bluuebunny/crossref_metadata_2025 huggingface dataset:
Large partial band-gaps for Lamb waves in multiple phononic crystals thin plates
Authors: Ding Hong-Xing  , Shen Zhong-Hua  , Li Jia  , Zhu Xue-Feng  , Ni Xiao-Wu  ,   School of Science, Nanjing University of Science and Technology, Nanjing 210094, China;,   Department of Physics, Lianyungang Teachers College, Lianyungang 222006, China;,   Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

During the past decade, a growing attention has been paid to the Lamb waves propagating in composite plates due to a variety of applications for nondestructive evaluation, vibration attenuation and Lamb wave sensors. We present a revised plane wave expansion method and a finite element method to study the large partial band-gaps of a multiple Lamb wave phononic crystal thin plate with a symmetric mirror plane The results show that lots of partial stopbands of lower-order Lamb waves exist and can be substantially enlarged by using multiple heterostructures which consist of several pieces of phononic crystal with different ratios of the thickness (H) to the lattice period (L). These contribute to good mode choice for lower-order Lamb waves, which is believed to have much significance for optimially choosing models in Lamb wave nondestructive test and the one-way Lamb wave mode transmission.
Effect of oxygen content on giant dielectric constant and dielectric process in CaCu3Ti4O12
Authors: Yang Chang-Ping  , Li Min-Yi  , Song Xue-Ping  , Xiao Hai-Bo  , Xu Ling-Fang  ,   Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China
Published: December 2020

Dielectric properties of three different CaCu3Ti4O12 ceramic samples sintered, respectively, in vacuum, air and oxygen are investigated. Three plateaus are detected in the dielectric temperature spectra within 10—300 K for all the three samples, meanwhile the three corresponding peaks of the real impedance and imaginary capacitance occur at a certain temperature. However, the sample sintered in vacuum presents a higher dielectric and clearer real impedance and imaginary capacitance peak, which indicates that oxygen concentration and oxygen vacancy have a great influence on the dielectric property of CaCu3Ti4O12. The results reveal that the three plateaus observed in the dielectric temperature spectra come from the grain, grain boundary and the oxygen vacancy sitting in grain boundary, respectively. The analysis of dielectric spectra indicates that the activation energy of the grain is related to the sintering atmosphere and the oxygen vacancy results in a variable-range-hopping conductivity and polarization for the grain. The activation energy of oxygen vacancy trapper is about 0.46 eV and is nearly independent of sintering atmosphere. The high dielectric constant at low-frequency or high temperature is caused by oxygen vacancy trapping carriers in CaCu3Ti4O12.
Effect of annealing on crystalline property of poly-Si thin-film by Ge-induce crystallization
Authors: Kang Kun-Yong  , Deng Shu-Kang  , Shen Lan-Xian  , Sun Qi-Li  , Hao Rui-Ting  , Hua Qi-Lin  , Tang Run-Sheng  , Yang Pei-Zhi  , Li Ming  ,   Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Solar Energy Research Institute, Yunnan Normal University, Kunming 650092, China
Published: December 2020

In this paper, an a-Si/Ge thin film with a buried layer of Ge and an a-Si thin film are prepared on Si substrates at a temperature of 500 ℃ by magnetron sputtering. The prepared films are annealed for 5h at different temperatures in vacuum. The annealed films are characterized by Raman scattering, X-ray diffraction, atomic force microscope and field emission scanning electron microscope. The results reveal that Ge can induce amorphous Si (a-Si) growing at a temperature of 500 ℃ by magnetron sputtering crystallize after annealing at a temperature of 600 ℃ for 5h. And in the a-Si/Ge thin film the degrees of crystallization of a-Si are 44% and 54% at the annealing temperatures of 600 ℃ and 700 ℃, respectively. By comparison, a-Si thin film without Ge is crystallized at an annealing temperature of 800 ℃ for 5h and the degree of crystallization is 46%. The crystallization temperature of a-Si/Ge is reduced by 200 ℃ compared with that of a-Si film without buried Ge layer in the film. The prepared poly-Si thin film possesses high Si(200) orientation with a grain size of 76 nm. The preparation of poly-Si film by Ge-induced crystallization might be a useful technology for developing high-quality poly-Si film.
A big cluster model of the PER-TIM interval timer in drosophila cytoplasm for the circadian clock
Authors: Zhang Zhi-Qiang  , Li Cong-Xin  , Xie Ping  , Wang Peng-Ye  ,   Key Laboratory of Soft Matter Physics, Beijing National Laborartory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China
Published: December 2020

