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161.
Rui C. Gonçalves Don Batory João L. Sobral Taylor L. Riché 《Software and Systems Modeling》2017,16(4):929-947
Dataflow programs are widely used. Each program is a directed graph where nodes are computations and edges indicate the flow of data. In prior work, we reverse-engineered legacy dataflow programs by deriving their optimized implementations from a simple specification graph using graph transformations called refinements and optimizations. In MDE speak, our derivations were PIM-to-PSM mappings. In this paper, we show how extensions complement refinements, optimizations, and PIM-to-PSM derivations to make the process of reverse engineering complex legacy dataflow programs tractable. We explain how optional functionality in transformations can be encoded, thereby enabling us to encode product lines of transformations as well as product lines of dataflow programs. We describe the implementation of extensions in the \(\mathtt{ReFlO}\) tool and present two non-trivial case studies as evidence of our work’s generality. 相似文献
162.
163.
Demanding the compatibility of semi-Lagrangian trajectory schemes with the fundamental Euler expansion formula leads to the Monge-Ampère (MA) nonlinear second-order partial differential equation. Given standard estimates of the departure points of flow trajectories, solving the associated MA problem provides a corrected solution satisfying a discrete Lagrangian form of the mass continuity equation to round-off error. The impact of the MA enhancement is discussed in two diverse limits of fluid dynamics applications: passive tracer advection in a steady cellular flow and in fully developed turbulence. Improvements of the overall accuracy of simulations depend on the problem and can be substantial. 相似文献
164.
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
165.
Since wavelets were introduced in the radiosity algorithm 5 , surprisingly little research has been devoted to higher order wavelets and their use in radiosity algorithms. A previous study 13 has shown that wavelet radiosity, and especially higher order wavelet radiosity was not bringing significant improvements over hierarchical radiosity and was having a very important extra memory cost, thus prohibiting any effective computation. In this paper, we present a new implementation of wavelets in the radiosity algorithm, that is substantially different from previous implementations in several key areas (refinement oracle, link storage, resolution algorithm). We show that, with this implementation, higher order wavelets are actually bringing an improvement over standard hierarchical radiosity and lower order wavelets. 相似文献
166.
Jean-François Monin 《Formal Methods in System Design》2000,17(3):221-243
Conformance control for ATM cells is based on a real-time reactive algorithm which delivers a value depending on inputs from the network. This value must always fit with a well defined theoretical value. We present here the correctness proof of the algorithm standardized for the ATM transfer capability called ABR. The proof turned out to produce a key argument during the standardization process of ABR. 相似文献
167.
2 1/2 D Visual Servoing with Respect to Unknown Objects Through a New Estimation Scheme of Camera Displacement 总被引:9,自引:0,他引:9
Classical visual servoing techniques need a strong a priori knowledge of the shape and the dimensions of the observed objects. In this paper, we present how the 2 1/2 D visual servoing scheme we have recently developed, can be used with unknown objects characterized by a set of points. Our scheme is based on the estimation of the camera displacement from two views, given by the current and desired images. Since vision-based robotics tasks generally necessitate to be performed at video rate, we focus only on linear algorithms. Classical linear methods are based on the computation of the essential matrix. In this paper, we propose a different method, based on the estimation of the homography matrix related to a virtual plane attached to the object. We show that our method provides a more stable estimation when the epipolar geometry degenerates. This is particularly important in visual servoing to obtain a stable control law, especially near the convergence of the system. Finally, experimental results confirm the improvement in the stability, robustness, and behaviour of our scheme with respect to classical methods. 相似文献
168.
António V. Sousa Ana Maria Mendonça Aurélio Campilho 《Pattern Analysis & Applications》2008,11(3-4):409-423
This paper proposes a non-parametric method for the classification of thin-layer chromatographic (TLC) images from patterns represented in a dissimilarity space. Each pattern corresponds to a mixture of Gaussian approximation of the intensity profile. The methodology comprises various phases, including image processing and analysis steps to extract the chromatographic profiles and a classification phase to discriminate among two groups, one corresponding to normal cases and the other to three pathological classes. We present an extensive study of several dissimilarity-based approaches analysing the influence of the dissimilarity measure and the prototype selection method on the classification performance. The main conclusions of this paper are that, Match and Profile-difference dissimilarity measures present better results, and a new prototype selection methodology achieves a performance similar or even better than conventional methods. Furthermore, we also concluded that simplest classifiers, such as k-NN and linear discriminant classifiers (LDCs), present good performance being the overall classification error less than 10% for the four-class problem. 相似文献
169.
David-A. Mendels Emmelyn M. Graham Steven W. Magennis Anita C. Jones François Mendels 《Microfluidics and nanofluidics》2008,5(5):603-617
The development and adoption of lab-on-a-chip and micro-TAS (total analysis system) techniques requires not only the solving
of design and manufacturing issues, but also the introduction of reliable and quantitative methods of analysis. In this work,
two complementary tools are applied to the study of thermal and solutal transport in liquids. The experimental determination
of the concentration of water in a water–methanol mixture and of the temperature of water in a microfluidic T-mixer are achieved
by means of fluorescence lifetime imaging microscopy (FLIM). The results are compared to those of finite volume simulations
based on tabulated properties and well-established correlations for the fluid properties. The good correlation between experimental
and modelled results demonstrate without ambiguity that (1) the T-mixer is an adiabatic system within the conditions, fluids
and flow rates used in this study, (2) buoyancy effects influence the mixing of liquids of different densities at moderate
flow rates (Reynolds number Re ≪ 10−2), and (3) the combination of FLIM and computational fluid dynamics has the potential to be used to measure the thermal and
solutal diffusion coefficients of fluids for a range of temperatures and concentrations in one single experiment. As such,
it represents a first step towards the full-field monitoring of both the extent and the kinetics of a chemical reaction.
相似文献
David-A. MendelsEmail: |
170.
Improving security and performance of an Ad Hoc network through a multipath routing strategy 总被引:1,自引:0,他引:1
Hervé Aiache François Haettel Laure Lebrun Cédric Tavernier 《Journal in Computer Virology》2008,4(4):267-278
Privacy and security solutions require today the protection of personal information so that it may not be disclosed to unauthorized
participant for illegal purposes. It is a challenge to address these issues in networks with strong constraints such as Ad
Hoc network. The security increase is often obtained with a quality of service (QoS) decrease. We propose in this paper a
solution that provides at the anonymity, security to Ad Hoc network with a limited impact on QoS. This method could be efficient
against some viral attacks. We also give some security proofs of our solution for Ad Hoc networks.
The work of Hervé Aiache and Cédric Tavernier was supported by DISCREET, IST project no. 027679, funded in part by the European
Commission’s Information Society Technology 6th Framework Programme. 相似文献