A reliability-based optimization (RBO) methodology was developed and applied to fiber-reinforced polymer (FRP) bridge decks. Commercially available software was used to optimize a FRP bridge deck panel by weight with structural reliability, stress, and deflection constraints. A methodology using optimization software, finite element analysis, and probabilistic analysis software was developed to examine the effects of load and resistance uncertainties in FRP bridge deck optimization. Eight modular deck designs were considered for use in the RBO methodology. Investigations into random variable sensitivities, design variable sensitivities, wheel positions, and buckling were conducted to minimize computational effort. Five models were eventually optimized with deterministic methods and the RBO methodology. Ply thicknesses were treated as design variables. Material parameters, design variables, and load were taken as random variables in the reliability calculations. A comparison of RBO designs was made with the best candidate chosen based on deck panel weight.

This thesis sets out to explain the relationship between fiscal spending and economic growth. The relationship is established using a panel vector autoregression model estimated by GMM, using GDP growth and government spending on a panel of 30 OECD countries. The model used is tested with slight variations in specification which are concluded to be important in the finalized results. By altering the specification used in the model this thesis produces relatively different sizes on the multiplier effect both in the short run and in the long run effect. The size of the multiplier effect produced by this thesis is varying between 0.437 on the low side and 2.224 on the high side depending on a few alterations in model specification. Similarly, the long run multiplier effect is measured as 1.873 on the low side and 8.263 on the high side. The mean duration of the multiplier effect is estimated to be approximately 3 years.

Whether we would like to model imports and exports, or forecast inflation, structural variation in an economy frequently causes problems. This thesis examines such variation in two dimensions: first, in a cross-section of individuals, and secondly, over time. A panel of manufacturing industries in several developed countries reveals that there is substantial variation across sectors, in the response of trade to changes in prices and incomes. Ignoring this heterogeneity can render conventional results biased and inconsistent, so a number of robust methods are used to obtain reliable estimates of long-run and short-run trade relationships. The findings point to common behaviour across sectors, which could be due to similarities in technology. The impact of structural breaks over time is examined in the second part of the thesis. Unpredictable shifts in deterministic terms such as the mean of a process are shown to generate significant forecast failure, and even the methods used to evaluated forecast accuracy are affected. Using the Kullback-Leibler discrepancy to measure the size of forecast errors, various robust mechanisms are discussed, that do not fail systematically after a break. Although they can provide a degree of insurance if a shift does occur, this comes at a cost if there is no change, and in the presence of measurement error they can exacerbate the uncertainty surrounding a forecast. An empirical illustration with a model of UK money demand provides some support for the automatic correction mechanisms, although there does seem to be a role for direct modeling of a break process.

Le nombre de sujets du panel détermine en grande partie le coût des études descriptives et hédoniques de l'analyse sensorielle. Une fois les risques α et β fixés, ce nombre peut théoriquement être calculé, dés lors que l'on connait la variabilité de la mesure due à l'hétérogénéité de la population visée et que l'on fixe la taille de la différence que l'on désire mettre en évidence. En général, l'ordre de grandeur du premier de ces paramètres est inconnu alors que celui du second est délicat à préciser pour l'expérimentateur. Ce travail propose une documentation systématique des valeurs prises dans la réalité par ces deux paramètres grâce à l'exploitation de deux bases de données, SensoBase et PrefBase, contenant respectivement un millier de jeux de données descriptives et quelques centaines de jeux de données hédoniques. Pratiquement, des recommandations pour la taille de panel sont établies sous forme d'abaques prenant en compte trois niveaux pour chacun des deux risques et des deux paramètres.D'autre part, ce travail étudie le nombre de sujets dans chacun des deux types de panel par une approche de ré-échantillonnage qui consiste à réduire progressivement le nombre de sujets tant que les résultats de l'analyse statistique demeurent stables. En moyenne, la taille des panels descriptifs pourrait être réduite d'un quart du nombre de sujets, mais cette moyenne cache une forte hétérogénéité selon le type de descripteurs considéré. La taille optimale des panels hédoniques serait elle très variable et cette variabilité est induite beaucoup plus par la nature et l'importance des différences entre les produits que par l'hétérogénéité des préférences individuelles. De plus, une même approche de ré-échantillonnage appliquée aux répétitions en tests descriptifs suggère que les répétitions ne sont plus nécessaires en phase de mesure, c'est-à-dire une fois le panel entraîné / The costs associated with sensory evaluation increase with the number of panelists to be enrolled. Classical power computation can be used to derive the minimal number of subjects of a sensory panel in order to control both type I (α risk) and type II (β risk) errors. However, this power computation requires estimates of the size of the product effect to be sought and of the residual variability of the ANOVA model used. Generally, both product effect size and residual variability are difficult to estimate a priori by the sensory analyst. This work offers estimations of these two parameters thanks to the analysis of hundreds descriptive andhedonic studies collected respectively in two databases, SensoBase and PrefBase. The meta-analysis of the data allowed to quantify these two parameters and made possible the calculation of the number of panelists. Hence, tables of panel sizes were proposed for 3 levels of respectively product effect size, residual variability and type I and II errors. Of course, this was done independently for descriptive and hedonic tests.Another approach based on resampling in numerous datasets was applied for both descriptive and hedonic studies. The method used to derive adequate panel size consisted in removing k subjects from the N of the original panel and then measuring the loss of information in product comparisons. For descriptive panels, panel size could be reduced by a quarter but this reduction strongly depends on the type of attributes. For hedonic panels, panel sizes varied extremely and depended mainly on the size of the liking differences between products to be compared. We expect that this difference is directly affected by the level of sensory complexity of the products. Finally, the resampling approach was applied to examine the need to replicate with trained sensory panels. Results suggested that replicates are no longer necessary at the testing phase, that is once the panel is trained

