bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of brain auditory evoked magnetic field based on low-Tc superconducting quantum interface device
Authors: Zhang Shu-Lin  , Liu Yang-Bo  , Zeng Jia  , Wang Yong-Liang  , Kong Xiang-Yan  , Xie Xiao-Ming  ,   State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China;,   Graduate University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Superconducting quantum interface devices (SQUID) is widely used in human brain signal detection. As one of the applications of magnetoencephalography (MEG) system, the detection of the auditory evoked response is useful for the development of MEG system and the research into auditory mechanism of human brain. Generally, the auditory evoked response includes three peaks which are P50m, N100m and P200m. We develop a single-channel MEG system in a magnetically shielded room based on the superconducting quantum interface device (SQUID) and second-order axial gradiometer. The responses of the main peak N100m under different tone frequencies are preliminarily studied by using our system. The typical evoked response of N100m to 1 kHz pure tone and 100 ms duration is measured to be 0.4 pT. Under the tone stimulus at low frequency, the delay of the peak N100m to the tone onset is 125 ms at 100 Hz, which is longer than the typical value of 100 ms. In comparison with the response to 1 kHz pure tone stimulus, the amplitude of the evoked response in a random frequency range from 1 kHz to 4 kHz is stronger and the delay is several milliseconds. This work lays the foundation of the studies of the auditory mechanism and multichannel MEG system by using software gradiometers.
Conformal invariance, Noether symmetry and Lie symmetry for holonomic mechanical system with variable mass
Authors: Chen Rong  , Xu Xue-Jun  ,   Department of Physics, Zhejiang Normal University, Jinhua 321004, China
Published: December 2020

The conformal invariance of holonomic mechanical system with variable mass is studied. Firstly, the definition of conformal invariance for holonomic mechanical system with variable mass is given; secondly, the relation between the conformal invariance and the Noether symmetry is discussed, and the Noether conserved quantity led by the conformal invariance is obtained; finally, the relation between the conformal invariance and the Lie symmetry is discussed, and the Hojman conserved quantity caused by the conformal invariance of the systems is obtained. In the paper, an example is given to illustrate the application of the results.
Theoretical analysis of magnetronlike structure
Authors: Li Wei  , Liu Yong-Gui  ,   College of Opto-electric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Magnetronlike structure is a non-cathode magnetron waveguide structure. It is the basic configuration of relativistic magnetron with axial extraction (MDO). First, the dispersion relation and the field expression of the magnetronlike structure are obtained by the field matched method. Then, the results are proved by the high electromagnetic field analysis software, and the cutoff frequency is studied by changing the structure parameters. The final results show that with keeping the other parameters constant, the π mode cutoff frequency can be promoted by reducing the outer radius, enlarging the inner radius or increasing the number of the cavities. Enlarging the cavity angle will reduce the π mode cutoff frequency. The outcomes produced in this paper will play a fundamental role in the theoretical analysis on the mode conversion and transmission of the relativistic magnetron with axial extraction.
Study of material properties of Fe, S Co-doped SnO2 by first principles
Authors: Lu Yao  , Wang Pei-Ji  , Zhang Chang-Wen  , Feng Xian-Yang  , Jiang Lei  , Zhang Guo-Lian  ,   School of Physics, University of Jinan, Jinan 250022, China
Published: December 2020

Tin oxide has become one of hot points in transparent conductive materials due to its excellent electrical and optical properties. Based on the full-potential linearized augmented plane wave method (FP-LAPW), we investigate the electronic structure and the optical properties of the material Fe-S co-doped SnO2. The results show that the two co-doped compounds are all direct transition semiconductors with half-metallic properties. Fe-S co-doping can narrow the band gap, and the density of states (DOS) shifts toward the low energy with the increase of S concentration. The charge density of co-doped system is redistributed, and the degree of Fe polarization and the capacity of bonding are enhancd with the increase of S. What is more, the peaks of imaginary part of dielectric function and optical absorption are red shifted, and the absorption edge decreases with the increase of S concentration.
First-principles study of adsorption effect of A-Z-A graphene nanoribbons field effect transistor
Authors: Qin Jun-Rui  , Chen Shu-Ming  , Zhang Chao  , Chen Jian-Jun  , Liang Bin  , Liu Bi-Wei  ,   College of Computer, National University of Defense Technology, Changsha 410073, China
Published: December 2020

