37,993 research outputs found

    Feasibility study of an Integrated Program for Aerospace vehicle Design (IPAD). Volume 1B: Concise review

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    Reports on the design process, support of the design process, IPAD System design catalog of IPAD technical program elements, IPAD System development and operation, and IPAD benefits and impact are concisely reviewed. The approach used to define the design is described. Major activities performed during the product development cycle are identified. The computer system requirements necessary to support the design process are given as computational requirements of the host system, technical program elements and system features. The IPAD computer system design is presented as concepts, a functional description and an organizational diagram of its major components. The cost and schedules and a three phase plan for IPAD implementation are presented. The benefits and impact of IPAD technology are discussed

    Feasibility study of an Integrated Program for Aerospace vehicle Design (IPAD). Volume 1A: Summary

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    IPAD was defined as a total system oriented to the product design process. This total system was designed to recognize the product design process, individuals and their design process tasks, and the computer-based IPAD System to aid product design. Principal elements of the IPAD System include the host computer and its interactive system software, new executive and data management software, and an open-ended IPAD library of technical programs to match the intended product design process. The basic goal of the IPAD total system is to increase the productivity of the product design organization. Increases in individual productivity were feasible through automation and computer support of routine information handling. Such proven automation can directly decrease cost and flowtime in the product design process

    A Factor Framework for Experimental Design for Performance Evaluation of Commercial Cloud Services

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    Given the diversity of commercial Cloud services, performance evaluations of candidate services would be crucial and beneficial for both service customers (e.g. cost-benefit analysis) and providers (e.g. direction of service improvement). Before an evaluation implementation, the selection of suitable factors (also called parameters or variables) plays a prerequisite role in designing evaluation experiments. However, there seems a lack of systematic approaches to factor selection for Cloud services performance evaluation. In other words, evaluators randomly and intuitively concerned experimental factors in most of the existing evaluation studies. Based on our previous taxonomy and modeling work, this paper proposes a factor framework for experimental design for performance evaluation of commercial Cloud services. This framework capsules the state-of-the-practice of performance evaluation factors that people currently take into account in the Cloud Computing domain, and in turn can help facilitate designing new experiments for evaluating Cloud services.Comment: 8 pages, Proceedings of the 4th International Conference on Cloud Computing Technology and Science (CloudCom 2012), pp. 169-176, Taipei, Taiwan, December 03-06, 201

    Reliability models for dataflow computer systems

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    The demands for concurrent operation within a computer system and the representation of parallelism in programming languages have yielded a new form of program representation known as data flow (DENN 74, DENN 75, TREL 82a). A new model based on data flow principles for parallel computations and parallel computer systems is presented. Necessary conditions for liveness and deadlock freeness in data flow graphs are derived. The data flow graph is used as a model to represent asynchronous concurrent computer architectures including data flow computers

    Study of Saturn 1B facilities and equipment for improved launch control of AAP missions. Volume 1 - Executive summary, 1 December 1968 - 1 February 1970

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    Saturn 1B facilities, launch delay, and ground support equipment study for AAP launch contro

    Modeling the Influence of Land Use Developments on Transportation System Performance

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    The growth in the urban population has influenced urban sprawl, congestion, and subsequently, delays on the existing road infrastructure. New land use developments occur in every part of the city due to rapid economic development and to meet the demand for better living standards. The induced traffic volume generated from such land use developments often results in increased congestion and vehicular delay on the existing roads. With recent advancements in the technology, it is possible to capture continuous, and comprehensive travel time data for every major corridor in a city. Therefore, the goal of this research is to model the influence of land use developments on travel time variations to improve the mobility of people and goods. Data for 259 road links were selected within the city of Charlotte, North Carolina (NC). Three years of travel time data, from the year 2013 to the year 2015, were collected from the private agency. Thirty-five different types of land use developments were considered in this research. The spatial dependency was incorporated by considering the land use developments within 0.5 miles, 1 mile, 2 miles, and 3 miles of the selected road link. Forty-eight statistical models were developed. The results obtained indicate that land use developments have a significant influence on travel times. Different land use categories contribute to the average travel time based on the buffer width, area type, and the link speed limit. Developing the models by classifying the links based on the speed limit (\u3c 45 mph, 45 to 50 mph, and \u3e 50 mph) was observed to be the best approach to examine the relationship between land use developments and the average travel time. Also, typically travel time on a selected road link is higher during the evening peak period compared to the morning peak and the afternoon off-peak period. Further, the results obtained indicate that the number of lanes and the posted speed limit are negatively associated with the travel time of the selected link

    Smart microgrids and virtual power plants in a hierarchical control structure

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    In order to achieve a coordinated integration of distributed energy resources in the electrical network, an aggregation of these resources is required. Microgrids and virtual power plants (VPPs) address this issue. Opposed to VPPs, microgrids have the functionality of islanding, for which specific control strategies have been developed. These control strategies are classified under the primary control strategies. Microgrid secondary control deals with other aspects such as resource allocation, economic optimization and voltage profile improvements. When focussing on the control-aspects of DER, VPP coordination is similar with the microgrid secondary control strategy, and thus, operates at a slower time frame as compared to the primary control and can take full advantage of the available communication provided by the overlaying smart grid. Therefore, the feasibility of the microgrid secondary control for application in VPPs is discussed in this paper. A hierarchical control structure is presented in which, firstly, smart microgrids deal with local issues in a primary and secondary control. Secondly, these microgrids are aggregated in a VPP that enables the tertiary control, forming the link with the electricity markets and dealing with issues on a larger scale
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