bluuebunny/crossref_metadata_2025 huggingface dataset:
Traditions of the Soviet Academy of Art History in the theses of the Chinese students of I. E. Repin Institute of Painting, Sculpture and Architecture at the turn of the 1950s – 1960s (based on the archival materials)
Authors: Wang Shujing
Published: June 2021

This article is dedicated to the relevant problem of art history, and determines the degree of impact of the traditions of the Soviet Academy of Art History upon the art education of the People's Republic of China. The fundamental role in this process is assigned to the Chinese students who studied in I. E. Repin Leningrad State Institute of Painting, Sculpture and Architecture of the USSR Academy of Arts during the 1950s – 1960s, as well as their pedagogues and academic advisors. The article analyzes the stenographic materials of state attestation of the four Chinese students of the faculty of Theory and History of Art, who defended their theses in 1959 and 1960. The novelty of this research lies in the fact that the the materials of the Scientific Archive of the Russian Academy of Arts that were not previously used in scientific discourse, namely work with the stenographic materials of state attestation of the selected students, reveal certain peculiarities of art history and art education of the People's Republic of China, description of the tradition of the Soviet Academy of Art History and its impact upon the Chinese education at the turn of the 1950s – 1960s. The Chinese graduates of I. E. Repin Leningrad State Institute of Painting, Sculpture and Architecture have later continued the traditions of the Soviet Academy of Art History, and laid the foundation for education of the future generations of specialists in the field of art. The conducted research determines several relevant trends of the Soviet School that influenced the development of Chinese art history.
The specificity of geocultural images of the cold in folklore and literature of the indigenous peoples of Yakutia of the Soviet period
Authors: Kuzmina Aitalina Akhmetovna
Published: June 2021

This article examines the specificity of geocultural images of the cold in folklore and literature of the indigenous peoples of Yakutia (Yukaghirs, Evens, Evenks, Yakuts) of the Soviet period. The goal consists in studying the specificity of geocultural images of the cold in folklore and literature of the indigenous peoples of Yakutia of the Soviet period and tracing the dynamics of development of such representations. The subject of this research is the geocultural images that characterize the attributes of cold, such as “cold”, “winter”, “snow”, “ice”, “permafrost”. The study leans on works of the scholars dedicated to examination of the folklore worldview, “northern text”, anthropology and conceptology of the cold, and the questions of mythopoeia. The author employs linguoculturological, cultural-historical, semiotic, and geopoetic approaches. The novelty of this research consists in comprehensive examination of the peculiarities of representations on geocultural images with attributes of the cold and extensive coverage of the folklore and literary material based on the folklore materials and literature of the Indigenous peoples of Yakutia of the Soviet period. It is revealed that the indigenous peoples of Yakutia have different representations on these natural phenomena. In the folklore worldview, the representations on the cold mostly have negative connotation. The Yakut national literature of the early XX century adhered to the canons of the traditional worldview, and since the second half of the XX century, the severe climate of the North started to be perceived as something unique and positive. The acquired results can be applied in the field of folklore studies, literary studies, and anthropology in examination of the peculiarities of cultural texts of the North and the Arctic.
Phonological peculiarities (segmental level) of the French language in Pondicherry (India)
Authors: Lagutina Anna , Lalova Tat'yana
Published: June 2021

This article is dedicated to examination of phonological peculiarities of segmental level of the French language in Pondicherry, one of the regions of the Republic of India. This region is a former trading post of the Fifth Republic, and currently is part of the preserved so-called “French India”. The goal of this research consists in determination of phonetic peculiarities of the French language of the population of Pondicherry in comparison with the central norm of pronunciation in France. The authors conducted an auditory analysis of the text recorded by the broadcasters, as well as thoroughly analyzed its results. In the course of research, the authors examined the level of realization of phonological oppositions within the system of vowels; as well as peculiarities of pronunciation of consonants, preservation or non-preservation of the phenomenon of “binding”, along with the instances pronunciation or fall out of [ə] caduc. The main conclusion consists in confirmation of the assumption on the causes of certain difficulties in realization of the French norm of pronunciation among the residents of Pondicherry. The differences in phonological systems of the French and Tamil languages (native to the population of Pondicherry) are the cause of the emergence distortions or replacements of certain French phonetic sounds. The conducted determined the pronunciation characteristics of French language of the population of Pondicherry, which were affected by their native Tamil language.
Indexation of the degrees of functional modalation and interjectivation of word forms such as “horror”/ “nightmare”
Authors: Shigurov Viktor Vasil'evich , Shigurova Tat'yana Alekseevna
Published: June 2021

