检索结果-南通市图书馆

Memristive oscillator to memristive map,energy characteristic

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2024年第5期67卷 1567-1578页

作者： GUO YiTong MA Jun zhang XiaoFeng HU XiKui College of Electrical and Information engineering Lanzhou University of TechnologyLanzhou730050China Department of Physics Lanzhou University of TechnologyLanzhou730050China School of Science Chongqing University of Posts and TelecommunicationsChongqing400065China

Most of nonlinear oscillators composed of capacitive and inductive variables can obtain the Hamilton energy by using the Helmholtz theorem when the models are rewritten in equivalent vector *** energy functions for biophysical neurons can be obtained by applying scale transformation on the physical field energy in their equivalent neural *** dynamical systems often have exact energy functions,while some mathematical models just suggest generic Lyapunov functions,and the energy function is effective to predict mode *** this paper,a memristive oscillator is approached by two kinds of memristor-based nonlinear circuits,and the energy functions are defined to predict the dependence of oscillatory modes on energy *** absence of capacitive variable for capacitor,the physical time t and charge q are converted into dimensionless variables by using combination of resistance and inductance(L,R),e.g.,τ=t×R/*** energy function for each memristive map is proposed by applying the similar weights as energy function for the memristive *** example,energy function for the map is obtained by replacing the variables and parameters of the memristive oscillator with corresponding variables and parameters for the memristive *** memristive map prefers to keep lower average energy than the memristive oscillator,and chaos is generated in a discrete system with two *** scheme is helpful for energy definition in maps,and it provides possible guidance for verifying the reliability of maps by considering the energy characteristic.

关键词： Hamilton energy memristor Helmholtz theorem scale transformation memristive circuit

Mechanical behavior and damage constitutive model of sandstone under hydro-mechanical (H-M) coupling

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2024年第6期34卷 837-853页

作者： Tao Tan Chunyang zhang Yanlin Zhao Xiaoshuang Li School of Resources and Environmental engineering Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Safety and Health in Metal Mines Maanshan 243000China Sinosteel Maanshan General institute of Mining Research Co. Ltd.Maanshan 243000China School of Resource&Environment and Safety engineering Hunan University of Science and TechnologyXiangtan 411201China School of Urban Construction Changzhou UniversityChangzhouJiangsu 213164China

Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-C) model has become the focus of attention. Considering the inadequacy of the current research on rock strength parameters,energy evolution characteristics and D-C model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of characteristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-Coulomb(M-C) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution characteristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage efficiency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-C models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-C models have high {1., and can characterize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-C models

关键词： H-M coupling Water-saturated sandstone Mechanical mechanism Energy evolution D-C model

Hadoop-based secure storage solution for big data in cloud computing environment

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第1期10卷 227-236页

作者： Shaopeng Guan Conghui zhang Yilin Wang Wenqing Liu School of Information and Electronic engineering Shandong Technology and Business UniversityYantai264003China

In order to address the problems of the single encryption algorithm,such as low encryption efficiency and unreliable metadata for static data storage of big data platforms in the cloud computing environment,we propose a Hadoop based big data secure storage ***,in order to disperse the NameNode service from a single server to multiple servers,we combine HDFS federation and HDFS high-availability mechanisms,and use the Zookeeper distributed coordination mechanism to coordinate each node to achieve dual-channel ***,we improve the ECC encryption algorithm for the encryption of ordinary data,and adopt a homomorphic encryption algorithm to encrypt data that needs to be *** accelerate the encryption,we adopt the dualthread encryption ***,the HDFS control module is designed to combine the encryption algorithm with the storage *** results show that the proposed solution solves the problem of a single point of failure of metadata,performs well in terms of metadata reliability,and can realize the fault tolerance of the *** improved encryption algorithm integrates the dual-channel storage mode,and the encryption storage efficiency improves by 27.6% on average.

