reveals the prominent performance of the new strategy.
Effects of subharmonic motion on size segregation in vertically vibrated granular materials
Authors: Jiang Ze-Hui  , Jing Ya-Fang  , Zhao Hai-Fa  , Zheng Rui-Hua  ,   哈尔滨工业大学物理系,哈尔滨  150001
Published: December 2020

Experiments have been performed to investigate the effect of subharmonic motion on size segregation in vertically vibrated granular beds. In our experimental systems, symmetric normal convection of granular particles is induced when vibration acceleration is sufficiently large, and subharmonic motion of the particles appears when vibration acceleration is above another larger critical value. Observations reveal that particle convection is the main mechanism leading to the segregation of larger intruder particles imbedded in smaller ones, the convection flux dominates the rising time of the intruder, and a distinct retardation of the segregation time is induced when the bed’s bulk motion undergoes period-doubling and period-quadrupling bifurcations. An analysis of the convection due to the effects of air is given. Then the mechanism leading to such retardation is discussed and simple expression for the segregation time is formulated. The obtained results agree well with experimental values.
Analytical model for probe impedance using reflection and transmission theory in eddy current testing
Authors: Fan Meng-Bao  , Huang Ping-Jie  , Ye Bo  , Hou Di-Bo  , Zhang Guang-Xin  , Zhou Ze-Kui  ,   浙江大学控制科学与工程学系,工业控制技术国家重点实验室,杭州  310027
Published: December 2020

The analytical model of probe impedance due to multilayered conductive structures is established using the reflection and transmission theory of electromagnetic waves in eddy current testing. The electromagnetic field in the region under considecation consists of the excitation field of the coil and the eddy current field. The eddy current field is regarded as the combination of the reflection and transmission of the excitation field. Therefore, the probe impedance is analytically modeled by applying the series-form representation of the excitation field and the reflection and transmission theory of electromagnetic waves, thus resulting in a series-form expression. Finally, the calculated results from the typical integral-form and developed series-form expressions were compared, and experiments were carried out. The good agreement between the calculated and experimental results justifies the presented analytical model. In comparison with the infinite integral of probe impedance, the series-form expansion has advantages of not needing the determination of the integral upper limit, saving time and easy control of the error.
Time evolution of entanglement for the two spin-1/2 particles system
Authors: Lu Peng  , Wang Shun-Jin  ,   四川大学物理科学与技术学院理论物理中心,成都  610064
Published: December 2020

The Heisenberg spin cluster with two particles controlled by a time-dependent magnetic field is investigated. Since the system possesses an SU（2） algebraic structure, the exact analytical solution to time evolution operator can be obtained by using algebraic dynamical method. Based on the analytical solution, the time evolution of wave function of the two-particle system can be obtained, then the entanglement can be calculated easily. The time evolution of the entanglement for different initial states is studied, and the effect of external field on the entanglement is discussed as well.
Linear optical realization of universal unambiguous discrimination of quantum state
Authors: Lin Qing  ,   福建省华侨大学厦门校区信息科学与工程学院,厦门  361021
Published: December 2020

In this letter, we propose an experimental scheme of universal unambiguous discrimination with only linear optical elements and the coincidence measurements. In addition, a modified scheme is presented to increase the success probability with ancillary photons. This scheme is feasible by current experimental technology and may be used in quantum cryptography.
An extended Grassberger-Rosenbluth method and simulation of the screening behavior of linear polymer solutions
Authors: Jiang Jian-Guo  , Zhang Jin-Lu  , Zhou Heng-Wei  , Zhang Li-Li  , Huang Yi-Neng  ,   (1)南京大学物理系固体微结构实验室，南京  210093; (2)南京大学物理系固体微结构实验室，南京  210093；伊犁师范学院物理与电子信息学院 凝聚态物理与材料设计研究所，伊宁  835000; (3)伊犁师范学院物理与电子信息学院 凝聚态物理与材料设计研究所，伊宁  835000
Published: December 2020

