共查询到20条相似文献,搜索用时 15 毫秒
1.
M. E. Shaikin 《Automation and Remote Control》2009,70(2):173-202
We consider stochastic control systems subjected simultaneously to stochastic and determinate perturbations. Stochastic perturbations are assumed to be state-multiplicative stochastic processes, while determinate perturbations can be any processes with finite energy on infinite time interval. The results of the determinate H ∞-theory are compared to their stochastic analogs. The determinate and stochastic theories are linked together by the lemma that establishes the equivalence between the stability and boundness of the ‖L‖∞ < γ norm of the perturbation operator L, from one side, and the solvability of certain linear matrix inequalities (LMIs), from the other side. As soon as the stochastic version of the lemma is proven, the γ-controller analysis and design problems are solved, in general, identically in the frame of the united LMI methodology. 相似文献
2.
Song Wan Yuliang Lu Xuehu Yan Yongjie Wang Chao Chang 《Journal of Real-Time Image Processing》2018,14(1):25-40
In this paper, a novel visual secret sharing (VSS) scheme based on QR code (VSSQR) with (k, n) threshold is investigated. Our VSSQR exploits the error correction mechanism in the QR code structure, to generate the bits corresponding to shares (shadow images) by VSS from a secret bit in the processing of encoding QR. Each output share is a valid QR code that can be scanned and decoded utilizing a QR code reader, which may reduce the likelihood of attracting the attention of potential attackers. Due to different application scenarios, two different recovered ways of the secret image are given. The proposed VSS scheme based on QR code can visually reveal secret image with the abilities of stacking and XOR decryptions as well as scan every shadow image, i.e., a QR code, by a QR code reader. The secret image could be revealed by human visual system without any computation based on stacking when no lightweight computation device. On the other hand, if the lightweight computation device is available, the secret image can be revealed with better visual quality based on XOR operation and could be lossless revealed when sufficient shares are collected. In addition, it can assist alignment for VSS recovery. The experiment results show the effectiveness of our scheme. 相似文献
3.
Sylvie Alayrangues Xavier Daragon Jacques-Olivier Lachaud Pascal Lienhardt 《Journal of Mathematical Imaging and Vision》2008,32(1):1-22
Many combinatorial structures have been designed to represent the topology of space subdivisions and images. We focus here
on two particular models, namely the n-G-maps used in geometric modeling and computational geometry and the n-surfaces used in discrete imagery. We show that a subclass of n-G-maps is equivalent to n-surfaces. To achieve this, we provide several characterizations of n-surfaces. Finally, the proofs being constructive, we show how to switch from one representation to another effectively.
相似文献
Pascal LienhardtEmail: |
4.
Timothy M. Chan 《Algorithmica》2008,50(2):236-243
We describe an O(n
3/log n)-time algorithm for the all-pairs-shortest-paths problem for a real-weighted directed graph with n vertices. This slightly improves a series of previous, slightly subcubic algorithms by Fredman (SIAM J. Comput. 5:49–60,
1976), Takaoka (Inform. Process. Lett. 43:195–199, 1992), Dobosiewicz (Int. J. Comput. Math. 32:49–60, 1990), Han (Inform. Process. Lett. 91:245–250, 2004), Takaoka (Proc. 10th Int. Conf. Comput. Comb., Lect. Notes Comput. Sci., vol. 3106, pp. 278–289, Springer, 2004), and Zwick (Proc. 15th Int. Sympos. Algorithms and Computation, Lect. Notes Comput. Sci., vol. 3341, pp. 921–932, Springer,
2004). The new algorithm is surprisingly simple and different from previous ones.
A preliminary version of this paper appeared in Proc. 9th Workshop Algorithms Data Struct. (WADS), Lect. Notes Comput. Sci.,
vol. 3608, pp. 318–324, Springer, 2005. 相似文献
5.
This paper presents a simultaneous H2/H∞ stabilization problem for the chemical reaction systems which can be modeled as a finite collection of subsystems. A single dynamic output feedback controller which simultaneously stabilizes the multiple subsystems and captures the mixed H2/H∞ control performance is designed. To ensure that the stability condition, the H2 characterization and the H∞ characterization can be enforced within a unified matrix inequality framework, a novel technique based on orthogonal complement space is developed. Within such a framework, the controller gain is parameterized by the introduction of a common free positive definite matrix, which is independent of the multiple Lyapunov matrices. An iterative linear matrix inequality (ILMI) algorithm using Matlab Yalmip toolbox is established to deal with the proposed framework. Simulation results of a typical chemical reaction system are exploited to show the validity of the proposed methodology. 相似文献
6.
