In completeness theories of multiple-valued logic, the characterization of Sheffer functions is an important issue. The solution can be reduced to determining the minimal coverings of precomplete classes. In this pape...In completeness theories of multiple-valued logic, the characterization of Sheffer functions is an important issue. The solution can be reduced to determining the minimal coverings of precomplete classes. In this paper, someFull Symmetric Function Sets (m=3) are proved to be components of the minimal covering of precomplete classes inP k * . Keywords multiple-valued logic - completeness - Sheffer function - precomplete class NoteThis work is supported by the National Natural Science Foundation of China (Grant Nos.60083001 and 60375021).展开更多
The fuzzy C-means clustering algorithm(FCM) to the fuzzy kernel C-means clustering algorithm(FKCM) to effectively perform cluster analysis on the diversiform structures are extended, such as non-hyperspherical data, d...The fuzzy C-means clustering algorithm(FCM) to the fuzzy kernel C-means clustering algorithm(FKCM) to effectively perform cluster analysis on the diversiform structures are extended, such as non-hyperspherical data, data with noise, data with mixture of heterogeneous cluster prototypes, asymmetric data, etc. Based on the Mercer kernel, FKCM clustering algorithm is derived from FCM algorithm united with kernel method. The results of experiments with the synthetic and real data show that the FKCM clustering algorithm is universality and can effectively unsupervised analyze datasets with variform structures in contrast to FCM algorithm. It is can be imagined that kernel-based clustering algorithm is one of important research direction of fuzzy clustering analysis.展开更多
A nominative multi-proxy signature in which the original signer authorizes a group of proxy signers is presented. Meanwhile, our proposed scheme is based on elliptic curve cryptosystem which is more efficient than the...A nominative multi-proxy signature in which the original signer authorizes a group of proxy signers is presented. Meanwhile, our proposed scheme is based on elliptic curve cryptosystem which is more efficient than the corresponding one based on traditional discrete logarithm.展开更多
The state feedback design for singularly perturbed systems described in Delta operator is considered. The composite state feedback controller for slow and fast subsystems is designed by using the direct method. The ob...The state feedback design for singularly perturbed systems described in Delta operator is considered. The composite state feedback controller for slow and fast subsystems is designed by using the direct method. The obtained results can bring previous conclusions of continuous and discrete time systems into the unified Delta framework. A simulation example is presented to demonstrate the validity and efficiency of the design.展开更多
Based on the Kim-like's proxy multi-signature scheme, an improved proxymulti-signature scheme is proposed. The new scheme overcomes the two problems in the Kim-like'sproxy multi-signature scheme: (1) Security ...Based on the Kim-like's proxy multi-signature scheme, an improved proxymulti-signature scheme is proposed. The new scheme overcomes the two problems in the Kim-like'sproxy multi-signature scheme: (1) Security issue ( every original signer can forge a valid proxymulti-signature for any message); (2) Efficiency issue ( both the size of the proxy multi-signatureand the efficiency of signature checking are dependent on the number of the original signers).展开更多
The problem of direct adaptive neural network control for a class of uncertain nonlinear systems with unknown constant control gain is studied in this paper. Based on the supervisory control strategy and the approxima...The problem of direct adaptive neural network control for a class of uncertain nonlinear systems with unknown constant control gain is studied in this paper. Based on the supervisory control strategy and the approximation capability of multilayer neural networks (MNNs), a novel design scheme of direct adaptive neural network controller is proposed. The adaptive law of the adjustable parameter vector and the matrix of weights in the neural networks and the gain of sliding mode control term to adaptively compensate for the residual and the approximation error of MNNs is determined by using a Lyapunov method. The approach does not require the optimal approximation error to be square-integrable or the supremum of the optimal approximation error to be known. By theoretical analysis, the closed-loop control system is proven to be globally stable in the sense that all signals involved are bounded, with tracking error converging to zero. Simulation results demonstrate the effectiveness of the approach.展开更多
