Estimation of lean meat content in pig carcasses using X-ray Computed Tomography and PLS regression

Lean meat percentage (LMP) is an important carcass quality parameter. The aim of this work is to obtain a calibration equation for the Computed Tomography (CT) scans with the Partial Least Square Regression (PLS) technique in order to predict the LMP of the carcass and the different cuts and to study and compare two different methodologies of the selection of the variables (Variable Importance for Projection — VIP- and Stepwise) to be included in the prediction equation. The error of prediction with cross-validation (RMSEPCV) of the LMP obtained with PLS and selection based on VIP value was 0.82% and for stepwise selection it was 0.83%. The prediction of the LMP scanning only the ham had a RMSEPCV of 0.97% and if the ham and the loin were scanned the RMSEPCV was 0.90%. Results indicate that for CT data both VIP and stepwise selection are good methods. Moreover the scanning of only the ham allowed us to obtain a good prediction of the LMP of the whole carcass.

Mobile termination and mobile penetration

In this paper, we study how access pricing affects network competition when subscription demand is elastic and each network uses non-linear prices and can apply termination-based price discrimination. In the case of a fixed per minute termination charge, we find that a reduction of the termination charge below cost has two opposing effects: it softens competition but helps to internalize network externalities. The former reduces mobile penetration while the latter boosts it. We find that firms always prefer termination charge below cost for either motive while the regulator prefers termination below cost only when this boosts penetration. Next, we consider the retail benchmarking approach (Jeon and Hurkens, 2008) that determines termination charges as a function of retail prices and show that this approach allows the regulator to increase penetration without distorting call volumes.

Eines interactives per l'aprenentatge de la dinàmica i el control dels convertidors de potència

El projecte s'ha centrat en el disseny i desenvolupament de laboratoris virtuals per a la docència del dispositius i mètodes de gestió d’energia. Això s’ha realitzat a dos nivells clarament diferenciats, el primer grup de laboratoris correspon als convertidors electrònics de potencia i el segon grup de laboratoris correspon a un conjunt de casos d’aplicacions concretes. En el primer grup es descriu el detall del funcionament dels diferents elements mentre que en el segon els descriuen les idees i conceptes bàsics de funcionament. Els laboratoris virtuals de convertidors electrònics de potència inclouen el convertidor elevador (boost), el convertidor reductor (buck), i convertidors acobladors magnèticament. Aquestes permeten estudiar el comportament dinàmica des d’un punt de vista commutat o bé promitjat, les aplicacions incorporen també la possibilitat de sintonitzar els controladors. Aquestes aplicacions han estat desenvolupades per ser un complement per les sessions de pràctiques presencials. Els laboratoris virtuals d’aplicacions, inclouen els sistema de transport metropolità, el vehicle híbrid i els sistemes de gestió de talls transitoris en el subministrament d’energia principalment. Aquestes laboratoris permeten introduir els estudiants de forma qualitativa en els diferents conceptes i tècniques emprades en els sistemes de generació, transport i transformació d’energia. Totes les aplicacions han estat desenvolupades emprant Easy JAVA Simulations, aquesta eina permet desenvolupar laboratoris multiplataforma fàcilment distribuïbles a través d’internet.

Sharpened lower bounds for cut elimination

We present sharpened lower bounds on the size of cut free proofs for first-order logic. Prior lower bounds for eliminating cuts from a proof established superexponential lower bounds as a stack of exponentials, with the height of the stack proportional to the maximum depth d of the formulas in the original proof. Our new lower bounds remove the constant of proportionality, giving an exponential stack of height equal to d − O(1). The proof method is based on more efficiently expressing the Gentzen-Solovay cut formulas as low depth formulas.

PFC J2EE : botiga de Llibres On-Line KIWIX

L'objectiu del present Projecte final de carrera consisteix en la realització d'un dissenye implementació d'un lloc web de venta de llibres al detall.El sistema mostra a l'usuari una sèrie de productes. Tots aquest productespoden ser adquirits per l'usuari prèvia identificació i validació de les dades.