Circadian rhythm makes physiology and behaviors of organisms adapt to the day and night cycle in the environment. Recent experiment indicated a PER-TIM interval timer in Drosophila melanogaster cytoplasm. In this paper, we present a possible mathematical model for this interval timer. The characters of the model are the formation of big clusters, fast exchange and different functions of phosphorylation of different sites. The experimental results on features of the PER-TIM interval timer of mild type and perL mutant and on the existence of three different types of temporal profiles of nuclear accumulation of PER and TIM in single cells are reproduced by our simulations.
Raytracing of extreamely low frequency waves radiated from ionospheric artificial modulation at low latitude
Authors: Wang Feng  , Zhao Zheng-Yu  , Chang Shan-Shan  , Ni Bin-Bin  , Gu Xu-Dong  ,   Departmen of Optoelectronic Information, School of Electronic and Electrical Engineering, Wuhan Textile University, Wuhan 430200, China;,   Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430079, China
Published: December 2020

Powerful high-frequency radio waves modulated at extremely low frequency (ELF) and very low frequency (VLF) can efficiently modify the lower ionospheric current which can act as an equivalent ionospheri'c antenna for the generation of ELF/VLF wave and these signals can propagate into the magnetosphere and the investigation of the propagation properties is of significance for understanding of radiation belt energetic electrons precipitation. In this paper, based on the raytracing theory, the ray paths of ELF waves in the magnetosphere are obtained using numerical modeling and the properties are analyzed. The results shows that the ELF waves generated from the low latitude reflect between the southern and northern hemisphere and propagate to the farther place gradually. For the signals with different frequencies, the higher their frequencies, the shorter their propagation distances are, the lower their frequencies, the longer their propagtion distances are. In the process, ELF waves tend to reflect near a fixed region. The normal angel increases to 90° gradually and ray direction tends to propagate along the direction of geomagnetic field.
A type of new conserved quantity of Mei symmetry for Appell equations in a holonomic system
Authors: Sun Xian-Ting  , Han Yue-Lin  , Wang Xiao-Xiao  , Zhang Mei-Ling  , Jia Li-Qun  ,   School of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China;,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

A type of new conserved quantity of Mei symmetry for Appell equations in a holonomic system is investigated. Based on the definition and criterion of Mei symmetry for Appell equations in a holonomic system, a type of new structural equation and new conserved quantity of Mei symmetry for Appell equations in a holonomic system expressed by Appell function under the infinitesimal transformations of groups are obtained. An example is given to illustrate the application of the results.
Unsteady dynamic evolution adjoint design method
Authors: Gao Ying-Ying  , He Feng  , Shen Meng-Yu  ,   School of Aerospace, Tsinghua University, Beijing 100084, China
Published: December 2020

On the basis of studying the traditional adjoint method based on the steady flow solution and the steady solution of the adjoint equation, a new optimal aerodynamic design method called the dynamic evolution adjoint method is presented in this paper. This new method is based on the instantaneous solution of the unsteady flow governing equation and the instantaneous solution of the unsteady adoint equation. The dynamic evolution adjoint method has the advantage of both the adjoint method and the dynamic evolution method. The numerical results of many examples show that this new method is much more time saving than the traditional adjoint method and the accuracy of this new method can be the same as that of the traditional adjoint method.
Dynamical patterns of epidemic outbreaks on scale-free networks with traffic flow
Authors: Hu Heng-Kai  , Wang Kai  , Yang Guang  , Liu Qian  , Pei Wen-Jiang  , Qiu Shen-Wei  , Wei Cheng-Jian  , Zhang Yi-Feng  ,   College of Electronic and Information Engineering, Nanjing University of Technology, Nanjing 210009, China;,   Department of Radio Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

A modified susceptible-infected (SI) model is developed in this paper. The mean field approximation method is further adopted. This present research is based on traffic-driven epidemic spreading behavior. Take MIP routing for example, diffusion coefficient τ, traffic generation rate λ, infection rate β and their relationship with the actual betweenness bk are re-explored under the SI model. Both the theoretical and experimental results indicate that under the same internet topology and routing strategy, the diffusion coefficient τ is inversely proportional to average traffic generation rate λ and infection rate β.
Broadband single-peak filtering characteristics of coated long-period fiber gratings
Authors: Chen Hai-Yun  , Gu Zheng-Tian  , Yang Ying  ,   School of Optical-Electric and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   Laboratory of Opto-Electric Functional Films, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, China;,   Institute of Information Optics, Zhejiang Normal University, Jinhua 321004, China
Published: December 2020