Upper and lower bounds on peak-to-mean envelope power ratio (PMEPR) in OFDM systems are derived in this paper. The derivation results show that the upper bound on PMEPR only depends on the aperiodic autocorrdation fun...Upper and lower bounds on peak-to-mean envelope power ratio (PMEPR) in OFDM systems are derived in this paper. The derivation results show that the upper bound on PMEPR only depends on the aperiodic autocorrdation functions of the data sequences and is quite useful for rapid elimination of sequences that have PMEPR exceeding a given threshold. According to the lower bound on PMEPR,it has a great change as N (number of subcarriers) varies only for a very small N. For a 16-subcarrier BPSK-OFDM system, a selective mapping (SLM) way to reduce PMEPR is investigated with the upper bound on PMEPR and the distribution of PMEPR for all possible message sequences is given. The analytic results show that the maximal PMEPR is about 6.5 dB which is 5.5 dB less than that in worst situation.展开更多
The upconversion energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass is investigated by time-resolved spectra. The effect of donor ion Yb^3＋ is involved in the dynamic decay behavior of acceptor...The upconversion energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass is investigated by time-resolved spectra. The effect of donor ion Yb^3＋ is involved in the dynamic decay behavior of acceptor ion Tb^3＋, which provides direct proof for the energy transfer from Yb^3＋ to Tb^3＋. The pump power dependence curves show that the upconversion luminescence is a two-photon process. The measured decay curves of the 5D4 state （Tb^3＋） contain two parts： a slow decay process corresponding to its radiation, and a fast one with a decay parameter approximately twice the lifetime of the ^2F5/2 state （Yb^3＋ ）. The fast decay process is contradictory to the generally accepted cooperative sensitization upconversion rate equation model. Since the effect of the host environmental is excluded by comparative experiments, we believe that there should be another energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass in addition to the cooperative sensitization process.展开更多
A method for simulation of cutting virtual soft tissue objects made of tetrahedron elements is developed. A linear isotropic elastic model is used for the soft tissue material properties and a tensor-mass model chosen...A method for simulation of cutting virtual soft tissue objects made of tetrahedron elements is developed. A linear isotropic elastic model is used for the soft tissue material properties and a tensor-mass model chosen for the physical deformation. The Verlet leapfrog method is used to perform time integration in solving the dynamic equations. Cutting is simulated by simply removing the tetrahedron elements that are intersected with the virtual scalpel. By making use of the spatial coherence, collision detection between soft tissue objects and the virtual scalpel is sped up. To facilitate the simulation, the soft tissue object is represented by linked lists of vertices, edges and tetra elements with pointers to the related neighboring features. The established software framework can serve as a base for the future development. Results of virtual experiments are shown and discussed. Possible future directions are also given.展开更多
文摘In completeness theories of multiple-valued logic, the characterization of Sheffer functions is an important issue. The solution can be reduced to determining the minimal coverings of precomplete classes. In this paper, someFull Symmetric Function Sets (m=3) are proved to be components of the minimal covering of precomplete classes inP k * . Keywords multiple-valued logic - completeness - Sheffer function - precomplete class NoteThis work is supported by the National Natural Science Foundation of China (Grant Nos.60083001 and 60375021).
文摘The fuzzy C-means clustering algorithm(FCM) to the fuzzy kernel C-means clustering algorithm(FKCM) to effectively perform cluster analysis on the diversiform structures are extended, such as non-hyperspherical data, data with noise, data with mixture of heterogeneous cluster prototypes, asymmetric data, etc. Based on the Mercer kernel, FKCM clustering algorithm is derived from FCM algorithm united with kernel method. The results of experiments with the synthetic and real data show that the FKCM clustering algorithm is universality and can effectively unsupervised analyze datasets with variform structures in contrast to FCM algorithm. It is can be imagined that kernel-based clustering algorithm is one of important research direction of fuzzy clustering analysis.
文摘A nominative multi-proxy signature in which the original signer authorizes a group of proxy signers is presented. Meanwhile, our proposed scheme is based on elliptic curve cryptosystem which is more efficient than the corresponding one based on traditional discrete logarithm.
基金This work was supported by the National Natural Science Foundation of China (No. 60474078,60304001).