By performing first-principles calculations, we demonstrate the electronic structure, the transport properties, and the adsorption effect of A-Z-A graphene nanoribons field effect transistor. It is concluded that the pure A-Z-A GNR-FET has typical bipolar characteristics, and energy gaps will become smaller due to the adsorbed molecule. For the adsorption of H, N2, NO2, H2O, SO2, O2 and NO, A-Z-A GNR-FET remains typical bipolar characteristic, but shows a little difference in transport property after it has adsorbed different types of molecles. For the adsorption of OH, transport property changes totally and does not have a bipolar characteristic any more. These results may contribute to the implementation of gas detector based on GNRs and the design of GNR-FET applied in complex environments.
Theoretical study of the Rydberg series energy levels of ns2S1/2,np2P1/2,3/2, nd2D3/2,5/2 and nf2F5/2,7/2 for alkali-metal Li, Na, K, Rb, Cs and Fr
Authors: Li Xin-Mei  , Ruan Ya-Ping  , Zhong Zhi-Ping  ,   Collage of Physical Sciences, Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In the frame work of multi-channel quantum defect theory, the energy levels of Rydberg series of ss2S1/2, np2P1/2, np2P3/2, nd2D3/2, nd2D5/2, nf2F5/2 and nf2F7/2 of alkali-metal atom are calculated by the relativistic multi-channel theory, in five different approximations, i.e., frozen core approximation, with consideration of l=-1 dipole polarization effect, l=+1 dipole polarization effect, l = 1 dipole polarization effect, stretch effect, and both dipole polarization effects and stretch effect, respectively. The present calculations show that electron correlation effect plays an important role in the energy level of Rydberg series. In summary, dipole polarization effect is more important than the stretch effect, and the l = + 1 dipole polarization effect is more important than l = - 1 dipole polarization effect. However, stretch effect is more important for energy levels of both Rydberg series ns2S1/2,(nd2D3/2,nd2D5/2) of Na, and Rydberg series (np2P1/2,np2P3/2) of Li.
Resonant behavior of split ring resonator in perpendicular propagation
Authors: Chen Juan  , Zhang An-Xue  , Tian Chun-Ming  ,   School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

We systematically investigate the transmission characteristics of the split ring resonator (SRR) for propagation perpendicular to the plane of the ring resonator. Both the vertical polarization and the horizontal polarization are considered. A retrieval procedure is used to obtain permittivity and permeability . It is found that in the normal incidence case the SRR also has strong electric and magnetic responses. The electric response occurs when electric field is parallel to the side of the SRR (vertical polarization) and the frequency band is often higher than that of magnetic resonance. The magnetic response needs a polarization rotation (horizontal polarization) and the magnetic resonant frequency is the same as that of parallel incidence. The conclusions are demonstrated and the reasons for the electric and magnetic resonances are also discussed theoretically.
Diffraction effect of high-power laser beams through contamination particles
Authors: Zhang Guo-Wen  , Lu Xing-Qiang  , Cao Hua-Bao  , Yin Xian-Hua  , Lü Feng-Nian  , Zhang Zhen  , Li Jing-Hui  , Wang Ren-Gui  , Ma Wei-Xin  , Zhu Jian  ,   National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Shanghai Institute of Laser Plasmas, Shanghai 201800, China
Published: December 2020

The near-field diffraction characteristics when a high-power laser beam traverses contaminant particles are studied by using the designing software of high-power laser drivers-Laser designer. The modulations generated by contaminant particles are sorted. Then the influence of contaminant particles with amplitude or phase modulation on the near-field intensity distribution in vacuum or in fused silica is analyzed in great detail. The results show that in both vacuum and fused silica, the phase modulated contaminant particles have a greater influence on the near-field properties of high-power laser. Moreover, it is found that in fused silica, the small-scale self-focusing hot-image modulation of high-power laser induced by phase modulated hard-edge contaminant particles is momentous. But the lateral shift of high-power laser beam caused by contaminant particles maybe inhibits the small-scale self-focusing effect to some extent, thereby reducing the laser injury risk of optical component.
Terahertz thermal wave nondestructive test
Authors: Chen Da-Peng  , Xing Chun-Fei  , Zhang Zheng  , Zhang Cun-Lin  ,   School of Material Science and Engineering, Beihang University, Beijing 100191 China;,   Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

This work aims at developing a new excitation method for thermal wave nondestructive test(NDT)-Terahertz excitation. In the paper we introduce a theoretical model of heat conduction for periodical THz excitation. BWO (backward wave oscillator) terahertz source is employed to heat a carbon fiber plate with wave absorbing coating, surface temperature variations and distributions are captured by an infrared camera, and Canny edge algorithm is used to process thermal images to show the defects. Result of flash pulse thermography serves as comparison, and the advantages of THz thermal wave NDT are discussed. The combination of THz technology and infrared thermal wave NDT is realized.
Determination of tropospheric NO2 by airborne multi axis differential optical absorption spectroscopy
Authors: Xu Jin  , Xie Pin-Hua  , Si Fu-Qi  , Li Ang  , Liu Wen-Qing  ,   Key Laboratory of Enviromental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

