http://hdl.handle.net/2268/86 Search this channel search http://orbi.ulg.ac.be/simple-search http://hdl.handle.net/2268/147623 Title: Evaluation of the acoustic comfort of air-treatment systems with a multi-task procedure <br/> <br/>Author, co-author: Minard, Antoine; Robin, Benjamin; Fournier, Francette; Embrechts, Jean-Jacques; Billon, Alexis; Goujard, Bertrand; Sakout, Anas http://hdl.handle.net/2268/147407 Title: Modeling of Electromagnetic Systems by Coupling of Subproblems – Application to Thin Shell Finite Element Magnetic Models <br/> <br/>Author, co-author: Dang, Quoc Vuong <br/> <br/>Abstract: The direct application of the finite element method to realistic electromagnetic problems is challenging, especially when modeling structures with thin conductive and/or magnetic parts. This work presents a subproblem method for correcting the inaccuracies inherent to classical thin shell models, and to efficiently handle geometrical and material variations in parametric studies. http://hdl.handle.net/2268/147353 Title: Nonlinear guitar loudspeaker simulation <br/> <br/>Author, co-author: Schmitz, Thomas; Embrechts, Jean-Jacques http://hdl.handle.net/2268/147156 Title: Dual Formulations for Accurate Thin Shell Models in a Finite Element Subproblem Method <br/> <br/>Author, co-author: Dang, Quoc Vuong; Dular, Patrick; Vazquez Sabariego, Ruth; Laurent, Krähenbühl; Geuzaine, Christophe <br/> <br/>Abstract: A subproblem finite with dual finite element magnetostatic and magnetodynamic formulations is developed for correcting the inaccuracies near edges and corners coming from thin shell models, that replace thin volume regions by surfaces. The surface-to-volume correction problem is defined as one of the multiple subproblems applied to a complete problem, considering successive additions of inductors and magnetic or conducting regions, some of these being thin regions. Each SP requires a proper adapted mesh of its regions, which facilitates meshing and increases computational e ciency. http://hdl.handle.net/2268/147114 Title: A Diffraction Model for Acoustical Ray-Tracing Based on the Energy Flow Lines Concept <br/> <br/>Author, co-author: Billon, Alexis; Embrechts, Jean-Jacques <br/> <br/>Abstract: Geometrical acoustics models are currently the most popular prediction tools in room-acoustics due to their low computing load. However, they seldom take into account the diffraction occurring at free edges. Moreover, the existing diffraction models implemented in geometrical acoustics algorithms are either limited to specularly reflected paths or either present excessive computation load. Recently, a diffraction model based on an approximation of the far-field direction of the Poynting’s vector around half-planes has been introduced for computing the scattering due to faceted dielectric objects. In this article, this model is developed to handle obliquely incident waves and is implemented within an acoustic ray-tracing software using the analogy between the Poynting’s and the acoustic intensity vectors. The proposed model can handle both diffuse and specular reflections and sets no limit in terms of reflection or diffraction order. The first results obtained by ray-tracing agree well with the uniform theory of diffraction and the boundary elements method for single and double diffraction problems even if the interference effects are neglected and as long as the number of emitted rays is sufficient. Moreover, the additional computation load to handle diffraction is shown to be low compared to the one from a classical ray-tracing algorithm. http://hdl.handle.net/2268/146692 Title: Contingency ranking with respect to overloads in very large power systems taking into account uncertainty, preventive, and corrective actions <br/> <br/>Author, co-author: Fliscounakis, Stéphane; Panciatici, Patrick; Capitanescu, Florin; Wehenkel, Louis <br/> <br/>Abstract: This paper deals with day-ahead security management with respect to a postulated set of contingencies, while taking into account uncertainties about the next day generation/load scenario. In order to help the system operator in decision making under uncertainty, we aim at ranking these contingencies into four clusters according to the type of control actions needed to cover the worst uncertainty pattern of each contingency with respect to branch overload. To this end we use a fixed point algorithm that loops over two main modules: a discrete bi-level program (BLV) that computes the worst-case scenario, and a special kind of security constrained optimal power flow (SCOPF) which computes optimal preventive/corrective actions to cover the worst-case. We