9,924 research outputs found

    Advanced flight control system study

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    A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts

    An improved constraint satisfaction adaptive neural network for job-shop scheduling

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    Copyright @ Springer Science + Business Media, LLC 2009This paper presents an improved constraint satisfaction adaptive neural network for job-shop scheduling problems. The neural network is constructed based on the constraint conditions of a job-shop scheduling problem. Its structure and neuron connections can change adaptively according to the real-time constraint satisfaction situations that arise during the solving process. Several heuristics are also integrated within the neural network to enhance its convergence, accelerate its convergence, and improve the quality of the solutions produced. An experimental study based on a set of benchmark job-shop scheduling problems shows that the improved constraint satisfaction adaptive neural network outperforms the original constraint satisfaction adaptive neural network in terms of computational time and the quality of schedules it produces. The neural network approach is also experimentally validated to outperform three classical heuristic algorithms that are widely used as the basis of many state-of-the-art scheduling systems. Hence, it may also be used to construct advanced job-shop scheduling systems.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/01 and in part by the National Nature Science Fundation of China under Grant 60821063 and National Basic Research Program of China under Grant 2009CB320601

    Development of techniques to enhance man/machine communication

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    A four-state random stimulus generator, considered to function as an ESP teaching machine was used to investigate an approach to facilitating interactions between man and machines. A subject tries to guess in which of four states the machine is. The machine offers the user feedback and reinforcement as to the correctness of his choice. Using this machine, 148 volunteer subjects were screened under various protocols. Several whose learning slope and/or mean score departed significantly from chance expectation were identified. Direct physiological evidence of perception of remote stimuli not presented to any known sense of the percipient using electroencephalographic (EEG) output when a light was flashed in a distant room was also studied

    Report on Phase 2.3, Investigation of Welded Highway Bridges. Project IHR-64

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    The object of this investigation was to study the effect of internal flaws on the fatigue behavior of butt-welded connections in mild structural steel, the initiation of fatigue cracks from these flaws and the propagation rates of these cracks in the connections. Since internal flaws occur in many welds it is essential to obtain a better understanding of the behavior of flawed connections so that adequate, yet realistic, code requirements can be established. The study is limited to two major types of defects, porosity and incomplete penetration. The porosity was further subdivided into two categories based on the severity of the defect. The specimens with incomplete penetration were made with an initial 3/16" centrally located crack the full width of the- specimen. The fatigue behavior of the connections with the defects is compared with that of sound welds to observe the effects of the defects on the fatigue strength of the connections. The data are compared with result~ of similar studies found in the literature and also with the AASHO 1970 Specification design requirements. Three of the specimens with incomplete penetration were examined radiographically during the fatigue testing to determine when initiation of the fatigue cracks occurred, and how rapidly they propagated. The results of the crack propagation tests are compared with similar relationships developed for high strength steels. A relationship that better fits the data for mild steel has been developed in a manner similar to that used for the high strength steels.State of Illinois. Department of Transportation. Division of HighwaysU.S. Department of Transportation. Federal Highway Administratio

    User microprogrammable processors for high data rate telemetry preprocessing

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    The use of microprogrammable processors for the preprocessing of high data rate satellite telemetry is investigated. The following topics are discussed along with supporting studies: (1) evaluation of commercial microprogrammable minicomputers for telemetry preprocessing tasks; (2) microinstruction sets for telemetry preprocessing; and (3) the use of multiple minicomputers to achieve high data processing. The simulation of small microprogrammed processors is discussed along with examples of microprogrammed processors

    A study of systems implementation languages for the POCCNET system

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    The results are presented of a study of systems implementation languages for the Payload Operations Control Center Network (POCCNET). Criteria are developed for evaluating the languages, and fifteen existing languages are evaluated on the basis of these criteria
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