Bernard Butler

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We study the problem of optimising the provisioning of collections of virtual machines (VMs) having different placement constraints (e.g., security and anti-collocation) and characteristics (e.g., memory and disk capacity), given a set of physical machines (PMs) with known specifications, in order to achieve the objective of maximising an IaaS cloud(More)
The performance and scalability of access control systems is growing more important as organisations deploy ever more complex communications and content management systems. Fine-grained access control is becoming more pervasive, so decisions are more frequent and policy sets are larger. We outline a flexible performance testing framework that accepts XACML(More)
The performance and scalability of access control systems is a growing concern as organisations deploy ever more complex communications and content management systems. This paper describes how an (offline) experimental testbed may be used to address performance concerns. To begin, timing measurements are collected from a server component incorporating the(More)
Resource access control policies for an organization are often derived from best practice standards or from high level business policies. To ensure that access control is enforced effectively, these business policies need to be translated into deployable system configurations or lower level policies for multiple diverse systems. These target policy(More)
Computer-assisted recognition of anatomical objects in medical images is at the center of many important clinical applications. Automatic extraction and recognition of human abdominal structures from CT images has been particularly challenging for medical imaging research and applications. Intra-patient and inter-patient spatial, morphological and intensity(More)
There is growing awareness of the need to protect digital resources and services in both corporate and home ICT scenarios. Meanwhile, communication tools tailored for corporations are blurring the line between communication mechanisms and (near) real-time resource sharing. The resulting requirement for near real-time policy-based access control is(More)