Large software projects are characterized by distributed environments consisting of teams at different organizations and geographical locations. These teams typically build multiple overlapping models, representing different perspectives, different versions across time, different variants in a product family, different development concerns, etc. Keeping track of the relationships between these models, constructing a global view, and managing consistency are major challenges. Model Management is concerned with describing the relationships between distributed models, i.e., models built in a distributed development environment, and providing systematic operators to manipulate these models and their relationships. Such operators include, among others, Match, for finding relationships between disparate models, Merge, for combining models with respect to known or hypothesized relationships between them, Slice, for producing projections of models and relationships based on given criteria, and Check-Consistency, for verifying models and relationships against the consistency properties of interest. In this thesis, we provide automated solutions for two key model management operators, Merge and Check-Consistency. The most novel aspects of our work on model merging are (1) the ability to combine arbitrarily large collections of interrelated models and (2) support for toleration of incompleteness and inconsistency. Our consistency checking technique employs model merging to reduce the problem of checking inter-model consistency to checking intra-model consistency of a merged model. This enables a flexible way of verifying global consistency properties that is not possible with other existing approaches. We develop a prototype tool, TReMer+, implementing our merge and consistency checking approaches. We use TReMer+ to demonstrate that our contributions facilitate understanding and refinement of the relationships between distributed models.

The aim of this thesis is to develop faster method for stable model computation of non-stratified logic programs and study its efficiency. It focuses mainly on the stable model and weak well founded semantics of logic programs. We propose an approach to compute stable models by where we first transform the logic program using paraconsistent relational model, then we compute the weak-well founded model which is used to generate a set of models consisting of the true and unknown values, which are tested for stability. We perform some experiments to test the efficiency of our approach which incurs overhead to eliminate negative values against a Naïve method of stable model computation.

The energy requirements of forage harvesters can be quite high and can sometimes determine the size of tractor needed on a farm. Therefore, improving the energy efficiency of the forage harvester could allow a farm to reduce costs by using a smaller tractor that is less expensive and more efficient. The objective of this research was to increase the throwing distance of a forage harvester by modeling the flow of forage in the spout and the air flow in the blower and spout. These models can then be used to compare the efficiencies of prototype designs. The air flow in the blower and spout was modeled using the commercial computational fluid dynamics software FLUENT. The simulation results of air velocities and flow patterns were compared to experimental values and it was found that both were of the same order of magnitude with the model predicting slightly higher air velocities than those measured. The flow of forage in the spout was modeled analytically by taking into account the friction between the forage and the spout surface and the aerodynamic resistance after the forage leaves the spout. From this model, two improved prototype spouts that should theoretically result in longer throwing distances were designed. However, field testing of the two prototypes did not reveal any significant improvements over the current design. It was also found that the model under-predicted the throwing distance of one prototype by 2 % and over estimated the other by 12 %.

Large software projects are characterized by distributed environments consisting of teams at different organizations and geographical locations. These teams typically build multiple overlapping models, representing different perspectives, different versions across time, different variants in a product family, different development concerns, etc. Keeping track of the relationships between these models, constructing a global view, and managing consistency are major challenges. Model Management is concerned with describing the relationships between distributed models, i.e., models built in a distributed development environment, and providing systematic operators to manipulate these models and their relationships. Such operators include, among others, Match, for finding relationships between disparate models, Merge, for combining models with respect to known or hypothesized relationships between them, Slice, for producing projections of models and relationships based on given criteria, and Check-Consistency, for verifying models and relationships against the consistency properties of interest. In this thesis, we provide automated solutions for two key model management operators, Merge and Check-Consistency. The most novel aspects of our work on model merging are (1) the ability to combine arbitrarily large collections of interrelated models and (2) support for toleration of incompleteness and inconsistency. Our consistency checking technique employs model merging to reduce the problem of checking inter-model consistency to checking intra-model consistency of a merged model. This enables a flexible way of verifying global consistency properties that is not possible with other existing approaches. We develop a prototype tool, TReMer+, implementing our merge and consistency checking approaches. We use TReMer+ to demonstrate that our contributions facilitate understanding and refinement of the relationships between distributed models.

A new three-dimensional finite solid element (3D FE) model for dowel-type wood connections was developed using the concept of a beam on a nonlinear wood foundation, which addresses the intricate wood crushing behaviour under the connector in a dowel type connection. In order to implement the concept of wood foundation with solid elements, a 3D FE wood foundation model was defined within a prescribed foundation zone surrounding the dowel. Based on anisotropic plasticity material theory, the material model for the foundation zone was developed using effective foundation material constants that were defined from dowel-embedment test data. New 3D FE single nail connection models were developed that incorporated the wood foundation model. The 3D wood foundation model was justified and validated using dowel-embedment test data with a range of dowel diameters, from a 2.5-mm nail to a25.4-mm bolt. The connection models provided successful results in simulating the characteristics of load-slip behaviour that were experimentally observed. Based on the success of the single nail connection models, several applications of the3D FE connection models were investigated including statistical wood material models, bolted connection models and a multiple nail connection model. Throughout the application studies, discussion of the benefits and limitations of the new model approach using the 3D FE wood foundation are presented. Also, future areas of study are proposed in order to improve the 3D FE dowel-type wood connections models.