This article examines the result of functional transposition of language units from nouns into introductory-modal words with the meaning of affective evaluation of the conveyed and emotive interjections. The object of this analysis is the substantive word forms such as “horror” / “nightmare”, which functionin in the syncretic context of modalation and interjectivation. The subject of this analysis is the combinatorics and proportion of differential features of nouns, introductory-modal words and interjections within the structure of syncretic formations. The relevance of this work is substantiated by the need for studying syncretic zones in the grammatical structure of language; determination of the peculiarities of interaction between the grammatical and the lexical within the semantic-grammatical structure of formations place at the intersection of several transpositional processes in the sphere of the parts of speech and inter-part-of-speech categories of predicatives and introductory-modal units. The novelty of this research consists in the use of quantitative characteristics in assessing the degrees of functional modalation and interjectivation of desubstantive word forms such as “horror”/ "nightmare". The article describes the experience of calculating the indexes of their transposition into position of isolated introductory-modal components of expression with the meaning of effective evaluation of situation. It is determined that syncretic formations “horror” / “nightmare” detect in syncretic contexts of modalation and interjectivation 5% correspondence of their differential features to the features of reference nouns, 64% correspondence to the features of nuclear introductory-modal words such as “of course”, and 56% correspondence to the features of nuclear emotive interjections such as “all is ruined!”.
Effect and relational analysis of physical parameters on coalescence-induced self-propelled jumping of droplets
Authors: Wang Yu-Hang , Yuan Meng , Ming Ping-Jian ,   College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China,   Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, China
Published: June 2021

Coalescence-induced self-propelled jumping of droplets on superhydrophobic surfaces has been widely concerned because of a great number of potential applications such as in the enhancement of condensation heat transfer, self-cleaning and anti-icing. The droplet jumping phenomenon exists in a gas-liquid two-phase system, and the physical parameters of fluid cannot be ignored. However, there are few reports on the influence of physical parameters on droplet jumping dynamics at present. In this paper, the three-dimensional volume-of-fluid method is used to simulate the coalescence-induced self-propelled jumping behaviors of droplets, then the energy terms are studied, and finally the grey relational analysis method is used to calculate the relation degree of the change of physical parameters (the viscosity and the density) to the real jumping velocity and the real solid-liquid contact time at the droplet departure time, respectively. Based on the changing trend of jumping velocity, the process of coalescence-induced self-propelled jumping can be divided into four stages, namely, the expansion of liquid bridge, the impact between the liquid bridge and the surface, the droplet departure from the surface, and the deceleration and oscillation in the air. Under the condition of dimensionless time, the dynamic characteristics of coalescence and jumping of droplets are affected only by Oh number, which is independent of the viscosity and the density. In addition, the change of Oh number only affects the above third stage of droplet departure from the surface. Under the condition of real time, the varied viscosity has no connection with the real time of droplet coalescence, and it only changes the real time of the third stage before droplet jumping. Meanwhile, the dimensionless jumping velocity decreases with Oh number increasing, while the real jumping velocity increases when the viscosity and the density both descend. According to the calculated results of grey relational degree, the relation between the change of viscosity and the real jumping velocity is greater, while the relation between the change of density and the real contact time is greater. This work not only is favorable for a better understanding of droplet jumping, but also provides more ideas and theoretical bases for follow-up relevant studies.
Fast generation of three-atom singlet state with Rydberg superatom
Authors: Ji Yan-Qiang , Wang Jie , Liu Ying-Li , Zhang Da-Wei , Xiao Rui-Jie , Dong Li , Xiu Xiao-Ming ,   College of Physical Science and Technology, Bohai University, Jinzhou 121013, China,   College of Mechanical and Electric Engineering, Changchun University of Science and Technology, Changchun 130022, China,   College of Electrical Engineering, Yingkou Institute of Technology, Yingkou 115014, China
Published: June 2021

Quantum entanglement is a basic resource of quantum information processing and quantum computation. The simple and efficient generation of entangled states is always one of the hot research topics. As one of the ideal carriers of quantum information encoding, neutral Rydberg atom occupies a place in the field of generation of entangled state with its unique advantages. For example, Rydberg atom has a large volume and is easily ionized by an external electric field, so it is very sensitive to the change in the external electric field. Therefore, the interaction strength between Rydberg atoms can be changed by altering the external electric field. Rydberg state is a highly excited state, but its radiation attenuation is very small: the radiation lifetime can reach a millisecond level or even longer. The distance between the atomic kernel and the outermost electron is relatively long, and the electric dipole moment is very large. In this paper, the four-level inverted “Y”-type Rydberg atomic system is introduced into the Rydberg blocking ball to form a superatom, and the quantum information is encoded on the effective energy level of the superatom under the condition of weak cavity field. We construct shortcuts to adiabatic passage in a three-superatom system. Combined with quantum Zeno dynamics and shortcuts to adiabatic passage, the three-particle singlet state is simply and effectively generated. In addition, the influence of decoherence factors (including cavity decay and spontaneous emission of superatoms) on the fidelity is considered in this scheme. Numerical simulation results show that the proposed scheme can obtain high fidelity without precisely controlling the evolution time, and the fidelity of singlet state is robust to decoherence factors, since no cavity-photon population is involved in the whole process because of the quantum Zeno dynamics.
Mn-In-Cu co-doping to optimize thermoelectric properties of SnTe-based materials
Authors: Huang Qing-Song , Duan Bo , Chen Gang , Ye Ze-Chang , Li Jiang , Li Guo-Dong , Zhai Peng-Cheng ,   Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics, Wuhan University of Technology, Wuhan 430070, China,   State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
Published: June 2021

