Showing papers by "Grenoble Institute of Technology published in 2000"

Fault injection in VHDL descriptions and emulation

Abstract: Analyzing at an early stage of the design the potential faulty behaviors of a circuit becomes a major concern due to the increasing probability of faults. It is proposed to carry out such an analysis using fault injections in RT-level VHDL descriptions and hardware prototyping of the circuit under design. Injection of erroneous transitions is automated and results are presented.

Electrochemical properties of Ni-YSZ cermet in solid oxide fuel cells

Abstract: The effects of various current collectors on the electrochemical property measurements of a Ni-YSZ cermet have been investigated. Electrochemical characteristics were determined by impedance spectroscopy (IS) at open-circuit voltage in H -H O atmosphere at 8008C using a symmetrical cell. We selected various current collectors made of gold, platinum and 22 nickel and with two different structures, paste and mesh. When using paste, the electrochemical response, recorded with the same Ni-YSZ cermet sample, depends greatly on the nature of the current collector. Polarization resistance values follow the order: Ni , Pt , Au. This is the same order as reported in the literature for the hydrogen electrochemical oxidation activities of these metals. This demonstrates that paste current collectors interfere with the electrochemical properties of the anode material. Therefore, in order to compare the electrochemical activities of various anode materials, the same current collector has to be used. We have also observed that the polarization resistance increases with time, due to metal particle diffusion through the Ni-YSZ cermet. When using a nickel mesh, the electrochemical properties do not vary with time. Moreover, the structure of this current collector is most similar to the interconnect materials, which are the current collectors in planar SOFCs. It is, therefore, the best current collector for the study of the electrochemical properties of Ni-YSZ cermet. © 2000 Elsevier Science B.V. All rights reserved.

More on the Mis-Specification of the Shape Parameter with Weibull-to-Exponential Transformation

Abstract: When lifetimes follow Weibull distribution with known shape parameter, a simple power transformation could be used to transform the data to the case of exponential distribution, which is much easier to analyze. Usually, the shape parameter cannot be known exactly and it is important to investigate the effect of mis-specification of this parameter. In a recent article, it was suggested that the Weibull-to-exponential transformation approach should not be used as the confidence interval for the scale parameter has very poor statistical property. However, it would be of interest to study the use of Weibull-to-exponential transformation when the mean time to failure or reliability is to be estimated, which is a more common question. In this paper, the effect of mis-specification of Weibull shape parameters on these quantities is investigated. For reliability-related quantities such as mean time to failure, percentile lifetime and mission reliability, the Weibull-to-exponential transformation approach is generally acceptable. For the cases when the data are highly censored or when small tail probability is concerned, further studies are needed, but these are known to be difficult statistical problems for which there are no standard solutions. Copyright © 2000 John Wiley & Sons, Ltd.

A LMI approach to robust observer design for linear time-delay systems

Abstract: This paper is concerned with a robust observer design for linear time-delay systems via linear matrix inequality approach. The proposed method not only guarantees the stability of the proposed observer, but also reduces the effects of different unstructured uncertainties on the estimated error.

A French Phonetic Lexicon with Variants for Speech and Language Processing

Abstract: This paper reports on a project aiming at the semi-automatic development of a large orthographic-phonetic lexicon for French, based on the Multext dictionary. It details the various stages of the project, with an emphasis on the methodological and design aspects. Information regarding the lexicon’s content is also given, together with a description of interface tools which should facilitate its exploitation.

Labeling audio-visual speech corpora and training an ANN/HMM audio-visual speech recognition system.

Abstract: We present a method to label an audio-visual database and to setup a system for audio-visual speech recognition based on a hybrid Artificial Neural Network/Hidden Markov Model (ANN/HMM) approach. The multi-stage labeling process is presented on a new audiovisual database recorded at the Institute de la Communication Parlee (ICP). The database was generated via transposition of the audio database NUMBERS95. For the labeling first a large subset of NUMBERS95 is used to achieve a bootstrap training of an ANN, which can then be employed to label the audio part of the audio-visual database. This initial labeling is further improved via readapting the ANN to the new database and reperforming the labeling. From the audio labeling then the video labeling is derived. Tests at different Signal to Noise Ratios (SNR) are performed to demonstrate the efficiency of the labeling process. Furthermore ways to incorporate information from a large audio database into the final audio-visual recognition system were investigated.

Optimized Generation of VHDL Mutants for Injection of Transition Errors

Abstract: Fault injection in VHDL descriptions has become an efficient solution to analyze at an early stage of the design the potential faulty behaviors of a complex digital circuit Such injections may use either saboteurs or mutants In this paper, the focus is placed on "controlled generation" of mutants, which means that the generation of mutants is (1) done for precise fault/error models related to faults occurring in the field and (2) optimized for synthesis onto emulation hardware Several approaches are proposed to inject transition errors in FSMs or RT-level control flowcharts These approaches are compared and the results show the impact of the mutant generation on the result efficiency

Une base de données cinéradiographiques du français.