The airborne multi axis differential optical absorption spectroscopy (AMAXDOAS) is employed to retrieve tropospheric vertical columns of NO2. The differential slant columns of NO2 are retrieved combined with the spectra in different viewing directions by the DOAS method and the vertical columns are calculated with the radiative transfer model SCIATRAN. The dependences of AMF on altitude, surface albedo, and solar zenith angle are studied. The measurement campaign in pearl region delta region on December 10 in 2008 is reported. The NO2 vertical column distribution is obtained in zenith and nadir directions. The results from airborne multi axis DOAS are compared with those from a ground-based multi axis DOAS in Zhuhai, with a deviation of 0.08. The results show that AMAXDOAS can be used to measure the tropospheric NO2 in a large area within a short time.
Theoretical analysis of underwater sound absorption of 0-3 type piezoelectric composite coatings
Authors: Yu Li-Gang  , Li Zhao-Hui  , Ma Li-Li  ,   School of Electronic Engineering and Computer Science, Peking University, Beijing 100871, China
Published: December 2020

Recently piezoelectric shunt damping has attracted a lot of attention in vibration and noise control. In this article, piezoelectric shunt damping is used in underwater sound absorption in order to enhance the sound absorption of the coating. A one-dimensional electro-acoustic model is established for the calculation by combining the equivalent circuit of thickness mode of a piezoelectric composite coating with the transfer matrix of plane wave propagation. This model can be used to calculate the sound absorption of multiple layers of piezoelectric and non-piezoelectric mediums. Underwater sound absorption of the 0-3 type piezoelectric composite coatings is theoretically analyzed. Elastic, piezoelectric and dielectric constants of the 0-3 type piezoelectric composites are calculated by Furukawa's model. Results show that the negative capacitance circuit can adjust the surface acoustic impedance of the piezoelectric composite coating at broadband frequencies. Suitable shunt resistances can make it match the characteristic acoustic impedance of water better. Therefore, the sound absorption can be greatly promoted.
Density functional calculations of geomatric structure, electronic structure, stability, and magnetic properties of transitional atom endohedral unclassical fullerene M@C22(M=Sc,Ti, V, Cr, Mn, Fe, Co and Ni)
Authors: Tang Chun-Mei  , Guo Wei  , Zhu Wei-Hua  , Liu Ming-Yi  , Zhang Ai-Mei  , Gong Jiang-Feng  , Wang Hui  ,   Department of Applied Physics, Hohai University, Nanjing 210098, China
Published: December 2020

The generalized gradient approximation (GGA) based on density functional theory(DFT) is used to analyze the structural and electronic properties of the unclassical endohedral fullerene M@C22(M=Sc, Ti, V, Cr, Mn, Fe, Co and Ni). It is found that the ground-state structure of the unclassical fullerene C22 is a spin singlet cage containing one four-membered ring and the doping of transition metal atom can obviously enhance the stability. It is discovered that the C-M bond have both the covalent and the ionic characteristics. The analyses of magnetism, energy levels, orbital wave functions and density of states show the hybridization between the 3d orbital ofM atom and the C atomic orbital in C22. In addition, Ti, Cr, Fe and Ni atoms become non-magnetic after they have been doped into the C22.
High-pressure state equation of high strength concrete investigated with the gas gun experiment
Authors: Jiang Guo-Ping  , Jiao Chu-Jie  , Xao Bo-Qi  ,   Earthquake Engineering Research Test Center, Guangzhou University Guangzhou 510405, China;,   Department of Physics and Electromechanical Engineering, Sanming University, Sanming 365004, China
Published: December 2020

The shock properties of C100 concrete are investigated by the gas gun planar impact technique. The manganin pressure gauge is used to measure the pressure-time curves of the samples. The physical quantities are all obtained by the Lagrange method. Moreover, it is observed from the measured pressure-time curves that the rate-sensitivity of dynamic response for C30 concrete is not negligible, showing marked stress relaxation and dissipation. The damage factor is introduced into the state equation. The material parameters in the Grüneisen-type equation of state are determined.
First-principles predictions for the tensile strength of Al metal with dislocations of twist grain boundaries
Authors: Wang Ru-Zhi  , Xu Li-Chun  , Yan Hui  , Kohyama Masanori  ,   Laboratory of Thin Film Materials, College of Materials Science and Engineering,Beijing University of Technology, Beijing 100022, China;,   Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577 Japan
Published: December 2020

By the first-principles calculations based on the density functional theory, the tensile strength of Al metal with dislocations of twist grain boundaries (GBs) is predicted from its electronic structure to its essential mechanical properties. The results show that the theoretical tensile strength for Al twist GB is about 8.73GPa and it is less than that for Al glide GB(9.5GPa) (Phys. Rev. B 75, 174101 (2007)). However, its fracture strain for Al twist GB is 24% and 16% more than that for Al glide GB. It suggests that the mechanical properties of the metal can be greatly improved by experimentally modulating its defect or dislocation. Furthermore, the physics of the fracture of Al twist GB is analyzed by the distributions of charge density and the changes of bond length, and it is found that the facture appears in the GB. Our theoretical predictions can play an important role in guiding the improvement of mechanical properties and structural designs for Al metal.
Doping effect of boron in Hg0.75Cd0.25Te: first-principles study
Authors: Tang Dong-Hua  , Xue Lin  , Sun Li-Zhong  , Zhong Jian-Xin  ,   Laboratory for Quantum Engineering and Micro-Nano Energy Technology Xiangtan 411105, China;,   Faculty of Materials, Optoelectronics and Physics of Xiangtan University, Xiangtan 411105, China
Published: December 2020