We propose a novel (t,n)–threshold secret image sharing scheme based on Shamir’s polynomial interpolation paradigm. The proposed scheme is a derivative of Thien and Lin’s (Computers & Graphics 26(5):765–770, [13]) and some of its variants by ensuring less intrusive changes in the secret image. This is achieved by cyclically shifting the bits of the secret image, thus allowing a modification in the least significant bit to have a large effect on the values used in computation of shadow images. Statistical tests and simulations are presented to show the efficiency and robustness of the proposed scheme, in particular good randomness of shadow images, little correlation between adjacent pixels, and high entropy. Competence of the proposed scheme is further demonstrated by means of comparison with existing schemes. 相似文献
7.
In this paper, we consider mixed H 2/H ∞ control problems for linear infinite-dimensional systems. The first part considers the state feedback control for the H 2/H ∞ control problems of linear infinite-dimensional systems. The cost horizon can be infinite or finite time. The solutions of the H 2/H ∞ control problem for linear infinitedimensional systems are presented in terms of the solutions of the coupled operator Riccati equations and coupled differential operator Riccati equations. The second part addresses the observer-based H 2/H ∞ control of linear infinite-dimensional systems with infinite horizon and finite horizon costs. The solutions for the observer-based H 2/H ∞ control problem of linear infinite-dimensional systems are represented in terms of the solutions of coupled operator Riccati equations. The first-order partial differential system examples are presented for illustration. In particular, for these examples, the Riccati equations are represented in terms of the coefficients of first-order partial differential systems. 相似文献
8.
Given an alphabet Σ={1,2,…,|Σ|} text string T∈Σ
n
and a pattern string P∈Σ
m
, for each i=1,2,…,n−m+1 define L
p
(i) as the p-norm distance when the pattern is aligned below the text and starts at position i of the text. The problem of pattern matching with L
p
distance is to compute L
p
(i) for every i=1,2,…,n−m+1. We discuss the problem for d=1,2,∞. First, in the case of L
1 matching (pattern matching with an L
1 distance) we show a reduction of the string matching with mismatches problem to the L
1 matching problem and we present an algorithm that approximates the L
1 matching up to a factor of 1+ε, which has an
O(\frac1e2nlogmlog|S|)O(\frac{1}{\varepsilon^{2}}n\log m\log|\Sigma|)
run time. Then, the L
2 matching problem (pattern matching with an L
2 distance) is solved with a simple O(nlog m) time algorithm. Finally, we provide an algorithm that approximates the L
∞ matching up to a factor of 1+ε with a run time of
O(\frac1enlogmlog|S|)O(\frac{1}{\varepsilon}n\log m\log|\Sigma|)
. We also generalize the problem of String Matching with mismatches to have weighted mismatches and present an O(nlog 4
m) algorithm that approximates the results of this problem up to a factor of O(log m) in the case that the weight function is a metric. 相似文献
9.
Chen-Ming Bai Zhi-Hui Li Jing-Tao Wang Cheng-Ji Liu Yong-Ming Li 《Quantum Information Processing》2018,17(11):312
In this work, we study a restricted (k, n)-threshold access structure. According to this structure, we construct a group of orthogonal multipartite entangled states in d-dimensional system and investigate the distinguishability of these entangled states under restricted local operations and classical communication. Based on these properties, we propose a restricted (k, n)-threshold quantum secret sharing scheme (called LOCC-QSS scheme). The k cooperating players in the restricted threshold scheme come from all disjoint groups. In the proposed protocol, the participants distinguish these orthogonal states by the computational basis measurement and classical communication to reconstruct the original secret. Furthermore, we also analyze the security of our scheme in three primary quantum attacks and give a simple encoding method in order to better prevent the participant conspiracy attack. 相似文献
10.
