bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles calculations of the electron transport through Si4 cluster
Authors: Liu Fu-Ti  , Cheng Yan  , Yang Fu-Bin  , Cheng Xiao-Hong  , Chen Xiang-Rong  ,   College of Physics and Electronic Engineering, Yibin University, Yibin 644000, China;,   College of Physical Science and Technology, Sichuan University, Chengdu 610065, China
Published: December 2020

Electron transport properties of Si4 cluster-Au (100) electrode nanojunction is investigated with a combination of density functional theory and non-equilibrium Green's function method. We calculate the geometric structures, electronic structures, conductances, transmission spectra and charge transfers of Au-Si4-Au nanoscale junctions under different distances. We also discuss the variations of conductance and current with external voltage when the distance of junction is 12.004 Å.
Local adaptive H∞ consistency of delayed complex networks with noise
Authors: Tu Li-Lan  , Liu Hong-Fang  , Yu Le  ,   Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430065, China
Published: December 2020

The local adaptive H∞ consistency is intensively investigated for delayed complex dynamical networks with noise. The network under consideration contains unknown but bounded nonlinear coupling functions and time-varying delays which appear in the coupling term and the node system simultaneously. Based on the Lyapunov stability theory, linear matrix inequality optimization technique and adaptive control, several local adaptive H∞ consistency schemes are established which guarantee robust asymptotically consistency for each node of noise-perturbed network as well as achieving a prescribed robust H∞ performance level. Finally, detailed and satisfactory numerical simulations validate the feasibility and the correctness of the proposed techniques.
1/f noise characterization gamma irradiation of GaN-based blue light-emitting diode
Authors: Liu Yu-An  , Zhuang Yi-Qi  , Du Lei  , Su Ya-Hui  ,   School of Microelectronics, Xidian University, Xi'an 710071, China;,   School of Technical Physics, Xidian University, Xi'an 710071, China
Published: December 2020

The electrical model that ionizing radiation reduces the effective power output of GaN-based blue light-emitting diode is proposed by investigating the light/dark current generation mechanism in active region of GaN-based blue light emitting diode device under ionizing irradiation. The model that the ionizing radiation increases the 1/f noise of GaN-based blue light-emitting diode device is proposed by studying the 1/f noise mechanism of the active region of GaN-based blue light-emitting diode device under exposure to ionizing radiation. In the small injection region (I1 A)， the space charge region and the recombination current increase with irradiation dose increasing. Meanwhile, with the increase of the ionizing-irradiation-generated defects, the 1/f noise amplitude increases. In the large injection region (I1 mA), due to the dominant influence of the series resistance, the surface recombination velocity and current increases with irradiation dose increasing. Meanwhile, with the increase of ionizing-irradiation- generated defects, the 1/f noise amplitude increases. The I-V and 1/f noise test results before and after irradiation are in good agreement with theoretical results. In the middle injection region (1 A I 510-5 A), due to the competition between mobility fluctuation caused by energetic carrier scattering and the carrier number fluctuation caused by the newly irradiation-generated defects, as the radiation dose increases, 1/f noise has no significant changes in the frequency domain. However, through the 1/f noise time domain multiscale entropy complexity analysis, a conclusion can be drawn that with the increase of radiation dose, the 1/f noise domain multi-scale entropy becomes more complex. 1/f noise amplitude ultimately proves to be sensitive to reflect the reliability of GaN-based blue light-emitting diode ionizing irradiation in the case of small injection and large injection. The greater the noise amplitude, the higher the irradiation induction trap is, and the greater the generation-recombination current related to the dark current, the smaller the photocurrent related to the diffusion current is, so that the luminous efficiency of the device, the optical output power, and other performance parameters decrease, thus affecting the reliability of the device and resulting in the more failure devices. 1/f noise time domain multiscale entropy complexity can reflecte ionizing irradiation reliability of GaN-based blue light emitting diodes sensitively in the middle injection region.The more the multiscale entropy complexity, the bigger the irradiation induction generation-recombination current is, and the worse the reliability of the device is. The present study provides a method of characterizing the GaN-based blue light-emitting diode ionizing irradiation reliability according to 1/f noise.
Characterization of elastic properties of a sample by atomic force microscope higher harmonic amplitude
Authors: Zhang Wei-Ran  , Li Ying-Zi  , Wang Xi  , Wang Wei  , Qian Jian-Qiang  ,   Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Department of Applied Physics, Beihang University, Beijing 100191, China
Published: December 2020

