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The Theory of Capitalistic Stagnation

Description: The problem to be dealt with in this paper is the theory of capitalistic stagnation. Why is it important to examine the theory of capitalistic stagnation? The continuity of the theory of stagnation is the only portion of economic doctrine that is held in common by the Classical, Marxian, Keynesian, and Institutional economists.
Date: 1950
Creator: George, John E.
Partner: UNT Libraries

Liquefaction of air in the Langley 11-inch hypersonic tunnel

Description: Report presenting pressure and scattered-light measurements in the 11-inch hypersonic tunnel to determine the effect of stagnation temperature on the flow in two Mach number 7 nozzles and to determine the nature of the condensation process occurring at low stagnation temperatures. Results regarding the static-pressure measurements, Mach number effect, particle size and concentration, and general discussion are provided.
Date: October 1954
Creator: McLellan, Charles H. & Williams, Thomas W.
Partner: UNT Libraries Government Documents Department

Stagnation Temperature Recording

Description: "The present report deals with the development of a thermometer for recording stagnation temperature in compressible mediums in turbulent flow within 1 to 2 percent error of the adiabatic temperature in the stagnation point, depending upon the speed. This was achieved by placing the junction of a thermocouple near the stagnation point of an aerodynamically beneficial body, special care being taken to assure an uninterrupted supply of fresh compressed air on the junction together with the use of metals of low thermal conductivity, thus keeping heat-transfer and heat-dissipation losses to a minimum. In other experiments the use of the plate thermometer was proved unsuitable for practical measurements by reason of its profound influence in the reading by the Reynolds number and by the direction of flow" (p. 1).
Date: January 1941
Creator: Wimmer, W.
Partner: UNT Libraries Government Documents Department

Exploratory materials and missile-nose-shape tests in a 4,000 degrees F supersonic air jet

Description: Report presenting some exploratory materials and nose-shape tests in a small supersonic air jet with a stagnation temperature of approximately 4000 degrees Fahrenheit. Materials considered included graphite, copper, carbon steel, and stainless steel, and the nose shapes included 90 degree total-angle cones, hemispherical-face cylinders, and flat-face cylinders. The aerodynamic heat transfer to flat-face cylinders is appreciably less than to hemispherical-face cylinders.
Date: December 13, 1956
Creator: Purser, Paul E. & Hopko, Russell N.
Partner: UNT Libraries Government Documents Department

A Theoretical Study of Stagnation-Point Ablation

Description: "A simplified analysis is made of the shielding mechanism which reduces the stagnation-point heat trasnfer when ablation takes place at the surface. The ablation process considered is that in which the material changes directly from the solid to the gaseous state. The automatic shielding mechanism is discussed and the significant thermal properties of a good ablation material are given. The results of the analysis are given in terms of dimensionless parameters" (p. 1).
Date: September 1958
Creator: Roberts, Leonard
Partner: UNT Libraries Government Documents Department

Stability of Laminar Boundary Layer Near a Stagnation Point Over an Impermeable Wall and a Wall Cooled by Normal Fluid Injection

Description: Note presenting a theoretical determination of minimum critical Reynolds numbers for laminar instability of two-dimensional stagnation flows over a wall cooled by normal fluid injection. The individual and net effects of wall temperature and normal fluid injection on the stability characteristics of the laminar boundary layer are investigated.
Date: August 1957
Creator: Morduchow, Morris; Grape, Richard G. & Shaw, Richard P.
Partner: UNT Libraries Government Documents Department

