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排序方式: 共有1677条查询结果,搜索用时 15 毫秒
31.
Sergei V. Gusev Anton S. Shiriaev Leonid B. Freidovich 《International journal of control》2016,89(7):1396-1405
Numerically finding stabilising feedback control laws for linear systems of periodic differential equations is a nontrivial task with no known reliable solutions. The most successful method requires solving matrix differential Riccati equations with periodic coefficients. All previously proposed techniques for solving such equations involve numerical integration of unstable differential equations and consequently fail whenever the period is too large or the coefficients vary too much. Here, a new method for numerical computation of stabilising solutions for matrix differential Riccati equations with periodic coefficients is proposed. Our approach does not involve numerical solution of any differential equations. The approximation for a stabilising solution is found in the form of a trigonometric polynomial, matrix coefficients of which are found solving a specially constructed finite-dimensional semidefinite programming (SDP) problem. This problem is obtained using maximality property of the stabilising solution of the Riccati equation for the associated Riccati inequality and sampling technique. Our previously published numerical comparisons with other methods shows that for a class of problems only this technique provides a working solution. Asymptotic convergence of the computed approximations to the stabilising solution is proved below under the assumption that certain combinations of the key parameters are sufficiently large. Although the rate of convergence is not analysed, it appeared to be exponential in our numerical studies. 相似文献
32.
This work introduces a new algorithm for surface reconstruction in ℝ3 from spatially arranged one-dimensional cross sections embedded in ℝ3. This is generally the case with acoustic signals that pierce an object non-destructively. Continuous deformations (homotopies)
that smoothly reconstruct information between any pair of successive cross sections are derived. The zero level set of the
resulting homotopy field generates the desired surface. Four types of homotopies are suggested that are well suited to generate
a smooth surface. We also provide derivation of necessary higher order homotopies that can generate a C
2 surface. An algorithm to generate surface from acoustic sonar signals is presented with results. Reconstruction accuracies
of the homotopies are compared by means of simulations performed on basic geometric primitives. 相似文献
33.
This paper studies the so‐called inverse filtering and deconvolution problem from different angles. To start with, both exact and almost deconvolution problems are formulated, and the necessary and sufficient conditions for their solvability are investigated. Exact and almost deconvolution problems seek filters that can estimate the unknown inputs of the given plant or system either exactly or almostly whatever may be the unintended or disturbance inputs such as measurement noise, external disturbances, and model uncertainties that act on the system. As such they require strong solvability conditions. To alleviate this, several optimal and suboptimal deconvolution problems are formulated and studied. These problems seek filters that can estimate the unknown inputs of the given system either exactly, almostly or optimally in the absence of unintended (disturbance) inputs, and on the other hand, in the presence of unintended (disturbance) inputs, they seek that the influence of such disturbances on the estimation error be as small as possible in a certain norm (H2 or H∞) sense. Both continuous‐ and discrete‐time systems are considered. For discrete‐time systems, the counter parts of all the above problems when an ??‐step delay in estimation is present are introduced and studied. Next, we focus on the exact and almost deconvolution but this time when the uncertainties in plant dynamics can be structurally modeled by a Δ‐block as a feedback element to the nominally known plant dynamics. This is done either in the presence or absence of external disturbances. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
34.
Eremeev AV 《Evolutionary computation》2008,16(1):127-147
We consider the optimization problem of finding the best possible offspring as a result of a recombination operator in an evolutionary algorithm, given two parent solutions. The optimal recombination is studied in the case where a vector of binary variables is used as a solution encoding. By means of efficient reductions of the optimal recombination problems (ORPs) we show the polynomial solvability of the ORPs for the maximum weight set packing problem, the minimum weight set partition problem, and for linear Boolean programming problems with at most two variables per inequality, and some other problems. We also identify several NP-hard cases of optimal recombination: the Boolean linear programming problems with three variables per inequality, the knapsack, the set covering, the p-median, and some other problems. 相似文献
35.