Using the first-principles method based on the density functional theory, we study the doping effect of B impurity in HgCdTe (MCT).We find that the most stable configuration of the impurity is at the B hexagonal interstitial position, rather than at the in-situ substitution. The electronic structures and the density of states of B hexagonal interstitial doped MCT are systematically investigated. Near neighbour (NN) and next-near-neighbor (NNN) atoms around the B impurity are obviously relaxed. The relaxation induces the breaking of NN Te-Hg covalent bond. Moreover, B hexagonal interstitial behaves as triple n-type dopant. The charged state analysis indicates that Bih(2Hg1Cd) with three positive charges is most stable and forms an effecient donor. However, as long as the Hg vacancy exists, complex impurity between Hg vacancy and B impurity can be easily formed, its binding energy reaches up to 0.96 eV. Such complex behaves as single n-type dopant. Considering radiation damage of B ion implantation, the complex is a main factor restricting the activation of B ion in MCT.
Heterojunction structure forming in the polymer film doped with small-molecule organic semiconductors
Authors: Liu Ning  , Zhang Xin-Ping  , Dou Fei  ,   Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Blends and doping of organic semiconductors are generally employed to improve effectively the charge transfer and dissociation performance. The absorption spectrum may be optimized making use of the different energy states of the components in the blends, which may favor the development of the photovoltaic or solar cell devices. Excellent type-II heterojunction structures can be produced by mixing the small-molecule perylene (EPPTC) and a copolymer of polyfluorene (F8BT). Actually, F8BT and EPPTC exhibit absorptions in the blue region and in the green region, respectively. Thus, the blend will have a much broadened absorption spectrum. In the experiment, the blend solution of these two materials in chloroform is spin-coated onto a piece of glass substrate, so that EPPTC is doped into the polymer of F8BT and the heterojunction structure forms in the final solid film. Then, steady-state absorption and fluorescence spectroscopy, as well as the transient photoluminesence spectroscopy (time-correlated single-photon counting), is used to investigate the formation and the photoluminescence properties of exciplex in the heterojunction film of F8BT doped with EPPTC. The photoluminscence (PL) spectrum and the life-time are measured to characterize the exciplex in the blend film, where the longer life-time of the red-shifted PL spectrum confirms the formation of the exciplex. This provides various experimental data for understanding the formation and the photophysical properties of the heterojunction structures in organic semiconductor blends. Futhermore, the absorption of the blend film covers a large range of the visible spectrum. Therefore, this kind of doping of organic semiconductor is important for the development of photovoltaic and solar cell devices.
Effect of internal stress on sructure, martensitic transformation and magnetic properties of ferromagnetic shape memory alloy Mn2NiGa
Authors: Song Rui-Ning  , Zhu Wei  , Liu En-Ke  , Li Gui-Jiang  , Chen Jing-Lan  , Wang Wen-Hong  , Li Xiang  , Wu Guang-Heng  ,   State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Bejing 100190, China;,   School of Material Sciences & Engineering, Beijing Institute of Technology, Beijng 100081, China
Published: December 2020

The structures, the martensitic transformations and the magnetic properties of ferromagnetic shape memory alloy Mn2NiGa with the loading and the unloading of the external compressive stress are investigated. The plastic deformation occurring during the stressing causes a high level of dislocation defects existing in the sample. The residual internal stress results in a significant increase of the reversed transformation temperature. The threshold value of compressive pressure for causing the completely martensitic transformation at room temperature is identified to be 1.0 GPa based on the experimental measurements of XRD and magnetic coercivity. The coercivity of the martensitic phase increases from 50 Oe to 350 Oe due to the application of the external stress up to 2.0 GPa. It is also observed that the reversed martensitic transformation occurrs, when the sample is treated by heating up to about 730 K. This is attributed to the elimination of the dislocation by the annealing effect. Such a high reverse martensitic transformation temperature allows the measurement of the Curie temperature of martensitic phase and the obtained value is 530 K.
Magnetic property and structure of Heusler alloy: Fe2CrGa
Authors: Zhu Wei  , Liu En-Ke  , Zhang Chang-Zai  , Qin Yuan-Bin  , Luo Hong-Zhi  , Wang Wen-Hong  , Du Zhi-Wei  , Li Jian-Qi  , Wu Guang-Heng  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academic of Science, Beijing 100190, China;,   School of Physical Science and Technology, Inner Mongolia University, Huhhot 010021, China;,   School of Material Science and Engineering, Heibei University of Technology, Tianjin 300130, China;,   Central Research Institute of Nonferrous metals, Beijing 100088, China
Published: December 2020

