检索结果-南通市图书馆

Topological Multiple Recurrence of Weakly Mixing Minimal Systems for Generalized Polynomials

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2021年第12期37卷 1847-1874页

作者： Rui Feng ZHANG Jian jie zhao School of Mathematics Hefei University of TechnologyHefei 230009P.R.China CAS Wu Wen-Tsun Key Laboratory of Mathematics and School of Mathematics University of Science and Technology of ChinaHefei 230026P.R.China

Let(X,T)be a weakly mixing minimal system,p_(1),...,p_(d) be integer-valued generalized polynomials and(p_(1),p_(2),...,p_(d))be *** there exists a residual subset X_(0) of X such that for all x∈X0,{(T^(p1(n))x,...,T... 详细信息

关键词： Generalized polynomials weakly mixing multiple recurrence

Numerical study of air layer drag reduction of an axisymmetric body in oscillatory motions

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2021年第5期33卷 1007-1018页

作者： Xiao-jie zhao Zhi Zong Yi-chen Jiang School of Shipbuilding Engineering Dalian University of TechnologyDalian 116024China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian 116024China

The air layer drag reduction(ALDR)of an axisymmetric body in oscillatory motions is investigated in this paper with open source toolbox *** unsteady Reynolds-averaged Navier-Stokes(URANS)equations are used to determine the viscous flow and the volume of fluid(VOF)model is adopted to capture the interface of the air-water two-phase *** k-e turbulence model is adopted to simulate the *** dynamic mesh technique is applied to model the movement of the axisymmetric ***,the ALDR results are validated by the experimental ***,the effects of the movements of the body on the drag reduction during the ALDR state are *** representative kinds of movements are considered,namely,the pitch and the *** numerical results show that the drag reduction varies during the movements and the average drag reduction rates will be *** variation of the drag reduction is related to the morphological change of the air *** heave motion is more likely to reduce the effects of the ALDR than the pitch *** both oscillatory motions,the large motion amplitude and the low motion period are not conductive to improving the effects of the *** effects of the oscillatory motion on the ALDR are more sensitive at high water speeds than at low water ***,increasing the air flow ratio can be considered as one way to improve the effects of the ALDR.

关键词： Air layer drag reduction volume of fluid(VOF)model axisymmetric body pitch heave numerical simulation

QoS-Aware Computation Offloading in LEO Satellite Edge Computing for IoT:A Game-Theoretical Approach

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

Chinese Journal of Electronics 2024年第4期33卷 875-885页

作者： Ying CHEN Jintao HU jie zhao Geyong MIN School of Computer Science Beijing Information Science and Technology University University of Exeter

Low earth orbit(LEO) satellite edge computing can overcome communication difficulties in harsh environments, which lack the support of terrestrial communication infrastructure. It is an indispensable option for achieving worldwide wireless communication coverage in the future. To improve the quality-of-service(QoS) for Internet-of-things(IoT) devices, we combine LEO satellite edge computing and ground communication systems to provide network services for IoT devices in harsh environments. We study the QoS-aware computation offloading(QCO) problem for IoT devices in LEO satellite edge computing. Then we investigate the computation offloading strategy for IoT devices that can minimize the total QoS cost of all devices while satisfying multiple constraints, such as the computing resource constraint, delay constraint, and energy consumption constraint. We formulate the QoSaware computation offloading problem as a game model named QCO game based on the non-cooperative competition game among IoT devices. We analyze the finite improvement property of the QCO game and prove that there is a Nash equilibrium for the QCO game. We propose a distributed QoS-aware computation offloading(DQCO) algorithm for the QCO game. Experimental results show that the DQCO algorithm can effectively reduce the total QoS cost of IoT devices.

关键词： Satellites Costs Computational modeling Low earth orbit satellites Quality of service Games Nash equilibrium

Heterogeneous Cu catalyst in organic transformations

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第4期15卷 2810-2833页

作者： Ruixue Zhang Yan Chen Muhua Ding jie zhao Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing 100084China

Copper catalysis plays a crucial role in organic synthesis providing a wide spectrum of important transformations over *** in homogeneous copper catalysis has often relied on the appropriate modulation of coordinating ligands,whereas the development of the corresponding heterogeneous variant has relatively gained less *** this review,we aim to deliver a comprehensive summary of a number of seminal heterogenized Cu-catalyzed homogenous catalysis reported over the last *** scope of this review is classified by the type of transformations in which the catalyst’s preparation and activity including the relationship between structure and activity are *** this way,this review highlights the potential and synthetic perspectives of heterogeneous copper catalysis in both academic and industry.

关键词： copper heterogeneous catalysis organic reactions

Quaternion-Based Adaptive Trajectory Tracking Control of a Rotor-Missile with Unknown Parameters Identification

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

Defence Technology（防务技术） 2024年第1期31卷 375-386页

作者： jie zhao Zhongjiao Shi Yuchen Wang Wei Wang Beijing Institute of Technology Beijing 100081China

This paper investigates the adaptive trajectory tracking control problem and the unknown parameter identification problem of a class of rotor-missiles with parametric system ***,considering the uncertainty of structural and aerodynamic parameters,the six-degree-of-freedom(6Do F) nonlinear equations describing the position and attitude dynamics of the rotor-missile are established,respectively,in the inertial and body-fixed reference ***,a hierarchical adaptive trajectory tracking controller that can guarantee closed-loop stability is proposed according to the cascade characteristics of the 6Do F ***,a memory-augmented update rule of unknown parameters is proposed by integrating all historical data of the regression *** long as the finitely excited condition is satisfied,the precise identification of unknown parameters can be ***,the validity of the proposed trajectory tracking controller and the parameter identification method is proved through Lyapunov stability theory and numerical simulations.

