bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of zigzag graphene nanoribbons by patterning vacancies
Authors: Zhang Yu  , Liu Lian-Qing  , Jiao Nian-Dong  , Xi Ning  , Wang Yue-Chao  , Dong Zai-Li  ,   State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China;,   Graduate School of Chinese Academy of Sciences, Beijing 100049, China;,   Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan, 48824, USA
Published: December 2020

The transport properties of zigzag graphene nanoribbons (ZGNRs) with different patterns of vacancies are investigated by using the density functional theory and nonequilibrium Green's function (NEGF) formalism. It is found that the transport properties vary with lattice type vacancy. For two vacancies, A-B type vacancies have the most significant influence on the conductance of ZGNRs, while A-A type vacancies have the most slightly influence on the conductance. More importantly, the pattern of vacancies has enormous influence on electron transport around the Femi energy. As hexagon carbons are removed, the ZGNRs will be modified, changing from metallic to semiconducting. This lays the theoretical foundation for tuning the electron properties of ZGNRs by patterning vacancies.
Numerical study of spectrum-control in dual-wavelength LED with doped quantum well barriers of different doping concentration
Authors: Liu Xiao-Ping  , Fan Guang-Han  , Zhang Yun-Yan  , Zheng Shu-Wen  , Gong Chang-Chun  , Wang Yong-Li  , Zhang Tao  ,   Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

Dual-wavelength LEDs with doped quantum well barriers of different doping concentrations are numerically investigated by using the APSYS simulation software. The carrier concentrations, radiative recombination rates, energy band diagrams and spectra are investigated at different doping types and different doping concentrations. The results show that through adjusting the doping concentration of the quantum well barrier a suitable spectrum can be obtained, which will satisfy the need of application. And the effect of spectrum-control in dual-wavelength LED is due to the blocking effect of electrons and holes by doped quantum well barriers.
Radiometric calibration accuracy of airborne synthetic aperture radar in ocean surface wind field sounding
Authors: Zhao Xian-Bin  , Kong Yi  , Yan Wei  , Ai Wei-Hua  , Liu Wen-Jun  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Sounding accuracy is difficult to study systematically and effectively because of complex airborne synthetic aperture radar system. In this paper, according to the role of radiometric calibration accuracy in ocean surface wind field sounding process of airborne synthetic aperture radar, a method is proposed to investigate the system sounding accuracy by radiometric calibration accuracy. The parameter relationship of CMOD4 geophysical model function is simulated. The radiometric calibration accuracy of airborne synthetic aperture radar ocean surface wind field sounding at different incidence angles and in wind directions is ascertained. The results show that the radiometric calibration accuracy decreases with incidence angle increasing and changes periodically with wind direction changing. The law is accordance with the change of backscattering cross-section, cased by wind speed in CMOD4 geophysical model function. According to this law, we find that the accuracy of ocean surface wind field retrieval can be improved by using active calibration scale, designing carrier aircraft crosswind flight and selecting the large incidence angle sounding imagery as retrieval area.
Tuning Fano resonances in a planar metamaterial
Authors: Liu Ran  , Shi Jin-Hui  , Plum Eric  , Fedotov Vassili  , Zheludev Nikolay  ,   College of Science, Harbin Engineering University, Harbin 150001, China;,   Optoelectronics Research Center, University of Southampton, Southampton SO17 1BJ, UK;,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

We demonstrate the tuning of Fano resonances in a symmetric planar metamaterial both experimentally and theoretically, on the basis of a unit cell consisting of two identical split ring resonators. The electromagnetic responses of the planar metamaterial to incident TE and TM waves are measured. By controlling the excitation of the Fano-type trapped-mode resonance via the angle of incidence, the resonance can be switched on/off and the resonance is red-shifted by up to 21%. Based on the finite element method, the field distributions are presented and a very sharp normal phase dispersion renders the response of the structure a metamaterial analog of classical electromagnetically-induced transparency (EIT). The simulated results are in good agreement with the measured ones. The switching feature of the trapped mode resonance in symmetric metamaterial can provide an easy approach to tuning the performance of metamaterial.
Measurement of implosion trajectory for hohlraum-radiative-driven
Authors: Dong Jian-Jun  ,  Cao Zhu-Rong  , Yang Zheng-Hua  , Cheng Bo-Lun  , Huang Tian-Xuan  , Den Bo  , Liu Sheng-Ye  , Jiang Shao-En  , Ding Yong-Kun  , Yi Sheng-Zheng  , Mu Bao-Zhong  ,   Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 21900, China;,   Department of Physics, Tong-Ji University, Shanghai 200092, China
Published: December 2020

