5,809 research outputs found

    Microminiature thermocouple monitors own installation

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    Microminiature thermocouple makes precision gas sidewall temperature readings inside large thrust chambers. It is installed by a technique whereby the sensor monitors its own installation to insure against thermal damage to the thermocouple and ensure minimum disturbance to chamber surfaces

    On the design of an interactive biosphere for the GLAS general circulation model

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    Improving the realism and accuracy of the GLAS general circulation model (by adding an interactive biosphere that will simulate the transfers of latent and sensible heat from land surface to atmosphere as functions of the atmospheric conditions and the morphology and physiology of the vegetation) is proposed

    Predicting Fraudulent Behavior: An Examination of Characteristics Commonly Exhibited by Fraudulent DoD Contractors

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    This study examines the relationship between company size, slack, return on investment, and the frequency of fraudulent behavior. A model is proposed in which an increase in company size and a decrease in company slack and return on investment would increase the frequency of fraudulent behavior. A test of the model showed strong support between a relationship between company size and incidents of fraudulent behavior. Additionally, the results suggest that levels of slack may contribute to the frequency of fraud. Further tests provide no support for the relationship between the decrease in return on investment and the increase in the frequency of fraudulent behavior. Overall, the results suggest that large companies with lower levels of slack are more likely to engage in fraudulent behavior. Several explanations for this pattern are explored in the study

    Steady-state and transient operation of a heat-pipe radiator system

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    Data obtained on a VCHP heat-pipe radiator system tested in a vacuum environment were studied. Analyses and interpretation of the steady-state results are presented along with an initial analysis of some of the transient data. Particular emphasis was placed on quantitative comparisons of the experimental data with computer model simulations. The results of the study provide a better understanding of the system but do not provide a complete explanation for the observed low VCHP performance and the relatively flat radiator panel temperature distribution. The results of the study also suggest hardware, software, and testing improvements

    Heat pipe radiators for space

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    An optimized flight-weight prototype fluid-header panel (heatpipe radiator system) was tested in a vacuum environment over a wide range of coolant inlet temperatures, coolant flow rates, and environmental absorbed heat fluxes. The maximum performance of the system was determined. Results are compared with earlier data obtained on a smaller fluid-header feasibility panel, and computer predictions. Freeze-thaw tests are described and the change in thaw recovery time due to the addition of a low-freezing point feeder heat pipe is evaluated. Experimental panel fin-temperature distributions are compared with calculated results

    Supporting Tropos concepts in Agent OPEN

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    The growth of interest in agent-orientation as a new paradigm has introduced the need for developing concepts, tools and techniques for modeling and engineering agent-based software systems. Object technology has been supporting the development of information systems for many years but is now slowly evolving to encompass more recent ideas relating to the concept of "agent". Integrating agent concepts into existing OO methodologies has resulted in several agent-oriented methodologies, one of which is Agent OPEN. In this paper, we evaluate the existing Agent OPEN description against ideas formulated within Tropos, an agent-oriented software development methodology. © Springer-Verlag Berlin Heidelberg 2004

    Heat pipe radiators for space

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    Analysis of the data heat pipe radiator systems tested in both vacuum and ambient environments was continued. The systems included (1) a feasibility VCHP header heat-pipe panel, (2) the same panel reworked to eliminate the VCHP feature and referred to as the feasibility fluid header panel, and (3) an optimized flight-weight fluid header panel termed the 'prototype.' A description of freeze-thaw thermal vacuum tests conducted on the feasibility VCHP was included. In addition, the results of ambient tests made on the feasibility fluid header are presented, including a comparison with analytical results. A thermal model of a fluid header heat pipe radiator was constructed and a computer program written. The program was used to make a comparison of the VCHP and fluid-header concepts for both single and multiple panel applications. The computer program was also employed for a parametric study, including optimum feeder heat pipe spacing, of the prototype fluid header

    A tiling approach to eight identities of Rogers

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    AbstractBeginning in 1893, L.J. Rogers produced a collection of papers in which he considered series expansions of infinite products. Over the years, his identities have been given a variety of partition-theoretic interpretations and proofs. These existing combinatorial techniques, however, do not highlight the similarities and the subtle differences seen in so many of these remarkable identities. It is the goal of this paper to present a new combinatorial approach that unifies numerous q-series identities. The eight identities of Rogers that appear in G.E. Andrews’ 1986 CBMS monograph on q-series will serve as a basis for the collection of identities studied in this paper

    Global Modeling, Field Campaigns, Upscaling and Ray Desjardins

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    In the early 1980's, it became apparent that land surface radiation and energy budgets were unrealistically represented in Global Circulation models (GCM's), Shortly thereafter, it became clear that the land carbon budget was also poorly represented in Earth System Models (ESM's), A number of scientific communities, including GCM/ESM modelers, micrometeorologists, satellite data specialists and plant physiologists, came together to design field experiments that could be used to develop and validate the contemporary prototype land surface models. These experiments were designed to measure land surface fluxes of radiation, heat, water vapor and CO2 using a network of flux towers and other plot-scale techniques, coincident with satellite measurements of related state variables, The interdisciplinary teams involved in these experiments quickly became aware of the scale gap between plot-scale measurements (approx 10 - 100m), satellite measurements (100m - 10 km), and GCM grid areas (l0 - 200km). At the time, there was no established flux measurement capability to bridge these scale gaps. Then, a Canadian science learn led by Ray Desjardins started to actively participate in the design and execution of the experiments, with airborne eddy correlation providing the radically innovative bridge across the scale gaps, In a succession of brilliantly executed field campaigns followed up by convincing scientific analyses, they demonstrated that airborne eddy correlation allied with satellite data was the most powerful upscaling tool available to the community, The rest is history: the realism and credibility of weather and climate models has been enormously improved enormously over the last 25 years with immense benefits to the public and policymakers
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