Abstract: This paper presents a preliminary version of a large X-ray database that is currently being elaborated at both the Institut de Phonetique de Strasbourg and the Institut de la Communication Parlee de Grenoble. It currently contains 4 movies that present over 2000 images. These X-ray data focus on different phonetic issues in French: juncture, nasals, and coarticulation in VCV sequences. The database contains 3 kinds of digitized data; the cineradiographic data, acoustic signals and hand-drawn sagittal contours of the vocal tract. All files are phonetically labeled and stored on CD ROMs. Management of the database is developed for Windows NT or Windows 95 with "Microsoft ACCESS", with a version for Macintosh. The data are accessed via requests in SQL language, and a user friendly interface is developed under JAVA, allowing easy formulation of requests, display of selected X-ray images and of vocal tract contours, and also listening the selected video portions.

Hierarchical interfaces for hardware software systems

Abstract: Competent design of hierarchical interfaces for hardware/software systems needs the convergence of three concurrent research directions: the study of hierarchy types, the intelligent communication between different domains, the formalization of verification/test. We aim to extend the theory of hierarchy types, in order to integrate communication properties as well as correctness and testability, to suit the behavioral specification of today’s complex system design. The high level approach of these problems permits the intervention of an intelligent agent for adapting techniques, models or methods to the particular design: a designer, assisted by man-machine dialog interface, or an artificial intelligence system. Behavioral design-for-testability offers a good startup. Testability measures the difficulty of test; it is used in this paper to emphasize the high-level strategy. Design-for-testability techniques (full and partial scan, test point insertion or builtin self-test) increase the fault coverage and reduce the test generation time; as they aim to modify the system's specification to improve testability, performing them at higher levels of the design hierarchy reduces the complexity of their generation and application. An intelligent use of the acquired knowledge on design for communication, verification and testability is enabled.

Anisotropy of paper: comparison of different laser tools

Abstract: Papermaking process consists in a succession of unit operations for having main objective the expression of water out of the wet paper pad. The three main stages are successively, the forming section, the press section and finally the drying section. Pressing is not on the scope of this paper but the influence of formation and drying on anisotrophy of paper properties is analyzed. More specifically, optical measurements are described in order the anisotropic structure and physical properties of paper to be analyzed.

A front-end using the harmonicity cue for speech enhancement in loud noise

Abstract: Keywords: speech Note: no IDIAPRR, see RESPITE www Reference EPFL-CONF-82650 Record created on 2006-03-10, modified on 2017-05-10

Multi-sensor reception for TDD-UMTS mobile terminal in indoor and pedestrian environments

Abstract: In the downlink TD/CDMA multiple access scheme through a multipath channel, the use of a short complex code enables a strategy of multi-user detection with great sensibility improvement compared to the traditional matched filter. Nevertheless, the performances are damaged compared to the situation with an ideal channel, more especially as the number of users increases. In this paper, we first use the cross-spectral matrix of the aliased coded channels to recall linear multi-user detector (ZF and MMSE) and express a degradation factor of interference and noise to signal ratio due to a non-ideal channel, with or without fading. The degradation and bit error probability are then computed in the concrete situation of indoor and pedestrian channel environments in order to show the great benefit of one or two supplementary sensors at the reception system.

Modelling Quasicrystal Plastic Deformation By Means of Constitutive Equations

Abstract: The interpretation of plastic deformation experiments on quasicrystals is a challenging task due to the occurrence of changes of the structure during deformation. In this paper, we present a quantitative model for quasicrystal plasticity on the basis of a constitutive-equations Ansatz, which takes these effects into account. A single-internal-variable model of the kind commonly used for describing crystal plasticity, is adapted for the description of the dislocation density evolution in a quasicrystal. In addition, we introduce a structural parameter that accounts for the evolution of order in the course of plastic deformation. The numerical solution of the resulting set of evolution equations yields the flow stress and the dislocation density as a function of strain, which can be directly compared to corresponding experimental curves obtained on icosahedral Al-Pd-Mn. An excellent agreement between experiment and the calculated curves obtained using our model is found.