The KKR-CPA-LDA method was used to calculate the electronic and the magnetic structures of Fe2CrGa alloy. The results indicate that Fe2CrGa alloy prefers to crystallize in Hg2CuTi-type structure rather than L21 one. The analysis of density of states reveals that the intra-atomic exchange splitting affected by crystal field plays an important role in forming the Hg2CuTi-type structure. The molecular magnetic moments measured experimentally are in a range of 2.282.48B/f.u., which is very close to that expected theoretically by the calculations based on the Hg2CuTi-type structure, but not based on the L21 structure. The experimental results also show that the Curie temperature of Fe2CrGa alloy can be continuously manipulated from 308K to 445K by heat-treating under the various conditions, indicating a high sensitivity of the exchange interaction to the atomic ordering in this system.
Effects of oxygen vacancy on impurity distribution and exchange interaction in Co-doped TiO2
Authors: Sun Yun-Bin  , Zhang Xiang-Qun  , Li Guo-Ke  , Yang Hai-Tao  , Cheng Zhao-Hua  ,   State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Dilute magnetic semiconductors have auracted much attention because of their potential applications in spintronics. In this paper, the effects of oxygen vacancy on total energy and magnetism in Co-doped TiO2 are investigated using the density functional theory. The energy of the system with a shorter Co-Co distance is higher than that with larger Co-Co distance after introducing oxygen vacancy. Oxygen vacancy trends to congregate around the Co cations. Moreover, the strength of exchange couple reduces in the system with a shorter Co-Co distance after introducing oxygen vacancy. For the system with a larger Co-Co distance, the exchange couple between two Co impurities is anti-ferromagnetic if oxygen vacancy is located at the basal site of octahedron containing Co, and ferromagnetic if oxygen vacancy is located at the apical site of octahedron containing Co.
Theoretical research of correlation of electronic structure with birefringence and anisotropy of TiO2
Authors: Zhang Yong-Wei  , Yin Chun-Hao  , Zhao Qiang  , Li Fu-Qiang  , Zhu Shan-Shan  , Liu Hai-Shun  ,   College of Science, China University of Mining and Technology, Xuzhou 221008, China
Published: December 2020

The crystal structure, the band structure, and the density of states of anatase TiO2 are analysed by using the plane-wave ultrasoft pseudopotential method of the first principles based on the density functional theory. Then we calculate optical properties such as dielectric function, energy loss function, photoconductivity systematically based on the results of electronic structure, and analyse the correlation of electronic structure with birefringence and anisotropy. The obtained results are consistent well with the reported results in the literature, revealing the natures of electronic structure of TiO2 and its birefringence as well as anisotropy theoretically.
Hydrogenated poly-crystalline silicon thin films deposited by inductively coupled plasma assisted pulsed dc twin magnetron sputtering
Authors: Su Yuan-Jun  , Xu Jun  , Zhu Ming  , Fan Peng-Hui  , Dong Chuang  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 China;,   Nissin Electric-Dalian University of Technology Joint R&D Center, Dalian 116024 China
Published: December 2020

Hydrogenated poly-crystalline silicon thin films are deposited by inductively coupled plasma assisted pulsed dc twin magnetron sputtering at a temperature below 300 ℃. The samples are characterized by X-ray diffraction, Raman scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy. The relationship between hydrogen dilution ratio and the characteristic of thin film is studied systematically. The mechanism of crystallization is discussed on the basis of the results of diagnosis of plasma by Langmuir probe and optical emission spectra.
Influence of gate voltage on gate-induced drain leakage current in ultra-thin gate oxide and ultra-short channel LDD nMOSFET's
Authors: Chen Hai-Feng  , Guo Li-Xin  ,   School of Electronic Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710121, China
Published: December 2020

The influence of gate voltage VG on gate induced drain leakage (GIDL) current is studied in LDD nMOSFET with a gate oxide of 1.4nm and a channel length of 100nm. It is found that the split phenomena of ln(Id/(VDG-1.2))-1/(VDG-1.2) curves under different VG values occurs, which are different from the large MOSFET. Through comparing varieties of ln(Id/(VDG-1.2)) of different VG values, the mechanism of this split phenomenon is obtained. This is ascribed to the change of the hole-tunneling part of GIDL current under different VG values. The absolute value of ln(Id/(VDG-1.2)) curve slope decrease with |VG| value decreasing . It is further found that the values of slope c and intercept d of ln(Id/(VDG-1.2)) curves are linear with VG and the slopes of c and d are 3.09 and -0.77, respectively. The values of c and d quantificationally show the influence of VG on the GIDL current in an ultra-thin ultra-short MOSFET. On the basis of these results, a new GIDL current model including VG is proposed.
The influence of the structure of the organic ultra-film on friction
Authors: Zhang Zhao-Hui  , Han Kui  , Cao Juan  , Wang Fan  , Yang Li-Juan  ,   The basic educaition department of Suqian College, Suqian 223800, China;,   College of Science, China University of Mining & Technology, Xuzhou 221008, China
Published: December 2020