We extended the pruned-enriched Rosenbluth method, which was proposed by Grassberger for simulating a single self-avoiding walk （called GR method for the sake of convenience）, to simulate multi-avoiding walks. For simplicity this method is called extended GR （E-GR） method and used to investigate the screening behavior of linear polymer solutions. The simulations show that the screening is a cooperative behavior of monomers on other chains, i.e. it is not only dependent on the concentration of solutions but also on the length of other chains. The simulated screening behavior agrees with the experiments and the prediction of the self-consistent field theory. These results also show the validity and potential applications of E-GR to study other physical properties of linear polymer solutions.
Study on the generalized projective synchronization of improved invariable-Lyapunov-exponent-spectrum chaotic system
Authors: Li Chun-Biao  , Shan Liang  , Wang De-Chun  ,   (1)南京理工大学电子工程与光电技术学院，南京  210094; (2)南京理工大学电子工程与光电技术学院，南京  210094；江苏省食品安全工程技术研究开发中心电源与系统部，南京  210007；江苏经贸职业技术学院工程技术学院，南京  210007; (3)南京理工大学自动化学院，南京  210094
Published: December 2020

The generalized projective synchronization of improved invariable-Lyapunov-exponent-spectrum chaotic system is studied. The appropriate nonlinear feedback controllers are designed by an active control method for synchronization of two chaotic systems with the same or different structures. The effectiveness of scaling factor and global linear amplitude adjuster in the generalized projective synchronization system is analyzed. The driving, control and response subsystems of the synchronization system are analyzed in detail and constructed based on modularization and reusing. Numerical simulation and circuit experiment simulation all show that any scale signal of driving system state variable can be obtained by adjusting the scaling factor. When the global linear amplitude adjuster is changed, the state variables of driving system and response system are modulated synchronously in linearity while the generalized projective synchronization between the two systems is not influenced.
Adaptive controlling chaos in permanent magnet synchronous motor based on the LaSalle theory
Authors: Wei Du-Qu  , Zhang Bo  , Qiu Dong-Yuan  , Luo Xiao-Shu  ,   (1)广西师范大学物理与电子工程学院，桂林  541004; (2)华南理工大学电力学院，广州  510640; (3)华南理工大学电力学院，广州  510640；广西师范大学物理与电子工程学院，桂林  541004
Published: December 2020

Recent investigation has shown that the permanent magnet synchronous motor （PMSM） goes chaos for certain parameter values or under certain working conditions, which threatens the secure and stable operation of the motor. Hence, it is significant to study the method of controlling or suppressing chaos in PMSM. Based on LaSalle invariant theory, an adaptive law of controlling chaos was presented in this paper, which enablcs avoiding the influence of undeterministic equilibrium of the system. Simulation results show that the designed control method is effective and its control property is better than that of others. Our research results may help to maintain the system’s secure operation.
Research on the stability of complexity of chaos-based pseudorandom sequence
Authors: Luo Song-Jiang  , Qiu Shui-Sheng  , Luo Kai-Qing  ,   华南理工大学电子与信息学院，广州  510640
Published: December 2020

Intensive statistical complexity can reflect the random nature of chaos-based pseudorandom sequence. Based on this property, the definition of k-error intensive statistical complexity is presented and two basic properties of it are proved in this paper, which can be used to measure the stability of complexity of chaos-based pseudorandom sequences. Based on chaos-based pseudorandom sequences produced via Logistic, Henon, Cubic, Chebyshev and Tent maps, an example is given to demonstrate how it works. Simulation results indicate that the approach is effective, it can distinguish the stability of diverse chaos-based pseudorandom sequences, and is an effective way for evaluating the stability of chaos-based sequences.
The fundamental problem of inverse scattering method in solving the DNLS equation
Authors: He Jin-Chun  , Chen Zong-Yun  , Huang Nian-Ning  ,   (1)华中科技大学数学与统计学院,武汉  430074; (2)华中科技大学物理学院,武汉  430074; (3)武汉大学物理系,武汉  430072
Published: December 2020

This is a basic work on the inverse scattering transform that constructs the complete orthonormal system of the free Jost solution. In order to establish the system for the DNLS equation, we introduce a new transform for the spectral parameter and a gauge transform. The Marchenko's equation and the Zakharov-Shabat's equation of inverse scattering are derived based on the new spectral parameter.
Spectral line shift of He-like titanium in hot and dense plasmas
Authors: Ran Lin-Song  , Wang Hong-Bin  , Li Xiang-Dong  , Zhang Ji-Yan  , Cheng Xin-Lu  ,   (1)四川大学原子与分子物理研究所,成都  610065; (2)中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900；四川大学原子与分子物理研究所,成都  610065; (4)中国科学院上海光学精密机械研究所,上海  201800
Published: December 2020

