Evaluation of water cooled supersonic temperature and pressure probes for application to 2000 F flows

NASA Technical Reports Server (NTRS)

Lagen, Nicholas T.; Seiner, John M.

1990-01-01

The development of water cooled supersonic probes used to study high temperature jet plumes is addressed. These probes are: total pressure, static pressure, and total temperature. The motivation for these experiments is the determination of high temperature supersonic jet mean flow properties. A 3.54 inch exit diameter water cooled nozzle was used in the tests. It is designed for exit Mach 2 at 2000 F exit total temperature. Tests were conducted using water cooled probes capable of operating in Mach 2 flow, up to 2000 F total temperature. Of the two designs tested, an annular cooling method was chosen as superior. Data at the jet exit planes, and along the jet centerline, were obtained for total temperatures of 900 F, 1500 F, and 2000 F, for each of the probes. The data obtained from the total and static pressure probes are consistent with prior low temperature results. However, the data obtained from the total temperature probe was affected by the water coolant. The total temperature probe was tested up to 2000 F with, and without, the cooling system turned on to better understand the heat transfer process at the thermocouple bead. The rate of heat transfer across the thermocouple bead was greater when the coolant was turned on than when the coolant was turned off. This accounted for the lower temperature measurement by the cooled probe. The velocity and Mach number at the exit plane and centerline locations were determined from the Rayleigh-Pitot tube formula.

Elusive anion growth in Titan's atmosphere: Low temperature kinetics of the C3N- + HC3N reaction

NASA Astrophysics Data System (ADS)

Bourgalais, Jérémy; Jamal-Eddine, Nour; Joalland, Baptiste; Capron, Michael; Balaganesh, Muthiah; Guillemin, Jean-Claude; Le Picard, Sébastien D.; Faure, Alexandre; Carles, Sophie; Biennier, Ludovic

2016-06-01

Ion chemistry appears to be deeply involved in the formation of heavy molecules in the upper atmosphere of Titan. These large species form the seeds of the organic aerosols responsible for the opaque haze surrounding the biggest satellite of Saturn. The chemical pathways involving individual anions remain however mostly unknown. The determination of the rates of the elementary reactions with ions and the identification of the products are essential to the progress in our understanding of Titan's upper atmosphere. We have taken steps in that direction through the investigation of the low temperature reactivity of C3N- , which was tentatively identified in the spectra measured by the CAPS-ELS instrument of the Cassini spacecraft during its high altitude flybys. The reaction of this anion with HC3N, one of the most abundant trace organics in the atmosphere, has been studied over the 49-294 K temperature range in uniform supersonic flows using the CRESU technique. The proton transfer is found to be the main exit channel (>91%) of the C315N- + HC3N reaction. It remains however indistinguishable with the non-isotopically labeled C314N- reactant. The T - 1 / 2 temperature dependence of this proton transfer reaction and its global rate are reasonably well reproduced theoretically using an average dipole orientation model. A minor exit channel, reactive detachment (< 9%), has also been uncovered, although the nature of the neutral products has not been determined. It is concluded that the C314N- + HC3N reaction cannot contribute to the growth of molecular anions in the upper atmosphere of Titan. Due to the low branching into the neutral exit channel, it cannot contribute either to the growth of neutrals even assuming a complete mass transfer.

Correction analysis for a supersonic water cooled total temperature probe tested to 1370 K

NASA Technical Reports Server (NTRS)

Lagen, Nicholas T.; Seiner, John M.

1991-01-01

The authors address the thermal analysis of a water cooled supersonic total temperature probe tested in a Mach 2 flow, up to 1366 K total temperature. The goal of this experiment was the determination of high-temperature supersonic jet mean flow temperatures. An 8.99 cm exit diameter water cooled nozzle was used in the tests. It was designed for exit Mach 2 at 1366 K exit total temperature. Data along the jet centerline were obtained for total temperatures of 755 K, 1089 K, and 1366 K. The data from the total temperature probe were affected by the water coolant. The probe was tested through a range of temperatures between 755 K and 1366 K with and without the cooling system turned on. The results were used to develop a relationship between the indicated thermocouple bead temperature and the freestream total temperature. The analysis and calculated temperatures are presented.

Influence of the cooling degree upon performances of internal combustion engine

NASA Astrophysics Data System (ADS)

Grǎdinariu, Andrei Cristian; Mihai, Ioan

2016-12-01

Up to present, air cooling systems still raise several unsolved problems due to conditions imposed by the environment in terms of temperature and pollution levels. The present paper investigates the impact of the engine cooling degree upon its performances, as important specific power is desired for as low as possible fuel consumption. A technical solution advanced by the authors[1], consists of constructing a bi-flux compressor, which can enhance the engine's performances. The bi-flux axial compressor accomplishes two major functions, that is it cools down the engine and it also turbocharges it. The present paper investigates the temperature changes corresponding to the fresh load, during the use of a bi-flux axial compressor. This compressor is economically simple, compact, and offers an optimal response at low rotational speeds of the engine, when two compression steps are used. The influence of the relative coefficient of air temperature drop upon working agent temperature at the intercooler exit is also investigated in the present work. The variation of the thermal load coefficient by report to the working agent temperature is also investigated during engine cooling. The variation of the average combustion temperature is analyzed in correlation to the thermal load coefficient and the temperatures of the working fluid at its exit from the cooling system. An exergetic analysis was conducted upon the influence of the cooling degree on the motor fluid and the gases resulted from the combustion process.

Exit Examinations, Peer Academic Climate, and Adolescents' Developmental Outcomes

ERIC Educational Resources Information Center

Benner, Aprile D.

2013-01-01

Implications of high school exit examination performance were examined with a sample of 672 racial/ethnic minority students. Exit examination failure in the 10th grade was negatively linked to subsequent grade point average, school engagement, and school belonging one year later, controlling for outcomes prior to taking the examination.…

Computer program for preliminary design analysis of axial-flow turbines

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1972-01-01

The program method is based on a mean-diameter flow analysis. Input design requirements include power or pressure ratio, flow, temperature, pressure, and speed. Turbine designs are generated for any specified number of stages and for any of three types of velocity diagrams (symmetrical, zero exit swirl, or impulse). Exit turning vanes can be included in the design. Program output includes inlet and exit annulus dimensions, exit temperature and pressure, total and static efficiencies, blading angles, and last-stage critical velocity ratios. The report presents the analysis method, a description of input and output with sample cases, and the program listing.

Analysis of Steady, Two-Dimensional Chemically Reacting Nonequilibrium Flow by an Unsteady, Asymptotically Consistent Technique. Volume I. Theoretical Development.

DTIC Science & Technology

1982-09-01

wall, and exit points are know,, collectively as boundary points. In the following discussion, thi numerical treatment used for each type of mesh point...and fiozen solutions and that it matches the ODK solution 6 [Reference (10)] quite well. Also note that in this case, there is only a small departure...shows the results of the H-F system analysis. The mass-averaged temperature profile falls between the equilibrium and frozen solutions and matches the ODK

29 CFR 1910.1003 - 13 Carcinogens (4-Nitrobiphenyl, etc.).

Code of Federal Regulations, 2012 CFR

2012-07-01

... the top and bottom, designed and maintained so as to draw air inward at an average linear face... to wash hands, forearms, face, and neck upon each exit from the regulated areas, close to the point..., face, and neck on each exit from the regulated area, close to the point of exit, and before engaging in...

29 CFR 1910.1003 - 13 Carcinogens (4-Nitrobiphenyl, etc.).

Code of Federal Regulations, 2013 CFR

2013-07-01

... the top and bottom, designed and maintained so as to draw air inward at an average linear face... to wash hands, forearms, face, and neck upon each exit from the regulated areas, close to the point..., face, and neck on each exit from the regulated area, close to the point of exit, and before engaging in...

29 CFR 1910.1003 - 13 Carcinogens (4-Nitrobiphenyl, etc.).

Code of Federal Regulations, 2014 CFR

2014-07-01

... the top and bottom, designed and maintained so as to draw air inward at an average linear face... to wash hands, forearms, face, and neck upon each exit from the regulated areas, close to the point..., face, and neck on each exit from the regulated area, close to the point of exit, and before engaging in...

Heat-induced symmetry breaking in ant (Hymenoptera: Formicidae) escape behavior

PubMed Central

Chung, Yuan-Kai

2017-01-01

The collective egress of social insects is important in dangerous situations such as natural disasters or enemy attacks. Some studies have described the phenomenon of symmetry breaking in ants, with two exits induced by a repellent. However, whether symmetry breaking occurs under high temperature conditions, which are a common abiotic stress, remains unknown. In our study, we deposited a group of Polyrhachis dives ants on a heated platform and counted the number of escaping ants with two identical exits. We discovered that ants asymmetrically escaped through two exits when the temperature of the heated platform was >32.75°C. The degree of asymmetry increased linearly with the temperature of the platform. Furthermore, the higher the temperature of heated platform was, the more ants escaped from the heated platform. However, the number of escaping ants decreased for 3 min when the temperature was higher than the critical thermal limit (39.46°C), which is the threshold for ants to endure high temperature without a loss of performance. Moreover, the ants tended to form small groups to escape from the thermal stress. A preparatory formation of ant grouping was observed before they reached the exit, indicating that the ants actively clustered rather than accidentally gathered at the exits to escape. We suggest that a combination of individual and grouping ants may help to optimize the likelihood of survival during evacuation. PMID:28355235

CHARGE MEASUREMENTS ON INDIVIDUAL PARTICLES EXITING LABORATORY PRECIPITATORS WITH POSITIVE AND NEGATIVE CORONA AT VARIOUS TEMPERATURES

EPA Science Inventory

The paper reports measurements of charge values on individual particles exiting three different laboratory electrostatic precipitators (ESPs) in an experimental apparatus containing a Millikan cell. Dioctylphthalate (DOP) droplets and fly ash particles were measured at temperatur...

Effect of Geometric Parameters on the Performance of Second Throat Annular Steam Ejectors

DTIC Science & Technology

1991-07-01

Cell Pressure versus Rake Average Exit Pitot Pressure . . . . . . . . . . . 42 15. Baseline Wall Pressure Profiles...diffuser exit plane pitot pressure rake . 2.5.2 Alternate Configurations Six alternate ejector diffuser configurations were tested. A summary of...along the walls of the diffusers to help characterize the flow. The ejector diffuser exit pitot pressure was measured with a 6-probe pitot pressure rake

PRELIMINARY DESIGN ANALYSIS OF AXIAL FLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

A computer program has been developed for the preliminary design analysis of axial-flow turbines. Rapid approximate generalized procedures requiring minimum input are used to provide turbine overall geometry and performance adequate for screening studies. The computations are based on mean-diameter flow properties and a stage-average velocity diagram. Gas properties are assumed constant throughout the turbine. For any given turbine, all stages, except the first, are specified to have the same shape velocity diagram. The first stage differs only in the value of inlet flow angle. The velocity diagram shape depends upon the stage work factor value and the specified type of velocity diagram. Velocity diagrams can be specified as symmetrical, zero exit swirl, or impulse; or by inputting stage swirl split. Exit turning vanes can be included in the design. The 1991 update includes a generalized velocity diagram, a more flexible meanline path, a reheat model, a radial component of velocity, and a computation of free-vortex hub and tip velocity diagrams. Also, a loss-coefficient calibration was performed to provide recommended values for airbreathing engine turbines. Input design requirements include power or pressure ratio, mass flow rate, inlet temperature and pressure, and rotative speed. The design variables include inlet and exit diameters, stator angle or exit radius ratio, and number of stages. Gas properties are input as gas constant, specific heat ratio, and viscosity. The program output includes inlet and exit annulus dimensions, exit temperature and pressure, total and static efficiencies, flow angles, blading angles, and last stage absolute and relative Mach numbers. This program is written in FORTRAN 77 and can be ported to any computer with a standard FORTRAN compiler which supports NAMELIST. It was originally developed on an IBM 7000 series computer running VM and has been implemented on IBM PC computers and compatibles running MS-DOS under Lahey FORTRAN, and DEC VAX series computers running VMS. Format statements in the code may need to be rewritten depending on your FORTRAN compiler. The source code and sample data are available on a 5.25 inch 360K MS-DOS format diskette. This program was developed in 1972 and was last updated in 1991. IBM and IBM PC are registered trademarks of International Business Machines. MS-DOS is a registered trademark of Microsoft Corporation. DEC VAX, and VMS are trademarks of Digital Equipment Corporation.

Thermal regime, predation danger and the early marine exit of sockeye salmon Oncorhynchus nerka.

PubMed

Katinic, P J; Patterson, D A; Ydenberg, R C

2015-01-01

Marine exit timing of sockeye salmon Oncorhynchus nerka populations on the Haida Gwaii Archipelago, British Columbia, Canada, is described, with specific focus on Copper Creek. Marine exit in Copper Creek occurs > 130 days prior to spawning, one of the longest adult freshwater residence periods recorded for any O. nerka population. Copper Creek presents an easy upstream migration, with mild water temperatures (7 to 14°  C), short distance (13·1 km) and low elevation gain (41 m) to the lake where fish hold prior to spawning. An energetic model estimates that <1% of the initial energy reserve is required for upstream migration, compared with 62% for lake holding and 38% for reproductive development. Historical records suggest that it is unlikely that water temperature in any of the O.nerka streams in Haida Gwaii has ever exceeded the presumed temperature threshold (19° C) for early marine exit. Although it is not impossible that the thermal tolerance of Copper Creek O.nerka is very low, the data presented here appear inconsistent with thermal avoidance as an explanation for the early marine exit timing in Copper Creek and in three other populations on the archipelago with early marine exit. © 2014 The Fisheries Society of the British Isles.

Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mena, Francisco; Bond, Tami C.; Riemer, Nicole

Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN) from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution) in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCNmore » activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs) or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 10 16 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation ( s sat). Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity) can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume processes. This homogenizing effect requires the components to be truly co-emitted, rather than sequentially emitted.« less

Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

NASA Astrophysics Data System (ADS)

Mena, Francisco; Bond, Tami C.; Riemer, Nicole

2017-08-01

Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN) from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution) in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCN activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs) or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 1016 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation (ssat). Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity) can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume processes. This homogenizing effect requires the components to be truly co-emitted, rather than sequentially emitted.

Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

DOE PAGES

Mena, Francisco; Bond, Tami C.; Riemer, Nicole

2017-08-07

Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN) from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution) in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCNmore » activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs) or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 10 16 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation ( s sat). Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity) can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume processes. This homogenizing effect requires the components to be truly co-emitted, rather than sequentially emitted.« less

DESIGN ANALYSIS OF RADIAL INFLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

Design study of an advanced gas generator. [which can be ignited during start-up period of turbine engines

NASA Technical Reports Server (NTRS)

Kim, S.; Trinh, H. P.

1993-01-01

A gas generator which can be ignited reliably during the initial start-up period and offers fairly uniform gas temperature at the exit was studied numerically. Various sizes and shapes of the mixing enhancement devices and their positions were examined to evaluate the uniformity of the exit gas temperature and the change of internal pressure drop incurred by introducing the mixing enhancement devices. By introducing a turbulence ring and a splash plate with an appropriate size and position, it was possible to obtain fairly uniform gas temperature distributions and a maximum gas temperature that is within the design limit temperature of 1600 R at the generator exit. However, with the geometry studied, the pressure drop across the generator was great, approximately 1150 psi, to satisfy the assigned design limit temperature. If the design limit temperature is increased to 1650 R, the pressure drop across the generator could be lowered by as much as 350 psi.

Measurements of temperature profiles at the exit of small rockets.

PubMed

Griggs, M; Harshbarger, F C

1966-02-01

The sodium line reversal technique was used to determine the reversal temperature profile across the exit of small rockets. Measurements were made on one 73-kg thrust rocket, and two 23-kg thrust rockets with different injectors. The large rocket showed little variation of reversal temperature across the plume. However, the 23-kg rockets both showed a large decrease of reversal temperature from the axis to the edge of the plume. In addition, the sodium line reversal technique of temperature measurement was compared with an infrared technique developed in these laboratories.

Convective heat transfer from a pulsating radial jet reattachment (PRJR) nozzle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, J.Y.; James, D.L.; Parameswaran, S.

