252 research outputs found

    Radar Burst Control Based on Constrained Ordinal Optimization under Guidance Quality Constraints

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    Radar burst control has come into use in order to improve the survivability of combat aircraft and ensure operational effectiveness in the increasingly harsh electronic warfare environment. The critical factor in radar burst control is the radar burst timing. In this paper, a novel method is proposed to determine the optimal timing based on constrained ordinal optimization. Taking the combat effectiveness of air-to-air missile as the constraint condition, the constrained ordinal optimization method is applied to the radar burst detection of hybrid control. The optimal burst timing can be selected quickly and efficiently while making the combat effectiveness maximized. Simulation results indicate that the proposed method can significantly improve the searching efficiency of the optimal radar burst timing

    Working Notes from the 1992 AAAI Workshop on Automating Software Design. Theme: Domain Specific Software Design

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    The goal of this workshop is to identify different architectural approaches to building domain-specific software design systems and to explore issues unique to domain-specific (vs. general-purpose) software design. Some general issues that cut across the particular software design domain include: (1) knowledge representation, acquisition, and maintenance; (2) specialized software design techniques; and (3) user interaction and user interface

    Analyzing Granger causality in climate data with time series classification methods

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    Attribution studies in climate science aim for scientifically ascertaining the influence of climatic variations on natural or anthropogenic factors. Many of those studies adopt the concept of Granger causality to infer statistical cause-effect relationships, while utilizing traditional autoregressive models. In this article, we investigate the potential of state-of-the-art time series classification techniques to enhance causal inference in climate science. We conduct a comparative experimental study of different types of algorithms on a large test suite that comprises a unique collection of datasets from the area of climate-vegetation dynamics. The results indicate that specialized time series classification methods are able to improve existing inference procedures. Substantial differences are observed among the methods that were tested

    A decision making aid for evaluating total ship system effectiveness.

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    The aim of this study was to contribute to the knowledge of Total Systems theory and methodologies, by developing an aid to decision making on the effectiveness of complex man-machine organisations. Sponsored by the Ministry of Defence (Navy) as a collaborative research project, the study was to be based on Royal Navy ships and also linked with certain MOD(N) projects working on related effectiveness problems. Initial pre-feasibility, then feasibility studies established a simple model of Effectiveness as the combination of Availability, Performance and Human Factors, which was followed by a more thorough examination of the Availability Function. The development of an Information System designed for the collection and analysis of reliability and maintainability data was central to this phase of the research. This culminates in a comprehensive description of the Phase I hardware, software requirements and information distribution network to be installed and operating commencing in 1983. The Human Factors research was linked to two additional Ministry of Defence (Navy) projects who made available the Human Factors data. This data, collected from five ships of the Type 42 Guided Weapons Destroyer Class, was concerned with the Operations Room organization. Using this data base, a subjective analysis resulted in key indicators being produced which were used with a rating scale technique to develop profiles. Following a systemic overview three interactive indicators - Variable Disjunction of Information, Knowledge and Information Processing were used as the basis of an Information Transfer Function conceptual model. This model, when combined with Systems Interaction Diagrams enabled a Methodology to be designed which was evaluated against a three man-function element within a total Operations Room complement of 33 men. On the premise that the Human Factors function could be transformed to metric data the framework of a Human Factors model was developed, based on an existing Total Ship Availability Model with the potential that these could be combined to produce an Effectiveness model. The information System, the proposed Methodology and the framework of a Ship Effectiveness Model were then incrementally and theoretically linked in order to develop the organisation of a decision making aid for evaluating the effectiveness of complex man-machine systens. The research was not intended to test or validate the decision making aid, as aspects of this will need to be approved by Ministry of Defence (Navy) authorities before proceeding to the next phase of implementing the results so far produced

    Joint University Program for Air Transportation Research, 1988-1989

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    The research conducted during 1988 to 1989 under the NASA/FAA-sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology, Ohio University, and Princeton University. Completed works, status reports, and annotated bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of the year's activities for each university is also presented

