The efficiency of direct payments versus tax reductions under uncertainty

This paper analyzes the optimal behavior of farmers in the presence of direct payments and uncertainty. In an empirical analysis for Switzerland, it confirms previously obtained theoretical results and determines the magnitude of the theoretical predicted effects. The results show that direct payments increase agricultural production between 3.7% to 4.8%. Alternatively to direct payments, the production effect of tax reductions is evaluated in order to determine its magnitude. The empirical analysis corroborates the theoretical results of the literature and demonstrates that tax reductions are also distorting, but to a substantially lesser degree if losses are not offset. However, tax reductions, independently whether losses are offset or not, lead to higher government spending than pure direct payments

Desenvolupament d’una metodologia de simulació mitjançant programari CFD per a la optimització d’agitadors

La dinàmica de fluids computacional (CFD) és una eina que serveix per analitzar mitjançant computadors diferents problemes que involucren fluxos de fluids. Els programes de CFD usen expressions matemàtiques no lineals que defineixen les equacions fonamentals de fluxos i transport de calor en fluids. Aquestes es resolen amb complexos algoritmes iteratius. Actualment aquesta eina és una part fonamental en els procés de disseny en moltes empreses relacionades amb la dinàmica de fluids. Les simulacions que es realitzen amb aquests programes s’ha demostrat que són fiables i que estalvien temps i diners, ja que eviten haver de realitzar els costosos processos d’assaig-error. En el projecte s’utilitza el programa de CFD Ansys CFX 11.0 per simular una agitació bifàsica composta per aigua i aire a temperatura ambient. Els objectius són determinar els paràmetres òptims de simulació que permetin recrear aquesta agitació, per posteriorment dissenyar un nou impulsor

Estudi i simulació aerodinàmica amb programari de dinàmica de fluids computacional (CFD) en un model bàsic de vehicle de competició de la categoria CM (curses de muntanya)

Aquest projecte té com a objectiu la simulació numérica de la carrosseria d’ un vehicle de curses de muntanya de categoria CM

Robust fault detection using consistency techniques for uncertainty handling

Often practical performance of analytical redundancy for fault detection and diagnosis is decreased by uncertainties prevailing not only in the system model, but also in the measurements. In this paper, the problem of fault detection is stated as a constraint satisfaction problem over continuous domains with a big number of variables and constraints. This problem can be solved using modal interval analysis and consistency techniques. Consistency techniques are then shown to be particularly efficient to check the consistency of the analytical redundancy relations (ARRs), dealing with uncertain measurements and parameters. Through the work presented in this paper, it can be observed that consistency techniques can be used to increase the performance of a robust fault detection tool, which is based on interval arithmetic. The proposed method is illustrated using a nonlinear dynamic model of a hydraulic system

Fault diagnosis by refining the parameter uncertainty space of nonlinear dynamic systems

This paper deals with fault detection and isolation problems for nonlinear dynamic systems. Both problems are stated as constraint satisfaction problems (CSP) and solved using consistency techniques. The main contribution is the isolation method based on consistency techniques and uncertainty space refining of interval parameters. The major advantage of this method is that the isolation speed is fast even taking into account uncertainty in parameters, measurements, and model errors. Interval calculations bring independence from the assumption of monotony considered by several approaches for fault isolation which are based on observers. An application to a well known alcoholic fermentation process model is presented

Simulació mitjançant tècniques CFD d'una culata per al motor del vehicle de baix consum "Àliga-EPS-UdG"

El projecte pretén estudiar i quantificar les restriccions creades al fluid en circular pels conductes d’admissió i escapament de la culata del motor del vehicle Àliga. L’estudi consta de quatre etapes: estudi de les restriccions actuals dels sistemes d’admissió i escapament; anàlisi dels resultats de la culata de sèrie i proposta de millores aplicables al model real; càlcul de les restriccions creades pels models millorats, i finalment, estudi comparatiu dels resultats obtinguts, interpretant els resultats dels principals paràmetres a analitzar

Prediction of postprandial blood glucose under intra-patient variability and uncertainty and its use in the design of insulin dosing strategies for type 1 diabetic patients

In this thesis I propose a novel method to estimate the dose and injection-to-meal time for low-risk intensive insulin therapy. This dosage-aid system uses an optimization algorithm to determine the insulin dose and injection-to-meal time that minimizes the risk of postprandial hyper- and hypoglycaemia in type 1 diabetic patients. To this end, the algorithm applies a methodology that quantifies the risk of experiencing different grades of hypo- or hyperglycaemia in the postprandial state induced by insulin therapy according to an individual patient’s parameters. This methodology is based on modal interval analysis (MIA). Applying MIA, the postprandial glucose level is predicted with consideration of intra-patient variability and other sources of uncertainty. A worst-case approach is then used to calculate the risk index. In this way, a safer prediction of possible hyper- and hypoglycaemic episodes induced by the insulin therapy tested can be calculated in terms of these uncertainties.