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Fast two-dimensional weighted least squares techniques for the design of two-dimensional finite impulse response filters

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控制理论与应用（英文版） 2013年第2期11卷 180-185页

作者： Ruijie ZHAO Xiaoping lai School of Mechanical Electrical and Information Engineering Shandong University at Weihai Institute of Information and Control Hangzhou Dianzi University

This paper focuses on the design of two-dimensional （2D） quadrantally symmetric finite impulse response （FIR） filters, and presents three very efficient algorithms for the weighted least squares （WLS） design with a weight matrix that assigns four different weights to four different frequency bands. The first algorithm seeks for iterative solutions to the matrix equation describing the optimality condition of the design problem. The second algorithm aims at the limit solution of the solution sequence to the first algorithm, analytically obtained by using matrix diagonalization techniques. The third algorithm belongs to the category of iterative reweighting techniques. It uses the second algorithm as its iteration core, and aims at reducing the maximum magnitude error of the filter by iteratively adjusting the four entry values of the weight matrix. Design examples are provided to demonstrate the performance of the proposed algorithms.

关键词： 2D FIR filters Diagonalization Quadrantal symmetry WLS design

ON THE EMBEDDING OF TOP IN THE CATEGORY OF STRATIFIED L-TOPOLOGICAL SPACES

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Chinese Annals of Mathematics,Series B 2005年第2期26卷 219-228页

作者： lai Hongliang ZHANG Dexue Department of Mathematics Sichuan UniversityChengdu 610064China Department of Mathematics Sichuan UniversityChengdu 610064China

Let L be a meet continuous lattice. It is proved that the category Top of topological spaces can be embedded in the category of strati?ed L-topological spaces as a concretely both re?ective and core?ective full subcat... 详细信息

关键词： Continuous lattice L-topological space Re?ective subcategory Core-flective subcategory

User centric dynamic web information visualization

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Science China(Information Sciences) 2013年第5期56卷 36-49页

作者： SALEHEEN Shibli lai Wei Faculty of Information and Communication Technologies Swinburne University of TechnologyHawthorn 3122VictoriaAustralia

Visualization of information after retrieval from the World Wide Web is a very challenging task because of the huge amount of data in *** on rules,information is retrieved through mining techniques and then visualized in different *** web-graph is one way for users to visualize web data and its *** because of its huge size,the web-graph lacks simplicity for end *** clustering plays a very important role in reducing the complexity of the web graph by making it compact and simple,existing clustering techniques are insufficient to provide personalized visualization for ***,these clustering techniques end up showing the same clustered graph to every user,despite their varying *** work aims to make information visualization personalized based on user interests;to provide a good first impression of web information to end users;to make web navigation easier;and to create scope for further ***,we develop a system for clustering which first considers user interests and then visualizes the clustered web graph to make the information more useful to the end *** this paper,we present some experimental examples that show the improvements achieved by our approach over existing ones.

关键词： information retrieval user profile clustering personalization visualization

Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly

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Science China(Physics,Mechanics & Astronomy) 2012年第11期55卷 2167-2178页

作者： lai GuoJun SHEN GongXin FFFOM Laboratory School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China

This paper focuses on flow structures of the wing-wake interaction between the hind wing and the wake of the forewing in hovering flight of a dragonfly since there are arguments whether the wing-wake interaction is useful or not.A mechanical flapping model with two tandem wings is used to study the *** the device,two identical simplified model wings are mounted to the flapping model and they are both scaled up to keep the Reynolds number similar to those of dragonfly in hovering flight since our experiment is conducted in a water *** kinetic pattern of dragonfly(Aeschna juncea) is chosen because of its special interesting asymmetry.A multi-slice phase-locked stereo particle image velocimetry(PIV) system is used to record flow structures around the hind wing at the mid downstroke(t/T=0.25) and the mid upstroke(t/T=0.75).To make comparison of the flow field between with and without the influence of the wake,flow structures around a single flapping wing(hind wing without the existence of the forewing) at these two stroke phases are also recorded.A local vortex identification scheme called swirling strength is applied to determine the vortices around the wing and they are visualized with the iso-surface of swirling *** paper also presents contour lines of z at each spanwise position of the hind wing,the vortex core position of the leading edge vortex(LEV) of hind wing with respect to the upper surface of hind wing,the circulation of the hind wing LEV at each spanwise position and so *** results show that dimension and strength of the hind wing LEV are impaired at the mid stroke in comparison with the single wing LEV because of the downwash from the *** results also reveal that a wake vortex from the forewing traverses the upper surface of the hind wing at the mid downstroke and its distance to the upper surface is about 40% of the wing chord *** the instant,the distance of the hind wing LEV to the upper surface is abo

关键词： dragonfly hovering flight particle image velocimetry (PIV) flow interaction leading edge vortex

New constructions for (multiparty) one-round key exchange with strong security

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Science China(Information Sciences) 2018年第5期61卷 332-337页

作者： Zheng YANG Junyu lai School of Computer Science and Engineering Chongqing University of Technology Department of Computer Science University of Helsinki School of Aeronautics and Astronautics University of Electronic Science and Technology of China

Dear editor,One-round key exchange(ORKE)represents a special class of two-message key *** enables two parties to establish a shared session key within only one communication *** first merit of ORKE is its communication efficiency,particularly because two parties are able to simultaneously run the protocol ***,the messages of two session participants(in an ORKE protocol)are completely independent.