The measurement of implosion velocity is the core problem of inertial confinement fusion and it is also a key quantity of estimation of fusion ignition. A clear implosion trajectory X-ray image of hohlraum-radiative-driven CH-capsule is obtained in Sheng-GuangII laser facility with 1600 J laser energy, triple frequency and 1 ns pulse width. KB-microscope coupled with X-ray streak camera whose temporal resolution is about 10 ps is used for diagnosis. The maximal velocity of implosion is about 160 km/s which can be extracted from the experimental trajectory data. The experimental data are compared with Multi1D simulation results of velocity and both are in good agreement with each other.
A new method for projective synchronization of different fractional order chaotic systems
Authors: Huang Li-Lian  , Ma Nan  ,   College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Based on the Lyapunov theory as the breakthrough point, and based on the fractional order system stability theory and properties of fractional nonlinear system, a kind of fractional-order chaotic system is proposed to determine whether the new theorem is stable, and the theory is used for fractional order control and synchronization of chaotic systems, and gives a mathematical proof process to strictly ensure the correctness of the method and general applicability. Then the proposed stability theorem is used to achieve the projective synchronization of fractional Lorenz chaotic system with fractional order chaotic Liu system, as well as the projective synchronization of four-dimensional hyperchaos of fractional order systems of different structures. In the stability theorem solving the fractional balance point and the Lyapunov index are avoided, therefore a control law can be easily selected, and the obtained controller has the advantages of simple structure and wide range of application. Finally, the expected numerical simulation results are achieved, which further proves the correctness and universal applicability of the stability theorem.
A novel method of improving coupling effiency of laser diode based on synthesized lens with graduaed index fiber
Authors: Yan Feng-Ping  , Liu Peng  , Tan Zhong-Wei  , Tao Pei-Lin  , Li Qi  , Peng Wan-Jing  , Feng Ting  , Tan Si-Yu  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China;,   Key Laboratry of All Optical Networks and Advanced Communication Networks, Ministry of Education, Beijing 100044, China;,   Physics Department of Xingtai College, Xingtai 054001, China
Published: December 2020

In this paper, a novel method of improving coupling effiency of laser diode to single mode fiber based on synthesized lens with graduaed index fiber is provided. The output beam with large astigmatism from laser diode is shaped and focused via synthesized lens and graduaed index fiber, and then couplied into single mode fiber. Analysis using Jones matrix theory indicates that the power coupler effect of 86% is obtained from output port of the single mode fiber. The tolerances for fiber length of graduaed index fiber, radial offset and tilt degree are 60 m, 30 m and 2.4 degree respectivily for 1 dB insert loss. This method can be used for improving the quality of optical beam and increasing output power for laser diode to single mode fiber with a large output optical power.
Analysis of absorption property for pumping laser with double cladding rare earth doped fiber
Authors: Yan Feng-Ping  , Liu Peng  , Tao Pei-Lin  , Li Qi  , Peng Wan-Jing  , Feng Ting  , Tan Si-Yu  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China;,   Key Laboratory of All-Optical Networks and Advanced Communications Networks, Ministry of Education, Beijing 100044, China;,   Physics Department of Xingtai College, Xingtai 054001, China
Published: December 2020

In this paper, a pump laser absorption model for double cladding rare earth doped optical fiber is established by using the finite difference beam propagation method combined with complex refractive index profile, and the absorption properties are analyzed in detail for some typical inner cladding structures by using this model. The results can be used to design the double cladding rare earth doped optical fiber.
Fractal analysis of Herschel-Bulkley fluid flow in a capillary
Authors: Yun Mei-Juan  , Zheng Wei  , Li Yun-Bao  , Li Yu  ,   Key Laboratory of Systems Science in Metallurgical Process of Hubei Province, Wuhan University of Science and Technology, Wuhan 430081, China;,   State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China;,   State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China
Published: December 2020

