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Showing 1 to 20 of 25 for “"Polytropic"”.
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Application of an empirically-derived polytropic index for the solar wind to a solar wind shock propagation model
… used to determine an empirical value for the polytropic index for the free-streaming solar wind. Application of this non-adiabatic polytropic index to a two-dimensional solar wind computer model to simulate the effects of thermal heat conduction has been investigated. The current project …
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Development of an engine model for an integrated aircraft design tool
… model and High Pressure Compressor (HPC) polytropic efficiency correction for the propulsion module in the Transport Aircraft OPTtimization (TASOPT) code. The goal of this work is to improve the accuracy and applicability of TASOPT in conceptual design of advanced technology, high bypass …
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3D plume modeling of SPT-100
… the plasma potential. First, Boltzmann and polytropic models are used for electric potential calculations. Current density values obtained from both electron models are compared with previous experimental measurements and simulations in the literature. It was seen that the polytropic model …
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Estimation of the In-Cylinder Air/Fuel Ratio of an Internal Combustion Engine by the Use of Pressure Sensors
… phase of the compression stroke to a polytropic curve. The first method assumes a known polytropic exponent, and the other estimates the polytropic exponent. The first method results in a linear least-squares problem, and the second method results in a nonlinear least-squares problem. …
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A multidisciplinary algorithm for the 3-D design optimization of transonic axial compressor blades
… for the two designs were mass flow rate and polytropic efficiency respectively. Results for the Sanger rotor effort yielded an 8.1 % improvement in mass flow rate, a 5% improvement in total pressure ratio, and a 0.9 % increase in adiabatic efficiency. Application to the NASA Fan resulted in a …
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Neutron Star Models in Alternative Theories of Gravity
… for a set of equations of state, including a polytropic model and more realistic equations of state motivated by nuclear physics. Observable quantities such as masses, radii, etc are calculated for a set of parameters of the theories.</p><p>Specifically for Scalar-Tensor theories, we also …
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A study in spherical accretion of self-gravitating fluids in a general relativistic framework
… solved numerically for the most simple case of a polytropic fluid and compared to analytical solutions, which the model approximates in the "test-fluid" limit. The model is then focused on the accretion of a relativistic Fermi gas and the implications this might have on the rapid growth of …
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Performance Attributes and Research Facility Design for 1KW High-speed Small Gas Turbine Engine
… increase in compressor pressure ratio and polytropic efficiency or by incorporating a high performance recuperator. The compressor polytropic efficiency is improvable by 3 to 6 percentage points through effective clearance management. Previous experiments on the test engine demonstrated the …
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Gravity wave signals from relativistic calculations of binary neutron star coalescence
… binary systems, for neutron stars with polytropic equations of state, finding that relativistic corrections play an important role in the dynamical stability of such sytems and the resulting gravitational wave forms. Relativistic corrections also suppress mass shedding in these systems. …
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Instrument development and plasma measurements on a 200-watt Hall thruster plume
… vary substantially across the plume following a polytropic relationship. These experimental results were compared to solutions of a self-similar plume model. Data analyses were also performed using a consistency analysis of the experimental data by deducing plasma potential from Faraday and cold …
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Present and early star formation : a study on rotational and thermal properties
… issue by studying the effects of a piecewise polytropic equation of state on the formation of stellar clusters. We increase the polytropic exponent γ from a value below unity to a value above unity at a certain critical density. The change of the thermodynamic state at the critical density …
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The development of a prototype external heat engine based on the Ericsson cycle
… designed to function off a cycle consisting of a polytropic compression, a polytropic expansion with heat addition and a constant volume heat rejection process, achieved using a two-stroke principal to exchange the hot exhaust gas with cold recharge gas. Based on experience gained from this model, …
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Shear instabilities in stellar objects: linear stability and non-linear evolution
… non-linear evolution in a fully compressible polytropic atmosphere provides a fundamental understanding of potential motion in stellar interiors and is the main focus of this thesis. To commence the investigations a linear stability analysis of a stratified system in a two-dimensional …
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Impact of efficiency-driven aircraft technology improvements on climate and air quality
… technologies — such as increased component polytropic efficiencies or higher allowable turbine-metal temperatures — can reduce fuel consumption by more than 10% under favorable re-optimizations of engine design. However, they often raise engine core pressures or temperatures in ways that …
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Small core axial compressors for high efficiency jet aircraft
… assessed computationally and a 1.6% decrease in polytropic efficiency is found for a 1% increase in gap-to-span ratio. At the above clearance, these efficiency penalties increase aircraft mission fuel burn by 3.4%, if current design guidelines are employed. This penalty, however, may be reduced …
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Leveraging numerical relativity formulations for perturbative analysis: applications to quasinormal modes in general relativity
… method, we analyze three models derived from a polytropic equation of state: one stable, one marginally stable near the onset of instability, and one unstable. Our results consistent with those derived from standard methods, confirming the expected stability characteristics of these models.
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Numerical Investigation of Subsonic Axial-Flow Tandem Airfoils for a Core Compressor Rotor
… by attaining a higher work coefficient, polytropic efficiency and numerical stall margin. An examination of the tandem rotor fluid mechanics revealed that the forward blade acts in a similar manner to a conventional rotor. The aft blade is strongly dependent upon the flow it receives from …
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A plethysmographic device for determining human body volume and body density
… consuming. An alternative method, based on a polytropic thermodynamic process, is described for body volume measurement and thereby for body composition assessment. Previous use of this method by Taylor, et al. (1985) and Gundlach and Visscher (1986) were successful, but complex in terms of …
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Validation of the DRACO Particle-in-Cell Code using Busek 200W Hall Thruster Experimental Data
… is performed by comparing the plasma potential, polytropic temperature, ion number density of the thruster plume as well as Faraday and ExB probe results. The study compares the newly developed HPHall source with older source models and also compares the variations of the HPHall source. The field …
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Development of the DRACO ES-PIC code and Fully-Kinetic Simulation of Ion Beam Neutralization
… Comparison were made between the Maxwellian and polytropic temperatures, as well as between simulation electron density and one predicted by the Boltzmann relationship. The cathode was modeled individually from the beam by introducing a positively charged collector plate at a distance …
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