Molecular dynamics simulation is used to study the friction of mixed Langmuir-Blodgett film composed of hydrocarboxylic acid (CnH2n+1COOH, n=12,13,14,15,16,17) and the C17H31COOH, in order to investigate the influence of the structure on friction. The results show that the restiction of long chain molecules by the neighbor molecules increases and the monolayers become more steady as n increases, while the shear pressure between the monolayers decreases and reaches a minimum when n=17. The hydrogen-bond formed in the mixed monolayers is the main reason why the monolayers become more steady, espatially,the hydrogen-bonds are most steady when n=16, but the monolayer composed that just of C17H31COOH molecules has the best sliding effect; there is no hydrogen-bond between the two monolayers. The shear pressure is hardly affected by the molecular deformation.
Growing two-dimensional manifold of nonlinear maps based on generalized Foliation condition
Authors: Li Hui-Min  , Fan Yang-Yu  , Sun Heng-Yi  , Zhang Jing  , Jia Meng  ,   School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

In this paper we present an algorithm of computing two-dimensional (2D) stable and unstable manifolds of hyperbolic fixed points of nonlinear maps. The 2D manifold is computed by covering it with orbits of one-dimensional (1D) sub-manifolds. A generalized Foliation condition is proposed to measure the growth of 1D sub-manifolds and eventually control the growth of the 2D manifold along the orbits of 1D sub-manifolds in different directions. At the same time, a procedure for inserting 1D sub-manifolds between adjacent sub-manifolds is presented. The recursive procedure resolves the insertion of new mesh point, the searching for the image (or pre-image), and the computation of the 1D sub-manifolds following the new mesh point tactfully, which does not require the 1D sub-manifolds to be computed from the initial circle and avoids the over assembling of mesh points. The performance of the algorithm is demonstrated with hyper chaotic three-dimensional (3D) Hnon map and Lorenz system.
High resolution imaging technique based on phase diversity hybrid method
Authors: Li Fei  , Rao Chang-Hui  ,   The Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China;,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   College of Opto-Electronics Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In order to improve the resolution of an imaging system and make the system as simple as possible, the wavefront sensing and the image post-processing using phase diversity are combined to form a new method, i.e., phase diversity hybrid method, in this paper. The performance of this method is simulated for a point source and also for an extended source. An experimental platform is built based on a point source. The experimental results demonstrate that the acceptable results cannot be achieved by using single post-processing for large aberration. The full width half maximum of the light spot descends from 5.1 pixels, 5.1 pixels, and 5.0 pixels which are corrected by adaptive optics to 3.3 pixels, 3.2 pixels, and 3.0 pixels respectively. We can see that the quality of the image processed by phase diversity hybrid method is much better than that restored by post-processing method or corrected by adaptive optics only. It has a great potential application in the filed of high resolution imaging.
Simulation of culmulated microimpacts of micro debris to solar cells and function degradation
Authors: Huang Jiam-Guo  , Liu Dan-Qiu  , Gao Zhu-Xiu  , Li Hong-Wei  , Cai Ming-Hui  , Han Jian-Wei  ,   Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China;,   raduated University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The cumulated impacts of the space micro debris on the solar cells is experimentally simulated on the plasma dynamic accelerator in CSSAR. For a duration of ten years on the typical sun synchronous orbit, the solar cell functional degradation due to the micro impacts is measured, and the result accords well with the predicted result according to the impacting damage equation.
Conformal invariance and conserved quantity of Mei symmetry for the nonholonomic system of Chetaev's type
Authors: Cai Jian-Le  , Shi Sheng-Shui  ,   College of Science, Hangzhou Normal University, Hangzhou 310018, China
Published: December 2020

For a nonholonomic system of Chetaev's type, the conformal invariance and the conserved quantity are studied. By the infinitesimal one-parameter transformation group and the infinitesimal generator vector, the definition of conformal invariance of Mei symmetry and the determining equation for the holonomic system which corresponds to a nonholonomic system are provided, and the relationship between the system conformal invariance and Mei symmetry is discussed. Using the restriction equations and the additional restriction equations, the conformal invariances of weak and strong Mei symmetrys for the system are given. With the aid of a structure equation that gauge function satisfies, the system corresponding conserved quantity is derived. Finally, an example is given to illustrate the application of the result.
Current referenced pulse train control technique applied to switching converter
Authors: Qin Ming  , Xu Jian-Ping  , Gao Yu  , Wang Jin-Ping  ,   School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

A new control technique, current referenced pulse train (CR-PT), applied to switching dc-dc converter is proposed and analyzed in this paper. By sensing and comparing the output voltage and the load current at each switching cycle, an appropriate pulse is selected from among several preset pulses as an active control signal of converter. A buck converter is taken as an example to illustrate the principle, the application, the regulation, the steady state performance and the transient performance of CR-PT control scheme. The study results show that the CR-PT control enjoys the fast transient response, the convenient implementation and the stability, and the steady state performance of CR-PT control is much better than that of pulse train control.
The time evolution of relative density operator in phase diffusion channels
Authors: Zhou Jun  , Yuan Hao  , Song Jun  ,   Department of Material and Chemical Engineering, West Anhui University, Liu an 237012, China
Published: December 2020

