检索结果-南通市图书馆

Quantum walks advantage on the dihedral group for uniform sampling problem

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2025年第2期77卷 89-100页

作者： Shyam Dhamapurkar Yuhang Dang Saniya Wagh Xiu-Hao Deng Shenzhen institute for Quantum Science and engineering (SIQSE) Southern University of Science and Technology Department of mathematics Tata Institute of Fundamental Research International Quantum Academy (SIQA) Futian District

Random walk algorithms are crucial for sampling and approximation problems in statistical physics and theoretical computer *** mixing property is necessary for Markov chains to approach stationary distributions and is facilitated by *** walks show promise for faster mixing times than classical methods but lack universal proof,especially in finite group ***,we investigate the continuous-time quantum walks on Cayley graphs of the dihedral group D2nfor odd n,generated by the smallest inverse closed symmetric *** present a significant finding that,in contrast to the classical mixing time on these Cayley graphs,which typically takes at least order Ω(n2log（1/2■）),the continuous-time quantum walk mixing time on D2nis of order O(n（log n）5log（1/■）),achieving a quadratic improvement over the classical *** paper advances the general understanding of quantum walk mixing on Cayley graphs,highlighting the improved mixing time achieved by continuous-time quantum walks on *** work has potential applications in algorithms for a class of sampling problems based on non-abelian groups.

关键词： continuous time quantum walks Cayley graphs non-abelian groups mixing time

Self-Triggered Impulsive Control for Nonlinear Stochastic Systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2025年第1期12卷 264-266页

作者： Tao Zhan Yi Ji Yabin Gao Hongyi Li Yuanqing Xia the School of mathematics and Statistics Southwest University the School of Astronautics Harbin Institute of Technology IEEE the College of Electronic and Information engineering Southwest University Zhongyuan University of Technology the School of Automation Beijing Institute of Technology

Dear Editor,This letter deals with the stabilization problem of nonlinear stochastic systems via self-triggered impulsive control(STIC), where the timing of impulsive control actions is not dependent on continuous state monitoring. In contrast to the existing self-triggered control method, novel self-triggered mechanism(STM) is proposed by incorporating a waiting time for stabilizing impulses. This allows for direct prediction of the next impulsive instant.

关键词： Stabilization

Effect of order–disorder transition on thermodynamic and electronic properties of σ and χ phases in W–Re alloy: the first-principles calculation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Tungsten 2025年第1期7卷 195-213页

作者： Zhi-Peng Zhu Dian Jia William Yi Wang Jun-Lei Yin Xing-Yu Gao Shu-Feng Yang Hai-Feng Song Jin-Shan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical University Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics School of Metallurgical and Ecological engineering University of Science and Technology Beijing

The Tungsten-Rhenium(W-Re) alloys,celebrated for their high melting point,strength at elevated temperatures,electrical resistivity,and radiation resistance,have been widely utilized in high-temperature components,aerospace,electronics,and nuclear *** constituents of the topologically close-packed(TCP) phases,the sigma phase(σ) and chi phase(χ) formed within W-Re alloys wield considerable influence on the mechanical properties and the stability of the *** calculations were utilized in the present work to explore the structural,thermodynamic,and electronic properties of both ordered and disordered configurations within the σ and χ phases,culminating in a systematic elucidation of the higher phase stability exhibited by the ordered *** is found that the bulk modulus of these two phases is directly proportional to the concentration of Re in the alloy,while the equilibrium volume is inversely *** thermodynamic parameters of the σ and χ phases are calculated via the mean-field potential *** similar trends observed in the isobaric heat capacity,enthalpy increment,and entropy change curves for these two phases suggest they possess comparable thermodynamic *** is noteworthy that the contribution of ionic vibrations predominantly affects the isobaric heat capacity,while the contribution of thermal electronic excitations increases linearly with *** the structure and thermodynamic properties of TCP phases in W-Re alloys at low temperatures has profound significance for optimizing material performance,microstructures features,establishing theoretical foundations,and predicting material behavior.