1999-07-01

Impinging jets of fluid have been used to cool, heat or dry surfaces in many industries including high temperature gas turbines, paper and glass manufacturing, textile drying, and electronic components. Jets may be broadly classified as either inline or radial. Inline jets typically have some type of circular or planer opening through which the fluid exits. The circular opening may be converging, well rounded, or of the same diameter as the nozzle or tube through which the fluid is delivered. Here, a numerical investigation for air exiting a Pulsating Radial Jet Reattachment (PRJR) nozzle was performed with various flow andmore » geometric conditions. The transient ensemble averaged Navier-Stokes equation with the standard {kappa}-{epsilon} turbulence model and the standard transient turbulent energy equation were solved to predict the velocity, pressure, and temperature distributions as a function of the pulsation rate, nondimensionalized nozzle-to-plate spacing, amplitude ratio, exit angle and gap Reynolds number. Sinusoidal profile, square and triangular pulsation profiles were simulated to determine the effect on the convective heat transfer during pulsation of nozzle. Grid movement is coupled to the flow field in a manner by a grid convection. Calculated reattachment radii for various conditions correlated well with previously obtained experimental results. Calculated convective heat transfer coefficients and surface pressure profiles for various geometric and flow conditions were compared with experimental results. Convective heat transfer coefficient calculations matched the experimental values very well outside the reattachment regions and underpredicted the convective heat transfer data underneath the nozzle in the dead water region and on the reattachment radius.« less

Fluorescence Imaging of Rotational and Vibrational Temperature in a Shock Tunnel Nozzle Flow

NASA Technical Reports Server (NTRS)

Palma, Philip C.; Danehy, Paul M.; Houwing, A. F. P.

2003-01-01

Two-dimensional rotational and vibrational temperature measurements were made at the nozzle exit of a free-piston shock tunnel using planar laser-induced fluorescence. The Mach 7 flow consisted predominantly of nitrogen with a trace quantity of nitric oxide. Nitric oxide was employed as the probe species and was excited at 225 nm. Nonuniformities in the distribution of nitric oxide in the test gas were observed and were concluded to be due to contamination of the test gas by driver gas or cold test gas.The nozzle-exit rotational temperature was measured and is in reasonable agreement with computational modeling. Nonlinearities in the detection system were responsible for systematic errors in the measurements. The vibrational temperature was measured to be constant with distance from the nozzle exit, indicating it had frozen during the nozzle expansion.

Design assurance test of the Thiokol Te-M-521-5 apogee kick motor tested in the spin mode at simulated altitude conditions

NASA Technical Reports Server (NTRS)

Cimino, A. A.

1973-01-01

One Thiokol Chemical Corporation TE-M-521-5 solid-propellant apogee rocket motor was successfully fired at an average simulated altitude of about 108,000 ft while spinning at 46 rpm. The general program objectives were to verify compliance of motor performance with the manufacturer's specifications. Specific primary objectives were to determine vacuum ballistic performance of the motor after prefire vibration conditioning and temperature conditioning at 40F, altitude ignition characteristics, motor structural integrity, and motor temperature-time history during and after motor operation. Additional objectives were to measure the lateral (nonaxial) thrust component during motor operation and to measure radiation heat flux in the vicinity of the nozzle exit plane.

Temperature and pressure measurements at cold exit of counter-flow vortex tube with flow visualization of reversed flow

NASA Astrophysics Data System (ADS)

Yusof, Mohd Hazwan bin; Katanoda, Hiroshi; Morita, Hiromitsu

2015-02-01

In order to clarify the structure of the cold flow discharged from the counter-flow vortex tube (VT), the temperature and pressure of the cold flow were measured, and the existence and behavior of the reversed flow at the cold exit was studied using a simple flow visualization technique consisting of a 0.75mm-diameter needle, and an oil paint droplet. It is observed through this experiment that the Pitot pressure at the cold exit center can either be lower or higher than atmospheric pressure, depending on the inlet pressure and the cold fraction, and that a reversed flow is observed when the Pitot pressure at the cold exit center is lower than atmospheric pressure. In addition, it is observed that when reducing the cold fraction from unity at any arbitrary inlet pressure, the region of reversed and colder flow in the central part of cold exit extends in the downstream direction.

The effect of nozzle-exit-channel shape on resultant fiber diameter in melt-electrospinning

NASA Astrophysics Data System (ADS)

Esmaeilirad, Ahmad; Ko, Junghyuk; Rukosuyev, Maxym V.; Lee, Jason K.; Lee, Patrick C.; Jun, Martin B. G.

2017-01-01

In recent decades, electrospinning using a molten poly (ε-caprolactone) resin has gained attention for creating fibrous tissue scaffolds. The topography and diameter control of such electrospun microfibers is an important issue for their different applications in tissue engineering. Charge density, initial nozzle-exit-channel cross-sectional area, nozzle to collector distance, viscosity, and processing temperature are the most important input parameters that affect the final electrospun fiber diameters. In this paper we will show that the effect of nozzle-exit-channel shape is as important as the other effective parameters in a resultant fiber diameter. However, to the best of our knowledge, the effect of nozzle-exit-channel shapes on a resultant fiber diameter have not been studied before. Comparing rectangular and circular nozzles with almost the same exit-channel cross-sectional areas in a similar processing condition showed that using a rectangular nozzle resulted in decreasing final fiber diameter up to 50%. Furthermore, the effect of processing temperature on the final fiber topography was investigated.

Uncertainty of calorimeter measurements at NREL's high flux solar furnace

NASA Astrophysics Data System (ADS)

Bingham, C. E.

1991-12-01

The uncertainties of the calorimeter and concentration measurements at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL) are discussed. Two calorimeter types have been used to date. One is an array of seven commercially available circular foil calorimeters (gardon or heat flux gages) for primary concentrator peak flux (up to 250 W/sq cm). The second is a cold-water calorimeter designed and built by the University of Chicago to measure the average exit power of the reflective compound parabolic secondary concentrator used at the HFSF (over 3.3 kW across a 1.6/sq cm) exit aperture, corresponding to a flux of about 2 kW/sq cm. This paper discussed the uncertainties of the calorimeter and pyrheliometer measurements and resulting concentration calculations. The measurement uncertainty analysis is performed according to the ASME/ANSI standard PTC 19.1 (1985). Random and bias errors for each portion of the measurement are analyzed. The results show that as either the power or the flux is reduced, the uncertainties increase. Another calorimeter is being designed for a new, refractive secondary which will use a refractive material to produce a higher average flux (5 kW/sq cm) than the reflective secondary. The new calorimeter will use a time derivative of the fluid temperature as a key measurement of the average power out of the secondary. A description of this calorimeter and test procedure is also presented, along with a pre-test estimate of major sources of uncertainty.

Evaluation of Federal Aviation Administration Engine Exhaust Sampling Rake.

DTIC Science & Technology

1977-06-01

Engine exit total pressure - Pt7 " High turbine discharge temperature - Tt65,6 . Engine exit total temperature - Tt7 - Burner pressure - Ps4 0 Total...illustrated by Figure 22, a plot of Ps4 /Pt7 (expansion thru the turbine) vs. EPR (Pt7/Pt2). This plot indicates that the ECCP rake has no measurable effect on

Transgenic C. elegans dauer larvae expressing hookworm phospho null DAF-16/FoxO exit dauer.

PubMed

Gelmedin, Verena; Brodigan, Thomas; Gao, Xin; Krause, Michael; Wang, Zhu; Hawdon, John M

2011-01-01

Parasitic hookworms and the free-living model nematode Caenorhabtidis elegans share a developmental arrested stage, called the dauer stage in C. elegans and the infective third-stage larva (L3) in hookworms. One of the key transcription factors that regulate entrance to and exit from developmental arrest is the forkhead transcription factor DAF-16/FoxO. During the dauer stage, DAF-16 is activated and localized in the nucleus. DAF-16 is negatively regulated by phosphorylation by the upstream kinase AKT, which causes DAF-16 to localize out of the nucleus and the worm to exit from dauer. DAF-16 is conserved in hookworms, and hypothesized to control recovery from L3 arrest during infection. Lacking reverse genetic techniques for use in hookworms, we used C. elegans complementation assays to investigate the function of Ancylostoma caninum DAF-16 during entrance and exit from L3 developmental arrest. We performed dauer switching assays and observed the restoration of the dauer phenotype when Ac-DAF-16 was expressed in temperature-sensitive dauer defective C. elegans daf-2(e1370);daf-16(mu86) mutants. AKT phosphorylation site mutants of Ac-DAF-16 were also able to restore the dauer phenotype, but surprisingly allowed dauer exit when temperatures were lowered. We used fluorescence microscopy to localize DAF-16 during dauer and exit from dauer in C. elegans DAF-16 mutant worms expressing Ac-DAF-16, and found that Ac-DAF-16 exited the nucleus during dauer exit. Surprisingly, Ac-DAF-16 with mutated AKT phosphorylation sites also exited the nucleus during dauer exit. Our results suggest that another mechanism may be involved in the regulation DAF-16 nuclear localization during recovery from developmental arrest.

Effects of inlet distortion on gas turbine combustion chamber exit temperature profiles

NASA Astrophysics Data System (ADS)

Maqsood, Omar Shahzada

Damage to a nozzle guide vane or blade, caused by non-uniform temperature distributions at the combustion chamber exit, is deleterious to turbine performance and can lead to expensive and time consuming overhaul and repair. A test rig was designed and constructed for the Allison 250-C20B combustion chamber to investigate the effects of inlet air distortion on the combustion chamber's exit temperature fields. The rig made use of the engine's diffuser tubes, combustion case, combustion liner, and first stage nozzle guide vane shield. Rig operating conditions simulated engine cruise conditions, matching the quasi-non-dimensional Mach number, equivalence ratio and Sauter mean diameter. The combustion chamber was tested with an even distribution of inlet air and a 4% difference in airflow at either side. An even distribution of inlet air to the combustion chamber did not create a uniform temperature profile and varying the inlet distribution of air exacerbated the profile's non-uniformity. The design of the combustion liner promoted the formation of an oval-shaped toroidal vortex inside the chamber, creating localized hot and cool sections separated by 90° that appeared in the exhaust. Uneven inlet air distributions skewed the oval vortex, increasing the temperature of the hot section nearest the side with the most mass flow rate and decreasing the temperature of the hot section on the opposite side. Keywords: Allison 250, Combustion, Dual-Entry, Exit Temperature Profile, Gas Turbine, Pattern Factor, Reverse Flow.

Exiting and Returning to the Parental Home for Boomerang Kids

PubMed Central

Sandberg-Thoma, Sara E.; Snyder, Anastasia R.; Jang, Bohyun Joy

2015-01-01

Young adults commonly exit from and return to the parental home, yet few studies have examined the motivation behind these exits and returns using a life course framework. Using data from the National Longitudinal Survey of Youth 1997, the authors examined associations between mental health problems and economic characteristics and exits from (n = 8,162), and returns to (n = 6,530), the parental home during the transition to adulthood. The average age of the respondents was 24 years. The authors found evidence that mental health and economic characteristics were related to home leaving and returning. Emotional distress was associated with earlier exits from, and returns to, the parental home; alcohol problems were associated with earlier returns to the parental home. The findings regarding economic resources were unexpectedly mixed. Greater economic resources were linked to delayed exits from, and earlier returns to, the parental home. The implications of these findings for young adults are discussed. PMID:26023244

Exiting and Returning to the Parental Home for Boomerang Kids.

PubMed

Sandberg-Thoma, Sara E; Snyder, Anastasia R; Jang, Bohyun Joy

2015-06-01

Young adults commonly exit from and return to the parental home, yet few studies have examined the motivation behind these exits and returns using a life course framework. Using data from the National Longitudinal Survey of Youth 1997, the authors examined associations between mental health problems and economic characteristics and exits from (n = 8,162), and returns to (n = 6,530), the parental home during the transition to adulthood. The average age of the respondents was 24 years. The authors found evidence that mental health and economic characteristics were related to home leaving and returning. Emotional distress was associated with earlier exits from, and returns to, the parental home; alcohol problems were associated with earlier returns to the parental home. The findings regarding economic resources were unexpectedly mixed. Greater economic resources were linked to delayed exits from, and earlier returns to, the parental home. The implications of these findings for young adults are discussed.

Theoretical Rocket Performance of Liquid Methane with Several Fluorine-Oxygen Mixtures Assuming Frozen Composition

NASA Technical Reports Server (NTRS)

Gordon, Sanford; Kastner, Michael E

1958-01-01

Theoretical rocket performance for frozen composition during expansion was calculated for liquid methane with several fluorine-oxygen mixtures for a range of pressure ratios and oxidant-fuel ratios. The parameters included are specific impulse, combustion-chamber temperature, nozzle-exit temperature molecular weight, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, isentropic exponent, viscosity, and thermal conductivity. The maximum calculated value of specific impulse for a chamber pressure of 600 pounds per square inch absolute (40.827atm) and an exit pressure of 1 atmosphere is 315.3 for 79.67 percent fluorine in the oxidant.

Pitot-Pressure Measurements in Flow Fields Behind a Rectangular Nozzle with Exhaust Jet for Free-Stream Mach Numbers of 0.00, 0.60, and 1.20

NASA Technical Reports Server (NTRS)

Putnam, L. E.; Mercer, C. E.

1986-01-01

An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to measure the flow field in and around the jet exhaust from a nonaxisymmetric nozzle configuration. The nozzle had a rectangular exit with a width-to-height ratio of 2.38. Pitot-pressure measurements were made at five longitudinal locations downstream of the nozzle exit. The maximum distance downstream of the exit was about 5 nozzle heights. These measurements were made at free-stream Mach numbers of 0.00, 0.60, and 1.20 with the nozzle operating at a ratio of nozzle total pressure to free-stream static pressure of 4.0. The jet exhaust was simulated with high-pressure air that had an exit total temperature essentially equal to the free-stream total temperature.

Temperature Measurements of High-Z Plasma Exiting the Laser Entrance Hole of Ignition Scale Depleted Uranium Hohlraums

NASA Astrophysics Data System (ADS)

Parrilla, Nicholas; Ralph, Joe; Bachmann, Ben; Goyon, Clement; Dewald, Eduard

2017-10-01

The temperature profile from the Laser Entrance Hole to 3.5 mm from the exit point was measured for plasma with high atomic number (high-Z) of Depleted Uranium ignition scale hohlraums. Each hohlraum was filled with 0.6 mg/cc He as part of the high foot CH campaign. Temperature of the flowing plasma is measured by fitting the velocity distribution to a Maxwellian and considering the Planckian spectral distributions with and without a 42 um Ge filter. The two spectra are then compared to determine the temperature of the high-Z plasma.

Analytical solution for heat transfer in three-dimensional porous media including variable fluid properties

NASA Technical Reports Server (NTRS)

Siegel, R.; Goldstein, M. E.

1972-01-01

An analytical solution is obtained for flow and heat transfer in a three-dimensional porous medium. Coolant from a reservoir at constant pressure and temperature enters one portion of the boundary of the medium and exits through another portion of the boundary which is at a specified uniform temperature and uniform pressure. The variation with temperature of coolant density and viscosity are both taken into account. A general solution is found that provides the temperature distribution in the medium and the mass and heat fluxes along the portion of the surface through which the coolant is exiting.

Vegetative Succession in Recently Deglaciated Land in Kenai Fjords National Park

NASA Astrophysics Data System (ADS)

Green, C.; Klein, A. G.; Cairns, D. M.

2017-12-01

Poleward vegetation expansion has affected Alaska for decades and due to recently increased rates of warming, the expansion will accelerate. Glacial recession in Kenai Fjords National Park has exposed previously ice-covered land with vegetation succession occurring just a few years following glacial retreat. Land cover changes in recently deglaciated areas are affected by surface-air interactions, temperature gradients, and ecosystem development. Using satellite images from Landsat 5, 7, and 8 and the previous extents of four retreating glaciers from 1985 to 2015 within Kenai Fjords National Park, this study examines the relationship between deglaciation rates and vegetation greening. The glaciers, Exit (-15.04 m/yr), Petrof (-31.12 m/yr), Lowell (-33.14 m/yr), and Yalik (-51.32 m/yr) were selected based on their location, whether they were land or lake terminating, and their average retreat rate measured between 1985 and 2015. These glaciers have also been extensively studied. Combining historic glacier extents with 371 summer (JJA) Landsat images gathered from Google's Earth Engine platform we identified annual summer changes in NDVI of locations that were deglaciated between 1985, 1995, 2005, and 2015. Summer temperature maximums were determined to be more correlated with deglaciation, as measured using NDSI, than mean summer temperatures. Using NDVI, heightened deglaciation rates were found to be reasonably correlated with vegetation succession. The faster retreating glaciers, Lowell and Yalik, exhibited higher mean and maximum rates of increase of NDVI in their terminus areas than Exit and Petrof, the two slower retreating glaciers.

120 DEG C Cure, Durable, Corrosion Protection Powder Coatings for Temperature Sensitive Substrates

DTIC Science & Technology

2005-01-28

Extrudate was passed through water-cooled pinch-rolls and collected onto a stainless steel belt; from exit of the extruder, approximately 60 sec... stainless steel belt; from exit of the extruder, approximately 60 sec. was required to reach ambient temperature. Production scale processing at...inherently free from volatile organic compounds, chromates, and hazardous air pollutants. Relative to the incumbent solvent-borne urethane paint

Baffles Promote Wider, Thinner Silicon Ribbons

NASA Technical Reports Server (NTRS)

Seidensticker, Raymond G.; Mchugh, James P.; Hundal, Rolv; Sprecace, Richard P.

