Environmentally friendly renewable energy technologies such as wind and solar energy systems are among the fleet of new generating technologies driving the demand for distributed generation of electricity. Power Electronics has initiated the next tech¬nological revolution and enables the connection of distributed generation (DG) systems to the grid. The challenge is to achieve system functionality without extensive custom engineering, yet still have high system reliability and generation placement flexibility. Nowadays, it is a general trend to increase the electricity production using DG systems. If these systems are not properly controlled, their connection to the utility network can generate problems on the grid side. Therefore, considerations about power generation, safe running and grid synchronization must be done before connecting these systems to the utility network. This thesis introduces a new grid-synchronization, or more visibly a new “power signal processor” adaptive notch filtering (ANF) tool that can potentially stimulate much interest in the field and provide improvement solutions for grid-connected operation of DG systems. The processor is simple and offers high degree of immunity and insensitivity to power system disturbances, harmonics and other types of pollutions that exist in the grid signal. The processor is capable of decomposing three-phase quantities into symmetrical components, extracting harmonics, tracking the frequency variations, and providing means for voltage regulation and reactive power control. In addition, this simple and powerful synchronization tool will simplify the control issues currently challenging the integration of distributed energy technologies onto the electricity grid. All converter-interfaced equipments like FACTS (flexible ac transmission systems) and Custom Power Controllers will benefit from this technique. The theoretical analysis is presented, and simulation and experimental results confirm the validity of the analytical work. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-01-27 11:37:07.279

This job is considered about mobile technologies, and mobile devices data synchronization problem. Presented trading agent‘s mobile work places and server data synchronization solution, wich was developed using free software.

Today, it is a major issue for mobile applications to maintain a replica state of the server on mobile devices. This creates the need to keep data on both the server and the mobile. In such cases, when the data changes on the server, the new state of the data has to be updated on the mobile in order to maintain a consistent view of the data flow. However, mobile devices communicate over wireless mediums (.e.g., Bluetooth, Wi-Fi, 3.5G/4G, etc.) which can experience intermittent connectivity. The volatility of the network is also influenced by low-bandwidth. The direct effects of these issues are high latency and inconsistency issues between the data on the mobile clients and the remote servers. In this work, I present a detail review on the topic of data synchronization in mobile networks. Then, a generic architecture called MobiQ is proposed which can keep working in an offline mode to record local modifications and can synchronize with the remote servers when connectivity is restored. This is achieved through the proposal of an efficient synchronization protocol which combines different synchronization and replication strategies. Moreover, the MobiQ framework provides a secured environment to work with data. The implemented architecture is designed and tested in mobile questionnaire system and the result is encouraging.

No description available.

Thesis (Ph. D.)--Ohio University, March, 1999. / Title from PDF t.p.

Thesis (Ph. D.)--University of North Texas, May, 2008. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 88-99) Also available in print.

Thesis (Ph. D.)--OGI School of Science & Engineering at OHSU, 2004. / Includes bibliographical references (leaves 351-358).

With the advent of multicore processors, there is an increasing amount of interest in building concurrent applications capable of fully utilising their features. Developing applications for these platforms to take full advantage of the power of multicore capabilities remains a complex, error-prone, and challenging endeavour. Unfortunately, concurrency is not uniformly and externally expressed in most existing application models. The result is that concurrency and thread management are hidden within objects or components and intermixed with their functionalities. After demonstrating the tangling of code that results from the interaction of these two major concerns, this thesis describes a method of improving the concurrent program by applying a novel technique to separate the concerns: aspect-oriented programming, which aims to encapsulate concerns that crosscut the main program flow in separate entities into aspects. The most mature aspect-oriented tool available at the time this project was being undertaken is AspectJ, which is an extension of Java. AspectJ can be used to write an aspect to a separate concern in a sequential program to avoid code tangling, but it is often inapplicable for concurrent programs. The problem lies in the fact that the points where parallelisation should occur are not natural join points in AspectJ (i.e. points where AspectJ can intervene). Consequently, this thesis proposes a set of fine-grained join points capable of completely handling concurrent programs. This model goes beyond present AspectJ models and demonstrates the need to recognise complex behaviour for an effective separation of concerns. Finally, aspects for implementing concurrent programs according to different schemes are presented, together with evaluation results. This highlights the flexibility of aspects for implementing concurrent programs, a flexibility which is always a cross-cutting concern with respect to the main concern of base applications.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering