32 research outputs found

    The Flying Diamond: A joined aircraft configuration design project, volume 1

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    The results of the analysis conducted on the Joined Wing Configuration study are presented. The joined wing configuration employs a conventional fuselage and incorporates two wings joined together near their tips to form a diamond shape in both plan view and front view. The arrangement of the lifting surfaces uses the rear wing as a horizontal tail and as a forward wing strut. The rear wing has its root at the tip of the vertical stabilizer and is structurally attached to the trailing edge of the forward wing. This arrangement of the two wings forms a truss structure which is inherently resistant to the aerodynamic bending loads generated during flight. This allows for a considerable reduction in the weight of the lifting surfaces. With smaller internal wing structures needed, the Joined Wing may employ thinner wings which are more suitable for supersonic and hypersonic flight, having less induced drag than conventional cantilever winged aircraft. Inherent in the Joined Wing is the capability of the generation of direct lift and side force which enhance the performance parameters

    Giving Users the Steering Wheel for Guiding Resource-Adaptive Systems

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    This material is based upon work supported by the National Science Foundation (NSF) unde

    Modeling Uncertainty of Predictive Inputs in Anticipatory Dynamic Configuration

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    Dynamic adaptive systems based on multiple concurrent applications typically employ optimization models to decide how to allocate scarce resources among the applications and how to tune their runtime settings for optimal quality-of-service according to the preferences of an end user. Traditionally, such systems have avoided dealing with uncertainty by assuming that current snapshots of the relevant inputs are precise and by solving for an optimal system point. To achieve dynamic behavior, a system performs an optimization loop upon discovering changes in the input variables (e.g. changes in the available level of resources) and adapts the applications according to the new optimal solution. Unfortunately, when certain adaptation actions incur costs, such reactive adaptation strategies suffer from a significant shortcoming: several locally optimal decisions over time may often be less than optimal globally. By using predictive information about the future values of the problem inputs, we can model and implement an anticipatory adaptation strategy that helps improve the global behavior of the system in many situations. However, modeling predictions requires representing and dealing with uncertainty from different sources. In this paper, we describe our proposed approach to represent multiple sources of uncertainty and outline algorithms for solving the anticipatory configuration problem with predictive inputs.</p

    Software Selection and Configuration in Mobile Environments: A Utility-Based Approach

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    Users of low-power mobile computing platforms make ad hoc decisions when choosing software components among alternatives and configuring those components. We propose applying utility-theoretic models, which can help determine optimal allocation of scarce resources to applications given the user’s utility and application resource usage. We believe that taking into consideration resource consumption and applying microeconomic models has the potential of improving the user’s satisfaction with the system. In this paper, we formulate the problem, demonstrate the use of a microeconomics-based model on a simple version of the problem, and list possible solutions. Further, we identify issues typical of mobile environments that are not addressed by existing research, and propose ways of tackling these issues

    Task-based self-adaptation

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