In this paper we survey our research on smart meeting rooms and its relevance for augmented reality meeting support and virtual
reality generation of meetings in real time or off-line. The research reported here forms part of the European 5th and 6th
framework programme projects multi-modal meeting manager (M4) and augmented multi-party interaction (AMI). Both projects aim
at building a smart meeting environment that is able to collect multimodal captures of the activities and discussions in a
meeting room, with the aim to use this information as input to tools that allow real-time support, browsing, retrieval and
summarization of meetings. Our aim is to research (semantic) representations of what takes place during meetings in order
to allow generation, e.g. in virtual reality, of meeting activities (discussions, presentations, voting, etc.). Being able
to do so also allows us to look at tools that provide support during a meeting and at tools that allow those not able to be
physically present during a meeting to take part in a virtual way. This may lead to situations where the differences between
real meeting participants, human-controlled virtual participants and (semi-) autonomous virtual participants disappear.
相似文献
Dirk HeylenEmail: |
36.
A rapid method of oxymyoglobin purification 总被引:1,自引:0,他引:1
Oxymyoglobin was isolated from bovine Longissimus lumborum muscle by precipitation with ammonium sulfate and purification in rapid conditions with only one chromatographic step on Mono-Q HR column with a HPLC system. Purity of oxymyoglobin was controlled by SDS-polyacrylamide gel electrophoresis and isoelectrofocusing. 相似文献
37.
In this paper, we study simultaneous external and internal stabilization of the linear system under input saturation and non-input additive sustained disturbances. For systems that are asymptotic null controllable with bounded control, it is shown that a nonlinear dynamic feedback controller can be designed so that the closed-loop states remain bounded for any initial condition and for two classes of sustained disturbances, and that the equilibrium in the absence of disturbances is globally asymptotically stable. 相似文献
38.
Zusammenstellung von Schrifttumsangaben für die Änderung der freien Standardenthalpien der Reaktionen , Mo + O2 ? MoO2 und in Eisenschmelzen. Neubestimmung der Temperaturabhängigkeiten der Größen ΔGoCr2O3, ΔGoMoO2 und ΔGoO im Eisen bei Temperaturen zwischen 1460 bzw. 1530 und 1725 °C. Nachweis der Anwendbarkeit der neu ermittelten thermodynamischen Funktionen durch EMK-Parallelmessungen an ThO2 (Y2O3)- und ZrO2 (MgO)-Festelektrolytzellen mit Cr-Cr2O3- und Mo-MoO2-Referenzelektroden in Reineisenschmelzen bei 1600 °C. Ermittlung des Parameters pe′ der Elektronenteilleitfähigkeit für einen teilstabilisierten ZrO2-Festelektrolyten mit einem Stoffmengengehalt von 5% MgO. 相似文献
39.
Anton Evgrafov Michael Patriksson 《International journal for numerical methods in engineering》2005,64(1):17-44
We consider structural topology optimization problems including unilateral constraints arising from non‐penetration conditions in contact mechanics. The resulting non‐convex non‐smooth problems are instances of mathematical programs with equilibrium constraints (MPEC), or bi‐level programs. Applying nested (implicit programming) algorithms to this class of problems is problematic owing to the singularity of the feasible set. We propose a perturbation strategy combining the relaxation of the equilibrium constraint with the restriction of the design domain to its regular part only. This strategy allows us to attack the problem numerically using standard non‐linear programming algorithms. We rigorously study the optimality conditions for the original singular problem as well as the convergence of stationary points and globally optimal solutions to approximating problems towards respective stationary points and globally optimal solutions to the original problem. A limited numerical benchmarking of the algorithm is performed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
40.
Discrete‐time output regulation of linear systems with state and/or input constraints on magnitude is considered. Structural properties of linear plants are identified under which the so‐called constrained semi‐global and global output regulation problems are solvable. As in the case of continuous‐time systems, an important aspect of our development is a taxonomy of constraints showing a clear relationship between the constraint types and the output regulation results. Solvability conditions are developed for semi‐global and global output regulation problems. Appropriate regulators are constructed for problems that are solvable. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献