By virtue of the properties of thermal entanglement, we succeed to obtain the solution to the representative phase diffusion master equation and give the operator sum representation of density operator. After analyzing the time evolution process of density operator at different initial state, we find out density operators keep invariable with the initial state being Fock state or thermal state. But the system always maintains coherence with phase diffusion when the initial state is coherent state.
An sus(1,1) ⊕ sud(1,1) algebraic structure of the cuprate superconductors model based on the analogy with atomic nuclei
Authors: Jin Shuo  , Xie Bing-Hao  , Zhang Hong-Biao  ,   School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China;,   School of Applied Science, Beijing Information Science and Technology University, Beijing 100101, China;,   School of Physics, Northeast Normal University, Changchun 130024, China
Published: December 2020

A cuprate superconductor model based on the analogy with atomic nuclei was presented to have an su(3) algebraic structure by Iachello. Our previous work showed that the mean-field approximation Hamiltonian can be expressed as a linear function of the generator of su(3) algebra. Through the realization of the algebra generator, an sus(1,1) ⊕ sud(1,1) algebraic structure is shown. By using the unitary transformation of the coherent operator U(θ,φ), the gap equations and the eigenvalues of the reduced Hamiltonian are obtained. The analysis of the physical model through different algebraic structures leads to different particular results.
Stochastic resonance in a time-delayed asymmetric mono-stable system modulated by periodic rectangular signal
Authors: Zhang Xiao-Yan  , Xu Wei  , Zhou Bing-Chang  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

We investigated the stochastic resonance of the time-delayed mono-stable system modulated by periodic rectangular signal and Gaussian white noises. The expression of signal-to-noise ratio (SNR) is obtained, and the stochastic resonance phenomenon is found in this system. The study shows that the effects of multiplicative and white noise intensity on the SNR are different. In the SNR-D plot, the phenomenon of resonance and suppression exists together. When the value of the bias of system |r| is bigger or the ratio of multiplicative and white noise intensity D/ is less than 1, the stochastic resonance phenomena in the SNR- plots disappear.
Robust suppressing chaos in permanent magnet synchronous motor with v/f control based on passivity theory
Authors: Wei Du-Qu  , Zhang Bo  ,   College of Electric Power, South China University of Technology, Guangzhou 510640, China
Published: December 2020

A passivity-based adaptive control law is presented, which transforms the permanent magnet synchronous motor (PMSM) with v/f controller into an equivalent passive system. It is proved that the equivalent system can be asymptotically stabilized at different equilibrium points without any influence of undeterministic parameters. Simulation results show the proposed control law is very effective and robust against the uncertainty in system parameters.
Growth mechanism of hydrogenated carbon films: molecular dynamics simulations of the effects of low energy CH radical
Authors: Song Qing  , Ji Li  , Quan Wei-Long  , Zhang Lei  , Tian Miao  , Li Hong-Xuan  , Chen Jian-Min  ,   School of Mathematics, Physics and Software Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China;,   State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

Molecular dynamics simulations are carried out to investigate the effect of low energy CH radical on the growth of hydrogenated carbon film. The results show that the adsorption rate of CH on clear diamond(111) is about 98%, while on hydrogenated diamond (111) the adsorption rate is lower than 1%. It indicates that the selective adsorption of low energy CH radical at the unsaturated surface C site is the dominated mechanism of the hydrogenated carbon film growth in PECVD.
Improvement of wind retrieval algorithm for Rayleigh Doppler lidar
Authors: Shen Fa-Hua  , Shu Zhi-Feng  , Sun Dong-Song  , Wang Zhong-Chun  , Xue Xiang-Hui  , Chen Ting-Di  , Dou Xian-Kang  ,   Department of Physics, Yancheng Teachers University, Yancheng 224002, China;,   Anhui Institute of Optics and Fine Mechanics, the Chinese Academy of Sciences, Hefei 230031, China;,   School of Space and Earth Science, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

In the process of wind retrieval for Rayleigh Doppler lidar, besides atmospheric temperature and pressure, the accuracy of the wind retrieval result is also affected by Mie signal. When the Mie scattering sigal is large, especially in the cases such as high altitude clouds or volcanic ash and so on, the wind retrieval result will largely deviate from the ture value if the aerosol signal is ignored due to temperature uncertainty and Mie signal contamination. A nonlinear iterative algorithm is proposed, which can retrieve both wind and atmospheric temperature by using the mesured signal with outgoing laser pointing to the zenith. The initial operating point of laser is optimized. Simulation results show that the proposed algorithm can retrieve scattering ratio effectively, and by combination with the nonlinear iterative algorithm of wind retrieval, this algorithm can eliminate the effect of aerosol backscattering signal and then improve the atmopheric wind speed and the temperature retrieval accuracy effectively.
Study of synthesis and mechanism of MgFe2O4 nanoparticles by ultrasonic Intensify
Authors: Xu Bo  , Wang Shu-Lin  , Li Sheng-Juan  , Li Lai-qiang  ,   College of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   College of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

