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One-step estimation for varying coefficient models

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science china Mathematics 2005年第2期48卷 198-213页

作者： TANG Qingguo & WANG Jinde Department of Mathematics, nanjing university, nanjing 210093, china institute of sciences, pla university of science and technology, nanjing 210007, china 1. Department of Mathematics Nanjing University 210093 Nanjing China 2. institute of sciences PLA University of Science and Technology 210007 Nanjing China

A one-step method is proposed to estimate the unknown functions in the varying coefficient models, in which the unknown functions admit different degrees of smoothness. In this method polynomials of different orders are used to approximate unknown functions with different degrees of smoothness. As only one minimization operation is employed, the required computation burden is much less than that required by the existing two-step estimation method. It is shown that the one-step estimators also achieve the optimal convergence rate. Moreover this property is obtained under conditions milder than that imposed in the two-step estimation method. More importantly, as only one minimization operation is employed, the full asymptotic properties, not only the asymptotic bias and variance, but also the asymptotic distributions of the estimators can be derived. The asymptotic distribution results will play a key role for making statistical inference.

关键词： varying coefficient model, one-step estimation, asymptotic distribution, optimal convergence rate.

Entropy-based procedures for intuitionistic fuzzy multiple attribute decision making

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Journal of Systems Engineering and Electronics 2009年第5期20卷 1001-1011页

作者： Xu Zeshui~(1,2) & Hu Hui~3 1.School of Economics and Management,Southeast Univ.,nanjing 210096,p.r.china 2.Inst.of sciences,pla Univ.of sciences and technology,nanjing 210007,p.r.china 3.Inst.of Communications Engineering,pla Univ.of sciences and technology, nanjing 210007,p.r.china School of Economics and Management Southeast Univ. Nanjing 210096 P. R. China Inst. of Sciences PLA Univ. of Sciences and Technology Nanjing 210007 P. R. China Inst. of Communications Engineering PLA Univ. of Sciences and Technology Nanjing 210007 P. R. China

The class of multiple attribute decision making （MADM） problems is studied, where the attribute values are intuitionistic fuzzy numbers, and the information about attribute weights is completely unknown. A score function is first used to calculate the score of each attribute value and a score matrix is constructed, and then it is transformed into a normalized score matrix. Based on the normalized score matrix, an entropy-based procedure is proposed to derive attribute weights. Furthermore, the additive weighted averaging operator is utilized to fuse all the normalized scores into the overall scores of alternatives, by which the ranking of all the given alternatives is obtained. This paper is concluded by extending the above results to interval-valued intuitionistic fuzzy set theory, and an illustrative example is also provided.

关键词： multiple attribute decision making intuitionistic fuzzy number score matrix entropy additive weighted averaging operator.

Effective capacity region of two-user opportunistic spectrum access

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science china(Information sciences) 2011年第9期54卷 1928-1937页

作者： XU YuHua,WANG JinLong & WU QiHui institute of Communications Engineering,pla university of science and technology,nanjing 210007,china 1. institute of Communications Engineering PLA University of Science and Technology Nanjing 210007 China

The effective capacity region of the two-user opportunistic spectrum access (OSA) system in rayleigh fading environment is derived in this *** OSA is a contemporary research topic,little attention has been given to the capacity analysis under quality-of-service (QoS) ***,we use the effective capacity,which is a powerful tool to analyze the QoS requirements in wireless communication systems,to study the sustainable packet arrival rate of the secondary users while meeting statistical QoS *** derive the effective capacity region of the two-user OSA system and propose a method to obtain the capacity region *** addition,by combining the finite state channel model and the activity of the primary user,an extended finite state channel model for the two-user OSA system is also proposed.

关键词： cognitive radio opportunistic spectrum access effective capacity

Optimal MAC based cooperative spectrum sensing in cognitive radio networks

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science china(Information sciences) 2012年第6期55卷 1388-1396页

作者： CHEN Zhong 1,ZHANG XianDa 1 & YANG LanJuan 2 1 State Key Laboratory of Intelligent technology and Systems,Tsinghua National Laboratory for Information science and technology,Department of Automation,Tsinghua university,Beijing 100084,china 2.institute of Command Automation,pla university of science and technology,nanjing 210007,china 1. State Key Laboratory of Intelligent technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Automation Tsinghua University Beijing 100084 China2. Institute of Command Automation PLA University of Science and Technology Nanjing 210007 China

This paper considers a cognitive radio (Cr) system in non-ideal fading wireless channels and pro-poses cooperative spectrum sensing schemes based on coherent multiple access channels (MAC),serving as an alternative way to improve the cooperative spectrum sensing performance and provide space diversity for spec-trum *** statistics are transmitted using a common channel from the secondary users (SUs) to a fusion center (FC) where the global decision is *** optimal scaling factors of the proposed schemes are obtained by maximizing the detection probability under a target false alarm probability and a transmit power *** the proposed optimal MAC scheme has high computational complexity,a sub-optimal solu-tion based on maximization of the deflection coefficient (DC) is also *** results show that the proposed algorithms can significantly improve the spectrum sensing performance and approach the detection baseline.