By assuming the ion sphere model, the self-consistent field method for the Poisson-Boltzmann equation and the Dirac equation is used to calculate the energy levels of He-like titanium immersed in hot and dense plasmas. Consequently, the spectral shifts of the intercombination line and the resonance line and the shifts of the exchange energy of He-like titanium in hot and dense plasmas are studied. The results show that the two electronic dipole transitions red shift nearly linearly with the increase of plasma electron density. The formula of the linear relationship is found. The results may be useful in developing the new method of dense plasma diagnosis.
Study of the L-subshell X-ray production cross sections of Au by 20—50 MeV O5+ bombardments
Authors: Zhang Bo-Li  , Yang Zhi-Hu  , Du Shu-Bin  , Chang Hong-Wei  , Xue Ying-Li  , Song Zhang-Yong  , Zhu Ke-Xin  , Tian Ye  ,   (1)兰州大学物理科学与技术学院,兰州  730000; (2)中国科学院近代物理研究所，兰州  730000; (3)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100190; (4)中国原子能科学研究院，北京  102413
Published: December 2020

The experiments were performed at HI-13 tandem accelerator at the Chinese Institute of Atomic Energy （CIAE）, in which the L-shell X-ray relative production cross section was measured for solid targets Au bombarded by 20—50 MeV O5+ions. The ratios of Au L-subshell production cross sections σ（Lβ）/σ（Lα），σ（Lγ）/σ（Lα），σ（Ll）/σ（Lα） have been calculated according to the experimental data. The results are compared with the predictions of the ECPSSR theory. Reasonable agreement between theory and experiment was obtained.
Experimental investigation of CPT atomic frequency standard
Authors: Du Run-Chang  , Chen Jie-Hua  , Liu Chao-Yang  , Gu Si-Hong  ,   (1)中国科学院武汉物理与数学研究所，武汉  430071; (2)中国科学院武汉物理与数学研究所，武汉  430071；中国科学院研究生院，北京  100190
Published: December 2020

A small sized and low power consumption physical package of CPT atomic frequency standard developed by us is introduced in the paper. The experiments of locking laser frequency and microwave frequency were carried out and realized with the physical package. By locking laser frequency to atomic absorption spectrum through current negative feedback and locking microwave frequency to electromagnetic induced transparency resonance peak through voltage negative feedback respectively, the locking of the clock frequency of this laboratorial desktop experimental CPT frequency standard is realized. The measurement of the frequency stability of this experimental system demonstrate a performance better than 5×10-11τ-1/2 （1—200 s）.
Density functional study of the interaction of CO with nickel clusters
Authors: Ge Gui-Xian  , Yang Zeng-Qiang  , Cao Hai-Bin  ,   石河子大学师范学院物理系生态物理重点实验室，石河子  832003
Published: December 2020

The adsorption of CO on the Nin cluster surfaces has been systematically investigated by density functional theory. The result indicates that the lowest energy structures of NinCO are generated with CO being adsorbed on Nin clusters, and the lowest energy structures of Nin clusters are not changed by adsorbing CO molecule， The chemisorption of CO on Nin cluster surfaces belongs to non-dissociative adsorption. The increased theoretical CO bond length of 0.1180-0.1214?nm （compared with 0.1138?nm） demonstrates the activation of the CO bond. Natural bond orbital analysis shows that the interaction between Ni atoms and CO molecule is primarily contributed by the hybridized molecular orbital within CO and 3d, 4s, 4p orbital of Ni atoms.
A novel microstrip antenna with dendritic-structured negative permeability metamaterials
Authors: Zhu Zhong-Kui  , Lou Chun-Rong  , Zhao Xiao-Peng  ,   西北工业大学应用物理系，西安  710129
Published: December 2020

