http://www.recercat.cat:80/handle/2072/2245 Mon, 21 May 2012 18:46:50 GMT 2012-05-21T18:46:50Z http://www.recercat.cat:80/bitstream/id/35023/ http://www.recercat.cat:80/handle/2072/2245 http://www.recercat.cat:80/handle/2072/196089 Thermal radiation from vertical jet fires Palacios, Adriana; Muñoz, Miguel; Darbra Roman, Rosa Maria; Casal Fàbrega, Joaquim Geometric and thermal data, obtained from a series of large outdoor jet fire experiments, were used to estimate the thermal radiation intensity from the flames towards targets located at diverse distances. Vertical turbulent sonic and subsonic exit velocity propane jet fires, up to 10.3 m in length released in still air, were studied. The temperatures of the flame surface and the surface emissive power of the flame were also analysed by processing infrared images. Thermal radiation intensity was estimated by applying the solid flame model in both one-zone and multiple-zone configurations (taking into account the variation of surface emissive power), considering the flame as a cylinder defined by the 800 K isotherm. Experimental and predicted thermal radiation intensity values were compared. http://www.recercat.cat:80/handle/2072/196089 http://www.recercat.cat:80/handle/2072/196088 Modeling and solving a variant of the mixed-model sequencing problem with work overload minimisation and regularity constraints. An application in Nissan’s Barcelona Plant Bautista Valhondo, Joaquín; Cano Pérez, Alberto; Alfaro Pozo, Rocío In this paper, we present an extension to the mixed-model sequencing problem with work overload minimisation (MMSP-W) for production lines with serial workstations and parallel homogeneous processors. The extension is intended to meet the industrial need to sequence various products so that the work required and completed at the workstations over time is as constant as possible. Several approaches are proposed to formulate the problem, giving rise to different models. Four models are selected, and their performances are compared after running the Gurobi solver, using instances from the literature and a case study of the Nissan powertrain plant in Barcelona. http://www.recercat.cat:80/handle/2072/196088 http://www.recercat.cat:80/handle/2072/196087 El paisaje portuario en viñetas Ojeda Rodríguez, Jordi The term “comic” is used to refer to a strip or sequenceof cartoons/vignettes with or without text that tell astory (however short it might be) in which at least onecharacter appears in more than one vignette. The comicis recognised as the ninth art form, and there are a greatvariety of types and names, depending on the sourceand the format: historieta, tebeo, manga, bande dessinée,banda desenhado, fumetti or comic-book,amongst others. Virtually every country has its owncharacters and collections, and those that deal with universalsubject matter or historical questions transcendfrontiers and gradually become known the world over,the following being such examples: Tintin, Asterix, Mortadeloand Filemón, Corto Maltés, Superman, Spidermanor Flash Gordon, which have now become real classics.Comics undoubtedly have the ability to convey knowledgeand feelings. Their educational value enables childrenand adults alike to gain insight into differentareas of reality, in the past and present, dealing withalmost every aspect of life: nature, mankind, technology,legends, cultures, history, adventures, etc., allowingthe reader to explore the boundaries between fictionand reality, even heralding a future that can prove tobe most unexpected and surprising. Comics makelearning easier and stimulate the imagination, andthey are an excellent resource for developing creativethinking and artistic sensitivity, while at the same timeencouraging the reader to adopt a critical stance. Theycan be suitable instruments for creatively and intelligentlyexplaining the world of ports and the sea, andto make this accessible to all types of potential reader.This is particularly the case where the port landscape isconcerned, because of the nature of the artistic disciplinethat is deeply rooted in the way cartoons orvignettes are illustrated. http://www.recercat.cat:80/handle/2072/196087 http://www.recercat.cat:80/handle/2072/196086 Input observability analysis of Fixed speed wind turbine García Planas, María Isabel This paper deals with the concept of input observability in a fixed speed wind turbine. A linear systemhas been calculated from the nonlinear equations of the squirrel cage induction generator, supposing it connecteddirectly to the grid and assuming a steady state operating point. The observability of the input from the outputof the system could be an interesting way to know if its possible to develop some new controls without introducespecial sensors in the system. Furthermore, it is interesting to analyse which is the parameter variation margin ofthe wind turbine from input-observable state to non-input observable, in order to obtain some restrictions