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101.
Peter A.C. Varley Author Vitae Pedro P. Company Author Vitae 《Computer aided design》2010,42(4):279-309
The problem of identifying the topology implied by wireframe drawings of polyhedral objects requires the identification of face loops, loops of edges which correspond to a face in the object the drawing portrays.In this paper, we survey the advantages and limitations of known approaches, and present and discuss test results which illustrate the successes and failures of a currently popular approach based on Dijkstra’s Algorithm. We conclude that the root cause of many failure cases is that the underlying algorithm assumes that the cost of traversing an edge is fixed.We propose a new polynomial-order algorithm for finding faces in wireframes. This algorithm could be adapted to any graph-theoretical least-cost circuit problem where the cost of traversing an edge is not fixed but context-dependent. 相似文献
102.
Pedro Casas Lionel Fillatre Sandrine Vaton Igor Nikiforov 《Journal of Network and Systems Management》2011,19(1):58-83
This paper presents a novel approach to deal with dynamic and highly uncertain traffic in dynamic network scenarios. The Reactive
Robust Routing (RRR) approach is introduced, a combination of proactive and reactive techniques to improve network efficiency
and robustness, simplifying network operation. RRR optimizes routing for normal-operation traffic, using a time-varying extension
of the already established Robust Routing technique that outperforms the stable approach. To deal with anomalous and unexpected
traffic variations, RRR uses a fast anomaly detection and localization algorithm that rapidly detects and localizes abrupt
changes in traffic flows, permitting an accurate routing adaptation. This algorithm presents well-established optimality properties
in terms of detection/localization rates and localization delay, which allows for generalization of results, independently
of particular evaluations. The algorithm is based on a novel parsimonious model for traffic demands which allows for detection
of anomalies using easily available aggregated-traffic measurements, reducing the overheads of data collection. 相似文献
103.
Javier Sánchez-Monedero Pedro A. Gutiérrez F. Fernández-Navarro C. Hervás-Martínez 《Neural Processing Letters》2011,34(2):101-116
Recently, a multi-objective Sensitivity–Accuracy based methodology has been proposed for building classifiers for multi-class problems. This technique is especially suitable for imbalanced and multi-class datasets. Moreover, the high computational cost of multi-objective approaches is well known so more efficient alternatives must be explored. This paper presents an efficient alternative to the Pareto based solution when considering both Minimum Sensitivity and Accuracy in multi-class classifiers. Alternatives are implemented by extending the Evolutionary Extreme Learning Machine algorithm for training artificial neural networks. Experiments were performed to select the best option after considering alternative proposals and related methods. Based on the experiments, this methodology is competitive in Accuracy, Minimum Sensitivity and efficiency. 相似文献
104.
Fredrik Larsson Pedro Díez Antonio Huerta 《Computer Methods in Applied Mechanics and Engineering》2010,199(37-40):2383-2402
In this contribution, we present an a posteriori error estimator for the incompressible Stokes problem valid for a conventional mixed FE formulation. Due to the saddle-point property of the problem, conventional error estimators developed for pure minimization problems cannot be utilized straight-forwardly. The new estimator is built up by two key ingredients. At first, a computed error approximation, exactly fulfilling the continuity equation for the error, is obtained via local Dirichlet problems. Secondly, we adopt the approach of solving local equilibrated flux-free problems in order to bound the remaining, incompressible, error. In this manner, guaranteed upper and lower bounds, of the velocity “energy norm” of the error as well as goal-oriented (linear) output functionals, with respect to a reference (overkill) mesh are obtained. In particular, it should be noted that this approach requires no computation of hybrid fluxes. Furthermore, the estimator is applicable to mixed FE formulations using continuous pressure approximations, such as the Mini and Taylor–Hood class of elements. In conclusion, a few simple numerical examples are presented, illustrating the accuracy of the error bounds. 相似文献
105.
The problem of nonparametrically predicting a scalar response variable from a functional predictor is considered. A sample of pairs (functional predictor and response) is observed. When predicting the response for a new functional predictor value, a semi-metric is used to compute the distances between the new and the previously observed functional predictors. Then each pair in the original sample is weighted according to a decreasing function of these distances. A Weighted (Linear) Distance-Based Regression is fitted, where the weights are as above and the distances are given by a possibly different semi-metric. This approach can be extended to nonparametric predictions from other kinds of explanatory variables (e.g., data of mixed type) in a natural way. 相似文献
106.
107.
Shape optimized design of microwave dielectric resonators by level‐set and topology gradient methods
H. Khalil S. Bila M. Aubourg D. Baillargeat S. Verdeyme F. Jouve C. Delage T. Chartier 《国际射频与微波计算机辅助工程杂志》2010,20(1):33-41
The finite element method is coupled with the topology gradient (TG) and level‐set (LS) methods for optimizing the shape of microwave components using a computer‐aided design model. On the one hand, the LS approach is based on the classical shape derivative; while on the other hand, the TG method is precisely designed for introducing new perturbations in the optimization domain. These two approaches, which consist in minimizing a cost function related to the component behavior, are first described. Regarding given electrical specifications, these techniques are applied to optimize the distribution of ceramic parts of a dual‐mode resonator in order to improve its behavior. The optimized dielectric resonators result in a wide spurious‐free stop band. A comparison between classical and optimized dual mode resonator is presented. Theoretical results are then validated by careful measurements. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010. 相似文献
108.
Oliver Schreer Ingo Feldmann Isabel Alonso Mediavilla Pedro Concejero Abdul H. Sadka Mohammad Rafiq Swash Sergio Benini Riccardo Leonardi Tijana Janjusevic Ebroul Izquierdo 《Multimedia Tools and Applications》2010,48(1):23-49
Multimedia analysis and reuse of raw un-edited audio visual content known as rushes is gaining acceptance by a large number
of research labs and companies. A set of research projects are considering multimedia indexing, annotation, search and retrieval
in the context of European funded research, but only the FP6 project RUSHES is focusing on automatic semantic annotation,
indexing and retrieval of raw and un-edited audio-visual content. Even professional content creators and providers as well
as home-users are dealing with this type of content and therefore novel technologies for semantic search and retrieval are
required. In this paper, we present a summary of the most relevant achievements of the RUSHES project, focusing on specific
approaches for automatic annotation as well as the main features of the final RUSHES search engine. 相似文献
109.
We present in this paper an analysis of a semi-Lagrangian second order Backward Difference Formula combined with hp-finite
element method to calculate the numerical solution of convection diffusion equations in ℝ2. Using mesh dependent norms, we prove that the a priori error estimate has two components: one corresponds to the approximation
of the exact solution along the characteristic curves, which is
O(Dt2+hm+1(1+\frac\mathopen|logh|Dt))O(\Delta t^{2}+h^{m+1}(1+\frac{\mathopen{|}\log h|}{\Delta t})); and the second, which is O(Dtp+|| [(u)\vec]-[(u)\vec]h||L¥)O(\Delta t^{p}+\| \vec{u}-\vec{u}_{h}\|_{L^{\infty}}), represents the error committed in the calculation of the characteristic curves. Here, m is the degree of the polynomials in the finite element space, [(u)\vec]\vec{u} is the velocity vector, [(u)\vec]h\vec{u}_{h} is the finite element approximation of [(u)\vec]\vec{u} and p denotes the order of the method employed to calculate the characteristics curves. Numerical examples support the validity
of our estimates. 相似文献
110.