Collapsing Bubble in Metal for High Energy Density Physics Study

Description: This paper presents a new idea to produce matter in the high energy density physics (HEDP) regime in the laboratory using an intense ion beam. A gas bubble created inside a solid metal may collapse by driving it with an intense ion beam. The melted metal will compress the gas bubble and supply extra energy to it. Simulations show that the spherical implosion ratio can be about 5 and at the stagnation point, the maximum density, temperature and pressure inside the gas bubble can go up to nearly 2 times solid density, 10 eV and a few megabar (Mbar) respectively. The proposed experiment is the first to permit access into the Mbar regime with existing or near-term ion facilities, and opens up possibilities for new physics gained through careful comparisons of simulations with measurements of quantities like stagnation radius, peak temperature and peak pressure at the metal wall.
Date: April 13, 2011
Creator: Ng, S F; Barnard, J J; Leung, P T & Yu, S S
Partner: UNT Libraries Government Documents Department

NOAA/Air Resources Laboratory ATLAS No. 1

Description: This is a report on air stagnation climatology for the United States (1948-1998). The report looks at the increase of urbanization and the air pollution problem that continues to rise.
Date: April 1999
Creator: Wang, Julian X. L. & Angell, James K.
Partner: UNT Libraries Government Documents Department

EROSION PREDICTION NEAR A STAGNATION POINT RESULTING FROM AERODYNAMICALLY ENTRAINED SOLID PARTICLES

Description: An analytic solution is obtained for the inviscid flow of a two-phase gas-solid mixture near a stagnation point. For this type of flow the momentum equilibration parameter, which is a measure of a particle's momentum, is found to be the unique determinant of particle trajectories. It is shown that values of this parameter less than one-fourth identify particles which never impact with a boundary. The closed-form solution is applied to an erosion model to predict the relative erosion distribution along the boundary. The erosion rate is found to be proportional to the particle velocity raised to the exponent of 4.0.
Date: June 1, 1979
Creator: Laitone, J. A.
Partner: UNT Libraries Government Documents Department

EROSION PREDICTION NEAR A STAGNATION POINT RESULTING FROM ENVIRONMENTAL SOLID PARTICLES

Description: Predicting the erosion that results from a gas-solid particle flow in coal energy conversion systems is crucial for the successful operation of coal gasification, magnetohydrodynamic power, and coal-fired turbine facilities. In this study the coupled gas-particle momentum equations are analytically solved to determine the particle trajectories near a plane stagnation point. The momentum equilibration parameter, which is a physical parameter measuring a particle's momentum, is found to be the unique criterion for predicting particle trajectories. It is shown that values of this parameter less than one-fourth identify particles that never impact with a wall. The closed-form solution obtained is used to predict the quantity of material removed from a wall as well as the location of erosion along the wall. The maximum erosion is calculated to occur for the momentum equilibration parameter taking a value of 2.3. The erosion rate is found to be proportional to the particle velocity raised to the exponent of 3.8.
Date: November 1, 1977
Creator: Laitone, J.
Partner: UNT Libraries Government Documents Department

Graded-density Reservoirs for Accessing High Pressure Low Temperature Material States

Description: In recently developed laser-driven shockless compression experiments an ablatively driven shock in a primary target is transformed into a ramp compression wave in a secondary target via unloading followed by stagnation across an intermediate vacuum gap. Current limitations on the achievable peak pressures are limited by the ability of shaping the temporal profile of the ramp compression pulse. We report on new techniques using graded density reservoirs for shaping the loading profile and extending these techniques to high peak pressures.
Date: April 19, 2006
Creator: Smith, R; Lorenz, K T; Ho, D; Remington, B; Hamza, A; Rogers, J et al.
Partner: UNT Libraries Government Documents Department

Analysis of three sets of SWIW tracer-test data using a two-population complex fracture model for matrix diffusion and sorption