to designfuture controllers, or limit the operating points http://www.recercat.cat:80/handle/2072/196086 http://www.recercat.cat:80/handle/2072/195977 Evaluación de una experiencia piloto de adaptación al EEES Morón Tarifa, Miguel; Mata Pou, Mireia; Gallardo León, Juan Antonio La titulación Ingeniería Técnica Industrial Mecánica de la Escuela Universitaria de Ingeniería Técnica Industrial de Terrassa participa desde el curso 2005-06 en un plan piloto de adaptación al EEES promovido por el Departamento de Universidades de la Generalitat de Catalunya. Durante el primer año de experiencia, se puso en marcha un sistema de seguimiento de su implantación y resultados. Este sistema, tenía como ejes básicos las reuniones de seguimiento entre el profesorado participante y la subdirección responsable del plan, los informes de asignatura redactados por el profesorado, y la elaboración de un modelo de encuesta para los estudiantes orientado a conocer su nivel de satisfacción en relación a los resultados de la docencia y el uso que han hecho de las competencias incluidas en el perfil de formación del titulo. En la ponencia expondremos los resultados obtenidos, y las acciones correctoras implantadas para el siguiente curso, distinguiendo entre el ámbito de la gestión y control del plan y el ámbito de la docencia y la innovación educativa. http://www.recercat.cat:80/handle/2072/195977 http://www.recercat.cat:80/handle/2072/195976 Synthesis, Langmuir and Langmuir-Blodgett films of a calix[7]arene ethyl ester Torrent Burgués, Juan; Vocanson, Francis; Pérez González, Juan Jesús; Errachid, Abdelhamid http://www.recercat.cat:80/handle/2072/195976 http://www.recercat.cat:80/handle/2072/195975 Estudio ACV del cableado de un vehículo Amante García, Beatriz; Gonçalves Ageitos, María; Ollé, Tania En este artículo se realizará un estudio de los diferentes aislantes que se pueden utilizar para la fabricación de cableado de cobre unifilar para el sector del automóvil. Se analizará cuál de los aislantes a mismas prestaciones supone un menor consumo energético y menores emisiones de CO2 a lo largo de su ciclo de vida. http://www.recercat.cat:80/handle/2072/195975 http://www.recercat.cat:80/handle/2072/195974 Is there a hidden hole in type la supernova remnants? García Senz, Domingo; Badenes, Carles; Serichol, N. In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium.Ouraim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh–Taylor instability grows faster, leading to plumes that approach the edge of the forward shock.We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity. http://www.recercat.cat:80/handle/2072/195974 http://www.recercat.cat:80/handle/2072/195973 Improving smoothed particle hydrodynamics with an integral approach to calculating gradients García Senz, Domingo; Cabezón Gómez, Rubén Martín; Escartín Vigo, José Antonio Context. The smoothed particle hydrodynamics (SPH) technique is a well-known numerical method that has been applied to simulatethe evolution of a wide variety of systems. Modern astrophysical applications of the method rely on the Lagrangian formulation offluid Euler equations, which is fully conservative. A different scheme, based on a matrix approach to the SPH equations is currently being used in computational fluid dynamics. These matrix formulations achieve better interpolations of the physical magnitudes but they are, in general, not fully conservative. The matrix approach to the Euler equations has never been used in astrophysics.Aims. We develop and test a fully conservative SPH scheme based on a tensor formulation that can be applied to simulate astrophysical systems.Methods. In the proposed scheme, derivatives are calculated from an integral expression that leads to a tensor (instead of a vectorial) estimation of gradients and reduces to the standard formulation in the continuum limit. The new formulation improves the interpolation of physical magnitudes, leading to a set of conservative equations that resembles those of standard SPH. The resulting scheme is verified using a variety of well-known tests, all of them simulated in two dimensions. We also discuss an application of the proposed tensor method to astrophysics by simulating the stability of a Sun-like polytrope calculated in three dimensions.Results. The proposed scheme is able to improve the results of standard SPH in the two-dimensional tests, especially in the simulation of subsonic hydrodynamic instabilities. Our results for the stability of the Sun-like polytrope suggest that the new method can be used in astrophysics to carry out three-dimensional calculations with a computational cost that is only slightly higher (i.e. ≤50% for a serialcode) than that of a standard SPH formulation.Conclusions. A formalism based on a matrix approach to Euler SPH equations was developed and checked. The new scheme ismore accurate because of the re-normalization imposed on the interpolations, which is fully conservative