Refinement for Ontology Evolution in Virtual Enterprises

Virtual enterprise is based on the premise that work should be done where it can be done most optimally. In virtual enterprises, geographical boundaries merge seamlessly. It enables organisations to act in a way of flexibility and ability to adapt to rapid changes on the fly. However, different parties in a virtual enterprise must understand each other before they go further details in business. Ontologies are such kinds of ideal baselines to assist parties to communicate. One of the essential research issues with ontology is how to deal with changes during their evolving cycle. Therefore, ontology refinement is a crucial component in ontology evolution. This paper presents a taxonomy structure focusing on the is-a relations. In particular, the concept of closeness measurement is introduced based on the “distance” estimation. An extended cluster analysis process is provided. According to the algorithm presented, a new concept is generated according to its attributes. Additionally, the refinement mechanisms for primitive operations are proposed. Unlike some other ontology refinement mechanisms which leave ontology consistency checking to human users after modification, our method emphasises the importance of consistency checking by applying description logics which is demonstrated based on the proposed ontology

E-Business Value Process Modelling

E-business development is a considerable complicated task because the underlying logics of e-business and its new processes that are originated from implementing enhanced information technologies to streamline business performance introduce many complex issues. One of the difficulties is to capture the dynamic aspects of e-business that can be used for monitoring the business performance, in a way that could be helpful for the business adaptation to meet competitive advantages. Among many dynamics of e-business, the value system is the most interested one that has recently been addressed. However a value system is at the strategic level with no formal approaches for its representation, which introduces a gap between system modelling and implementation in the e-business development. In this paper, we will investigate a so called value process that can be not only used for value system modeling, but executed for simulation of the resulted model. For the purpose of value process modelling, we will adopt the process algebra approach, which will be integrated with others such as workflow in our modelling environment

Study on house-level microgrids and their power electronics

This thesis introduces the concept of microgrid, and analyzes the capability for Plug-in Electric Vehicles (PHEV) and photovoltaics (PV) to support a residential load during the time when the utility grid has a power outage. A microgrid system model is introduced and simulations have demonstrated the performance of this microgrid in a grid outage. The possible power electronics interfaces in this microgrid configuration is investigated and compared. Several power electronics converters are introduced and simulated to realize different forms of power conversion. The system model of a DC-DC buck converter is formed, and a possible frequency compensator has been designed and simulated for it. This thesis has introduced the feasibility of a house-level microgrid in its theoretical backup performances, hardware implementations and control.Electrical and Computer Engineerin