Sang-Eon Han 《Journal of Mathematical Imaging and Vision》2008,31(1):1-16
In order to discuss digital topological properties of a digital image (X,k), many recent papers have used the digital fundamental group and several digital topological invariants such as the k-linking number, the k-topological number, and so forth. Owing to some difficulties of an establishment of the multiplicative property of the digital
fundamental group, a k-homotopic thinning method can be essentially used in calculating the digital fundamental group of a digital product with
k-adjacency. More precisely, let
be a simple closed k
i
-curve with l
i
elements in
. For some k-adjacency of the digital product
which is a torus-like set, proceeding with the k-homotopic thinning of
, we obtain its k-homotopic thinning set denoted by DT
k
. Writing an algorithm for calculating the digital fundamental group of
, we investigate the k-fundamental group of
by the use of various properties of a digital covering (Z×Z,p
1×p
2,DT
k
), a strong k-deformation retract, and algebraic topological tools. Finally, we find the pseudo-multiplicative property (contrary to the
multiplicative property) of the digital fundamental group. This property can be used in classifying digital images from the
view points of both digital k-homotopy theory and mathematical morphology.
相似文献
Sang-Eon HanEmail: Email: |
11.
Mingzhe Hou Aiguo Wu Gunagren Duan 《International Journal of Control, Automation and Systems》2017,15(2):489-497
This paper presents a novel stochastic finite-time stability theorem and gives its application in the finite-time L 2?L ∞ filter design for nonlinear stochastic systems. Different form the frequently-used stochastic finite-time stability result, the proposed one does not require that all the states have the same fractional order exponent. Based on this result, a sufficient condition is given for nonlinear stochastic systems to possess the finite-time L 2?L ∞ performance with a prescribed gain. Further, an existence condition of the finite-time L 2?L ∞ filter with a prescribed disturbance attenuation level is given for nonlinear stochastic systems with external disturbance inputs. The effectiveness of the obtained results is illustrated by an example. 相似文献
12.
M. M. Kogan 《Automation and Remote Control》2016,77(8):1317-1333
For a double-input single-output system, this paper defines a disturbance attenuation level (called H∞/γ0 norm) as the maximum-value L2 norm of the output under an unknown disturbance with a bounded L2 norm supplied to the first input and an impulsive disturbance in the form of the product of an unknown vector and the delta function supplied the second input, where the squared L2 norm of the former disturbance plus the quadratic form of the impulsive disturbance vector does not exceed 1. Weight matrix choice in the H∞/γ0 norm yields a trade-off between the attenuation level of the L2 disturbance and the attenuation level of the impulsive disturbance in corresponding channels. For the uncertain systems with dynamic or parametric uncertainty in the feedback loop, a robust H∞/γ0 norm is introduced that includes the robust H∞ and γ0 norms as special cases. All these characteristics or their upper bounds in the uncertain system are expressed via solutions of linear matrix inequalities. This gives a uniform approach for designing optimal and robust control laws with the H∞/γ0, H∞ and γ0 performance criteria. 相似文献
13.
This paper investigates a hill type economic production-inventory quantity (EPIQ) model with variable lead-time, order size and reorder point for uncertain demand. The average expected cost function is formulated by trading off costs of lead-time, inventory, lost sale and partial backordering. Due to the nature of the demand function, the frequent peak (maximum) and valley (minimum) of the expected cost function occur within a specific range of lead time. The aim of this paper is to search the lowest valley of all the valley points (minimum objective values) under fuzzy stochastic demand rate. We consider Intuitionistic fuzzy sets for the parameters and used Intuitionistic Fuzzy Aggregation Bonferroni mean for the defuzzification of the hill type EPIQ model. Finally, numerical examples and graphical illustrations are made to justify the model. 相似文献
14.
Yanqian Wang Junwei Lu Ze Li Yuming Chu 《International Journal of Control, Automation and Systems》2016,14(3):655-665
In this paper, the mixed H 2/H ∞ control problem is investigated for a class of nonlinear discrete-time networked control systems with random network-induced delays, stochastic packet dropouts and probabilistic sensor faults. The packet dropouts process is modeled as a homogeneous Markov chains taking values in a finite state space. Network-induced delays occur in a random way with known upper bound. A set of stochastic variables are exploited to describe sensor faults with different probabilistic density functions. By using a delay-dependent Lyapunov functional, a mode-dependent mixed H 2/H ∞ controller is designed to guarantee both stochastic stability of the closed-loop system and the prescribed H2, H¥ control performances. Sufficient conditions for the existence of the mixed H 2/H ∞ controller are presented in terms of a series of LMIs. If these LMIs are feasible, then the modedependent mixed H 2/H ∞ controller can be obtained. A numerical example is given to demonstrate the effectiveness of the developed method. 相似文献
15.