When the atomic force microscope cantilever in tapping-mode is vibrated at a frequency close to its fundamental resonance frequency, the tip on its free end will be close to and away from the sample periodically. The higher harmonic signals produced by non-linear interactions between the tip and sample surface contain more nanomechanical information. We study the influence on the contact time by different elastic modulus and the relationship between higher harmonic amplitude and contact time. By theoretical analysis and calculation, we obtain the law of characterizing the sample surface elastic difference with the higher harmonic amplitude. Moreover, we obtain the experimental result consistent with the theory, on our homemade higher harmonic system.
Super-diffraction imaging in three-dimensional localization precision of the double-helix point spread function
Authors: Chen He  , Yu Bin  , Chen Dan-Ni  , Li Heng  , Niu Han-Ben  ,   Optoelectronic Devices and Systems (Ministry of Education/Guangdong) Key Laboratory, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
Published: December 2020

The combination of switch effect and single molecule positioning can realize the sample super diffraction resolution imaging, and double helix point spread function will be a single molecular orientation nanometer resolution extending from two dimensions to three dimensions. In this paper, three-dimensional (3D) positioning accuracy of the double helix point spread function is discussed. First, the theoretical localization accuracy for an unbiased estimator of the double-helix point spread function is compared with that for 3D localization using Fisher information and the influences of localization accuracy including photon number, varying levels of background and pixel size are analyzed. Second, based on the localization algorithm of gaussian fitting, which is usually adopted in data analysis of single molecular orientation in the experimental process, the axial localization accuracy of double helix point spread function is obtained by the error transfer function law. Computer simulation results show that under the condition of more than 1000 photons in number, the positioning accuracy of gaussian fitting localization algorithm and theory localization accuracy of Fisher information are in good agreement. The discussion of the paper provides not only the theoretical basis for 3D positioning accuracy of double helix point spread function, but also the theoretical guidance for the experiment at the same time.
Atom movement in momentum dependent light dipole lattices
Authors: Yu Xue-Cai  , Wang Ping-He  , Zhang Li-Xun  ,   Opto-Eletronic Message College, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Atom movement in light-induced dipole lattices is investigated in this paper. Momentum-dependence of the dipole potential is particularly considered. Momentum squeezed variance and position amplified variance feature are revealed, from which we predict that a single particle state of boson atoms confined in optical lattice will approach to a momentum squeezed line state. The results show also that under red detune, the atom movement experiences three phases. In the first phase, the atom is slowed down gradually in a long period with atom momentum damply oscillating. In the second phase, atom momentum will quickly reduce to hk(Ω/γ)2 with hk momentum of one photon, Ω Rabi frequency, and γ decay constant of atom wave function, as the momentum reduces to the momentum of one photon. Finally, atoms will be confined in the vicinity of wave nodes.
Frequency indistinguishibility investigation of generated coincident-frequency entanglement via ultra-fast pulsed sources
Authors: Zhang Yu  , Quan Run-Ai  , Bai Yun  , Hou Fei-Yan  , Liu Tao  , Zhang Shou-Gang  , Dong Rui-Fang  ,   Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Science, Xian 710600, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The frequency entangled biphoton source generated via spontaneous parametric down-conversion process (SPDC) has found numerous applications in quantum information processing and relevant fields. We report on an experimental generation of coincident-frequency entanglement from periodically poled potassium titanyl phosphate, pumped by an ultra-short pulsed optical source with duration less than 20 fs. Based on the Hong-Ou-Mandel interferometric coincidence measurement setup, a visibility of about 42% is demonstrated, which indicates degraded frequency indistinguishibility of the down-converted biphotons. Through theoretical investigation, such a degradation can be perfectly explained by the nonnegligible second-order dispersion terms in the Taylor-expanded phase mismatching function for the case of ultra-broadband spectrum of the pulsed pump. The fitting to the experimental results is further used and perfect agreement is achieved. The results imply that the spectral bandwidth of the pump can affect the generated coincident-frequency entanglement.
The mechanism of the interference structure in shallow water vector acoustic field and experimental investigation
Authors: Lin Wang-Sheng  , Liang Guo-Long  , Fu Jin  , Zhang Guang-Pu  ,   Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China
Published: December 2020

The microscopic structure characteristic of low frequency sound propagation in shallow water is that a stable space-frequency interference structure represented by waveguide invariant exists. Both the scalar field and the vector field determine all the features of the acoustic field. The vector field characteristics of space-frequency interference structure in shallow water acoustic field are investigated. The theoretical analyses of the mechanism of interference structure in the sound pressure spectrum, the kinetic energy density spectrum, and the acoustic intensity flow spectrum in shallow water vector acoustic field are conducted, the numerical simulation studies of the interference of the Pekeris waveguide in energy and energy flow density characteristics are performed, and the sea trials for broadband sound source radiation vector sound field interference properties and characterization are also carried out. The experimental results accord with the theoretical analyses and simulation results very well. The research results show that stable space-frequency interference structure in acoustic vector field exists in many forms for modal coherent in short-distance and long-distance. In addition to various forms of energy and energy flux density spectra, in coherence-coefficient spectrum there appear the interference characteristics. These forms of space-frequency interference structure can be described by waveguide invariant theory effectively.
Study on bubble dynamics near plate with hole based on boundary element method
Authors: Liu Yun-Long  , Zhang A-Man  , Wang Shi-Ping  , Tian Zhao-Li  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