A coated long-period fiber grating (LPFG) operating at the phase-matching turning point couples the fundamental core mode to a higher-order cladding mode, producing a single broad-band whose 3dB-bandwidth is dependent on the difference in dispersion between the core mode and a cladding mode, grating length and central wavelength. The variations of film refractive index and thickness influence the difference in dispersion between the core mode and cladding mode and thus, the bandwidth of loss peak. The central wavelength of loss peak also varies with the changes of film parameters. When the film refractive index is 1.57 and the film thickness is 350 nm, the bandwidth of loss peak reaches 302 nm. The bandwidth can be further improved to 334 nm by reducing the grating length based on the fact that the loss at the central wavelength is guaranteed to be more than 6 dB. A further investigation shows that introducing a π phase shift into a uniform LPFG at a proper position that is away from the grating center can increase the bandwidth to 372 nm and more.
Numerical study of shock-induced phase transformation of cerium under low pressure
Authors: Pan Hao  , Hu Xiao-Mian  , Wu Zi-Hui  , Dai Cheng-Da  , Wu Qiang  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The dynamic responses of cerium under low pressure, including γ →α phase transition, are numerically studied in this paper. The velocity profiles of shock experiments show that the transition process between the two phases is smooth and there is no obvious disconnection between the two plastic waves of the particle velocity profiles. Three important problems in the dynamic response, including constitutive model, Hugoniot relation and phase transition/reversal, are discussed. A multi-phase equation of state and constitutive model of Ce are presented in this paper after analyzing the typical wave configuration of cerium under the shock loading and releasing. The dynamic phase transition model is built for the non-equilibrium course in the phase γ → α transition induced by shock wave. The numerical results accord with the experimental data of the plane impact tests, indicating that the dynamic phase transition model can describe the dynamic response under low pressure of cerium more reasonably.
Non-Gaussian analysis of noise for metal interconnection electromigration
Authors: He Liang  , Du Lei  , Huang Xiao-Jun  , Chen Hua  , Chen Wen-Hao  , Sun Peng  , Han Liang  ,   School of Technical Physics, Xidian University, Xi'an 710071, China
Published: December 2020

Based on scattering theory, the resistance of polycrystalline interconnection originates mainly from vacancies and voids scattering at grain boundary. Through using the free volume concept, the scattering process at grain boundary is simulated, and a non-Gaussian model of noise is establised. The model shows the earlier electromigration noise is gaussian, through electromigration process, noise turns non-Gaussian, which reflects the change of dynamic mechanism. Bicoherence coefficient is used to characterize the non-Gaussian noise. Finally, experimental result validates the model.
Stability of organic light-emitting device
Authors: Zhang Xin-Wen  , Hu Qi  ,   Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210046, China
Published: December 2020

Organic light-emitting device (OLED) has well-recognized advantages in simple structure, low-driving voltage, flexibility, large area and availablity. It shows tremendous commercial applications in optical communication, information display and solid-state lighting, and has been one of the most attractive projects in optoelectronic information field over the last decade. Since 1987, OLED has rapidly developed, its brightness and efficiency has reached the practical demands. However, one of the main challenges to the industrialization is the stability of the device. In this paper, some of the extrinsic and intrinsic degradation mechanisms in OLEDs are summarized and discussed, such as the dark-spot formation, morphological instability of organic thin film, metal-atom diffusion, Alq3 cationic and positive charge accumulation. After that, we summarize the approaches to obtaining the long lifetime OLED. Finally, some perspectives on the stability of OLED are proposed.
High frequence structure simulator simulation and performance analysis for nearfield and wide band electric coupling antenna
Authors: Yang Yong  , Sun Wei-Qiang  , Zhuang Qian-Wei  , Feng Tao  , Xu Sheng-Yong  , Xie Si-Shen  ,   School of Electrical Engineering and Computer Science, Peking University, Beijing 100871, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Electric field coupling antenna is a new type of antenna that can be used in high speed wireless communication at a very short distance. It is the working antenna for TransferjetTM technology promoted by Sony Corporation. In this paper, we use the high frequency structure simulator to design a typical antenna of this kind with parametric structures. We analyze the influences of the length (Ls) and width (Ws) of the short stub, the height (H) of coupling electrode on the performance of the antenna corresponding to the centre frequency and bandwidth. We also analyze the effects of the distance (d) and angle () between two antennas and the size of coupling electrode (Lc) on transmission loss. Finally, we design an antenna satisfying the technology standards of TransferjetTM, thus demonstrate its working performance.
Response properties of NbN superconductor nanowire for multi-photon
Authors: Zhou Yu  , Zhang La-Bao  , Jia Tao  , Zhao Qing-Yuan  , Gu Min  , Qiu Jian  , Kang Lin  , Chen Jian  , Wu Pei-Heng  ,   Department of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Published: December 2020

In this paper, we study the response properties of multi-photon of NbN superconductor nanowire in superconducting single photon detector (SSPD). We measure the NbN nanowire device's DC characteristics and detection probability for single and multi-photon light pulse signal at a temperature of 3.5 K. The measured results show that the superconducting transition current of superconductor nanowire decreases as light irradiation intensity increases. The photon number detected by SSPD is derived from the slope of detection probability versus light intensity. We find that the detected photon number increases as superconducting nanowire bias current decreases. Moreover, based on quantum optics and hotspot theory, we analyze the mechanism of the multi-photon response of superconducting nanowire semi-quantitatively. This result may be of benefit to understanding SSPD and developing the SSPD with the capability of resolving photon number.
Study of the stable components in extended-range forecasting for the coming 10-30 days during the snow storm event in November 2009
Authors: Wang Kuo  , Feng Guo-Lin  , Sun Shu-Peng  , Zheng Zhi-Hai  ,   College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

