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A note on characterization of Hardy space H^1

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Science china Mathematics 2005年第4期48卷 448-455页

作者： wang Silei department of Mathematics, zhejiang university, hangzhou 310028, china 1. department of Mathematics Zhejiang University 310028 Hangzhou China

An all-round answer is given to the following question: 'Find a necessary and sufficient size condition for an integrable compactly supported function on rn with mean value zero to be in the Hardy space H1.' Stefanov ... 详细信息

关键词： Hardy space riesz transform Hilbert transform

MECHANISM OF DEUTErIUM CrACKING IN pALLADIUM

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Acta Metallurgica Sinica(English Letters) 1993年第2期6卷 136-139页

作者： SUN Dalin LEI Yongquan CHEN Yanglin WU Jing wang Qidong zhejiang university,hangzhou,china department of Materials Science and Engineering,zhejiang university,hangzhou 310027,china zhejiang Univ Hangzhou China

After 290 h electrochemical charging of deuterium,the density of dislocation in well-annealed pd was increased from 10~8/cm^2 to over 10~12/cm^2 and a large amount of bubble-like voids or cracks was observed by optical and transmission electron *** mechanism of deuterium cracking is believed due to the formation of molecular De during the segregstion and combination of deuterium atoms around *** results showed that the lattice constant of pd increased from 0.3890 nm to 0.4034 nm.

关键词： deuterium cracking pd

SOME EXpErIMENTAL STUDIES OF BOUNDArY LAYEr CHArACTErISTICS ON THE OVErFLOW DAM BY LDA

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Journal of Hydrodynamics 1990年第1期2卷 29-36页

作者： wang Zhi-xin Chen Xi-zhen Mao Zhong-fu department of mechanics,zhejiang university,hangzhou 310027,p.r.china

The velocity profiles at six different cross sections and the development of the boundary layer over the surface of the overflow dam are *** on the experimental data using laser fcchnique the boundary layer thickness expression is *** velocity distributions within the boundary layer nearby the bottom of the dam are ana- *** fluctuating pressure on the overflow dam is compared with the fluctuating velocity nearby the bottom of the dam.

关键词： SOME EXpErIMENTAL STUDIES OF BOUNDArY LAYEr CHArACTErISTICS ON THE OVErFLOW DAM BY LDA

Stochastic optimal control of partially observable nonlinear quasi-integrable Hamiltonian systems

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Science china(physics,mechanics & Astronomy) 2010年第1期53卷 147-154页

作者： FENG Ju, ZHU WeiQiu & YING ZuGuang department of mechanics, State Key Laboratory of Fluid power Transmission and Control, zhejiang university, hangzhou 310027, china 1. department of mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

The stochastic optimal control of partially observable nonlinear quasi-integrable Hamiltonian systems is investigated. First, the stochastic optimal control problem of a partially observable nonlinear quasi-integrable Hamiltonian system is converted into that of a completely observable linear system based on a theorem due to Charalambous and Elliot. Then, the converted stochastic optimal control problem is solved by applying the stochastic averaging method and the stochastic dynamical programming principle. The response of the controlled quasi Hamiltonian system is predicted by solving the averaged Fokker-planck-Kolmogorov equation and the riccati equation for the estimated error of system states. As an example to illustrate the procedure and effectiveness of the proposed method, the stochastic optimal control problem of a partially observable two-degree-of-freedom quasi-integrable Hamiltonian system is worked out in detail.

关键词： quasi-integrable Hamiltonian system partial observation stochastic optimal control

Noise-Tolerant ZNN-Based Data-Driven Iterative Learning Control for Discrete Nonaffine Nonlinear MIMO repetitive Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 344-361页

作者： Yunfeng Hu Chong Zhang Bo wang Jing Zhao xun Gong Jinwu Gao Hong Chen State Key Laboratory of Automotive Simulation and Control Jilin UniversityJilin UniversityChangchun 130025China College of Communication Engineering Jilin UniversityJilin UniversityChangchun 130025China department of Electromechanical Engineering University of MacaoMacao 999078China School of Artificial Intelligence Jilin UniversityChangchun 130012China IEEE College of Electronics and Information Engineering Tongji UniversityShanghai 200092China

Aiming at the tracking problem of a class of discrete nonaffine nonlinear multi-input multi-output(MIMO) repetitive systems subjected to separable and nonseparable disturbances, a novel data-driven iterative learning control(ILC) scheme based on the zeroing neural networks(ZNNs) is proposed. First, the equivalent dynamic linearization data model is obtained by means of dynamic linearization technology, which exists theoretically in the iteration domain. Then, the iterative extended state observer(IESO) is developed to estimate the disturbance and the coupling between systems, and the decoupled dynamic linearization model is obtained for the purpose of controller synthesis. To solve the zero-seeking tracking problem with inherent tolerance of noise,an ILC based on noise-tolerant modified ZNN is proposed. The strict assumptions imposed on the initialization conditions of each iteration in the existing ILC methods can be absolutely removed with our method. In addition, theoretical analysis indicates that the modified ZNN can converge to the exact solution of the zero-seeking tracking problem. Finally, a generalized example and an application-oriented example are presented to verify the effectiveness and superiority of the proposed process.

