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Tightly focused properties of a partially coherent radially polarized power-exponent-phase vortex beam

Chinese Physics B 2023年第2期32卷 303-310页

作者：陈康马志远胡友友 Department of Optoelectronic Information of Science and Engineering School of ScienceJiangsu University of Science and TechnologyZhenjiang 212100China Applied Optics Research Center Jiangsu University of Science and TechnologyZhenjiang 212100China

A partially coherent beam called a radially polarized multi-Gaussian Schell-model power-exponent-phase vortex beam is introduced. Both the analytical formula of the beam propagating through the high-numerical-aperture objective lens based on the vectorial diffraction theory, and the cross-spectral density matrix of the beam in the focal region are derived. Then,the tight focusing characteristics of the partially coherent radially polarized power-exponent-phase vortex beam are studied numerically, and the intensity distribution, degree of polarization and coherence of the beams in the focusing region with different topological charge, power order, beam index and coherence width are analyzed in detail. The results show that the contour of the spot becomes clearer and smoother with the increase in the beam index, and the focal fields of different structures that include the flattened beam can be obtained by changing the coherence width. In addition, by changing the topological charge and power order, the intensity can gather to a point along the ring. These unique properties will have potential applications in particle capture and manipulation, especially in the manipulation of irregular particles.

关键词： partially coherent beam power-exponent-phase vortex beam tight focusing properties

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Ferromagnetic state with large magnetic moments realized in epitaxially strained Sr3Ru2O7 films

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Physical Review B 2024年第12期109卷 L121113-L121113页

作者： Ren Oshima Tatsuto Hatanaka Shinichi Nishihaya Takuya Nomoto Markus Kriener Takahiro C. Fujita Masashi Kawasaki Ryotaro Arita Masaki Uchida Department of Physics Tokyo Institute of Technology Tokyo 152-8551 Japan Research Center for Advanced Science and Technology the University of Tokyo Tokyo 153-8904 Japan RIKEN Center for Emergent Matter Science (CEMS) Wako 351-0198 Japan Department of Applied Physics the University of Tokyo Tokyo 113-8656 Japan

Technical advancements in oxide molecular beam epitaxy (MBE) have opened new avenues for studying various quantum transport phenomena in correlated transition-metal oxides, as exemplified by the exotic superconductivity of Sr2RuO4 and quantum oscillations of SrRuO3. On the other hand, film research of another Ruddlesden-Popper strontium ruthenate Sr3Ru2O7, which exhibits a unique quantum phase related to metamagnetism in bulk systems, has not progressed well. Here, we report the fabrication of high-quality Sr3Ru2O7 thin films by oxide MBE and the observation of a strain-induced ferromagnetic ground state. The change in magnetic exchange coupling evaluated by first-principles calculations indicates a systematic relation between the compression of the c-axis length and induced ferromagnetism. Giant epitaxial strain in high-quality films will be a key to a comprehensive understanding of the magnetism in Ruddlesden-Popper strontium ruthenates Srn+1RunO3n+1, which sensitively depends on the ratio of in-plane to out-of-plane Ru-Ru distances.

关键词： Epitaxial strain Ruthenates First-principles calculations Molecular beam epitaxy

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Optical Fiber Hydrogen Sensor Based onπ-Phase-Shifted Grating and Sputtered Pd/Hf Composite Film

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Photonic Sensors 2025年第2期15卷 34-44页

作者： Fan ZHANG Fabian BUCHFELLNER Wenbin HU Wenxin AO Qiang BIAN Johannes ROTHS Minghong YANG National Engineering Research Center for Optical Fiber Sensing Technology and Network Wuhan 430070China Photonics Lab Munich University of Applied ScienceMunich 80335Germany

A novel optical fiber hydrogen sensor based on theπ-phase-shifted grating and partial coated Pd/Hf composite film is proposed and experimentally demonstrated in this *** hydrogen sensitive Pd/Hf film with the length of 4 mm is successfully deposited in theπ-phase-shifted grating region by the magnetron sputtering process and rotating fixture *** the hydrogen sensitivity between the notch and flank wavelengths of theπ-phase-shifted grating is different due to the partial coating only on theπ-phase-shifted grating region,the relative shift between the notch and flank wavelengths is employed to characterize the hydrogen concentration in this *** hydrogen calibration results show that the sensor shows the good response and *** the temperature of 20 and℃the hydrogen concentration of 2%,the wavelength distance shifts of 200 nm and 500 nm Pd/Hf coatings are 12.6 pm and 33.5 pm,respectively.

