检索结果-南通市图书馆

Plastic deformation of nanocrystalline nickel

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第8期52卷 2216-2221页

作者： WU XiaoLei state key laboratory of Nonlinear Mechanics, institute of Mechanics, chinese academy of sciences, beijing 100190, china state key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline (NC) Ni subject to cold rolling at liquid nitrogen temperature. The activation of grain-boundary-mediated-plasticity is evidenced in NC-Ni, including twinning and formation of stacking fault via partial dislocation slips from the grain boundary. The formation and storage of 60? full dislocations are observed inside NC-grains. The grain/twin boundaries act as the barriers of dislocation slips, leading to dislocation pile-up, severe lattice distortion, and formation of sub-grain boundary. The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation. The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

关键词： nanocrystalline metal plastic deformation deformation twinning dislocation microstructure

Security model and modular design of fair authentication key exchange protocols

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第2期53卷 278-287页

作者： FENG DengGuo & CHEN WeiDong state key laboratory of Information Security, institute of software, chinese academy of sciences, beijing 100190, china 1. state key laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China

It is traditionally assumed that the legal two parties in authentication key exchange (AKE) communications are both credible. However, in more and more network applications nowadays, it is often required that such protocols be run under the circumstances where ones do not trust in each other. Therefore, in this paper we propose the idea of fair authentication key exchange (FAKE), which has not only the basic properties of AKE protocols, but also some new properties: the "session proof" embedded in the input of protocols by the customer; and if not revealed, the protocols have the deniability, otherwise the transcript of protocol is binding for the identifications. Such a method is capable of solving the contradiction between protecting privacy and the dissension on network service. Then the security model of FAKE protocols is formulated systematically and a flaw of the security model of current signature schemes proposed by Kudla is also corrected. Finally, a kind of FAKE protocol based on current signature schemes is designed and the mBJM-AK security, conditional deniability and fairness of FAKE protocols are proved in the random oracle model.

关键词： authentication key exchange protocols deniability fairness concurrent signature provable security

Improved multi-pass fast correlation attacks with applications

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第8期54卷 1635-1644页

作者： ZHANG Bin & FENG DengGuo state key laboratory of Information Security,institute of software,chinese academy of sciences,beijing 100190,china 1. state key laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China

In this paper we propose two new algorithms for multi-pass fast correlation attacks on stream *** first algorithm aims at fast symbol-wise decoding in the circumstances that the noise is not very high and we have little resource for *** second algorithm deals with the practical decoding problem in the high noise and limited keystream *** new algorithms are applicable to arbitrary form LFSR and compare favorably to the previously known algorithms in the scenarios under *** applications,we demonstrate new key recovery attacks on one-level Bluetooth E0 and LILI-128,*** 2 37 -bit keystream and 2 28-byte memory,our attack against one-level E0 needs 2 35.1 *** 2 24-bit keystream and 2 24.5 -byte memory,our attack on LILI-128 has time complexity 2 70.6 operations.

关键词： stream cipher fast correlation attacks linear feedback shift register (LFSR) Bluetooth E0 LILI-128

NONPARAMETRIC APPROACH TO IDENTIFYING NARX 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

Journal of Systems science & Complexity 2010年第1期23卷 3-21页

作者： Qijiang SONG·Han-Pu CHEN key laboratory of Systems and Control,institute of Systems science,academy of Mathematics and Systems science,chinese academy of sciences,beijing 100190,china key laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences

This paper considers identification of the nonlinear autoregression with exogenous inputs(NARX system).The growth rate of the nonlinear function is required be not faster than linear withslope less than *** value of f(·) at any fixed point is recursively estimated by the stochasticapproximation (SA) algorithm with the help of kernel *** consistency of the estimatesis established under reasonable conditions,which,in particular,imply stability of the *** simulation is consistent with the theoretical analysis.

关键词： α-mixing geometrically ergodic Markov chains NARX nonparametric recursive estimate stochastic approximation strongly consistent.

A new class of three-variable orthogonal polynomials and their recurrences relations

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2008年第6期51卷 1071-1092页

作者： SUN JiaChang state key laboratory of computer science,R&D Center for Parallel Computing,institute of software,chinese academy of sciences,beijing 100080,china state key laboratory of computer science R & D Center for Parallel Computing Institute of Software Chinese Academy of Sciences Beijing 100080 China

A new class of three-variable orthogonal polynomials, defined as eigenfunctions of a second order PDE operator, is studied. These polynomials are orthogonal over a curved tetrahedron region, which can be seen as a mapping from a traditional tetrahedron, and can be taken as an extension of the 2-D Steiner domain. The polynomials can be viewed as Jacobi polynomials on such a domain. Three-term relations are derived explicitly. The number of the individual terms, involved in the recurrences relations, are shown to be independent on the total degree of the polynomials. The numbers now are determined to be five and seven, with respect to two conjugate variables z, $ \bar z $ and a real variable r, respectively. Three examples are discussed in details, which can be regarded as the analogues of the Chebyshev polynomials of the first and the second kinds, and Legendre polynomials.