Lead-free chalcogenide SnTe has a similar crystal structure and energy band structure to high performance thermoelectric material PbTe, which has been widely concerned in recent years. However, due to its low Seebeck coefficient, high intrinsic Sn vacancy concentration and high thermal conductivity, its intrinsic thermoelectric performance is poor. In this study, Mn-In-Cu co-doping SnTe-based thermoelectric materials are prepared by hot pressing sintering at high-temperature and high-pressure. Indium (In) doping brings the resonant level in SnTe and increases the density of states which greatly improves Seebeck coefficient at room temperature; the Seebeck coefficient of Sn1.04In0.01Te(Cu2Te)0.05 reaches 70 μV·K–1 at room temperature. With adding manganese (Mn), the Seebeck coefficient at room temperature is well preserved, indicating that Mn doping has little effect on the resonant level brought by In doping. In addition, due to the band convergence brought by Mn doping, the high temperature Seebeck coefficient of the material is improved, the maximum Seebeck coefficient reaches 215 μV·K–1 for the sample with 17% Mn doping amount at 873 K. Owing to the combination of band convergence and resonant level, the Seebeck coefficient of the whole temperature range of the material increases, the power factor of the material is also greatly optimized, and all samples have a power factor of more than 1.0 mW·m–1·K–2 at room temperature. On the other hand, the point defects brought by Mn alloying and the interstitial defects introduced by copper (Cu) enhance the phonon scattering and effectively reduce the lattice thermal conductivity of the material, the lattice thermal conductivity decreases to 0.68 W·m–1·K–1 at 873 K. The electrical and thermal properties of the materials are optimized simultaneously under the combination of various strategies, the peak zT ≈ 1.45 is obtained at 873 K in the p-type Sn0.89Mn0.15In0.01Te(Cu2Te)0.05 sample and the average zT of 300–873 K reaches 0.76. In the process of multi-strategy coordinated regulation of SnTe-based thermoelectric materials, the excellent properties of single strategy can be well maintained, which provides a possibility for further improving the performance of SnTe-based thermoelectric materials.
Random noise suppression of magnetic resonance sounding signal based on modified short-time Fourier transform
Authors: Lin Ting-Ting , Li Yue , Gao Xing , Wan Ling ,   College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130026, China,   Key Laboratory of Geophysical Exploration Equipment, Ministry of Education, Jilin University, Changchun 130026, China
Published: June 2021

Magnetic resonance sounding (MRS) has the advantage of detecting groundwater content directly without drilling, but the signal-to-noise ratio (SNR) is extremely low which limits the application of the method. Most of the current researches focus on eliminating spikes and powerline harmonic noise in the MRS signal, whereas the influence of random noise cannot be ignored even though it is difficult to suppress due to the irregularity. The common method to eliminate MRS random noise is stacking which requires extensive measurement repetition at the cost of detection efficiency, and it is insufficient when employed in a high-level noise surrounding. To solve this problem, we propose a modified short-time Fourier transform(MSTFT) method, in which used is the short-time Fourier transform on the analytical signal instead of the real-valued signal to obtain the high-precision time-frequency distribution of MRS signal, followed by extracting the time-frequency domain peak amplitude and peak phase to reconstruct the signal and suppress the random noise. The performance of the proposed method is tested on synthetic envelope signals and field data. The using of the MSTFT method to handle a single recording can suppress the random noise and extract MRS signals when SNR is more than –17.21 dB. Compared with the stacking method, the MSTFT achieves an 27.88dB increase of SNR and more accurate parameter estimation. The findings of this study lay a good foundation for obtaining exact groundwater distribution by utilizing magnetic resonance sounding.
Fabrication process and superconducting properties of recycling multi-domain GdBCO bulk superconductors using improved infiltration technique
Authors: Wang Miao , Yang Wan-Min , Wang Xiao-Mei , Zan Ya-Ting , Chen Sen-Lin , Zhang Ming , Hu Cheng-Xi ,   School of Science, Xi’an Aeronautical University, Xi’an 710077, China,   School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, China
Published: June 2021

