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31.
Antonio de la Oliva Ignacio Soto Albert Banchs Johannes Lessmann Christian Niephaus Telemaco MeliaAuthor vitae 《Computer Standards & Interfaces》2011,33(6):556-564
The IEEE 802.21 standard facilitates media independent handovers by providing higher layer mobility management functions with common service primitives for all technologies. Right after the base specification was published, several voices rose up in the working group advocating to broaden the scope of IEEE 802.21 beyond handovers. This paper aims at updating the reader with the main challenges and functionalities required to create a Media Independence Service Layer, through the analysis of scenarios which are being discussed within the working group: 1) Wireless Coexistence, and 2) Heterogeneous Wireless Multihop Backhaul Networks. 相似文献
32.
This letter develops a framework for EEG analysis and similar applications based on polyharmonic splines. This development overcomes a basic problem with the method of splines in the Euclidean setting: that it does not work on low-degree algebraic surfaces such as spherical and ellipsoidal scalp models. The method's capability is illustrated through simulations on the three-sphere model and using empirical data. 相似文献
33.
Alvaro E. Cuno Parari Claudio Esperança Antonio A. F. Oliveira 《The Visual computer》2009,25(10):911-922
This work presents methods for deforming meshes in a shape-sensitive way using Moving Least Squares (MLS) optimization. It
extends an approach for deforming space (Cuno et al. in Proceedings of the 27th Computer Graphics International Conference,
pp. 115–122, 2007) by showing how custom distance metrics may be used to achieve deformations which preserve the overall mesh shape. Several
variant formulations are discussed and demonstrated, including the use of geodesic distances, distances constrained to paths
contained in the mesh, the use of skeletons, and a reformulation of the MLS scheme which makes it possible to affect the bending
behavior of the deformation. Finally, aspects of the implementation of these techniques in parallel architectures such as
GPUs (graphics processing units) are described and compared with CPU-only implementations. 相似文献
34.
Hub-and-spoke networks are widely studied in the area of location theory. They arise in several contexts, including passenger airlines, postal and parcel delivery, and computer and telecommunication networks. Hub location problems usually involve three simultaneous decisions to be made: the optimal number of hub nodes, their locations and the allocation of the non-hub nodes to the hubs. In the uncapacitated single allocation hub location problem (USAHLP) hub nodes have no capacity constraints and non-hub nodes must be assigned to only one hub. In this paper, we propose three variants of a simple and efficient multi-start tabu search heuristic as well as a two-stage integrated tabu search heuristic to solve this problem. With multi-start heuristics, several different initial solutions are constructed and then improved by tabu search, while in the two-stage integrated heuristic tabu search is applied to improve both the locational and allocational part of the problem. Computational experiments using typical benchmark problems (Civil Aeronautics Board (CAB) and Australian Post (AP) data sets) as well as new and modified instances show that our approaches consistently return the optimal or best-known results in very short CPU times, thus allowing the possibility of efficiently solving larger instances of the USAHLP than those found in the literature. We also report the integer optimal solutions for all 80 CAB data set instances and the 12 AP instances up to 100 nodes, as well as for the corresponding new generated AP instances with reduced fixed costs. 相似文献
35.
Claudio Schepke Nicolas Maillard Philippe O. A. Navaux 《International journal of parallel programming》2009,37(6):593-611
This paper presents and discusses a blocked parallel implementation of bi- and three-dimensional versions of the Lattice Boltzmann
Method. This method is used to represent and simulate fluid flows following a mesoscopic approach. Most traditional parallel
implementations use simple data distribution strategies to parallelize the operations on the regular fluid data set. However,
it is well known that block partitioning is usually better. Such a parallel implementation is discussed and its communication
cost is established. Fluid flows simulations crossing a cavity have also been used as a real-world case study to evaluate
our implementation. The presented results with our blocked implementation achieve a performance up to 31% better than non-blocked
versions, for some data distributions. Thus, this work shows that blocked, parallel implementations can be efficiently used
to reduce the parallel execution time of the method. 相似文献
36.
