检索结果-南通市图书馆

Generation of valley pump currents in silicene

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第1期28卷 570-574页

作者： John Tombe Jada Marcellino Mei-Juan wang sa-ke wang Department of Physics Southeast University College of Science Jinling Institute of Technology

We propose a workable scheme for generating a bulk valley pump current in a silicene-based device which consists of two pumping regions characterized by time-dependent strain and staggered potentials, respectively. In a one-dimension model, we show that a pure valley current can be generated, in which the two valley currents have the same magnitude but flow in opposite directions. Besides, the pumped valley current is quantized and maximized when the Fermi energy of the system locates in the bandgap opened by the two pumping potentials. Furthermore, the valley current can be finely controlled by tuning the device parameters. Our results are useful for the development of valleytronic devices based on two-dimensional materials.

关键词： valley currents charge pump quantization silicene

Spin-current pump in silicene

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第5期27卷 500-503页

作者： John Tombe Jada Marcellino Mei-Juan wang sa-ke wang Jun wang Department of Physics Southeast UniversityNanjing 210096China Department of Fundamental Courses Jinling Institute of TechnologyNanjing 211169China

We report a theoretical study of pumped spin currents in a silicene-based pump device,where two time-dependent staggered potentials are introduced through the perpendicular electric fields and a magnetic insulator is considered in between the two pumping potentials to magnetize the Dirac *** is shown that giant spin currents can be generated in the pump device because the pumping can be optimal for each transport mode,the pumping current is *** controlling the relevant parameters of the device,both pure spin currents and fully spin-polarized currents can be *** results may shed a new light on the generation of pumped spin currents in Dirac-electron systems.

关键词： spin currents charge pump quantization silicene

Topological phase in one-dimensional Rashba wire

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第7期25卷 393-400页

作者：汪萨克汪军刘军丰 Department of Physics Southeast University Department of Physics South University of Science and Technology of China

We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.

关键词： one-dimensional topological phase Rashba spin–orbit interaction spatial modulation quantized pump

Theoretical optimization of micropillar arrays for structurally stable bioinspired dry adhesives

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2024年第2期14卷 124-129页

作者： ke Ni Zhengzhi wang Department of Engineering Mechanics School of Civil EngineeringWuhan UniversityWuhan 430072China Wuhan University Shenzhen Research Institute Shenzhen 518108China

Inspired by the excellent adhesion performances of setae structure from organisms,micro/nano-pillar array has become one of the paradigms for adhesive *** micropillar arrays are composed of the resin pillars for adhesion and the substrate with different elastic modulus for *** stress singularity at the bi-material corner between the pillars and the substrate can induce the failure of the micropillar-substrate corner and further hinder the fabrication and application of micropillar arrays,yet the design for the stability of the micropillar array lacks systematical and quantitative *** this work,we develop a semi-analytical method to provide the full expressions for the stress distribution within the bi-material corner combining analytical derivations and numerical *** predictions for the stress within the singularity field can be obtained based on the full expressions of the *** good agreement between the predictions and the FEM results demonstrates the high reliability of our *** adopting the strain energy density factor approach,the stability of the pillar-substrate corner is assessed by predicting the failure at the *** the elastic mismatch between the pillar and substrate given in this paper,the stability can be improved by increasing the ratio of the shear modulus of the substrate to that of the *** study provides accurate predictions for the stress distribution at the bi-material corner and can guide the optimization of material combinations of the pillars and the substrate for more stable bioinspired dry adhesives.

关键词： Micropillar array Stability Bi-material corner Dry adhesive

Quantized bound states around a vortex in anisotropic superconductors

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 146-155页

作者： ke Xiang Da wang Qiang-Hua wang National Laboratory of Solid State Microstructures&School of Physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China

The bound states around a vortex in anisotropic superconductors is a longstanding yet important *** this work,we develop a variational theory on the basis of the Andreev approximation to obtain the energy levels and wave functions of the low-energy quantized bound states in superconductors with anisotropic pairing on arbitrary Fermi *** the case of circular Fermi surface,the effective Schr¨odinger equation yielding the bound state energies gets back to the theory proposed by Volovik and Kopnin many years *** generalization here enables us to prove the equidistant energy spectrum inside a vortex in a broader class of *** importantly,we are now able to obtain the wave functions of these bound states by projecting the quasiclassical wave function on the eigenmodes of the effective Schr¨odinger equation,going beyond the quasiclassical Eilenberger results,which,as we find,are sensitive to the scattering *** the case of isotropic Fermi surface,the spatial profile of the low-energy local density of states is dominated near the vortex center and elongates along the gap antinode directions,in addition to the ubiquitous Friedel oscillation arising from the quantum inteference neglected in the Eilenberger ***,as a consequence of the pairing anisotropy,the quantized wave functions develop a peculiar distribution of winding number,which reduces stepwise towards the vortex *** work provides a flexible way to study the vortex bound states in the future.