Description: A complex fracture model employing two populations for diffusion and sorption is proposed to analyze three representative single-well injection-withdrawal (SWIW) tracer tests from Forsmark and Laxemar, the two sites under investigation by the Swedish Nuclear Fuel and Waste Management Company (SKB). One population represents the semi-infinite rock matrix and the other represents finite blocks that can become saturated, thereafter accepting no further diffusion or sorption. The diffusion and sorption parameters of the models are inferred by matching tracer breakthrough curves (BTCs). Three tracers are simultaneously injected, uranine (Ur), which is conservative, and rubidium (Rb) and cesium (Cs), which are non-conservative. For non-sorbing tracer uranine, the finite blocks become saturated with test duration of the order of 10 hours, and both the finite and the semi-infinite populations play a distinct role in controlling BTCs. For sorbing tracers Rb and Cs, finite blocks do not saturate, but act essentially as semi-infinite, and thus BTC behavior is comparable to that obtained for a model containing only a semi-infinite rock matrix. The ability to obtain good matches to BTCs for both sorbing and non-sorbing tracers for these three different SWIW data sets demonstrates that the two-population complex fracture model may be a useful conceptual model to analyze all SWIW tracer tests in fractured rock, and perhaps also usual multiwell tracer tests. One of the two populations should be semi-infinite rock matrix and the other finite blocks that can saturate. The latter can represent either rock blocks or gouge within the fracture, a fracture skin zone, or stagnation zones.
Date: August 1, 2009
Creator: Doughty, C. & Tsang, C.F.
Partner: UNT Libraries Government Documents Department

A Study of the Effectiveness of Four Competing Scenarios in Explaining the Causes of Stagflation

Description: This study investigates the relationship between stagflation and price stability and full employment and four economic scenarios and the economic condition. The data used in the study were obtained from government publications and were analyzed using hierarchical multiple regression. The standard inferential apparatus were employed. Give independent variables were found to be significant in explaining the causes of stagflation. These were: absolute change in M1, oil embargo of 1974, corporate profits, output per hour, and Iranian crisis of 1979. In conclusion, the causes of economic instability do not rest with one single theory or factor, but a combination of several.
Date: August 1983
Creator: Hurlbut, Toni T. (Toni Thompson)
Partner: UNT Libraries

Stability of spheromaks compressed by liquid walls

Description: We consider Rayleigh-Taylor instability of the liquid-plasma interface of a spheromak ignited by slow compression discussed previously. We conclude that instability may indeed occur despite the stabilizing influence of magnetic shear in the spheromak. If it occurs, instability would be greatest for modes concentrated toward the midplane. As for the cylindrical LINUS configuration, rotation about the geometric axis would stabilize these modes, but at the price of roughly doubling the input energy and reducing the gain. However, even in the absence of rotation, in a sphere instability occurs only at the end of compression near the stagnation point. Revised estimates of the fusion energy gain taking this brief period of instability into account still give, within the uncertainties, a gain G {approx} 20 for our earlier example with an input energy of 150 MJ and fusion yield of 3 GJ.
Date: August 17, 1999
Creator: Fowler, T K
Partner: UNT Libraries Government Documents Department

Acceleration and deceleration phase nonlinear Rayleigh-Taylor growth at spherical interfaces

Description: The Layzer model for the nonlinear evolution of bubbles in the Rayleigh-Taylor instability has recently been generalized to the case of spherically imploding interfaces [D. S. Clark and M. Tabak, to appear, PRE (2005).]. The spherical case is more relevant to, e.g., inertial confinement fusion or various astrophysical phenomena when the convergence is strong or the perturbation wavelength is comparable to the interface curvature. Here, the model is further extended to the case of bubble growth during the deceleration (stagnation) phase of a spherical implosion and to the growth of spikes during both the acceleration and deceleration phases. Differences in the nonlinear growth rates for both bubbles and spikes are found when compared with planar results. The model predictions are verified by comparison with numerical hydrodynamics simulations.
Date: April 8, 2005
Creator: Clark, D S & Tabak, M
Partner: UNT Libraries Government Documents Department