关键词： Fiber-optic hydrogen sensor Pd/Hf composite film π-phase-shifted grating magnetron sputtering temperature decoupling

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CsPbI_(2)Br epitaxial shell for efficient PbS quantum dot solar cells

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Nano research 2024年第12期17卷 10302-10308页

作者： Sami Ur Rahman Yong-Hui Song Zhen-Yu Ma Xiao-Lin Tai Bai-Sheng Zhu Yi-Chen Yin Li-Zhe Feng Jing-Ming Hao Guan-Jie Ding Kuang-Hui Song Ya-Lan Hu Tieqiang Li Jixian Xu Hong-Bin Yao Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Department of Applied Chemistry University of Science and Technology of ChinaHefei 230026China Department of Material Science and Engineering University of Science and Technology of ChinaHefei 230026China

Lead sulfide quantum dots(PbS QDs)are promising candidates for high-performance solar cells due to their tunable bandgaps and low-cost solution ***,low carrier mobility and numerous surface defects restrict the performance of the fabricated solar ***,we report the synthesis of novel PbS-perovskite core-shell QDs to solve the low carrier mobility problem of PbS QDs via a facile hot injection ***_(2)Br shell enabled strain-free epitaxial growth on the surface of PbS QDs because of 98%lattice *** results demonstrate a significant improvement in the photoluminescence and stability of the synthesized PbS-CsPbI_(2)Br QDs upon shell formation,attributed to the effective suppression of surface defects by the epitaxial shell of CsPbI_(2)*** a result,the obtained solar cell based on PbS-CsPbI_(2)Br core-shell QD exhibits a power conversion efficiency(PCE)of 8.43%,two times higher than that of pristine PbS ***,the construction of PbS-CsPbI_(2)Br core-shell structures represent a promising strategy for advancing the performance of PbS QDs-based optoelectronic devices.

关键词： lead chalcogenide perovskites core-shell epitaxial growth solar cell

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Boosting high-rate Li-ion storage properties by La(Ⅲ)ion doping in spinel(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)high-entropy oxide anode

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Journal of advanced Ceramics 2024年第6期13卷 769-779页

作者： Shijie Chen Mengfan Bao Yanggang Jia Pengpeng Wang Dan Wei Yuhuan Guo Jie Tan Aiqin Mao Advanced Ceramics Research Center School of Materials Science and EngineeringAnhui University of TechnologyMa’anshan 243032China Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials(Anhui University of Technology) Ministry of EducationMa’anshan 243032China

The present work aims to create lattice distortion and optimize the surface oxygen vacancy(OV)concentration in a model spinel(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)high-entropy oxide(HEO)through a heteroatom La^(3+)doping *** demonstrated,La^(3+)with a large radius can be doped successfully into the spinel lattice of(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4),thereby not only causing lattice distortion to increase oxygen vacancies but also refining crystalline grains and improving the specific *** with the(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)anode,the(La_(0.01)CoCrFeMnNi)_(3/5.01)O_(4) anode with moderate doping exhibits excellent cycling performance(1228 mAh·g^(−1)after 400 cycles at 0.2 A·g^(−1))and yields an increase of 75%rate capability at 3 A·g^(−1)(420 mAh·g^(−1)at 3 A·g^(−1)).The desirable kinetic transport of electrons and diffusion of Li+within the moderately La^(3+)-doped anode and the synergistic interfacial pseudocapacitive behavior satisfy the redox reaction at a high rate,thus increasing rate capability.