Based on electromagnetic characteristic of metallic dendritic cell, negative permeability metamaterial composed of periodic arry of metallic dendritic cells is fabricated. A 2.64GHz microstrip antenna with dendritic structure is proposed. The results show that compared with the conventional microstrip antenna, the performance of the novel microstrip antenna with dendritic-structured negative permeability metamaterial has been improved remarkably. The 3-dB beam width of E-and H-plane can be reduced by 18°and 13°, respectively. The directional property of the antenna is enhanced, the gain is improved by 2.19dB and the efficiency is increased by 65%. It proves that the performance of the microstrip antenna is improved by using negative permeability metamaterial as the substrate.
Coherent and incoherent additions of nonparaxial partially coherent Hermite-Gaussian beams
Authors: Li Chang-Jin  , Lü Bai-Da  ,   (1)内江师范学院物理与电子信息工程学院，内江  641112；四川大学激光物理与化学研究所，成都  610064; (2)四川大学激光物理与化学研究所，成都  610064
Published: December 2020

Analytical expressions for the cross-spectral density and intensity of two-dimensional nonparaxial partially coherent Hermite-Gaussian （H-G） beams in coherent and incoherent additions are derived, and some special cases are analyzed. The intensity of the resulting beam depends not only on the f-parameter, fσ-parameter, off-axis distances, beam numbers and orders of combined beams and propagation distance, but also on the addition scheme. The meaning of the terminology of coherent and incoherent addition of partially coherent beams is interpreted physically and the validity is confirmed by numerical examples.
Light scattering by a spheroid particle with many densely packed inclusions
Authors: Sun Xian-Ming  , Shen Jin  , Wei Pei-Yu  ,   山东理工大学电气与电子工程学院电子信息科学系,淄博  255049
Published: December 2020

Light scattering by a particle containing inclusions is calculated by a combination of ray-tracing and Monte Carlo techniques. The distribution of the inclusions can be sparse or dense. While the individual reflection and refraction events at the outer boundary of a sphere particle are considered by a ray-tracing program, the Monte Carlo routine simulates the internal scattering processes. A dense-medium light-scattering theory based on the introduction of the static structure factor is used to calculate the single scattering characteristics for densely packed inclusions. Numerical results of the single scattering characteristics for a spheroid containing inclusions are discussed.
Analytical model of range-Doppler image of rotating cylinders and cones
Authors: Gong Yan-Jun  , Wu Zhen-Sen  ,   西安电子科技大学理学院，西安  710071
Published: December 2020

We propose a new analytical model of range-Doppler image of cylinders and cones rotating around their axes. This analytical model can manifest the contribution of geometric parameters, roughness of the surface, and attitude as well as pulse duration to range-Doppler image. This analytical model degenerates into the analytical model of Doppler spectra for plane waves. The influence of geometric parameters, roughness of the surface, and attitude as well as pulse duration are analyzed numerically by applying the analytical model. Combining the theory and measurements, the analytical model can be used for parameter identification of cylinders and cones. This analytical solution may contribute to laser Doppler velocimetry and ladar applications.
Studies on Ne-like Ge X-ray laser driven by a 2ω nanosecond laser
Authors: Wang Chen  , Zhang Guo-Ping  , Zheng Wu-Di  , Qiao Xiu-Mei  , Fang Zhi-Heng  , Sun Jin-Ren  , Wang Wei  , Xiong Jun  , Fu Si-Zu  , Gu Yuan  , Wang Shi-Ji  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)上海激光等离子体研究所，上海  201800
Published: December 2020

Generally, it is more suitable for studies on Ne-like X-ray laser by using fundamental frequency laser as driving beam than by frequency doubling. However, many huge laser facilities built for ICF research are usually designed for doubling and trebling of laser frequency, and they are unfit for use as fundamental frequency laser. We simulated the Ne-like Ge X-ray laser making use of JB19 codes, respectively in the case of doubled and trebled frequency diving. The results indicated that the higher power output of Ne-like Ge X-ray laser is also obtained when driven by doubled frequency laser. However the required output of driving laser beam was 3.3 times that in the case of the fundamental. Any way it presents a direction of studying Ne-like X-ray laser with huge laser facilities in the future. A preliminary experimental study has proved this point.
Power spectral density method of defects on optical elements of high-power laser facility and its equivalent algorithm
Authors: Zhou Li-Dan  , Su Jing-Qin  , Li Ping  , Liu Lan-Qin  , Wang Wen-Yi  , Wang Fang  , Mo Lei  , Cheng Wen-Yong  , Zhang Xiao-Min  ,   中国工程物理研究院激光聚变研究中心,绵阳  621900
Published: December 2020