文摘The state feedback design for singularly perturbed systems described in Delta operator is considered. The composite state feedback controller for slow and fast subsystems is designed by using the direct method. The obtained results can bring previous conclusions of continuous and discrete time systems into the unified Delta framework. A simulation example is presented to demonstrate the validity and efficiency of the design.
基金This work is supported by the Natural Science Foundation of China (No.60372094No.90204017) and"973"project of China (No.G1999035804).
文摘Based on the Kim-like's proxy multi-signature scheme, an improved proxymulti-signature scheme is proposed. The new scheme overcomes the two problems in the Kim-like'sproxy multi-signature scheme: (1) Security issue ( every original signer can forge a valid proxymulti-signature for any message); (2) Efficiency issue ( both the size of the proxy multi-signatureand the efficiency of signature checking are dependent on the number of the original signers).
文摘The problem of direct adaptive neural network control for a class of uncertain nonlinear systems with unknown constant control gain is studied in this paper. Based on the supervisory control strategy and the approximation capability of multilayer neural networks (MNNs), a novel design scheme of direct adaptive neural network controller is proposed. The adaptive law of the adjustable parameter vector and the matrix of weights in the neural networks and the gain of sliding mode control term to adaptively compensate for the residual and the approximation error of MNNs is determined by using a Lyapunov method. The approach does not require the optimal approximation error to be square-integrable or the supremum of the optimal approximation error to be known. By theoretical analysis, the closed-loop control system is proven to be globally stable in the sense that all signals involved are bounded, with tracking error converging to zero. Simulation results demonstrate the effectiveness of the approach.
文摘Upper and lower bounds on peak-to-mean envelope power ratio (PMEPR) in OFDM systems are derived in this paper. The derivation results show that the upper bound on PMEPR only depends on the aperiodic autocorrdation functions of the data sequences and is quite useful for rapid elimination of sequences that have PMEPR exceeding a given threshold. According to the lower bound on PMEPR,it has a great change as N (number of subcarriers) varies only for a very small N. For a 16-subcarrier BPSK-OFDM system, a selective mapping (SLM) way to reduce PMEPR is investigated with the upper bound on PMEPR and the distribution of PMEPR for all possible message sequences is given. The analytic results show that the maximal PMEPR is about 6.5 dB which is 5.5 dB less than that in worst situation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91123036 and 51105267, the Basic Research Priorities Program of Shanxi Province for Youths under Grant No 2012021013-1, the Shanxi Scholarship Council of China under Grant No 2010-030, the Science and Technology Major Project of the Shanxi Science and Technology Department under Grant No 20121101004, and the Key Disciplines Construction in Colleges and Universities of Shanxi Province under Grant No [2012]45.
文摘The upconversion energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass is investigated by time-resolved spectra. The effect of donor ion Yb^3＋ is involved in the dynamic decay behavior of acceptor ion Tb^3＋, which provides direct proof for the energy transfer from Yb^3＋ to Tb^3＋. The pump power dependence curves show that the upconversion luminescence is a two-photon process. The measured decay curves of the 5D4 state （Tb^3＋） contain two parts： a slow decay process corresponding to its radiation, and a fast one with a decay parameter approximately twice the lifetime of the ^2F5/2 state （Yb^3＋ ）. The fast decay process is contradictory to the generally accepted cooperative sensitization upconversion rate equation model. Since the effect of the host environmental is excluded by comparative experiments, we believe that there should be another energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass in addition to the cooperative sensitization process.
文摘A method for simulation of cutting virtual soft tissue objects made of tetrahedron elements is developed. A linear isotropic elastic model is used for the soft tissue material properties and a tensor-mass model chosen for the physical deformation. The Verlet leapfrog method is used to perform time integration in solving the dynamic equations. Cutting is simulated by simply removing the tetrahedron elements that are intersected with the virtual scalpel. By making use of the spatial coherence, collision detection between soft tissue objects and the virtual scalpel is sped up. To facilitate the simulation, the soft tissue object is represented by linked lists of vertices, edges and tetra elements with pointers to the related neighboring features. The established software framework can serve as a base for the future development. Results of virtual experiments are shown and discussed. Possible future directions are also given.