rely on a DC grid model, as the large number of binary variables, the large size of the problem, and the stringent computational requirements preclude the use of existing mixed integer nonlinear programming (MINLP) solvers. Consequently we solve the SCOPF using a mixed integer linear programming (MILP) solver while the BLV is decomposed into a series of MILPs. We provide numerical results with our approach on a very large European system model with 9241 buses and 5126 contingencies. http://hdl.handle.net/2268/146470 Title: Study of interface trap density in a GeSn MOS structure by numerical simulation of the electrical characteristics <br/> <br/>Author, co-author: Baert, Bruno; Gupta, Somya; Schmeits, Marcel; Simoen, Eddy; Nguyen, Ngoc Duy http://hdl.handle.net/2268/145851 Title: Development of an automatic reference system for directly quantifying drowsiness from a few polysomnographic signals <br/> <br/>Author, co-author: François, Clémentine; Kirkove, Murielle; Wertz, Jérôme; Langohr, Thomas; POIRRIER, Robert; Verly, Jacques http://hdl.handle.net/2268/145813 Title: Perception et confort acoustiques des Systèmes de Traitement d'Air <br/> <br/>Author, co-author: Minard, Antoine <br/> <br/>Abstract: This thesis addresses the perceived acoustic comfort of Air-Treatment Systems (ATS), such as air-conditioners installed in offices, by taking into account the environmental factors related to the specific context of ATS usage. The only existing standard to evaluate the sounds emitted by ATS, which is the emitted sound level in dBA, is only loosely related to perception. Therefore, the need of manufacturers for a more reliable standard arises. This implies a thorough study of the perception of the sound of ATS as it is emitted. A precise methodology was then followed: it includes first collecting a high number of ATS sound recordings, up to finally developing a robust metrics to predict the perceived sound quality. For that purpose, different perceptual categories were first identified to constitute the recording database of ATS sounds. A corpus considered as fully representative of the different types of emitted sounds was then extracted from the recording database. Current principles of musical timbre description have already proved to be adequate to other types of environmental sounds; by applying these principles, the relevant auditive attributes for the corpus perceptual description were identified. In order to develop an efficient sound quality predictor through audio features calculation, prominent features based on these auditive attributes were identified that explain the listeners' preferences among ATS sounds. The ecological context of ATS was examined in a second step. Two environmental factors were addressed in the context of ATS sound quality evaluation to ponder their importance in the listeners' perception. As the ATS under study are exclusively indoor systems designed for offices, the effect of reverberation on sound quality evaluation was first studied; for that purpose, an auralization tool was used to simulate room acoustic response. The influence of listeners' attention context on perceived sound quality was then evaluated through a comparative study of various listening conditions. As a matter of fact, the sound emitted by ATS in real conditions is perceived as a perturbation of current activities. It is therefore relevant to evaluate how deeply the degree of attention related to the sound affects listeners as regards their perception of acoustic quality. Eventually, the relevance of the proposed sound quality predictor to comfort perception was assessed in conditions more ecologically representative than usual laboratory environment. http://hdl.handle.net/2268/145803 Title: Impacts of a unicellular mechanism on network behaviors <br/> <br/>Author, co-author: Dethier, Julie; Drion, Guillaume; Franci, Alessio; Sepulchre, Rodolphe <br/> <br/>Abstract: Parkinson’s disease (PD) is a neurodegenerative disorder af- fecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of the striatum—the input stage of the BG—altering information patterns along movement- related ganglia-mediated pathways in the brain. Severe mo- tor symptoms result from the pathological state: tremor at rest, bradykinesia—the slowness and impaired scaling of voluntary movement—and akinesia—the poverty of volun- tary movements. It is still unclear how dopamine depletion causes those motor symptoms. Experimental studies have shown that abnormally synchronized oscillatory activities— rhythmic bursting activity at the unicellular level and beta frequency band (from 8 to 30Hz) oscillations at the network