Disseny d’un programa que assisteix en la seqüenciació de peces de taller basats en mètodes heurístics

El GREP (grup de recerca de producte, procés i producció) de la UdG actualmentdisposa d’una eina informàtica desenvolupada en un PFC del 2003 que li permet fer la seqüenciació de la producció d’un taller mecànic amb un màxim de cinc productes, un nombre definit de possibles rutes de fabricació per a cada producte i tres màquines. Aquesta eina és molt resolutiva per a aquests casos, ja que estudia totes les possibilitats i les comprova una per una. No obstant aquest fet presenta una sèrie de limitacions com són el temps d’execució doncs al comprovar totes les seqüències té un elevat cost computacional i la rigidesa del sistema doncs no ens permet seqüenciar més productes ni més màquines. Per tal de donar solució a aquest problema es planteja generar una nova eina informàtica a partir de l’actual però que permeti seqüenciar més peces sense ocupar tanta memòria per així implementar-hi futures millores com el temps de preparació etc... Per a desenvolupar l’eina informàtica s’han utilitzat mètodes heurístics, concretament dos que són: algoritmes genètics i cerca TABU. Aquests mètodes destaquen perquè no busquen totes les combinacions possibles sinó que estudien una sèrie de combinacions i utilitzant mètodes de creuament i generació d’entorns busquen una solució

Desenvolupament d’una aplicación web per a la gestió d’un taller mecànic

Collsaplana Motor SL, és un taller mecànic situat a Vilablareix, al costat de Girona. El taller, a part de fer tot tipus de reparacions mecàniques, està especialitzat en la reparació de caixes de canvis automàtiques i manuals, vehicles clàssics, competició. Els clients són particulars, empreses o altres tallers mecànics, normalment de la província.Una aplicació per aquest negoci ha de ser senzilla i pràctica, per a què qualssevol mecànic, sense gaires coneixements d'informàtica, la pugui utilitzar i portar una bona gestió del taller. L’objectiu del projecte és desenvolupar l’anàlisi, disseny i implementació d’una aplicació per a la gestió de l’empresa. L’aplicació té com a propòsit gestionar els usuaris de l'aplicació, clients, vehicles, recanvis, ordres de reparació, pressupostos, albarans i factures

Evaluación ergonómica: Jefe de taller mecánico

El presente documento tiene como objetivo analizar los riesgos a los que se ven sometidos los trabajadores de un pequeño taller mecánico. Para ello se planificó una evaluación de riesgos ergonómica la cual se ejecutó dentro de unos plazos marcados.El análisis está basado en la detección de las situaciones de riesgo mediante la observación in-situ del desarrollo del trabajo. Con esa finalidad se realizaron dos visitas al taller. La primera de ellas, tenía como objetivo detectar aquellas tareas que su ejecución representaba un riesgo para la salud del trabajador. Una vez detectadas las tareas, y previamente a la segunda visita, se realizó un pequeño estudio para determinar qué métodos ergonómicos se emplearían para realizar el estudio, conociendo de esa manera, que datos serían necesarios recoger al realizar una segunda visita. Seguidamente, se realizó una segunda visita al taller para realizar la observación de las tareas concretada previamente, y la medición de los datos.Finalmente, se procedió a procesar toda la información siguiendo las instrucciones pautadas por los métodos ergonómicos, comparando los resultados obtenidos con los niveles de riesgo admisibles, para extraer unas conclusiones del estudio, las cuales definían las condiciones laborales en las que se encontraba el trabajador. Como muchas de ellas, eran prácticamente inevitables para la ejecución de la tarea, se estudiaron una serie de medidas preventivas para reducir el nivel de riesgo. Una vez analizadas, fueron explicadas a los trabajadores mediante una pequeña formación con la finalidad de que las condiciones de trabajo mejoraran.