In this paper, we extract stable components in extended-range forecasting for the coming 10-30 days by using empirical orthogonal function analysis and some other methods during the snow storm event in November 2009. At the first time, stable components in extended-range forecasting for the coming 10-30 days can be divided into two parts: climatic stable components and abnormal stable components, by contribution rate analysis, similarity coefficient and so on. We combine climatic stable components and low-pass filter components to obtain climatological background field. The results show as follows. 1) The circulation pattern of climatological background field persists for a long time and changes slowly. It provides climatological background for the weather event mainly. 2) The climatological background field can indicate the fluctuations of semi-permanent or permanent center with a large space scales. The climatological background field cooperates well in vertical divisions. 3) The abnormal stable components reflect abnormal circulation, and the circulation pattern of abnormal stable components corresponds to the snow storm event in November 2009 well on the time scale. The climatological background field represents circulation pattern background and the abnormal stable components represent the relative strength of weather system.
The preliminary research about the precursory signals of abrupt climate change based on critical slowing down phenomenon
Authors: Wu Hao  , Hou Wei  , Yan Peng-Cheng  , Feng Guo-Lin  ,   College of Physical Science and Technology, Yangzhou University, Yangzhou 225002, China;,   National Climate Center, Beijing 100081, China;,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

In recent years, critical slowing down phenomenon has shown great potentials in the area of disclosing whether complex dynamic system tends to critical cataclysm. Based on the concepts of critical slowing down, the observed data of pacific decadal oscillation (PDO) index and the national average monthly temperature are processed in this article to study the precursory signals of abrupt climate change. Take the abrupt climate change in a period from the late1970s to the early 1980s for example, the variances and autocorrelation coefficients which can characterize critical slowing down are calculated separately. The results show that the PDO index and the national average monthly temperature both have obviously a critical slowing down phenomenon before the abrupt climate change takes place, which indicates that critical slowing down phenomenon is a possible early warning signal for abrupt climate change. The introduction of critical slowing down theory into abrupt climate change precursory signals and study on it have practical significance and important scientific value for thoroughly understanding the abrupt climate change and for catching the precursory signals of abrupt climate change.
Integral-form solution of the Caldeira-Leggett density operator equation obtained by virtue of thermo entangled state representation
Authors: Ye Qian  , Chen Qian-Fan  , Fan Hong-Yi  ,   Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Open quantum system, namely system-reservoir model, is described by a master equation of density operator. For example, the Caldeira-Leggett eqaution describes dissipative phenomenon of solid physics. Although some efforts have been made to derive the exact expression of this master equation, so far as we know, it has not been reported in the literature. The purpose of this paper is to provide a new approach to solving the Caldeira-Leggett equation, via this approach the explicit integral-form expression of ρ(t) can be obtained. The main point of this approach is to convert equation of density operator into an equation of density state vector, and then project density state vector into thermo entangled state representation and convert it into wave function by using the technique of integration within an ordered product of operators. Thus the master equation for Caldeira-Leggett model is converted into an differential equation of wave function. Wave function is also a function. The wave function can be obtained via the approach to solving the differential equation in mathematics. It can be converted into a density state vector and density operator. Using the technique of integration within an ordered product of operators again, the integra-form solution of the Caldeira-Leggett equation is obtained.
Theoretical study on electron-impact excitation processes and the relevant polarization of radiation of 2s1/2—2p3/2 in W65+ through W71+
Authors: Ma Xiao-Yun  , Dong Chen-Zhong  , Wu Zhong-Wen  , Jiang Jun  , Xie Lu-You  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

In this paper, the excitation energy and radiative transition probabilities are calculated for 2p3/2-2s1/2 transition in W65+ through W71+ ions, by using GRASP92 package based on the multi-configuration Dirac-Fock method. The present calculations are compared with other theoretical and experimental results [Podpaly et al. 2009 Phys. Rev. A 80 052504], and they are in good agreement each other. Furthermore, the total cross section and the magnetic sublevels cross section for the 2s1/2-2p3/2 excitation in W65+ through W71+ ions as well as the polarization of resulting transitional lines are calculated, with a fully relativistic distorted-wave method. Based on the calculation, the variations of the excitation cross sections and polarization with the increase of incident electron energy are discussed systematically.
Multi-bottle beam generated by vaulted axicon
Authors: Cheng Zhi-Ming  , Wu Feng-Tie  , Fang Xiang  , Fan Dan-Dan  , Zhu Jian-Qiang  ,   College of Information Science and Engineering, Huaqiao University, Quanzhou 362021, China;,   Shanghai Institute of Optics and Fine Mchanics, Chinese Academy of Sciences, Shanghai 29800, China
Published: December 2020