level—emerge in PD at multiple levels of the BG-cortical loops and correlate with motor symptoms. The mechanisms underlying these pathological beta oscillations remain elu- sive. We propose that a cellular mechanism generates burst- ing activities and beta band oscillations at the network level. http://hdl.handle.net/2268/145340 Title: Experimental Analysis of Spectra of Metallic Elements in Solid Samples by Laser-Induced Breakdown Spectroscopy <br/> <br/>Author, co-author: Li, Jie; Lu, Jidong; Lin, Zhaoxiang; Xie, Chengli; Liu, Linmei; Yao, Shunchun; Li, Pengyan <br/> <br/>Abstract: The life of laser-induced plasma is usually in theLs region, and it is necessary to study the temporal evolution of the plasma in order to optimize the signal detection. Calibration curve is the basis of quantitative analysis, which closely relates to the sensitivity and accuracy. The plasmas were induced by a focused, pulsed laser. The emission spectra of plasmas were then dispersed by an Echelle spectrograph and detected by an intensified charge-coupled device (ICCD). Graphite was the major constituent of the sample, and Ca, Al, Na, K elements were added to pellet the sample respectively. The spectra including the emission lines of Ca, Al, Na, K elements were presented. The temporal evolution curves of the plasmas were obtained via the experimental system of using the gating periods of 100 ns of ICCD. The calibration curves of the lines intensities were obtained. The calibration curves were also analyzed, whose slope are different for the spectra line of the same element of the sample at different wavelength. http://hdl.handle.net/2268/145328 Title: Quantitative analysis of atmosphere by laser—induced breakdown spectroscopy <br/> <br/>Author, co-author: Yu, Liangying; Lu, Jidong; Chen, Wen; Huang, Lai; Li, Jie; Xie, Chengli <br/> <br/>Abstract: In order to investigate the feasibility of quantitative analysis with laser—induced breakdown spectroscopy， plasmas were produced by a Q—switched Nd ：YAG laser interacted with the air at atmospheric pressure，then the light of plasmas entered the monochrom eter and transferred into an electric signal，and the spectra of these plasmas in the range of 600～ 800 nm were stored and analyzed by the calibration—free mode1．Under the condition of delay time of 8 s and gating pulse of 0．4 s，the temperature of plasmas，which was in local thermal equilibrium (LTE)，was 1．62× 10 K which was obtained by means of the two—dimensional Boltzmann plane．The 20．75 oxygen content and 79．25％nitrogen content in air were detected on the assum ption that there were only oxygen and nitrogen constituents in the air．The results coincide well with the fact．The feasibility was validated by the experiment，and it built a strong basis for the further study and experiment of air pollutant monitoring． http://hdl.handle.net/2268/145323 Title: Investigation on Laser-induced Breakdown Spectroscopy of Potassium Chloride Solution <br/> <br/>Author, co-author: Zhang, Wenyan; Lin, Zhaoxiang; Lu, Jidong; Li, Jie; Wu, Jinquan; Sun, Fenglou <br/> <br/>Abstract: The experimental setup for laser—induced breakdown spectroscopy test was designed with pulsed Nd：YAG laser，spectrograph and ICCD and so on．Furthermore the potassium chloride solution spectra signals were detected by this setup．The spectra lines of the trace elements such as natrium (20mg／1)，magnesium(1 mg／1)，calcium(3 mg／1)are recorded．Experiment results show that delay time is one of the important parameters when qualitative analysis．It is easy for LIBS technology to detect multi—elements simultaneity if delay time is appropriate，and qualitative analysis has demonstrated that the feasibility of detecting trace poisonous metals in waste water using LIBS、 http://hdl.handle.net/2268/145319 Title: Experimental investigation on plasma temperature of Ca by laser—induced breakdown spectroscopy <br/> <br/>Author, co-author: Li, Jie; Lu, Jidong; Lin, Zhaoxiang; Xie, Chengli; Chang, Liang; Yang, Lifei <br/> <br/>Abstract: The )lasma temperature is an important factor in quantitative analysis by laser induced breakdown spectroscopy(LIBS)．The plasmas were generated by a Nd：YAG laser 0n the surface of sample and detected by an Echelle spectrograph and an Intensified Charge—Couplea Device(ICCD)．The spectrum of 300 nm to 450 nm recorded several spectral lines of Ca component such as Ca II 31 5．9 nm．Ca II 317．9 nrn．Ca 1I 393．4 nm，Ca Ⅱ 396．9 nm，Ca I 422．7 nm and so on．It is known that the change of plasma temperature has influence on the line intensity from the equation for quantitative LIBS analysis．It was assumed that the plasm as produced in the experiment were in local thermodynamic equilibrium(LTE)．