关键词： vortex bound state anisotropic superconductor Andreev approximation

Effect of Operation Parameters on the Thermal Characteristics in a Planar Solid Oxide Fuel Cell

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第5期33卷 1974-1989页

作者： wang Mingyuan wang ke wang Yongqing CHEN Jiangshuai AN Bo TU Shantung School of Mechanics and safety Engineering Zhengzhou UniversityZhengzhou 450001China key Laboratory of Process Heat Transfer and Energy saving of Henan Province Zhengzhou UniversityZhengzhou 450002China School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450001China key Laboratory of Pressure Systems and safety(MOE) East China University of Science&TechnologyShanghai 200237China

Effective operation strategies in the solid oxide fuel cell(SOFC)can adjust the spatial distribution of temperature gradient favoring the long-term *** investigate the effects of different operating conditions on the thermal behavior inside SOFC,a three-dimensional model is developed in this *** model is verified by comparing it with the experimental *** heat generation rate and its variation under different operating conditions are *** combined effects of operating voltage and gas temperature are considered to be the key factor influencing the temperature *** to the original case,the temperature of SOFC decreases by 21.4 K when the fuel velocity reaches 5 m/*** the maximum temperature gradient increases by21.2%.Meanwhile,higher fuel velocities can eliminate about 32%of the area with higher temperature *** when the oxidant velocity reaches 7.5 m/s,the peak temperature gradient effectively decreases by 16.59%.Simultaneous adjustment of the oxidant and fuel velocities can effectively reduce the peak temperature gradient and increase the safety *** effects of operation conditions on the temperature gradient of the cell are clarified in this study,which can be a reference for further research on the reliability of SOFCs.

关键词： SOFC heat generation temperature gradient distribution heat source thermal behavior

Transcriptional regulation in the development and dysfunction of neocortical projection neurons

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第2期19卷 246-254页

作者： Ningxin wang Rong Wan ke Tang Precise Genome Engineering Center School of Life SciencesGuangzhou UniversityGuangzhouGuangdong ProvinceChina

Glutamatergic projection neurons generate sophisticated excitatory circuits to integrate and transmit information among different cortical areas,and between the neocortex and other regions of the brain and spinal *** development of cortical projection neurons is regulated by certain essential events such as neural fate determination,proliferation,specification,differentiation,migration,survival,axonogenesis,and *** processes are precisely regulated in a tempo-spatial manner by intrinsic factors,extrinsic signals,and neural *** generation of correct subtypes and precise connections of projection neurons is imperative not only to support the basic cortical functions(such as sensory information integration,motor coordination,and cognition)but also to prevent the onset and progression of neurodevelopmental disorders(such as intellectual disability,autism spectrum disorders,anxiety,and depression).This review mainly focuses on the recent progress of transcriptional regulations on the development and diversity of neocortical projection neurons and the clinical relevance of the failure of transcriptional modulations.

关键词： autism spectrum disorders cognition differentiation excitatory circuits intellectual disability neocortex neurodevelopmental disorders projection neuron specification transcriptional regulation

Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1637-1648页

作者： Guiyun Gao Chenghu wang ke Gao National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing100085China Beijing Engineering Research Center of Earthquake Observation Beijing100085China key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing100085China Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen518055China

The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor ***,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable *** this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests *** shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo ***,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress *** inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress *** stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)*** results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress *** inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints *** M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole.

关键词： Stress tensor Hydraulic tests on pre-existing fractures Mean stress Stress constraint Hydraulic fracturing

Reinforcement Learning-Based Dynamic Order Recommendation for On-Demand Food Delivery

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第2期29卷 356-367页

作者： Xing wang Ling wang Chenxin Dong Hao Ren ke Xing Department of Automation Tsinghua UniversityBeijing 100080China School of Mechanical and Automotive Engineering Qingdao Hengxing University of Science and TechnologyQingdao 266100China Meituan Beijing 100015China

On-demand food delivery(OFD)is gaining more and more popularity in modern *** a kernel order assignment manner in OFD scenario,order recommendation directly influences the delivery efficiency of the platform and the delivery experience of *** paper addresses the dynamism of the order recommendation problem and proposes a reinforcement learning solution *** actor-critic network based on long short term memory(LSTM)unit is designed to deal with the order-grabbing conflict between different ***,three rider sequencing rules are accordingly proposed to match different time steps of the LSTM unit with different *** test the performance of the proposed method,extensive experiments are conducted based on real data from Meituan delivery *** results demonstrate that the proposed reinforcement learning based order recommendation method can significantly increase the number of grabbed orders and reduce the number of order-grabbing conflicts,resulting in better delivery efficiency and experience for the platform and riders.

关键词： on-demand food delivery order recommendation reinforcement learning actor-critic network long short term memory