Complete equation of state for [beta]-HMX and implications for initiation

Description: A thermodynamically consistent equation of state for {beta}-HMX, the stable ambient polymorph of HMX, is developed that fits isothermal compression data and the temperature dependence of the specific heat computed from molecular dynamics. The equation of state is used to assess hot-spot conditions that would result from hydrodynamic pore collapse in a shock-to-detonation transition. The hot-spot temperature is determined as a function of shock strength by solving two Riemann problems in sequence: first for the velocity and density of the jet formed when the shock overtakes the pore, and second for the stagnation state when the jet impacts the far side of the pore. For a shock pressure below 5 GPa, the stagnation temperature from the jet is below the melt temperature at ambient pressure and hence insufficient for rapid reaction. Consequently for weak shocks a dissipation mechanism in addition to shock heating is needed to generate hot spots. When the stagnation temperature is sufficiently high for rapid reaction, the shock emanating from the hot spot is computed, assuming aconstant volume burn. For initial shocks below 20 GPa, the temperature behind the second shock is below 1000K and would not propagate a detonation wave. This analysis, based solely on the equation of state of the explosive, can serve as a check on mesoscale simulations of initiation in a plastic-bonded explosive.
Date: January 1, 2003
Creator: Sewell, T. D. (Thomas D.) & Menikoff, Ralph
Partner: UNT Libraries Government Documents Department

Development and testing of a photometric method to identify non-operating solar hot water systems in field settings.

Description: This report presents the results of experimental tests of a concept for using infrared (IR) photos to identify non-operational systems based on their glazing temperatures; operating systems have lower glazing temperatures than those in stagnation. In recent years thousands of new solar hot water (SHW) systems have been installed in some utility districts. As these numbers increase, concern is growing about the systems dependability because installation rebates are often based on the assumption that all of the SHW systems will perform flawlessly for a 20-year period. If SHW systems routinely fail prematurely, then the utilities will have overpaid for grid-energy reduction performance that is unrealized. Moreover, utilities are responsible for replacing energy for loads that failed SHW system were supplying. Thus, utilities are seeking data to quantify the reliability of SHW systems. The work described herein is intended to help meet this need. The details of the experiment are presented, including a description of the SHW collectors that were examined, the testbed that was used to control the system and record data, the IR camera that was employed, and the conditions in which testing was completed. The details of the associated analysis are presented, including direct examination of the video records of operational and stagnant collectors, as well as the development of a model to predict glazing temperatures and an analysis of temporal intermittency of the images, both of which are critical to properly adjusting the IR camera for optimal performance. Many IR images and a video are presented to show the contrast between operating and stagnant collectors. The major conclusion is that the technique has potential to be applied by using an aircraft fitted with an IR camera that can fly over an area with installed SHW systems, thus recording the images. Subsequent analysis of the images can determine ...
Date: June 1, 2012
Creator: He, Hongbo (University of New Mexico, Albuquerque, NM); Vorobieff, Peter V. (University of New Mexico, Albuquerque, NM); Menicucci, David (University of New Mexico, Albuquerque, NM); Mammoli, Andrea A. (University of New Mexico, Albuquerque, NM) & Carlson, Jeffrey J.
Partner: UNT Libraries Government Documents Department

Extinction Limits of Nonadiabatic, Catalyst-Assisted Flames in Stagnation-Point Flow

Description: An idealized geometry corresponding to a premixed flame in stagnation-point flow is used to investigate the effects of catalysis on extending the extinction limits of on adiabatic stretched flames. Specifically, a surface catalytic reaction is assumed to occur on the stagnation plane, thereby augmenting combustion in the bulk gas with a exothermic surface reaction characterized by a reduced activation energy. Assuming the activation energies remain large, an asymptotic analysis of the resulting flame structure yields a formula for the extinction limit as a function of various parameters. In particular, it is demonstrated that the presence of a surface catalyst can extend the burning regime, thus counterbalancing the effects of heat loss and flame stretch that tend to shrink it. The analysis is relevant to small-volume combustors, where the increased surface-to-volume ratio can lead to extinction of the nonadiabatic flame in the absence of a catalyst.
Date: February 1, 2001
Creator: Margolis, Stephen B. & Gardner, Timothy J.
Partner: UNT Libraries Government Documents Department