In this work the bubble dynamics near a plate with circular hole is investigated. Numerical model for bubble dynamics is established based on incompressible potential theory. To overcome the numerical limitation of traditional boundary element method for the case with small initial distance between bubble and the edge of hole, the fluid domain is divided into two semi-infinite domains which are solved separately by fusing the bubble wall and the plate wall together, by which numerical simulation in various parameter ranges is implemented. The numerical results match the experimental ones well. Through the analysis of bubble dynamics near circular hole, we find that the influence of hole is opposite to that of solid wall. During the expansion phase, cavity-attraction effect is exerted on the bubble, while the bubble is pushed away during the collapsing phase. In some specific cases, opposite-jets are formed under the conjunction of solid plate and circular hole. Finally, the case where bubble wall and solid wall are fused together is analyzed to study the bubble dynamics after the separation of fluid domain and the influences of no-dimensional parameters.
A new method of simultaneous focal spot shaping and polarization smoothing using crystal phase plate
Authors: Geng Yuan-Chao  , Liu Lan-Qin  , Wang Wen-Yi  , Zhang Ying  , Huang Wan-Qing  , Su Jing-Qin  , Li Ping  ,   Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

A new method is proposed in which uniaxial crystal is used to fabricate the phase plate, with which shaping and polarization smoothing of the target focal spot can be achieved simultaneously in the laser driver of inertial confinement fusion. The principle of crystal phase plate (PS-CPP) is analyzed using the scalar diffraction theory. The solution of crystal surface shape is obtained from the distribution characteristics of the focal spot. Numerical simulation is developed to analyze the application of PS-CPP. The results show that under the conditions of particular crystal cutting angle and surface shape, PS-CPP can be obviously effective for focal spot shaping and smoothing, and the effectiveness is as good as that of the combination of continuous phase plate and the polarizing smoothing crystal.
Enhancement of emission from ZnO nanobelts via surface plasmons
Authors: Ren Yan-Dong  , Hao Shu-Juan  , Qiu Zhong-Yang  ,   School of Physics and Electrical Information Engineering, Daqing Normal University, Daqing 163712, China
Published: December 2020

ZnO nanobelts are synthesized in high yield by a simple chemical vapor deposition method, at low temperature. And then Au nanoparticles are sputtered on the ZnO nanobelts. The effect on the photoluminescence of Au-ZnO composite nanobelts by surface plasmon is systematically investigated by the scanning electron microscopy, transmission electron microscopy and photoluminescence spectrum. The enhancement ratio by surface plasmon resonance and the almost completely suppressed defect emission for Au-ZnO composite nanobelts are observed, and the emission enhancement ratio η of Au-ZnO composite nanobelts reaches a maximal value of 85-fold. Additionally, the photoluminescence mechanism is proposed in terms of the scattering and absorption by Au nanoparticles, the Purcell enhancement factor, and the Ostwald ripening.
Fano resonance in sliver circular gap embedded with a sliver nanorod
Authors: Luo Song  , Fu Tong  , Zhang Zhong-Yue  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China;,   School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

The transmittance property and steady-state magnetic field distribution of the sliver circular gap embedded with a sliver nanorod are investigated using the finite-difference time-domain method. Since the titled nanorod breaks the symmetric steady-state magnetic field distribution, Fano resonance occurs in the composite system. In addition, the transmittance spectrum depends strongly on the tilting angle and topologic shape of the nanorod. These results would be useful for designing filter for specific usage.
Rectifying behavior and photocarrier injection effect in BaTiO3/p-Si heterostructure
Authors: Yang Shi-Hai  , Jin Ke-Xin  , Wang Jing  , Luo Bing-Cheng  , Chen Chang-Le  ,   Shaanxi Key Laboratory of Condensed Matter Structures and Properties, the Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

A good rectifying behavior is observed in a temperature range from 80 K to 300 K in the BaTiO3/p-Si heterostructure, which is fabricated by a pulse laser deposition. The diffusion voltage (VD) decreases with the increase of temperature. A significant photocarrier injection effect is also observed with light irradiation. The photocarrier injection effect increases with the energy of photon increasing. Meanwhile, R-T curve of the BaTiO3 film indicates that the oxygen-deficient BaTiO3 is an n-type semiconductor.
Characteristics of polarization separation of frequency selective surface by lumped inductors and capacitors
Authors: Wang Xiu-Zhi  , Gao Jin-Song  , Xu Nian-Xi  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of the Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

