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1.
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
2.
F. I. Solov’eva 《Problems of Information Transmission》2007,43(1):26-32
For any pair of integers r and m, 0 ≤ r ≤ m, we construct a class of quaternary linear codes whose binary images under the Gray map are codes with the parameters of the classical rth-order Reed-Muller code RM(r, m). 相似文献
3.
A. S. Ibraheam Y. Al-Douri J. M. S. Al-Fhdawi Hamid S. AL-Jumaili K. D. Verma U. Hashim R. M. Ayub A. Rahim Ruslinda M. K. Md Arshad A. H. Reshak S. B. Abd Hamid 《Microsystem Technologies》2016,22(12):2893-2900
The Cu2Zn1?xCdxSnS4 quinternary alloy nanostructures with different Cd contents were grown using spin coating technique on porous silicon (63.93 %) substrate. The structural properties of Cu2Zn1?xCdxSnS4/PS were investigated by X-ray diffraction and field emission-scanning electron microscope (FE-SEM). The optical properties studied through photoluminescence technique, indicated that the band gap is shifted as Cd content increases from 1.84 eV at x = 0 to 1.76 eV at x = 1. The electrical characterization of the Ag/n-PS/Cu2Zn1?xCdxSnS4/Ag diode through current to voltage (I–V) characterization shows the highest photo-response of (value if any) at Cu2Zn0.4Cd0.6SnS4 composition. 相似文献
4.
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
5.
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
6.
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
7.
For linear plants with unstructured or structured uncertainty of bounded norm, this paper designs Pareto optimal robust controllers in terms of linear matrix inequalities in multicriteria control problems with the generalized H2 or γ0 norms. The controller design procedure is based on optimization of a scalar objective function (Germeier convolution) and semi-definite programming. The developed theory is used to design multicriteria robust controllers in the stabilization problem for a rotor in electromagnetic bearings. 相似文献
8.
Consideration was given to the design of discrete dynamic reduced-order controllers minimizing the ℋ2-norm of the transfer matrix of a closed-loop system. The problem of reducing the controller order is related to the solution
of the singular problem of filtration (no measurement noise) and control (no control at the controlled output). Using the
well-known structures of controllers based on the corresponding minimum-order observers, these problems were shown to be reducible
to the solution of two Riccati equations of which one is of a reduced order. Peculiarities of solution that are characteristic
of the digital controllers and caused by the allowance for astatism and presence of control delays were examined. An example
of an ℋ2-optimal reduced-order controller was presented to illustrate the results obtained. 相似文献
9.
A new paradigm for processing signals with sparse representation in some basis is actively developed for some time past. It relies largely on the ideas of measurement randomization and ℓ1-optimization. The recent methods of acquisition and representation of the compressed data were christened compressive sensing. 相似文献
10.
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
11.
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
12.
N. N. Tokareva 《Problems of Information Transmission》2005,41(2):113-124
A binary code is called ℤ4-linear if its quaternary Gray map preimage is linear. We show that the set of all quaternary linear Preparata codes of length n = 2m, m odd, m ≥ 3, is nothing more than the set of codes of the form
with
where T
λ(⋅) and S
ψ (⋅) are vector fields of a special form defined over the binary extended linear Hamming code H
n
of length n. An upper bound on the number of nonequivalent quaternary linear Preparata codes of length n is obtained, namely,
. A representation for binary Preparata codes contained in perfect Vasil’ev codes is suggested.__________Translated from Problemy Peredachi Informatsii, No. 2, 2005, pp. 50–62.Original Russian Text Copyright © 2005 by Tokareva.Supported in part by the Ministry of Education of the Russian Federation program “Development of the Scientific Potential of the Higher School,” project no. 512. 相似文献
13.
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
14.
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
15.
Wei Wang Huanshui Zhang Chunyan Han 《International Journal of Control, Automation and Systems》2010,8(6):1159-1170
The problem of H
∞ filtering for discrete-time systems with time-varying delay in measurement is investigated in this paper. First, under the
assumption that the time-varying delay is of a known upper bound, the delayed measurement is re-described as the one with
multiple state delays. Then the proposed H
∞ filtering problem is transformed into one for systems with multiple measurement channels that contain the same state information
as the original measurement and each channel has a single constant delay. Finally, based on the reorganized innovation analysis
approach in Krein space, a necessary and sufficient condition for the existence of an H
∞ filter which guarantees a prescribed attenuation level is derived. The solution to the H
∞ filtering is given in terms of the solutions to Riccati and matrix difference equations. 相似文献
16.
17.
In this paper, the state-feedback Nash game based mixed H2/H∞ design[1, 2] has been extended for output feedback case. The algorithm is applied to control bioreactor system with a Laguerre-Wavelet Network (LWN)[3, 4] model of the bioreactor. This is achieved by using the LWN model as a deviation model and by successively linearising the deviation model along the state trajectory. For reducing the approximation error and to improve the controller performance, symbolic derivation algorithm, viz., automatic differentiation is employed. A cautionary note is also given on the fragility of the output feedback mixed H2/H∞ model predictive controller[4, 5] due to its sensitivity to its own parametric changes. 相似文献
18.
R. Blanch-Ojea R. M. Tiggelaar J. Pallares F. X. Grau J. G. E. Gardeniers 《Microfluidics and nanofluidics》2012,12(6):927-940
In this work, an experimental investigation of the single- and multiphase flows of two sets of fluids, CO2–ethanol and CO2–methanol, in a non-adiabatic microfluidic T-junction is presented. The operating conditions ranged from 7 to 18 MPa, and from 294 to 474 K. The feed mass fraction of CO2 in the mixtures was 0.95 and 0.87, respectively. Under these operating conditions, CO2 was either in liquid, gas or supercritical state; and the mixtures experienced a miscible single phase or a vapour–liquid equilibrium (VLE), with two separated phases. Taylor, annular and wavy were the two-phase flow regimes obtained in the VLE region. In the single phase region, the observed flows were classified into standard single-phase flows, “pseudo” two-phase flows and local phenomena in the T-junction. Flow regime maps were generated, based on temperature and pressure conditions. Two-phase flow void fractions and several parameters of Taylor flow were analysed. They showed a clear dependency on temperature, but were mostly insensitive to pressure. A continuous accumulation of liquid, either in the CO2 channel or at the CO2-side wall after the T-junction, disturbed most of the experiments in VLE conditions by randomly generating liquid plugs. This phenomenon is analysed, and capillary and wetting effects due to local Marangoni stresses are suggested as possible causes. 相似文献
19.
Jiemei Zhao Zhonghui Hu 《International Journal of Control, Automation and Systems》2017,15(4):1592-1599
This paper studies the exponential admissibility and H ∞ control problems for a class of singular systems with time-varying delay in state. Firstly, an exponential admissibility criterion is obtained based on linear matrix inequalities (LMIs). It is worth mentioning that the derivative of the time-varying delay does not need to be smaller than one. Based on the proposed condition, a new delay-dependent H ∞ controller is also given, which guarantees the admissibility and the H ∞ performance γ. Numerical examples are given to illustrate the effectiveness of the proposed method. 相似文献
20.
In this paper, robust H 2 and H ∞ control problems for discrete linear time-invariant (LTI) systems with polytopic uncertainties are addressed. The so-called finite impulse response (FIR) controller incorporating the states over several samples from the past to the present is adopted to design robust control laws with improved performances. For the closed-loop stability, parameter-dependent quadratic Lyapunov functions (PD-QLFs) are employed. Sufficient controller synthesis conditions are derived in the form of linear matrix inequalities (LMIs). Finally, examples are given to demonstrate the usefulness of the proposed methods. 相似文献