    Aeronautical engineering, a continuing bibliography with indexes

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    This bibliography lists 823 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1984

    Smart Urban Water Networks

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    This book presents the paper form of the Special Issue (SI) on Smart Urban Water Networks. The number and topics of the papers in the SI confirm the growing interest of operators and researchers for the new paradigm of smart networks, as part of the more general smart city. The SI showed that digital information and communication technology (ICT), with the implementation of smart meters and other digital devices, can significantly improve the modelling and the management of urban water networks, contributing to a radical transformation of the traditional paradigm of water utilities. The paper collection in this SI includes different crucial topics such as the reliability, resilience, and performance of water networks, innovative demand management, and the novel challenge of real-time control and operation, along with their implications for cyber-security. The SI collected fourteen papers that provide a wide perspective of solutions, trends, and challenges in the contest of smart urban water networks. Some solutions have already been implemented in pilot sites (i.e., for water network partitioning, cyber-security, and water demand disaggregation and forecasting), while further investigations are required for other methods, e.g., the data-driven approaches for real time control. In all cases, a new deal between academia, industry, and governments must be embraced to start the new era of smart urban water systems

    Proceedings of the 9th MIT/ONR workshop on C3 Systems, held at Naval Postgraduate School and Hilton Inn Resort Hotel, Monterey, California June 2 through June 5, 1986

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    GRSN 627729"December 1986."Includes bibliographical references and index.Sponsored by Massachusetts Institute of Technology, Laboratory for Information and Decision Systems, Cambridge, Mass., with support from the Office of Naval Research. ONR/N00014-77-C-0532(NR041-519) Sponsored in cooperation with IEEE Control Systems Society, Technical Committee on C.edited by Michael Athans, Alexander H. Levis

    Performance Evaluation of Serverless Applications and Infrastructures

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    Context. Cloud computing has become the de facto standard for deploying modern web-based software systems, which makes its performance crucial to the efficient functioning of many applications. However, the unabated growth of established cloud services, such as Infrastructure-as-a-Service (IaaS), and the emergence of new serverless services, such as Function-as-a-Service (FaaS), has led to an unprecedented diversity of cloud services with different performance characteristics. Measuring these characteristics is difficult in dynamic cloud environments due to performance variability in large-scale distributed systems with limited observability.Objective. This thesis aims to enable reproducible performance evaluation of serverless applications and their underlying cloud infrastructure.Method. A combination of literature review and empirical research established a consolidated view on serverless applications and their performance. New solutions were developed through engineering research and used to conduct performance benchmarking field experiments in cloud environments.Findings. The review of 112 FaaS performance studies from academic and industrial sources found a strong focus on a single cloud platform using artificial micro-benchmarks and discovered that most studies do not follow reproducibility principles on cloud experimentation. Characterizing 89 serverless applications revealed that they are most commonly used for short-running tasks with low data volume and bursty workloads. A novel trace-based serverless application benchmark shows that external service calls often dominate the median end-to-end latency and cause long tail latency. The latency breakdown analysis further identifies performance challenges of serverless applications, such as long delays through asynchronous function triggers, substantial runtime initialization for coldstarts, increased performance variability under bursty workloads, and heavily provider-dependent performance characteristics. The evaluation of different cloud benchmarking methodologies has shown that only selected micro-benchmarks are suitable for estimating application performance, performance variability depends on the resource type, and batch testing on the same instance with repetitions should be used for reliable performance testing.Conclusions. The insights of this thesis can guide practitioners in building performance-optimized serverless applications and researchers in reproducibly evaluating cloud performance using suitable execution methodologies and different benchmark types

    Aeronautical Engineering: A continuing bibliography with indexes (supplement 177)

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    This bibliography lists 469 reports, articles and other documents introduced into the NASA scientific and technical information system in July 1984
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