Based on the circuit resonance theory of the electromagnetic local resonance, a novel frequency selective surface structure with the property of polarization separation is designed by loading the lumped inductors and capacitors to the periodic array with “I” elements. The operation principle of the structure at all polarizations is analyzed by using the equivalent circuit method. And the influences of the polarization, incident angle and parameters of the lumped device on the transmission characteristics of the FSS are simulated and discussed by using the full-wave numerical analysis method. The results indicate that the designed structure has a good property of polarization separation at about 6.37 GHz, the transmission characteristics are stable with the scan angle increasing from 0° to 40° at TE and TM polarization, and by controlling the lumped inductors and capacitors, the transmission characteristics for TM polarization can be regulated independently while the transmission characteristics for TE polarization remain constant. The proposed structure is conductive to the designs of the polarization separator and the polarized wave generator.
Spatial optical soliton pairs in a quantum dot with exciton-biexciton coherence
Authors: Zeng Kuan-Hong  , Wang Deng-Long  , She Yan-Chao  , Zhang Wei-Xi  ,   Department of Physics, Xiangtan University, Xiangtan 411105, China;,   Department of Physics and Electronic Science, Tongren University, Tongren 554300, China
Published: December 2020

Considering the exciton-biexciton coherence, we analytically study the linear absorption and nonlinear propagation properties of the probe and signal field in a semiconductor quantum dot. It is found that in the linear case, in the system takes place an electromagnetically induced transparency phenomenon. Furthermore, we obtain that in the system there occurs one- or two-transparency window, or optical gain, which is controlled by adjusting the coupling control field. For the nonlinear case, the weak probe field, which is induced by a signal field, splits into two parts. When their excited self-Kerr and cross-Kerr nonlinear effects balance the refractive effect of the beam, the system exhibits bright-bright, bright-dark, dark-bright, dark-dark soliton pairs.
Influence of data interpolation on positron emission tomography image tomography reconstruction
Authors: Yang Kun  , Liu Xin-Xin  , Li Xiao-Wei  ,   School of Physics, Hebei University, Baoding 071000, China
Published: December 2020

Positron emission tomography (PET) is the most state-of-the-art clinical examination method in the field of nuclear medicine imaging technology. The PET is one of the best tools for tumor diagnosis and guidance in the clinical treatment. The source data that are obtained by PET, need to be processed into a sinogram form data which can be used for image reconstruction. Parallel beam tomographic reconstruction and fan-beam tomographic reconstruction are two methods of imagetomographic reconstruction, respectively, corresponding to parallel beam data processing and fan beam data processing. The processing of the original data is inevitable to destruct the integrity of original data. Nowadays, the PET is a commonly used method of parallel beam image reconstruction. Parallel beam data processing will change original data by data interpolation operation, and the fan beam data processing avoids data interpolation operation. In this paper, we study the influence of data interpolation on PET image reconstruction by comparing the results obtained by the parallel-beam image reconstruction with those obtained by fan-beam image reconstruction.
Effect of raster scan number on damage resistance of KDP crystal irradiated by ultraviolet pulse laser
Authors: Guo De-Cheng  , Jiang Xiao-Dong  , Huang Jin  , Xiang Xia  , Wang Feng-Rui  , Liu Hong-Jie  , Zhou Xin-Da  , Zu Xiao-Tao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The raster scanning experiments for KDP crystal are carried out in R-on-1 mode at energy density below zero probability damage threshold to investigate the damage resistance capability as a function of pulse number after ultraviolet (UV) laser irradiation by using a tripled Nd:YAG laser. The1-on-1 damage measurements after laser irradiation indicate that the damage resistance of KDP is obviously enhanced and the increment is dependent on scanning number. The optical absorption and photoluminescence spectra show that the evolution of oxygen-vacancy centers in KDP crystal is important to the damage resistance capability. The Raman and infrared spectra show that the polarization distortions of PO4, P–OH and P＝O groups induced by UV laser irradiation also contribute to the changes of damage resistance.
Reducing tag collision in radio frequency identification systems by using a grouped dynamic frame slotted ALOHA algorithm
Authors: Pang Yu  , Peng Qi  , Lin Jin-Zhao  , Zhou Qian-Neng  , Li Guo-Quan  , Wu Wei  ,   College of Opto-Electronics Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China;,   Institute of Electronic Information, Sichuan University, Chengdu 610050, China
Published: December 2020

In a radio frequency identification system, designing a tag anti-collision algorithm with good performance is the key to improving the system throughput. In this paper, we propose a principle of dynamic frame size regulation and a method of tag grouping, and design a novel algorithm called grouped dynamic framed slotted ALOHA (GDFSA) through combining the above, which first estimates the number of unread tags and divides them into groups, then uses dynamic frame slotted ALOHA in each group. The simulation results show that the proposed algorithm can stabilize the throughput rate between 34.6%-36.8% and the time slots increase linearly in the identification procedure. When the tag number is beyond 2000 compared with conventional algorithms, the proposed algorithm can enhance the slot efficiency by 30%, and optimize the throughput rate obviously and save the system resource.
Transport properties of fractional coupled Brownian motors in flash ratchet potential
Authors: Lai Li  , Zhou Xue-Xue  , Ma Hong  , Luo Mao-Kang  ,   College of Mathematics, Sichuan University, Chengdu 610065, China
Published: December 2020