Arilo Claudio Dias-Neto Guilherme Horta Travassos 《Information and Software Technology》2009,51(11):1487-1504
Selecting software technologies for software projects represents a challenge to software engineers. It is known that software projects differ from each other by presenting different characteristics that can complicate the selection of such technologies. This is not different when considering model-based testing. There are many approaches with different characteristics described in the technical literature that can be used in software projects. However, there is no indication as to how they can fit a software project. Therefore, a strategy to select model-based testing approaches for software projects called Porantim is fully described in this paper. Porantim is based on a body of knowledge describing model-based testing approaches and their characterization attributes (identified by secondary and primary experimental studies), and a process to guide by adequacy and impact criteria regarding the use of this sort of software technology that can be used by software engineers to select model-based testing approaches for software projects. 相似文献
37.
38.
Mario A. S. Lizi��r Marcelo F. Siqueira Joel Daniels II Claudio T. Silva L. Gustavo Nonato 《The Visual computer》2011,27(10):887-903
This paper describes a novel template-based meshing approach for generating good quality quadrilateral meshes from 2D digital
images. This approach builds upon an existing image-based mesh generation technique called Imeshp, which enables us to create a segmented triangle mesh from an image without the need for an image segmentation step. Our
approach generates a quadrilateral mesh using an indirect scheme, which converts the segmented triangle mesh created by the
initial steps of the Imesh technique into a quadrilateral one. The triangle-to-quadrilateral conversion makes use of template meshes of triangles. To
ensure good element quality, the conversion step is followed by a smoothing step, which is based on a new optimization-based
procedure. We show several examples of meshes generated by our approach, and present a thorough experimental evaluation of
the quality of the meshes given as examples. 相似文献
39.
Treatment of prostate cancer patients with antiandrogens is initially successful, though the therapy often becomes refractory over the time. This mechanism is not fully understood, but the presence of androgen receptor (AR) mutant forms which are activated by antiandrogens and other endogenous ligands, and overexpression of the receptor have been suggested. In an attempt to explain the molecular basis for agonicity and antagonicity in the androgen receptor, and the changes on biological activity of subtle modifications at the ligand and receptor (mutations) level, molecular dynamics simulations were performed on the androgen receptor wild type (WT), and T877A and W741 mutant forms, complexed with several non-steroidal androgens. The stabilizing role of residues from helices 3, 5, 11 and 12 was observed in non-steroidal androgens R-3, S-1, and R-bicalutamide and hydroxyflutamide in resistant mutations. In the AR WT antiandrogen R-bicalutamide complex, destabilization of M895 by both W741 and the sulfonyl linkage of the ligand may be responsible for reported antagonism. Changes in the ligand or mutations alleviating this effect were observed to stabilize the receptor in the active conformation, thus developing resistance to R-bicalutamide. The results presented provide a plausible explanation for the molecular basis of agonicity and antagonicity in the androgen receptor, and complement previous studies using static crystal structures, incorporating for the first time protein dynamics into the analysis. Thus, our results provide a valuable framework for the structure-based design of improved antiandrogens. 相似文献
40.
Privacy preserving technologies are likely to become an essential component of adaptive services in pervasive and mobile computing. Although privacy issues have been studied for a long time in computer science as well as in other fields, most studies are focused on the release of data from large repositories. Mobile and pervasive computing pose new challenges, requiring specific formal models for attacks and new privacy preserving techniques. This paper considers a specific pervasive computing scenario, and shows that the application of state-of-the-art techniques for the anonymization of service requests is insufficient to protect the privacy of users. A specific class of attacks, called shadow attacks, is formally defined and a defense technique is proposed. This defense is formally proved to be correct, and its effectiveness is validated by extensive experiments in a simulated environment. 相似文献