and probably less prone to undergo the tensile instability. The analysis of several test cases suggest that the method may improve the simulation of both subsonic and supersonic systems. An application of the tensor method to astrophysics is, for the first time, successfully carried out. Theseencouraging results indicates that more work should be invested in the applications of matrix SPH formulations to astrophysics. http://www.recercat.cat:80/handle/2072/195973 http://www.recercat.cat:80/handle/2072/195972 Seismic performance of buildings with thin RC bearing walls Gonzáles Fernández, Helbert; López Almansa, Francisco up to five stories) with thin RC shear-walls have been constructed for low-cost dwellings in Bolivia, Colombia, Ecuador, Mexico, Peru,Venezuela, and other countries located in seismic-prone regions. These walls are 10 cm thick and their reinforcement consists mainly ofa single layer of welded wire mesh. This construction technology offers two main advantages: economy and rapidity of construction.These buildings do not fulfill the international seismic codes but some national regulations are less demanding, not preventing the use ofthin bearing walls. These buildings might be vulnerable to earthquakes because of their low ductility, the insufficiency of theexperimental information, the absence of observed damages and, in some cases, poor construction quality. This work describes the initialsteps of a wider research aiming at providing reliable seismic design guidelines for thin-wall buildings; the initial objectives areanalyzing the seismic performance of these buildings, proposing preliminary design criteria and identifying further research needs. Thisresearch focuses on buildings located in Peru, being representative of the situations in the other countries. The vulnerability isnumerically evaluated by push-over and nonlinear time history analyses; the structural parameters are obtained from available testinginformation. The obtained results show that the seismic strength of the analyzed buildings is insufficient; however, minor changes in thestructural design might improve significantly their seismic performance. Economical and easy-to-implement design recommendationsare issued. http://www.recercat.cat:80/handle/2072/195972 http://www.recercat.cat:80/handle/2072/195971 Spectrum usage models for the analysis, design and simulation of cognitive radio networks López Benítez, Miguel; Casadevall Palacio, Fernando José This chapter presents a comprehensive set of spectrum occupancy models specifically envisaged for the analysis, design and simulation of cognitive radio systems. The presented models have been proven to accurately capture and reproduce the statistical properties of spectrum occupancy patterns in real systems. The chapter begins with the description of various time-dimension modeling approaches (in discrete and continuous time) along with models for time-correlation properties. Subsequently, joint time-frequency models as well as space-dimension models are explained in detail. Finally, the chapter concludes with a discussion on the combination and integration of the presented models into a unified modeling approach where the time, frequency and space dimensions of spectrum usage can be modeled simultaneously. http://www.recercat.cat:80/handle/2072/195971 http://www.recercat.cat:80/handle/2072/195970 Simultaneous speech detection with spatial features for speaker diarization Zelenak, Martin; Segura, Carlos; Luque, Jordi; Hernando Pericás, Francisco Javier Simultaneous speech poses a challenging problem for conventional speaker diarization systems. In meeting data, a substantial amount of missed speech error is due to speaker overlaps, since usually only one speaker label per segment is assigned. Furthermore, simultaneous speech included in training data can lead to corrupt speaker models and thus worse segmentation performance. In this paper, we propose the use of three spatial cross-correlation-based features together with spectral information for speaker overlap detection on distant microphones. Different microphone-pair data are fused by means of principal component analysis. We have obtained an improvement of the speaker diarization system over the baseline by discarding overlap segments from model training and assigning two speaker labels to them according to likelihoods in Viterbi decoding. In experiments conducted on the AMI Meeting corpus, we achieve a relative DER reduction of 11.2% and 17.0% for single- and multi-site data, respectively. The improvement of clustering with techniques such as beamforming and TDOA-feature stream also leads to a higher effectiveness of the overlap labeling algorithm. Preliminary experiments with NIST RT data show DER improvement on the RT'09 meeting recordings as well. http://www.recercat.cat:80/handle/2072/195970 http://www.recercat.cat:80/handle/2072/195969 Topological light bullets supported by spatiotemporal gain