The method of power spectral density（PSD） to describe defects existing on optical elements was proposed for the first time. An equivalent PSD algorithm was composed for treating the presence of plenty of amplitude-modulating micrometer-siged defects using statistical theory, and the method was validated by simulation.
Theory and experiment of refractive index change of long-period fiber grating induced by CO2 laser pulses
Authors: Zhu Tao  , Shi Cui-Hua  , Rao Yun-Jiang  , Chiang Kin-Seng  ,   (1)重庆大学光电工程学院光电技术及系统教育部重点实验室，重庆  400044; (2)重庆大学光电工程学院光电技术及系统教育部重点实验室，重庆  400044；电子科技大学通信与信息工程学院宽带光纤传输及通信网络技术教育部重点实验室，四川  610054; (3)重庆大学光电工程学院光电技术及系统教育部重点实验室，重庆  400044；电子科技大学通信与信息工程学院宽带光纤传输及通信网络技术教育部重点实验室，四川  610054；香港城市大学电子工程系，香港
Published: December 2020

The mechanism of refractive index change of long period fiber gratings （LPFGs） induced by high frequency CO2 laser pulses is investigated in theory and by experiment. It is found that the release of residual stress, rapid solidification, fiber densification and fusion distortion are discovered to be the main mechanisms of formation of this kind of gratings. The above four mechanisms play different roles when different fibers, different scanning methods and the different laser power were used in the process of LPFG fabrication. The average refractive index changes of the core and cladding were measured by using M-Z interferometer formed by LPFG pair in this paper, which provides the experimental basis for fabricating all-fiber devices.
Scalar modulation instability in photonic crystal fiber couplers
Authors: Jia Wei-Guo  , Zhou Yan-Yong  , Han Yong-Ming  , Bao Hong-Mei  , Yang Sheng-Ji  ,   (1)内蒙古大学物理科学与技术学院，呼和浩特  010021; (2)内蒙古自治区产品质量检验所,呼和浩特  010010
Published: December 2020

The nonlinear coupled-mode equations are rewritten by even and odd modes. We study modulation instability of photonic crystal fiber couplers when either even or odd mode is launched alone. The result shows that there are new types of modulation instability in both the normal and the anomalous-dispersion regimes. Modulation instability is related with four phase dispersion and has no relation with three phase dispersion. The gain spectra have been given as function of input power in various dispersion regimes. Quasi-cw can be changed into pulse array under certain conditions, and we can extract super-short pulses from it.
Hollow beam generation from a highly nonlinear photonic crystal fiber with a modified core
Authors: Fang Xiao-Hui  , Hu Ming-Lie  , Liu Bo-Wen  , Li Yan-Feng  , Chai Lu  , Wang Qing-Yue  , Tong Wei-Jun  , Luo Jie  ,   (1)长飞光纤光缆有限公司研发中心，武汉  430073; (2)天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津  300072
Published: December 2020

The mode-controlled nonlinear process in a highly nonlinear photonic crystal fiber is studied experimentally. The central wavelength of frequency-upconverted dispersive wave and its transverse intensity profile are controlled through a selective coupling of the pump field to the higher order modes of the fiber and a polarization-sensitive phase matching process. However, due to their large effective index difference, the two orthogonal modes cant be excited simultaneously. The index difference is lowered by injecting wax into the air holes which effectively modifies the core structure. This modification degenerates the two orthogonal high-order modes. As a result, they are excited simultaneously and form a hollow beam output.
SO-FDTD analysis of EM scattering of magnetized ferrite
Authors: Wang Fei  , Ge De-Biao  , Wei Bing  ,   西安电子科技大学物理系，西安  710071
Published: December 2020

The shift operator （SO） method is extended to the case of magnetized ferrite subject to an external dc magnetic field of arbitrary direction. The FDTD with shift operator （SO-FDTD） formulations are derived based on the relative permeability tensor in magnetized ferrite and Maxwell curl equations of anisotropic media. The electromagnetic （EM） scattering by magnetized ferrite layer, sphere and Von Karman radome with magnetized ferrite coating is computed by the proposed method respectively. The computed results indicate the correctness and feasibility of our method.
Synthesis of pure hexagonal phase aluminium nitride foam
Authors: Lü Hui-Min  , Shi Zhen-Hai  , Chen Guang-De  ,   (1)西安交通大学应用物理系，西安  710049; (2)西安理工大学应用化学系，西安  710048; (3)西安理工大学应用物理系，西安  710048
Published: December 2020