关键词： First-principles calculations Phase stability TCP phases Thermodynamic properties W–Re alloy

High-dense nanocrystalline W-based alloy prepared by hot isostatic pressing with uniform microstructure, ultrahigh hardness and good thermal stability

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Tungsten 2025年第1期7卷 120-136页

作者： Zao-Ming Wu Lin He Lin-Sen Ye Xiao-Feng Yang Jia-Jia Zhang Hong-Bo Lei institute of Materials China Academy of Engineering Physics

High-density uniform microstructure nanocrystalline W-10wt.% Cr-5wt.% Y（W-10Cr-5Y） alloy with an average grain size of 85 nm and a relative density of 99.8% was successfully prepared.W-Cr-Y alloys with different amounts of second-phase particles were prepared by high-energy ball milling and hot isostatic pressing *** effects of composition design,ball milling parameters,and sintering parameters on the microstructure of W-Cr-Y alloys were studied.A feasible technology for controlling the synthesis of high-density nanocrystalline W-based alloys has been *** microstructure analysis of nanocrystalline W-10Cr-5Y alloy shows that there are two types of doping in the second phase:intergranular doping and intragranular *** "uniform distribution YOx-rich particles" effectively suppresses the grain growth of W and leads to the formation of nanocrystalline W-10Cr-5Y alloy.W-10Cr-5Y has an ultra-high hardness,with a Vickers hardness of 1312±12 kgf·***-temperature annealing treatment shows that W-10Cr-5Y has good thermal stability at 1000 and1100℃,as demonstrated by the comparison of Vickers hardness and grain size between annealed and unannealed alloys.

关键词： Hot isostatic pressing Microstructure Nanocrystalline tungsten Thermal stability Vickers hardness

Effects of bidirectional interaction on inelastic seismic response:When is its effect significant?

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake engineering and engineering Vibration 2025年第1期24卷 113-134页

作者： Atanu Santra Rana Roy Department of Aerospace engineering and Applied Mechanics Indian Institute of Engineering Science and TechnologyShibpur 711103India

Motivated by the early works on bidirectional interaction and the breakthrough to estimate seismic response to bidirectional shaking via unidirectional analysis,it is essential to answer the question:When is the interaction effect significant?Early works concluded that the effect of interaction is pronounced for stiff systems;consequently,the straightforward method for estimating seismic response to bidirectional excitation by using unidirectional analyses is verified primarily for short period ***,it is essential to identify the domain of significance for bidirectional interaction before adopting this simple methodology in *** parametrically defined systems with elastoplastic and degrading hysteresis models are studied under near-fault motions,assuming strength-independent and strength-dependent *** force-based and displacement-based analyses,conducted in parallel,reveal that the interaction effect is considerable for stiff systems,especially with degrading characteristics in a relatively low inelasticity ***,the bidirectional effect may be significant even for highly flexible systems,especially for residual deformation,which in earlier works was *** range of significance depends on the hysteresis model,system parameters,and response *** analysis is carried out with the results of the case studies,and the derived regression models may be used for a preliminary assessment of the impact of interaction in advance.

关键词： bidirectional residual forward-directive fling force-based displacement-based regression

维普期刊数据库

A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

在线全文

学校读者我要写书评

暂无评论

Applied mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： S.SAURABH R.KIRAN D.SINGH R.VAISH V.S.CHAUHAN School of Mechanical and Materials engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHSDT) of plates is employed to characterize the displacement field, with the incorporation of Green-Lagrange nonlinearity. The problem is modeled using the C0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(HR), helicoidal exponential(HE), helicoidal semi-circular(HS), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

关键词： bio-inspired composite plate finite element method (FEM) Green-Lagrange helicoidal inverse hyperbolic shear deformation theory (IHSDT) nonlinear O322

Statistical Research on Megahertz-peaked Spectra Pulsars

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2025年第1期25卷 116-134页

作者： Hong-Bing Cai Li Chen Shi-Dang Li Kai Wang Hang Liu JSNU SPBPU institute of engineering & SINO RUSSIAN institute Jiangsu Normal University School of Physics and Electronic engineering Jiangsu Normal University