High temperature superconductor has become one of the hotspots of research, because of its high critical temperature, strong trapped flux density, stable suspension characteristics and large magnet levitation force. The single domain REBa2Cu3O7–δ (REBCO) superconductors have the wide and potential applications in the high-tech fields, such as micro-magnet superconducting maglev train, superconducting motor and superconducting magnetic separation system. However, a large number of multi-domain samples are easy to produce in the preparation process, which leads the success rate to decrease significantly and the cost to increase considerably, which restricts its practical application process. Inspired by the top seeded infiltration growth method, we develop a reliable method of recycling failed GdBCO sample by re-supplementing the liquid phase lost in the primary growth process and pretreating the failed sample as solid phase source billets. We recycle a series of GdBCO samples by using this new technique successfully. The growth morphology, superconducting properties, and microstructures of the recycled GdBCO bulk superconductors are investigated in detail in this study. The results show that the magnetic levitation forces of the recycled GdBCO samples are all greater than 30 N, their magnetic flux densities are all above 0.3 T, and their capture efficiencies are above 60%. These results provide the scientific basis and new ideas for developing the low cost and high efficient yield of fabrication of the REBCO bulk superconductors.
Sound field enhancement based on multiple-cavity metamaterial
Authors: Wang Hao-Ran , Lan Jun , Chen Jia-Hui , Li Yi-Feng ,   College of Computer Science and Technology, Nanjing Tech University, Nanjing 211800, China,   Key Laboratory of Modern Acoustics, Ministry of Education, Institute of Acoustics, Nanjing University, Nanjing 210093, China
Published: June 2021

Owing to the low energy density of sound energy in nature, it is difficult to realize the local enhancement effect of sound field in air. Therefore, it is of great significance to explore new physical mechanisms and methods to achieve sound field enhancement. In recent years, artificial Mie resonance structure as a kind of acoustic metamaterial has attracted considerable attention, which has a variety of resonant modes, such as monopolar, dipolar, quadrupolar and higher multipolar modes. Compared with local resonance, acoustic Mie resonance mode has strong acoustic interaction, which can effectively enhance the acoustic field by the coupling of the Mie resonance. In this paper, we design an acoustic metamaterial composed of multiple-cavity unit cells, which is capable of realizing sound field enhancement. The multiple-cavity unit is circular in external shape and it is composed of a circular central cavity and twelve resonators. The twelve resonators are evenly distributed around the circular central cavity, with three resonators combined into a group. This exotic function arises from the compound monopole Mie resonance introduced by mutual coupling between the system structure and the monopole Mie resonance of each unit cell. Symmetric and asymmetric metamaterials are constructed by arranging several multiple-cavity unit cells in different forms. These two kinds of metamaterials can be used to achieve sound field enhancement with different effects. The results show that due to the symmetry of metamaterial structure, the symmetric metamaterials with square, circle, rectangle and regular hexagon shapes can realize the sound field enhancement, which is independent of the direction of incident wave. However, for the asymmetric metamaterial with equilateral triangle shape, the sound intensity in the center of the system varies with incident direction, which indicates that the designed asymmetric metamaterial has a strong dependence on the direction of incident wave. These two kinds of metamaterials constructed in this research can possess a number of potential applications such as in sound insulation, acoustic sensor, noise location, acoustic communication and asymmetric acoustic device. These two kinds of metamaterials constructed in this research can possess a number of potential applications such as in sound insulation.
Molecular dynamics simulation of Brownian diffusion boundary condition for nanoparticles
Authors: Ma Ao-Jie , Chen Song-Jia , Li Yu-Xiu , Chen Ying ,   School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China
Published: June 2021

Brownian motion refers to the endless random motion of nanometer-to-micron particles suspended in a fluid. It widely exists in nature, and is applied to energy, biology, chemical industry, environment and other industries. As the Brownian motion of the object decreases from the micron level to the nanometer level, the boundary conditions of the particle motion no longer strictly follow the stick hydrodynamic boundary conditions, but are closer to the slip boundary theory, meanwhile, the interaction between particles and solvents has increasingly important influence on particle dynamics. Molecular dynamics simulation is an important means to study nanofluids, which can not only capture the microscopic details of the interactions between particles and solvent molecules in nanofluids, but also have high potential function accuracy. In this paper, an all-atom model of the diffusion of Cu nanoparticles of different sizes in water is established by using the rigid TIP4P/2005 water molecule model as solvent, the dynamic viscosity from the TIP4P/2005 model is in good agreement with the experimental result, which is verified by the Green-Kubo formula. The FCC lattice structure is used to construct Cu particles of 0.5 nm, 1.0 nm, 1.5 nm, 2.0 nm in size, and the interaction between atoms in the particle is described by the EAM potential. The translational diffusion coefficient of particles is fitted by the single particle tracking algorithm and the least square method, the rotational diffusion coefficient of particles is obtained by quaternion transformation. The diffusion coefficient and friction factor of the particles are calculated, and the friction factor is compared with the result under the stick hydrodynamics boundary conditions and the result under the slip boundary conditions. It is found that the frictional factors of translation and rotation of nano-particles lie between the theoretical values predicted by the two boundary conditions. The radial distribution functions of water molecules around nanoparticles of different sizes are calculated, we find that the smaller the particle size, the more obvious the adsorption of solvent molecules will be, and the water molecular layer on the particle surface will increase the effective volume of particles and make the calculation result of friction factor larger. The effect of solvent adsorption on the effective hydrodynamic radius of particles cannot be ignored when calculating the friction coefficient of Brownian motion of nano-particles, especially when the particle radius is close to the solvent radius. In Brownian dynamics, viscous resistance and stochastic force are constrained by fluctuation dissipation theorem, and a reasonable selection of particle friction factor can provide theoretical basis for the improvement of Brownian dynamics.
Influence of directional infrared irradiations on the temperature field in ICF cryotargets
Authors: Guo Fu-Cheng , Li Cui , Li Yan-Zhong ,   School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: June 2021

