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.

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have been essentially described in previous reports (deliverables D 0.5 and D 4.3.1), although some previously unpublished details are presented here.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.

Correlating trainees' translating performance with the quality of their metacognitive self-evaluation

This paper presents a study of correlations between the performance of trainee translators, according to their teacher’s assessment, and the quality of their self-evaluation, according to their answers to metacognitive questionnaires. Two case-studies of two consecutive editions of a course in general translation from German into Spanish are dealt with. The course involved the use of post-translation metacognitive questionnaires designed to help trainees to evaluate their translating. A selection of the questionnaires (from the strongest and the weakest performances by students for each course edition) is considered. The study focuses on one item in these questionnaires that has to do with identifying translation problems and justifying their solutions. An interpretive analysis of the trainees’ answers for this questionnaire item reveals that the best-performing students were more strategically and translationally aware in self-evaluating their own translating. Our conclusions are based on considering six parameters from the analysis of the trainees’ answers, which are tentatively regarded as indicative of the quality of their self-evaluation.

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.

Servei de rutes basat en Open Source Routing Machine

Aquesta memòria descriu la preparació, l'execució i els resultats obtinguts d'implementar un sistema calculador de rutes. El projecte Open Source Routing Machine és un motor calculador de rutes d'alt rendiment que utilitza les dades de OpenStreetMaps per calcular el camí més curt entre dos punts. En aquest projecte final no únicament es volen utilitzar les dades OpenStreetMap sinó que també es pretenen utilitzar dades pròpies en format shapefile i poder visualitzar-los en un visor web. Aquest visor permet a l'usuari, de forma senzilla, sol•licitar rutes al servidor OSRM creat, obtenint la ruta desitjada en molt pocs milisegons

A Gendered Voice in Translation: Translating Like a Feminist

This paper addresses some of the challenges inherent in finding and showing a gendered voice in translation. The starting point is my own experience as a feminist translator of both feminist and non-feminist texts. Textual practices like translating necessarily interact with current theoretical debates. In turn, theoretical writing on feminism enriches and informs one’s translating activity. This interplay between theoretical models and textual practices was particularly made evident to me as I rendered Essentially speaking, by Diana Fuss, into Catalan. In this article I intend to transcend anecdotes of translating individual texts and consider how translating equals rewriting oneself; it involves rethinking writing practices. I will specifically address the rethinking of (1) one’s identity when translating ‘like’ a feminist, (2) performativity in gender and in translation, and (3) agency and (In)visibility.