关键词： 3-D PDE eigen-problem three-variable Chebyshev polynomials Legendre polynomial Jacobi polynomials recurrence relations 65N25 42C05 33C45

Effects of fundamental structure parameters on dynamic responses of submerged floating tunnel under hydrodynamic loads

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第3期25卷 335-344页

作者： Xu Long Fei Ge Lei Wang Youshi Hong state key laboratory of Nonlinear Mechanics, institute of Mechanics, chinese academy of sciences, beijing 100190, china state key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

This paper investigates the effects of structure parameters on dynamic responses of submerged floating tunnel （SFT） under hydrodynamic loads. The structure parameters includes buoyancy-weight ratio （BWR）, stiffness coefficients of the cable systems, tunnel net buoyancy and tunnel length. First, the importance of structural damp in relation to the dynamic responses of SPT is demonstrated and the mechanism of structural damp effect is discussed. Thereafter, the fundamental structure parameters are investigated through the analysis of SFT dynamic responses under hydrodynamic loads. The results indicate that the BWR of SFT is a key structure parameter. When BWR is 1.2, there is a remarkable trend change in the vertical dynamic response of SFT under hydrodynamic loads. The results also indicate that the ratio of the tunnel net buoyancy to the cable stiffness coefficient is not a characteristic factor affecting the dynamic responses of SFT under hydrodynamic loads.

关键词： Submerged floating tunnel Structural dampBuoyancy-weight ratio Cable stiffness coefficient ,Tunnel net buoyancy - Hydrodynamic load

Simulation of aerodynamic performance affected by vortex generators on blunt trailing-edge airfoils

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第1期53卷 1-7页

作者： YANG Ke1,2,ZHANG Lei1,3 & XU JianZhong1,2 1 institute of Engineering Thermophysics,chinese academy of sciences,beijing 100190,china 2 key laboratory of Wind Energy Utilization,chinese academy of sciences,beijing 100190,china 3 Graduate School of chinese academy of sciences,beijing 100190,china 1. institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China2. Key Laboratory of Wind Energy Utilization Chinese Academy of Sciences Beijing 100190 China3. Graduate School of Chinese Academy of Sciences Beijing 100190 China

An investigation was carried out by numerical simulation on a wind turbine airfoil and a blunt trailing-edge airfoil with and without vortex generators (VGs), and the performance of the airfoils was analyzed. By the simulation of airfoil DU 91-W2-250 it was verified that the numerical method and model were credible. Based on this airfoil, a new one with a blunt trailing edge of 6% chord was blended by symmetrically adding thickness, and its characteristics curves were obtained through computing at key angles of attack. Additionally, the pressure distribution on blended airfoil was analyzed by comparing to the airfoil without blend. The interaction of streamwise vortices induced by VGs with trailing vortex or separation vortex was considered, followed by the uncovery of how VGs can suppress the boundary layer separation.

关键词： vortex generators airfoil blunt trailing-edge

A two-round honest-verifier zero-knowledge protocol

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第5期53卷 954-963页

作者： LIU HanWu 1,2 & LIN DongDai 1 1 The state key laboratory of Information Security, institute of software, chinese academy of sciences, beijing 100190, china 2 Graduate University of the chinese academy of sciences, beijing 100049, china 1. The state key laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Since the concept of zero-knowledge protocols was introduced, it has attracted a lot of attention and in turn showed significant effect on the development of cryptography, complexity theory and other areas. The round complexity of a zero-knowledge protocol is a very important efficiency consideration, and it is required to be as small as possible. Generally, it is desirable to have zero-knowledge protocols with constant numbers of rounds. Goldreich and Oren proved that only languages in BPP have one-round and two-round zero-knowledge protocols. Moreover, they also showed that only languages in BPP have one-round honest-verifier zero-knowledge protocols. The notion of honest-verifier zero-knowledge protocols is highly non-trivial and fascinating itself, and has many other uses. Thus, the problem as to whether there exist two-round honest-verifier zero-knowledge protocols becomes an important open problem. In this paper, we introduce a new simulation technique and present a two-round honest-verifier zero-knowledge protocol for any language in N P under a standard complexity assumption based on this technique.

关键词： proof system argument system zero-knowledge witness indistinguishability black-box one-way permutation commitment scheme zap

CMQV+:An authenticated key exchange protocol from CMQV

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2012年第7期55卷 1666-1674页

作者： LI Hui 1,2 & WU ChuanKun 1 1 state key laboratory of Information Security,institute of software,chinese academy of sciences,beijing 100190,china 2 Graduate University of chinese academy of sciences,beijing 100049,china 1. state key laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Ustaoglu presents a secure and efficient key exchange protocol named CMQV,based on the design rationales of HMQV and *** with the latter two protocols,on one hand,CMQV achieves high performance of HMQV,and on the other,it is proven secure in eCK model as NAXOS ***,CMQV enjoys the security proof under gap Diffie-Hellman assumption as indicated by its *** this paper,we propose a variant of CMQV,called CMQV+,which is proven secure under a weaker assumption (*** Diffie-Hellman assumption) in eCK model with random oracles while maintaining the high-performance feature of CMQV as much as possible.

关键词： key exchange eCK model trapdoor-test technique provable security CDH assumption