A novel optical element, vaulted axicon, is proposed for the first time in this paper. We analyze the distribution of light field with diffraction theory, and simulate the intensity distribution behind vaulted axicon. The result shows that multi-bottle beam can be obtained after a plane wave has passed through an vaulted axicon, moreover the intensity of the bottle beam is very high in the focal region because of the energy of spherical wave is significant concentrated in this region. The simulation and comparison show that the intensity around the bottle beam generated by vaulted axicon is far higher than that generated by superposition of two Bessel beams, therefore the particle trapping efficiency can be significantly increased. By comparing the scattering forces of bottle beam generated by the two methods, we demonstrate that the bottle beam generated by vaulted axicon is superior in particle trapping.
The effects of proton implant energy on threshold and output power of vertical cavity surface emitting laser
Authors: Mao Ming-Ming  , Xu Chen  , Wei Si-Min  , Xie Yi-Yang  , Liu Jiu-Cheng  , Xu Kun  ,   Key Laboratory of Optoelectronics Technology Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

A method of balancing the output power and threshold current property of vertical cavity surface emitting laser is studied. The relationship between proton implantation energy and device performance is analyzed by simulation and experiment. It is found that a higher injection energy can destroy the active region, thus reducing the output power property. The threshold current will be increased since a lower injection energy may weaken the restriction on the injection current. The results indicate that 315 keV injection energy is the right choice for our device structure. The output power and threshold current obtained under 10 μm aperture are 1.7 mW and 4.3 mW, respectively.
Wavelength-tunable linear-cavity passively mode-locked Yb-doped fiber laser based on volume Bragg grating
Authors: Bai Yang-Bo  , Xiang Wang-Hua  , Zu Peng  , Zhang Gui-Zhong  ,   College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronics Information and Technical of Ministry of Education, Tianjin University, Tianjin 300072, China
Published: December 2020

The linear-cavity all-normal-dispersion Yb-doped fiber laser based on semiconductor saturable absorber mirror and reflection type volume Bragg grating (VBG) is demonstrated. A passively mode-locked pulse stable output with a 0.32 nm spectral bandwidth, a 10.2 mW maximum average output power, a single pulse energy of 0.63 nJ and a 16.42 MHz repetition rate is achieved, when the central wavelength of pulse is 1030 nm. The central wavelength of the pulse can be tuned approximately from 1011.9 nm to 1050.6 nm by the spectral separation and mode selection effect of VBG with a tuning range of 38.7 nm at room temperature. Q-switched, second harmonic mode-locked, simultaneous dual wavelength and triple wavelength output are observed. This mode-locked fiber laser can be used as the optical source in wave division multiplexing optical time division multiplexing communication system and optical source of optical coherence tomography due to its tunable wavelength.
Acoustic scattering from a finite periodically bulkheads in cylindrical shell
Authors: Pan An  , Fan Jun  , Zhuo Lin-Kai  ,   State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Acoustic scattering from a submerged finite cylindrical shell with periodically bulkheads, insonified by an incident plane wave, is studied. The motion of shell is described by Donnell equations, while the motion of bulkheads is described by thin plate motion equations and plane stress equations with considering axial force circumferential force radial force and bending moment simultaneously. Through angle-frequency spectrum besides the surface elastic waves, Bragg waves and Bloch-Floquet waves for the periodically bulkheads, the interactions between bulkheads resonance can be seen. Finally the theory is verified by experiment. Bragg waves, partial Bloch-Floquet waves and resonance of bulkheads highlight are all accordant with theory.
Properties of sound waves in granular matter analyzed by an elastic potential model
Authors: Zheng He-Peng  , Jiang Yi-Min  , Peng Zheng  , Fu Li-Ping  ,   School of Physics and Electronics, Central South University, Changsha 410083, China
Published: December 2020

According to the point of view that static dense granular matter is a nonlinear elastic body, we derive an analytic sound speed expression given by its elastic potential, for the case of samples with cylindrical symmetry and sound waves propagating in the directions along and perpendicular to the symmetry axis. By a detailed comparison of the expressions with experiments reported in the literature, we conclude that the acoustic method can determine all material parameters appearing in the elastic potential accurately, which provides us with an important way of studying detailed nonlinear elasticity behaviors of granular materials, if stresses, density, and their uniformity of samples are thoroughly controlled and measured.
Effects of magneic field and quantum dot size on properties of exciton
Authors: Shen Man  , Zhang Liang  , Liu Jian-Jun  ,   College of Physical Science and Information Engineering, Hebei Normal University, Shijiazhuang 050024, China;,   Department of Application Information Technology, Hebei Normal University, Shijiazhuang 050024, China;,   Physics Department, Shijiazhuang University, Shijiazhuang 050035, China
Published: December 2020

