12,357 research outputs found

    POLITICS OF PUBLIC SUPPORT OF RESEARCH AND EXTENSION

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    Research and Development/Tech Change/Emerging Technologies,

    Application of Computational Fluid Dynamics to the Study of Vortex Flow Control for the Management of Inlet Distortion

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    The present study demonstrates that the Reduced Navier-Stokes code RNS3D can be used very effectively to develop a vortex generator installation for the purpose of minimizing the engine face circumferential distortion by controlling the development of secondary flow. The computing times required are small enough that studies such as this are feasible within an analysis-design environment with all its constraints of time and costs. This research study also established the nature of the performance improvements that can be realized with vortex flow control, and suggests a set of aerodynamic properties (called observations) that can be used to arrive at a successful vortex generator installation design. The ultimate aim of this research is to manage inlet distortion by controlling secondary flow through an arrangements of vortex generators configurations tailored to the specific aerodynamic characteristics of the inlet duct. This study also indicated that scaling between flight and typical wind tunnel test conditions is possible only within a very narrow range of generator configurations close to an optimum installation. This paper also suggests a possible law that can be used to scale generator blade height for experimental testing, but further research in this area is needed before it can be effectively applied to practical problems. Lastly, this study indicated that vortex generator installation design for inlet ducts is more complex than simply satisfying the requirement of attached flow, it must satisfy the requirement of minimum engine face distortion

    Differential Privacy of Aggregated DC Optimal Power Flow Data

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    We consider the problem of privately releasing aggregated network statistics obtained from solving a DC optimal power flow (OPF) problem. It is shown that the mechanism that determines the noise distribution parameters are linked to the topology of the power system and the monotonicity of the network. We derive a measure of "almost" monotonicity and show how it can be used in conjunction with a linear program in order to release aggregated OPF data using the differential privacy framework.Comment: Accepted by 2019 American Control Conference (ACC

    A proposal for a new application of thermal energy from the sea

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    Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1963.MIT copy bound with: Tractor designed for West Africa and other underdeveloped areas / Kenneth Lee Andersen. 1963. -- A test of the Null hypothesis that stock prices fluctuate as a random walk / William Arnold Barnett. 1963. --An experimental study of a simulated candle excited by sound in a vertical tube / Antonio Batek-Taborsky. 1963. -- A stability study of a cantilevered pipe carrying a stream of fluid / Thomas R. Bogan. 1963. -- Comparison of materials for use in high temperature instruments / Terrence Doyle Chatwin. 1963. -- Analysis and improvement of a magnetic suspension in air / Arthur R. Connolly. 1963. -- The use of lasers for machining / Frederick Eliot Cunningham. 1963. -- Nozzle efficiency study at low Reynolds numbers / Georges S. Duval. 1963.Includes bibliographical references (leaves 38-43).by James H. Anderson, Jr.B.S

    Corruption in Latvia

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    The Capitalization of Seller Paid Consessions

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    Using a hedonic pricing model, we analyze the capitalization of total seller paid discount points and closing costs into the price of a house. We hypothesize that sellers are concerned about the sales price net of total seller paid concessions (SPNC), rather than the exact terms of the transaction. Since the SPNC is easily ascertained in the negotiation process, we further hypothesize that total seller paid concessions (TSPC) are fully capitalized into the sales price. To test this hypothesis, sales price is regressed on a set of control variables including TSPC. In this framework, TSPC will be positive and not significantly different from one if concessions are fully capitalized. The empirical results provide support for the capitalization hypothesis. Negotiation strategies and study limitations follow from the empirical results.

    Compositional Set Invariance in Network Systems with Assume-Guarantee Contracts

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    This paper presents an assume-guarantee reasoning approach to the computation of robust invariant sets for network systems. Parameterized signal temporal logic (pSTL) is used to formally describe the behaviors of the subsystems, which we use as the template for the contract. We show that set invariance can be proved with a valid assume-guarantee contract by reasoning about individual subsystems. If a valid assume-guarantee contract with monotonic pSTL template is known, it can be further refined by value iteration. When such a contract is not known, an epigraph method is proposed to solve for a contract that is valid, ---an approach that has linear complexity for a sparse network. A microgrid example is used to demonstrate the proposed method. The simulation result shows that together with control barrier functions, the states of all the subsystems can be bounded inside the individual robust invariant sets.Comment: Submitted to 2019 American Control Conferenc

    The size, origins, and character of Mongolia's informal sector during the transition

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    The explosion of informal entrepreneurial activity during Mongolia's transition to a market economy represents one of the most visible signs of change in this expansive but sparsely populated Asian country. To deepen our understanding of Mongolia's informal sector during the transition, the author merges anecdotal experience from qualitative interviews with hard data from a survey of 770 informals in Ulaanbaatar, from a national household survey, and from official employment statistics. Using varied sources, the author generates rudimentary estimates of the magnitude of, and trends in, informal activity in Mongolia, estimates that are surprisingly consistent with each other. He evaluates four types of reasons for the burst of informal activity in Mongolia since 1990: 1) The crisis of the early and mid-1990s, during which large pools of labor were released from formal employment. 2) Rural to urban migration. 3) The"market's"reallocation of resources toward areas neglected under the old system: services such as distribution and transportation. 4) The institutional environments faced by the formal and informal sectors: hindering growth of the formal sector, facilitating entry for the informal sector. Formal labor markets haven't absorbed the labor made available by the crisis and by migration and haven't fully responded to the demand for new services. The relative ease of entering the informal market explains that market's great expansion. The relative difficulty of entering formal markets is not random but is driven by policy. Improving policies in the formal sector could afford the same ease of entry there as is currently being experienced in the informal sector.Environmental Economics&Policies,Labor Policies,Economic Theory&Research,Health Economics&Finance,Public Health Promotion,Poverty Assessment,Environmental Economics&Policies,Health Economics&Finance,National Governance,Health Monitoring&Evaluation
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