Megahertz-peaked spectra(MPS) pulsars are referred as cases whose radio spectra turn over around 100 MHz. We identified 53 MPS pulsars based on the spectral data from the literature, and statistically analyzed the spatial location distribution, the magnetic field-period distribution, peak frequencies, spectral indices, and dispersion measures of these MPS pulsars. We found that there is a strong positive correlation between the dispersion measures and the peak frequencies of MPS pulsars, and negative correlations of the dispersion measures with spectral indices and the ages are also found. Such correlations suggest that the interstellar medium is an important factor that affects observational properties of MPS pulsars.

关键词： (stars:) pulsars: general ISM: general radio continuum: general

Unveiling solid-solid contact states in all-solid-state lithium batteries:An electrochemical impedance spectroscopy viewpoint

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第2期101卷 16-22页

作者： Jin-Liang Li Liang Shen Zi-Ning Cheng Jun-Dong Zhang Ling-Xuan Li Yu-Tong Zhang Yan-Bin Gao Chunli Guo Xiang Chen Chen-Zi Zhao Rui Zhang Qiang Zhang Tsinghua Center for Green Chemical engineering Electrification Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical Engineering Tsinghua University College of Materials Science and engineering Taiyuan University of Technology Advanced Research institute of Multidisciplinary Science School of Materials Science and Engineering Beijing Institute of Technology Beijing Huairou Laboratory institute for Carbon Neutrality Tsinghua University Shanxi Research institute for Clean Energy Tsinghua University

All-solid-state lithium batteries（ASSLBs） are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic *** solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental *** work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in *** the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery *** accurate fitting,inverse proportional relations between contact resistance Rcand（1-porosity） as well as crack angle was *** contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.

关键词： All-solid-state lithium batteries Distribution of relaxation times Electrochemical impedance spectroscopy Equivalent circuit model Finite element method Solid-solid contacts

Fabrication and fracture behaviors of the continuous brittle fiber reinforced tungsten composites fabricated via field-assisted sintering technology

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Tungsten 2025年第1期7卷 172-182页

作者： Rui Shu Yi-Ran Mao Jan W. Coenen Alexis Terra Stephan Sch?nen Johann Riesch Christian Linsmeier Christoph Broeckmann Juelich Research Center Institute of Energy and Climate Research Plasma Physics (IEK-4) Partner in the Trilateral Euregio Cluster institute of Materials Applications in Mechanical engineering (IWM) RWTH Aachen University Department of Nuclear engineering & engineering Physics University of Wisconsin Madison Central institute of engineering Electronics and Analytics Engineering and Technology (ZEA-1) Juelich Research Center Max Planck institute for Plasma Physics institute of Materials Applications in Mechanical engineering IWM RWTH Aachen University

Tungsten（W） is a promising candidate material for the plasma-facing components in future fusion ***,it has issues regarding the intrinsic brittleness as well as operational *** fiber reinforced tungsten（W_f/W） composites overcome these issues by using extrinsic toughening *** to neutron irradiation and high-temperature recrystallization during fusion operation,the ductility of the fibers may degrade over a long period of ***,it is necessary to investigate the fracture behavior of W_f/W composites with brittle *** the present work,the tungsten fibers were embrittled by ***,the continuous brittle W_f/W composite with yttrium oxide（Y2O3） interface was fabricated by the field-assisted sintering technology *** microstructure of the prepared W_f/W composites was *** fracture behavior and toughening mechanisms were discussed in detail based on the experimental results of 3-point bending tests and the corresponding finite element *** composites show a pseudo-ductile fracture *** are hindered and deflected by the de-bonded fiber-matrix *** extrinsic toughening mechanisms of interface de-bonding,crack bridging,and fiber pull-out are *** indicates the reinforcement concept still works even though all components in the W_f/W are brittle.

关键词： Field-assisted sintering technology (FAST) Fracture behavior Interface Numerical simulation Wf/W composites