关键词： Big data security Data encryption Hadoop Parallel encrypted storage Zookeeper

Formal Verification of Data Modifications in Cloud Block Storage Based on Separation Logic

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第1期33卷 112-127页

作者： Bowen zhang Zhao JIN Hanpin WANG Yongzhi CAO Key Laboratory of High Confidence Software Technologies (MOE) School of Computer Science Peking University School of Computer and Artificial Intelligence Zhengzhou University School of Computer Science and Cyber engineering Guangzhou University

Cloud storage is now widely used, but its reliability has always been a major concern. Cloud block storage(CBS) is a famous type of cloud storage. It has the closest architecture to the underlying storage and can provide interfaces for other types. Data modifications in CBS have potential risks such as null reference or data *** verification of these operations can improve the reliability of CBS to some extent. Although separation logic is a mainstream approach to verifying program correctness, the complex architecture of CBS creates some challenges for verifications. This paper develops a proof system based on separation logic for verifying the CBS data modifications. The proof system can represent the CBS architecture, describe the properties of the CBS system state, and specify the behavior of CBS data modifications. Using the interactive verification approach from Coq, the proof system is implemented as a verification tool. With this tool, the paper builds machine-checked proofs for the functional correctness of CBS data modifications. This work can thus analyze the reliability of cloud storage from a formal perspective.

关键词： Cloud computing Behavioral sciences reliability Formal verification

Impact response and energy absorption of metallic buffer with entangled wire mesh damper

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第5期35卷 137-150页

作者： Chao Zheng Jun Wu Mangong zhang Xin Xue institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China wuhan Second Ship Design and Research {1. Wuhan 430205China

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of {1. *** impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(1.0-200 mm)are investigated using experimental and numerical *** results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness *** loss factor gradually increases with increasing compression deformation before entering the stiffness hardening *** impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(1.0 mm),resulting in the best impact isolation effect of metallic ***,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening ***,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness ***,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

关键词： Metallic buffer Hat-shaped EWMD Drop impact Energy absorption characteristics Mechanical behavior

Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

在线全文

学校读者我要写书评

暂无评论

Bio-Design and Manufacturing 2024年第1期7卷 1-13页

作者： Huaizhi Zong Junhui zhang Lei Jiang Kun zhang Jun Shen Zhenyu Lu Ke Wang Yanli Wang Bing Xu The State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310058China Unmanned Vehicle Research and Development Center China North Vehicle Research InstituteBeijing 100072China School of Mechatronic engineering Nanchang UniversityNanchang 330031China Auclean High-Tech Ltd. Wuxi 214108China

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped *** various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large *** the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight *** by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an *** propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston *** addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the *** mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah *** mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

关键词： Additive manufacturing Bionic lightweight design Limb leg unit Quadruped robot Trajectory tracking

Robust and Trustworthy Data Sharing Framework Leveraging On-Chain and Off-Chain Collaboration

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第2期78卷 2159-2179页

作者： Jinyang Yu Xiao zhang Jinjiang Wang Yuchen zhang Yulong Shi Linxuan Su Leijie Zeng School of Computer Science Northwestern Polytechnical UniversityXi’an710072China MIIT Key Laboratory of Big Data Storage and Management Northwestern Polytechnical UniversityXi’an710072China National engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Northwestern Polytechnical UniversityXi’an710072China

The proliferation of Internet of Things(IoT)systems has resulted in the generation of substantial data,presenting new challenges in reliable storage and trustworthy *** distributed storage systems are hindered by centralized management and lack traceability,while blockchain systems are limited by low capacity and high *** address these challenges,the present study investigates the reliable storage and trustworthy sharing of IoT data,and presents a novel system architecture that integrates on-chain and off-chain data manage *** architecture,integrating blockchain and distributed storage technologies,provides high-capacity,high-performance,traceable,and verifiable data storage and *** on-chain system,built on Hyperledger Fabric,manages metadata,verification data,and permission information of the raw *** off-chain system,implemented using IPFS Cluster,ensures the reliable storage and efficient access to massive files.A collaborative storage server is designed to integrate on-chain and off-chain operation interfaces,facilitating comprehensive data *** provide a unified access interface for user-friendly system *** testing validates the system’s reliability and stable *** proposed approach significantly enhances storage capacity compared to standalone blockchain *** reliability tests consistently yield positive *** average upload and download throughputs of roughly 20 and 3. MB/s,respectively,the system’s throughput surpasses the blockchain system by a factor of 4 to 1..