A fractal model for Herschel-Bulkley fluid in a capillary is proposed based on the fractal theory. The proposed model relates flow rate, velocity, starting pressure gradient and effective permeability to the rheological characteristics of fluid and the structural parameters of capillary, and all parameters in the proposed expressions have clear physical meanings. The analytical expressions reveal the physical principle for Herschel-Bulkley fluid flow in a capillary.
Suppression of visible light emission of ZnO nanostructures by Ga-doping
Authors: Shen Qing-He  , Gao Zhi-Wei  , Ding Huai-Yi  , Zhang Guang-Hui  , Pan Nan  , Wang Xiao-Ping  ,   Department of Physics University of Science and Technology of China, Hefei 230026, China;,   Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Ga-doped ZnO nanostructures with various doping concentrations are prepared by using carbon thermal reduction reaction and in situ doping method. X-ray diffraction measurement reveals only wurzite structures existing in Ga-doped ZnO nanostructures. Scaning electron microscopy observations show that with the increase of Ga doping concentration, the morphology of ZnO nanstrucuture varies gradually from nanorods to nanocones. From the photoluminescence, we find that the visible light emission of ZnO nanostructures can be suppressed obviously and even disappears with the increase of Ga doping concentration. Moreover, the suppression of visible light emission is correlated well with the behavior, and X-ray photoelectron spectroscopy measurement reveals that the vacancy oxygen in ZnO nanostructure decreases drastically with the increase of Ga doping concentration. This result offers a new strong evidence for the mechanism that the visible light emission of ZnO nanostructures is caused by the oxygen vacancy defects. This work also demonstrates that a little Ga incorporation into ZnO nanostructures can effectively reduce the oxygen vacancy defects occurring.
Linear analysis of open-style dielectric-lined azimuthally periodic circular waveguide
Authors: Liu Yang  , Wei Yan-Yu  , Shen Fei  , Xu Xiong  , Lai Jian-Qiang  , Huang Ming-Zhi  , Tang Tao  , Gong Yu-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 novel slow-wave structure, i.e., an open-style dielectric-lined azimuthally periodic circular waveguide (open-style DLAP-CW) which can be applied to millimeter wave traveling-wave tube, is proposed. The hot dispersion characteristics are derived by the self-consistent relativistic field theory. And the electron beam interaction in the novel slow-wave structure (SWS) is analyzed in a linear frame. The linear gain characteristics of the DLAP-CW is studied analytically for dimensions of the improved SWS and the parameters of the electron beam. The results illustrate that selecting the appropriate dimensions of the metal rods can improve the small-signal gain. Finally, a comparison of the small-signal gain of this structure with a close-style DLAP-CW is made, and the results validate that the novel SWS has an advantage over the close-style DLAP-CW in gain with little influence on the bandwidth, which can potentially improve electron efficiency in the beam wave interaction. The research in this paper will also be a foundation of the theory for open-style dielectric-lined azimuthally periodic circular waveguide traveling-wave tube.
Experimental investigation of different Bell-type inequality in three-qubit Greenberger-Horne-Zeilinger states
Authors: Zhao Jia-Qiang  , Cao Lian-Zhen  , Wang Xiao-Qin  , Lu Huai-Xin  ,   Shandong Provincial Key Laboratory of Multi-photon Entanglement and Manipulation, Department of Physics and Electronic Science, Weifang University, Weifang 261061, China
Published: December 2020

We investigate experimentally the violation of the Bell, Mermin and Svetlichny inequalities to local realism prediction. Using the maximum-likelihood technique to construct the density matrix and calculate the fidelity of the Greenberger-Horne-Zeilinger (GHZ) state. The values of the three inequalities are measured. The experimental resuls show that the three inequalities have different violation degrees to local realism prediction. So we can choose a suitable method of nonlocality to estimate the security of quantum channel.
The resonant behavior of an over-damped linear fractional Langevin equation
Authors: Zhong Su-Chuan  , Gao Shi-Long  , Wei Kun  , Ma Hong  ,   College of Mathematics, Sichuan University, Chengdu 610065, China;,   Sichuan University Jincheng College, Sichuan University, Chengdu 611731, China;,   College of Mathematics and Information Science, Leshan Normal University, Leshan 614000, China
Published: December 2020

By choosing the internal noise as a fractional Gaussian noise, we obtain the fractional Langevin equation. We explore the phenomenon of stochastic resonance in an over-damped linear fractional Langevin equation subjected to an external sinusoidal forcing. The influence of fluctuations of environmental parameters on the dynamics of the system is modeled by a dichotomous noise. Using the Shapiro-Loginov formula and the Laplace transformation technique, we obtain the exact expressions of the first and second moment of the output signal, the mean particle displacement and the variance of the output signal in the long-time limit t→∞. Finally, the numerical simulation shows that the over-damped linear fractional Langevin equation reveals a lot of dynamic behaviors and the stochastic resonance (SR) in a wide sense can be found with internal noise and external noise.
STM study of single cobalt atoms and clusters adsorbed on Rh (111) and Pd (111)
Authors: Feng Wei  , Zhao Ai-Di  ,   Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

We investigate the adsorption and electronic properties of single cobalt atoms and clusters adsorbed on Rh (111) and Pd (111) with scanning tunneling microscopy and scanning tunneling spectrum (STM/STS). It is found that there are two apparent heights for individual cobalt atoms on Rh (111), corresponding to Co atoms adsorbed hcp and fcc hollow sites. The Co atoms on both sites exhibit a notable peak near the Fermi energy, and the two peaks have a slight difference in peak shape. By fitting the dI/dV spectrum to the Fano lineshape, we find that the peak cannot be simply ascribed to the Kondo model. The peak position and full width at half maximum of the peak suggest that the magnetic impurity is in the mixed-valence regime rather than in the Kondo regime. And the peak can be interpreted as a combination of the Kondo resonance and bare d resonance. For Co dimers and trimers on Rh (111), there is no observable feature in their dI/dV spectra near the Fermi level. This is speculated to be due to the magnetic exchange interaction and orbital hybridization between Co atoms. For Co single atoms adsorbed on Pd (111) surface, only one apparent height is found, suggesting that it is due to a different interaction from Co on Rh (111) surface. We do not find notable feature near the Fermi level in the dI/dV spectra of all Co monomers, dimers and trimers.
The study on the stress and the friction coefficient of tetrahedral amorphous carbon films bombarded by energetic Ar ion
Authors: Han Liang  , Ning Tao  , Liu De-Lian  , He Liang  ,   School of Technical Physics, Xidian University, Xi'an 710071, China;,   Construction Engineering Research Institute of the Department of Logistics, P.L.A, Xi'an 710049, China
Published: December 2020