Lobanov, Valery E.; Borovkova, Olga V.; Kartashov, Yaroslav; Vysloukh, Victor A.; Torner Sabata, Lluís We reveal that the competition among diffraction, cubic nonlinearity, two-photon absorption, and gain localized in both space and time results in arrest of collapse, suppression of azimuthal modulation instabilities for spatiotemporal wave packets, and formation of stable three-dimensional light bullets. We show that Gaussian spatiotemporal gain landscapes support bright, fundamental light bullets, while gain landscapes featuring a ringlike spatial and a Gaussian temporal shapes may support stable vortex bullets carrying topological phase dislocations. http://www.recercat.cat:80/handle/2072/195969 http://www.recercat.cat:80/handle/2072/195968 Enhancing the sensitivity and robustness of label-free imaging systems via stimulated Raman adiabatic passage León Montiel, R.D.J.; Pérez Torres, Juan We show that the sensitivity and robustness of a label-free optical imaging technique based on stimulated Raman scattering (SRS) can be enhanced by using resonant optical transitions in a Raman adiabatic passage scheme. Our approach is based on the consideration that any enhancement of the flow of energy between two light beams involved in the SRS process is related to an increase in atomic population transfer between the energy levels of interest. One can thus profit from techniques developed in quantum optics to maximize such atomic population transfer for enhancing the sensitivity and robustness of optical imaging techniques. http://www.recercat.cat:80/handle/2072/195968 http://www.recercat.cat:80/handle/2072/195967 Solitons supported by spatially inhomogeneous nonlinear losses Borovkova, Olga V.; Kartashov, Yaroslav; Vysloukh, Victor A.; Lobanov, Valery E.; Malomed, Boris A.; Torner Sabata, Lluís We uncover that, in contrast to the common belief, stable dissipative solitons exist in media with uniform gain in the presence of nonuniform cubic losses, whose local strength grows with coordinate η (in one dimension) faster than |η| . The spatially-inhomogeneous absorption also supports new types of solitons, that do not exist in uniform dissipative media. In particular, single-well absorption profiles give rise to spontaneous symmetry breaking of fundamental solitons in the presence of uniform focusing nonlinearity, while stable dipoles are supported by double-well absorption landscapes. Dipole solitons also feature symmetry breaking, but under defocusing nonlinearity. http://www.recercat.cat:80/handle/2072/195967 http://www.recercat.cat:80/handle/2072/195966 High hardness, low Young's modulus and low friction of nanocrystalline ZrW2 Laves phase and Zr1-xWx thin films Horwat, David; Jiménez Piqué, Emilio; Pierson, J.F.; Migot, A.; Dehmas, M.; Anglada Gomila, Marcos Juan Zr1−xWx nanocrystalline films of Zr-W solid solutions and ZrW2 Laves phase were synthesized by magnetron co-sputtering. Large values of the H/E ratio up to 0.09 are observed for grain sizes in the nanometer range along with a hardness above 10 GPa and Young's modulus below 230 GPa. H/E values are correlated with the developed surface of grain boundaries suggesting an elastic deformation mostly handled by the grain boundaries. This is associated to friction coefficients comparable to those of metallic glass surfaces. In contrast to fragile bulk Laves phases, no cracks were detected at the film surface after indentation and scratch test of nanocrystalline ZrW2. The friction coefficient of such films against diamond tip was in the range 0.08–0.15, similarly to metallic glass surfaces. http://www.recercat.cat:80/handle/2072/195966 http://www.recercat.cat:80/handle/2072/195965 Mapping the intellectual structure of entrepreneurship research: revisiting the invisible college Montiel Campos, Héctor; Solé Parellada, Francesc; Palma, Yarissa http://www.recercat.cat:80/handle/2072/195965 http://www.recercat.cat:80/handle/2072/195964 The NMMB/BSC-CTM: a multiscale online chemical weather prediction system Jorba, O.; Pérez García-Pando, Carlos; Haustein, Karsten; Janjic, Z.; Baldasano Recio, José M. (José María); Dabdub, Donald; Badia Moragas, Alba; Spada, M. Abstract: The model NMMB/BSC-CTM is a new fully on-line chemical weather prediction system under development at the Earth SciencesDepartment of the Barcelona Supercomputing Center in collaboration with several research institutions. The basis of the development is theNCEP new global/regional Nonhydrostatic Multiscale Model on the B grid (NMMB). Its unified nonhydrostatic dynamical core allowsregional and global simulations and forecasts. A mineral dust module has been coupled within the NMMB. The new system, NMMB/BSCDUST,simulates the atmospheric life cycle of the eroded desert dust. The main characteristics are its on-line coupling of the dust schemewith the meteorological driver, the wide range of applications from meso to global scales, and the dust shortwave and longwave radiativefeedbacks