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排序方式: 共有3477条查询结果,搜索用时 31 毫秒
91.
This article deals with a local improvement of domain decomposition methods for 2-dimensional elliptic problems for which
either the geometry or the domain decomposition presents conical singularities. After explaining the main results of the theoretical
analysis carried out in Chniti et al. (Calcolo 45, 2008), the numerical experiments presented in this article confirm the optimality properties of the new interface conditions. 相似文献
92.
In this study, an optimization of the airfoil of a sailplane is carried out by a recently developed multi-objective genetic algorithm based on microevolution, containing crowding, range adaptation, knowledge-based reinitialization and ε-dominance. Its efficiency was tested on a set of test problems. The results are encouraging, suggesting that very small populations can be used effectively to solve real-world multi-objective optimization problems in many cases of interest. 相似文献
93.
Interval state observers provide an estimate on the set of admissible values of the state vector at each instant of time. Ideally, the size of the evaluated set is proportional to the model uncertainty, thus interval observers generate the state estimates with estimation error bounds, similarly to Kalman filters, but in the deterministic framework. Main tools and techniques for design of interval observers are reviewed in this tutorial for continuous-time, discrete-time and time-delayed systems. 相似文献
94.
This paper addresses the problem of interval observer design for unknown input estimation in linear time-invariant systems. Although the problem of unknown input estimation has been widely studied in the literature, the design of joint state and unknown input observers has not been considered within a set-membership context. While conventional interval observers could be used to propagate with some additional conservatism, unknown inputs by considering them as disturbances, the proposed approach allows their estimation. Under the assumption that the measurement noise and the disturbances are bounded, lower and upper bounds for the unmeasured state and unknown inputs are computed. Numerical simulations are presented to show the efficiency of the proposed approach. 相似文献
95.
Fatih Çalışır Muhammet Baştan Özgür Ulusoy Uğur Güdükbay 《Multimedia Tools and Applications》2017,76(10):12433-12456
High user interaction capability of mobile devices can help improve the accuracy of mobile visual search systems. At query time, it is possible to capture multiple views of an object from different viewing angles and at different scales with the mobile device camera to obtain richer information about the object compared to a single view and hence return more accurate results. Motivated by this, we propose a new multi-view visual query model on multi-view object image databases for mobile visual search. Multi-view images of objects acquired by the mobile clients are processed and local features are sent to a server, which combines the query image representations with early/late fusion methods and returns the query results. We performed a comprehensive analysis of early and late fusion approaches using various similarity functions, on an existing single view and a new multi-view object image database. The experimental results show that multi-view search provides significantly better retrieval accuracy compared to traditional single view search. 相似文献
96.
This paper presents a method of state estimation for uncertain nonlinear systems described by multiple models approach. The uncertainties, supposed as norm bounded type, are caused by some parameters’ variations of the nonlinear system. Linear matrix inequalities (LMIs) have been established in order to ensure the stability conditions of the multiple observer which lead to determine the estimation gains. A sliding mode gain has been added in order to compensate the uncertainties. Numerical simulations through a state space model of a real process have been realized to show the robustness of the synthesized observer. 相似文献
97.
Simultaneous automated design of structured QFT controller and prefilter using nonlinear programming 下载免费PDF全文
Harsh Purohit Alexandre Goldsztejn Christophe Jermann Laurent Granvilliers Frédéric Goualard P. S. V. Nataraj Bhagyesh Patil 《国际强度与非线性控制杂志
》2017,27(15):2529-2548
》2017,27(15):2529-2548
This paper describes a nonlinear programming‐based robust design methodology for controllers and prefilters of a predefined structure for the linear time‐invariant systems involved in the quantitative feedback theory. This controller and prefilter synthesis problem is formulated as a single optimization problem with a given performance optimization objective and constraints enforcing stability and various specifications usually enforced in the quantitative feedback theory. The focus is set on providing constraints expression that can be used in standard nonlinear programming solvers. The nonlinear solver then computes in a single‐step controller and prefilter design parameters that satisfy the prescribed constraints and maximizes the performance optimization objective. The effectiveness of the proposed approach is demonstrated through a variety of difficult design cases like resonant plants, open‐loop unstable plants, and plants with variation in the time delay. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
98.
Frédéric Havet Martin Klazar Jan Kratochvíl Dieter Kratsch Mathieu Liedloff 《Algorithmica》2011,59(2):169-194
The notion of distance constrained graph labelings, motivated by the Frequency Assignment Problem, reads as follows: A mapping
from the vertex set of a graph G=(V,E) into an interval of integers {0,…,k} is an L(2,1)-labeling of G of span k if any two adjacent vertices are mapped onto integers that are at least 2 apart, and every two vertices with a common neighbor
are mapped onto distinct integers. It is known that for any fixed k≥4, deciding the existence of such a labeling is an NP-complete problem. We present exact exponential time algorithms that
are faster than the naive O
*((k+1)
n
) algorithm that would try all possible mappings. The improvement is best seen in the first NP-complete case of k=4, where the running time of our algorithm is O(1.3006
n
). Furthermore we show that dynamic programming can be used to establish an O(3.8730
n
) algorithm to compute an optimal L(2,1)-labeling. 相似文献
99.
Frédéric Cuppens Nora Cuppens-Boulahia 《International Journal of Information Security》2008,7(4):285-305
As computer infrastructures become more complex, security models must provide means to handle more flexible and dynamic requirements.
In the Organization Based Access Control (OrBAC) model, it is possible to express such requirements using the notion of context.
In OrBAC, each security rule (permission, prohibition, obligation or dispensation) only applies in a given context. A context
is viewed as an extra condition that must be satisfied to activate a given security rule. In this paper, we present a taxonomy
of different types of context and investigate the data the information system must manage in order to deal with these different
contexts. We then explain how to model and evaluate them in the OrBAC model.
相似文献
Nora Cuppens-BoulahiaEmail: |
100.
Frédéric Mallet 《Innovations in Systems and Software Engineering》2008,4(3):309-314
The Object Management Group (OMG) unified modeling language (UML) profile for modeling and analysis of real-time and embedded
systems (MARTE) aims at using the general-purpose modeling language UML in the domain of real-time and embedded (RTE) systems.
To achieve this goal, it is absolutely required to introduce inside the mainly untimed UML an unambiguous time structure which
MARTE model elements can rely on to build precise models amenable to formal analysis. The MARTE Time model has defined such
a structure. We have also defined a non-normative concrete syntax called the clock constraint specification language (CCSL)
to demonstrate what can be done based on this structure. This paper gives a brief overview of this syntax and its formal semantics,
and shows how existing UML model elements can be used to apply this syntax in a graphical way and benefit from the semantics. 相似文献