Examining the sustainability issues in UKOER projects : Developing a sustainable OER ecosystem in HE

The development of open educational resources (OERs) is becoming a strategic priority for governments and education institutions around the world, in response to funding cuts and rising costs in educational provision. In the United Kingdom, a government-sponsored Pilot Programme on Open Educational Recourses (JISC/HEA, 2009) was launched in 2009 with an initial budget of £5.7m. This paper reviews the key sustainability issues identified by the projects including the different approaches and models that have been adopted in order to sustain the continuing development and release of OER once funding has ended. The analysis also considers the challenges relating to the development and implementation of policies and processes for sustainable OER practice within institutions and among academics. The paper concludes by drawing on the experiences from the wider United Kingdom and international OER communities to develop a sustainable OER ecosystem model that can facilitate discussions on future development of OER initiatives.

Economic structure and key sectors analysis of greenhouse gas emissions in Uruguay

This paper identifies the key sectors in greenhouse gas emissions of the Uruguayan economy through input-output analysis. This allows to precisely determine the role played by the different productive sectors and their relationship with other sectors in the relation between the Uruguayan productive structure and atmospheric pollution. In order to guide policy design for GHG reduction, we decompose sectors liability between the pollution generated through their own production processes and the pollution indirectly generated in the production processes of other sectors. The results show that all the key polluting sectors for the different contaminants considered are relevant because of their own emissions, except for the sector Motor vehicles and oil retail trade, which is relevant in CO2 emissions because of its pure, both backward and forward, linkages. Finally, the best policy channels for controlling and reducing GHGs emissions are identified, and compared with the National Climate Change Response Plan (NCCRP) lines of action.

A Simple Access Pricing Rule to Achieve the Ramsey Outcome in Two-Way Access

In this paper, I consider a general and informationally effcient approach to determine the optimal access rule and show that there exists a simple rule that achieves the Ramsey outcome as the unique equilibrium when networks compete in linear prices without network-based price discrimination. My approach is informationally effcient in the sense that the regulator is required to know only the marginal cost structure, i.e. the marginal cost of making and terminating a call. The approach is general in that access prices can depend not only on the marginal costs but also on the retail prices, which can be observed by consumers and therefore by the regulator as well. In particular, I consider the set of linear access pricing rules which includes any fixed access price, the Efficient Component Pricing Rule (ECPR) and the Modified ECPR as special cases. I show that in this set, there is a unique access rule that achieves the Ramsey outcome as the unique equilibrium as long as there exists at least a mild degree of substitutability among networks' services.

Downsizing, Job Insecurity, and Firm Reputation

This paper studies how firms make layoff decisions in the presence of adverse shocks. In this uncertain environment, workers' expectations about their job security affect their on-the-job performance. This productivity effect on job insecurity forces firms to strike a balance between laying off redundant workers and maintaining survivors' commitment when deciding on the amount and timing of downsizing. This framework offers an explanation of conservative employment practices (such as zero or reduced layoffs) based on firms having private information about their future profits. High retention rates and wages can signal that the firm has a bright future, boosting workers' confidence. Moreover, the model provides clear predictions about when waves of downsizing will occur as opposed to one-time massive cuts.

Mobile termination and mobile penetration

In this paper, we study how access pricing affects network competition when subscription demand is elastic and each network uses non-linear prices and can applytermination-based price discrimination. In the case of a fixed per minute terminationcharge, we find that a reduction of the termination charge below cost has two opposing effects: it softens competition but helps to internalize network externalities. Theformer reduces mobile penetration while the latter boosts it. We find that firms always prefer termination charge below cost for either motive while the regulator preferstermination below cost only when this boosts penetration.Next, we consider the retail benchmarking approach (Jeon and Hurkens, 2008)that determines termination charges as a function of retail prices and show that thisapproach allows the regulator to increase penetration without distorting call volumes.

A tractable consideration set structure for network revenue management

Models incorporating more realistic models of customer behavior, as customers choosing from an offerset, have recently become popular in assortment optimization and revenue management. The dynamicprogram for these models is intractable and approximated by a deterministic linear program called theCDLP which has an exponential number of columns. When there are products that are being consideredfor purchase by more than one customer segment, CDLP is difficult to solve since column generationis known to be NP-hard. However, recent research indicates that a formulation based on segments withcuts imposing consistency (SDCP+) is tractable and approximates the CDLP value very closely. In thispaper we investigate the structure of the consideration sets that make the two formulations exactly equal.We show that if the segment consideration sets follow a tree structure, CDLP = SDCP+. We give acounterexample to show that cycles can induce a gap between the CDLP and the SDCP+ relaxation.We derive two classes of valid inequalities called flow and synchronization inequalities to further improve(SDCP+), based on cycles in the consideration set structure. We give a numeric study showing theperformance of these cycle-based cuts.