on meteorology. In order to complement such development, the BSC works also in the implementation of a fully on-line gas-phasechemical mechanism. Chemical species are advected and mixed at the corresponding time steps of the meteorological tracers using the samenumerical scheme of the NMMB. Advection is Eulerian, positive definite and monotone. The final objective of the work is to develop a fullychemical weather prediction system, namely NMMB/BSC-CTM, able to resolve gas-aerosol-meteorology interactions from global to localscales. Future efforts will be oriented to incorporate a multi-component aerosol module within the system with the aim to solve the life-cycleof relevant aerosols at global scale (dust, sea salt, sulfate, black carbon and organic carbon). In the present contribution we describe the statusof development of the system and first evaluation results of the gas-phase chemistry. http://www.recercat.cat:80/handle/2072/195964 http://www.recercat.cat:80/handle/2072/195963 Assessing the environmental impact of biobleaching: effects of the operational conditions Valls Vidal, Cristina; Quintana, Elisabet; Roncero Vivero, Ma. Blanca (María Blanca) The environmental impact of enzyme bleaching stages applied to oxygen-delignified eucalypt kraft pulp was assessed via the chemical oxygen demand (COD), color, absorbance spectrum, residual enzyme activity and Microtox toxicity of the effluents from a laccase–HBT (1-hydoxybenzotriazole) treatment. The influence of the laccase and HBT doses, and reaction time, on these effluent properties was also examined. The laccase dose was found to be the individual variable most strongly affecting COD, whereas the oxidized form of HBT was the main source of increased color and toxicity in the effluents. Moreover, it inactivated the enzyme. Oxidation of the mediator was very fast and essentially dependent on the laccase dose. Using the laccase–mediator treatment after a xylanase stage improved pulp properties without affecting effluent properties. This result holds great promise with a view to the industrial implementation of biobleaching sequences involving the two enzymes in the future. http://www.recercat.cat:80/handle/2072/195963 http://www.recercat.cat:80/handle/2072/195962 Local reactive power control methods for overvoltage prevention of distributed solar inverters in low-voltage grids Demirok, Erhan; Casado Gonzalez, P.; Frederiksen, K.H.B.; Sera, Dezso; Rodríguez Cortés, Pedro; Teodorescu, Remus The main objective of this study is to increase the penetrationlevel of photovoltaic (PV) power production in low-voltage(LV) grids by means of solar inverters with reactive power controlcapability. This paper underlines weak points of standard reactivepower strategies which are already imposed by certain gridcodes, and then, the study introduces a new reactive power controlmethod that is based on sensitivity analysis. The sensitivity analysisshows that the same amount of reactive power becomes moreeffective for grid voltage support if the solar inverter is locatedat the end of a feeder. Based on this fundamental knowledge, alocation-dependent power factor set value can be assigned to eachinverter, and the grid voltage support can be achieved with lesstotal reactive power consumption. In order to prevent unnecessaryreactive power absorption from the grid during admissible voltagerange or to increase reactive power contribution from the invertersthat are closest to the transformer during grid overvoltage condition,the proposed method combines two droop functions that areinherited from the standard cosϕ(P) and Q(U) strategies. Its performancecomparison in terms of grid losses and voltage variationwith different reactive power strategies is provided by modelingand simulating a real suburban LV network. http://www.recercat.cat:80/handle/2072/195962 http://www.recercat.cat:80/handle/2072/195961 Design optimization of storage facilities taking into account the domino effect Bernechea, Esteban; Arnaldos Viger, Josep Storing hazardous substances is a process that entrails high risk, and in which many resources are spent in the planning of safety measures; however, safety could be included at the initial stages of the design of this type of installations, by optimizing the number of tanks that are used to store the substance. The effects and consequences of major accidents are directly proportional to the mass of materials involved in them; therefore, if the mass was divided in more containing units, the consequences at the moment of an accident occurrence would be lesser. However, as more units are used to store a dangerous substance in an installation, the risk of domino effect occurrence at the moment of an accident also increases. The objective of this paper is to develop a methodology that allows finding the optimum number of units that have to be used to store dangerous materials, taking the possibility of domino effect occurrence into account. The