1989-01-01

Set of baffles just below exit duct of silicon-ribbon-growing furnace reduces thermal stresses in ribbons so wider ribbons grown. Productivity of furnace increased. Diverts plume of hot gas from ribbon and allows cooler gas from top of furnace to flow around. Also shields ribbon from thermal radiation from hot growth assembly. Ribbon cooled to lower temperature before reaching cooler exit duct, avoiding abrupt drop in temperature as entering duct.

Theoretical performance of liquid hydrogen and liquid fluorine as a rocket propellant

NASA Technical Reports Server (NTRS)

Gordon, Sanford; Huff, Vearl N

1953-01-01

Theoretical values of performance parameters for liquid hydrogen and liquid fluorine as a rocket propellant were calculated on the assumption of equilibrium composition during the expansion process for a wide range of fuel-oxidant and expansion ratios. The parameters included were specific impulse, combustion-chamber temperature, nozzle-exit temperature, equilibrium composition, mean molecular weight, characteristic velocity, coefficient of thrust, ration of nozzle-exit area to throat area, specific heat at constant pressure, coefficient of viscosity, and coefficient of thermal conductivity. The maximum value of specific impulse was 364.6 pound-seconds per pound for a chamber pressure of 300 pounds per square inch absolute (20.41 atm) and an exit pressure of 1 atmosphere.

Theoretical performance of liquid ammonia and liquid fluorine as a rocket propellant

NASA Technical Reports Server (NTRS)

Gordon, Sanford; Huff, Vearl N

1953-01-01

Theoretical values of performance parameters for liquid ammonia and liquid fluorine as a rocket propellant were calculated on the assumption of equilibrium composition during the expansion process for a wide range of fuel-oxidant and expansion ratios. The parameters included were specific impulse, combustion chamber temperature, nozzle-exit temperature, equilibrium composition, mean molecular weight, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, coefficient of viscosity, and coefficient of thermal conductivity. The maximum value of specific impulse was 311.5 pound-seconds per pound for a chamber pressure of 300 pounds per square inch absolute (20.41 atm) and an exit pressure of 1 atmosphere.

Transition duct system with arcuate ceramic liner for delivering hot-temperature gases in a combustion turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebe, David J.

A transition duct system (10) for delivering hot-temperature gases from a plurality of combustors in a combustion turbine engine is provided. The system includes an exit piece (16) for each combustor. The exit piece may include an arcuate connecting segment (36). An arcuate ceramic liner (60) may be inwardly disposed onto a metal outer shell (38) along the arcuate connecting segment of the exit piece. Structural arrangements are provided to securely attach the ceramic liner in the presence of substantial flow path pressurization. Cost-effective serviceability of the transition duct systems is realizable since the liner can be readily removed andmore » replaced as needed.« less

Stagnation point properties for non-continuum gaseous jet impinging at a flat plate surface from a planar exit

NASA Astrophysics Data System (ADS)

Cai, Chunpei

2013-10-01

In this paper, we investigate highly rarefied gaseous jet flows out of a planar exit and impinging at a normally set flat plate. Especially, we concentrate on the plate center stagnation point pressure and heat flux coefficients. For a specular reflective plate, the stagnation point pressure coefficient can be represented using two non-dimensional factors: the characteristic gas exit speed ratio S0 and the geometry ratio of H/L, where H is the planar exit semi-height and L is the center-to-center distance from the exit to the plate. For a diffuse reflective plate, the stagnation point pressure and heat flux coefficients involve an extra factor of T0/Tw, i.e., the ratio of exit gas temperature to the plate wall temperature. These results allow us to develop four diagrams, from which we can conveniently obtain the pressure and heat flux coefficients for the stagnation impingement point, at the collisionless flow limit. After normalization with these maximum coefficients, the pressure and heat flux coefficient distributions along the surface essentially degenerate to almost identical curves. As a result, with known plate surface pressure coefficient distributions and these diagrams, we can conveniently construct the heat flux coefficient distributions along the plate surface, and vice versa.

Cross spectra between temperature and pressure in a constant area duct downstream of a combustor

NASA Technical Reports Server (NTRS)

Miles, J. H.; Wasserbauer, C. A.; Krejsa, E. A.

1983-01-01

The feasibility of measuring pressure temperature cross spectra and coherence and temperature-temperature cross spectra and coherence at spatially separated points along with pressure and temperature auto-spectra in a combustion rig was investigated. The measurements were made near the inlet and exit of a 6.44 m long duct attached to a J-47 combustor. The fuel used was Jet A. The cross spectra and coherence measurements show the pressure and temperature fluctuations correlate best at low frequencies. At the inlet the phenomena controlling the phase relationship between pressure and temperature could not be identified. However, at the duct exit the phase angle of the pressure is related to the phase angle of the temperature by the convected flow time delay.

Performance of a high-work, low-aspect-ratio turbine stator tested with a realistic inlet radial temperature gradient

NASA Technical Reports Server (NTRS)

Stabe, Roy G.; Schwab, John R.

1991-01-01

A 0.767-scale model of a turbine stator designed for the core of a high-bypass-ratio aircraft engine was tested with uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The principal measurements were radial and circumferential surveys of stator-exit total temperature, total pressure, and flow angle. The stator-exit flow field was also computed by using a three-dimensional Navier-Stokes solver. Other than temperature, there were no apparent differences in performance due to the inlet conditions. The computed results compared quite well with the experimental results.

Review of Rover fuel element protective coating development at Los Alamos

NASA Technical Reports Server (NTRS)

Wallace, Terry C.

1991-01-01

The Los Alamos Scientific Laboratory (LASL) entered the nuclear propulsion field in 1955 and began work on all aspects of a nuclear propulsion program with a target exhaust temperature of about 2750 K. A very extensive chemical vapor deposition coating technology for preventing catastrophic corrosion of reactor core components by the high temperature, high pressure hydrogen propellant gas was developed. Over the 17-year term of the program, more than 50,000 fuel elements were coated and evaluated. Advances in performance were achieved only through closely coupled interaction between the developing fuel element fabrication and protective coating technologies. The endurance of fuel elements in high temperature, high pressure hydrogen environment increased from several minutes at 2000 K exit gas temperature to 2 hours at 2440 K exit gas temperature in a reactor test and 10 hours at 2350 K exit gas temperature in a hot gas test. The purpose of this paper is to highlight the rationale for selection of coating materials used (NbC and ZrC), identify critical fuel element-coat interactions that had to be modified to increase system performance, and review the evolution of protective coating technology.

Computational and Experimental Characterization of the Mach 6 Facility Nozzle Flow for the Enhanced Injection and Mixing Project at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Drozda, Tomasz G.; Cabell, Karen F.; Passe, Bradley J.; Baurle, Robert A.

2017-01-01

Computational fluid dynamics analyses and experimental data are presented for the Mach 6 facility nozzle used in the Arc-Heated Scramjet Test Facility for the Enhanced Injection and Mixing Project (EIMP). This project, conducted at the NASA Langley Research Center, aims to investigate supersonic combustion ramjet (scramjet) fuel injection and mixing physics relevant to flight Mach numbers greater than 8. The EIMP experiments use a two-dimensional Mach 6 facility nozzle to provide the high-speed air simulating the combustor entrance flow of a scramjet engine. Of interest are the physical extent and the thermodynamic properties of the core flow at the nozzle exit plane. The detailed characterization of this flow is obtained from three-dimensional, viscous, Reynolds-averaged simulations. Thermodynamic nonequilibrium effects are also investigated. The simulations are compared with the available experimental data, which includes wall static pressures as well as in-stream static pressure, pitot pressure and total temperature obtained via in-stream probes positioned just downstream of the nozzle exit plane.

Heat transfer characteristics within an array of impinging jets. Effects of crossflow temperature relative to jet temperature

NASA Technical Reports Server (NTRS)

Florschuetz, L. W.; Su, C. C.

1985-01-01

Spanwise average heat fluxes, resolved in the streamwise direction to one stream-wise hole spacing were measured for two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate. The jet flow, after impingement, was constrained to exit in a single direction along the channel formed by the jet orifice plate and heat transfer surface. The crossflow originated from the jets following impingement and an initial crossflow was present that approached the array through an upstream extension of the channel. The regional average heat fluxes are considered as a function of parameters associated with corresponding individual spanwise rows within the array. A linear superposition model was employed to formulate appropriate governing parameters for the individual row domain. The effects of flow history upstream of an individual row domain are also considered. The results are formulated in terms of individual spanwise row parameters. A corresponding set of streamwise resolved heat transfer characteristics formulated in terms of flow and geometric parameters characterizing the overall arrays is described.

Design of a Mach-3 Nozzle for TBCC Testing in the NASA LaRC 8-ft High Temperature Tunnel

NASA Technical Reports Server (NTRS)

Gaffney, Richard L., Jr.; Norris, Andrew T.

2008-01-01

A new nozzle is being constructed for the NASA Langley Research Center 8-Foot High Temperature Tunnel. The axisymmetric nozzle was designed with a Mach-3 exit flow for testing Turbine-Based Combined-Cycle engines at a Mach number in the vicinity of the transition from turbojet to ramjet operation. The nozzle contour was designed using the NASA Langley IMOCND computer program which solves the potential equation using the classical method of characteristics. To include viscous effects, the design procedure iterated the MOC contour generation with CFD Navier-Stokes calculations, adjusting MOC input parameters until target nozzle-exit conditions were achieved in the Navier-Stokes calculations. The design process was complicated by a requirement to use the final 29.5 inches of an existing 54.5-inch exit-diameter Mach-5 nozzle contour. This was accomplished by generating a Mach-3 contour that matched the radius of the Mach-5 contour at the match point and using a 3rd order polynomial to create a smooth transition between the two contours. During the final evaluation of the design it was realized that the throat diameter is more than half that of the upstream mixing chamber. This led to the concern that large vortical structures generated in the mixer would persist downstream, affecting nozzle-exit flow. This concern was addressed by analyzing the results of three-dimensional, viscous, numerical simulations of the entire flowfield, from the exit of the facility combustor to the nozzle exit. An analysis of the solution indicated that large scale structures do not pass through the throat and that both the total temperature and species (CO2) are well mixed in the mixer, providing uniform flow to the nozzle and subsequently the test cabin.

Simulation and analysis of traffic flow based on cellular automaton

NASA Astrophysics Data System (ADS)

Ren, Xianping; Liu, Xia

2018-03-01

In this paper, single-lane and two-lane traffic model are established based on cellular automaton. Different values of vehicle arrival rate at the entrance and vehicle departure rate at the exit are set to analyze their effects on density, average speed and traffic flow. If the road exit is unblocked, vehicles can pass through the road smoothly despite of the arrival rate at the entrance. If vehicles enter into the road continuously, the traffic condition is varied with the departure rate at the exit. To avoid traffic jam, reasonable vehicle departure rate should be adopted.

Revisit the faster-is-slower effect for an exit at a corner

NASA Astrophysics Data System (ADS)

Chen, Jun Min; Lin, Peng; Wu, Fan Yu; Li Gao, Dong; Wang, Guo Yuan

2018-02-01

The faster-is-slower effect (FIS), which means that crowd at a high enough velocity could significantly increase the evacuation time to escape through an exit, is an interesting phenomenon in pedestrian dynamics. Such phenomenon had been studied widely and has been experimentally verified in different systems of discrete particles flowing through a centre exit. To experimentally validate this phenomenon by using people under high pressure is difficult due to ethical issues. A mouse, similar to a human, is a kind of self-driven and soft body creature with competitive behaviour under stressed conditions. Therefore, mice are used to escape through an exit at a corner. A number of repeated tests are conducted and the average escape time per mouse at different levels of stimulus are analysed. The escape times do not increase obviously with the level of stimulus for the corner exit, which is contrary to the experiment with the center exit. The experimental results show that the FIS effect is not necessary a universal law for any discrete system. The observation could help the design of buildings by relocating their exits to the corner in rooms to avoid the formation of FIS effect.

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, John H.; Stirling, William L.

1986-01-01

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, J.H.; Stirling, W.L.

1985-03-04

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

An Automated Temperature Controller for the Advanced Hall Effect Experimental Data Acquisition System.

DTIC Science & Technology

1982-03-01

ENTRY: ACCA CONTAINS THE CHARACTER EXIT: ACCA CONTAINS THE CHARACTER DISPLAY TAilLE UPDATKD DISPLAY POINTER INCREMENTED VOLATILE RECISTERS: B...OUTPUTS THE RIC11T HALF-BYTE OF THE HEX NUMBER CON- TAINED IN ACCA TO THE DISPLAY. ENTRY: ACCA CONTAINS THE HEX NUMBER EXIT: ACCA CONTAINS THE HEX...OUTPUTS THE LEFT HALF-BYTE OF THE HEX NUMBER CON- TAINED IN ACCA TO THE DISPLAY. ENTRY: ACCA CONTAINS THE HEX NUMBER EXIT: ACCA CONTAINS THE HEX

Gaseous hydrogen/oxygen injector performance characterization

NASA Technical Reports Server (NTRS)

Degroot, W. A.; Tsuei, H. H.

1994-01-01

Results are presented of spontaneous Raman scattering measurements in the combustion chamber of a 110 N thrust class gaseous hydrogen/oxygen rocket. Temperature, oxygen number density, and water number density profiles at the injector exit plane are presented. These measurements are used as input profiles to a full Navier-Stokes computational fluid dynamics (CFD) code. Predictions of this code while using the measured profiles are compared with predictions while using assumed uniform injector profiles. Axial and radial velocity profiles derived from both sets of predictions are compared with Rayleigh scattering measurements in the exit plane of a 33:1 area ratio nozzle. Temperature and number density Raman scattering measurements at the exit plane of a test rocket with a 1:1.36 area ratio nozzle are also compared with results from both sets of predictions.

Transition duct system with straight ceramic liner for delivering hot-temperature gases in a combustion turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebe, David J.

A transition duct system (10) for delivering hot-temperature gases from a plurality of combustors in a combustion turbine engine is provided. The system includes an exit piece (16) for each combustor. The exit piece may include a straight path segment (26) for receiving a gas flow from a respective combustor. A straight ceramic liner (40) may be inwardly disposed onto a metal outer shell (38) along the straight path segment of the exit piece. Structural arrangements are provided to securely attach the ceramic liner in the presence of substantial flow path pressurization. Cost-effective serviceability of the transition duct systems ismore » realizable since the liner can be readily removed and replaced as needed.« less

An experimental and numerical study of gas jet diffusion flames enveloped by a cascade of venturis

NASA Astrophysics Data System (ADS)

Qubbaj, Ala Rafat

1999-06-01

A new technique to control carbon monoxide, nitric oxide, and soot emissions of a propane diffusion flame by modifying the air infusion rate into the flame was developed. In this study, the effectiveness of the ``venturi-cascading'' technique was experimentally as well numerically investigated. Propane jet diffusion flames at three burner-exit Reynolds numbers ( 3600, 5100 and 6500) corresponding to burner-rim-attached, undergoing transition from attached to lifted, and fully-lifted configurations were examined with several sets of venturis of different sizes and spacing arrangements. Temperature, and the concentrations of carbon dioxide, oxygen, carbon monoxide and nitric oxide in the exhaust products were measured before and after the modification, and optimal conditions to minimize pollutant emissions were obtained. The optimal value of venturi throat/burner-exit diameter ratio (D/d) was 32 +/- 3, which corresponded to an approximate clearance of 5 +/- 2 mm between the venturi throat and the burning jet width at the mid-flame height. The venturi-cascading technique at its optimal conditions resulted in a decrease of 87% and 33% in CO and NO emission indices along with a 24% decrease in soot emission from a propane jet flame, compared to the baseline condition (same flame without venturis). The reduction of NO without increasing CO was the main attraction of this technique. The temperature and composition measurements, at the optimal conditions, showed that, in the near-burner region, the venturi-cascaded flame had lower temperature and CO2 concentration by an average of 5% and 7%, respectively, than the baseline flame. However, in the mid-flame and far-burner regions, it has higher temperature by 13% and 12%, and higher CO2 concentration by 16% and 13%, in average values, respectively. Laser Induced Fluorescence (LIF) measurements, in the near-burner region of the venturi-cascaded flame, indicated an average decrease of 18%, 24% and 12% in OH, CH and CN radical species, respectively, along with 11% drop in soot precursors (PAR), from their baseline values. The thermal and composition fields of the baseline and venturi-cascaded flames were numerically simulated using CFD-ACE+, an advanced computational environment software package. The CO and NO concentrations were determined through CFD-POST, a post processing utility program for CFD-ACE+. The final simulated results were compared with the experimental data. Good agreement was found in the near-burner region. (Abstract shortened by UMI.)

Results of the Mariner 6 and 7 Mars occultation experiments

NASA Technical Reports Server (NTRS)

Hogan, J. S.; Stewart, R. W.; Rasool, S. I.; Russell, L. H.