The studies of exchange rate theory in international finance are divided into several schools. Purchasing Power Parity (PPP) is one important hypothesis in both the Monetary Exchange Rate theory and the main theory in the Open Macroeconomics Model. Although many models are found upon the existence of PPP, but it still has not been proved empirically. That is why it¡¦s important to examine the existence of PPP. In the past, the statistic analyzing processes are all made directly under the models since all variables have been assumed stationary. However, regressing two non-stationary variables may result in Spurious Regression. The Unit Roots Test and Cointegration Test are developed in order to avoid the problem of spurious regression. Therefore, Unit Roots Test and Cointegration Test should be applied to the variables before estimating during regression analyses. Concerning the power deficiency of Unit Roots Test and Cointegration Test, many researches have adopted the combination time-series and cross-section Panel Data Model in order to improve the power and limitation of small samples. The Panel-Unit Root Test and Panel-Cointegration Test have therefore been developed to avoid Spurious Regression. However, Panel-Unit Root Test and Panel-Cointegration Test are applied with long time-series and large cross-section. Nevertheless, obtaining the data has always been the toughest difficulty during empirical researches, let alone the need for long period and large unit data. These Panel Data Models can only be applied to studies for long period, but not to the short periods. In order to avoid these problems; Binder, Hsiao and Pesaran (2004) have developed the Short Panel Vector Autoregressions (sPVAR) Model, a Panel Data Model developed with short time-series and large cross-section. Therefore, this paper will focus on Purchasing Power Parity under the sPVAR Model with the examination of PPP for the 30 countries since the introduction of Euro (1998 to 2004).

Precast, prestressed concrete panels (PCPs) and cast-in-place (CIP) concrete slabs are commonly used in Texas and elsewhere. Because PCPs are placed between bridge girders, and CIP concrete slabs are cast over the PCPs, PCPs act as formwork, cost and time for construction can be reduced. However, current designs may be further optimized if it can be shown that the reinforcement in the CIP deck can be reduced. Another issue involves cracking of PCP during fabrication and transportation to the site. The goal of this dissertation is to recommend changes to the CIP-PCP bridge decks that will lead to more cost-effective bridges. The first phase of the research is to suggest an optimized reinforcement layout for cast-in-place (CIP) slabs. Because the capacity of these decks is much greater than the design loads, a decrease in top-mat reinforcement will have minimal effect on the margin of capacity over design loads. Two options were selected, reduced deformed-bar reinforcement; and reduced welded-wire reinforcement. These two options are evaluated through restrained-shrinkage tests and field applications. The second phase of this dissertation is to reduce cracks in precast, prestressed concrete panels (PCPs) which occur during fabrication, handling, and transportation. Most cracks in PCPs are collinear (occur along the strands). They can be reduced in two ways. The first is to reduce initial prestress. The second is to place additional transverse reinforcement at edges. / text

An ergonomic control panel was designed for a remotely operated agricultural tractor. In order to inform the design, information was collected via ergonomic literature, ride-alongs with tractor operators, and interviews with tractor operators and experienced design professionals. Ride-alongs were used to determine frequency and sequence of use in agricultural tractors. The most frequently used control was the one that controlled the implement being pulled behind the tractor. There was no sequence pattern observed over all the ride-alongs. The control panel design was evaluated using design criteria from the information collected, the Index of Functionality, and the Index of Accessibility. The Index of Functionality was assessed and validated as a tool for ergonomic control panel design. The final design satisfied all the criteria outlined and achieved good index scores.

An ergonomic control panel was designed for a remotely operated agricultural tractor. In order to inform the design, information was collected via ergonomic literature, ride-alongs with tractor operators, and interviews with tractor operators and experienced design professionals. Ride-alongs were used to determine frequency and sequence of use in agricultural tractors. The most frequently used control was the one that controlled the implement being pulled behind the tractor. There was no sequence pattern observed over all the ride-alongs. The control panel design was evaluated using design criteria from the information collected, the Index of Functionality, and the Index of Accessibility. The Index of Functionality was assessed and validated as a tool for ergonomic control panel design. The final design satisfied all the criteria outlined and achieved good index scores.

Zugl.: Münster (Westfalen), Universiẗat, Diss., 2008.

Konstanz, Univ., Diplomarb., 2007.