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TALN research group at LS2N lab 12

16SC&gs

Interactive synthesis of self-organizing tree models on the GPU

Real-time synthesis of realistic tree models is a desirable functionality for computer games, simulators, and landscape design software. Self-organizing tree models that adapt to the environment are a welcome addition and central to various 3D design tools but present a challenging task for interactive use even on modern commodity hardware. The paper describes the implementation of a complete self-organizing tree synthesis method running on a contemporary graphics processing unit using OpenCL. We demonstrate that generation and display of tree-populated scenes with shadows at interactive rates can be achieved by utilizing the massively parallel GPU architecture to accelerate the computationally intensive steps of the method. A comparison with the performance of single-threaded and CPU-based OpenCL implementation of the same method is reported.

3H51pmX

Palmprint verification with XOR-SUM Code

The proposed work aims to improve the performance of palmprint recognition system by reducing the size of templates. Discrete Wavelet Transform assists in scaling down the size of extracted Region of Interest of palmprint approximately by a factor of 16, while preserving the potential information used to discriminate among different palms. This work proposes XOR-SUM Code, which is based on the fusion of the real and the imaginary Palm Code images for different orientations (say, \(N\)). The fused images of all orientations are added together to get line features of palmprint. The resulting image is then coded into \(\left\lceil (N+1)/2 \right\rceil \) bits to get line features of reduced size. Experiments are carried out on Hong Kong PolyU palmprint database that contains 8000 palmprint images of 400 different palms. XOR-SUM Code technique is compared with Palm Code, Competitive Code, and Contourlet Transform-based techniques in terms of Equal Error Rate (EER), Decidability Index (DI), and Genuine Acceptance Rate (GAR). The XOR-SUM Code technique results in EER, DI, and GAR of 1.83%, 4.4433, and 98.17% respectively.

352-kKA

Comparison of time domain techniques for the evaluation of the response and the stability in long span suspension bridges

During the last decades, several studies on suspension bridges under wind actions have been developed in civil engineering and many techniques have been used to approach this structural problem both in time and frequency domain. In this paper, four types of time domain techniques to evaluate the response and the stability of a long span suspension bridge are implemented: nonaeroelastic, steady, quasi steady, modified quasi steady. These techniques are compared considering both nonturbulent and turbulent flow wind modelling. The results show consistent differences both in the amplitude of the response and in the value of critical wind velocity.

2H9ikTU

a fine-grained model for code mobility

In this paper we take the extreme view that every line of code is potentially mobile, i.e., may be duplicated and/or moved from one program context to another on the same host or across the network. Our motivation is to gain a better understanding of the range of constructs and issues facing the designer of a mobile code system, in a setting that is abstract and unconstrained by compilation and performance considerations traditionally associated with programming language design. Incidental to our study is an evaluation of the expressive power of Mobile UNITY, a notation and proof logic for mobile computing.

-u5-w28

Numerical simulation of turbulent flow in complex geometries used in power plants

Performance degradations or improvements of coal-fired power stations depend on effective functioning of pulveriser equipment and combustion efficiency of furnaces in boilers. The function of a pulveriser is to grind the lumped coal and transfer the fine coal to the furnace for efficient combustion. However, the presence of several solid objects inside the mill, flow of air and particles takes turn around from inlet to outlet. The flow simulation process involves the geometrical modelling, grid generation and particle trajectories for the given flow conditions, and has been investigated to understand the flow path in grinding chamber, separator and classifier. The behaviour of turbulent air flow motion with fly ash particle paths on Lagrangian scale in computational domain are obtained through CFD/CAD software packages. The understanding developed with reference to recirculation flows in the inlet duct, non-uniform flow over the height of bowl mill and unequal flow at exit, provides valuable insights to designers for optimisation of components for better efficiency.

32o:ifJ

On the enrouting protocol problem under uncertainty ?

In this paper we present a two-stage stochastic mixed 01 dynamic multicommodity model and algorithm for determining the enrouting protocol in the telecommunications network under uncertainty. Given the network connectivity, node processing and buffer and arc flow capacity, the aim is to determine the outgoing arc for the information flow reaching a given node for each destination terminal node (i.e., obtaining the route to be followed by the information flow from each origin terminal node to each destination terminal node). The origindestination (OD) flow matrix is given by the number of information packets to be sent from the origin terminal nodes to the destination terminal nodes along a given time horizon, i.e., a call scale. The uncertainty in the OD flow matrix is treated via a scenario tree approach. The main goal is to minimize a composite function of the expected lost information, a penalization of the deviation from the FIFO strategy on the information flow entering the network, and the expected number of nodes visited by the information packets. A mixture of an enrouting arc generation scheme and a genetic algorithm for obtaining the enrouting protocols over the scenarios is presented. The tool presented in this paper could be used for simulating the enrouting protocols to analyze the saturation of the network, but it has a time constraint for real time operation. Faster algorithms are needed to define the routing tables during the operation stage. Computational experience is reported.

3eA-EX5

Convergence of the multigrid method for ill-conditioned block Toeplitz systems

We study the solutions of block Toeplitz systems A(mn)u = b by the multigrid method (MGM). Here the block Toeplitz matrices A(mn) are generated by a nonnegative function f(x; y) with zeros. Since the matrices A(mn) are ill-conditioned, the convergence factor of classical iterative methods will approach 1 as the size of the matrices becomes large. These classical methods, therefore, are not applicable for solving ill-conditioned systems. The MGM is then proposed in this paper. For a class of block Toeplitz matrices, we show that the convergence factor of the two-grid method (TGM) is uniformly bounded below 1 independent of mn and the full MGM has convergence factor depending only on the number of levels. The cost per iteration for the MGM is of O(mn log mn) operations. Numerical results are given to explain the convergence rate.

4-oxc:H

Grid Service Reliability Modeling and Optimal Task Scheduling Considering Fault Recovery

There has been quite some research on the development of tools and techniques for grid systems, yet some important issues, e. g., grid service reliability and task scheduling in the grid, have not been sufficiently studied. For some grid services which have large subtasks requiring time-consuming computation, the reliability of grid service could be rather low. To resolve this problem, this paper introduces Local Node Fault Recovery (LNFR) mechanism into grid systems, and presents an in-depth study on grid service reliability modeling and analysis with this kind of fault recovery. To make LNFR mechanism practical, some constraints, i.e. the life times of subtasks, and the numbers of recoveries performed in grid nodes, are introduced; and grid service reliability models under these practical constraints are developed. Based on the proposed grid service reliability model, a multi-objective task scheduling optimization model is presented, and an ant colony optimization (ACO) algorithm is developed to solve it effectively. A numerical example is given to illustrate the influence of fault recovery on grid service reliability, and show a high efficiency of ACO in solving the grid task scheduling problem.

1za2px7

A theoretical aspect of a stochastic sketching method for global optimization

In this paper, we propose Stochastic Sketching method for global optimization based on the simulation of human behavior. Stochastic Sketching models the thought process and strategies of human beings and applying the artificial model to problems. We introduce and discuss concepts and components essential to Stochastic Sketching in detail, including the sampling guide, zooming controller, sketching model, precision threshold, and satisfaction probability. The mathematical foundations of Stochastic Sketching are discussed and a preliminary theoretical base is presented.