Based on the fractional calculus theory, the transport model of fractional coupled Brownian motors in flashing ratchet potential is established. Using the fractional difference, the numerical solution of the model is obtained, and the directional transport properties at various parameters are investigated. Numerical results show that in fractional ratchet system, the fractional order and spring constant not only affect the transport velocity of the particles, but also reverse the current direction. Moreover, when the fractional order is fixed, the generalized stochastic resonance phenomena are observed in the mean transport velocity as the noise density, spring constant or the depth of the ratchet potential varies.
Analysis of ferromagnetic chaotic circuit with nonlinear potential transformer
Authors: Pang Xia  , Liu Chong-Xin  ,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China; School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049
Published: December 2020

By simplifying a substation, a third-order non-autonomous ferromagnetic circuit with single-phase potential transformer has been obtained. Since the voltage is a sine function, by adding a time dimension to the circuit, it becomes a fourth-order autonomous circuit, and some simulation analysis is carried out on it. Studies show the existence of chaotic dynamical behavior in the circuit system, so that we can draw the conclusion that the excitation characteristic of the core has an important influence on the chaotic dynamical behavior of the circuit.
Mode analysis of 0.14 THz overmoded surface wave oscillator
Authors: Wang Guang-Qiang  , Wang Jian-Guo  , Li Shuang  , Wang Xue-Feng  , Tong Chang-Jiang  , Lu Xi-Cheng  , Guo Wei-Jie  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China;,   School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

Mode analysis of the terahertz wave generated by 0.14 THz overmoded surface wave oscillator (SWO) (overmoded ratio D/ 3) is theoretically accomplished and experimentally validated. At first, longitudinal field-expansion method for mode analysis is established aiming at overmoded Cherenkov devices. Then this method is used to analyze the theoretical mode content of 0.14 THz SWO in detail based on the simulation results of electric field extracted from a 2.5-dimensional PIC (particle-in-cell) code. Results show that the mode content of terahertz wave in different characteristic regions of the oscillator is varied due to the mode conversion, and it is dominated by TM02 and TM03 modes accompanied by a small quantity of TM04 mode at the output. Finally, the energy distribution in the near-field radiation of 0.14 THz SWO is obtained by image-displaying method. The experimental result is reasonably in accord with the theoretical distribution calculated from the mode analysis results under experimental conditions, testifying the feasibility of longitudinal field-expansion method for the mode analysis and the correctness of its results.
Effect of oxygen vacancies on the fluorescence and phosphorescence properties of Ca5MgSi3O12：Eu2+, Dy3+
Authors: Gong Yu  , Chen Bai-Hua  , Xiong Liang-Ping  , Gu Mei  , Xiong Jie  , Gao Xiao-Ling  , Luo Yang-Ming  , Hu Sheng  , Wang Yu-Hua  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China;,   Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Ca5MgSi3O12:Eu2+, Dy3+ was synthesized by solid-state reaction. The luminescence center related to the oxygen vacancies existed in the host matrix. Comparing the fluorescence and phosphorescence properties of samples synthesized under different air condiction, we find that the oxygen vacancies played an important role in the fluorescence and phosphorescence properties. Oxygen vacancies can transfer its energy to the luminescence center. Thermoluminescence spectra were used to characterize the effect of oxygen vacancies on the phosphorescence properties. Ca5MgSi3O12:Eu2+,Dy3+ has a great potential to become a promising candidate to be used as long-lasting phosphors.
Generation of the controllable triple-well optical trap by liquid-crystal spatial light modulator
Authors: Zhou Qiao-Qiao  , Xu Shu-Wu  , Lu Jun-Fa  , Zhou Qi  , Ji Xian-Ming  , Yin Jian-Ping  ,   School of Science, Nantong University, Nantong 226007, China;,   State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China;,   School of Science, East China Institute of Technology, Fuzhou 344000, China
Published: December 2020