Germania sol-gel waveguides for optical amplifiers

Abstract: Sol-gel is one of the possible production techniques of silica-on-silicon integrated optical devices, combining low cost with a great flexibility. In the frame of a European project, we have investigated the application of the sol-gel technique for the realization of an erbium-doped optical amplifier. In particular we developed GeO2-SiO2-Al2O3 sol-gel waveguides doped with Er. The material was optimized in terms of heat treatments, Al2O3 co- doping content and Er doping level. RBS measurements showed that well densified films could be obtained heating the coatings at 700 degrees C in O2 flux. Waveguide properties were tested measuring the propagation losses at 840 nm. In the planar waveguide pumped at 980 nm, erbium showed fluorescence around 1530 nm with up to 6.5 ms. In order to achieve lateral confinement, the planar waveguides were co-doped with Na2O and channel waveguides were fabricated by ion exchange. The feasibility of sodium-silver and sodium-potassium ion exchange was demonstrated. The influence of the process parameters on passive and active optical properties of the films was studied and straight channel waveguides with Gaussian mode profiles were obtained by the sodium-silver route.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Parallel and Distributed Computing: State-of-the-Art and Emerging Trends

Abstract: This chapter presents an introduction to the area of Parallel and Distributed Computing. The aim is to recall the main historical steps in order to present the future trends and emerging topics. Four major research areas are detailed within this perspective and discussed. They concern respectively the needs of parallel resources for solving large actual applications, the evolution of parallel and distributed systems, the programming environment and some theoretical foundations for the design of efficient parallel algorithms.

Characterization of the 118-GHz ECRH output beam on Tore Supra

Abstract: The characterization of the electromagnetic field at the electron cyclotron frequency is one important point for the ECRH installation under development at the CEA Cadarache. This characterization is based on a mathematical decomposition of the electromagnetic field over the various radiating modes of an oversized corrugated waveguide. To perform this determination, which principle is given in the paper, one has to access the amplitude and the phase of the full electric field on a plane transverse to the propagation direction. It is possible to obtain amplitude and phase diagrams of the two crossed polarization at low level. At high level, in the output of a gyrotron, one uses only thermal measurements and the phase is reconstructed from the amplitude diagrams. The paper exposes a compete validation of this method and gives and results of the high level characterization.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Modeling and simulation of guided-wave photonic band gap devices

Abstract: The Guided wave Photonic Band Gap (PBG) structures are very attractive as optical devices. The modeling and the simulation of such structures is topic of great interest because the classical existing optical modeling techniques, such as BPM or effective index, are not compatible with the size and propagation effects in PBG structures. In this communication we focus on guided PBG filters. Two simulations are presented. The first one is a circuit approach. It is based on the modeling of the PBG as a cascade of several obstacles connected to waveguides. For each obstacle the S-parameters are calculated. Finally these parameters are implemented in a microwave simulator which determines the response of the PBG Filter. The second approach uses a numerical technique. We have simulated diffraction effects using 2D-FDTD and 3D-TLM methods. The simulation allows us to investigate the PBG mirror diffraction losses for different design parameters.

Perception and Analysis of a Reiterant Speech Paradigm: a Functional Diagnostic of Synthetic Prosody

Abstract: A set of perception experiments, using reiterant speech, were designed to carry out a diagnostic of the segmentation / hierarchisation linguistic function of prosody. The prosodic parameters of F0, syllabic duration and intensity of the stimuli used during this experiment were extracted. Several dissimilarity measures (Correlation, root-mean-square distance and mutual information) were used to match the results of the subjective experiment. This comparison of the listeners’ perception with acoustic parameters is intended to underline the acoustic keys used by listeners to judge the adequacy of prosody to perform a given linguistic function.

Simple effective tests for beam propagation method programs

Abstract: In view of the increased need of an effective, practical and unified test set to evaluate the modeling capabilities (and ultimately the trustworthiness) of beam propagation method (BPM) based programs, we propose a incipient set of tests to be used for a standard evaluation. The proposed tests have been chosen to be simple, easy to implement and enable a fairly good (although not complete) evaluation without the need of any experiment, Interesting aspects of the tests' results and some straightforward, practical criteria to estimate program capabilities and to tune the simulation parameters are presented. A cross-checking between `Mode Solver' (MS) based and BPM based programs is also put into discussion. A paraxial error evaluation method is presented and the transverse mesh influence on the paraxial error is analyzed.

Aerosol)gel preparation of optically active layers in the system

Abstract: Er-doped silica)titania multilayer coatings have been successfully deposited using an original sol)gel deposition technique: the Aerosol)gel process. This study is the first step toward Aerosol)gel preparation of active planar wave guides. In this paper, we report on the physical, chemical, optical, microstructural and spectroscopic properties of the multilayer coatings. A new optically . active crystalline phase, Er Ti O ETO , has been identified. This study shows that, depending on the experimental conditions 227 .titanium and erbium content, heat treatment temperature , ETO can be obtained in the form of nanocrystallites dispersed in a transparent amorphous matrix. Q 2000 Elsevier Science S.A. All rights reserved.