关键词： Adaptive control control system synthesis data-driven iterative learning control neurocontroller nonlinear discrete time systems

An extension of Bernstein-Bezier surface over the triangular domain

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progress in Natural Science:Materials International 2007年第3期17卷 352-357页

作者： CAO Juan and wang Guozhao (Institute of Image processing and Computer Graphic, department of Mathematics, zhejiang university, hangzhou 310027, china) Institute of Image processing and Computer Graphic Department of Mathematics Zhejiang University Hangzhou 310027 China

In this paper, a set of quasi-Bernstein polynomials of degree n with one parameter is presented, which is an extension of the Bernstein polynomials over the triangular domain. Using the presented polynomials as basis functions, we construct a class of shape adjusting surfaces defined over the triangular domain with a shape parameter, namely, quasi-B-B parametric surfaces. These surfaces share many properties with the B-B parametric surfaces. In particular, when shape parameters equal 1, they degenerate to be the B-B parametric surfaces. By changing the value of the shape parameter, we can get different surfaces under the fixed control net.

关键词： triangular domain shape parameter Bezier surfaces.

STABILITY IN THE CIrCULAr pIpE FLOW OF FIBEr SUSpENSIONS

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Journal of Hydrodynamics 2003年第2期15卷 12-18页

作者： You Zhen jiang, Lin Jian zhong department of mechanics, State Key Laboratory of Fluid power Transmission and Control, zhejiang university, hangzhou 310027, china departmentofmechanics StateKeyLaboratoryofFluidPowerTransmissionandControlZhejiangUniversityHangzhou310027China

A linear stability analysis on the circular pipe flow of fiber suspensions ispresented. The fiber orientation tensors are used to describe the characteristics of theorientation dislribution of fibers. The constitutive equation for the fiber suspensions is set upand the modified Orr-Sommerfeld stability equation is derived. An improved finite difference methodwith high order accuracy is employed to solve the e-quation. The Newtonian pipe poiseuille flowcorresponding to H = 0 is also analyzed for comparison. The results reveal that the fiber additiveswill enhance the flow stability, the degree of enhancement becomes high with the increases of theparameter H which accounts for the fiber resistance to the stretching along its axis. Fibersuspensions with large H can suppress the influence of high reynolds number on the flow ***, fibers give a higher attenuation of the short waves of disturbance.

关键词： flow stability circular pipe flow fiber suspensions numerical simulation

Online uniform machine covering with the known largest size

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progress in Natural Science:Materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2 and Tan Zhiyi1,3(1. department of Mathematics, zhejiang university, hangzhou 310027, china 2. department of Mathematics, zhejiang Forestry university, hangzhou 311300, china 3. State Key Laboratory of CAD & CG, zhejiang university, hangzhou 310027, china) department of Mathematics Zhejiang University Hangzhou 310027 China department of Mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2 matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

Hydriding-dehydriding properties of Mg_2Ni alloy modified by ball-milling in tetrahydrofuran

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rare Metals 2004年第2期23卷 138-142页

作者： CHEN Changpin wang Wei CHEN Yun CHEN Lixin wang Qidong department of Materials Science and Engineering, zhejiang university hangzhou 310027, china department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China

A new approach of ball-milled Mg_2Ni in tetrahydrofuran (THF) to improve thehydriding kinetics of Mg_2Ni alloy is suggested and studied. It is found that the modified alloydisplayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K).In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 %at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to thechange of the structure, which is reflected by the broadening and weakening of the diffraction peaksin the XrD spectra. The XpS analysis shows that Mg (2s) binding energy peak of Mg_2Ni aftermodification shifted from a lower binding energy to a higher one, indicating the charge transferencebetween Mg and THF and the formation of catalytically active electron donor-acceptor (EDA)complexes on the surface of modified Mg_2Ni alloy.

关键词： metal materials Mg_2Ni alloy ball-milling tetrahydrofuran hydriding-dehydriding property