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Policy-based management is typically used to manage large and complex systems, e.g. the management of telecommunications networks. When collaborating multi-disciplinary managers try to create policies from their own viewpoint they are hindered by a lack of a common vocabulary and an inability to understand how the complex system currently operates and how it is constrained. For example, modern telecoms...
Routing of contextual information within ubiquitous computing environments is a key challenge that must be tackled for such environments to be successful. It is accepted that such routing systems need to cope with mobile and volatile sources and destinations of contextual information, and semantic-based publish subscribe systems have been proposed as a means to support this. However such systems typically...
Given the diversity of information and services that an individual will want to offer and/or share in a ubiquitous computing environment, it is critical that the individual is provided with mechanisms to manage access and usage to their resources. Mirroring real life, a natural concept for people to grasp when assigning ability to access or use resources is one of "trustworthiness". In previous...
With ontologies increasing in number and becoming more common place, there is an ever increasing need for tools and techniques to cope with diversity and heterogeneity. We believe that the interfaces to ontology management tools will need to be engineered to allow ordinary non technical people to be able to use them effectively. This paper reports upon a mapping process using the dasiataggingpsila...
This paper presents the design and measured results for micro-fabricated inductors suitable for use in high frequency (> 10 MHz), low power (1 -2 W) dc-dc converters. The design has focused on maximizing inductor efficiency for a given converter specification. Inductors in the range of 100 nH to 300 nH have been fabricated and tested. The small signal measurements show a relatively flat inductance...
The detailed design and optimisation of a high current monolithic point-of-load (POL) buck converter is presented in this paper. The approach taken is to identify the major design issues which account for power losses and represent them as a function of the power device width. Having identified these loss sources and quantified them, the optimum power device sizes are obtained for a converter with...
This work examines the impact of packaging parasitics on the efficiency of a synchronous DC-DC buck converter. An analytical model of the losses in the converter is developed and this is compared to practical results at switching frequencies in the range of 1-2 MHz. The effect that the packaging parasitic inductance has on efficiency is highlighted by predicting the expected losses from a converter...
Knowledge workers rely on collaboration with a large number of knowledge. Even highly experienced knowledge workers find it difficult to keep up to date with resources available to help them complete a particular goal. This paper proposed a context-aware resource recommendation system (CARRS) to help tackle this problem. When a knowledge worker is working on a particular goal, CARRS continuously perceives...
The management of dynamic spectrum access requires the coordination of administrative functions across multiple organizations, from regulators to secondary market operators and commons cooperatives. Policy-based management approaches to dynamic spectrum access must therefore support a wide range of organizational types and handle the relationships between policies authored separately within those...
In this paper we propose a holistic approach to modeling the management of dynamic spectrum access (DSA). We argue that the range to issues involved requires not just a management scheme, but also a meta-management scheme whereby management processes are monitored, analyzed and improved. In this way different proposals for management can be refined through interaction in a dialectic that reacts to...
The trends for pushing more operational intelligence towards network elements to achieve more context-aware and self-managing behavior often requires elements to gather network knowledge without necessarily binding explicitly to all of the potential sources of that knowledge. Though event-based publish-subscribe models allow efficient distribution of knowledge where the event types are known globally,...
As context-aware systems become more widespread and mobile there is an increasing need for a common distributed event platform for gathering context information and delivering to context-aware applications. The likely heterogeneity across the body of context information can be addressed using runtime reasoning over ontology-based context models. However, existing knowledge-based reasoning is not typically...
When deploying collaborative applications such as instant messaging in ubiquitous computing environments significant enhancements can be afforded by offering additional context information, such as location information. However, such environments exert key challenges such as increased diversity of ownership and ad hoc, intermittent network connectivity that suits more decentralized computing architectures...
It is possible to impose the will of the user or administrator through the specification of policies. These policies reflect the users or administrators goals; however the context in which these goals operate can vary greatly. This paper builds on our previous work where we demonstrated the creation and use of policies that had trust conditions embedded. The work reported on here exposes these trust...
This paper aims to provide a practical insight into the use of a novel resonant gate drive system to efficiently drive both the power switches in a switched mode power supply, without the requirement for level shifting or bootstrapping circuitry. At present there are two popular methods to drive high side N-channel devices in low voltage applications. The circuit presented here overcomes the limitations...
Magneto-acoustic emission (MAE) and magnetic Barkhausen noise (MBN) sensing techniques were developed and employed to characterise plastically deformed and heat-treated AISI 430 ferritic stainless steel samples. These results have been compared to the mechanical hardness, coercivity and residual stress of the samples. MAE and MBN were shown to decrease with increasing permanent material deformation...
Background: ACC/ASNC guidelines recommend vasodilator stress for the diagnosis and risk stratification of patients with left bundle branch block (LBBB) regardless of exercise capacity. There are no data comparing exercise and vasodilator gated stress myocardial perfusion imaging (MPI) for risk stratification of patients with LBBB.Methods: A consecutive series of 418 patients with LBBB underwent exercise...
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