The main goal of any object-oriented analysis (OOA) method is to produce a model that aids in understanding and communicating knowledge about a modeled domain. A higher degree of similarity among independently produced domain models provides an indication of how well the domain was understood by the different analysts, i. e. , more similar models indicate a closer and a more common understanding of a domain. A common understanding is of critical importance for effective knowledge communication and sharing. <br /><br /> The core of any OOA method is discovering and understanding concepts and their relationships in a domain. The main artifact produced by an OOA method is a domain model of the domain. A domain model often serves as the main source of design concepts during objectoriented design (OOD). This thesis evaluates two OOA methods by comparing the degree of similarity of the resulting domain models. <br /><br /> In particular, this work compares the semantic similarity of domain models extracted from use cases by <ol> <li>specification of sequence diagrams and then domain models, and </li> <li>specification of unified use case statecharts and then domain models. </li> </ol> The thesis makes case studies out of the application of the first method to 31 instances of large Voice-over-IP (VoIP) system and its information management system (IMS) and to 3 small elevator systems, and out of the application of the second method to 46 instances of the same large VoIP system and its IMS and to 12 instances of a medium-sized elevator system. <br /><br /> From an analysis of data from these case studies, the thesis concludes that there is an increase of 10% in the semantic similarity of domain models produced using the second method, but at the cost of less than or equal to 25% more analysis time.

The main goal of any object-oriented analysis (OOA) method is to produce a model that aids in understanding and communicating knowledge about a modeled domain. A higher degree of similarity among independently produced domain models provides an indication of how well the domain was understood by the different analysts, i. e. , more similar models indicate a closer and a more common understanding of a domain. A common understanding is of critical importance for effective knowledge communication and sharing. <br /><br /> The core of any OOA method is discovering and understanding concepts and their relationships in a domain. The main artifact produced by an OOA method is a domain model of the domain. A domain model often serves as the main source of design concepts during objectoriented design (OOD). This thesis evaluates two OOA methods by comparing the degree of similarity of the resulting domain models. <br /><br /> In particular, this work compares the semantic similarity of domain models extracted from use cases by <ol> <li>specification of sequence diagrams and then domain models, and </li> <li>specification of unified use case statecharts and then domain models. </li> </ol> The thesis makes case studies out of the application of the first method to 31 instances of large Voice-over-IP (VoIP) system and its information management system (IMS) and to 3 small elevator systems, and out of the application of the second method to 46 instances of the same large VoIP system and its IMS and to 12 instances of a medium-sized elevator system. <br /><br /> From an analysis of data from these case studies, the thesis concludes that there is an increase of 10% in the semantic similarity of domain models produced using the second method, but at the cost of less than or equal to 25% more analysis time.

Computational Fluid Dynamics (CFD) applications usually involve intensive computations, which can be accelerated through using open accelerators, especially GPUs due to their common use in the scientific computing community. In addition to code acceleration, it is important to ensure that the code and algorithm are implemented numerically correctly, which is called code verification. This dissertation focuses on accelerating research CFD codes on multi-CPUs/GPUs using MPI and OpenACC, as well as the code verification for turbulence model implementation using the method of manufactured solutions and code-to-code comparisons. First, a variety of performance optimizations both agnostic and specific to applications and platforms are developed in order to 1) improve the heterogeneous CPU/GPU compute utilization; 2) improve the memory bandwidth to the main memory; 3) reduce communication overhead between the CPU host and the GPU accelerator; and 4) reduce the tedious manual tuning work for GPU scheduling. Both finite difference and finite volume CFD codes and multiple platforms with different architectures are utilized to evaluate the performance optimizations used. A maximum speedup of over 70 is achieved on 16 V100 GPUs over 16 Xeon E5-2680v4 CPUs for multi-block test cases. In addition, systematic studies of code verification are performed for a second-order accurate finite volume research CFD code. Cross-term sinusoidal manufactured solutions are applied to verify the Spalart-Allmaras and k-omega SST model implementation, both in 2D and 3D. This dissertation shows that the spatial and temporal schemes are implemented numerically correctly. / Doctor of Philosophy / Computational Fluid Dynamics (CFD) is a numerical method to solve fluid problems, which usually requires a large amount of computations. A large CFD problem can be decomposed into smaller sub-problems which are stored in discrete memory locations and accelerated by a large number of compute units. In addition to code acceleration, it is important to ensure that the code and algorithm are implemented correctly, which is called code verification. This dissertation focuses on the CFD code acceleration as well as the code verification for turbulence model implementation. In this dissertation, multiple Graphic Processing Units (GPUs) are utilized to accelerate two CFD codes, considering that the GPU has high computational power and high memory bandwidth. A variety of optimizations are developed and applied to improve the performance of CFD codes on different parallel computing systems. The program execution time can be reduced significantly especially when multiple GPUs are used. In addition, code-to-code comparisons with some NASA CFD codes and the method of manufactured solutions are utilized to verify the correctness of a research CFD code.

Baigiamajame magistro darbe analizuojami rolinio modeliavimo aspektai įvairių programų sistemų kūrimo metodų ir procesų rėžiuose. Modeliavimo aspektai analizuojami objektinio programavimo evoliucijos kontekste. Apžvelgiamos įvairios prielaidos leidžiančios visuose programų sistemų kūrimo etapuose atskirti sistemos elgseną ir išreikštinai sistemą modeliuoti rolėmis. Darbe identifikuojamos programų sistemų kūrimo procesų dalys, kurios stokoja rolinio modeliavimo instrumentų. Pasiūlomi programų sistemų konstravimo etapo problemų susijusių su elgsenos modeliavimu klasikiniame objektiniame programavime sprendimo būdai. Taip pat pateikiamos programų sistemų kūrimo proceso modifikavimo rekomendacijos dėl rolinio modeliavimo panaudojimo visuose sistemos kūrimo etapuose. / Final master thesis comprises role modeling aspects in various software development processes and methods. The analysis is made in the context of object-oriented programming evolution. The survey is made on miscellaneous assumptions related to explicit role modeling and separation of system state and behaviour concerns in software development. The parts of software development process which have a lack of role modeling techniques are identified in this thesis. The suggestions of solutions to classic object-oriented programming behaviour modeling problems for software construction phase are made. Finally, the recommendations related to role modeling for software development process modification are made to support all the development phases.

Even though there are many software development and project management methodologies available, research and practice both show that IT software development projects still fail, and that the quality of software products does not always meet customers' expectations. There might be multiple causes for such failures, but some of these reasons can be seen to influence or create others. Therefore, the larger the project is, the higher its risk of failure, especially if the teams involved work remotely (distributed and outsourced). This increase in project complexity is considered the motivation for this paper. Similarly, there are other factors that can result in a project's failure and customers' dissatisfaction regarding software quality. All such factors identified by research conducted by organizations specializing in this area are analyzed in order to identify a common root of IT project failures. Once the root causes of these failures have been identified and analyzed, the goal of the Interface based software development methodology is to solve them. The solution offered by an Interface based software development methodology is to improve understanding of software requirements and to describe these requirements with interfaces in an object-oriented way. Interface based software development will support and drive development towards service-oriented architecture (SOA) and component-based development (CBD). The goal of interface based software development is to increase software testability and maintainability and to make it more easily feasible to execute various software development processes in parallel.

Die Arbeit untersucht die Realisierungsmöglichkeiten der Potenziale des objektorientierten Paradigmas im Bereich der Management Support Systems (MSS). Die Untersuchung konzentriert sich dabei auf die grundlegende Datenhaltungskomponente, das Data Warehouse (DWH) respektive Object Warehouse. Dazu wird im ersten Teil zunächst nach einer ausführlichen Analyse der Begriffslandschaft im Bereich der Management Support Systems und einer geeigneten Neudefinition und Einordnung des Data Warehouse auf den Entwicklungspfad des Data Warehouse eingegangen, bei welchem insbesondere die Anforderungen und Zielsetzungen des Data-Warehouse-Konzeptes herausgearbeitet werden. Darauf aufbauend wird ein generelles, systemunabhängiges Data-Warehouse-Konzept entwickelt und gegenüber den in der Literatur und Praxis vorherrschenden, konventionellen Konzepten bewertet. Basierend auf einer umfassenden Klassifizierung und Analyse des objektorientierten Paradigmas und seiner MSS- und DWH-spezifischen Verbesserungspotenziale erfolgt anschließend die Konzeption für ein Object Warehouse. Angesichts der erheblichen Anzahl bezüglich Konzepten und Zielsetzungen sehr unterschiedlicher Objekt-Paradigmata, muss die gleichwohl notwendige Paradigmen-Diskussion und Integration teilweise beschränkt auf den Teilaspekt der Objectbase Management Systems (OBMS) erfolgen, speziell auf solche, die die geforderten semantischen Modellierungsmöglichkeiten des Objekt-Paradigmas für den Reconciled Object Layer des Data Warehouse unterstützen. Im zweiten Teil der Arbeit werden die in konkreten Projekten gewonnenen Erkenntnisse bezüglich der Umsetzung des Object-Warehouse-Konzeptes in der Praxis vorgestellt und einer kritischen Würdigung unterzogen. Dabei werden erhebliche Diskrepanzen bezüglich der Umsetzung methodischer Konzeptionen in realen Software-Werkzeugen expliziert, was eine umfassende Umsetzung des Object-Warehouse-Konzeptes zur Zeit noch erheblich einschränkt.