1972-01-01

Final profiles of temperature, pressure, and electron density on Mars were obtained for the Mariner 6 and 7 entry and exit cases, and results are presented for both the lower atmosphere and ionosphere. The results of an analysis of the systematic and formal errors introduced at each stage of the data-reduction process are also included. At all four occulation points, the lapse rate of temperature was subdadiabatic up to altitudes in excess of 20 km. A pronounced temperature inversion was present above the surface at the Mariner 6 exit point. All four profiles exhibit a sharp, superadiabatic drop in temperature at high altitudes, with temperatures falling below the frost point of CO2. These results give a strong indication of frozen CO2 in the middle atmosphere of Mars.

Regulation of body temperature in the blue-tongued lizard.

PubMed

Hammel, H T; Caldwell, F T; Abrams, R M

1967-06-02

Lizards (Tiliqua scincoides) regulated their internal body temperature by moving back and forth between 15 degrees and 45 degrees C environments to maintain colonic and brain temperatures between 30 degrees and 37 degrees C. A pair of thermodes were implanted across the preoptic region of the brain stem, and a reentrant tube for a thermocouple was implanted in the brain stem. Heating the brain stem to 41 degrees C activated the exit response from the hot environment at a colonic temperature 1 degrees to 2 degrees C lower than normal, whereas cooling the brain stem to 25 degrees C delayed the exit from the hot environment until the colonic temperature was 1 degrees to 2 degrees C higher than normal. The behavioral thermoregulatory responses of this ectotherm appear to be activated by a combination of hypothalamic and other body temperatures.

Medicare payment reform and provider entry and exit in the post-acute care market.

PubMed

Huckfeldt, Peter J; Sood, Neeraj; Romley, John A; Malchiodi, Alessandro; Escarce, José J

2013-10-01

To understand the impacts of Medicare payment reform on the entry and exit of post-acute providers. Medicare Provider of Services data, Cost Reports, and Census data from 1991 through 2010. We examined market-level changes in entry and exit after payment reforms relative to a preexisting time trend. We also compared changes in high Medicare share markets relative to lower Medicare share markets and for freestanding relative to hospital-based facilities. We calculated market-level entry, exit, and total stock of home health agencies, skilled nursing facilities, and inpatient rehabilitation facilities from Provider of Services files between 1992 and 2010. We linked these measures with demographic information from the Census and American Community Survey, information on Certificate of Need laws, and Medicare share of facilities in each market drawn from Cost Report data. Payment reforms reducing average and marginal payments reduced entries and increased exits from the market. Entry effects were larger and more persistent than exit effects. Entry and exit rates fluctuated more for home health agencies than skilled nursing facilities. Effects on number of providers were consistent with entry and exit effects. Payment reform affects market entry and exit, which in turn may affect market structure, access to care, quality and cost of care, and patient outcomes. Policy makers should consider potential impacts of payment reforms on post-acute care market structure when implementing these reforms. © Health Research and Educational Trust.

Medicare Payment Reform and Provider Entry and Exit in the Post-Acute Care Market

PubMed Central

Huckfeldt, Peter J; Sood, Neeraj; Romley, John A; Malchiodi, Alessandro; Escarce, José J

2013-01-01

Objective To understand the impacts of Medicare payment reform on the entry and exit of post-acute providers. Data Sources Medicare Provider of Services data, Cost Reports, and Census data from 1991 through 2010. Study Design We examined market-level changes in entry and exit after payment reforms relative to a preexisting time trend. We also compared changes in high Medicare share markets relative to lower Medicare share markets and for freestanding relative to hospital-based facilities. Data Extraction Methods We calculated market-level entry, exit, and total stock of home health agencies, skilled nursing facilities, and inpatient rehabilitation facilities from Provider of Services files between 1992 and 2010. We linked these measures with demographic information from the Census and American Community Survey, information on Certificate of Need laws, and Medicare share of facilities in each market drawn from Cost Report data. Principal Findings Payment reforms reducing average and marginal payments reduced entries and increased exits from the market. Entry effects were larger and more persistent than exit effects. Entry and exit rates fluctuated more for home health agencies than skilled nursing facilities. Effects on number of providers were consistent with entry and exit effects. Conclusions Payment reform affects market entry and exit, which in turn may affect market structure, access to care, quality and cost of care, and patient outcomes. Policy makers should consider potential impacts of payment reforms on post-acute care market structure when implementing these reforms. PMID:23557215

Occupational and educational inequalities in exit from employment at older ages: evidence from seven prospective cohorts.

PubMed

Carr, Ewan; Fleischmann, Maria; Goldberg, Marcel; Kuh, Diana; Murray, Emily T; Stafford, Mai; Stansfeld, Stephen; Vahtera, Jussi; Xue, Baowen; Zaninotto, Paola; Zins, Marie; Head, Jenny

2018-05-01

Past studies have identified socioeconomic inequalities in the timing and route of labour market exit at older ages. However, few studies have compared these trends cross-nationally and existing evidence focuses on specific institutional outcomes (such as disability pension and sickness absence) in Nordic countries. We examined differences by education level and occupational grade in the risks of work exit and health-related work exit. Prospective longitudinal data were drawn from seven studies (n=99 164). Participants were in paid work at least once around age 50. Labour market exit was derived based on reductions in working hours, changes in self-reported employment status or from administrative records. Health-related exit was ascertained by receipt of health-related benefit or pension or from the reported reason for stopping work. Cox regression models were estimated for each study, adjusted for baseline self-rated health and birth cohort. There were 50 003 work exits during follow-up, of which an average of 14% (range 2-32%) were health related. Low level education and low occupational grade were associated with increased risks of health-related exit in most studies. Low level education and occupational grade were also associated with an increased risk of any exit from work, although with less consistency across studies. Workers with low socioeconomic position have an increased risk of health-related exit from employment. Policies that extend working life may disadvantage such workers disproportionally, especially where institutional support for those exiting due to poor health is minimal. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The rate of the reaction between CN and C2H2 at interstellar temperatures.

PubMed

Woon, D E; Herbst, E

1997-03-01

The rate coefficient for the important interstellar reaction between CN and C2H2 has been calculated as a function of temperature between 10 and 300 K. The potential surface for this reaction has been determined through ab initio quantum chemical techniques; the potential exhibits no barrier in the entrance channel but does show a small exit channel barrier, which lies below the energy of reactants. Phase-space calculations for the reaction dynamics, which take the exit channel barrier into account, show the same unusual temperature dependence as determined by experiment, in which the rate coefficient at first increases as the temperature is reduced below room temperature and then starts to decrease as the temperature drops below 50-100 K. The agreement between theory and experiment provides strong confirmation that the reaction occurs appreciably at cool interstellar temperatures.

Water cooled static pressure probe

NASA Technical Reports Server (NTRS)

Lagen, Nicholas T. (Inventor); Eves, John W. (Inventor); Reece, Garland D. (Inventor); Geissinger, Steve L. (Inventor)

1991-01-01

An improved static pressure probe containing a water cooling mechanism is disclosed. This probe has a hollow interior containing a central coolant tube and multiple individual pressure measurement tubes connected to holes placed on the exterior. Coolant from the central tube symmetrically immerses the interior of the probe, allowing it to sustain high temperature (in the region of 2500 F) supersonic jet flow indefinitely, while still recording accurate pressure data. The coolant exits the probe body by way of a reservoir attached to the aft of the probe. The pressure measurement tubes are joined to a single, larger manifold in the reservoir. This manifold is attached to a pressure transducer that records the average static pressure.

On entanglement of light and Stokes parameters

NASA Astrophysics Data System (ADS)

Żukowski, Marek; Laskowski, Wiesław; Wieśniak, Marcin

2016-08-01

We present a new approach to Stokes parameters, which enables one to see better non-classical properties of bright quantum light, and of undefined overall photon numbers. The crucial difference is as follows. The standard quantum optical Stokes parameters are averages of differences of intensities of light registered at the two exits of polarization analyzers, and one gets their normalized version by dividing them by the average total intensity. The new ones are averages of the registered normalized Stokes parameters, for the duration of the experiment. That is, we redefine each Stokes observable as the difference of photon number operators at the two exits of a polarizing beam splitter multiplied by the inverse of their sum. The vacuum eigenvalue of the operator is defined a zero. We show that with such an approach one can obtain more sensitive entanglement indicators based on polarization measurements.

Performance and emission characteristics of swirl-can combustors to near-stoichiometric fuel-air ratio

NASA Technical Reports Server (NTRS)

Diehl, L. A.; Trout, A. M.

1976-01-01

Emissions and performance characteristics were determined for two full annular swirl-can combustors operated to near stoichiometric fuel-air ratio. Test condition variations were as follows: combustor inlet-air temperatures, 589, 756, 839, and 894 K; reference velocities, 24 to 37 meters per second; inlet pressure, 62 newtons per square centimeter; and fuel-air ratios, 0.015 to 0.065. The combustor average exit temperature and combustor efficiency were calculated from the combustor exhaust gas composition. For fuel-air ratios greater than 0.04, the combustion efficiency decreased with increasing fuel-air ratios in a near-linear manner. Increasing the combustor inlet air temperature tended to offset this decrease. Maximum oxides of nitrogen emission indices occurred at intermediate fuel-air ratios and were dependent on combustor design. Carbon monoxide levels were extremely high and were the primary cause of poor combustion efficiency at the higher fuel-air ratios. Unburned hydrocarbons were low for all test conditions. For high fuel-air ratios SAE smoke numbers greater than 25 were produced, except at the highest inlet-air temperatures.

Transition duct system with metal liners for delivering hot-temperature gases in a combustion turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebe, David J.

A transition duct system (10) for delivering hot-temperature gases from a plurality of combustors in a combustion turbine engine is provided. The system includes an exit piece (16) for each combustor. The exit piece may include a straight path segment (26) and an arcuate connecting segment (36). A respective straight metal liner (92) and an arcuate metal liner (94) may be each inwardly disposed onto a metal outer shell (38) along the straight path segment and the arcuate connecting segment (36) of the exit piece. Structural arrangements are provided to securely attach the respective liners in the presence of substantialmore » flow path pressurization. Cost-effective serviceability of the transition duct systems is realizable since the liners can be readily removed and replaced as needed.« less

A simple analytical method to estimate all exit parameters of a cross-flow air dehumidifier using liquid desiccant.

PubMed

Bassuoni, M M

2014-03-01

The dehumidifier is a key component in liquid desiccant air-conditioning systems. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the performance results of exit parameters from an analytical model of an adiabatic cross-flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. A program performing the analytical solution is developed using the engineering equation solver software. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and -5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration, and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier. The moisture removal rate is decreased with increasing both air inlet temperature and desiccant temperature while increases with increasing air to solution mass ratio, inlet desiccant concentration, and inlet air humidity ratio.

Pioneer 10 and 11 radio occultations by Jupiter. [atmospheric temperature structure

NASA Technical Reports Server (NTRS)

Kliore, A. J.; Woiceshyn, P. M.; Hubbard, W. B.

1977-01-01

Results on the temperature structure of the Jovian atmosphere are reviewed which were obtained by applying an integral inversion technique combined with a model for the planet's shape based on gravity data to Pioneer 10 and 11 radio-occultation data. The technique applied to obtain temperature profiles from the Pioneer data consisted of defining a center of refraction based on a computation of the radius of curvature in the plane of refraction and the normal direction to the equipotential surface at the closest approach point of a ray. Observations performed during the Pioneer 10 entry and exit and the Pioneer 11 exit are analyzed, sources of uncertainty are identified, and representative pressure-temperature profiles are presented which clearly show a temperature inversion between 10 and 100 mb. Effects of zonal winds on the reliability of radio-occultation temperature profiles are briefly discussed.

Inferring total canopy APAR from PAR bidirectional reflectances and vegetation indices in tallgrass prairie. [Absorbed Photosynthetically Active Radiation

NASA Technical Reports Server (NTRS)

Middleton, Elizabeth M.

1992-01-01

The fraction of photosynthetically active radiation (PAR) absorbed by a vegetated canopy (APARc) or landscape (APARs) is a critical parameter in climate processes. A grassland study examined: 1) whether APARs can be estimated from PAR bidirectional exitance fractions; and 2) whether APARs is correlated with spectral vegetation indices (SVIs). Data were acquired with a high resolution continuous spectroradiometer at 4 sun angles on grassland sites. APARs was computed from the scattered surface PAR exitance fractions. The nadir APARs value was the most variable diurnally; it provided a good estimate of the average surface APARs at 95 percent. APARc was best represented by exitance factors between 30-60* forward.

Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

NASA Astrophysics Data System (ADS)

Akahoshi, Hikaru; Takahashi, Kazunori; Ando, Akira

2018-03-01

High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf) inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

Species and temperature measurement in H2/O2 rocket flow fields by means of Raman scattering diagnostics

NASA Technical Reports Server (NTRS)

De Groot, Wim A.; Weiss, Jonathan M.

1992-01-01

Validation of CFD codes developed for prediction and evaluation of rocket performance is hampered by a lack of experimental data. Nonintrusive laser based diagnostics are needed to provide spatially and temporally resolved gas dynamic and fluid dynamic measurements. This paper reports the first nonintrusive temperature and species measurements in the plume of a 110 N gaseous hydrogen/oxygen thruster at and below ambient pressures, obtained with spontaneous Raman spectroscopy. Measurements at 10 mm downstream of the exit plane are compared with predictions from a numerical solution of the axisymmetric Navier-Stokes and species transport equations with chemical kinetics, which fully model the combustor-nozzle-plume flowfield. The experimentally determined oxygen number density at the centerline at 10 mm downstream of the exit plane is four times that predicted by the model. The experimental number density data fall between those numerically predicted for the exit and 10 mm downstream planes in both magnitude and radial gradient. The predicted temperature levels are within 10 to 15 percent of measured values.

Prior Individual Training and Self-Organized Queuing during Group Emergency Escape of Mice from Water Pool

PubMed Central

Saloma, Caesar; Perez, Gay Jane; Gavile, Catherine Ann; Ick-Joson, Jacqueline Judith; Palmes-Saloma, Cynthia

2015-01-01

We study the impact of prior individual training during group emergency evacuation using mice that escape from an enclosed water pool to a dry platform via any of two possible exits. Experimenting with mice avoids serious ethical and legal issues that arise when dealing with unwitting human participants while minimizing concerns regarding the reliability of results obtained from simulated experiments using ‘actors’. First, mice were trained separately and their individual escape times measured over several trials. Mice learned quickly to swim towards an exit–they achieved their fastest escape times within the first four trials. The trained mice were then placed together in the pool and allowed to escape. No two mice were permitted in the pool beforehand and only one could pass through an exit opening at any given time. At first trial, groups of trained mice escaped seven and five times faster than their corresponding control groups of untrained mice at pool occupancy rate ρ of 11.9% and 4%, respectively. Faster evacuation happened because trained mice: (a) had better recognition of the available pool space and took shorter escape routes to an exit, (b) were less likely to form arches that blocked an exit opening, and (c) utilized the two exits efficiently without preference. Trained groups achieved continuous egress without an apparent leader-coordinator (self-organized queuing)—a collective behavior not experienced during individual training. Queuing was unobserved in untrained groups where mice were prone to wall seeking, aimless swimming and/or blind copying that produced circuitous escape routes, biased exit use and clogging. The experiments also reveal that faster and less costly group training at ρ = 4%, yielded an average individual escape time that is comparable with individualized training. However, group training in a more crowded pool (ρ = 11.9%) produced a longer average individual escape time. PMID:25693170

Heat transfer rate and film cooling effectiveness measurements in a transient cascade

NASA Astrophysics Data System (ADS)

Schultz, D. L.; Oldfield, M. L. G.; Jones, T. V.

1980-09-01

A transient cascade useful for heat transfer rate measurements is briefly described. The facility employs a free piston which compresses the test gas to temperatures around 450 K and pressures of about 3.5 to 7.5 Atm. The model is initially at room temperature and it is necessary to attain the correct gas to wall temperature ratio. The exit Mach number is set by the inlet total pressure and the pressure in the exit dump tank. Thin film heat transfer gauges are used for the measurement of heat transfer rate, deposited on machineable glass ceramic blades. The inherently fast response of these transducers makes them useful for the investigation of boundary layer transition on blade surfaces and some typical results are included.

Ceramics for Solar Receivers

NASA Technical Reports Server (NTRS)

Kudirka, A. A.

1984-01-01

Materials for high-temperature use reviewed. Report discusses characteristics of ceramics and assesses potential of candidate materials in solar receivers. Design requirements presented, including those for receiver with fluid exit temperatures up to 1,425 degrees C.

Performance of a catalytic reactor at simulated gas turbine combustor operating conditions

NASA Technical Reports Server (NTRS)

Anderson, D. N.; Tacina, R. R.; Mroz, T. S.

