Filters
Availability
Publication Year
Resource Type
Faculty
School/Institute
Publication Search Results
Sort
Results per page
1 - 10 of 29
-
-
-
-
-
-
-
(2006)ThesisEmbedded systems are becoming ubiquitous, primarily due to the fast evolution of digital electronic devices. The design of modern embedded systems requires systems to exhibit, high performance and reliability, yet have short design time and low cost. Application Specific Instruction set processors (ASIPs) are widely used in embedded system since they are economical to use, flexible, and reusable (thus saves design time). During the last decade research work on ASIPs have been carried out in mainly for single pipelined processors. Improving performance in processors is possible by exploring the available parallelism in the program. Designing of multiple parallel execution paths for parallel execution of the processor naturally incurs additional cost. The methodology presented in this dissertation has addressed the problem of improving performance in ASIPs, at minimal additional cost. The devised methodology explores the available parallelism of an application to generate a multi-pipeline heterogeneous ASIP. The processor design is application specific. No pre-defined IPs are used in the design. The generated processor contains multiple standalone pipelined data paths, which are not necessarily identical, and are connected by the necessary bypass paths and control signals. Control unit are separate for each pipeline (though with the same clock) resulting in a simple and cost effective design. By using separate instruction and data memories (Harvard architecture) and by allowing memory access by two separate pipes, the complexity of the controller and buses are reduced. The impact of higher memory latencies is nullified by utilizing parallel pipes during memory access. Efficient bypass network selection and encoding techniques provide a better implementation. The initial design approach with only two pipelines without bypass paths show speed improvements of up to 36% and switching activity reductions of up to 11%. The additional area costs around 16%. An improved design with different number of pipelines (more than two) based on applications show on average of 77% performance improvement with overheads of: 49% on area; 51% on leakage power; 17% on switching activity; and 69% on code size. The design was further trimmed, with bypass path selection and encoding techniques, which show a saving of up to 32% of area and 34% of leakage power with 6% performance improvement and 69% of code size reduction compared to the design approach without these techniques in the multi pipeline design.
-
(2006)ThesisStrategic alignment of IT exists when a business organization's goals and processes are in harmony with the IT software and systems that support them. Evidence shows that effective strategic alignment leads to superior financial performance of companies. Hence, CIOs and IT executives consistently rank alignment of IT with business strategy as a top priority in numerous surveys. Despite its importance to industry, strategic alignment has largely been ignored by requirements engineering research. The objective of the research presented in this thesis is to develop and test B-SCP, a requirements engineering analytical framework to help ensure that system requirements of organizational IT are in alignment with and provide support for competitive business strategy. B-SCP combines requirements engineering methods for formalizing and reasoning about software with analytical frameworks for competitive business strategy. Goal modeling, problem diagrams, and business process modeling, techniques typically used in isolation in requirements engineering, are integrated in a coherent framework. VMOST analysis, a management tool for organizational alignment, is used to elicit business strategy from executives. The Business Rules Group's Model for Organizational Motivation is used to provide guidance for constructing a goal model to represent business strategy. A business modeling framework proposed in management research on e-business systems, is used to define the boundaries of scope for the organizational IT requirements problem. B-SCP is evaluated and validated by two worked examples using data on completed, strategic IT projects of significant scale and complexity, occurring in different industrial application domains. The second worked example includes evaluation based on expert feedback from a major, IT executive stakeholder in the original project. This research concludes that B-SCP provides a credible solution to the industrial problem of validating organizational IT requirements against business strategy. This thesis makes a significant contribution to the field of requirements engineering research, in which issues of business strategy and strategic alignment have gone unaddressed. In addition, this thesis presents a potentially practical, real-world solution to the major, ongoing challenge of business- IT strategic alignment.
-
(2006)ThesisWeb portals are one of the rapidly growing applications, providing a single interface to access different sources (providers). The results from the providers are typically obtained by each provider querying a database and returning an HTML or XML document. Performance and in particular providing fast response time is one of the critical issues in such applications. Dissatisfaction of users dramatically increases with increasing response time, resulting in abandonment of Web sites, which in turn could result in loss of revenue by the providers and the portal. Caching is one of the key techniques that address the performance of such applications. In this work we focus on improving the performance of portal applications via caching. We discuss the limitations of existing caching solutions in such applications and introduce a caching strategy based on collaboration between the portal and its providers. Providers trace their logs, extract information to identify good candidates for caching and notify the portal. Caching at the portal is decided based on scores calculated by providers and associated with objects. We evaluate the performance of the collaborative caching strategy using simulation data. We show how providers can trace their logs and calculate cache-worthiness scores for their objects and notify the portal. We also address the issue of heterogeneous scoring policies by different providers and introduce mechanisms to regulate caching scores. We also show how portal and providers can synchronize their meta-data in order to minimize the overhead associated with collaboration for caching.
-
(2006)ThesisThis thesis presents a framework for formal system development. The framework is called `RD' which is short for `Reasoning about Designs'. RD integrates proof, development and diagnostic modes of reasoning. Many commonly studied formalisms are shown to be consistent with this framework. A large example based on an industrial problem is given to demonstrate RD. The integration of system design and management is achieved by unifying formal software engineering methods and model-based reasoning. RD formally specifies a complete toolkit for performing system development and then re-using the development as the system description for diagnostic reasoning. RD does not restrict the contributing system analysis methods, rather it maps out and defines the entities and relations common to both. The framework is, in principle, extensible to support other forms of reasoning. The ground technical mechanism of the framework is a novel view of formal system development based on a general implementation relation. Implementation relations are widely studied in formal methods in software engineering where they are often referred to as `refinement'. RD allows refinement relations to be defined in a way that makes expected behaviours and faults of system implementations explicit. Furthermore, a case is made that all well known forms of refinement implicitly support diagnostic reasoning as they can be restated within the framework. RD is an integrated and completely rigorous approach to the core system building tasks of design and management. Despite the large amount of technical detail, the following discussion can be seen as raising many issues that relate to engineering in general. In particular, a formal engineering process should have benefits beyond just the delivery of systems that satisfy their specifications.