New possibilities are developing in the infrastructure of electrical systems to meet the new demand of more volatile power generation. This study focuses on German household reactions to price changes and their economic and renewable utilization effects.   In order to model the effects of flexible prices in the Freiamt region, the basic research – including interviews and data collecting – is carried out in the fields of economics and renewable energy. An elasticity model based on the Spees and Lave study in used to simulate consumer behaviour to changing prices.   Two pricing structures with daily and hourly changing prices are found to lower the average electrical prices in both cases. These benefits are larger overall with the hourly price changes when all other variables are kept constant. This study finds that the changes to load patterns also seem to correlate with the local renewable energy production. Results suggest that this specific form of energy generation benefits from consumer reactions to changing prices during 2007 and 2008.   In order to validate these results the model should be expanded to include a more differentiated load from different sectors and to include a wider range of the electrical prices advertised to the consumer. However, under given circumstances, this study concludes that using more renewable power generation is possible both generally with daily price changes and also more specifically with hourly changing prices at a more competitive market price.

The energy requirements of forage harvesters can be quite high and can sometimes determine the size of tractor needed on a farm. Therefore, improving the energy efficiency of the forage harvester could allow a farm to reduce costs by using a smaller tractor that is less expensive and more efficient. The objective of this research was to increase the throwing distance of a forage harvester by modeling the flow of forage in the spout and the air flow in the blower and spout. These models can then be used to compare the efficiencies of prototype designs. The air flow in the blower and spout was modeled using the commercial computational fluid dynamics software FLUENT. The simulation results of air velocities and flow patterns were compared to experimental values and it was found that both were of the same order of magnitude with the model predicting slightly higher air velocities than those measured. The flow of forage in the spout was modeled analytically by taking into account the friction between the forage and the spout surface and the aerodynamic resistance after the forage leaves the spout. From this model, two improved prototype spouts that should theoretically result in longer throwing distances were designed. However, field testing of the two prototypes did not reveal any significant improvements over the current design. It was also found that the model under-predicted the throwing distance of one prototype by 2 % and over estimated the other by 12 %.

The implication of credit rationing models states that the effect of monetary policy on output may be stronger when credit conditions are tight than when they are loose. Therefore, there may be a thresholde effect on the relation between real money supply and output. Existing empirical studies on testing threshold effects ignore the fact that the monetary policy and the credit conditions are endogenous, which are follow some optimal rules. Seeing that the past studies considering the endogenous monetary policy only cannot provide substantial evidence of the credit rationing theory, this article provides an extending test of threshold effects when monetary policy and the indicator of credit conditions are endogenous. Moreover, this study finds that the US aggregate data can still provide significant evidence of a threshold effect on the relation between money and output, comparing to the endogenous monetary policy partially considered.

This study examines the effects that individual personality traits have on technology acceptance. Previous research on technology acceptance focuses primarily on exogenous variables such as trustor’s perceptions, attitudes, computer anxiety, positive or negative affect, age, and experience. This research seeks to improve our understanding of technology acceptance by examining user interpersonal traits as the underpinnings of user perceptions of technology and disposition to trust. A general theory of personality, the interpersonal circumplex (IPC) model, is used here as a framework to explain IT-users’ computer self-efficacy, computer anxiety, and perceptions about- and trust in technology. The interpersonal circumplex model is well established and provides a strong foundation for understanding interaction styles and interpersonal trust. Based on the interpersonal circumplex model, I develop predictions about how various personality types will interact with technology acceptance model (TAM) related variables: that is, I predict how individuals with different interpersonal traits will rate the following: their computer selfefficacy, computer anxiety, and perceptions of an information system’s performance; the system’s trustworthiness, ease of use, usefulness; as well as the user’s behavioral intention to use the system in the future. In general, I hypothesize that a computer user’s blend of the primary interpersonal dimensions of Control and Affiliation influences his or her responses to computer usage related questions. In this study, student-participants completed an on-line assessment of their interpersonal dispositions, using the Circumplex Scales of Interpersonal Values (CSIV; Locke, 2000); subsequently the studentparticipants reported their perceptions of- and trust in a computer-based learning system that they used as part of their class. In particular, this research suggests that the Communality (Affiliation) dimension of personality, as measured by the CSIV, indicates particular and significant correlations to user’s computer anxiety, perceived system performance, perceived usefulness (of the technology), and behavioral intent to use (IT) in the future. The Interpersonal Circumplex demonstrates improved acuity in detecting personality differences that may impact the way users respond to, perceive, and evaluate technology. As a new tool for information systems research, the IPC shows potential to provide further insight into IS theory by building a bridge between interpersonal theory and technology acceptance models.

Credit risk of derivative securities includes the risk of underlying company and the risk of seller's nonfulfilment of contracts. Take bonds for example, we regard Treasury bills as default-free bonds, and corporate bonds as risky bonds. When the liability of property of derivative securities underlying company is less than 1, we regard the company is of bankruptcy. And then the seller of derivative securities will break the contract. The essay extends two period risky bonds pricing valuation of Jarrow and Turnbull(1995) to multiperiod situation, and derive arbitrage-free condition. Furthermore, we derive formulae of risky bonds prices by assuming the logarithm of the odds ratio of an underlying company's bankruptcy probability satisfies an AR(1) or MA(1) processes. Empirical data of Rebar, Chinarebar, Ceon are studied, time series models are established for logarithm of odds ratios. In most cases, we find that the log odds ratios can be well fitted by AR(1) models.