关键词： Rotor-missile Adaptive control Parameter identification Quaternion control

Web Resources for Mass Spectrometry-based Proteomics

在线全文

学校读者我要写书评

暂无评论

Genomics, Proteomics & Bioinformatics 2015年第1期13卷 36-39页

作者： Tao Chen jie zhao jie Ma Yunping Zhu State Key Laboratory of Proteomics Beijing Proteome Research Center Beijing Institute of Radiation Medicine Biological Information College Chongqing University of Posts and Telecommunications

With the development of high-resolution and high-throughput mass spectrometry（MS）technology, a large quantum of proteomic data is continually being generated. Collecting and sharing these data are a challenge that requires immense and sustained human effort. In this report, we provide a classification of important web resources for MS-based proteomics and present rating of these web resources, based on whether raw data are stored, whether data submission is supported,and whether data analysis pipelines are provided. These web resources are important for biologists involved in proteomics research.

关键词： Mass spectrometry Proteomics Web resources

Supercritical fluid extraction and gas chromatography analysis of arsenic species from solid matrices

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2016年第2期27卷 241-246页

作者： Zhi-Feng Wang zhao-jie Cui School of Environmental Science and Engineering Shandong University

A method in combination with derivatization-supercritical fluid extraction（SFE） and gas chromatography（GC） for the speciation and quantitative determination of dimethylarsinate（DMA）, monomethylarsonate（MMA） and inorganic arsenic in solid matrices was investigated. Thioglycolic acid methyl ester（TGM） and thioglycolic acid ethyl ester（TGE） were evaluated as derivatization reagents. The effects of pressure, temperature, flow rate of supercritical CO_2, extraction time, modifier and microemulsion on the efficiency of extraction were systematically investigated. The procedure was applied to the analysis of real soil and sediment samples. Results showed that TGE was more effective for arsenic speciation as a derivatization reagent. Modifying supercritical CO_2 with methanol can greatly improve the extraction efficiency. Further, the addition of microemulsion containing surfactant Triton X-100 can further enhance recoveries of arsenic species. The optimum extraction conditions were 100 ℃, 30 MPa, 10 min static and 25 min dynamic extraction with 5%（v/v） methanol, and surfactant modified supercritical CO_2. Detection limits in solid matrices were 0.15, 0.3 and 1.2 mg/kg for DMA, MMA and inorganic arsenic,respectively. The method was validated by the recovery data. The resulting method was fast, easy to perform and selective in the extraction and detection of various arsenic species in solid matrices.

关键词： Supercritical fluid extraction Arsenic species analysis Thioglycolic acid methyl ester(TGM) Thioglycolic acid ethyl ester(TGE) Derivatization Gas chromatography

Fracture behavior of 304 stainless steel coatings by cold gas dynamic spray

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 249-254页

作者： Wei HAN Xianming MENG jie zhao Junbao ZHANG School of Materials Science and Engineering Dalian University of Technology Dalian 116085 China Baosteel Research Institute Baoshan Iron & Steel Co. Ltd. Shanghai 201900 China

304 stainless steel coating was deposited on the Interstitial-Free steel substrate by cold gas dynamic spraying （CGDS）. Three-point bending test of the cold sprayed 304 stainless steel coating was tested by SHIMADZU electro-hydraulic servo-controlled fatigue testing machine and the fracture morphology was examined by scanning electron microscopy. The results showed that the fracture behavior of the cold sprayed 304 stainless steel coating was brittleness fracture. The crack in the coating occurred in the interfaces between particles and the crack extended to the internal of the coating with the increase of the load. When the crack has extended to the combination interface between coating and substrate, the crack extended to the two sides. The microstructure and mechanical property of the cold sprayed 304 stainless steel coating have been optimized after heat treatment.

关键词： Cold gas dynamic spraying 304 stainless steel coating Three- point bending test Fracture behavior Heat treatment

Pressure-sensitive plasticity of lithiated silicon in Li-ion batteries

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第3期29卷 379-387页

作者： Ke-jie zhao Yong-Gang Li Laurence Brassart Department of Nuclear Science and Engineering and Materials Science and Engineering Massachusetts Institute of Technology Key Laboratory for Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Institute of Mechanics Materials and Civil Engineering Université catholique de Louvain

Lithiation-induced plasticity is a key factor that enables Si electrodes to maintain long cycle life in Li-ion batteries. We study the plasticity of various lithiated sili-con phases based on first-principles calculations and iden-tify the linear dependence of the equivalent yield stress on the hydrostatic pressure. Such dependence may cause the compression-tension asymmetry in an amorphous Si thin film electrode from a lithiation to delithiation cycle, and leads to subsequent ratcheting of the electrode after cyclic lithiation. We propose a yield criterion of amorphous lithi-ated silicon that includes the effects of the hydrostatic stress and the lithiation reaction. We further examine the micro-scopic mechanism of deformation in lithiated silicon under mechanical load, which is attributed to the flow-defects mediated local bond switching and cavitation. Hydrostatic compression confines the flow defects thus effectively strength-ens the amorphous structure, and vice versa.

关键词： Li-ion batteries · Si · Pressure-sensitive plasticity · Ratcheting.