Staff publications (CDS)
Permanent URI for this collection
Browse
Browsing Staff publications (CDS) by Type "Postprint"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Open Access The dependence of radar target detectability on array weighting function(2009-07-14T14:40:00Z) Alabaster, Clive M.; Hughes, Evan J.This paper describes simulation work to assess the detectability of targets by an airborne fire control radar (FCR) operating in a medium pulse repetition frequency (PRF) mode in the presence of strong ground clutter as a function of transmitting and receiving array weighting functions.Item Open Access Information Security management: A human challenge?(Elsevier, 2008-11) Ashenden, DebiThis paper considers to what extent the management of Information Security is a human challenge. It suggests that the human challenge lies in accepting that individuals in the organisation have not only an identity conferred by their role but also a personal and social identity that they bring with them to work. The challenge that faces organisations is to manage this while trying to achieve the optimum configuration of resources in order to meet business objectives. The paper considers the challenges for Information Security from an organisational perspective and develops an argument that builds on research from the fields of management and organisational behaviour. It concludes that the human challenge of Information Security management has largely been neglected and suggests that to address the issue we need to look at the skills needed to change organisational culture, the identity of the Information Security Manager and effective communication between Information Security Managers, end users and Senior Managers.Item Open Access An investigation into set back force simulation in composition B fillings subjected to hot gun scenarios(2008-05-28T14:50:30Z) Cartwright, M.; Delany, P.Ammunition loaded into large calibre gun chambers, which have been heated by previous firings, can enter a hot-gun state; conservatively defined as hot if 50 rounds or more are fired in a four-hour period. In this state the temperatures of the explosive fill, such as Composition B, may easily exceed their qualification temperatures. This is potentially dangerous if the weapon misfires either by cook-off or premature shell ignition. Currently there are no standard tests that can be used to assess the behaviour of Composition B filled munitions in a simulated hot-gun condition. During firing some of the energy can be transferred to the explosive fill. Defects induced by melting and/or re-solidification of the Composition B will lead to a greater chance of accidental initiation of the explosive due to setback forces creating hotspots and ultimately resulting in an accidental in-bore explosion. The aim of this research was to investigate the conditions of this accidental initiation of Composition B in a hot gun situation at the time the projectile is likely to be cleared from the gun. It investigated whether this situation can be simulated cost effectively by examining the sensitivity of Composition B samples that were thermally conditioned in accordance with calculated temperature-time profiles. A target assembly was designed to mimic setback forces by using projectile impact. A series of tests conducted on these composition B filled targets, which had been subjected to hot gun conditions, were performed at the Cranfield Ordnance Test and Evaluation Centre (COTEC) to simulate setback effects at shot start. Mechanical energy was delivered by an impacting sabot launched from a nitrogen gas powered gun. Post firing simulation and analysis of materials were used to determine the mechanism of initiation and the severity of the event compared to the amount of force the samples were subjected to.Item Open Access Performance Issues for Vertex Elimination Methods in Computing Jacobians using Automatic Differentiation.(Springer-Verlag, 2002) Tadjouddine, Mohamed; Forth, Shaun A.; Pryce, John D.; Reid, John K.In this paper, we present first results from EliAD, a new automatic differentiation tool. EliAD uses the Elimination approach for Automatic Differentation first advocated by Griewank and Reese (Automatic Differentiation of Algorithms, SIAM, 1991 p126-135). EliAD implements this technique via source-transformation, writing new Fortran code for the Jacobians of functions defined by existing Fortran code. Our results are from applying EliAD to the Roe flux routine commonly used in computational fluid dynamics. We show that we can produce code that calculates the associated flux Jacobian approaching or in excess of twice the speed of current state-of-the-art automatic differentiation tools. However, in order to do so we must take into account the architecture on which we are running our code. In particular, on processors that do not support out-of-order execution, we must reorder our derivative code so that values may be reused while in arithmetic registers in order that the floating point arithmetic pipeline may be kept full.Item Open Access Source Transformation for MATLAB Automatic Differentiation.(Springer-Verlag, 2005-12) Kharche, Rahul V.; Forth, Shaun A.We present MSAD, a source transformation implementation of forward mode automatic differentiation for MATLAB. MSAD specialises and inlines operations from the fmad and derivvec classes of the MAD package. The operator overloading overheads inherent in MAD are eliminated while preserving the derivvec class's optimised derivative combination operations. Compared to MAD, results from several test cases demonstrate significant improvement in efficiency across all problem sizes.Item Open Access Tacit knowledge elicitation and measurement in research organisations: A methodological approach(2008-05-28T15:03:10Z) Garcia-Perez, Alexeis; Mitra, AmitContextual complexities as a result of the nature of knowledge based resources of organisations are increasingly the bases of competitive advantage. In the third generation of KM theories and techniques, intra-organisational flows of knowledge resources have become as important as the resources themselves. Management of such flows is an imperative rather than an alternative for most organisations. When attempting to implement effective KM strategies, most organisations assume complete awareness of what knowledge-based resources they own and which elements of these need to be shared. However, such an assumption may not always be valid. While many scholars have conducted research into measurement and management of explicit knowledge, limited progress has been made in applying similar processes to tacit knowledge resources. The KM research and practice communities agree on the importance of identifying and measuring tacit knowledge-based resources, while absence of suitable instruments designed to apply to it continues to be a problem. This paper outlines a method to identify and measure organisational tacit knowledge-based resources based on the concepts of tacit knowledge stocks, their intra-organisational flows, and enablers and inhibitors of such flows. The research paper describes the method, and the process of its validation, performed within a research and development organisation.