关键词： lithium-ion battery(LIB) anode lattice distortion high-entropy oxide(HEO) high-rate performance La^(3+)doping oxygen vacancy(OV)

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Elemental segregation, microstructure, and mechanical properties of TMCP-treated high-manganese wear-resistant steel

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Journal of Iron and Steel research International 2025年第3期32卷 783-798页

作者： Yang He Jian-hua Liu Guan-yong Huang Hao Xu Ning Liu Jiang-hua Qi National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing100083China Technology Center of Hunan Valin Lianyuan Iron and Steel Co. Ltd.Loudi417009HunanChina

The elemental segregation,microstructure,and mechanical properties of thermo-mechanical control process(TMCP)treated high-manganese wear-resistant steel(HMWS)were experimentally ***,the initial elemental segregation in the continuous casting slab of HMWS was characterized using the original position *** results showed that the elemental segregation predominantly occurred near the quarter and the center regions of the *** homogenization of manganese(Mn)in the slab was not as obvious as that of other elements after the heating ***,a series of hot-rolling tests were carried out on HMWS slab samples under different TMCP conditions,and the elemental segregation and microstructure of the TMCP-treated HMWS were investigated by microscopic analysis *** findings demonstrated that the segregations of carbon and silicon were effectively eliminated after the TMCP treatment,while Mn segregation presented a band-shaped arrangement and could be reduced at lower finishing rolling *** matrix phase of HMWS remained austenite regardless of the TMCP conditions,and the average size of austenite grains increased with the increasing finishing rolling *** particles were observed to form within austenite grains and even along grain boundaries at higher coiling ***,the mechanical tests were performed on the TMCP-treated HMWS at room *** mechanical properties including tensile stress,yield stress,Charpy impact energy,and microhardness were discussed considering the effects of Mn segregation band,microstructure,and carbide precipitation.

关键词： High-manganese wear-resistant steel Thermo-mechanical control process Manganese segregation Microstructure Mechanical property

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A grasp planning algorithm under uneven contact point distribution scenario for space non-cooperative target capture

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Chinese Journal of Aeronautics 2023年第11期36卷 452-464页

作者： Bicheng CAI Chengfei YUE Fan WU Xueqin CHEN Yunhai GENG Research Center of the Satellite Technology Harbin Institute of TechnologyHarbin 150001China Institute of Space Science and Applied Technology Harbin Institute of Technology ShenzhenShenzhen 518055China

The contact point configuration should be carefully chosen to ensure a stable capture,especially for the non-cooperative target capture mission using multi-armed *** this work scenario,the contact points on the base and on the arms are distributed on the opposite side of the ***,large forces will be *** cope with this problem,an uneven-oriented distribution union criterion is *** union criterion contains a virtual symmetrical criterion and a geometry *** virtual symmetrical contact point criterion is derived from the proof of the force closure principle using computational geometry to ensure a stable grasp,and the geometry criterion is calculated by the volume of the minimum polyhedron formed by the contact points to get a wide-range *** further accelerate the optimization rate and enhance the global search ability,a line array modeling method and a continuous-discrete global search algorithm are *** line array modeling method reduces the workload of calculating the descent direction and the gradient available,while the continuous-discrete global search algorithm reducing the optimization *** a highly efficient grasping is achieved and the corresponding contact point is ***,an exhaustive verification is conducted to numerically analyze the disturbance resistance ability,and simulation results demonstrate the effectiveness of the proposed algorithms.

关键词： Grasp planning Line array modeling Space debris removal Space non-cooperative target capture Virtual symmetrical contact point method

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WavEnhancer: Unifying Wavelet and Transformer for Image Enhancement

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Journal of Computer science & technology 2024年第2期39卷 336-345页

作者：李梓诺陈绪行郭淑娜王书强潘治文 Department of Computer and Information Science University of MacaoMacao 999078China Research Center for Biomedical Information Technology Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Image enhancement is a widely used technique in digital image processing that aims to improve image aesthetics and visual quality. However, traditional methods of enhancement based on pixel-level or global-level modifications have limited effectiveness. Recently, as learning-based techniques gain popularity, various studies are now focusing on utilizing networks for image enhancement. However, these techniques often fail to optimize image frequency domains. This study addresses this gap by introducing a transformer-based model for improving images in the wavelet domain. The proposed model refines various frequency bands of an image and prioritizes local details and high-level features. Consequently, the proposed technique produces superior enhancement results. The proposed model’s performance was assessed through comprehensive benchmark evaluations, and the results suggest it outperforms the state-of-the-art techniques.

