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61.
Paul Beaucaire Nicolas Gayton Emmanuel Duc Maurice Lemaire Jean-Yves Dantan 《Computers & Industrial Engineering》2012
The quality level of a mechanism can be evaluated a posteriori after several months by following the number of warranty returns. However, it is more interesting to evaluate a predicted quality level in the design stage: this is one of the aims of statistical tolerance analysis. A possible method consists of computing the defect probability (PD) expressed in ppm. It represents the probability that a functional requirement will not be satisfied in mass production. For assembly reasons, many hyperstatic mechanisms require gaps, which their functional requirements depend on. The defect probability assessment of such mechanisms is not straightforward, and requires advanced numerical methods. This problem particularly interests the VALEO W.S. company, which experiences problems with an assembly containing gaps. This paper proposes an innovative methodology to formulate and compute the defect probability of hyperstatic mechanisms with gaps in two steps. First, a complex feasibility problem is converted into a simpler problem. Then the defect probability is efficiently computed thanks to system reliability methods and the m-dimensional multivariate normal distribution Φm. Finally, a sensitivity analysis is provided to improve the original design. The whole approach is illustrated with an industrial case study, but can be adapted to other similar problems. 相似文献
62.
Flavio P. Junqueira Keith Marzullo Maurice Herlihy Lucia Draque Penso 《Distributed Computing》2010,23(2):135-149
Many replication protocols employ a threshold model when expressing failures they are able to tolerate. In this model, one assumes that no more than t out of n components can fail, which is a good representation when failures are independent and identically distributed (IID). In many real systems, however, failures are not IID, and a straightforward application of threshold protocols yields suboptimal results. Here, we examine the problem of transforming threshold protocols into survivor-set protocols tolerating dependent failures. Our main goal is to show the equivalence between the threshold model and the core/survivor set model. Toward this goal, we develop techniques to transform threshold protocols into survivor set ones. Our techniques do not require authentication, self-verification or encryption. Our results show in one case that we can transform a threshold protocol to a subset by spreading a number of processes across processors. This technique treats a given threshold algorithm as a black box, and consequently can transform any threshold algorithm. However, it has the disadvantage that the transformation is not possible for all sets of survivor sets. The second technique instead focuses on transforming voters: functions that evaluate to a value out of a set of tallied values in a replication protocol. Voters are an essential part of many fault-tolerant protocols, and we show a universal way of transforming them. With such a transformation we expect that a large number of protocols in the literature can be directly transformed with our technique. It is still an open problem, however, if the two models are equivalent, and our results constitute an important first step in this direction. 相似文献
63.
64.
Jan Ramon Tom Croonenborghs Daan Fierens Hendrik Blockeel Maurice Bruynooghe 《Machine Learning》2008,70(2-3):169-188
Recently, there has been an increasing interest in directed probabilistic logical models and a variety of formalisms for describing
such models has been proposed. Although many authors provide high-level arguments to show that in principle models in their
formalism can be learned from data, most of the proposed learning algorithms have not yet been studied in detail. We introduce
an algorithm, generalized ordering-search, to learn both structure and conditional probability distributions (CPDs) of directed
probabilistic logical models. The algorithm is based on the ordering-search algorithm for Bayesian networks. We use relational
probability trees as a representation for the CPDs. We present experiments on a genetics domain, blocks world domains and
the Cora dataset.
Editors: Stephen Muggleton, Ramon Otero, Simon Colton. 相似文献
65.