A new scheme of generating the controllable triple-well optical trap is proposed, in which a liquid-crystal spatial light modulator (SLM) is used to fabricate the phase-type blazed grating and be illuminated with coherent monochromatic light. Three optical wells, each of which has the same intensity distribution, can be formed with relative position of the distribution of an equilateral triangle. The relative positions of the optical wells can be changed by simply and conveniently adjusting the phase distribution of the SLM to realize the evolution and reverse evolution from triple or dual wells to single well. The phase grating is designed by simulation according to the technical parameters of the SLM, and illuminated by the laser with ordinary power. The intensity distributions and intensity changes in the adjustment process for the triple wells are calculated. Results show that the controllable triple-well optical trap with very high peak value of intensity and intensity gradient can be obtained. It has many important applications in the experimental study of atomic and molecular optics.
Positive-negative nonlocal lensless imaging based on statistical optics
Authors: Yao Yin-Ping  , Wan Ren-Gang  , Xue Yu-Lang  , Zhang Shi-Wei  , Zhang Tong-Yi  ,   State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on correlated imaging with pseudo-thermal light, Wu and Meyers independently experimentally showed that both positive and negative images can be obtained by using a novel algorithm. With the theory of statistical optics, we construct the model of thermal light, and demonstrate the novel algorithm for image reconstruction. To deal with the data attained in the correlated imaging, we reorder the intensity recorded by the bucket detector according to the value of fluctuation. For a given fluctuation range with all the records above or below a specific value, we can obtain either positive or negative images by calculate the correlation between the selected records of the bucket detector and the reference detector. Nevertheless, without correlated calculations, positive or negative images can be also produced by directly averaging the corresponding records of the reference detector with positive or negative fluctuations. Meanwhile, the visibility of imaging is greatly enhanced. This correspondence imaging method further demonstrates the importance of intensity fluctuations in the nonlocal imaging with thermal light. We also experimentally show the images that obtained by the correlation method and the positive-negative correspondence imaging method, respectively. Our results indicate that this novel algorithm has a better visibility than that of the conventional correlated imaging.
Low-frequency acoustic absorption mechanism of a viscoelastic layer with resonant cylindrical scatterers
Authors: Yang Hai-Bin  , Li Yue  , Zhao Hong-Gang  , Wen Ji-Hong  , Wen Xi-Sen  ,   Vibration and Acoustics Research Group, Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronics and Automation, National University of Defense Technology, Changsha 410073, China
Published: December 2020

This paper investigates low-frequency acoustic absorption mechanism of a viscoelastic layer with resonant cylindrical scatterers. The viscoelastic layer is 20 mm-thick, and the cylindrical scatterer is a cylindrical cavity coated with a soft rubber layer, with axis in the lateral layer direction. The absorption properties of the viscoelastic layer under the steel-backing condition are studied using the layer-multiple scattering method. Results show excellent absorption performance in the frequency region of 1000–3000 Hz. The absorption mechanism is investigated by analyzing the absorption cross-section of a single scatterer and the multiple scattering of a periodic array of scatterers, together with the displacement field and power dissipation density. Effects of the resonant absorption of a single scatterer and the coupling resonance between the absorption layer and the steel-backing are revealed.
Lagrangian dynamics and seismic wave align of elastic medium
Authors: Fang Gang  , Zhang Bin  ,   School of Geosciences in China University of Petroleum, Qingdao 266580, China;,   School of Science in China University of Petroleum, Qingdao 266580, China
Published: December 2020

In seismic exploration, propagation of seismic wave in earth medium is very complex. Theory of analytical mechanics has advantages for solving complicated problems. In this paper, with the hypothesis of viewing geological medium as an elastic medium, the Lagrange equations of analytical dynamics are built for homogeneous and inhomogeneous earth media. Then the seismic wave equations of elastic medium are obtained from the Lagrange equations. The results provide the basis to study propagation of seismic wave in earth medium and discuss problems related to seismic exploration using Lagrange analytic dynamics.
DFT research on the IR spectrum of glycine tryptophan oligopeptides chain
Authors: Li Xin  , Yang Meng-Shi  , Ye Zhi-Peng  , Chen Liang  , Xu Can  , Chu Xiu-Xiang  ,   School of Engineering, Zhejiang A&F University, Linan 311300, China;,   School of Science, Zhejiang A&F University, Linan 311300, China;,   Key Lab for Magnetism and Magnetic Materials, Ministry of Education, Lanzhou University, Lanzhou 730000, China
Published: December 2020

By using the density functional theory, six structures of oligopeptides chain configuration, consisting of glycine and tryptophan alternatively, are optimized at the B3LYP/6-31 G(d) level. The average binding energy and IR spectrum are calculated. Results show that the stability of oligopeptides grows monotonously with the peptide chain growth. The vibration infrared spectrum analysis show that with the growth of oligopeptides peptide chain, the vibration frequency of one functional group shows blue shift or even-odd shift; while coupling vibration of the same functional group shows red shift, and steady frequencies at the end of chain appear on the infrared spectrum, that is to say, coupling effect, parity effect and size effect exist when, glycine tryptophan oligopeptides, consisting of glycine and tryptophan alternatively, change with peptide chain. The result is significant in measuring the length and number of residue of peptide chain.
A simple and efficient method for preparing silicon nanopit arrays
Authors: Dai Long-Gui  , Xuan Ming-Dong  , Ding Peng  , Jia Hai-Qiang  , Zhou Jun-Ming  , Chen Hong  ,   Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condense Matter Physics，Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