A new compact linear programming formulation for choice network revenue management

The choice network revenue management model incorporates customer purchase behavioras a function of the offered products, and is the appropriate model for airline and hotel networkrevenue management, dynamic sales of bundles, and dynamic assortment optimization.The optimization problem is a stochastic dynamic program and is intractable. A certainty-equivalencerelaxation of the dynamic program, called the choice deterministic linear program(CDLP) is usually used to generate dyamic controls. Recently, a compact linear programmingformulation of this linear program was given for the multi-segment multinomial-logit (MNL)model of customer choice with non-overlapping consideration sets. Our objective is to obtaina tighter bound than this formulation while retaining the appealing properties of a compactlinear programming representation. To this end, it is natural to consider the affine relaxationof the dynamic program. We first show that the affine relaxation is NP-complete even for asingle-segment MNL model. Nevertheless, by analyzing the affine relaxation we derive a newcompact linear program that approximates the dynamic programming value function betterthan CDLP, provably between the CDLP value and the affine relaxation, and often comingclose to the latter in our numerical experiments. When the segment consideration sets overlap,we show that some strong equalities called product cuts developed for the CDLP remain validfor our new formulation. Finally we perform extensive numerical comparisons on the variousbounds to evaluate their performance.

Competitive location and pricing on networks

In this paper we consider a location and pricing model for a retail firm that wants to enter a spatial market where a competitor firm is already operating as a monopoly with several outlets. The entering firms seeks to determine the optimal uniform mill price and its servers' locations that maximizes profits given the reaction in price of the competitor firm to its entrance. A tabu search procedure is presentedto solve the model together with computational experience.

A simple access pricing rule to achieve the Ramsey outcome for interconnected networks

This paper considers a general and informationally efficient approach to determine the optimal access pricing rule for interconnected networks. It shows that there exists a simple rule that achieves the Ramsey outcome as the unique equilibrium when networks compete in linear prices without network-based price discrimination. The approach is informationally efficient in the sense that the regulator is required to know only the marginal cost structure, i.e. the marginal cost of making and terminating a call. The approach is general in that access prices can depend not only on the marginal costs but also on the retail prices, which can be observed by consumers and therefore by the regulator as well. In particular, I consider the set of linear access pricing rules which includes any fixed access price, the Efficient Component Pricing Rule (ECPR) and the Modified ECPR as special cases. I show that in this set, there is a unique rule that implements the Ramsey outcome as the unique equilibrium independently of the underlying demand conditions.

Entrepreneurial structure of the mercantile company in pre-industrial Catalonia

The mercantile company was the basic form of enterprise in pre-industrial Catalonia. The aim of this paper is to study the formation and development of the mercantile companies in Barcelona whose end was the wholesale and retail sale of textiles in the botigues de teles (textile retail shops) throughout the eighteenth century. These firms were officially registered before a notary and their deeds reveal how these establishments were administered and managed.The study covers a sample of 121 mercantile companies, and the articles and documentation that were put into effect by 32 notaries who were active in Barcelona in the 18th century have been consulted in their entirety. From an initial selection of documentation, a total of 228 deeds registering companies have been found, 107 of which (47%) relate to the creation of companies whose various activities were centred in taverns, textile manufacturing, braiding.... While the 121 companies, which make up our sample and which account for 53% of the deeds registered with the notaries mentioned above, focused exclusively on the management of textile retail shops located in the commercial heart of the city. Thus one point of interest that the documentation reveals is that the majority of the mercantile companies registered by Barcelona notaries throughout the 18th century were establishments which traded in textiles. The first part of the article focuses on the structural characteristics of these enterprises, the number and socio-professional status of the partners and the extent of each partner s involvement in the administration and management. The second part of the article examines the capital investment made by each partner, their rights and obligations agreed on, the sharing out of profits and possible losses and the duration of the companies. The final aim of the paper is to highlight the evolution of these companies through one specific case.