Ricardo G. Sanfelice J.J. Benjamin Biemond Nathan van de Wouw W.P.Maurice H. Heemels 《国际强度与非线性控制杂志
》2014,24(11):1585-1608
》2014,24(11):1585-1608
We study the problem of designing state‐feedback controllers to track time‐varying state trajectories that may exhibit jumps. Both plants and controllers considered are modeled as hybrid dynamical systems, which are systems with both continuous and discrete dynamics, given in terms of a flow set, a flow map, a jump set, and a jump map. Using recently developed tools for the study of stability in hybrid systems, we recast the tracking problem as the task of asymptotically stabilizing a set, the tracking set, and derive conditions for the design of state‐feedback tracking controllers with the property that the jump times of the plant coincide with those of the given reference trajectories. The resulting tracking controllers guarantee that solutions of the plant starting close to the reference trajectory stay close to it and that the difference between each solution of the controlled plant and the reference trajectory converges to zero asymptotically. Constructive conditions for tracking control design in terms of LMIs are proposed for a class of hybrid systems with linear maps and input‐triggered jumps. The results are illustrated by various examples. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
66.
Giuditta Franco Maurice Margenstern 《Electronic Notes in Theoretical Computer Science》2007,171(2):15
We propose a biologically inspired system which computes on double structures of mobile strings by means of rewriting rules that have a biotechnological implementation, by resembling DNA computations. Its computational universality may be straight deduced from a few formal language theoretical results of one of the authors. Such a DNA-like computational device is naturally described by a membrane system which concludes the paper. 相似文献
67.
In this paper two different approaches to the design of a reconfigurable Tate pairing hardware accelerator are presented. The first uses macro components based on a large, fixed number of underlying Galois Field arithmetic units in parallel to minimise the computation time. The second is an area efficient approach based on a small, variable number of underlying components. Both architectures are prototyped on an FPGA. Timing results for each architecture with various different design parameters are presented. 相似文献
68.
Ofer Arieli Marc Denecker Maurice Bruynooghe 《Annals of Mathematics and Artificial Intelligence》2007,50(3-4):389-415
In many scenarios, a database instance violates a given set of integrity constraints. In such cases, it is often required
to repair the database, that is, to restore its consistency. A primary motif behind the repairing approaches is the principle of minimal change, which is the aspiration to keep the recovered data as faithful as possible to the original (inconsistent) database. In this
paper, we represent this qualitative principle quantitatively, in terms of distance functions and some underlying metrics,
and so introduce a general framework for repairing inconsistent databases by distance-based considerations. The uniform way
of representing repairs and their semantics clarifies the essence behind several approaches to consistency restoration in
database systems, helps to compare the underlying formalisms, and relates them to existing methods of defining belief revision
operators, merging data sets, and integrating information systems.
相似文献
69.
Xavier Maurice Anders Sandholm Nicolas Pronost Ronan Boulic Daniel Thalmann 《The Visual computer》2009,25(9):835-842
Today, to create and to simulate a virtual anatomical version of a subject is useful in the decision process of surgical treatments.
The muscular activity is one of the factors which can contribute to abnormal movements such as in spasticity or static contracture.
In this paper, we propose a numerical solution, based on the Finite Element (FE) method, able to estimate muscles deformations
during contraction. Organized around a finite element solver and a volumetric environment, this solution is made of all the
modeling and simulation processes from the discretization of the studied domain to the visualization of the results. The choices
of materials and properties of the FE model are also presented such as the hyperelasticity, the contention model based on
inter-meshes neighboring nodes pairing, and the estimation of nodal forces based on the subject-specific muscular forces and
action lines.
相似文献
Nicolas PronostEmail: |
70.
Synchronizations in Team Automata for Groupware Systems 总被引:7,自引:0,他引:7
Maurice H. ter Beek Clarence A. Ellis Jetty Kleijn Grzegorz Rozenberg 《Computer Supported Cooperative Work (CSCW)》2003,12(1):21-69
Team automata have been proposed in Ellis (1997) as a formal framework for modeling both the conceptual and the architectural level of groupware systems. Here we define team automata in a mathematically precise way in terms of component automata which synchronizeon certain executions of actions.At the conceptual level, our model serves as a formal framework in whichbasic groupware notions can be rigorously defined and studied.At the architectural level, team automata can be used as building blocksin the design of groupware systems. 相似文献