关键词： cognitive radio (Cr) spectrum sensing multiple access channel (MAC) deflection coefficient optimization

Stability of a linear oscillator with damping force of the fractional-order derivative

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science china(physics,Mechanics & Astronomy) 2010年第2期53卷 345-352页

作者： WANG ZaiHua1,2 & HU HaiYan1 1 institute of Vibration Engineering research,nanjing university of Aeronautics and Astronautics,nanjing 210016,china 2.institute of science,pla university of science and technology,nanjing 211101,china 1. institute of Vibration Engineering research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

It begins with the study of damping representation of a linear vibration system of single degree of freedom (SDOF),from the view point of fractional calculus. By using the idea of stability switch,it shows that the linear term involving the fractional-order derivative of an order between 0 and 2 always acts as a damping force,so that the unique equilibrium is asymp-totically stable. Further,based on the idea of stability switch again,the paper proposes a scheme for determining the stable gain region of a linear vibration system under a fractional-order control. It shows that unlike the classical velocity feedback which can adjust the damping force only,a fractional-order feedback can adjust not only the damping force,but also the elastic re-storing force,and in addition,a fractional-order pDα control can either enlarge the stable gain region or narrow the stable gain region. For the dynamic systems described by integer-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay in the open left half-plane,while for the systems with fractional-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay within a sector in the complex plane. Analysis shows that the proposed method,based on the idea of stability switch,works effectively in the stability analysis of dynamical systems with fractional-order derivatives.

关键词： vibration system fractional-order derivative asymptotical stability stability switch

Delayed Hopf bifurcation in time-delayed slow-fast systems

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science china(Technological sciences) 2010年第3期53卷 656-663页

作者： ZHENG YuanGuang1 & WANG ZaiHua1,2 1 institute of Vibration Engineering research,nanjing university of Aeronautics and Astronautics,nanjing 210016,china 2.institute of science,pla university of science and technology,nanjing 211101,china 1. institute of Vibration Engineering research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential *** the two delayed's have different *** delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious *** a time-delayed system,the evolution of the system depends not only on the present state but also on past *** this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's *** shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.

关键词： time delay delayed bifurcation Hopf bifurcation slow-fast systems exit-point entry-exit function

Intuitionistic fuzzy hierarchical clustering algorithms

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Journal of Systems Engineering and Electronics 2009年第1期20卷 90-97页

作者： Xu Zeshui1,2 1. Coll. of Economics and Management, Southeast Univ., nanjing 210096, p. r. china 2. Inst. of sciences, pla Univ. of science and technology, nanjing 210007, p. r. china Coll. of Economics and Management Southeast Univ. Nanjing 210096 P. R. China Inst. of sciences PLA Univ. of Science and Technology Nanjing 210007 P. R. China

Intuitionistic fuzzy set （IFS） is a set of 2-tuple arguments, each of which is characterized by a membership degree and a nonmembership degree. The generalized form of IFS is interval-valued intuitionistic fuzzy set （IVIFS）, whose components are intervals rather than exact numbers. IFSs and IVIFSs have been found to be very useful to describe vagueness and uncertainty. However, it seems that little attention has been focused on the clustering analysis of IFSs and IVIFSs. An intuitionistic fuzzy hierarchical algorithm is introduced for clustering IFSs, which is based on the traditional hierarchical clustering procedure, the intuitionistic fuzzy aggregation operator, and the basic distance measures between IFSs： the Hamming distance, normalized Hamming, weighted Hamming, the Euclidean distance, the normalized Euclidean distance, and the weighted Euclidean distance. Subsequently, the algorithm is extended for clustering IVIFSs. Finally the algorithm and its extended form are applied to the classifications of building materials and enterprises respectively.

关键词： intuitionistic fuzzy set interval-valued intuitionistic fuzzy set hierarchical clustering intuitionisticfuzzy aggregation operator distance measure.

reducing component estimation for varying coefficient models with longitudinal data

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science china Mathematics 2008年第2期51卷 250-272页

作者： TANG QingGuo~(1,2+) WANG JinDe~2 1 institute of sciences,people’s Liberation Army university of science and technology,nanjing 210007,china 2 Department of Mathematics,nanjing university,nanjing 210093,china 1. institute of sciences People’s Liberation Army University of Science and Technology Nanjing 210007 China 2. Department of Mathematics Nanjing University Nanjing 210093 China

Varying-coefficient models with longitudinal observations are very useful in epidemiology and some other practical *** this paper,a reducing component procedure is proposed for es- timating the unknown functions and their derivatives in very general models,in which the unknown coefficient functions admit different or the same degrees of smoothness and the covariates can be time- *** asymptotic properties of the estimators,such as consistency,rate of convergence and asymptotic distribution,are *** asymptotic results show that the asymptotic variance of the reducing component estimators is smaller than that of the existing estimators when the coefficient functions admit different degrees of *** sample properties of our procedures are studied through Monte Carlo simulations.

关键词： varying coefficient model longitudinal data nonparametric estimation reducing component estimators asymptotic normality 62G07

A novel multicluster V-MIMO pCr scheme in large-scale Ad Hoc networks

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science china(Information sciences) 2010年第10期53卷 2097-2105页

作者： ZHOU Yao, CAI YueMing & pAN ChengKang Department of Wireless Communication, institute of Communications Engineering, pla university of science and technology, nanjing 210007, china 1. Department of Wireless Communication Institute of Communications Engineering PLA University of Science and Technology Nanjing 210007 China

A multicluster packet collision resolution (pCr) scheme is a kind of recently proposed virtualMIMO techniques. In existing multicluster pCr schemes, a large-scale wireless Ad Hoc network is divided into clusters and the single cluster pCr scheme is applied independently to resolve collisions in each cluster. However, there are still some flaws in existing multicluster pCr schemes. In this paper, by presenting a concise theoretical analysis model and a new CNS algorithm, a novel multicluster pCr scheme is proposed. Analysis and simulation results show that the proposed scheme can obtain high performance gain with low complexity. The proposed scheme is more robust and applicable than existing schemes.

关键词： packet collision resolution virtual-MIMO cooperative communication cooperative nodes selection