proposed methodology is described and applied to a case study as a decision making tool, obtaining results that demonstrate that the design of storage installations can be improved from a risk point of view, by combining quantitative risk analysis and optimization techniques. http://www.recercat.cat:80/handle/2072/195961 http://www.recercat.cat:80/handle/2072/195960 Multi-objective optimization of hazardous substance storage facilities. The decision between risks and costs associated to the project Bernechea, Esteban; Zamarripa, Miguel; Arnaldos Viger, Josep The design storage installations for dangerous substances can be optimized from a safety and risk point of view by combining quantitative risk analysis and mathematical optimization techniques; the consequences of accidents are directly proportional to the mass involved in them, which means that in a storage installation, if the totality of the stored substance is divided into more tanks, the consequences when an accident occurs in any of the units will be less significant than if all the mass was stored in one tank (in installations where there is low possibility of domino effect occurrence). However, as more tanks are used to store the mass, the economical investment will also increase; then, a situation arises between two conflicting objectives, that can be solved through the use of multi objective optimization. http://www.recercat.cat:80/handle/2072/195960 http://www.recercat.cat:80/handle/2072/195959 Interfaces y sistemas en rehabilitación y compensación funcional para la autonomía personal y la terapia clínica Ceres, Ramón; Mañanas Villanueva, Miguel Ángel; Azorín, José María La Bioingeniería constituye un área de trabajo e investigación multidisciplinar entre las ingenierías y la medicina que resulta de un interés humano, social y económico creciente. La automática en particular, en sus aspectos de percepción, modelado, control, monitorización, actuación e interacción, entre otros, ofrece importantes conocimientos y herramientas para abordar los problemas relacionados con el diagnóstico y el seguimiento de patologías, con las necesidades funcionales especiales e igualmente con las diferentes terapias a aplicar. Este tutorial presenta aspectos relacionados con el estado del arte y últimos avances en los siguientes campos: Interfaces para la interacción y comunicación de personas con discapacidad, robótica para la rehabilitación y compensación funcional, y sistemas para la mejora de la terapia clínica http://www.recercat.cat:80/handle/2072/195959 http://www.recercat.cat:80/handle/2072/195958 The entrepreneurial orientation-dominant logic-performance relationship in new ventures: an exploratory quantitative study Montiel Campos, Héctor; Nuño De la Parra, José Pablo; Solé Parellada, Francesc Entrepreneurial Orientation (EO) has received substantial conceptual and empirical attention, representing one ofthe few areas in entrepreneurship research in which a cumulative body of knowledge is developing. Nonetheless,an important message from past research is that simply examining the direct effect of EO on firm performanceprovides an incomplete picture, especially in the case of new ventures. This study examined the influence ofDominant Logic (DL) on the relationship between EO and firm performance. Results based on a sample of 149new manufacturing ventures indicated that DL mediates the EO-performance relationship, and risk taking,aggressiveness and innovativeness had the highest correlations with the internal and external conceptualizationof DL. The empirical evidence suggests that new ventures must foster DL implementing appropriate strategicprocesses in order to maximize the effect of EO on performance. http://www.recercat.cat:80/handle/2072/195958 http://www.recercat.cat:80/handle/2072/195957 An investigation on the design of steel storage rack columns via the direct strength method Casafont Ribera, Miguel; Pastor Artigues, María Magdalena; Roure Fernández. Francesc; Bonada Bo, Jordi; Peköz, Teoman The paper presents an attempt to predict the load carrying capacity of perforatedrack columns by means of the Direct Strength Method (DSM). The investigation is focusedon two different issues: the prediction of the elastic buckling loads of members with multipleperforations, and the evaluation of the accuracy of the current DSM buckling curves whenapplied to rack columns. In relation to the first issue, a model for the calculation of the reducedthickness of the perforated strip to be used in finite strip buckling analysis is developed.Regarding the study of the DSM curves, it is demonstrated that they can be used to accuratelydetermine the strength of rack cross-sections whose failure is governed by distortional bucklingor global buckling (with no significant participation of local buckling). This is an interestingresult because it will allow substituting the distortional buckling tests, that are currentlycarried out in the process of