4,501 research outputs found

    Toward Clemens' Conjecture in degrees between 10 and 24

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    We introduce and study a likely condition that implies the following form of Clemens' conjecture in degrees dd between 10 and 24: given a general quintic threefold FF in complex \IP^4, the Hilbert scheme of rational, smooth and irreducible curves CC of degree dd on FF is finite, nonempty, and reduced; moreover, each CC is embedded in FF with balanced normal sheaf \O(-1)\oplus\O(-1), and in \IP^4 with maximal rank.Comment: Plain Tex, This eleven page paper is a joint manuscript, produced in connection with the first author's participation in the conference "Geometry and Physics", Zlatograd, Bulgaria, August 28 - Sept.2, 1995." This version contains a small change in Remark (3.3); the hope expressed there has been refine

    Preliminary analysis of a downsized advanced gas-turbine engine in a subcompact car

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    Relative fuel economy advantages exist for a ceramic turbine engine when it is downsized for a small car were investigated. A 75 kW (100 hp) single shaft engine under development was analytically downsized to 37 kW (50 hp) and analyzed with a metal belt continuously variable transmission in a synthesized car. With gasoline, a 25% advantage was calculated over that of a current spark ignition engine, scaled to the same power, using the same transmission and car. With diesel fuel, a 21% advantage was calculated over that of a similar diesel engine vehicle

    Operating condition and geometry effects on low-frequency afterburner combustion instability in a turbofan at altitude

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    Three afterburner configurations were tested in a low-bypass-ratio turbofan engine to determine the effect of various fuel distributions, inlet conditions, flameholder geometry, and fuel injection location on combustion instability. Tests were conducted at simulated flight conditions of Mach 0.75 and 1.3 at altitudes from 11,580 to 14,020 m (38,000 to 46,000 ft). In these tests combustion instability with frequency from 28 to 90 Hz and peak-to-peak pressure amplitude up to 46.5 percent of the afterburner inlet total pressure level was encountered. Combustion instability was suppressed in these tests by varying the fuel distribution in the afterburner

    Altitude test of several afterburner configurations on a turbofan engine with a hydrogen heater to simulate an elevated turbine discharge temperature

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    A performance test of several experimental afterburner configurations was conducted with a mixed-flow turbofan engine in an altitude facility. The simulated flight conditions were for Mach 1.4 at two altitudes, 12,190 and 14,630 meters. Turbine discharge temperatures of 889 and 1056 K were used. A production afterburner was tested for comparison. The research afterburners included partial forced mixers with V-gutter flameholders, a carburetted V-gutter flameholder, and a triple ring V-gutter flameholder with four swirl-can fuel mixers. Fuel injection variations were included. Performance data shown include augmented thrust ratio, thrust specific fuel consumption, combustion efficiency, and total pressure drop across the afterburner

    Reactions of Na/plus/, K/plus/, and Ba/plus/ ions with O2, NO, and H2O molecules

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    Investigating ion molecule reactions of sodium, potassium, and barium ions with oxygen, nitric oxide, and water in drift tube mass spectromete

    A class of well-posed parabolic final value problems

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    This paper focuses on parabolic final value problems, and well-posedness is proved for a large class of these. The clarification is obtained from Hilbert spaces that characterise data that give existence, uniqueness and stability of the solutions. The data space is the graph normed domain of an unbounded operator that maps final states to the corresponding initial states. It induces a new compatibility condition, depending crucially on the fact that analytic semigroups always are invertible in the class of closed operators. Lax--Milgram operators in vector distribution spaces constitute the main framework. The final value heat conduction problem on a smooth open set is also proved to be well posed, and non-zero Dirichlet data are shown to require an extended compatibility condition obtained by adding an improper Bochner integral.Comment: 16 pages. To appear in "Applied and numerical harmonic analysis"; a reference update. Conference contribution, based on arXiv:1707.02136, with some further development

    A type system for components

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    In modern distributed systems, dynamic reconfiguration, i.e., changing at runtime the communication pattern of a program, is chal- lenging. Generally, it is difficult to guarantee that such modifications will not disrupt ongoing computations. In a previous paper, a solution to this problem was proposed by extending the object-oriented language ABS with a component model allowing the programmer to: i) perform up- dates on objects by means of communication ports and their rebinding; and ii) precisely specify when such updates can safely occur in an object by means of critical sections. However, improper rebind operations could still occur and lead to runtime errors. The present paper introduces a type system for this component model that extends the ABS type system with the notion of ports and a precise analysis that statically enforces that no object will attempt illegal rebinding

    A Student\u27s Perspective of Learning on a Dedicated Education Unit

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    It is the intent of this honors project to give a student’s perspective of learning in the Dedicated Education Unit (DEU) on Bridge 7 at Rhode Island Hospital. Bridge 7 is a 38-bed unit specializing in general medical surgical patient care services. A student’s perspective is illustrated by journal entries written from each clinical experience over the course of one semester, during the course Adult Health II. In addition to a student’s perspective, it is the intention to compare the learning experience on the DEU, to the traditional model of clinical learning. This project will include current nursing research that focuses on different areas of dedicated education unit learning. Findings from these nursing research articles will be compared and contrasted to a student’s perspective of the same outcomes. Prior to each clinical day, students set personal goals. These personal goals will be addressed, with a focus on how learning on a DEU enhanced goal attainment. Lastly, well-known nursing theorist Pat Benner’s conceptual model of how nurses evolve from novice to expert will be utilized and directly incorporated into the student’s perspective
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