The ta-C films with sp3 bonds more than 80% in fraction are deposited by FCVA technique, and then they are bombarded by Ar ions. The composition and structures of the ta-C films before and after the bombardment of energetic Ar ions are analyzed by X-ray photoelectron spectroscopy. The surface morphology is investigated by AFM. The result shows that the bombardment of Ar ions induces the conversion of sp3 bond into sp2 bond, and the fraction of sp2 bonds increases with the energy of Ar ion increasing. The stress of the film decreases with the increase of the Ar ion energy. The RMS and etching pits on the surface of film increase with the increase of Ar ion bombarding energy.The friction test indicates that Ar ion bombardment has an important influence on initial friction coefficient, but just has little influence on steady state friction coefficient. The steady state friction coefficient of film keeps about 0.1, which shows a good antiwear property.
The electronic theory study on high-temperature oxidation mechanism of TiAl alloy
Authors: Liu Gui-Li  , Li Yong  ,   School of Constructional Engineering, Shenyang University of Technology, Shenyang 110023, China
Published: December 2020

In order to reveal the physical nature of high temperature oxidation of titanium-aluminous alloy from the electronic level, the atom embedded energy, affinity energy, binding energy and other electronic structure parameters are calculated by using recursive method combining with Castep, and the alloy oxidation mechanism is explored. The results show that there is a larger oxygen solubility in titanium and oxygen atoms can aggregate into titanium matrix near surface, and gradually spread into the deep matrix. Oxygen and titanium have a strong affinity to form a titanium oxide film. Aluminum can form clusters with mutual attraction between aluminum atoms in titanium matrix. Titanium atoms in aluminum clusters are mutually repulsive and form chemical compounds with aluminum atoms. Because of the closing affinity energy between aluminum and titanium with oxygen, the preferential oxidation of aluminum cannot occur, but titanium oxide and aluminum oxide form. The binding energy of Al2O3 is slightly lower than that of TiO2, therefore Al2O3 is more stable. Aluminum in TiO2 has a greater solubility, which can replace titanium to form more stable oxide Al2O3.
Study on SQUID method and Campbell method measure superconductors
Authors: Guo Zhi-Chao  , Suo Hong-Li  , Liu Zhi-Yong  , Liu Min  , Ma Lin  ,   The Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The two magnetic measurement methods of superconductors, SQUID method and Campbell method, are introduced briefly. Superconducting properties of MgB2 bulk samples are prepared by the high-pressure powder in tube (PIT) sintering method. The two measurement methods are employed to measure the critical current density of the sample. The Jc-B curves of the MgB2 samples are obtained with each method. The SQUID method can be used to measure the magnetic strength field up to 6 T and the material is in normal state, and the result is used to scale F(b) of the pinning through necessary calculation which is used to study the magnetic characteristic of the material. The critical current density (Jc) measured by the SQUID method is the average of the materials different parts. Jc is measured and estimated by the Campbell's method. The magnetic field is only to 0.4 T while the frequency of the AC parts magnetic field is varied from 37 Hz to 797 Hz. The critical current density obtained by Campbell's method is smaller than that obtained by the SQUID measurement, which is due to the existence of various faults and the decrease of the electrical connectivity.
Design and simulation of 140 GHz high power staggered double vane traveling-wave tube
Authors: Lai Jian-Qiang  , Wei Yan-Yu  , Xu Xiong  , Shen Fei  , Liu Yang  , Huang Min-Zhi  , Tang Tao  , Gong Yu-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