The temperature variations were deduced bv tine four 0ne—ionized Ca spectral lines and the Boltzmann plot，and the relationship between the plasma temperature and the concentration was obtained too．The plasma temperature increased when the concentration increased．When the mass fraction of Ca was lower than 0.50, the increase velocity of the plasma temperature was small. When the mass fraction of Ca was higher than 0.50, the increase was large．The hypothesis of local thermal equilibrium conditions of the plasma was confirmed in this experiment. http://hdl.handle.net/2268/145207 Title: Spatialisation sonore précise pour le cinéma 3D <br/> <br/>Author, co-author: André, Cédric http://hdl.handle.net/2268/145108 Title: Control of Dispersed Generation to Regulate Distribution and Support Transmission Voltages <br/> <br/>Author, co-author: Valverde, Gustavo; Van Cutsem, Thierry <br/> <br/>Abstract: This paper presents an on-line centralized controller based on Model Predictive Control concepts to regulate distribution network voltages, and possibly support transmission network. It computes and applies a sequence of changes of the distributed generators power outputs to progressively meet a set of operation constraints at distribution, and possibly transmission level. An 11-kV, 75-bus test system with 22 distributed generators is used to illustrate the performance of the proposed controller when transmission system support is requested. Comparisons with single-step open-loop control are also provided. http://hdl.handle.net/2268/145103 Title: Distributed load interruption and shedding against voltage delayed recovery or instability <br/> <br/>Author, co-author: Otomega, Bogdan; Van Cutsem, Thierry <br/> <br/>Abstract: This paper deals with a two-part system integrity protection scheme to be installed in distribution networks, to counteract fault-induced delayed voltage recovery or even short-term voltage instability due to induction motors. The first part consists of a fast triggered but temporary reduction of some loads to facilitate motor re-acceleration after fault clearing. The second part resorts to load shedding, as a back-up. The scheme relies on purely distributed controllers; each of them measures a bus voltage and interrupts/disconnects load at the same bus. Tests have been performed on a generic MV/LV system. They illustrate the benefit of load interruption and the selectivity of the proposed scheme. http://hdl.handle.net/2268/145093 Title: Exploiting Localization for Faster Power System Dynamic Simulations <br/> <br/>Author, co-author: Aristidou, Petros; Fabozzi, Davide; Van Cutsem, Thierry <br/> <br/>Abstract: This paper proposes an algorithm for exploiting the localized response of power system components to accelerate dynamic simulations. During the simulation, components marginally participating to the system dynamics are characterized as latent and their dynamic models are replaced by much simpler equivalents. At the same time, components with significant dynamic activity are characterized as active and their original dynamic models are used. Based on the criterion proposed, components switch status between active and latent to increase performance while retaining accuracy. Two realistic test systems, a medium-scale and a large-scale, are used for the performance evaluation of the proposed method. http://hdl.handle.net/2268/145092 Title: Dynamic Simulations of Combined Transmission and Distribution Systems using Decomposition and Localization <br/> <br/>Author, co-author: Aristidou, Petros; Van Cutsem, Thierry <br/> <br/>Abstract: Simulating a power system with both transmission and distribution networks modeled is a challenging task. On the one hand, it is difficult to set up equivalents restituting the dynamic behavior of aggregated loads and distributed generation units. On the other hand, representing all distribution networks in detail is computationally very demanding. In this paper, the combination of a domain-decomposition approach with the exploitation of the localized nature of power system responses to disturbances is proposed. Distribution networks marginally participating to the system dynamics are automatically replaced by simple models, while the others are simulated with full detail, thereby preserving simulation accuracy. http://hdl.handle.net/2268/144854 Title: Prospects of application to the French system of fast methods for transient stability and voltage security assessment <br/> <br/>Author, co-author: Euxibie, Edwige; Goubin, Michel; Heilbronn, Bertrand; Wehenkel, Louis; Xue, Yusheng; Van Cutsem, Thierry; Pavella, Mania