This article presents a simple and efficient method for preparing silicon nanopit arrays structure using laser interference lithography (LIL). Highly ordered nanopit arrays in two dimensions were fabricated on 2 inch Si (001) substrate by LIL and in combination with dry etching and wet etching processes. Dot arrays were directly etched to nanopit arrays with this method, which omitted the necessary steps of metal deposition and lift off in pattern reversal process. Forming a fluorocarbon organic polymer layer on silicon surface after dry etching, which can be used as a wet etching mask, and producing a thin silicon mesa layer under the SiO2 dot arrays by slight over-etching in dry etching process, are two key steps for this method. SEM images show the uniform and controllable pit arrays were prepared; the period of the arrays is 450 nm, the length of the pit is 200280 nm. The pit arrays are composes of square and inverted pyramids, and the four facets of the inverted pyramid correspond to four crystal planes (111) of Si substrate.
First-principle study on the effect of high Ga doping on the optical band gap and the band-edge of optical absorption of ZnO
Authors: Hou Qing-Yu  , Dong Hong-Ying  , Ma Wen  , Zhao Chun-Wang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China;,   Schooe of Chemistry Engineering, Hohhot 010051, China;,   aterial Science, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

Based on the density functional theory (DFT), and using the first-principles plane-wave ultrasoft pseudopotential method, we set up models for a pure ZnO and four different concentrations of Ga-doped ZnO, and the geomertry optimization for the four modes was carried out. The total density of states (TDOS), the band structures (BS) and absorption spectrum were also calculated. Results show that the range of Ga doping amount is limited to 2.08 at% to 6.25 at% in this paper; when the doping concentration of Ga increases, the volume change of the system is not obvious; however, when is energy increases, the system will be unstable, the Burstein-Moss effect of its optical band gap will increase, and the absorption spectrum will shift to high energy. The results of calculation agree with the experimental data.
Effects of different scattering mechanisms on inversion-channel electron mobility in Al2O3/InxGa1-xAs nMOSFET
Authors: Huang Yuan  , Xu Jing-Ping  , Wang Li-Sheng  , Zhu Shu-Yan  ,   School of optical and electronic information, Huazhong University of Science & Technology, Wuhan 430074, China
Published: December 2020

An inversion-channel electron mobility model for InxGa1-xAs n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) with Al2O3 as gate dielectric is established by considering main scattering mechanisms of bulk scattering, Coulomb scattering of interface charges and interface- roughness scattering of the Al2O3/InxGa1-xAs interface. The simulated results are in good agreement with the experimental data. Analyses by using the model indicate that the total electron mobility is mainly limited by the Coulomb scattering of interface charges under weak and medium effective fields and by the interface-roughness scattering under strong effective fields. Therefore, the effective approaches of enhancing the inversion-channel electron mobility are to reduce the interface-state density and roughness of the Al2O3/InxGa1-xAs interface, to properly increase the in content and control the doping concentration of the InxGa1-xAs channel to a suitable value.
Preparation of flower-like CuS hierarchical nanostructures and its visible light photocatalytic performance
Authors: Zhao Juan  , Hu Hui-Fang  , Zeng Ya-Ping  , Cheng Cai-Ping  ,   College of Physics and Microelectronics Science, Hunan University, Changsha 410082, China
Published: December 2020

Flower-like copper monosulfide (CuS) hierarchical nanostructures composed of nanoplates were successfully synthesized by means of a simple solvothermal process, using CuCl2·2H2O as Cu-precursor, CS2 as S-source and ethylene glycol (C2H6O2) as the solvent. The morphology and structure of the product were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The optical properties of the copper monosulfide hierarchical nanostructures were investigated by UV-visible absorption spectra. In addition, the photocatalytic activity of the flower-like CuS hierarchical nanostructures were evaluated by the degradation of methyl orange solution under natural light. Results demonstrate that the as-prepared flower-like CuS hierarchical nanostructures possess high photocatalytic performance, the degradation rate is up to 100% after 90 min degradation under the irradiation of natural light, which is much higher than bulk CuS powder. The formation mechanism of flower-like CuS hierarchical nanostructures was preliminarily analysed, alss.
QD-LED devices using ZnSnO as an electron-transporting layer
Authors: Liu Bo-Zhi  , Li Rui-Feng  , Song Ling-Yun  , Hu Lian  , Zhang Bing-Po  , Chen Yong-Yue  , Wu Jian-Zhong  , Bi Gang  , Wang Miao  , Wu Hui-Zhen  ,   Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China;,   Zhejiang University City College, Hangzhou 310015, China
Published: December 2020