For an inertial-confinement-fusion cryogenic target, the fusion ice layer inside the capsule should have a uniformity more than 99% and an inner surface roughness less than 1 μm (root mean square) to avoid Rayleigh-Taylor instabilities. And this highly smooth ice layer required for ignition is generated at the presence of volumetric heat and affected by the thermal environment around the capsule. For the D2 fuel targets, the volumetrically heating can be supplied by exposing the ice layer to IR radiation. A major challenge of IR-layering is a spherically uniform IR illumination of the capsule, particularly for capsules held in cylindrical hohlraums in indirect-drive targets. In the present study, a numerical study is conducted on the thermal environment of D2 fuel capsule under directional infrared radiation. A 3D simulation model coupling the photonic and thermal fields has been established based on the Monte Carlo ray tracing method. The influence of infrared optical fibers’ layouts and source power intensity on temperature characteristics outside the capsule have been studied. The results indicate that at constant total power of optical fibers, the more optical fibers set up, the lower the average temperature of the outer surface decreases, and the more uniform the capsule outer surface temperature turns to be. The temperature uniformity of capsule outer surface deteriorates with the two or less optical fibers, but improves with the number greater than 2 in which case ΔTmax and ΔTw can decrease by 61.94% and 76.33% at most. A proper offset of optical fiber spots towards the hohlraum poles can improve the temperature uniformity of capsule outer surface, while the other two optical fiber spot offset schemes deteriorate the temperature uniformity. The results are of guiding significance for determining the optical fibers layout in experiment and further design option for cryogenic targets.
Sensing characteristics of dual band terahertz metamaterial absorber sensor
Authors: Pang Hui-Zhong , Wang Xin , Wang Jun-Lin , Wang Zong-Li , Liu Su-Yalatu , Tian Hu-Qiang ,   College of Electronic Information Engineering, Inner Mongolia University, Hohhot 010021, China
Published: June 2021

The terahertz metamaterial absorber sensor is an important functional device of the metamaterials. It can realize not only the perfect absorption in the incident terahertz wave, but also the detect sample by monitoring the deviation of the absorption frequency of the metamaterial absorber sensor.

Dual-band metamaterial absorber sensor has double frequency resonance peak. By matching the characteristic frequency between the sensor and the substance to be measured, the information reflecting the difference of the substance to be measured is increased, to improve the accuracy and sensitivity of material detection. Compared with the traditional metamaterial absorber sensor, the dual-band metamaterial absorber sensor can realize very accurate sensing and detection function through multi-point matching of information.

In this paper, a double band terahertz band metamaterial absorber sensor is proposed. The absorption rate of the metamaterial absorber sensor reaches over 99% at 0.387 THz and 0.694 THz frequency point, achieving “perfect absorption”. Through the analysis of a series of materials with different refractive indices to be measured, the suitable sensing range of the designed terahertz metamaterial absorber sensor is obtained. By analyzing the different thickness of the substance to be measured and the different medium layer materials, the thickness of the substance to be measured and the medium layer materials which can improve the sensing performance of the sensor are obtained. In this paper, the sensing identification of edible oil is taken for example to verify that the dual-band terahertz metamaterial absorber sensor designed in this paper can realize high sensitivity and rapid detection, and has a broad development prospect in the field of sensing and detection.
Optical conductivity of twisted bilayer graphene under heterostrain
Authors: Cai Xiao-Xiao , Luo Guo-Yu , Li Zhi-Qiang , He Yan ,   College of Physics, Sichuan University, Chengdu 610065, China
Published: June 2021

