8 research outputs found

    What then do we do about computer security?

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    This report presents the answers that an informal and unfunded group at SNL provided for questions concerning computer security posed by Jim Gosler, Sandia Fellow (00002). The primary purpose of this report is to record our current answers; hopefully those answers will turn out to be answers indeed. The group was formed in November 2010. In November 2010 Jim Gosler, Sandia Fellow, asked several of us several pointed questions about computer security metrics. Never mind that some of the best minds in the field have been trying to crack this nut without success for decades. Jim asked Campbell to lead an informal and unfunded group to answer the questions. With time Jim invited several more Sandians to join in. We met a number of times both with Jim and without him. At Jim's direction we contacted a number of people outside Sandia who Jim thought could help. For example, we interacted with IBM's T.J. Watson Research Center and held a one-day, videoconference workshop with them on the questions

    Multidimensional Effects in Optimal Control Calculations for Time-Dependent Nuclear Systems

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    204 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.Physically realistic step function control rod models are shown to be unsolvable under traditional formulations of distributed parameter optimal control theory. Extensions to the theory are proposed, and the method of reduced dimensional control is derived to allow systems of this type to be analyzed using generalized optimality conditions. Distributed parameter optimal control is shown to be a special case of this theory. Reduced dimensional control is shown to be adequate for the analysis of most optimality problems where there are differences in the number of dimensions on which the state variables are defined. The method is then applied to a xenon-iodine oscillation problem in two dimensions. A step function control rod model is examined and compared with an axially homogeneous model. The conditions of optimality are found, and analytical insights concerning the importance of the control rod tip for the optimality condition are obtained. The optimality and normalization conditions are solved numerically for a severe xenon transient. Differences are noted between the cases which can be directly attributed to the proper axial modeling of the control rod.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

    Development of a statistically based access delay timeline methodology.

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    The charter for adversarial delay is to hinder access to critical resources through the use of physical systems increasing an adversary's task time. The traditional method for characterizing access delay has been a simple model focused on accumulating times required to complete each task with little regard to uncertainty, complexity, or decreased efficiency associated with multiple sequential tasks or stress. The delay associated with any given barrier or path is further discounted to worst-case, and often unrealistic, times based on a high-level adversary, resulting in a highly conservative calculation of total delay. This leads to delay systems that require significant funding and personnel resources in order to defend against the assumed threat, which for many sites and applications becomes cost prohibitive. A new methodology has been developed that considers the uncertainties inherent in the problem to develop a realistic timeline distribution for a given adversary path. This new methodology incorporates advanced Bayesian statistical theory and methodologies, taking into account small sample size, expert judgment, human factors and threat uncertainty. The result is an algorithm that can calculate a probability distribution function of delay times directly related to system risk. Through further analysis, the access delay analyst or end user can use the results in making informed decisions while weighing benefits against risks, ultimately resulting in greater system effectiveness with lower cost
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