The problem of mixed H2/H∞ filtering for polytopic Delta operator systems is investigated. The aim is to design a linear asymptotically stable filter which guarantees that the filtering error system has different performances in different filtering channels. Based on a parameter-dependent Lyapunov function, a new mixed H2/H∞ performance criterion is presented. Upon this performance criterion, a sufficient condition for the full-order mixed H2/H∞ filter is derived in terms of linear matrix inequalities. The filter can be obtained from the solution of a convex optimization problem. The proposed filter design procedure is less conservative than the strategy based on the quadratic stability notion. A numerical example is given to illustrate the feasibility of the proposed approach. 相似文献
16.
Sezgin Aygün Can Aktaş Pradyumn Kumar Sahoo Binaya K. Bishi 《Gravitation and Cosmology》2018,24(3):302-307
We study the behavior of cosmological parameters, massive and massless scalar fields (normal or phantom) with a scalar potential in f(R, T) theory of gravity for a flat Friedmann-Robertson-Walker (FRW) universe. To get exact solutions to the modified field equations, we use the f(R, T) = R + 2f(T) model by Harko et al. (T. Harko et al., Phys. Rev. D 84, 024020 (2011)), where R is the Ricci scalar and T is the trace of the energy momentum tensor. Our cosmological parameter solutions agree with the recent observational data. Finally, we discuss our results with various graphics. 相似文献
17.
Aminollah Mahabadi Hamid Sarbazi-Azad Ebrahim Khodaie Keivan Navi 《The Journal of supercomputing》2008,45(1):1-14
This paper proposes an efficient parallel algorithm for computing Lagrange interpolation on k-ary n-cube networks. This is done using the fact that a k-ary n-cube can be decomposed into n link-disjoint Hamiltonian cycles. Using these n link-disjoint cycles, we interpolate Lagrange polynomial using full bandwidth of the employed network. Communication in the
main phase of the algorithm is based on an all-to-all broadcast algorithm on the n link-disjoint Hamiltonian cycles exploiting all network channels, and thus, resulting in high-efficiency in using network
resources. A performance evaluation of the proposed algorithm reveals an optimum speedup for a typical range of system parameters
used in current state-of-the-art implementations.
相似文献
Hamid Sarbazi-AzadEmail: Email: |
18.
Guanglei Zhao Jingcheng Wang 《International Journal of Control, Automation and Systems》2011,9(4):777-784
This paper considers the problem of H
∞ dynamic output feedback (DOF) control for a class of stochastic systems with time-varying delay and L
∞ disturbance. A new delay-dependent sufficient condition for the existence of the DOF controller is derived and the controller
design method is given in the form of bilinear matrix inequalities (BMIs). Moreover, a variable step size path-following algorithm
is proposed to solve the BMI problem. Numerical examples are given to illustrate the effectiveness of the proposed methods. 相似文献
19.
Raymond Wong Jiuyong Li Ada Fu Ke Wang 《Journal of Intelligent Information Systems》2009,33(2):209-234
Privacy preservation is an important issue in the release of data for mining purposes. The k-anonymity model has been introduced for protecting individual identification. Recent studies show that a more sophisticated
model is necessary to protect the association of individuals to sensitive information. In this paper, we propose an (α, k)-anonymity model to protect both identifications and relationships to sensitive information in data. We discuss the properties
of (α, k)-anonymity model. We prove that the optimal (α, k)-anonymity problem is NP-hard. We first present an optimal global-recoding method for the (α, k)-anonymity problem. Next we propose two scalable local-recoding algorithms which are both more scalable and result in less
data distortion. The effectiveness and efficiency are shown by experiments. We also describe how the model can be extended
to more general cases. 相似文献
20.
After analyzing Yang’s verifiable quantum secret sharing (VQSS) scheme, we show that in their scheme a participant can prepare a false quantum particle sequence corresponding to a forged share, while other any participant cannot trace it. In addition, an attacker or a participant can forge a new quantum sequence by transforming an intercepted quantum sequence; moreover, the forged sequence can pass the verification of other participants. So we propose a new VQSS scheme to improve the existed one. In the improved scheme, we construct an identity-based quantum signature encryption algorithm, which ensures chosen plaintext attack security of the shares and their signatures transmitted in the quantum tunnel. We employ dual quantum signature and one-way function to trace against forgery and repudiation of the deceivers (dealer or participants). Furthermore, we add the reconstruction process of quantum secret and prove the security property against superposition attack in this process. 相似文献