Twisted bilayer graphene (TBG) is a two-dimensional material composed of two layers stacked at a certain angle. When the twisted angle decreases, the lattice mismatch between two layers produces moiré pattern at a long wavelength which significantly modifies the low-energy band structure. In particular, when the twisted angle is close to the so-called “magic angle”, two moiré flat bands are formed near a charge neutral point due to the strong interlayer coupling. These flat bands with high density of states are essential in realizing superconductivity and correlated insulating states. More recently, the magic angle TBG combining an hBN system has exhibited spin-valley polarization when 3/4 of flat bands are filled, thereby providing an ideal platform to achieve quantum anomalous Hall states. Whether it is TBG system or TBG-hBN system, the flat band becomes a crucial condition for discovering so rich physical connotations. Besides the twisted angle, the strain gives an alternative way to modulate flat bands. It has been reported that applying heterostrain in magic angle TBG can makes flat moiré band tunable; strain can also generate flat bands in non-magic angle TBG. Moreover, the reconstruction of TBG due to the strain gives rise to a serial of novel physical phenomena such as topological protected soliton and photonic crystal. Another reason for studying strain effect is that the strain is ubiquitous in the fabrication progress. The strain can also be controlled via piezoelectric substrate which makes possible the in situ modulation of correlated states, topology and quantum effect.

Our work is to study the heterostrain effect in TBG band structure and optical conductivity by using a continuum model. Although the resulting conduction band and valence bands keep connected through Dirac points protected by the C2 symmetry, their separation increases significantly when heterostrain is applied while the Dirac point is also shifted. The optical conductivity is characterized by a series of peaks associated with van Hove singularities, and the peak energies are systematically shifted with the strain amplitude. These changes show that the heterostrain exerts a great influence on electron property of TBG.
Image alignment for synchrotron radiation based X-ray nano-CT
Authors: Su Bo , Tao Fen , Li Ke , Du Guo-Hao , Zhang Ling , Li Zhong-Liang , Deng Biao , Xie Hong-Lan , Xiao Ti-Qiao ,   Shanghai Institute of Applied Physics, China Academy of Sciences, Shanghai 201800, China,   University of Chinese Academy of Sciences, Beijing 100084, China,   Shanghai Synchrotron Radiation Facility/Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
Published: June 2021

Synchrotron radiation-based X-ray nano-imaging is a powerful tool for non-destructively studying the internal nano-scale structure of matter. Here in this paper, we review the state-of-the-art image alignment technology in the field of nano-resolution imaging, and classify and analyze the technology according to the research stage. First, through the publications of image alignment algorithm, the development direction of future research is analyzed. Then, the most effective image alignment application in the field of nano imaging based on classic image alignment algorithms is summarized. The paper also presents the feature detection operators that are useful for nano-scale image registration selected from recent feature detection research, which has important guiding significance for the specific application and optimization of nano-imaging image registration. Finally, the state-of-the-art image registration method based on deep learning is introduced, the applicability and potential of deep learning in nano-imaging registration technology are discussed, and future research directions and challenges are prospected based on different neural network characteristics.
Active illumination uniformity with narrow spectrum laser based on ladderlike phase modulation
Authors: Luo Wen , Chen Tian-Jiang , Zhang Fei-Zhou , Zhou Kai , An Jian-Zhu , Zhang Jian-Zhu ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China,   Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China,   Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China,   Graduate School of China Academy of Engineering Physics, Beijing 100088, China
Published: June 2021

Active illumination is a crucial technology for active imaging, active tracking and aiming system. But the atmosphere turbulence distributed over the entire path causes the intensity to fluctuate, which reduces the illumination uniformity seriously. Therefore, it is desirable to find ways to reduce the intensity fluctuation and improve the uniformity of active illumination. It has been revealed that one can improve illumination uniformity by using multi-beam laser illuminator. Another effective approach is partially coherent beam illumination.

In this paper, a novel method is suggested to improve the illumination uniformity. Phase disturbance is induced by a ladder-like phase modulator (LPM) and the transmitting field of narrow spectrum laser is confused, and thus the atmosphere turbulence will be compensated and the illumination uniformity will be improved. The physical models of narrow spectrum laser phase modulation and atmosphere propagation are deduced, and the expression of the facular distribution is obtained. The active-illumination experimental setup with a laser propagation distance of 1.8 km through horizontal atmosphere is established. Based on the facular distribution of illumination laser at 1.8 km, the uniformity and stabilization are achieved. The experimental results indicate that the illumination uniformity and stabilization are both improved. The spatial and central time scintillation indexes are improved from 0.73 to 0.33 and from 0.38 to 0.14, respectively.
Laser-diode-array side-zigzag-pumped polygon thin-disk laser
Authors: Chen Qiao , Qiu Ji-Si , Zhang Xu , Ge Wen-Qi , Liu Yue-Liang , Liu Hao , Wang Hao-Cheng ,   Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China,   School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China,   School of Physics Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Published: June 2021