1975-01-01

The performance of a catalytic reactor 12 cm in diameter and 17 cm long was evaluated at simulated gas turbine combustor operating conditions using premixed propane and air. Inlet temperatures of 600 and 800 K, pressures of 3 and 6 atm, and reference velocities of 9 to 30 m/s were tested. Data were taken for equivalence ratios as high as 0.43. The operating range was limited on the low-temperature side by very poor efficiency; the minimum exit temperature for good performance ranged from 1400 to 1600 K depending on inlet conditions. As exit temperatures were raised above this minimum, emissions of unburned hydrocarbons decreased, carbon monoxide emissions became generally less than 1 g CO/kg fuel, and nitrogen oxides were less than about 0.1 g NO2/kg fuel.

A simple analytical method to estimate all exit parameters of a cross-flow air dehumidifier using liquid desiccant

PubMed Central

Bassuoni, M.M.

2013-01-01

The dehumidifier is a key component in liquid desiccant air-conditioning systems. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the performance results of exit parameters from an analytical model of an adiabatic cross-flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. A program performing the analytical solution is developed using the engineering equation solver software. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and −5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration, and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier. The moisture removal rate is decreased with increasing both air inlet temperature and desiccant temperature while increases with increasing air to solution mass ratio, inlet desiccant concentration, and inlet air humidity ratio. PMID:25685485

Foundational Performance Analyses of Pressure Gain Combustion Thermodynamic Benefits for Gas Turbines

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Kaemming, Thomas A.

2012-01-01

A methodology is described whereby the work extracted by a turbine exposed to the fundamentally nonuniform flowfield from a representative pressure gain combustor (PGC) may be assessed. The method uses an idealized constant volume cycle, often referred to as an Atkinson or Humphrey cycle, to model the PGC. Output from this model is used as input to a scalable turbine efficiency function (i.e., a map), which in turn allows for the calculation of useful work throughout the cycle. Integration over the entire cycle yields mass-averaged work extraction. The unsteady turbine work extraction is compared to steady work extraction calculations based on various averaging techniques for characterizing the combustor exit pressure and temperature. It is found that averages associated with momentum flux (as opposed to entropy or kinetic energy) provide the best match. This result suggests that momentum-based averaging is the most appropriate figure-of-merit to use as a PGC performance metric. Using the mass-averaged work extraction methodology, it is also found that the design turbine pressure ratio for maximum work extraction is significantly higher than that for a turbine fed by a constant pressure combustor with similar inlet conditions and equivalence ratio. Limited results are presented whereby the constant volume cycle is replaced by output from a detonation-based PGC simulation. The results in terms of averaging techniques and design pressure ratio are similar.

Effect of Shrouding Gas Temperature on Characteristics of a Supersonic Jet Flow Field with a Shrouding Laval Nozzle Structure

NASA Astrophysics Data System (ADS)

Liu, Fuhai; Sun, Dongbai; Zhu, Rong; Li, Yilin

2018-05-01

Coherent jet technology was been widely used in the electric arc furnace steelmaking process to protect the kinetic energy of supersonic oxygen jets and achieve a better mixing effect. For this technology, the total temperature distribution of the shrouding jet has a great impact on the velocity of the main oxygen jet. In this article, a supersonic shrouding nozzle using a preheating shrouding jet is proposed to increase the shrouding jet velocity. Both numerical simulation and experimental studies were carried out to analyze its effect on the axial velocity, total temperature and turbulence kinetic energy profiles of the main oxygen jet. Based on these results, it was found that a significant amount of kinetic energy was removed from the main oxygen jet when it passed though the shock wave using a high-temperature shrouding jet, which made the average axial velocity of the coherent jet lower than for a conventional jet in the potential core region. However, the supersonic shrouding nozzle and preheating technology employed for this nozzle design significantly improved the shrouding gas velocity, forming a low-density gas zone at the exit of the main oxygen jet and prolonging the velocity potential core length.

Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

NASA Technical Reports Server (NTRS)

Einstein, Thomas H.

1961-01-01

Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

Evaluation of circularity error in drilling of syntactic foam composites

NASA Astrophysics Data System (ADS)

Ashrith H., S.; Doddamani, Mrityunjay; Gaitonde, Vinayak

2018-04-01

Syntactic foams are widely used in structural applications of automobiles, aircrafts and underwater vehicles due to their lightweight properties combined with high compression strength and low moisture absorption. Structural application requires drilling of holes for assembly purpose. In this investigation response surface methodology based mathematical models are used to analyze the effects of cutting speed, feed, drill diameter and filler content on circularity error both at entry and exit level in drilling of glass microballoon reinforced epoxy syntactic foam. Experiments are conducted based on full factorial design using solid coated tungsten carbide twist drills. The parametric analysis reveals that circularity error is highly influenced by drill diameter followed by spindle speed at the entry and exit level. Parametric analysis also reveals that increasing filler content decreases circularity error by 13.65 and 11.96% respectively at entry and exit levels. Average circularity error at the entry level is found to be 23.73% higher than at the exit level.

Theoretical Performance of Hydrogen-Oxygen Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Sievers, Gilbert K.; Tomazic, William A.; Kinney, George R.

1961-01-01

Data are presented for liquid-hydrogen-liquid-oxygen thrust chambers at chamber pressures from 15 to 1200 pounds per square inch absolute, area ratios to approximately 300, and percent fuel from about 8 to 34 for both equilibrium and frozen composition during expansion. Specific impulse in vacuum, specific impulse, combustion-chamber temperature, nozzle-exit temperature, characteristic velocity, and the ratio of chamber-to-nozzle-exit pressure are included. The data are presented in convenient graphical forms to allow quick calculation of theoretical nozzle performance with over- or underexpansion, flow separation, and introduction of the propellants at various initial conditions or heat loss from the combustion chamber.

Thermal Testing and Integration: Magnetospheric MultiScale (MMS) Observatories with Digital 1-Wire Sensors

NASA Technical Reports Server (NTRS)

Solimani, Jason A.; Rosanova, Santino

2015-01-01

Thermocouples require two thin wires to be routed out of the spacecraft to connect to the ground support equipment used to monitor and record the temperature data. This large number of wires that exit the observatory complicates integration and creates an undesirable heat path during testing. These wires exiting the spacecraft need to be characterized as a thermal short that will not exist during flight. To minimize complexity and reduce thermal variables from these ground support equipment (GSE) wires, MMS pursued a hybrid path for temperature monitoring, utilizing thermocouples and digital 1-wire temperature sensors. Digital 1-wire sensors can greatly reduce harness mass, length and complexity as they can be spliced together. For MMS, 350 digital 1-wire sensors were installed on the spacecraft with only 18 wires exiting as opposed to a potential 700 thermocouple wires. Digital 1-wire sensors had not been used in such a large scale at NASAGSFC prior to the MMS mission. During the MMS thermal vacuum testing a lessons learned matrix was formulated that will assist future integration of 1-wires into thermal testing and one day into flight.

Effect of velocity and temperature distribution at the hole exit on film cooling of turbine blades

NASA Technical Reports Server (NTRS)

Garg, Vijay K.; Gaugler, Raymond E.

1995-01-01

An existing three-dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of coolant velocity and temperature distribution at the hole exit on the heat transfer coefficient on three-film-cooled turbine blades, namely, the C3X vane, the VKI rotor, and the ACE rotor. Results are also compared with the experimental data for all the blades. Moreover, Mayle's transition criterion, Forest's model for augmentation of leading edge heat transfer due to freestream turbulence, and Crawford's model for augmentation of eddy viscosity due to film cooling are used. Use of Mayle's and Forest's models is relevant only for the ACE rotor due to the absence of showerhead cooling on this rotor. It is found that, in some cases, the effect of distribution of coolant velocity and temperature at the hole exit can be as much as 60% on the heat transfer coefficient at the blade suction surface, and 50% at the pressure surface. Also, different effects are observed on the pressure and suction surface depending upon the blade as well as upon the hole shape, conical or cylindrical.

Radial and circumferential flow surveys at the inlet and exit of the Space Shuttle Main Engine High Pressure Fuel Turbine Model

NASA Technical Reports Server (NTRS)

Hudson, S. T.; Bordelon, W. J., Jr.; Smith, A. W.; Ramachandran, N.

1995-01-01

The main objective of this test was to obtain detailed radial and circumferential flow surveys at the inlet and exit of the SSME High Pressure Fuel Turbine model using three-hole cobra probes, hot-film probes, and a laser velocimeter. The test was designed to meet several objectives. First, the techniques for making laser velocimeter, hot-film probe, and cobra probe measurements in turbine flows were developed and demonstrated. The ability to use the cobra probes to obtain static pressure and, therefore, velocity had to be verified; insertion techniques had to be established for the fragile hot-film probes; and a seeding method had to be established for the laser velocimetry. Once the measurement techniques were established, turbine inlet and exit velocity profiles, temperature profiles, pressure profiles, turbulence intensities, and boundary layer thicknesses were measured at the turbine design point. The blockage effect due to the model inlet and exit total pressure and total temperature rakes on the turbine performance was also studied. A small range of off-design points were run to obtain the profiles and to verify the rake blockage effects off-design. Finally, a range of different Reynolds numbers were run to study the effect of Reynolds number on the various measurements.

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2011 CFR

2011-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2013 CFR

2013-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2014 CFR

2014-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

Characteristics of cold atmospheric plasma source based on low-current pulsed discharge with coaxial electrodes

NASA Astrophysics Data System (ADS)

Bureyev, O. A.; Surkov, Yu S.; Spirina, A. V.

2017-05-01

This work investigates the characteristics of the gas discharge system used to create an atmospheric pressure plasma flow. The plasma jet design with a cylindrical graphite cathode and an anode rod located on the axis of the system allows to realize regularly reproducible spark breakdowns mode with a frequency ∼ 5 kHz and a duration ∼ 40 μs. The device generates a cold atmospheric plasma flame with 1 cm in diameter in the flow of various plasma forming gases including nitrogen and air at about 100 mA average discharge current. In the described construction the cathode spots of individual spark channels randomly move along the inner surface of the graphite electrode creating the secondary plasma stream time-average distributed throughout the whole exit aperture area after the decay of numerous filamentary discharge channels. The results of the spectral diagnostics of plasma in the discharge gap and in the stream coming out of the source are presented. Despite the low temperature of atoms and molecules in plasma stream the cathode spots operation with temperature of ∼ 4000 °C at a graphite electrode inside a discharge system enables to saturate the plasma by CN-radicals and atomic carbon in the case of using nitrogen as the working gas.

Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

NASA Astrophysics Data System (ADS)

Taler, Dawid; Sury, Adam

2011-12-01

The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.

Effect of area ratio on the performance of a 5.5:1 pressure ratio centrifugal impeller

NASA Technical Reports Server (NTRS)

Schumann, L. F.; Clark, D. A.; Wood, J. R.

1986-01-01

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was changed by successively cutting back the impeller exit axial width from an initial value of 7.57 mm to a final value of 5.97 mm. In all, four separate area ratios were tested. For each area ratio a series of impeller exit axial clearances was also tested. Test results are based on impeller exit surveys of total pressure, total temperature, and flow angle at a radius 1.115 times the impeller exit radius. Results of the tests at design speed, peak efficiency, and an exit tip clearance of 8 percent of exit blade height show that the impeller equivalent pressure recovery coefficient peaked at a design point area ratio of approximately 2.748 while the impeller aerodynamic efficiency peaked at a lower value of area ratio of approximately 2.55. The variation of impeller efficiency with clearance showed expected trends with a loss of approximately 0.4 points in impeller efficiency for each percent increase in exit axial tip clearance for all impellers tested.

The temporal evolution of pyroclast ejection velocity and exit trajectory, a laboratory case study.

NASA Astrophysics Data System (ADS)

Cigala, Valeria; Kueppers, Ulrich; José Peña Fernández, Juan; Sesterhenn, Jörn; Taddeucci, Jacopo; Dingwell, Donald Bruce

2017-04-01

Pyroclast ejection dynamics during explosive volcanic eruptions are highly variable. This variability is due to complex interaction among different parameters, which define the boundary conditions for a certain eruption. Scaled and controlled laboratory experiments come in hand to characterize the effect of specific physical parameters on the ejection dynamics. We focus, in particular, on the dynamics of pyroclasts ejection in the region just above the vent, also called gas-thrust region, for the case of impulsively released gas-pyroclast mixtures (i.e., unsteady eruptions). In this study, gas-particle mixtures were released in a series of shock-tube experiments with varying 1) tube length, 2) vent geometry, 3) gas-particle ratio, 4) initial temperature and 5) particle size distribution. The tube length was varied by changing the starting sample load, resulting in a gas-particle ratio of 1, 2.5 and 8, respectively. Thereby, the initial distance of the sample from the exit varied between 320, 230 and 140 mm, respectively, allowing for variable time for accelerating (and possibly decelerating) the particles prior to exit. Moreover, four vent geometries were employed, a nozzle with converging walls (5°), a cylinder and two funnels with walls diverging at 15° and 30° respectively. All of them are characterized by a value h/D=1.07, where h is the length between the throat and the lip of the vent and D is throat diameter. The experiments were performed at both 500°C and room temperature using particles from 2 to 0.125 mm in diameter. In all experiments, initial pressure was 15 MPa. High speed videos of the ejection behaviour were analyzed to obtain the temporal evolution of particle velocity and exit trajectory depending on boundary conditions. Max velocity of 300 m/s was observed together with a non-linear decay of exit velocity over time. The exit trajectories were found to deviate from the vertical by 5° to 45° and also display a non-linear evolution with time. Moreover, the velocity decay was used to investigate the accuracy of the empirical fragmentation depth model from Alatorre-Ibargüengoitia et al. (2011), when different gas-particle ratios are employed. This model is not reproducing all experimental constellations satisfactorily. Further experiments will help to develop this model further. Vent geometry, particle size and temperature show the largest effect on ejection velocity and trajectory. In particular, we observed a positive correlation of velocity with 1) diverging vent walls and 2) temperature and a negative correlation with 1) starting tube length and 2) particle size. On the other hand, exit trajectories show negative correlation with 1) diverging walls, 2) starting tube length, 3) temperature and 4) particle size. Moreover, we found that gas-particle ratio additionally strongly affects the temporal evolution of particle ejection velocity and trajectory. These results highlight the importance of scaled and repeatable laboratory experiments for an enhanced understanding of natural volcanic phenomena that bear direct observability. A closer link will enhance volcanic hazard assessment.

Design and Analyses of High Aspect Ratio Nozzles for Distributed Propulsion Acoustic Measurements

NASA Technical Reports Server (NTRS)

Dippold, Vance F., III

2016-01-01

A series of three convergent, round-to-rectangular high aspect ratio (HAR) nozzles were designed for acoustic testing at the NASA Glenn Research Center Nozzle Acoustic Test Rig (NATR). The HAR nozzles had exit area aspect ratios of 8:1, 12:1, and 16:1. The nozzles were designed to mimic a distributed propulsion system array with a slot nozzle. The nozzle designs were screened using Reynolds-Averaged Navier-Stokes (RANS) simulations. In addition to meeting the geometric constraints required for testing in the NATR, the HAR nozzles were designed to be free of flow features that would produce unwanted noise (e.g., flow separations) and to have uniform flow at the nozzle exit. Multiple methods were used to generate HAR nozzle designs. The final HAR nozzle designs were generated in segments using a computer code that parameterized each segment. RANS screening simulations showed that intermediate nozzle designs suffered flow separation, a normal shockwave at the nozzle exit (caused by an aerodynamic throat produced by boundary layer growth), and non-uniform flow at the nozzle exit. The RANS simulations showed that the final HAR nozzle designs were free of flow separations, but were not entirely successful at producing a fully uniform flow at the nozzle exit. The final designs suffered a pair of counter-rotating vortices along the outboard walls of the nozzle. The 16:1 aspect ratio HAR nozzle had the least uniform flow at the exit plane; the 8:1 aspect ratio HAR nozzles had a fairly uniform flow at the nozzle exit plane.

Computer program for design analysis of radial-inflow turbines

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1976-01-01

A computer program written in FORTRAN that may be used for the design analysis of radial-inflow turbines was documented. The following information is included: loss model (estimation of losses), the analysis equations, a description of the input and output data, the FORTRAN program listing and list of variables, and sample cases. The input design requirements include the power, mass flow rate, inlet temperature and pressure, and rotational speed. The program output data includes various diameters, efficiencies, temperatures, pressures, velocities, and flow angles for the appropriate calculation stations. The design variables include the stator-exit angle, rotor radius ratios, and rotor-exit tangential velocity distribution. The losses are determined by an internal loss model.

Progressing batch hydrolysis process

DOEpatents

Wright, J.D.

1985-01-10

A progressive batch hydrolysis process is disclosed for producing sugar from a lignocellulosic feedstock. It comprises passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with feed stock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feed stock to glucose. The cooled dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, serially fed through a plurality of pre-hydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose. The dilute acid stream containing glucose is cooled after it exits the last prehydrolysis reactor.

Progressing batch hydrolysis process

DOEpatents

Wright, John D.

