5,436 research outputs found

    Numerical analysis of flow and heat transfer in the VAFB LOX storage Dewar tank

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    The present report describes numerical simulation of three-dimensional transient distributions of velocity and temperature of liquid oxygen (LOX) in the LOX Dewar tank of Vendenberg Air Force Base (VAFB). The present analyses cover the replenish time period only. Four test cases have been considered. For all four cases, the input boundary conditions are comprised of LOX facility heat loads, drain flow rates, recirculation flow rates and dewar heating. All the quantities are prescribed as functions of time. The first two test cases considered sensitivity of results to the computational grid. In Case 3, system heat load was changed, while in Case 4, a lower LOX level was specified. Cases 1 and 2 showed that the temperatures were not sensitive to the grid refinement. This provided a basic check on the numerical model. Cases 3 and 4 showed that the thermal boundary layer motion near the tank surface becomes more significant at the late time, e.g., 5 1/2 hours from replenish start. Comparison between results of Cases 3 and 4 showed, as expected, that the smaller initial LOX volume given in Case 4, results in higher temperature level. All calculated velocity and temperature distributions were found to be plausible

    Rocket injector anomalies study. Volume 1: Description of the mathematical model and solution procedure

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    The capability of simulating three dimensional two phase reactive flows with combustion in the liquid fuelled rocket engines is demonstrated. This was accomplished by modifying an existing three dimensional computer program (REFLAN3D) with Eulerian Lagrangian approach to simulate two phase spray flow, evaporation and combustion. The modified code is referred as REFLAN3D-SPRAY. The mathematical formulation of the fluid flow, heat transfer, combustion and two phase flow interaction of the numerical solution procedure, boundary conditions and their treatment are described

    Infrared horizon sensor modeling for attitude determination and control: Analysis and mission experience

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    The work performed by the Attitude Determination and Control Section at the National Aeronautics and Space Administration/Goddard Space Flight Center in analyzing and evaluating the performance of infrared horizon sensors is presented. The results of studies performed during the 1960s are reviewed; several models for generating the Earth's infrared radiance profiles are presented; and the Horizon Radiance Modeling Utility, the software used to model the horizon sensor optics and electronics processing to computer radiance-dependent attitude errors, is briefly discussed. Also provided is mission experience from 12 spaceflight missions spanning the period from 1973 to 1984 and using a variety of horizon sensing hardware. Recommendations are presented for future directions for the infrared horizon sensing technology

    Deubiquitylating enzymes and disease

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    Deubiquitylating enzymes (DUBs) can hydrolyze a peptide, amide, ester or thiolester bond at the C-terminus of UBIQ (ubiquitin), including the post-translationally formed branched peptide bonds in mono- or multi-ubiquitylated conjugates. DUBs thus have the potential to regulate any UBIQ-mediated cellular process, the two best characterized being proteolysis and protein trafficking. Mammals contain some 80–90 DUBs in five different subfamilies, only a handful of which have been characterized with respect to the proteins that they interact with and deubiquitylate. Several other DUBs have been implicated in various disease processes in which they are changed by mutation, have altered expression levels, and/or form part of regulatory complexes. Specific examples of DUB involvement in various diseases are presented. While no specific drugs targeting DUBs have yet been described, sufficient functional and structural information has accumulated in some cases to allow their rapid development

    Analysis of physical-chemical processes governing SSME internal fluid flows

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    The efforts to adapt CHAM's computational fluid dynamics code, PHOENICS, to the analysis of flow within the high pressure fuel turbopump (HPFTP) aft-platform seal cavity of the SSME are summarized. In particular, the special purpose PHOENICS satellite and ground station specifically formulated for this application are listed and described, and the preliminary results of the first part two-dimensional analyses are presented and discussed. Planned three-dimensional analyses are also briefly outlined. To further understand the mixing and combustion processes in the SSME fuelside preburners, a single oxygen-hydrogen jet element was investigated

    An observational study to evaluate the efficacy Pachana Poorvaka Shodhana i.e. Agnilepa Chikitsa followed by Virechana Karma in the management of Amavata w.s.r. to Rheumatoid Arthritis

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    The change in life style, food habits have contributed to a number of new diseases which have become a challenge for the human race, one among such diseases is Rheumatoid arthritis which is the commonest joint disorder. It is a systemic inflammatory disease of undetermined aetiology involving primarily the synovial membrane and articular structures of multiple joint. The disease is often progressive and result in pain, stiffness and swelling of joint. In India the prevalence rate is 0.1-0.4%. The symptoms of Rheumatoid arthritis are parallel with Amavata, as the name suggests Amavata is comprise of two terms, Ama and Vata. The Nidanas such as Viruddhaahara, Viruddhacheshta, Mandagni, Nischalatva etc. due to consumption of Viruddahara and indulging in Viruddhacheshta the Ama will be manifested. The manifested ama is carried by vata and circulates throughout the body and takes ashraya in Sandhis. Commonly affecting the joints of Hasta, Pada, Shira, Gulpha, Trika, Janu and Uru and characterized by pain similar to vrischika damshtra. In this present clinical trial, 10 diagnosed patients of Amavata / Rheumatoid arthritis were selected randomly to evaluate the efficacy of Pachana Poorvaka Shodhana that is Agnilepa Chikitsa followed by Virechana Karma in Amavata w.s.r. to Rheumatoid Arthritis. Statistical analysis showed highly significant results p value (<0.0001) in almost all subjective and objective parameters of Amavata

    Production Allocation Remodeling System: Optimizing for Competitive Advantage in a Mature Manufacturing Industry

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    Computational Simulation of the Formation and Material Behavior of Ice

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    Computational methods are described for simulating the formation and the material behavior of ice in prevailing transient environments. The methodology developed at the NASA Lewis Research Center was adopted. A three dimensional finite-element heat transfer analyzer was used to predict the thickness of ice formed under prevailing environmental conditions. A multi-factor interaction model for simulating the material behavior of time-variant ice layers is presented. The model, used in conjunction with laminated composite mechanics, updates the material properties of an ice block as its thickness increases with time. A sample case of ice formation in a body of water was used to demonstrate the methodology. The results showed that the formation and the material behavior of ice can be computationally simulated using the available composites technology
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