The high-average-power diode-pumped solid-state laser is one of the main research directions in the field of international laser technology, and has major applications in the fields like space exploration, precise detection, fusion research, etc. Under high-power pumping conditions, the conventional rods or slabs are not conducive to effectively removing waste heat. And the thermal effect causes the quality of the laser beam to deteriorate, which limits the further increase of the output power. In this article, the polygonal Nd: YAG thin disk is taken as a gain medium for the laser, and experiments verify that the side pumping method can obtain a higher output power of the all-solid-state pulsed laser while ensuring high beam quality. The gain medium is a regular pentagonal Nd: YAG thin disk with a side-cut-angle of 45°, the crystal thickness is 1.5 mm, and the diameter of the inscribed circle on the front face is 16 mm. Five laser diode arrays are placed symmetrically around the disk, and the pump surfaces are parallel to the sides of the disk. The pump laser propagates along the zigzag path between the upper and lower surface of the disk, thus improving the absorptive efficiency and pump uniformity. Through the optimization study of its gain characteristics and optical characteristics, the high-efficiency high-uniform pumping is achieved. Along the pump light coupling transmission path, the fast-axis collimator is used to control the beams in the fast-axis direction to be nearly parallel, and the large-area pump light is compressed through the coupling structure of cylindrical lens and light guide to match the size of the thin disk, and the pump coupling efficiency measured experimentally is 97%. When the Nd3+ doping concentration in the crystal is 0.3 at.%, the gain medium absorptive efficiency is 87%, and the root mea squared pump absorptive distribution uniformity in the gain medium is 3.21%. The fluorescence distribution of the gain medium is in good agreement with the simulated data. When the pump energy is 2.2 J, a laser output with an energy of 0.85 J is obtained, and optical-to-optical efficiency and slope efficiency are 38.8% and 40.1%, respectively. The single pulse energy stability is 2.7%(RMS) at 1 Hz frequency. In the stable cavity, the beam quality β - factor is measured to be about 10.
Multi-objective optimization of ship magnetic field modeling method
Authors: Dai Zhong-Hua , Zhou Sui-Hua , Zhang Xiao-Bing ,   Department of Weaponry Engineering, Naval University of Engineering, Wuhan 430033, China
Published: June 2021

Ship magnetic field modeling is not only beneficial to understanding the characteristics of ship magnetic field, but also can predict the space distribution of ship magnetic field, which has an important application in ship protection and underwater weapons. Aiming at the problems of low modeling accuracy and poor stability in establishing the ship magnetic field hybrid model, a method of establishing a high precision stablity model is proposed in this paper. A hybrid model of magnetic field of a ship is established by using a uniformly magnetized rotating ellipsoid and a magnetic dipole array. Since the number and positions of magnetic dipoles in the hybrid model have an important effect on the modeling accuracy and stability, the fitting error function representing the modeling accuracy and the coefficient matrix condition number function representing the stability of the model are constructed by taking the magnetic dipole parameters as unknown variables. The multi-objective function is constructed by combining the fitting error function with the coefficient matrix conditional number function, which indirectly transforms the modeling problem into a multi-objective optimization problem. The multi-objective function is solved by using the multi-objective particle swarm optimization algorithm, and an optional set of modeling solution results is obtained. In order to select the best results from the optional set, the corresponding selection rules are designed based on the modeling accuracy. The proposed method is validated by the measured data of three kinds of ship models, the modeling results show that the relative error of the model is less than 3%, and the conversion error is less than 6%, which verifies that the proposed method can effectively model the ship magnetic field. Though the measurement data error exists, the modeling solution results from the proposed method have the best stability, which verifies that the modeling method proposed in this work has good stability. Compared with the two existing modeling methods, the proposed method has very good modeling accuracy and stability. Finally, the actual data of a ship on the sea are used for modeling, and the modeling results further verify that the proposed method has high modeling accuracy and conversion accuracy, and can be effectively applied to the relevant projects.
High-efficiency polarization-insensitive superconducting nanowire single photon detector
Authors: Zhang Wen-Ying , Hu Peng , Xiao You , Li Hao , You Li-Xing ,   State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China,   Center for Excellence in Superconducting Electronics, Chinese Academy of Sciences, Shanghai 200050, China,   University of Chinese Academy of Sciences, Beijing 100039, China,   Key Laboratory of Space Active Opto-electronics Technology, Chinese Academy of Sciences, Shanghai 200050, China
Published: June 2021