1986-01-01

A progressive batch hydrolysis process for producing sugar from a lignocellulosic feedstock, comprising passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feedstock to glucose; cooling said dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, then feeding said dilute acid stream serially through a plurality of prehydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose; and cooling the dilute acid stream containing glucose after it exits the last prehydrolysis reactor.

Analytical and Experimental Study of Flow Through an Axial Turbine Stage with a Nonuniform Inlet Radial Temperature Profile

NASA Technical Reports Server (NTRS)

Schwab, J. R.; Stabe, R. G.; Whitney, W. J.

1983-01-01

Results are presented for a typical nonuniform inlet radial temperature profile through an advanced single-stage axial turbine and compared with the results obtained for a uniform profile. Gas temperature rises of 40 K to 95 K are predicted at the hub and tip corners at the trailing edges of the pressure surfaces in both the stator and rotor due to convection of hot fluid from the mean by the secondary flow. The inlet temperature profile is shown to be mixed out at the rotor exit survey plane (2.3 axial chords downstream of the rotor trailing edge) in both the analysis and the experiment. The experimental rotor exit angle profile for the nonuniform inlet temperature profile indicates underturning at the tip caused by increased clearance. Severe underturning also occurs at the mean, both with and without the nonuniform inlet temperature profile. The inviscid rotational flow code used in the analysis fails to predict the underturning at the mean, which may be caused by viscous effects.

Analytical and experimental study of flow through an axial turbine stage with a nonuniform inlet radial temperature profile

NASA Technical Reports Server (NTRS)

Schwab, J. R.; Stabe, R. G.; Whitney, W. J.

1983-01-01

Results are presented for a typical nonuniform inlet radial temperature profile through an advanced single-stage axial turbine and compared with the results obtained for a uniform profile. Gas temperature rises of 40 K to 95 K are predicted at the hub and tip corners at the trailing edges of the pressure surfaces in both the stator and rotor due to convection of hot fluid from the mean by the secondary flow. The inlet temperature profile is shown to be mixed out at the rotor exit survey plane (2.3 axial chords downstream of the rotor trailing edge) in both the analysis and the experiment. The experimental rotor exit angle profile for the nonuniform inlet temperature profile indicates underturning at the tip caused by increased clearance. Severe underturning also occurs at the mean, both with and without the nonuniform inlet temperature profile. The inviscid rotational flow code used in the analysis fails to predict the underturning at the mean, which may be caused by viscous effects. Previously announced in STAR as N83-27958

A Possible Strategy for the Use of Solar Climate Engineering

NASA Astrophysics Data System (ADS)

Ackerman, T. P.; Russotto, R. D.; Kravitz, B.

2016-12-01

The Paris accord signals an international effort to hold global temperature change below 2°C above pre-industrial levels, raising the question of what role solar climate engineering (SCE) might play in meeting this objective. However, avoiding continuing, long-term application of SCE with an ever increasing magnitude requires an "exit strategy", i. e., a plan to phase out SCE by removing stabilizing and removing CO2. Here we present results from a series of climate model runs that combine both CO2 and SCE transient forcings over a 200-year period (2000 to 2200). Our results confirm past results that maintaining both global surface air temperature (TA) and precipitation (P) at baseline levels is not feasible. They also demonstrate a quasi-linear relationship between changes in SCE and changes in P. Zonally-averaged changes in TA show, as expected, polar amplification of warming, but that enhancement scales uniformly with the change in global TA. We draw several conclusions from our results: (1) There are plausible scenarios in which SCE can be part of an integrated strategy to meet the temperature goals of the Paris accord. (2) Applying transient forcings can be used to maintain some, but not all, globally-averaged climate system variables (such as TA or P) at a prescribed baseline level. That globally-averaged stability, however, is achieved by averaging over changes in spatial distributions. These spatial changes create difficult issues regarding prediction of regional climate changes due to SCE and potential impacts on regional societies. (3) Our inability to predict interannual climate variability on the annual-to-decadal time scale suggests that it may take a decade or more to provide reliable detection and attribution of the global climate impacts of SCE following its inception (the so-called time of emergence). Furthermore, it will take much longer to determine regional impacts.

CHARGE MEASUREMENTS OF PARTICLES EXITING ELECTROSTATIC PRECIPITATORS

EPA Science Inventory

The report gives results of an investigation of particle charging in positive and negative corona discharge as a function of temperature from 38 to 343C in order to establish, especially at hot-side electrostatic precipitator (ESP) temperatures, the relative effectiveness of the ...

40 CFR 63.1415 - Monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... thermocouple, ultra-violet beam sensor, or infrared sensor) capable of continuously detecting the presence of a... an absorber is used, a scrubbing liquid temperature monitoring device and a specific gravity... condenser exit temperature (product side) monitoring device equipped with a continuous recorder is required...

40 CFR 63.1415 - Monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... thermocouple, ultra-violet beam sensor, or infrared sensor) capable of continuously detecting the presence of a... an absorber is used, a scrubbing liquid temperature monitoring device and a specific gravity... condenser exit temperature (product side) monitoring device equipped with a continuous recorder is required...

40 CFR 63.1415 - Monitoring requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... thermocouple, ultra-violet beam sensor, or infrared sensor) capable of continuously detecting the presence of a...) Where an absorber is used, a scrubbing liquid temperature monitoring device and a specific gravity... condenser exit temperature (product side) monitoring device equipped with a continuous recorder is required...

Effect of Velocity and Temperature Distribution at the Hole Exit on Film Cooling of Turbine Blades

NASA Technical Reports Server (NTRS)

Garg, V. K.; Gaugler, R. E.

1997-01-01

An existing three-dimensional Navier-Stokes code (Arnone et al, 1991), modified Turbine Branch, to include film cooling considerations (Garg and Gaugler, 1994), has been used to study the effect of coolant velocity and temperature distribution at the hole exit on the heat transfer coefficient on three film-cooled turbine blades, namely, the C3X vane, the VKI rotor, and the ACE rotor. Results are also compared with the experimental data for all the blades. Moreover, Mayle's transition criterion (1991), Forest's model for augmentation of leading edge heat transfer due to free-stream turbulence (1977), and Crawford's model for augmentation of eddy viscosity due to film cooling (Crawford et al, 1980) are used. Use of Mayle's and Forest's models is relevant only for the ACE rotor due to the absence of showerhead cooling on this rotor. It is found that, in some cases, the effect of distribution of coolant velocity and temperature at the hole exit can be as much as 60 percent on the heat transfer coefficient at the blade suction surface, and 50 percent at the pressure surface. Also, different effects are observed on the pressure and suction surface depending upon the blade as well as upon the hole shape, conical or cylindrical.

Species and temperature measurement in H2/O2 rocket flow fields by means of Raman scattering diagnostics

NASA Technical Reports Server (NTRS)

Degroot, Wim A.; Weiss, Jonathan M.

1992-01-01

Validation of Computational Fluid Dynamics (CFD) codes developed for prediction and evaluation of rocket performance is hampered by a lack of experimental data. Non-intrusive laser based diagnostics are needed to provide spatially and temporally resolved gas dynamic and fluid dynamic measurements. This paper reports the first non-intrusive temperature and species measurements in the plume of a 110 N gaseous hydrogen/oxygen thruster at and below ambient pressures, obtained with spontaneous Raman spectroscopy. Measurements at 10 mm downstream of the exit plane are compared with predictions from a numerical solution of the axisymmetric Navier-Stokes and species transport equations with chemical kinetics, which fully model the combustor-nozzle-plume flowfield. The experimentally determined oxygen number density at the centerline at 10 mm downstream of the exit plane is four times that predicted by the model. The experimental number density data fall between those numerically predicted for the exit and 10 mm downstream planes in both magnitude and radial gradient. The predicted temperature levels are within 10 to 15 percent of measured values. Some of the discrepancies between experimental data and predictions result from not modeling the three dimensional core flow injection mixing process, facility back pressure effects, and possible diffuser-thruster interactions.

SU-F-T-258: Efficacy of Exit Fluence-Based Dose Calculation for Prostate Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siebers, J; Gardner, J; Neal, B

Purpose: To investigate the efficacy of exit-fluence-based dose computation for prostate radiotherapy by determining if it estimates true dose more accurately than the original planning dose. Methods: Virtual exit-fluencebased dose computation was performed for 19 patients, each with 9–12 repeat CT images. For each patient, a 78 Gy treatment plan was created utilizing 5 mm CTV-to-PTV and OAR-to-PRV margins. A Monte Carlo framework was used to compute dose and exit-fluence images for the planning image and for each repeat CT image based on boney-anatomyaligned and prostate-centroid-aligned CTs. Identical source particles were used for the MC dose-computations on the planning andmore » repeat CTs to maximize correlation. The exit-fluence-based dose and image were computed by multiplying source particle weights by FC(x,y)=FP(x,y)/FT(x,y), where (x,y) are the source particle coordinates projected to the exit-fluence plane and we denote the dose/fluence from the plan by (DP,FP), from the repeat-CT as (DT,FT), and the exit-fluence computation by (DFC,FFC). DFC mimics exit-fluence backprojection through the planning image as FT=FFC. Dose estimates were intercompared to judge the efficacy of exit-fluence-based dose computation. Results: Boney- and prostate-centroid aligned results are combined as there is no statistical difference between them, yielding 420 dose comparisons per dose-volume metric. DFC is more accurate than DP for 46%, 33%, and 44% of cases in estimating CTV D98, D50, and D2 respectively. DFC improved rectum D50 and D2 estimates 54% and 49% respectively and bladder D50 and D2 47 and 49% respectively. While averaged over all patients and images DFC and DP were within 3.1% of DT, they differed from DT by as much as 22% for GTV D98, 71% for the Bladder D50, 17% for Bladder D2, 19% for Rectum D2. Conclusion: Exit-fluence based dose computations infrequently improve CTV or OAR dose estimates and should be used with caution. Research supported in part by Varian Medical Systems.« less

Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

NASA Astrophysics Data System (ADS)

Hinson, David P.; Linscott, Ivan; Young, Leslie; Stern, S. Alan; Bird, Mike; Ennico, Kimberly; Gladstone, Randy; Olkin, Catherine B.; Pätzold, Martin; Strobel, Darrell F.; Summers, Michael; Tyler, G. Leonard; Weaver, Harold A.; Woods, Will; New Horizons Science Team

2016-10-01

The reconnaissance of the Pluto System by New Horizons in July 2015 included a radio occultation at Pluto. The observation was performed with signals transmitted simultaneously by four antennas of the NASA Deep Space Network, two at the Goldstone complex in California and two at the Canberra complex in Australia. Each antenna radiated 20 kW without modulation at a wavelength of 4.17 cm. New Horizons received the four signals with its 2.1-m high-gain antenna, where the signals were split into pairs and processed independently by two identical REX radio science instruments. Each REX relied on a different ultra-stable oscillator as its frequency reference. The signals were digitized and filtered, and the data samples were stored on the spacecraft for later transmission to Earth. Six months elapsed before all data had arrived on the ground, and the results reported here are the first to utilize the complete set of observations. Pluto's tenuous atmosphere is a significant challenge for radio occultation sounding, which led us to develop a specialized method of analysis. We began by calibrating each signal to remove effects not associated with Pluto's atmosphere, including the diffraction pattern from Pluto's surface. We reduced the noise and increased our sensitivity to the atmosphere by averaging the results from the four signals, while using other combinations of the signals to characterize the noise. We then retrieved profiles of number density, pressure, and temperature from the averaged phase profiles at both occultation entry and exit. Finally, we used a combination of analytical methods and Monte Carlo simulations to determine the accuracy of the measurements. The REX profiles provide the first direct measure of the surface pressure and temperature structure in Pluto's lower atmosphere. There are significant differences between the structure at entry (193.5°E, 17.0°S, sunset) and exit (15.7°E, 15.1°N, sunrise), which arise from spatial variations in surface composition coupled with the diurnal cycle of condensation and sublimation of nitrogen. This work is supported by the NASA New Horizons Mission.

Association of rheumatic diseases with early exit from paid employment in Portugal.

PubMed

Laires, Pedro A; Gouveia, Miguel

2014-04-01

To examine the association between rheumatic diseases (RD) and other chronic morbidity with early exit from paid employment in the Portuguese population. The study population consisted of all people between 50 and 64 years of age (3,762 men and 4,241 women) who participated in the Portuguese National Health Survey, conducted in 2005/2006. Data were collected on demographics, ill-health, lifestyle, and socioeconomic factors. Logistic regression was used to estimate the isolated effect of rheumatic diseases and other chronic diseases on the likelihood of exit from paid employment. At the time of the survey, 45.1 % of the Portuguese population with ages between 50 and 64 years old were not employed. In the nonemployed population, 31.6 % self-reported "poor" to "very poor" health, whereas 16.4 % did so in the employed population. A larger average number of major chronic diseases per capita were also found in those not employed (1.9 vs. 1.4, p < 0.001). In the multivariate models, chronic diseases were associated with early exit from paid employment. In particular, rheumatic diseases were more prevalent (43.4 vs. 32.1 %) and associated with early exit from work (OR 1.31; CI 1.12-1.52, p = 0.001). This study suggests an association between RD and other major chronic diseases with early exit from paid employment in Portugal. Thus, health and social protection policies should target these chronic disorders in order to better address sustainability issues and social protection effectiveness.

Description and calibration of the Langley Hypersonic CF4 tunnel: A facility for simulating low gamma flow as occurs for a real gas

NASA Technical Reports Server (NTRS)

Midden, Raymond E.; Miller, Charles G., III

1985-01-01

The Langley Hypersonic CF4 Tunnel is a Mach 6 facility which simulates an important aspect of dissociative real-gas phenomena associated with the reentry of blunt vehicles, i.e., the decrease in the ratio of specific heats (gamma) that occurs within the shock layer of the vehicle. A general description of this facility is presented along with a discussion of the basic components, instrumentation, and operating procedure. Pitot-pressure surveys were made at the nozzle exit and downstream of the exit for reservoir temperatures from 1020 to 1495 R and reservoir pressures from 1000 to 2550 psia. A uniform test core having a diameter of circa 11 in. (0.55 times the nozzle-exit diameter) exists at the maximum value of reservoir pressure and temperature. The corresponding free-stream Mach number is 5.9, the unit Reynolds number is 4 x 10 to the 5th power per foot, the ratio of specific heats immediately behind a normal shock is 1.10, and the normal-shock density ratio is 12.6. When the facility is operated at reservoir temperatures below 1440 R, irregularities occur in the pitot-pressure profile within a small region about the nozzle centerline. These variations in pitot pressure indicate the existence of flow distrubances originating in the upstream region of the nozzle. This necessitates testing models off centerline in the uniform flow between the centerline region and either the nozzle boundary layer or the lip shock originating at the nozzle exit. Samples of data obtained in this facility with various models are presented to illustrate the effect of gamma on flow conditions about the model and the importance of knowing the magnitude of this effect.

Clinical implementation of an exit detector-based dose reconstruction tool for helical tomotherapy delivery quality assurance.

PubMed

Deshpande, Shrikant; Xing, Aitang; Metcalfe, Peter; Holloway, Lois; Vial, Philip; Geurts, Mark

2017-10-01

The aim of this study was to validate the accuracy of an exit detector-based dose reconstruction tool for helical tomotherapy (HT) delivery quality assurance (DQA). Exit detector-based DQA tool was developed for patient-specific HT treatment verification. The tool performs a dose reconstruction on the planning image using the sinogram measured by the HT exit detector with no objects in the beam (i.e., static couch), and compares the reconstructed dose to the planned dose. Vendor supplied (three "TomoPhant") plans with a cylindrical solid water ("cheese") phantom were used for validation. Each "TomoPhant" plan was modified with intentional multileaf collimator leaf open time (MLC LOT) errors to assess the sensitivity and robustness of this tool. Four scenarios were tested; leaf 32 was "stuck open," leaf 42 was "stuck open," random leaf LOT was closed first by mean values of 2% and then 4%. A static couch DQA procedure was then run five times (once with the unmodified sinogram and four times with modified sinograms) for each of the three "TomoPhant" treatment plans. First, the original optimized delivery plan was compared with the original machine agnostic delivery plan, then the original optimized plans with a known modification applied (intentional MLC LOT error) were compared to the corresponding error plan exit detector measurements. An absolute dose comparison between calculated and ion chamber (A1SL, Standard Imaging, Inc., WI, USA) measured dose was performed for the unmodified "TomoPhant" plans. A 3D gamma evaluation (2%/2 mm global) was performed by comparing the planned dose ("original planned dose" for unmodified plans and "adjusted planned dose" for each intentional error) to exit detector-reconstructed dose for all three "Tomophant" plans. Finally, DQA for 119 clinical (treatment length <25 cm) and three cranio-spinal irradiation (CSI) plans were measured with both the ArcCHECK phantom (Sun Nuclear Corp., Melbourne, FL, USA) and the exit detector DQA tool to assess the time required for DQA and similarity between two methods. The measured ion chamber dose agreed to within 1.5% of the reconstructed dose computed by the exit detector DQA tool on a cheese phantom for all unmodified "Tomophant" plans. Excellent agreement in gamma pass rate (>95%) was observed between the planned and reconstructed dose for all "Tomophant" plans considered using the tool. The gamma pass rate from 119 clinical plan DQA measurements was 94.9% ± 1.5% and 91.9% ± 4.37% for the exit detector DQA tool and ArcCHECK phantom measurements (P = 0.81), respectively. For the clinical plans (treatment length <25 cm), the average time required to perform DQA was 24.7 ± 3.5 and 39.5 ± 4.5 min using the exit detector QA tool and ArcCHECK phantom, respectively, whereas the average time required for the 3 CSI treatments was 35 ± 3.5 and 90 ± 5.2 min, respectively. The exit detector tool has been demonstrated to be faster for performing the DQA with equivalent sensitivity for detecting MLC LOT errors relative to a conventional phantom-based QA method. In addition, comprehensive MLC performance evaluation and features of reconstructed dose provide additional insight into understanding DQA failures and the clinical relevance of DQA results. © 2017 American Association of Physicists in Medicine.