We have investigated the light-emitting diodes based on colloidal CdSe quantum dots (QD-LEDs), in which inorganic ZnSnO thin films and organic TPD thin films were used as the electron-transporting layer (ETL) and hole-transporting layer (HTL), respectively. The quantum dots were embedded between the inorganic ETL and organic HTL to form a sandwich structure. ZnSnO ETL was made by magnetron sputtering, while the TPD and QD films were made by spin-coating method. The QD-LEDs display sharp interface and smooth morphology. Optical and electrical characterizations show that QD-LEDs have low turn-on voltage, good monochromaticity, bright electroluminescence and good stability in atmosphere ambient. These characteristics are attributed to the utility of high electron mobility and low carrier concentration of the ZnSnO films used as the ETL. To investigate the devices operation mechanism, the conductivity of ZnSnO was varied during deposition to realize equal injection rate for both electrons and holes, which allows the device to operate optimally.
Relations between the structure, symmetry and the energy mechanism of the polar-organic molecule ultra-films during the tribology
Authors: Zhang Zhao-Hui  , Li Hai-Peng  , Han Kui  ,   The basic educaition department of SuQian College, Suqian 223800, China;,   College of Science, China University of Mining & Technology, Xuzhou 221008, China
Published: December 2020

The molecular dynamics simulation has been used to study the tribological properties of the seven kinds mixed Langmuir-Blodgett (LB) monolayers, which composed of the fatty acids CnH2n+1COOH and C17H31COOH (n=12,13,14,15,16,17) by the ratio of 1:1, and the monolayers compoesd by C16H33COOH. The results showed that: (1) the shear pressure of mixed LB monolayers decreased as the chain-length of molecules Cn increased. The friction force main come from the coulombic interaction between the monolayers. (2) the arrangement of the two kinds of tails of the molocules influence the friction character. The shear pressure is smaller when all the tails are isotactic-arrangement than anisotactic-arrangemnet, espacilly when the differrence of the chain-length is one C-C bondlength. (3) The shear pressure decreseased as the chainlength decreased, and the friction froce main come from the coulombic interaction, when tails of the up and down isotactic monolayers which are composed of one kind molecule are mirror symmetry, or the friction froce main come from the van der wasls (VDW) interaction when tails are central symmtry.
Application of the multi-parameters error model in cyclone wind retrieval with scatterometer data
Authors: Zhong Jian  , Fei Jian-Fang  , Huang Si-Xun  , Huang Xiao-Gang  , Cheng Xiao-Ping  ,   Institute of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Combined with the multiple solution scheme (MSS) and the rain considered Geophysical model function (GMF+Rain), the two-dimensional variational (2DVAR) ambiguity removal technique is applied to the cyclone wind retrieval under rain condition with QuikSCAT scatterometer data. With the GMF+Rain model, the retrieved wind speed is effectively improved, but large wind direction error still exists when the background is in large error. In this paper, a changeable multi-parameter error model is introduced in the 2DVAR to reduce the wind direction error, and the sensitivity experiments of 2DVAR to its error model parameters are studied with cyclone Yagi QuikSCAT data, to choose the best parameters setting for cyclone wind retrieval with theoretical explanation. Numerical results show that 2DVAR is more effective in wind direction ambiguity removal with the proposed multi-parameter error model when the gross error probability in the multi-parameter error model is set to zero in comparison of the standard setting. The influence of the background is decreased with increasing backround error variance, decreasing the background error correlation length, or decreasing the gross error probabilities in multi-parameter error model.
Conformal invariance and conserved quantity of Mei symmetry for Appell equations in holonomic system
Authors: Han Yue-Lin  , Sun Xian-Ting  , Zhang Yao-Yu  , Jia Li-Qun  ,   School of Science, Jiangnan University, Wuxi 214122, China;,   School of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China
Published: December 2020

For a holonomic system, the conformal invariance and conserved quantity of Mei symmetry for Appell equations are studied. Firstly, by the infinitesimal one-parameter transformation group and the infinitesimal generator vector, we define Mei symmetry and conformal invariance of differential equations of motion for holonomic system, and the determining equation of Mei symmetry and conformal invariance for holonomic system are given. Then, taking advantage of a structure equation that gauge function satisfies, the system corresponding Mei conserved quantity is derived. Finally, an example is given to illustrate the application of the result.
Hopf bifurcation and the problem of periodic solutions in a recharge-discharge oscillator model for El Niño and southern oscillation with time delay
Authors: Li Xiao-Jing  , Chen Xuan-Qing  , Yan Jing  ,   College of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, China
Published: December 2020

In this paper, a recharge-discharge oscillator model for El Niño and southern oscillation with time delay is investigated. We obtain the critical time delay associated with Hopf bifurcation, and discuss the problem of periodic solutions for the model by using Maehin’s continuation theorem.
Symmetries, reductions and exact solutions of Broer-Kau-Kupershmidt system
Authors: Li Ning  , Liu Xi-Qiang  ,   School of Mathematical Sciences, Liaocheng University, Liaocheng 252059, China
Published: December 2020

In this paper, using the modified Clarkson-Kruskal direct method, the symmetries and the reductions of (2+1) dimensional Broer-Kau-Kupe-rshmidt (BKK) are obtained. At the same time, a great many of solutions are derived by solving the reduction equations, including the rational functions hyperbolic functions, the trigonometric functions, the power series solution, and the Airy function solution.