MgO nano-particles are prepared by ultrasonic cavitate, and-Fe2O3 nano-particles are prepared by chemical precipitation method, then MgO and-Fe2O3 are mixed in a beaker. After the ultrasonic dispersion for 2 h, MgO/-Fe2O3 admixture is calcined at 400℃ to synthesize MgFe2O4 nano-particles. TEM and XRD tests show that MgFe2O4 takes on a spinel structure and the particles sizes range from 20 to 30 nm. The theoretieal analysis indicates that the ultrasonic cavitate effect enhances the reaction activity of raw material, augmentes specific surface area and the contact area of reactant, which can promote reaction rate, reduce reaction temperature, and make possible the chemical reaction that is difficult to complete in common condition.
Simulation and optimization of the cascaded luminescent solar concentrator photovoltaic system
Authors: Geng Jun-Jie  , Zhang Jun  , Zhang Yi  , Ding Jian-Jun  , Sun Song  , Luo Zhen-Lin  , Bao Jun  , Gao Chen  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China;,   CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China;,   School of Physical Science, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Luminescent solar concentrator (LSC) photovoltaic system can cut down the cost of photovoltaic electricity generation by reducing the consumption of solar cells. Compared with the single-layer LSC, the cascaded LSC can make use of the solar spectrum effectively and obtain high photoelectric conversion efficiency. In this paper, the physical processes of the single-layer and cascaded LSC are analyzed and the corresponding mathematical models are established. Based on the models, the simulation software is developed to calculate the photoelectric conversion efficiencies of the LSC and the cascaded LSC. The effects of the size of the optical waveguide and the bandgap of solar cells on the total conversion efficiency are investigated.
Study of SP3 for spatially-resolved diffuse reflectance close to light source
Authors: Zhang Xiao-Juan  , Zhou Qing-Jun  , Yang Wei  ,   College of Science, Civil Aviation University of China, Tianjin 300300, China
Published: December 2020

Based on P3 approximate spatially-resolved diffuse reflectance theory for semi-infinite biological tissue, the simplified expression SP3 function for highly absorbing medium close to source is studied. The research result shows that function SP3 can better describe the spatially-resolved diffuse reflectance close to source for higher absorption; the inversion of the optical parameters of highly absorbing medium with function SP3 shows the existence of extreme values of the curves fitted with diffuse reflectance data for different start distances, and the inversion results near the extreme values are the most closest to the optical parameters of real tissues.
Manipulation of the vector chaotic polarization of VCSEL output with external optical feedback by electro-optic modulation
Authors: Zhong Dong-Zhou  , Wu Zheng-Mao  ,   School of Informatics, Wuyi University, Jiangmen 529020, China;,   School of Physics, Southwest University, Chongqing 400715, China
Published: December 2020

Based on the wave coupling theory of linear electrooptic effect in quasi-phase- matched periodical poled LiNbO3(PPLN), the control of the vector chaotic polarization of VCSEL output with external optical feedback by electro-optic modulation is numerically investigated. The investigation results show that the polarization state of VCSEL output switching periodically with the applied external electronic field or the length of the crystal. The original chaotic polarized state of its output caused by different parameters of VCSEL can be conversed into the other arbitrary chaotic polarized state. In particular, by controlling a certain applied external electronic field or the length of the crystal, any chaotic polarization model of VCSEL output can be conversed into two complete identical linear chaotic polarization model(x and ŷ polarization). In the case, this indicates that the energy of two linear chaotic polarization model can be steadily realized balanced status.
Experimental investigation on coherent beam combination of a three-element fiber array based on target-in-the-loop technique
Authors: Geng Chao  , Li Xin-Yang  , Zhang Xiao-Jun  , Rao Chang-Hui  ,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A kind of target-in-the-loop (TIL)technique which promises the coherent combination of multi-element laser beams in far field is experimentally demonstrated. The physical model of coherent beam combination (CBC)based on TIL is established. A kind of adaptive fiber optics collimator (AFOC)correcting optical path and tip/tilt errors simultaneously is employed to compensate phase errors between beamlets. The CBC of a 3-element fiber array based on TIL is successfully achieved and a perfect effect of CBC is captured. In this paper, we present a reference for long-distance transmission of multi-element coherent beams in real atmospheric environment.
Preparation of controllable three-mode entangled coherent states
Authors: Qu Zhao-Jun  , Ma Xiao-Guang  , Xu Xiu-Wei  , Yang Chuan-Lu  ,   College of Physics, Ludong University, Yantai 264000, China
Published: December 2020

For a system composed of a three-mode cavity field interacting with a movable mirror, the time evolution operator of the system and its transformation are given, and the time evolution of the system state is obtained by means of quantum theory. The result shows that the state of the three-mode cavity field is in an entangled coherent state when the mirror returns to its original state, and the preparations of different entangled coherent states can be controlled. Nine different three-mode entangled coherent states are given, and the different phase factors of these states indicate the different reactions between the field and the movable mirror, which provides an important theoretical basis for the experimental preparations of controllable entangled coherent states.