Casolà o industrial?: estudi organolèptic i microbiològic de la vida útil del pernil cuit

Treball de recerca realitzat per un alumne d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. Aquest treball tracta sobre el temps de garantia o de vida útil d’un producte alimentari i està basat en esbrinar quin és el millor mètode o envàs per conservar el pernil cuit llescat durant la seva vida útil, per tal que es mantinguin les propietats organolèptiques i microbiològiques inicials de l’aliment durant el màxim de temps possible. Per comparar envasos he utilitzat els industrials (envàs al buit i envàs en atmosfera) i els envasos que podem trobar quan comprem un producte llescat en el mostrador d’una botiga o supermercat. Per a fer l’estudi doncs s’ha utilitzat el pernil cuit, conegut com a pernil dolç, un dels productes més consumits per la societat actual. El pernil ha estat tractat en tres situacions diferents: llescat en una màquina de carnisseria i envasat en mètodes de conservació domèstics, llescat en màquines industrials i envasat en diferents envasos (al buit i en atmosfera modificada) utilitzats per les grans empreses i llescat en màquines industrials i envasat al buit sotmès a un tractament amb altes pressions. Després d’aquests processos s’ha realitzat un estudi de vida útil, és a dir, s’ha analitzat el producte al laboratori, amb l’objectiu de trobar quin és el millor envàs per a la conservació del pernil cuit.

An empirical study of machine learning techniques applied to image watermarking

A study of how the machine learning technique, known as gentleboost, could improve different digital watermarking methods such as LSB, DWT, DCT2 and Histogram shifting.

Towards a user-friendly webservice architecture for statistical machine translation in the PANACEA project

This paper presents a webservice architecture for Statistical Machine Translation aimed at non-technical users. A workfloweditor allows a user to combine different webservices using a graphical user interface. In the current state of this project,the webservices have been implemented for a range of sentential and sub-sententialaligners. The advantage of a common interface and a common data format allows the user to build workflows exchanging different aligners.

A polynomial algorithm for special case of the one-machine scheduling problem with time-lags

The standard one-machine scheduling problem consists in schedulinga set of jobs in one machine which can handle only one job at atime, minimizing the maximum lateness. Each job is available forprocessing at its release date, requires a known processing timeand after finishing the processing, it is delivery after a certaintime. There also can exists precedence constraints between pairsof jobs, requiring that the first jobs must be completed beforethe second job can start. An extension of this problem consistsin assigning a time interval between the processing of the jobsassociated with the precedence constrains, known by finish-starttime-lags. In presence of this constraints, the problem is NP-hardeven if preemption is allowed. In this work, we consider a specialcase of the one-machine preemption scheduling problem with time-lags, where the time-lags have a chain form, and propose apolynomial algorithm to solve it. The algorithm consist in apolynomial number of calls of the preemption version of the LongestTail Heuristic. One of the applicability of the method is to obtainlower bounds for NP-hard one-machine and job-shop schedulingproblems. We present some computational results of thisapplication, followed by some conclusions.

Beyond Smith's rule: An optimal dynamic index, rule for single machine stochastic scheduling with convex holding costs

Most research on single machine scheduling has assumedthe linearity of job holding costs, which is arguablynot appropriate in some applications. This motivates ourstudy of a model for scheduling $n$ classes of stochasticjobs on a single machine, with the objective of minimizingthe total expected holding cost (discounted or undiscounted). We allow general holding cost rates that are separable,nondecreasing and convex on the number of jobs in eachclass. We formulate the problem as a linear program overa certain greedoid polytope, and establish that it issolved optimally by a dynamic (priority) index rule,whichextends the classical Smith's rule (1956) for the linearcase. Unlike Smith's indices, defined for each class, ournew indices are defined for each extended class, consistingof a class and a number of jobs in that class, and yieldan optimal dynamic index rule: work at each time on a jobwhose current extended class has larger index. We furthershow that the indices possess a decomposition property,as they are computed separately for each class, andinterpret them in economic terms as marginal expected cost rate reductions per unit of expected processing time.We establish the results by deploying a methodology recentlyintroduced by us [J. Niño-Mora (1999). "Restless bandits,partial conservation laws, and indexability. "Forthcomingin Advances in Applied Probability Vol. 33 No. 1, 2001],based on the satisfaction by performance measures of partialconservation laws (PCL) (which extend the generalizedconservation laws of Bertsimas and Niño-Mora (1996)):PCL provide a polyhedral framework for establishing theoptimality of index policies with special structure inscheduling problems under admissible objectives, which weapply to the model of concern.

Shallow-transfer rule-based machine translation for Czech to Polish

This article describes the developmentof an Open Source shallow-transfer machine translation system from Czech to Polish in theApertium platform. It gives details ofthe methods and resources used in contructingthe system. Although the resulting system has quite a high error rate, it is still competitive with other systems.