Superconducting nanowire single photon detector (SNSPD) has been widely used in many fields such as quantum communication due to its extremely high detection efficiency, low dark count rate, high count rate, and low timing jitter. Compared with conventional single-photon detectors with planar structure, SNSPD is typically made a periodical meandering structure consisting of parallel straight nanowires. However, owing to its unique linear structure, the detection efficiency of SNSPD is dependent on the polarization state of incident light, thus limiting SNSPD’s applications in unconventional fiber links or other incoherent light detection. In this paper, a polarization-insensitive SNSPD with high detection efficiency is proposed based on the traditional meandering nanowire structure. A thin silicon film with a high refractive index is introduced as a cladding layer of nanowires to reduce the dielectric mismatch between the nanowire and its surroundings, thereby improving the optical absorption efficiency of nanowires to the transverse-magnetic (TM) polarized incident light. The cladding layer is designed as a sinusoidal-shaped grating structure to minimize the difference in optical absorption efficiency between the transverse electric (TE) polarized incident light and the TM polarized incident light in a wide wavelength range. In addition, the twin-layer nanowire structure and the dielectric mirror are used to improve the optical absorption efficiency of the device. Our simulation results show that with the optimal parameters, the optical absorption efficiency of nanowires to both of the TE polarized incident light and TM polarized incident light has a maximum of over 90% at 1550 nm, and the corresponding polarization extinction ratio is less than 1.22. The fabricated device possesses a maximum detection efficiency of 87% at 1605 nm and a polarization extinction ratio of 1.06. The measured detection efficiency exceeds 50% with a polarization extinction ratio less than 1.2 in a wavelength range from 1505 nm to 1630 nm. This work provides a reference for high-efficiency polarization-insensitive SNSPD in the future.
Transport process and energy loss of heavy ions in silicon carbide
Authors: Zhang Hong , Guo Hong-Xia , Pan Xiao-Yu , Lei Zhi-Feng , Zhang Feng-Qi , Gu Zhao-Qiao , Liu Yi-Tian , Ju An-An , Ouyang Xiao-Ping ,   School of Material Science and Engineering, Xiangtan University, Xiangtan 411105, China,   Northwest Institute of Nuclear Technology, Xi’an 710024, China,   State Key Laboratory of Science and Technology on Reliability Physics and Application of Electronic Component, CEPREI, Guangzhou 510610 China
Published: June 2021

Using the Monte Carlo method, the energy losses in silicon carbide of heavy ions with different linear energy transfers (LETs) are simulated and calculated. The simulation results show that the energy loss per unit depth of heavy ions in silicon carbide is affected by both the ion energy and the incident depth. Primary heavy ions and secondary electrons mainly cause energy loss, and the non-ionization energy loss only accounts for about 1% of the total energy loss. With the increase of LET, the initial angle and energy distribution of the secondary electrons become more and more concentrated. The peak position of the generated charge deposition is in the center of the heavy-ion track, and the distribution is linearly decreasing in Gaussian form in the direction perpendicular to the incident depth. In the californium source experiment of SiC MOSFET, when the drain voltage is 480 V, the device has a single event burnout, and the breakdown voltage of SiC MOSFET is less than 1 V after burnout has occurred. With the experimental results, we carry out the TCAD simulation of SiC MOSFET and obtain the electric field distribution inside the device under different drain voltages. The electric field parameters are used in the Monte Carlo simulation of SiC MOSFET with considering the metal layer. It is found in the Monte Carlo simulation that the greater the electric field of the epitaxial layer, the longer the path of heavy ions moving on the epitaxial layer is and the more the deposited energy, and that the secondary electrons are more likely to move in the direction of the electric field as the electric field increases, resulting in excessive energy deposition in local areas.
Optimization of the image acquisition procedure in low-field MRI for non-destructive analysis of loin using predictive models
Authors: Caballero Daniel , Pérez-Palacios Trinidad , Caro Andrés , Ávila Mar , Antequera Teresa
Published: June 2021

The use of low-field magnetic resonance imaging (LF-MRI) scanners has increased in recent years. The low economic cost in comparison to high-field (HF-MRI) scanners and the ease of maintenance make this type of scanner the best choice for nonmedical purposes. However, LF-MRI scanners produce low-quality images, which encourages the identification of optimization procedures to generate the best possible images. In this paper, optimization of the image acquisition procedure for an LF-MRI scanner is presented, and predictive models are developed. The MRI acquisition procedure was optimized to determine the physicochemical characteristics of pork loin in a nondestructive way using MRI, feature extraction algorithms and data processing methods. The most critical parameters (relaxation times, repetition time, and echo time) of the LF-MRI scanner were optimized, presenting a procedure that could be easily reproduced in other environments or for other purposes. In addition, two feature extraction algorithms (gray level co-occurrence matrix (GLCM) and one point fractal texture algorithm (OPFTA)) were evaluated. The optimization procedure was validated by using several evaluation metrics, achieving reliable and accurate results (r > 0.85; weighted absolute percentage error (WAPE) lower than 0.1%; root mean square error of prediction (RMSEP) lower than 0.1%; true standard deviation (TSTD) lower than 2; and mean absolute error (MAE) lower than 2). These results support the high degree of feasibility and accuracy of the optimized procedure of LF-MRI acquisition. No other papers present a procedure to optimize the image acquisition process in LF-MRI. Eventually, the optimization procedure could be applied to other LF-MRI systems.