In In0.6Ga0.4As/GaAs quantum dot, using a one-dimensional effective potential model and the finite difference method, we theoretically study the properties of an exciton under the influence of an applied magnetic field, such as the transition energy, the binding energy, the spatial distributions of the electron and the hole. The effects due to the applied magnetic filed and the quantum confinement on the binding energy are analyzed, and the following results are obtained: the ground state transition energy of the heavy-hole exciton can split into four energy levels due to the Zeeman effect, of which the results are in good agreement with experimental results; the binding energy increases monotonically with the increase of lateral confinement or magnetic field; the size of the quantum dot has a significant influence on the binding energy of the exciton, which can be seen both from the average distance between the electron and the hole and from the wave function distributions of the exciton.
Research on reduction of parasitic absorption caused by surface plasmon polariton
Authors: Huang Qian  , Zhang De-Kun  , Xiong Shao-Zhen  , Zhao Ying  , Zhang Xiao-Dan  ,   Institute of Photo-Electronics Thin Film Devices and Technique of Nankai University, Key Laboratory of Opto-Electronic Information Science and Technology (Nankai University, Tianjin University), Ministry of Education, Key Laboratory of Photo-Electronics Thin Film Devices and Technique of Tianjin, Tianjin 300071, China
Published: December 2020

In this article, we investigate the optical and electrical properties of surface plasmon polariton of Ag nanoparticles influenced by surrounding medium with different conductivities. Ultraviolet-visible infrared spectra and surface enhanced Raman scattering show that when the Al2O3 films are used as a surrounding medium, the optical loss caused by surface plasmon polariton of Ag nanoparticles will be reduced and the surface electromagnetic (EM) field will be enhanced, while conductive substrate may lead to the surface plasmons transmitting along the substrate layer then reduce the EM field and enhance the optical absorption. This property provides an effective approach to the use of optical and electrical properties of surface plasmon polariton in thin film solar cells when a thin film of Al2O3 is added as a cover layer.
Two-dimensional hole gas in p-GaN/p-AlxGa1-xN heterojunctions and its influence on Ohmic contact
Authors: Wang Xiao-Yong  , Chong Ming  , Zhao De-Gang  , Su Yan-Mei  ,   Institute of Semiconductors, Chinese Academy of Sciences, Nano-Optoelectronics Laboratory, Beijing 100083, China;,   Institute of Semiconductors, Chinese Academy of Sciences, State Key Laboratory of Integrated Optoelectronics, Beijing 100083, China
Published: December 2020

In this paper, the characteristics of the two-dimensional hole gas (2DHG) in p-GaN/p-AlxGa1-xN heterojunction is investigated in detail, based on self-consistent solutions of one-dimensional Poisson and Schrdinger equations. The valence band structures and the 2DHG distributions are calculated in the cases of different Al components and piezoelectric polarization effects. Then, the influences of Al components and piezoelectric polarization effects on 2DHG are analysed specifically. The results show that with the increase of Al component, the quantum well at the heterojunction interface turns deeper and narrower, which leads to an accelerated growth of the 2DHG peak density and a line increase of the 2DHG sheet concentration. Furthermore, piezoelectric polarization effects also make the quantum well at the heterojunction interface deeper and narrower, at the same time, the Fermi level moves close to the top of the barrier and the location of peak density moves close to the heterojunction interface. In addition, the influences of valence band offset and acceptor doping concentration on 2DHG are relatively small. Ohmic contact of p-AlxGa1-xN is fabricatea with the 2DHG, and its I-V characteristic is much better than that without the 2DHG, which indicates that the 2DHG can significantly improve the performance of p-AlxGa1-xN ohmic contact.
Preparation and luminescence properties of a red phosphor Mg5SnB2O10:Eu3+, Bi3+ for light emitting diode
Authors: Wang Qian  , Ci Zhi-Peng  , Wang Yu-Hua  , Zhu Ge  , Wen Yan  , Liu Bi-Tao  , Que Mei-Dan  ,   School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
Published: December 2020

A novel Mg5SnB2O10: Eu3+, Bi3+ red phosphor is synthesized by a solid-state reaction, whose structure and photoluminescence properties are investigated through X-ray diffraction, diffuse reflection spectrum and photoluminescence spectrum. The excitation spectrum centred at 393 nm reveals the 7F0-5L6 characteristic transition of Eu3+, which matches well with the near ultraviolet chip for light emitting diode (LED). In the emission spectrum under 393 nm excitation, peaks at 591, 612 and 701 nm could be attributed to the transitions of 5D0-7F1, 5D0-7F2 and 5D0-7F4 of Eu3+, respectively. With the introduction of Bi, the emission intensity is improved due to the energy transfer from Bi3+ to Eu3+. In this paper, the optimal doping concentration of Eu3+ and Bi3+ is determined to study the photoluminescence properties and the optimal sample Mg4.89Eu0.1Bi0.01SnB2O10 is obtained. The integral intensity of the emission spectrum for Mg4.89Eu0.1Bi0.01SnB2O10 phosphor excited at 393 nm is about 1.1 times stronger than that of Y2O2S: Eu3+ excited at 394 nm.
Growth evolution of Ge quantum dot modulated by the atom bombardment during ion beam sputtering deposition
Authors: Xiong Fei  , Yang Jie  , Zhang Hui  , Chen Gang  , Yang Pei-Zhi  ,   Research Institute of Engineering and Technology, Yunnan University, Kunming 650091, China;,   Institute of Advanced Materials for Photo-Electronics, Kunming University of Science and Technology, Kunming 650093, China;,   Key Laboratory of Education Ministry for Advance Technique and Preparation of Renewable Energy Materials, Yunnan Normal University, Kunming 650092, China
Published: December 2020