关键词： New constructions for multiparty Eph DDH PFS

What is the effective key length for a block cipher: an attack on every practical block cipher

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Science China(Information Sciences) 2014年第7期57卷 138-148页

作者： HUANG JiaLin lai XueJia Cryptography and Information Security Lab Department of Computer ScienceShanghai Jiaotong University

Recently,several important block ciphers are considered to be broken by the brute-force-like cryptanalysis,with a time complexity faster than the exhaustive key search by going over the entire key space but performing less than a full encryption for each possible *** by this observation,we describe a meetin-the-middle attack that can always be successfully mounted against any practical block ciphers with success probability *** data complexity of this attack is the smallest according to the unicity *** time complexity can be written as 2k(1-),where>0 for all practical block ***,the security bound that is commonly accepted is the length k of the given master *** our result we point out that actually this k-bit security is always overestimated and can never be reached because of the inevitable loss of the key *** amount of clever design can prevent it,but increments of the number of rounds can reduce this key loss as much as *** give more insight into the problem of the upper bound of effective key bits in block ciphers,and show a more accurate bound.A suggestion about the relationship between the key size and block size is *** is,when the number of rounds is fixed,it is better to take a key size equal to the block ***,effective key bits of many well-known block ciphers are calculated and analyzed,which also confirms their lower security margins than thought *** results in this article motivate us to reconsider the real complexity that a valid attack should compare to.

关键词： block cipher effective key bits meet-in-the-middle brute-force attack

Weighted weak type (1,1) estimate for the Christ-Journé type commutator

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Science China Mathematics 2018年第3期61卷 517-534页

作者： Yong Ding Xudong lai School of Mathematical Sciences Beijing Normal University Beijing 100875 China Institute for Advanced Study in Mathematics Harbin Institute of Technology Harbin 150001 China

Let K be the Calderón-Zygmund convolution kernel on R^d(d≥2).Christ and Journé defined the commutator associated with K and a∈L~∞(R^d)by T_af(x)=p.v.∫_(R^d)K(x-y)m_x,y^a·f(y)dy,which is an extension of the classical Calderón commutator. In this paper, we show that T_a is weighted weak type(1,1) bounded with A,1 weight for d≥2.

关键词： Christ-Journe type commutator weighted weak type(1 1) A1 weight

DNA-chip-based dynamic broadcast encryption scheme with constant-size ciphertexts and decryption keys

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Science China(Information Sciences) 2014年第9期57卷 126-135页

作者： FANG XiWen lai XueJia Department of Computer Science and Engineering Shanghai Jiao Tong University

In this paper we present DNA-DBE,a DNA-chip-based dynamic broadcast encryption *** our scheme,new users can join dynamically without modification of other users’decryption *** the ciphertext or the decryption key is of *** secrecy is achieved in DNA-DBE:if new users join the system dynamically,they will not be able to retrieve past *** security of our scheme relies on hard biological problems,which are immune to attacks of new computing technologies in the *** exists a special feature in DNA–based cryptosystems,*** set of encryption keys and the set of decryption keys have a many-to-many *** implementation of more complicated DNA cryptosystems taking advantage of this special feature has been previously left as an open *** DNA-DBE system is a solution to this open problem,which is also the first exploration of DNA based group-oriented encryption system.

关键词： DNA cryptography dynamic broadcast encryption group oriented cryptography DNA chip cryptology

Synthesis, Characterization and Control of Proportion of Polymorph C in ITQ-16 and ITQ-17 Films

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Chemical Research in Chinese Universities 2016年第6期32卷 895-901页

作者： CHEN Yanli FENG lai College of Physics Optoelectronics and Enevgy Soochow University Suzhou 215006 P. R. China School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 P. R. China

Continuous ITQ-16 and ITQ-17 films on silicon wafer were prepared in fluoride media using TEAOH asorganic structure-directing agent. The proportion ofpolymorph C in the as-synthesized ITQ-16 and ITQ-17 films wasdetermined via X-ray diffraction characterization. The proportion of polymorph C in the ITQ-16 and 1TQ-17 filmswas controlled via optimizing the compositions of the reaction mixtures and reaction conditions, such as varyingthe Si/Ge molar ratio and adding n-propyl alcohol as a solvent in the reaction mixture, The Ge atoms in the reactionmedia strongly increased the crystallization of polymorph C in ITQ-16 and ITQ-17 films. Moreover, the stabilizingand buffering effect of n-propyl alcohol on crystal growth further enhanced the proportion of polymorph C in theITQ-16 and ITQ-17 films. For potential catalytic applications, A1 was incorporated into the framework ofpolymorphC, and a pure phase of polymorph C in Al-ITQ-17 film was achieved from the synthesis gel in the n-propyl alcohol phase.

关键词： Zeolite beta ITQ-16 ITQ-17 Polymorph C