Staggered double vane slow wave structure (SWS) and sheet electron beam are employed to investigate a 140 GHz high power traveling wave tube. Numerical calculation of eigenmode shows that the SWS has a good characteristic of dispersion and interaction impedance. The transition structure, input/output coupler and concentrated attenuator are especially proposed for the circuit to ensure that the tube will work well. Particle-in-cell simulation results demonstrate that the traveling wave tube can provide over 300 W of peak power in a frequency range of 132-152 GHz with a maximum of 546 W and a corresponding gain of 37.37 dB at 138 GHz assuming a beam power to be 5.115 kW and input power to be 0.1 W. The output power of the tube can exceed 440 W in a frequency range of 128-152 GHz with a corresponding interaction efficiency of over 8.6% when the input powers range from 0.027 W to 0.46 W. Such a traveling wave tube has a great significance and a potential application in high power short millimeter wave field.
Research and discussion on the lock-in threshold variation of ring laser gyro
Authors: Fan Zhen-Fang  , Luo Hui  , Lu Guang-Feng  , Hu Shao-Min  ,   College of Optoelectronic Science and Technology, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The lock-in threshold can be obtained by reducing the rotation rate. The lock-in threshold obtained using this method is inconsistent with the angle random walk derived from Allan variance. A dynamic burn-in grating model is proposed. The burn-in effect happens in the mirror not only in the standing wave state, but also in the traveling wave state, and it responds dynamically to beat frequency, which is different from previous research results. It can be derived that the lock-in threshold increases with the decrease of rotation rate for this model, and many puzzling phenomena of the ring laser gyro can be explained.
Study of coupled fluid and solid for a hypersonic lending edge
Authors: Nie Tao  , Liu Wei-Qiang  ,   Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Coupled simulation of hypersonic flow and heat exchange is investigated. Moreover, structural stress based on pseudo static assumption is also studied. The unsteady Navier-Stokes equations are solved for the flow field, and SST k-ω model is used as the turbulent model. The unsteady heat conduction equation is solved for the structure. At the fluid-structure interface the flow field acquires temperature boundary condition from the structure and the structure temperature field obtains heat flux boundary condition from flow field. The method proposed here is proved by the slipstream experiment of the infinite circular pipe. The transformation of the temperature and stress of the two-dimensional circular pipe is analyzed in detail during aerodynamic heating. The results show that the high temperature field is gradually enlarged with the increase of aerodynamic heating time. At the same time the structural thermal strain is also gradually enhanced. The minimal deformed area will appear when θ is equal to 60°. The thermal deformation of circular pipe has very little effect on the flow field.
Structural and electronic properties of Al-doped spinel LiMn2O4
Authors: Gao Tan-Hua  , Liu Hui-Ying  , Zhang Peng  , Wu Shun-Qing  , Yang Yong  , Zhu Zi-Zhong  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China;,   School of Science, Jimei University, Xiamen 361021, China;,   Department of Physics, Xiamen University, Xiamen 361005, China;,   State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China;,   Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University, Xiamen 361005, China
Published: December 2020

The structural and electronic properties of spinel LiMn2O4 and its Al doping system LiAl0.125Mn1.875O4 are investigated within the density functional theory in both the generalized gradient approximation (GGA) and the GGA with Hubbard U correction (GGA+U). The results from the GGA method suggest that LiMn2O4 has a cubic structure and the valences of Mn ions are all +3.5, which is unable to explain the Jahn-Teller distortions in the material. The band structure of LiMn2O4 predicted by the GGA method is also inconsistent with experimental result. With the GGA+U method, the low temperature structures of LiMn2O4 and its Al doping system LiAl0.125 Mn1.875O4 are shown to be orthogonal, the two different valence states of Mn, i.e., Mn3+/Mn4+ ions, are then determined, which is then able to explain the Jahn-Teller distortion in octahedron Mn3+O6 and the non-existence of distortion in octahedron Mn4+O6. These results are in good accordance with experimental data. Their band structures by GGA+U calculations are also consistent with experimental results. The GGA+U calculations on the LiAl0.125Mn1.875O4 indicate that with the replacement of an Mn by Al, the crystal structure and electronic properties are not significantly changed, but the Jahn-Teller distortion in octahedron Al3+O6 can be effectively eliminated, which could improve the performance of the anode materials based on LiMn2O4. The phenomenon is in consistent with the electrochemical experiments.
The nonreciprocal of second harmonic generation with dielectric/antiferromagnetic/dielectric structure in Voigt geometry
Authors: Zhou Sheng  , Wang Xuan-Zhang  , Fu Shu-Fang  , Li Qiang-Hua  , Qu Xiu-Rong  , Liang Shuang  , Zhang Qiang  ,   Heilongjiang Key Laboratory for Photonic and Electric Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China;,   Department of Physics, School of Physics, Nanjing Universty, Nanjing 210093, China
Published: December 2020

We calculate the second harmonic generation (SHG) from structures with dielectric/antiferromagnetic(AF)/dielectric in Voigt geometry. The calculations are performed with a nonlinear transfer matrix method and examples of nonreciprocal SHG are given. In particular, we study the nonreciprocal SHG in four different configurations when the direction of an applied magnetic field and the order of dielectric films are reversed. The nonreciprocal SHG can be realized in a resonance zone of AF, including THz frequency range. The increasing of the angle of incidence wave can enhance the effect of nonreciprocal SHG. In terms of applications, AF may be of interest in signal processing in the THz.
A modified method to configure the parameters of the bilateral filtering for synthetic aperture radar image speckle reduction
Authors: Li Jin-Cai  , Huang Bin  , Peng Yu-Xing  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China;,   Department of Computer Science, Huaihua College, Huaihua 418008, China
Published: December 2020