The Ge quantum dots on Si substrate are prepared by ion beam sputtering deposition (IBSD). The growth evolution is observed to experience two stages with Ge coverage (θ) increasing. When θ increases from 6 monolayers (ML) to 10.5 ML, the average base width and height of quantum dots both increase, and the dome shape dots with small aspect ratio values are obtained. As the dots grow up, Ge atoms are also accumulated in the wetting layer, which contributes to the observed quantum dot density increasing mildly during this stage. When θ is in a range from 11.5 ML to 17 ML, vertical growth dominates the dot evolution. Another dome shape quantum dots are prepared with large aspect ratio values. Ge coverage gain results in the dot density increasing rapidly. A wetting layer decomposition process is demonstrated to give significant effect on that. The growth transition occurs as θ increases from 10.5 ML to 11.5 ML, and the dot density is enhanced 6.4 times in this course. So it is concluded that the evolution of Ge quantum dot prepared by IBSD is very different from that deposited on the thermal equilibrium condition. The observed characters of the dot shape and size distribution result from the kinetic behaviors of the surface atoms which are restricted by the thermodynamic limitation. Ge coverage is the one of the most important factors which can change the free energy. On the other hand, the energic sputtered atom bombardment enhances surface diffusion and defers nucleation of three-dimensional islands until the superstrain wetting layer is formed, which can also change the system free energy and the surface atom kinetic behaviors. So the growth evolution of Ge quantum dots prepared by IBSD is related so much with the effect of atom bombardment on the quantum dot growth.
The influence of modified electrodes by V2O5 film on the performance of ambipolar organic field-effect transistors based on C60/Pentacene
Authors: Zhao Geng  , Cheng Xiao-Man  , Tian Hai-Jun  , Du Bo-Qun  , Liang Xiao-Yu  , Wu Feng  ,   School of Science, Tianjin University of Technology, Tianjin 300384, China;,   Institute of Material Physics, Tianjin University of Technology, Key Laboratory of Display Material and Photoelectric Devices, Ministry of Education, Tianjin Key Laboratory of Photoelectric Materials and Device, Tianjin 300384, China
Published: December 2020

C60/Pentacene-based ambipolar organic heterostructure field-effect transistors (AOFETs) with Al source-drain (S/D) electrodes modified by inserting a transition metal oxide (V2O5) layer are fabricated. Compared with the device without V2O5 modified layer, the modified device shows good ambipolar characteristics with a hole mobility of 8.6× 10-2 cm2/V·s-1 and an electron mobility of 6.4× 10-2 cm2/V·s-1, and threshold voltages of 25 and -25 V, respectively. These performance improvements are ascribed to the presence of V2O5 layer at the Pentacene/Al interface which significantly reduces the source/drain contact resistance, increases the holes injection and makes electronic and hole injection close to balance. This result indicates that modified electrodes by V2O5 film is an effective approach to fabricating low cost and high performance AOFETs for realizing commercial applications.
A study on the mechanism of RecA in homologous recognition by using single molecule fluorescence tracking
Authors: Pang Zhe  , Wang Shuang  , Li Hui  , Xu Chun-Hua  , Li Ming  ,   Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

RecA plays an important role in homologous recognition in prokaryotes, and it has become a hot point in homologous recognition related research since its discovery. We establish an assay by combining total internal reflection fluorescence and flow stretching to visualize in real time the motion of single RecA-ssDNA filaments which are tagged with fluorescent beads. This enables us to study the interaction of RecA-ssDNA filaments with their templates in the homologous recognition process. It is found that the searching and binding is a short-time (τ=0.2 s) and short-distance (l=1.05 μm) process. Two distinguished motion modes for the RecA-ssDNA filament are observed, a Brownian motion and a directed motion. The observations suggest a model that a RecA-ssDNA filament just interacts weakly with the template DNA before it binds firmly to the template DNA. If no homologous site is found in a searching process, the filament drops off the template and repeats the searching process again until it finally finds its target.
Coherent X-ray diffraction imaging and its applications in materials science and biology
Authors: Fan Jia-Dong  , Jiang Huai-Dong  ,   State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
Published: December 2020