Automatic acquisition of Named Entities for Rule-Based Machine Translation

This paper proposes to enrich RBMTdictionaries with Named Entities(NEs) automatically acquired fromWikipedia. The method is appliedto the Apertium English-Spanishsystem and its performance comparedto that of Apertium with and withouthandtagged NEs. The system withautomatic NEs outperforms the onewithout NEs, while results vary whencompared to a system with handtaggedNEs (results are comparable forSpanish to English but slightly worstfor English to Spanish). Apart fromthat, adding automatic NEs contributesto decreasing the amount of unknownterms by more than 10%.

Taking on new challenges in multi-word unit processing for Machine Translation

This paper discusses the qualitativecomparative evaluation performed on theresults of two machine translation systemswith different approaches to the processing ofmulti-word units. It proposes a solution forovercoming the difficulties multi-word unitspresent to machine translation by adopting amethodology that combines the lexicongrammar approach with OpenLogos ontologyand semantico-syntactic rules. The paper alsodiscusses the importance of a qualitativeevaluation metrics to correctly evaluate theperformance of machine translation engineswith regards to multi-word units.

A Widely Used Machine Translation Service and its Migration to a Free/Open-Source Solution : the Case of Softcatalà

Softcatalà is a non-profit associationcreated more than 10 years ago to fightthe marginalisation of the Catalan languagein information and communicationtechnologies. It has led the localisationof many applications and thecreation of a website which allows itsusers to translate texts between Spanishand Catalan using an external closed-sourcetranslation engine. Recently,the closed-source translation back-endhas been replaced by a free/open-sourcesolution completely managed by Softcatalà: the Apertium machine translationplatform and the ScaleMT web serviceframework. Thanks to the opennessof the new solution, it is possibleto take advantage of the huge amount ofusers of the Softcatalà translation serviceto improve it, using a series ofmethods presented in this paper. In addition,a study of the translations requestedby the users has been carriedout, and it shows that the translationback-end change has not affected theusage patterns.

Hybrid model of a double-fed induction machine and back-to-back converter

This report details the port interconnection of two subsystems: a power electronics subsystem (a back-to-back AC/AC converter (B2B), coupled to a phase of the power grid), and an electromechanical subsystem (a doubly-fed induction machine (DFIM), coupled mechanically to a flywheel and electrically to the power grid and to a local varying load). Both subsystems have been essentially described in previous reports (deliverables D 0.5 and D 4.3.1), although some previously unpublished details are presented here. The B2B is a variable structure system (VSS), due to the presence of control-actuated switches: however from a modelling and simulation, as well as a control-design, point of view, it is sensible to consider modulated transformers (MTF in the bond-graph language) instead of the pairs of complementary switches. The port-Hamiltonian models of both subsystems are presents and coupled through a power-preserving interconnection, and the Hamiltonian description of the whole system is obtained; detailed bond-graphs of all the subsystems and the complete system are provided.

Energy-based modelling and simulation of the interconnection of a back-to-back converter and a doubly-fed induction machine

This paper describes the port interconnection of two subsystems: a power electronics subsystem (a back-to-back AC/CA converter (B2B), coupled to a phase of the power grid), and an electromechanical subsystem (a doubly-fed induction machine (DFIM). The B2B is a variable structure system (VSS), due to presence of control-actuated switches: however, from a modelling simulation, as well as a control-design, point of view, it is sensible to consider modulated transformers (MTF in the bond graph language) instead of the pairs of complementary switches. The port-Hamiltonian models of both subsystems are presented and, using a power-preserving interconnection, the Hamiltonian description of the whole system is obtained; detailed bond graphs of all subsystems and the complete system are also provided. Using passivity-based controllers computed in the Hamiltonian formalism for both subsystems, the whole model is simulated; simulations are run to rest the correctness and efficiency of the Hamiltonian network modelling approach used in this work.

Preferred Spatial Frequencies for Human Face Processing Are Associated with Optimal Class Discrimination in the Machine

Psychophysical studies suggest that humans preferentially use a narrow band of low spatial frequencies for face recognition. Here we asked whether artificial face recognition systems have an improved recognition performance at the same spatial frequencies as humans. To this end, we estimated recognition performance over a large database of face images by computing three discriminability measures: Fisher Linear Discriminant Analysis, Non-Parametric Discriminant Analysis, and Mutual Information. In order to address frequency dependence, discriminabilities were measured as a function of (filtered) image size. All three measures revealed a maximum at the same image sizes, where the spatial frequency content corresponds to the psychophysical found frequencies. Our results therefore support the notion that the critical band of spatial frequencies for face recognition in humans and machines follows from inherent properties of face images, and that the use of these frequencies is associated with optimal face recognition performance.