Bilateral filtering can effectively smooth synthetic aperture radar (SAR) images with preserving the edges, but it is difficult to configure the parameters of bilateral filtering to the optimum. The iterative method to configure the parameters with high precision and efficiency has been presented, but the iterative process may be aborted incorrectly. In this paper, we present a modified configuration method to get the optimal trade-off parameters, and give the proof of the convergence of the method. The experimental results on real SAR images show that the modified method can not only obtain equivalent visibility as the iterative method, but also higher accuracy of the gray value similarity variance than that under identical iterative precision. With the iterative precision improved, the convergence rate of the modified method is faster than that of the iterative method.
Structural modeling of 128× 128 InSb focal plane array detector
Authors: Meng Qing-Duan  , Zhang Xiao-Ling  , Zhang Li-Wen  , Lü Yan-Qiu  ,   School of Electronic Information Engineering, Henan University of Science and Technology, Luoyang 471003, China;,   China Airborne Missile Academy, Luoyang 471009, China
Published: December 2020

Higher fracture probability appearing in InSb infrared focal plane array (IRFPA) subjected to thermal shock test, restricts its final yield. In order to understand the fracture mechanism, in light of the proposed equivalent method, where a 32× 32 array is employed to replace the real 128× 128 array, to a three - dimensional structural model of IRFPA is developed by taking into account the temperature dependence of thermal expansion coefficient, anisotropic mechanical strength of InSb chip, damaging effects of the surface of the InSb chip, and a reduction of 90% the out-of-plane elastic modulus. Simulation results show that a maximum Von Mises stress appears in the N electrode zone in InSb chip, and the extremum values present a non-continuous distribution. This means that the cracks is most likely to emerge in the region of N electrode, besides, the number of crack tracks is more than one. These are well consistent with the 128× 128 InSb IRFPA fracture statistics results under thermal shock test. All these are beneficial to the further study of fracture inducing factors and structural reliability design of InSb IRFPA.
Simulation of photonic crystal fiber with three and four zero-dispersion wavelengths
Authors: Zhao Xing-Tao  , Zheng Yi  , Liu Xiao-Xu  , Liu Zhao-Lun  , Li Shu-Guang  , Hou Lan-Tian  ,   Laser Institute of Science College, Beijing Jiaotong University, Beijing 100044, China ;,   Measurement Technology and Instrumentation Key Lab of Hebei Province, State Key Lab of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;,   College of Physics and Chemistry, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China
Published: December 2020

The dispersion characteristics of photonic crystal fibers are computed using the multipole method. Single-mode fiber with three zero-dispersion wavelengths is obtained by properly designing fiber structure parameters. The dispersion characteristics of photonic crystal fiber with a small air hole in the core are analyzed. Fibers with four zero-dispersion wavelengths are designed. The variation rules of zero-dispersion wavelength with fiber structure parameter are found. The locations and spacings of the zero-dispersion wavelengths can be adjusted flexibly in a large wavelength range. Closing to zero and flattened dispersion can be obtained in the fibers with multiple zero-dispersion wavelengths. The multiple zero-dispersion wavelengths can create a rich phase-matching topology, and enable better controlling the spectral locations of the four-wave-mixing and resonant-radiation bands emitted by solitons and short pulses.
The structural transition of water at quartz/water interfaces under shock compression in phase region of liquid
Authors: Wang Jun-Guo  , Liu Fu-Sheng  , Li Yong-Hong  , Zhang Ming-Jian  , Zhang Ning-Chao  , Xue Xue-Dong  ,   Institute of High Pressure and High Temperature Physics, Southwest Jiaotong University, Chengdu 610031, China;,   Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China
Published: December 2020

We investigate the structural transformations of water at the water/quartz interface under shock compression in ranges from 0.5 to 2 GPa and from 335 to 375 K by techniques of a gas-gun and light transmission tests. The results show that the structural transformation of water occurs in the region of liquid phase, which starts from water/quartz interface at high pressures and temperatures. The transformation rate is related to the property of quartz interface. This structural evolution indicates that a lager number of water molecules undergone transitions in equilibrium behavior. The kinetic process of liquid water structure can be divided into four stages while the structure continues growing to saturation. This new mechanism of structural transformation has immediate implications for water structure transformation in diverse natural environments.
The effects of spinodal decomposition and nucleation on phase separation
Authors: Ren Qun  , Wang Nan  , Zhang Li  , Wang Jian-Yuan  , Zheng Ya-Ping  , Yao Wen-Jing  ,   Key Laboratory of Space Applied Physics and Chemisty, Ministry of Education, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