关键词： transformer wavelet transform image enhancement

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Hierarchical path planning for multi-arm spacecraft with general translational and rotational locomotion mode

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science China(Technological sciences) 2023年第4期66卷 1180-1191页

作者： YUE ChengFei LIN Tao ZHANG Xiao CHEN XueQin CAO XiBin Institute of Space Science and Applied Technology Harbin Institute of Technology ShenzhenShenzhen 518055China Research Center of the Satellite Technology Harbin Institute of TechnologyHarbin 150001China

On-orbit construction and maintenance technology will play a significant role in future space *** dexterous multifunctional spacecraft equipped with multi-arm,for instance,Spider Fab Bot,has attracted a great deal of focus due to its versatility in completing these *** such engineering practice,point-to-point moving in a complex environment is the fundamental *** paper investigates the three-dimensional point-to-point path planning problem,and a hierarchical path planning architecture is developed to give the trajectory of the multi-arm spacecraft effectively and *** the proposed 3-level architecture,the high-level planner generates the global constrained centric trajectory of the spacecraft with a rigid envelop assumption;the middle-level planner contributes the action sequence,a combination of the newly developed general translational and rotational locomotion mode,to cope with the relative position and attitude of the arms about the centroid of the spacecraft;the low-level planner maps the position/attitude of the end-effector of each arm from the operational space to the joint space ***,the simulation experiment is carried out,and the results verify the effectiveness of the proposed three-layer architecture path planning strategy.

关键词： multi-arm spacecraft path planning hierarchical architecture locomotion mode translational locomotion rotational locomotion

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Tuning mechanical and electrical performances of B_(4)C-TiB_(2)ceramics in a two-step spark plasma sintering process

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Journal of advanced Ceramics 2024年第4期13卷 518-528页

作者： Jun Zhao Xingshuo Zhang Zongning Ma Dong Wang Xing Jin Songlin Ran Advanced Ceramics Research Center School of Materials Science and EngineeringAnhui University of TechnologyMaanshan 243002China Anhui Engineering Research Center for High Efficiency Intelligent Photovoltaic Module Chaohu UniversityHefei 238024China

B_(4)C–TiB_(2)is an advanced electrically conductive ceramic with excellent mechanical and electrical discharge machinable *** is challenging and rewarding to achieve highly conductive and hard B_(4)C–TiB_(2)composites at a minimum content of conductive TiB2 that has inferior hardness but double specific gravity of the B_(4)C matrix.A novel strategy was used to construct conductive networks in B_(4)C‒15 vol%TiB2 composite ceramics with B_(4)C,TiC,and amorphous B as raw materials by a two-step spark plasma sintering *** influences of particle size matching between B_(4)C and TiC on the conducting of the strategy and the microstructure were discussed based on the selective matrix grain growth *** mechanical and electrical properties were also systematically *** B_(4)C–15 vol%TiB2 composite ceramic prepared from 10.29µm B_(4)C and 0.05µm TiC powders exhibited a perfect three-dimensional interconnected conductive network with a maximum electrical conductivity of 4.25×10^(4)S/m,together with excellent mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 691±58 MPa,30.30±0.61 GPa,and 5.75±0.32 MPa·m^(1/2),respectively,while the composite obtained from 3.12µm B_(4)C and 0.8µm TiC powders had the best mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 827±35 MPa,32.01±0.51 GPa,and 6.45±0.22 MPa·m^(1/2),together with a decent electrical conductivity of 0.65×10^(4)S/m.

关键词： B_(4)C-TiB_(2) mechanical properties electrical conductivity conductive network

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