关键词： On-chain and off-chain collaboration blockchain distributed storage system hyperledger fabric IPFS cluster

Probabilistic-Ellipsoid Hybrid reliability Multi-Material Topology Optimization Method Based on Stress Constraint

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in engineering & Sciences 2024年第7期140卷 757-792页

作者： Zibin Mao Qinghai Zhao Liang zhang College of Mechanical and Electrical engineering Qingdao UniversityQingdao266071China National engineering Research Center for Intelligent Electrical Vehicle Power System Qingdao UniversityQingdao266071China

This paper proposes a multi-material topology optimization method based on the hybrid reliability of the probability-ellipsoid model with stress constraint for the stochastic uncertainty and epistemic uncertainty of mechanical loads in optimization *** probabilistic model is combined with the ellipsoidal model to describe the uncertainty of mechanical *** topology optimization formula is combined with the ordered solid isotropic material with penalization(ordered-SIMP)multi-material interpolation *** stresses of all elements are integrated into a global stress measurement that approximates the maximum stress using the normalized p-norm ***,the sequential optimization and reliability assessment(SORA)is applied to transform the original uncertainty optimization problem into an equivalent deterministic topology optimization(DTO)*** response surface and sparse grid technique are combined with SORA to get accurate information on the most probable failure point(MPP).In each cycle,the equivalent topology optimization formula is updated according to the MPP information obtained in the previous *** adjoint variable method is used for deriving the sensitivity of the stress constraint and the moving asymptote method(MMA)is used to update design ***,the validity and feasibility of the method are verified by the numerical example of L-shape beam design,T-shape structure design,steering knuckle,and 3. T-shaped beam.

关键词： Stress constraint probabilistic-ellipsoid hybrid topology optimization reliability analysis multi-material design

Highly strengthening and toughening biomimetic ceramic structures fabricated via a novel coaxially printing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第4期13卷 403-412页

作者： Kunkun Song Shengda Yang Ningqi Shao Yantang Zhao Peng He Yongfeng Wei Hengzhong Fan Yongsheng zhang Qiangqiang zhang State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China School of Civil engineering and Mechanics Lanzhou UniversityLanzhou 730000China Key Laboratory of Mechanics on Disaster and Environment in Western china(Lanzhou {1.) Ministry of EducationLanzhou 730000.China

Additive manufacturing technology,by manipulating and emulating inherent multiscale,multi-material,and multifunctional structures found in nature,has created new opportunities for constructing heterogeneous structures associated with special properties and achieving ultra-high mechanical performance and reliability in ceramic composite *** this study,we have developed an innovative fabrication method designated as coaxial 3. printing for the synchronous construction of two constituents into ceramic composites with a tooth enamel biomimetic ***,the stiff silicate and flexible epoxy served as a strengthening bridge and toughening layer,*** method differed from the traditional approach of randomly dispersing reinforcing components within a ceramic *** allowed for the direct creation of an internally effective three-dimensional reinforcement network structure in ceramic *** process facilitated synergistic deformation and simultaneous enhancement of multiple materials and hierarchical *** to the uniform distribution of internal stress and effective block of microcrack propagation,the biomimetically structured silicate/epoxy ceramic composite has demonstrated much significant enhancement in mechanical properties,includingcompressive strength(48.8±3.1.MPa),flexuralstrength(1..3.±1.23.Pa),andflexuraltoughness(21..7±54.6kJ/m^(3.),which was 0.5,2.1.and 47.5 times as high as those of the intrinsic brittle silicate ceramics,***-situ characterization and multiscale finite element simulation of microstructural evolution during three-point bending deformation further validated multiple-step features of the fracture process(silicate bridge fracture,interface detachment,epoxy extraction,and rupture),which benefited from interpenetrating structural features achieved by coaxial printing to accomplish with the complex propagating routines of the crack deflection in silicate ceramic *** coaxia

关键词： coaxial 3. printing silicate ceramic composites enamel biomimetic microstructure strengthening bridge tougheninglayer crackdeflection