Extinction and Autoignition of n-Heptane in Counterflow Configuration

Description: A study is performed to elucidate the mechanisms of extinction and autoignition of n-heptane in strained laminar flows under nonpremixed conditions. A previously developed detailed mechanism made UP of 2540 reversible elementary reactions among 557 species is the starting point for the study. The detailed mechanism was previously used to calculate ignition delay times in homogeneous reactors, and concentration histories of a number of species in plug-flow and jet-stirred reactors. An intermediate mechanism made up of 1282 reversible elementary reactions among 282 species and a short mechanism made up of 770 reversible elementary reactions among 160 species are assembled from this detailed mechanism. Ignition delay times in an isochoric homogeneous reactor calculated using the intermediate and the short mechanism are found to agree well with those calculated using the detailed mechanism. The intermediate and the short mechanism are used to calculate extinction and autoignition of n-heptane in strained laminar flows. Steady laminar flow of two counter flowing Streams toward a stagnation plane is considered. One stream made up of prevaporized n-heptane and nitrogen is injected from the fuel boundary and the other stream made up of air and nitrogen is injected from the oxidizer boundary. Critical conditions of extinction and autoignition given by the strain rate, temperature and concentrations of the reactants at the boundaries, are calculated. The results are found to agree well with experiments. Sensitivity analysis is carried out to evaluate the influence of various elementary reactions on autoignition. At all values of the strain rate investigated here, high temperature chemical processes are found to control autoignition. In general, the influence of low temperature chemistry is found to increase with decreasing strain. A key finding of the present study is that strain has more influence on low temperature chemistry than the temperature of the reactants.
Date: January 12, 2000
Creator: Seiser, R.; Pitsch, H.; Seshadri, K.; Pitz, W.J. & Curran, H.J.
Partner: UNT Libraries Government Documents Department

Confined superadiabatic premixed flame-flow interaction

Description: Laminar premixed unity-Lewis number flames are studied numerically, to examine flow-flame interaction in a two-dimensional closed domain. Two opposed planar flame fronts are perturbed sinusoidally and allowed to develop by consuming premixed reactants. Combustion heat release leads to global pressure and temperature rise in the domain, due to confinement. A superadiabatic condition, with products temperature rising with distance behind the flame front, is observed due to stagnation pressure rise. Variations in tangential strain rate behind the perturbed flame fronts, due to flame curvature and heat release, result in a modified local superadiabatic temperature gradient in the products. These variations in temperature gradients are shown to determine the net local confinement-heating rate in the products, leading to corresponding deviations in products temperature, and the local reaction rate along the flame front. These observations, which are not consistent with one-dimensional superadiabatic stagnation flame behavior, are a direct result of the unrestrained unsteady nature of two-dimensional flame-flow interaction.
Date: December 1995
Creator: Najm, H. N.
Partner: UNT Libraries Government Documents Department

Stability of spheromaks compressed by liquid walls

Description: We consider Rayleigh-Taylor instability of the liquid-plasma interface of a spheromak ignited by slow compression discussed previously. We conclude that instability may indeed occur despite the stabilizing influence of magnetic shear in the spheromak. If it occurs, instability would be greatest for modes concentrated toward the midplane. As for the cylindrical LINUS configuration, rotation about the geometric axis would stabilize these modes, but at the price of roughly doubling the input energy and reducing the gain. However, even in the absence of rotation, in a sphere instability occurs only at the end of compression near the stagnation point. Revised estimates of the fusion energy gain taking this brief period of instability into account still give, within the uncertainties, a gain G {approx} 20 for our earlier example with an input energy of 150 MJ and fusion yield of 3 GJ.
Date: August 17, 1999
Creator: Fowler, T K
Partner: UNT Libraries Government Documents Department