Spinodal decomposition and nucleation process are realized by using three transparent solutions: SCN-30 wt%H2O, SCN-50 wt%H2O, and SCN-80 wt%H2O, and the migration characteristics of minor phase droplets (MPDs) was investigated when uni-direction temperature field is applied. It is find that spinodal decomposition takes place in SCN-50 wt%H2O system and nucleation processes occur in SCN-30 wt%H2O and SCN-50 wt%H2O systems. The period during which the minor droplets of the same size in spinodal decomposition are formed is 1/3—1/2 of that in nucleation process. Moreover, the temperature interval in the system with critical composition is larger than those in other systems, therefore, the minor phase droplet formed in spinodal decomposition is longer than that in nucleation process. Under uni-direction temperature field conditions, the migration velocity of MPDs in SCN-80 wt%H2O system is measured experimentally. It is revealed that the experimental results agree well with the calculated Marangoni velocity, indicating that the Marangoni migration plays a key role in the motion of MPDs.
Nonlinear Ramsey interference of Fermi superfluid gases in unitarity regime
Authors: Meng Hong-Juan  , Gou Xue-Qiang  , Wang Wen-Yuan  , Yang Yang  , Ma Ying  , Ma Yun-Yun  , Duan Wen-Shan  ,   Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

We investigate the relationships between the nonlinear Ramsey interference pattern of the angular frequency and system parameters of fermi superfluid gase in unitarity regime in three limited cases. We find that the interaction between fermions and the difference in energy between double-well potentials have a significant influence on the angular frequency of the interference pattern. Through numerical simulation and theoretical analysis, the relationship between angular frequency of the interference pattern and the system parameters is given, and the numerical simulations and theoretical analyses are in good agreement.
The effects of Ti ion-irradiation on critical current and flux pinning in MgB2 thin film
Authors: Wang Yin-Bo  , Xue Chi  , Feng Qing-Rong  ,   Application Superconductivity Research Center, State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

High-quality MgB2 films are fabricated via hybrid physical-chemical vapor deposition (HPCVD) and irradiated by Ti ions. Compared with the unirradiated film, the Ti-irradiated MgB2 film shows a high critical current density (Jc) in magnetic field and also a high upper critical field (Hc2), while the superconducting transition temperature (Tc) does not decrease significantly. The Ti-irradiated film with a best fluence at 1 1013/cm2 shows a high Jc of 1.72 105 A/cm2 in 4 T perpendicular field at a temperature of 5 K and a moderately decreased Tc at 39.9 K.
Preparation and performances of KNN-based lead-free transparent ceramics
Authors: Wang Bin-Ke  , Tian Xiao-Xia  , Xu Zhuo  , Qu Shao-Bo  , Li Zhen-Rong  ,   Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   College of Science, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

Using conventional solid-phase sintering technique combined with a special atmosphere controlling technique, KNN-based lead-free transparent ceramics, xBa(Sc0.5Nb0.5)O3-(1-x) (K0.5N0.5)NbO3 (xBSN-(1-x) KNN), are prepared and investigated. Their microstructure, dielectric performance, ferroelectric performance and optical transparency are investigated. The results show that such ceramics are each with a pseudocubic-Perovskite structure, without any other impure phase. Their grain size is comparable to the light wavelength and the grains are highly condensed without evident crystal borders. For x=0.05, the d33 reaches up to 110 pC/N maximally and the 2Pr =25.4 C/cm2. Moreover, such ceramics are each with an excellent transparency. Their optical transparency reaches about 54%, In the near-infrared wavelength 2500 nm, their optical transparency is near 83%. Such ceramics are a type of environment-friendly lead-free transparent ceramics which may be promising in replacing lead-based transparent ceramics.
Research on the entropy of logistic chaos
Authors: Pan Xin-Yu  , Zhao He-Ming  ,   School of Electronics and Information Engineering, University of Science and Technology of Suzhou, Suzhou 215011, China;,   School of Electronics and Information Engineering, Soochow University, Suzhou 215021, China
Published: December 2020

As a simple one-dimensional chaotic system, logistic map has some important applications in many fields. The stable entropy characteristic of logistic function is proposed in this paper. A series of logistic sequence entropy, calculated under different initial values and values of parameter μ, is found to have some special distributions. A great number of numerical simulations prove that the entropy is determined by parameter μ, and it is irrelevant with initial value. The logistic sequence becomes a uniform distribution, and its entropy is close to a maximum, when μ is increased to 4. Thereby the stationary quality of logistic chaos can be speculated to some extent.
Bifurcations in coupled electrical circuit systems
Authors: Li Qun-Hong  , Yan Yu-Long  , Yang Dan  ,   College of Mathematics and Information Science, Guangxi University, Nanning 530004, China
Published: December 2020

A coupled system composed of two nonlinear circuit systems is investigated. In this paper, the existence condition and the analytical expressions of equilibrium in higher-dimensional system are derived, and the co-dimension 1 and co-dimension 2 bifurcations of equilibrium are also studied. Furthermore, the complicated bifurcations are obtained through the continuation of limit cycles. It may lead to various dynamical behaviors such as periodic motion, chaos, etc., for the interaction of two subsystems with periodic motions under different coupling parameters. Using the qualitative analysis of equilibrium before and after coupling, the relation between the discontinuity of bifurcation diagram and occurrence of neutral saddle in the case of weak coupling is presented.
Optical model potential of antiproton atoms with nuclear polarization correction
Authors: You Yang-Ming  , Wang Bing-Zhang  , Wang Ji-You  ,   Deparment of Physics and Electron Information, Cangzhou Teachers' College, Cangzhou 061001, China;,   Department of Machine and Electric Power Engineering, Cangzhou Teachers' College, Cangzhou 061001, China;,   College of Applied Sciences, Beijing University of Technology, Beijing 100022, China
Published: December 2020