design of these columns, by a simple and easy to apply calculation procedure. http://www.recercat.cat:80/handle/2072/195957 http://www.recercat.cat:80/handle/2072/195956 Task independent minimum confusability training for continuous speech recognition Nogueiras Rodríguez, Albino; Mariño Acebal, José B. (José Bernardo) In this paper, a task independent discriminative training framework for subword units based continuous speech recognition is presented. Instead of aiming at the optimisation of any task independent figure, say the phone classification or recognition rates, we focus our attention to the reduction of the number of errors committed by the system when a task is defined. This consideration leads to the use of a segmental approach based on the minimisation of the confusability over short chains of subword units. Using this framework, a reduction of 32% in the string error rate may be achieved in the recognition of unknown length digit strings using task independent phone like units. http://www.recercat.cat:80/handle/2072/195956 http://www.recercat.cat:80/handle/2072/195955 SDR receiver computational model for application in power control Gómez, Ismael; Marojevic, Vuk; Gelonch Bosch, Antonio José Software-defined radio (SDR) permits dynamic switches of the employed radio access technology (RAT), over-the-air (OTA) software updates, software and hardware reuse. This extended flexibility comes at the price of a higher computing complexity and, in particular, the energy consumption at the receiver. The analysis of the computational profile of signal processing algorithms is of great importance in SDR for understanding the implication on the energy consumption. Several signal processing algorithms show a different profile as a function of the signal quality perceived at the receiver antenna. Therefore, power control policies have an implication on the computational performance of SDR receivers. Understanding the behaviour of these algorithms allows trading transmitted power against receiver energy consumption. This paper presents a model for characterizing the computational profile of Turbo and LDPC decoders and demonstrates is applicability in existing power control strategies. http://www.recercat.cat:80/handle/2072/195955 http://www.recercat.cat:80/handle/2072/195954 Feasibility of vehicle continuous charging in highways Mercadal Playà, Albert; Robusté Anton, Francesc This paper analyzes in a systemic way a taxonomy of technologies that allow “continuous charging” (ConCha) of vehicles while they circulate on highways. Once the menu of available technologies has been described, they are appraised following a multi-criteria method to select the most promising one. This happens to be the Induction Power Transfer system, also called OLEV for on-line electric vehicle, and already in laboratory implementation in Korea. After the description of the system a cost-benefit analysis is performed and applied to a highway in Barcelona, Spain. The conclusion is that the system is already feasible nowadays and it can be even more feasible in the near future, depending upon the vehicle technology cost and energy price. http://www.recercat.cat:80/handle/2072/195954 http://www.recercat.cat:80/handle/2072/195953 Input Observability Analysis of Fixed Speed Wind Turbine García Planas, María Isabel; Domínguez García, José Luis; Mediano Valiente, Begoña This paper deals with the concept of input observability in a fixed speed wind turbine. A linear systemhas been calculated from the nonlinear equations of the squirrel cage induction generator, supposing it connecteddirectly to the grid and assuming a steady state operating point. The observability of the input from the outputof the system could be an interesting way to know if its possible to develop some new controls without introducespecial sensors in the system. Furthermore, it is interesting to analyse which is the parameter variation margin ofthe wind turbine from input-observable state to non-input observable, in order to obtain some restrictions to designfuture controllers, or limit the operating points. http://www.recercat.cat:80/handle/2072/195953 http://www.recercat.cat:80/handle/2072/195952 A discrete bernoulli free boundary problem González Nogueras, María del Mar; Gualdani, Maria; Shagholian, Henrick We consider a free boundary problem for the p-Laplace operatorwhich is related to the so-called Bernoulli free boundary problem.In this formulation, the classical boundary gradient condition is replacedby a condition on the distance between two di erent level surfaces ofthe solution. For suitable scalings our model converges to the classicalBernoulli problem; one of the advantages in this new formulation lies inthe simplicity of the arguments, since one does not need to consider theboundary gradient.We shall study this problem in convex and other regimes, and establishexistence and qualitative theory http://www.recercat.cat:80/handle/2072/195952