In a stainless steel autoclave of 15 ml capacity, pure hexagonal aluminum nitride （h-AlN） foam has been synthesized by direct reaction of AlCl3 with NaN3 in non-solvent system at 650 ℃ for 3h. The scanning electron microscopy （SEM） shows that the obtained foam material has characteristic sponge-like morphology. The results of X-ray diffraction （XRD） indicate that the AlN foam has a pure hexagonal structure. The absorption spectra at various temperatures indicate that there is a relatively strong absorption peak at about 202 nm. The infrared absorption spectrum shows that the foam has two absorption peaks, centered at 1381 cm-1 and 730 cm-1 respectively. In addition, a possible synthesis mechanism for h-AlN foam is discussed.
Research on the surface scattering properties of optical films by the total integrated scatter
Authors: Hou Hai-Hong  , Sun Xi-Lian  , Tian Guang-Lei  , Wu Shi-Gang  , Ma Xiao-Feng  , Shao Jian-Da  , Fan Zheng-Xiu  ,   (1)常熟理工学院物理系，常熟  215500；中国科学院上海光学精密机械研究所，上海  201800; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

The root mean square （RMS） roughness and surface scattering of Ag films，Y2O3-stabilized ZrO2 films，TiO2 films，and 1064 nm & 532 nm two-wavelength-reflection-reducing films are studied respectively by the total integrated scatter. Considering the preparation condition，growth process，material composition，and optical characteristics of the samples，the above measurement results are explained reasonably.
Electronic theoretical study of the mechanism of the oxide scale formation of Fe-Cr-Al alloy
Authors: Zhang Guo-Ying  , Zhang Hui  , Fang Ge-Liang  , Luo Zhi-Cheng  ,   沈阳师范大学物理科学与技术学院，沈阳  110034
Published: December 2020

The atomic structure models of the surface，the interface of oxide scale and bulk of Fe-Cr-Al alloy were set up by using corresponding computer programming, and the electronic structure parameters （environment-sensitive embedding energy，affinity energy，total energy and total density of states） of alloying elements on the surface，the interface of oxide scale and bulk of Fe-Cr-Al alloy, were calculated by the recursion method. The formation mechanism of the oxide film，the influences of sulfur and rare earth metals on the adhesion of oxide film of Fe-Cr-Al alloy and on the formation course of the oxide film were studied systematically on electronic level. The results show that the driving force of Al atom to segregate on to the surface was larger than that of Cr and Y atom. This leads to the inward diffusion of O atoms and the outward diffusion of Al atoms at the early stage of oxidation，resulting in a surface layer rich in Al and O atoms. The affinity force between oxygen and Al was larger （the affinity energy being lower），oxygen is easy to combine with Al atoms to form Al2O3 oxide scale. Yttrium is segregated to the surface，which inhibits the diffusion of Al to the surface of Fe-Cr-Al alloy. The lateral growth of oxide film is effectively controlled，the occurrence of the convoluted morphology of the scale is avoided，the adhesion of the oxide film to the Fe-Cr-Al matrix is increased by the addition of Y. The diffusion of impurity S to the interface of Fe-Cr-Al matrix and Al2O3 oxide scale increases the total energy of the interface，decreases the total density of states，which reduces the stability of the interface，weakens the cohesion of Fe-Cr-Al matrix and Al2O3 oxide scale.
The investigation of roughing effect sensitive to size in graphene quantum dot device
Authors: Li Gui-Qin  , Cai Jun  ,   清华大学物理系，北京  100084
Published: December 2020

The transport property of graphene quantum dot devices of different length is investigated by first-principles calculation. The changes of transport property caused by roughing effect are sensitive to size of graphene. The results demonstrate that whether the electrode is connected with zigzag edge or armchair edge of graphene，both the transmission coefficient and current always change. But the changes have reversed effect for the two different connections when the length is increased.