Using grid resources to execute scientific applications requiring a large amount of computing power is attractive but not easy from the user point of view. Vigne is a grid operating system designed to provide users wi...
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ISBN:
(纸本)9780769526381;0769526381
Using grid resources to execute scientific applications requiring a large amount of computing power is attractive but not easy from the user point of view. Vigne is a grid operating system designed to provide users with a simplified view of a grid. Vigne deals with the huge number of nodes in a large-scale grid and with the nodes' dynamic behavior by using peer-to-peer overlays as a keystone. In this paper, we show why it is highly desirable to use structured and unstructured peer-to-peer overlays for building the high-level services of Vigne grid operating system. To show the interest of our approach, we detail the features of two Vigne services built on top of peer-to-peer overlays. We also present experimental results obtained on the Grid'5000 testbed showing the scalability of the Vigne infrastructure based on overlays and its practical interest for the implementation of Vigne distributed services
In many IEEE 802.11 WLAN deployments, wireless clients have a choice of access points (AP) to connect to. In current systems, clients associate with the access point with the strongest signal to noise ratio. However, ...
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In many IEEE 802.11 WLAN deployments, wireless clients have a choice of access points (AP) to connect to. In current systems, clients associate with the access point with the strongest signal to noise ratio. However, such an association mechanism can lead to unequal load sharing, resulting in diminished system performance. In this paper, we first provide a numerical approach based on stochastic dynamic programming to find the optimal client-AP association algorithm for a small topology consisting of two access points. Using the value iteration algorithm, we determine the optimal association rule for the two-AP topology. Next, utilizing the insights obtained from the optimal association rule for the two-AP case, we propose a near-optimal heuristic that we call RAT. We test the efficacy of RAT by considering more realistic arrival patterns and a larger topology. Our results show that RAT performs very well in these scenarios as well. Moreover, RAT lends itself to a fairly simple implementation.
In this paper, we present a model-based approach for estimating fault conditions in an aircraft. We formulate fault estimation as a convex optimization problem, where estimates are obtained by solving a constrained qu...
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In this paper, we present a model-based approach for estimating fault conditions in an aircraft. We formulate fault estimation as a convex optimization problem, where estimates are obtained by solving a constrained quadratic program (QP). A moving horizon framework is used to enable recursive implementation of the constrained QP of fixed size. The estimation scheme takes into account a priori known monotonicity constraints on the faults. Monotonicity implies that the fault conditions can only deteriorate with time. We validate the proposed estimation scheme on a detailed nonlinear simulation model of the Aerosonde unmanned aerial vehicle (UAV) in the presence of winds and turbulence. An excellent performance of the developed approach is demonstrated.
The RTSJ memory model propose a mechanism based on a scope three containing all region-stacks in the system and a reference-counter collector. In order to avoid reference cycles among regions on the region-stack, RTSJ...
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ISBN:
(纸本)9781424400546
The RTSJ memory model propose a mechanism based on a scope three containing all region-stacks in the system and a reference-counter collector. In order to avoid reference cycles among regions on the region-stack, RTSJ defines the single parent rule. The given algorithms to maintain the region-stack structure are not compliant with the defined parentage relation. More over, the suggested algorithms to maintain the single parent rule introduces race carrier conditions on the application behaviour. This paper proposes alternative approaches in order to avoid this problem
Software realization of distributed computing systems (DCS) is achieved through the component based software development (CBSD) approach. DCS are generated by composing individual components. While creating such DCS, ...
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Software realization of distributed computing systems (DCS) is achieved through the component based software development (CBSD) approach. DCS are generated by composing individual components. While creating such DCS, care must be taken to include the aspects of access control and obtain the resultant access control policy as a function of individual access control policies of the underlying components. A formal framework is needed to achieve this task of composing access control policies. In this paper, we propose an algebra that enables the composition of access control policies of individual components using the interaction patterns between them. A case study is presented which justifies the proposed algebra
LC/MS is a successful analysis technique for the statistical analysis used in several branches of biology. It requires an intense screening and combination of the raw data, which is usually done with programs and libr...
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LC/MS is a successful analysis technique for the statistical analysis used in several branches of biology. It requires an intense screening and combination of the raw data, which is usually done with programs and libraries invoked by scripts in the domain-specific statistics language S or R. We show here how to model and implement this complex workflow in a service-oriented fashion, using the jABC service definition environment and jETI for remote service integration and execution.
In this paper a two-step trajectory planning algorithm is applied to generate suitable trajectories for an autonomous parking maneuver of a car. It is shown how important requirements of the automotive industry can be...
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In this paper a two-step trajectory planning algorithm is applied to generate suitable trajectories for an autonomous parking maneuver of a car. It is shown how important requirements of the automotive industry can be met with the proposed approach. Furthermore, some details on the implementation of the algorithm are given, which are essential to obtain reasonable computation times
Software development tools need to support more and more phases of the entire development process, because applications must be developed more correctly and efficiently. The tools therefore need to integrate sophistic...
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Software development tools need to support more and more phases of the entire development process, because applications must be developed more correctly and efficiently. The tools therefore need to integrate sophisticated checkers, generators and transformations. A feasible approach to ensure high quality of such add-ins is to base them on sound formal foundations. In order to know where such add-ins will fit, we investigate the use of an existing successful commercial tool and identify suitable places for adding formally supported checking, transformation and generation modules. The paper concludes with a discussion of feasibility of developing the proposed add-ins and how to give conditions such that they will actually be used.
The novel parallel/distributed application control method, discussed in this paper, is based on the use of global states monitoring. Application processes report their local states to monitors. The monitors construct ...
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ISBN:
(纸本)9780769526381;0769526381
The novel parallel/distributed application control method, discussed in this paper, is based on the use of global states monitoring. Application processes report their local states to monitors. The monitors construct global states, analyze them and send control signals to processes to stimulate necessary actions. A number of application areas of this control method are examined. Tests results and gained experience are presented for irregular computation, load balancing and dynamic workflow implementations. It is shown, that the new control method can lead to a better performance than message passing and that it provides a useful and convenient framework, facilitating program development and maintenance
Model predictive sampled-data control of linear continuous-time plants is considered. The time-discretization of the prediction horizon may be non-linear, in order to reduce the number of optimization variables for a ...
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Model predictive sampled-data control of linear continuous-time plants is considered. The time-discretization of the prediction horizon may be non-linear, in order to reduce the number of optimization variables for a given prediction horizon length. This is done for the purpose of allowing faster implementation. While the method is aimed at constrained systems, this paper focuses on the achievable performance of such control strategies for unconstrained systems. A general solution to the finite-horizon optimal control problem is derived for a prediction horizon of arbitrary time-discretization. The model predictive control strategy is consequently derived, and the optimal control input shown to be given by a time-invariant state feedback expression. Three non-linear prediction horizon time-discretization schemes are proposed, and their relative merits discussed. The benefit of employing the presented control strategy is demonstrated by a satellite attitude control case study. The same case study is further used to highlight limitations of and performance differences between the three proposed prediction horizon time-discretization schemes.
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