A framework for transforming, analyzing, and realizing software designs in unified modeling language

Unified Modeling Language (UML) is the most comprehensive and widely accepted object-oriented modeling language due to its multi-paradigm modeling capabilities and easy to use graphical notations, with strong international organizational support and industrial production quality tool support. However, there is a lack of precise definition of the semantics of individual UML notations as well as the relationships among multiple UML models, which often introduces incomplete and inconsistent problems for software designs in UML, especially for complex systems. Furthermore, there is a lack of methodologies to ensure a correct implementation from a given UML design. The purpose of this investigation is to verify and validate software designs in UML, and to provide dependability assurance for the realization of a UML design.^ In my research, an approach is proposed to transform UML diagrams into a semantic domain, which is a formal component-based framework. The framework I proposed consists of components and interactions through message passing, which are modeled by two-layer algebraic high-level nets and transformation rules respectively. In the transformation approach, class diagrams, state machine diagrams and activity diagrams are transformed into component models, and transformation rules are extracted from interaction diagrams. By applying transformation rules to component models, a (sub)system model of one or more scenarios can be constructed. Various techniques such as model checking, Petri net analysis techniques can be adopted to check if UML designs are complete or consistent. A new component called property parser was developed and merged into the tool SAM Parser, which realize (sub)system models automatically. The property parser generates and weaves runtime monitoring code into system implementations automatically for dependability assurance. The framework in the investigation is creative and flexible since it not only can be explored to verify and validate UML designs, but also provides an approach to build models for various scenarios. As a result of my research, several kinds of previous ignored behavioral inconsistencies can be detected.^

Essays on international lending and increasing returns to scale

Standard economic theory suggests that capital should flow from rich countries to poor countries. However, capital has predominantly flowed to rich countries. The three essays in this dissertation attempt to explain this phenomenon. The first two essays suggest theoretical explanations for why capital has not flowed to the poor countries. The third essay empirically tests the theoretical explanations.^ The first essay examines the effects of increasing returns to scale on international lending and borrowing with moral hazard. Introducing increasing returns in a two-country general equilibrium model yields possible multiple equilibria and helps explain the possibility of capital flows from a poor to a rich country. I find that a borrowing country may need to borrow sufficient amounts internationally to reach a minimum investment threshold in order to invest domestically.^ The second essay examines how a poor country may invest in sectors with low productivity because of sovereign risk, and how collateral differences across sectors may exacerbate the problem. I model sovereign borrowing with a two-sector economy: one sector with increasing returns to scale (IRS) and one sector with diminishing returns to scale (DRS). Countries with incomes below a threshold will only invest in the DRS sector, and countries with incomes above a threshold will invest mostly in the IRS sector. The results help explain the existence of a bimodal world income distribution.^ The third essay empirically tests the explanations for why capital has not flowed from the rich to the poor countries, with a focus on institutions and initial capital. I find that institutional variables are a very important factor, but in contrast to other studies, I show that institutions do not account for the Lucas Paradox. Evidence of increasing returns still exists, even when controlling for institutions and other variables. In addition, I find that the determinants of capital flows may depend on whether a country is rich or poor.^

Toward a unified theory of task -oriented and relationship -oriented leader behavior: A multi -country generalizability study

The theoretical foundation of this study comes from the significant recurrence throughout the leadership literature of two distinct behaviors, task orientation and relationship orientation. Task orientation and relationship orientation are assumed to be generic behaviors, which are universally observed and applied in organizations, even though they may be uniquely enacted in organizations across cultures. The lack of empirical evidence supporting these assumptions provided the impetus to hypothetically develop and empirically confirm the universal application of task orientation and relationship orientation and the generalizability of their measurement in a cross-cultural setting. Task orientation and relationship orientation are operationalized through consideration and initiation of structure, two well-established theoretical leadership constructs. Multiple-group mean and covariance structures (MACS) analyses are used to simultaneously validate the generalizability of the two hypothesized constructs across the 12 cultural groups and to assess whether the similarities and differences discovered are measurement and scaling artifacts or reflect true cross-cultural differences. The data were collected by the author and others as part of a larger international research project. The data are comprised of 2341 managers from 12 countries/regions. The results provide compelling evidence that task orientation and relationship orientation, reliably and validly operationalized through consideration and initiation of structure, are generalizable across the countries/regions sampled. But the results also reveal significant differences in the perception of these behaviors, suggesting that some aspects of task orientation and relationship orientation are strongly affected by cultural influences. These (similarities and) differences reflect directly interpretable, error-free effects among the constructs at the behavioral level. Thus, task orientation and relationship orientation can demonstrate different relations among cultures, yet still be defined equivalently across the 11 cultures studied. The differences found in this study are true differences and may contain information about cultural influences characterizing each cultural context (i.e. group). The nature of such influences should be examined before the results can be meaningfully interpreted. To examine the effects of cultural characteristics on the constructs, additional hypotheses on the constructs' latent parameters can be tested across groups. Construct-level tests are illustrated in hypothetical examples in light of the study's results. The study contributes significantly to the theoretical understanding of the nature and generalizability of psychological constructs. The theoretical and practical implications of embedding context into a unified theory of task orientated and relationship oriented leader behavior are proposed. Limitations and contributions are also discussed. ^