According to SIC-X, a more rigorous calculating method, we propose a self-consistent field mode with the Rydberg exchange parameters. Using this method to calculate nuclear polarization, the result is more accurate than that given by Chen et al. Besides, when they calculated P238U energy level transition, their model is likely to be imperfect and maybe has some defects that are hard to overcome. And their result is likely to be inaccurate. In the early 70s of 20th century, Batty performed the exploration of optical model potential, and after more than twenty times of exploring and improving, he finally presented a correct form of optical model potential. When a self-consistent field model for Rydberg exchange parameters is used to calculate nuclear polarization, we use this method to correct Batty's nuclear polarization under optical model potential and the P238U energy level transition. We obtain the energy levels of antiproton atoms. The result is exactly the same as the experimental result. This result together with the case of -, K-, - and - atoms supports the correctness of optical model potential of Batty's description of the strong interaction between nucleons. At the same time, it also shows the correctness of the method of calculating nuclear polarization. It provides a theoretical basis for further study and application of antiparticle atoms and exoticac atoms.
Numerical implementation of deformation and motion of droplet at the interface between vapor and solid surface with smoothed particle hydrodynamics methodology
Authors: Qiang Hong-Fu  , Liu Kai  , Chen Fu-Zhen  ,   Staff Room, Xi'an Hi-Tech Institute, Xi'an 710025, China
Published: December 2020

In order to simulate the deformation and motion of droplet at the interface between vapor and solid surface, the smoothed particle hydrodynamics method with continuum surface force model for surface tension is modified in this paper. A surface tension algorithm with boundary conditions of wall adhesion is derived using a new treatment of boundary conditions and a corrective algorithm of particle interface normal. The colours of virtual solid particles are set according to the position of fluid surface to assure that the interface normal of particles at the junction of vapor, fluid and solid phase is normal to the contact line. By introducing Brackbill's treatment of boundary conditions of wall adhesion, the interface normal between fluid particles and some virtual solid particles at the junction of vapor, fluid and solid phase is corrected. However the module of the interface normal is kept constant. Finally, based on the new algorithm, the changing process of fluid surface in a tank, wetting process of a droplet and distortion process of a droplet on solid surface driven by shear flow are simulated. The results are compared with those obtained by volume of fluid method, showing that the new method has higher accuracy and better stability, and it is adapted to deal with the engineering problems such as the deformation and motion of droplets at the interface between vapor and solid surface.
Ejecta on Pb surface below and above melting pressure
Authors: Chen Yong-Tao  , Ren Guo-Wu  , Tang Tie-Gang  , Li Qing-Zhong  , Wang De-Tian  , Hu Hai-Bo  ,   Laboratory for Shock Wave and Detonation Physical Research, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In this paper, Asay-F-window diagnostic technology for high density and large mass ejecta measurement is designed. By Asay-F-window technology, the mass and the density-velocity distribution of ejecta from Pb surface are presented. The difference in ejecta between below and above Pb melting pressure is particularly studied. Moreover, the physical causation inducing the ejecting difference is well explained through theory analysis.
Theoretical study on boundary distributions and flow-metal heat transfer during melt treatment by cooling sloping plate
Authors: Guan Ren-Guo  , Zhao Zhan-Yong  , Huang Hong-Qian  , Lian Chao  , Chao Run-Ze  , Liu Chun-Ming  ,   College of Materials and Metallurgy, Northeastern University, Shenyang 110004, China
Published: December 2020

In this paper, according to the principle of grain refining and semisolid forming by cooling sloping plate process, the distributions of boundary layers during melt treatment by the sloping plate are studied, and mathematic models of heat transfer and cooling rate are established. Calculation results show that the change time from laminar flow to turbulent flow decreases with the increases of the sloping angle and initial flow velocity. The thickness of temperature boundary layer decreases with the increases of initial flow velocity. The effect of the sloping angle on the thickness of temperature boundary is small. The boundary layer thicknesses of the both temperature and velocity increase with the increase of the flow distance gradually. In the laminar flow region, the thickness of the temperature boundary layer is much bigger than that of the velocity boundary layer, while the two layers coincide with each other in the turbulent flow zone. The melt cooling rate on the sloping plate and the melt thickness have an inverse proportion relationship between each other. When the initial flow velocity is lower than 1 m/s the cooling rate increases along the sloping plate gradually. While the initial flow velocity is 1 m/s, the cooling rate dose not change approximately. However, when the initial flow velocity is larger than 1m/s the cooling rate decreases along the sloping plate gradually. The melt cooling rate on the cooling sloping plate is between 100 K/s and 1000 K/s, which belongs to meta-rapid solidification scope.