In site quantitative, high-contrast and high-resolution imaging of micro/nanoscale material is an important goal of the X-ray microscopy and imaging. A novel method which is called lensless imaging or coherent X-ray diffraction imaging, is a promising approach to solving these problems. In this review, a brief introduction to imaging theory and development of coherent X-ray diffraction imaging, and some typical applications in material science and biology are presented. For instance, two-dimensional (2D) imaging of Bi dopant distribution in a Si crystal, quantitative three-dimensional (3D) imaging of a GaN quantum dot with core shell structure, 2D imaging of stained Escherichia coli bacteria, nanoscale imaging and mechanisms of biomineralization of fish bones, 2D high-contrast imaging of an unstained herpes virus, 3D high-resolution imaging of an unstained yeast cell and in situ quantitative analysis are illuminated. Finally, the future prospect of coherent X-ray diffraction imaging is given. With the development of X-ray free electron lasers and combining cryogenic techniques with coherent X-ray diffraction microscopy, coherent diffraction imaging will be a powerful tool and widely used in materials science and biology.
Generation of correlated pseudorandom variables in Monte Carlo simulation
Authors: Wen De-Zhi  , Zhuo Ren-Hong  , Ding Da-Jie  , Zheng Hui  , Cheng Jing  , Li Zheng-Hong  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Correlated pseudorandom variables with prescribed marginal distribution functions sometimes are required in simulation such as in Monte Carlo studies. In this paper, we present a general procedure and a simple but effective numerical approach to generating correlated random variables sampling sequence with prescribed marginal probability distribution functions and correlation coefficient matrix based on linear transformation-nonlinear transformation with Choesky factor. Some simulation results are reported. Simulation results show that the collections of random numbers generated by the presented procedure have desired correlations and pass the Kolmogorov-Smirnov non-parametric hypothesis test of specified marginal distribution. Some restrictions on the application of this method are discussed.
Routing protocol for wireless ad hoc quantum communication network based on quantum teleportation
Authors: Yu Xu-Tao  , Xu Jin  , Zhang Zai-Chen  ,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China;,   Department of Physics, Southeast University, Nanjing 210096, China;,   State Key Laboratory of Mobile Communications, Southeast University, Nanjing 210096, China
Published: December 2020

A concept of wireless ad hoc quantum communication network is proposed and a routing protocol is designed for wireless quantum communicaiton network with complex structure. The routing protocol is on-demand and the routing metric is based on the number of entangled particle pairs. The node that wants to send information carried by quantum state can initiate a route request and establishment procedure. The destination node chooses path by the routing metric and sends route reply message along the selected path. During the information transmission, if the quantum channel or the wirless channel between any neighbors in the selected path is broken, a route discovery process is reinitiated to set up a new route. Nodes in the selected path use a both-end approximation algorithm to establish a quantum channel. After the quantum channel is established, the quantum state is transferred by quantum teleportation and the information transfer between any two nodes in wireless ad hoc quantum communication network is finished.
Active adaptive fuzzy integral sliding mode control for unified chaotic system with uncertainties and disturbance
Authors: Lu Yong-Kun  ,   School of Electronic Information and Automation, Tianjin University of Science and Technology, Tianjin 300222, China
Published: December 2020

An active adaptive fuzzy integral sliding mode controller is proposed for a unified chaotic system with parametric uncertainties under external perturbation. An improved control method is designed to guarantee the stability, while maintaining the transient performances of the original nonlinear integral sliding mode control. The proposed method reduces the effects of both the uncontrollable state of unified chaotic system and approximation error of adaptive fuzzy compensator on system state error. The stability of the controller is analyzed by Lyapunov stability theorem. The simulation results show that the system states can be controlled to target points with parametric uncertainties under external perturbation. The effectiveness of this method is illustrated by the numerical simulation.
Error synthesis and statistical analysis on stepped mirror array by Monte Carlo method
Authors: Lü Jin-Guang  , Liang Jing-Qiu  , Liang Zhong-Zhu  ,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun130033, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

To achieve the miniaturization and the static state of the Fourier transform spectrometer, two stepped mirror arrays are introduced into the time-modulation Fourier transform spectrometer to replace of the plane mirrors. The two stepped mirrors can sample the interferogram data in two-dimensional space, which can reduce the size of the instrument and increase the stability of the system. Due to the precision restriction on the stepped mirrors in the fabrication process, the various sub-mirrors of the stepped mirrors may contain various thickness errors and angle errors, which can affect the distribution of the interferogram and the quality of the spectrum. We regard the thickness error and the angle error of all the sub-mirrors as random variables, and synthesize all the error terms into a Fourier transform integration function using Monte Carlo method. By means of statistic analysis on the spectrum error factor, we can appraise the recovered spectrum affected by the thickness error and the angle error of the sub-mirror. The statistical result indicates that the statistical mean of the spectrum error factor increases with thickness standard deviation and angle standard deviation increasing. According to the statistical analysis on spectrum error factor, the tolerances of the thickness standard deviation and the angle standard deviation of the sub-mirror can be determined in the fabrication process of the stepped mirrors.