Wire Initiation Studies at the University of Nevada-Reno: An LDRD Report

Description: Wire explosion experiments have been carried out at the University of Nevada, Reno. These experiments investigated the explosion phase of wires with properties and current-driving conditions comparable to that used in the initial stage of wire array z-pinch implosions on the Z machine at Sandia National Laboratories. Specifically, current pulses similar to and faster than the pre-pulse current on Z (current prior to fast rise in current pulse) were applied to single wire loads to study wire heating and the early development of plasmas in the wire initiation process. Understanding such issues are important to larger pulsed power machines that implode cylindrical wire array loads comprised of many wires. It is thought that the topology of an array prior to its acceleration influences the implosion and final stagnation properties, and therefore may depend on the initiation phase of the wires. Single wires ranging from 4 to 40 pm in diameter and comprised of material ranging from AI to W were investigated. Several diagnostics were employed to determine wire current, voltage, total emitted-light energy and power, along with the wire expansion velocity throughout the explosion. In a number of cases, the explosion process was also observed with x-ray backlighting using x-pinches. The experimental data indicates that the characteristics of a wire explosion depend dramatically on the rate of rise of the current, on the diameter of the wire, and on the heat of vaporization of the wire material. In this report, these characteristics will be described in detail. Of particular interest is the result that a faster current rise produces a higher energy deposition into the wire prior to explosion. This result introduces a different means of increasing the efficiency of wire heating. In this case, the energy deposition along the wire and its subsequent expansion, is uniform compared to a ...
Date: November 1, 2001
Creator: DOUGLAS, MELISSA R. & BAUER, BRUNO
Partner: UNT Libraries Government Documents Department

An evaluation of James' empirical formulae for the determination of two-phase flow characteristics in geothermal wells

Description: One of the most economical and simple methods of determination of two-phase flow parameters in geothermal well testing is the so-called James' method [1, 2]. The method consists of the measurements of lip pressure (p), and the flow rate of water (w) by a conventional weir. The stagnation enthalpy (h{sub o}) is then determined from a plot showing h{sub o} versus w/p{sup 0.96} which is empirically determined by James [1,2]. The mass flow rate is then determined from the following empirical formula G = 11,400 p{sup 0.96}/h{sub o}{sup 1.102} where G is the total mass flow rate in lb{sub m},/sec-ft{sup 2}, p is the lip pressure in psia, and h{sub o} is the specific enthalpy in BTU/lb{sub m}. The above relation is empirically determined for discharge pressure up to 64 psia and pipe diameters up to 8 inches. For pipe diameters smaller than 0.2 inches, it has been suggested that the value of 11,400 be replaced by 12,800. In view of the widespread use of the James' method, it is important to assess its accuracy and range of applicability.
Date: January 1, 1978
Creator: Cheng, P. & Karmarkar, M.
Partner: UNT Libraries Government Documents Department

Two-phase fluid flow through nozzles and abrupt enlargements

Description: The behavior of a fluid undergoing a phase change from liquid to vapor while flowing through a duct is of interest to engineers in many practical situations. For the case of interest to us, geothermal hot water flowing through various channels (well bores, surface pipes, equipment, etc.) may reach its flash point and choke point under appropriate conditions. The proper design of energy conversion systems depends on the ability of the engineer to predict this behavior with an acceptable degree of accuracy. The present study was in part motivated by the task of designing the blow-down, two-phase fluid flow test facility at Brown University. In that facility, a refrigerant (dichlorotetrafluoroethane or R-114) is boosted to a selected stagnation state and allowed to flow through a nozzle orifice into a long straight tube. The operation relies on the fluid being choked at the inlet section, and under certain circumstances, at the downstream section as well. A simple schematic of the test section is shown. This paper treats the problem generically and analytically, making use of the basic laws of fluid mechanics and thermodynamics. Specific calculations have been performed using R-114 as the flowing medium. They attempt to identify and describe all possible flow conditions in and downstream of the nozzle for all possible stagnation conditions.
Date: October 1, 1983
Creator: Olia, H.; Maeder, P.F.; DiPippo, R. & Dickinson, D.A.
Partner: UNT Libraries Government Documents Department