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2010 CFR

2010-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2012 CFR

2012-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2011 CFR

2011-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2010 CFR

2010-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

Plasma Potential and Langmuir Probe Measurements in the Near-field Plume of the NASA-457Mv2 Hall Thruster

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Huang, Wensheng; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

2012-01-01

In order to further the design of future high-power Hall thrusters and provide experimental validation for ongoing modeling efforts, plasma potential and Langmuir probe measurements were performed on the 50-kW NASA-457Mv2. An electrostatic probe array comprised of a near-field Faraday probe, single Langmuir probe, and emissive probe was used to interrogate the near-field plume from approximately 0.1 - 2.0 mean thruster diameters downstream of the thruster exit plane at the following operating conditions: 300 V, 400 V and 500 V at 30 kW and 500 V at 50 kW. Results have shown that the acceleration zone is limited to within 0.4 mean thruster diameters of the exit plane while the high-temperature region is limited to 0.25 mean thruster diameters from the exit plane at all four operating conditions. Maximum plasma potentials in the near-field at 300 and 400 V were approximately 50 V with respect to cathode potential, while maximum electron temperatures varied from 24 - 32 eV, depending on operating condition. Isothermal lines at all operating conditions were found to strongly resemble the magnetic field topology in the high-temperature regions. This distribution was found to create regions of high temperature and low density near the magnetic poles, indicating strong, thick sheath formation along these surfaces. The data taken from this study are considered valuable for future design as well as modeling validation.

Core compressor exit stage study. 1: Aerodynamic and mechanical design

NASA Technical Reports Server (NTRS)

Burdsall, E. A.; Canal, E., Jr.; Lyons, K. A.

1979-01-01

The effect of aspect ratio on the performance of core compressor exit stages was demonstrated using two three stage, highly loaded, core compressors. Aspect ratio was identified as having a strong influence on compressors endwall loss. Both compressors simulated the last three stages of an advanced eight stage core compressor and were designed with the same 0.915 hub/tip ratio, 4.30 kg/sec (9.47 1bm/sec) inlet corrected flow, and 167 m/sec (547 ft/sec) corrected mean wheel speed. The first compressor had an aspect ratio of 0.81 and an overall pressure ratio of 1.357 at a design adiabatic efficiency of 88.3% with an average diffusion factor or 0.529. The aspect ratio of the second compressor was 1.22 with an overall pressure ratio of 1.324 at a design adiabatic efficiency of 88.7% with an average diffusion factor of 0.491.

Measurement of Initial Conditions at Nozzle Exit of High Speed Jets

NASA Technical Reports Server (NTRS)

Panda, J.; Zaman, K. B. M. Q.; Seasholtz, R. G.

2004-01-01

The time averaged and unsteady density fields close to the nozzle exit (0.1 less than or = x/D less than or = 2, x: downstream distance, D: jet diameter) of unheated free jets at Mach numbers of 0.95, 1.4, and 1.8 were measured using a molecular Rayleigh scattering based technique. The initial thickness of shear layer and its linear growth rate were determined from time-averaged density survey and a modeling process, which utilized the Crocco-Busemann equation to relate density profiles to velocity profiles. The model also corrected for the smearing effect caused by a relatively long probe length in the measured density data. The calculated shear layer thickness was further verified from a limited hot-wire measurement. Density fluctuations spectra, measured using a two-Photomultiplier-tube technique, were used to determine evolution of turbulent fluctuations in various Strouhal frequency bands. For this purpose spectra were obtained from a large number of points inside the flow; and at every axial station spectral data from all radial positions were integrated. The radially-integrated fluctuation data show an exponential growth with downstream distance and an eventual saturation in all Strouhal frequency bands. The initial level of density fluctuations was calculated by extrapolation to nozzle exit.

Radial magnetic compression in the expelled jet of a plasma deflagration accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loebner, Keith T. K., E-mail: kloebner@stanford.edu; Underwood, Thomas C.; Mouratidis, Theodore

2016-02-29

A spectroscopic study of a pulsed plasma deflagration accelerator is carried out that confirms the existence of a strong compression in the emerging jet at the exit plane of the device. An imaging spectrometer is used to collect broadened Hα emission from a transaxial slice of the emerging jet at high spatial resolution, and the radial plasma density profile is computed from Voigt fits of the Abel inverted emissivity profiles. The plasma temperature, determined via Doppler broadening of impurity line emission, is compared against the temperature predictions of a radial magnetohydrodynamic equilibrium model applied to the measured density profiles. Empiricalmore » scaling laws developed for the plasma density, combined with the measured and predicted temperatures, indicate that a radially equilibrated Z-pinch is formed within the expelled plasma jet at the exit plane during the deflagration process.« less

Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

NASA Astrophysics Data System (ADS)

Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

2016-06-01

Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

Composting on Mars or the Moon: II. Temperature feedback control with top-wise introduction of waste material and air

NASA Technical Reports Server (NTRS)

Finstein, M. S.; Hogan, J. A.; Sager, J. C.; Cowan, R. M.; Strom, P. F.; Janes, H. W. (Principal Investigator)

1999-01-01

Whereas Earth-based composting reactors that effectively control the process are batch operations with bottom-to-top airflow, in extraterrestrial application both the fresh waste and the air need to be introduced from above. Stabilized compost and used air would exit below. This materials flow pattern permits the addition of waste whenever generated, obviating the need for multiple reactors, and the incorporation of a commode in the lid. Top loading in turn dictates top-down aeration, so that the most actively decomposing material (greatest need for heat removal and O2 replenishment) is first encountered. This novel material and aeration pattern was tested in conjunction with temperature feedback process control. Reactor characteristics were: working, volume, 0.15 m3; charge, 2 kg dry biomass per day (comparable to a 3-4 person self-sufficient bioregenerative habitat); retention time, 7 days. Judging from temperature profile, O2 level, air usage, pressure head loss, moisture, and odor, the system was effectively controlled over a 35-day period. Dry matter disappearance averaged 25% (10-42%). The compost product was substantially, though not completely, stabilized. This demonstrates the compatibility of top-wise introduction of waste and air with temperature feedback process control.

Composting on Mars or the Moon: II. Temperature feedback control with top-wise introduction of waste material and air.

PubMed

Finstein, M S; Hogan, J A; Sager, J C; Cowan, R M; Strom, P F

1999-01-01

Whereas Earth-based composting reactors that effectively control the process are batch operations with bottom-to-top airflow, in extraterrestrial application both the fresh waste and the air need to be introduced from above. Stabilized compost and used air would exit below. This materials flow pattern permits the addition of waste whenever generated, obviating the need for multiple reactors, and the incorporation of a commode in the lid. Top loading in turn dictates top-down aeration, so that the most actively decomposing material (greatest need for heat removal and O2 replenishment) is first encountered. This novel material and aeration pattern was tested in conjunction with temperature feedback process control. Reactor characteristics were: working, volume, 0.15 m3; charge, 2 kg dry biomass per day (comparable to a 3-4 person self-sufficient bioregenerative habitat); retention time, 7 days. Judging from temperature profile, O2 level, air usage, pressure head loss, moisture, and odor, the system was effectively controlled over a 35-day period. Dry matter disappearance averaged 25% (10-42%). The compost product was substantially, though not completely, stabilized. This demonstrates the compatibility of top-wise introduction of waste and air with temperature feedback process control.

Combustion efficiency of a premixed continuous flow combustor

NASA Technical Reports Server (NTRS)

Anand, M. S.; Gouldin, F. C.

1985-01-01

Exhaust gas temperature, velocity, and composition measurements at various radial locations at the combustor exit are presented for a swirling-flow continuous combustor of a confined concentric jet configuration operating on premixed propane or methane and air. The main objective of the study is to determine the effect of fuel substitution and of changes in outer flow swirl conditions on the combustor performance. It is found that there is no difference in observed properties for propane and methane firing; the use of either of the fuels results in nearly the same exit temperature and velocity profiles and the same efficiency for a given operating condition. A mechanism for combustion is proposed which explains qualitatively the changes in efficiency and pollutant emissions observed with changing swirl.

Theoretical Performance of Liquid Hydrogen with Liquid Oxygen as a Rocket Propellant

NASA Technical Reports Server (NTRS)

Gordon, Sanford; McBride, Bonnie J.

1959-01-01

Theoretical rocket performance for both equilibrium and frozen composition during expansion was calculated for the propellant combination liquid hydrogen and liquid oxygen at four chamber pressures (60, 150, 300, and 600 lb/sq in. abs) and a wide range of pressure ratios (1 to 4000) and oxidant-fuel ratios (1.190 to 39.683). Data are given to estimate performance parameters at chamber pressures other than those for which data are tabulated. The parameters included are specific impulse, specific impulse in vacuum, combustion-chamber temperature, nozzle-exit temperature, molecular weight, molecular-weight derivatives, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, isentropic exponent, viscosity, thermal conductivity, Mach number, and equilibrium gas compositions.

Characteristics of Gaseous Diffusion Flames with High Temperature Combustion Air in Microgravity

NASA Technical Reports Server (NTRS)

Ghaderi, M.; Gupta, A. K.

2003-01-01

The characteristics of gaseous diffusion flames have been obtained using high temperature combustion air under microgravity conditions. The time resolved flame images under free fall microgravity conditions were obtained from the video images obtained. The tests results reported here were conducted using propane as the fuel and about 1000 C combustion air. The burner included a 0.686 mm diameter central fuel jet injected into the surrounding high temperature combustion air. The fuel jet exit Reynolds number was 63. Several measurements were taken at different air preheats and fuel jet exit Reynolds number. The resulting hybrid color flame was found to be blue at the base of the flame followed by a yellow color flame. The length and width of flame during the entire free fall conditions has been examined. Also the relative flame length and width for blue and yellow portion of the flame has been examined under microgravity conditions. The results show that the flame length decreases and width increases with high air preheats in microgravity condition. In microgravity conditions the flame length is larger with normal temperature combustion air than high temperature air.

[A new kinematics method of determing elbow rotation axis and evaluation of its feasibility].

PubMed

Han, W; Song, J; Wang, G Z; Ding, H; Li, G S; Gong, M Q; Jiang, X Y; Wang, M Y

2016-04-18

To study a new positioning method of elbow external fixation rotation axis, and to evaluate its feasibility. Four normal adult volunteers and six Sawbone elbow models were brought into this experiment. The kinematic data of five elbow flexion were collected respectively by optical positioning system. The rotation axes of the elbow joints were fitted by the least square method. The kinematic data and fitting results were visually displayed. According to the fitting results, the average moving planes and rotation axes were calculated. Thus, the rotation axes of new kinematic methods were obtained. By using standard clinical methods, the entrance and exit points of rotation axes of six Sawbone elbow models were located under X-ray. And The kirschner wires were placed as the representatives of rotation axes using traditional positioning methods. Then, the entrance point deviation, the exit point deviation and the angle deviation of two kinds of located rotation axes were compared. As to the four volunteers, the indicators represented circular degree and coplanarity of elbow flexion movement trajectory of each volunteer were both about 1 mm. All the distance deviations of the moving axes to the average moving rotation axes of the five volunteers were less than 3 mm. All the angle deviations of the moving axes to the average moving rotation axes of the five volunteers were less than 5°. As to the six Sawbone models, the average entrance point deviations, the average exit point deviations and the average angle deviations of two different rotation axes determined by two kinds of located methods were respectively 1.697 2 mm, 1.838 3 mm and 1.321 7°. All the deviations were very small. They were all in an acceptable range of clinical practice. The values that represent circular degree and coplanarity of volunteer's elbow single curvature movement trajectory are very small. The result shows that the elbow single curvature movement can be regarded as the approximate fixed axis movement. The new method can replace the traditional method in accuracy. It can make up the deficiency of the traditional fixed axis method.

Development of the cascade inertial-confinement-fusion reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitts, J.H.

Caqscade, originally conceived as a football-shaped, steel-walled reactor containing a Li/sub 2/O granule blanket, is now envisaged as a double-cone-shaped reactor containing a two-layered (three-zone) flowing blanket of BeO and LiAlO/sub 2/ granules. Average blanket exit temperature is 1670 K and gross plant efficiency (net thermal conversion efficiency) using a Brayton cycle is 55%. The reactor has a low-activation SiC-tiled wall. It rotates at 50 rpm, and the granules are transported to the top of the heat exchanger using their peripheral speed; no conveyors or lifts are required. The granules return to the reactor by gravity. After considerable analysis andmore » experimentation, we continue to regard Cascade as a promising reactor concept with the advantages of safety, efficiency, and low activation.« less

Development of the cascade inertial-confinement-fusion reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitts, J.H.

Cascade, originally conceived as a football-shaped, steel-walled reactor containing a Li/sub 2/O granule blanket, is now envisaged as a double-cone-shaped reactor containing a two-layered (three-zone) flowing blanket of BeO and LiAlO/sub 2/ granules. Average blanket exit temperature is 1670/sup 0/K and gross plant efficiency (net thermal conversion efficiency) using a Brayton cycle is 55%. The reactor has a low-activation SiC-tiled wall. It rotates at 50 rpm, and the granules are transported to the top of the heat exchanger using their peripheral speed; no conveyors or lifts are required. The granules return to the reactor by gravity. After considerable analysis andmore » experimentation, we continue to regard Cascade as a promising reactor concept with the advantages of safety, efficiency, and low activation.« less

Pretest analysis document for Semiscale Test S-FS-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, T.H.

This report documents the pretest analysis calculation completed with the RELAP5/MOD2/CY21 code for Semiscale Test S-FS-1. The test will simulate the double-ended offset shear of the main steam line at the exit of the broken loop steam generator (downstream of the flow restrictor) and the subsequent plant recovery. The recovery portion of the test consists of a plant stabilization phase and a plant cooldown phase. The recovery procedures involve normal charging/letdown operation, pressurizer heater operation, secondary steam and feed of the unaffected steam generator, and pressurizer auxiliary spray. The test will be terminated after the unaffected steam generator and pressurizermore » pressures and liquid levels are stable, and the average priamry fluid temperature is stable at about 480 K (405/sup 0/F) for at least 10 minutes.« less

CALUTRON ION SOURCE

DOEpatents

Lofgren, E.J.

1959-02-17

An improvement is described in ion source mechanisms whereby the source structure is better adapted to withstanid the ravages of heat, erosion, and deterioration concomitant with operation of an ion source of the calutron type. A pair of molybdenum plates define the exit opening of the arc chamber and are in thermal contact with the walls of the chamber. These plates are maintained at a reduced temperature by a pair of copper blocks in thermal conducting contact therewith to form subsequent diverging margins for the exit opening.

Flow-through pretreatment of lignocellulosic biomass with inorganic nanoporous membranes

DOEpatents

Bhave, Ramesh R.; Lynd, Lee; Shao, Xiongjun

2018-04-03

A process for the pretreatment of lignocellulosic biomass is provided. The process generally includes flowing water through a pretreatment reactor containing a bed of particulate ligno-cellulosic biomass to produce a pressurized, high-temperature hydrolyzate exit stream, separating solubilized compounds from the hydrolyzate exit stream using an inorganic nanoporous membrane element, fractionating the retentate enriched in solubilized organic components and recycling the permeate to the pretreatment reactor. The pretreatment process provides solubilized organics in concentrated form for the subsequent conversion into biofuels and other chemicals.

Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

NASA Astrophysics Data System (ADS)

Endo, Keita; Katsuragi, Hiroaki

2017-06-01

Two-dimensional granular discharge flow driven by gravity under the influence of an obstacle is experimentally investigated. A horizontal exit of width W is opened at the bottom of vertical Hele-Shaw cell filled with stainless-steel particles to start the discharge flow. In this experiment, a circular obstacle is placed in front of the exit. Thus, the distance between the exit and obstacle L is also an important parameter. During the discharge, granular-flow state is acquired by a high-speed camera. The bulk discharge-flow rate is also measured by load cell sensors. The obtained high-speed-image data are analyzed to clarify the particle-level granular-flow dynamics. Using the measured data, we find that the obstacle above the exit affects the granular- flow field. Specifically, the existence of obstacle results in large horizontal granular temperature and small packing fraction. This tendency becomes significant when L is smaller than approximately 6Dg when W ≃ 4Dg, where Dg is diameter of particles.

Simultaneous high-speed gas property measurements at the exhaust gas recirculation cooler exit and at the turbocharger inlet of a multicylinder diesel engine using diode-laser-absorption spectroscopy.

PubMed

Jatana, Gurneesh S; Magee, Mark; Fain, David; Naik, Sameer V; Shaver, Gregory M; Lucht, Robert P

2015-02-10

A diode-laser-absorption-spectroscopy-based sensor system was used to perform high-speed (100 Hz to 5 kHz) measurements of gas properties (temperature, pressure, and H(2)O vapor concentration) at the turbocharger inlet and at the exhaust gas recirculation (EGR) cooler exit of a diesel engine. An earlier version of this system was previously used for high-speed measurements of gas temperature and H(2)O vapor concentration in the intake manifold of the diesel engine. A 1387.2 N m tunable distributed feedback diode laser was used to scan across multiple H(2)O absorption transitions, and the direct absorption signal was recorded using a high-speed data acquisition system. Compact optical connectors were designed to conduct simultaneous measurements in the intake manifold, the EGR cooler exit, and the turbocharger inlet of the engine. For measurements at the turbocharger inlet, these custom optical connectors survived gas temperatures as high as 800 K using a simple and passive arrangement in which the temperature-sensitive components were protected from high temperatures using ceramic insulators. This arrangement reduced system cost and complexity by eliminating the need for any active water or oil cooling. Diode-laser measurements performed during steady-state engine operation were within 5% of the thermocouple and pressure sensor measurements, and within 10% of the H(2)O concentration values derived from the CO(2) gas analyzer measurements. Measurements were also performed in the engine during transient events. In one such transient event, where a step change in fueling was introduced, the diode-laser sensor was able to capture the 30 ms change in the gas properties; the thermocouple, on the other hand, required 7.4 s to accurately reflect the change in gas conditions, while the gas analyzer required nearly 600 ms. To the best of our knowledge, this is the first implementation of such a simple and passive arrangement of high-temperature optical connectors as well as the first documented application of diode-laser absorption for high-speed gas dynamics measurements in the turbocharger inlet and EGR cooler exit of a diesel engine.

Velocity and pressure characteristics of a model SSME high pressure fuel turbopump

NASA Technical Reports Server (NTRS)

Tse, D. G-N.; Sabnis, J. S.; Mcdonald, H.

1991-01-01

Under the present effort an experiment rig has been constructed, an instrumentation package developed and a series of mean and rms velocity and pressure measurements made in a turbopump which modelled the first stage of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump. The rig was designed so as to allow initial experiments with a single configuration consisting of a bell-mouth inlet, a flight impeller, a vaneless diffuser and a volute. Allowance was made for components such as inlet guide vanes, exit guide vanes, downstream pumps, etc. to be added in future experiments. This flexibility will provide a clear baseline set of experiments and allow evaluation in later experiments of the effect of adding specific components upon the pump performance properties. The rotational speed of the impeller was varied between 4260 and 7680 rpm which covered the range of scaled SSME rotation speeds when due allowance is made for the differing stagnation temperature, model to full scale. The results at the inlet obtained with rotational speeds of 4260, 6084 and 7680 rpm showed that the axial velocity at the bell-mouth inlet remained roughly constant at 2.2 of the bulk velocity at the exit of the turbopump near the center of the inlet, but it decreased rapidly with increasing radius at all three speeds. Reverse flow occurred at a radius greater than 0.9 R for all three speeds and the maximum negative velocity reduced from 1.3 of the bulk velocity at the exit of the turbopump at 4260 rpm to 0.35 at 7680 rpm, suggesting that operating at a speed closer to the design condition of 8700 rpm improved the inlet characteristics. The reverse flow caused positive prerotation at the impeller inlet which was negligibly small near the center but reached 0.7 of the impeller speed at the outer annulus. The results in the diffuser and the volute obtained at 7680 rpm show that the hub and shroud walls of the diffuser were characterized by regions of transient reverse flow with negative revolution-averaged velocity of 8 percent of the maximum forward revolution-averaged velocity at the center of the diffuser passage near the shroud wall.

Comparison of native versus nonnative English-speaking nurses on critical thinking assessments at entry and exit.

PubMed

Whitehead, Tanya D

2006-01-01

Diversity of language among healthcare employees and nursing students is growing as diversity increases among the general population. Institutions have begun to develop systems to accommodate diversity and to assimilate workers. One barrier to nonnative English-speaking nurse hires may be posed by readiness for the licensure exam and the critical thinking assessments that are now an expected outcome of nursing programs, and act as a gatekeeper to graduation and to employment. To assist in preparing for high-stakes testing, the Assessment Technologies Institute Critical Thinking Assessment was developed in compliance with credentialing bodies' educational outcomes criteria. This pilot study of 209 nursing students was designed to reveal any possible language bias that might act as a barrier to nonnative English speakers. Nursing students were entered as whole classes to the study to control for selection bias. A sample representative of national nursing enrollment was obtained from 21 universities, with 192 (92%) native English-speaking students and 17 (8%) nonnative English speakers participating in the study. All students were given the Assessment Technologies Institute Critical Thinking Assessment at entry and exit to their nursing program. Average scores on entry were 66% for nonnative speakers and 72% for native speakers. At exit, the nonnative speakers had closed the gap in academic outcomes. They had an average score of 72% compared to 73% for native speakers. The study found that the slight differences between the native and nonnative speakers on 2 exit outcome measures-National Council licensure examination (NCLEX-RN) pass rates and Critical Thinking Assessment-were not statistically significant, demonstrating that nonnative English speakers achieved parity with native English-speaking peers on the Critical Thinking Assessment tool, which is often believed to be related to employment readiness.

Introduction of frictional and turning function for pedestrian outflow with an obstacle.

PubMed

Yanagisawa, Daichi; Kimura, Ayako; Tomoeda, Akiyasu; Nishi, Ryosuke; Suma, Yushi; Ohtsuka, Kazumichi; Nishinari, Katsuhiro

2009-09-01

In this paper, two important factors which affect the pedestrian outflow at a bottleneck significantly are studied in detail to analyze the effect of an obstacle setup in front of an exit. One is a conflict at an exit when pedestrians evacuate from a room. We use floor field model for simulating such behavior, which is a well-studied pedestrian model using cellular automata. The conflicts have been taken into account by the friction parameter. However, the friction parameter so far is a constant and does not depend on the number of the pedestrians conflicting at the same time. Thus, we have improved the friction parameter by the frictional function, which is a function of the number of the pedestrians involved in the conflict. Second, we have presented the cost of turning of pedestrians at the exit. Since pedestrians have inertia, their walking speeds decrease when they turn and the pedestrian outflow decreases. The validity of the extended model, which includes the frictional function and the turning function, is supported by the comparison of a mean-field theory and real experiments. We have observed that the pedestrian flow increases when we put an obstacle in front of an exit in our real experiments. The analytical results clearly explains the mechanism of the effect of the obstacle, i.e., the obstacle blocks pedestrians moving to the exit and decreases the average number of pedestrians involved in the conflict. We have also found that an obstacle works more effectively when we shift it from the center since pedestrians go through the exit with less turning.

Calculation of midplane dose for total body irradiation from entrance and exit dose MOSFET measurements.

PubMed

Satory, P R

2012-03-01

This work is the development of a MOSFET based surface in vivo dosimetry system for total body irradiation patients treated with bilateral extended SSD beams using PMMA missing tissue compensators adjacent to the patient. An empirical formula to calculate midplane dose from MOSFET measured entrance and exit doses has been derived. The dependency of surface dose on the air-gap between the spoiler and the surface was investigated by suspending a spoiler above a water phantom, and taking percentage depth dose measurements (PDD). Exit and entrances doses were measured with MOSFETs in conjunction with midplane doses measured with an ion chamber. The entrance and exit doses were combined using an exponential attenuation formula to give an estimate of midplane dose and were compared to the midplane ion chamber measurement for a range of phantom thicknesses. Having a maximum PDD at the surface simplifies the prediction of midplane dose, which is achieved by ensuring that the air gap between the compensator and the surface is less than 10 cm. The comparison of estimated midplane dose and measured midplane dose showed no dependence on phantom thickness and an average correction factor of 0.88 was found. If the missing tissue compensators are kept within 10 cm of the patient then MOSFET measurements of entrance and exit dose can predict the midplane dose for the patient.

Emissions Prediction and Measurement for Liquid-Fueled TVC Combustor with and without Water Injection

NASA Technical Reports Server (NTRS)

Brankovic, A.; Ryder, R. C., Jr.; Hendricks, R. C.; Liu, N.-S.; Shouse, D. T.; Roquemore, W. M.

2005-01-01

An investigation is performed to evaluate the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid-fueled combustor that uses water injection for control of pollutant emissions. The experiment consists of a multisector, liquid-fueled combustor rig operated at different inlet pressures and temperatures, and over a range of fuel/air and water/fuel ratios. Fuel can be injected directly into the main combustion airstream and into the cavities. Test rig performance is characterized by combustor exit quantities such as temperature and emissions measurements using rakes and overall pressure drop from upstream plenum to combustor exit. Visualization of the flame is performed using gray scale and color still photographs and high-frame-rate videos. CFD simulations are performed utilizing a methodology that includes computer-aided design (CAD) solid modeling of the geometry, parallel processing over networked computers, and graphical and quantitative post-processing. Physical models include liquid fuel droplet dynamics and evaporation, with combustion modeled using a hybrid finite-rate chemistry model developed for Jet-A fuel. CFD and experimental results are compared for cases with cavity-only fueling, while numerical studies of cavity and main fueling was also performed. Predicted and measured trends in combustor exit temperature, CO and NOx are in general agreement at the different water/fuel loading rates, although quantitative differences exist between the predictions and measurements.

Optimized cell geometry for buffer-gas-cooled molecular-beam sources

NASA Astrophysics Data System (ADS)

Singh, Vijay; Samanta, Amit K.; Roth, Nils; Gusa, Daniel; Ossenbrüggen, Tim; Rubinsky, Igor; Horke, Daniel A.; Küpper, Jochen

2018-03-01

We have designed, constructed, and commissioned a cryogenic helium buffer-gas source for producing a cryogenically cooled molecular beam and evaluated the effect of different cell geometries on the intensity of the produced molecular beam, using ammonia as a test molecule. Planar and conical entrance and exit geometries are tested. We observe a threefold enhancement in the NH3 signal for a cell with planar entrance and conical-exit geometry, compared to that for a typically used "boxlike" geometry with planar entrance and exit. These observations are rationalized by flow field simulations for the different buffer-gas cell geometries. The full thermalization of molecules with the helium buffer gas is confirmed through rotationally resolved resonance-enhanced multiphoton ionization spectra yielding a rotational temperature of 5 K.

Domain-adaptive finite difference methods for collapsing annular liquid jets

NASA Astrophysics Data System (ADS)

Ramos, J. I.

1993-01-01

A domain-adaptive technique which maps a time-dependent, curvilinear geometry into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets. A method of lines is used to solve the one-dimensional fluid dynamics equations written in weak conservation-law form, and upwind differences are employed to evaluate the axial convective fluxes. The unknown, time-dependent, axial location of the downstream boundary is determined from the solution of an ordinary differential equation which is nonlinearly coupled to the fluid dynamics and gas concentration equations. The equation for the gas concentration in the annular liquid jet is written in strong conservation-law form and solved by means of a method of lines at high Peclet numbers and a line Gauss-Seidel method at low Peclet numbers. The effects of the number of grid points along and across the annular jet, time step, and discretization of the radial convective fluxes on both the steady state mass absorption rate and the jet's collapse rate have been analyzed on staggered and non-staggered grids. The steady state mass absorption rate and the collapse of annular liquid jets are determined as a function of the Froude, Peclet and Weber numbers, annular jet's thickness-to-radius ratio at the nozzle exit, initial pressure difference across the annular jet, nozzle exit angle, temperature of the gas enclosed by the annular jet, pressure of the gas surrounding the jet, solubilities at the inner and outer interfaces of the annular jet, and gas concentration at the nozzle exit. It is shown that the steady state mass absorption rate is proportional to the inverse square root of the Peclet number except for low values of this parameter, and that the possible mathematical incompatibilities in the concentration field at the nozzle exit exert a great influence on the steady state mass absorption rate and on the jet collapse. It is also shown that the steady state mass absorption rate increases as the Weber number, nozzle exit angle, gas concentration at the nozzle exit, and temperature of the gases enclosed by the annular liquid jet are increased, but it decreases as the Froude and Peclet numbers, and annular liquid jet's thickness-to-radius ratio at the nozzle exit are increased. It is also shown that the annular liquid jet's collapse rate increases as the Weber number, nozzle exit angle, temperature of the gases enclosed by the annular liquid jet, and pressure of the gases which surround the jet are increased, but decreases as the Froude and Peclet numbers, and annular liquid jet's thickness-toradius ratio at the nozzle exit are increased. It is also shown that both the ratio of the initial pressure of the gas enclosed by the jet to the pressure of the gas surrounding the jet and the ratio of solubilities at the annular liquid jet's inner and outer interfaces play an important role on both the steady state mass absorption rate and the jet collapse. If the product of these ratios is greater or less than one, both the pressure and the mass of the gas enclosed by the annular liquid jet decrease or increase, respectively, with time. It is also shown that the numerical results obtained with the conservative, domain-adaptive method of lines technique presented in this paper are in excellent agreement with those of a domain-adaptive, iterative, non-conservative, block-bidiagonal, finite difference method which uncouples the solution of the fluid dynamics equations from that of the convergence length.

Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

2008-01-01

An investigation of distortions of the rotor exit flow field caused by an aerodynamic probe mounted in the rotor is described in this paper. A rotor total pressure Kiel probe, mounted on the rotor hub and extending up to the mid-span radius of a rotor blade channel, generates a wake that forms additional flow blockage. Three types of high-response aerodynamic probes were used to investigate the distorted flow field behind the rotor. These probes were: a split-fiber thermo-anemometric probe to measure velocity and flow direction, a total pressure probe, and a disk probe for in-flow static pressure measurement. The signals acquired from these high-response probes were reduced using an ensemble averaging method based on a once per rotor revolution signal. The rotor ensemble averages were combined to construct contour plots for each rotor channel of the rotor tested. In order to quantify the rotor probe effects, the contour plots for each individual rotor blade passage were averaged into a single value. The distribution of these average values along the rotor circumference is a measure of changes in the rotor exit flow field due to the presence of a probe in the rotor. These distributions were generated for axial flow velocity and for static pressure.

Modeling Film-Coolant Flow Characteristics at the Exit of Shower-Head Holes

NASA Technical Reports Server (NTRS)

Garg, Vijay K.; Gaugler, R. E. (Technical Monitor)

2000-01-01

The coolant flow characteristics at the hole exits of a film-cooled blade are derived from an earlier analysis where the hole pipes and coolant plenum were also discretized. The blade chosen is the VKI rotor with three staggered rows of shower-head holes. The present analysis applies these flow characteristics at the shower-head hole exits. A multi-block three-dimensional Navier-Stokes code with Wilcox's k-omega model is used to compute the heat transfer coefficient on the film-cooled turbine blade. A reasonably good comparison with the experimental data as well as with the more complete earlier analysis where the hole pipes and coolant plenum were also gridded is obtained. If the 1/7th power law is assumed for the coolant flow characteristics at the hole exits, considerable differences in the heat transfer coefficient on the blade surface, specially in the leading-edge region, are observed even though the span-averaged values of h (heat transfer coefficient based on T(sub o)-T(sub w)) match well with the experimental data. This calls for span-resolved experimental data near film-cooling holes on a blade for better validation of the code.

[Study on spray-drier preparation technology of weitai granules using orthogonal experiments].

PubMed

Qu, Cai-Hong; Yang, Li; Chen, Zhi-Liang

2006-04-01

To screen preparation technique in order to raise the end-product and economical efficiency of spray-drier preparation technology of weitai granules. Newly Fluid-bed-spray-drier-granulation technique was adoped and taken extracting technique, temperature of exit and entry and the matching of accessories as inspecting factors, two levels of each factors, end-product and the water content of semi-finished weitai granules as inspecting marker, the best preparation technique of weitai granules was screened by orthogonal desing. Among the 3 factors, the matching of accessories was most notalbe (P < 0.01), next was the temperature of exit and entry (P < 0.05). However, the extracting technique was of little importance (P > 0.05). The optimum spray-drier granulation technique of weitai granules is A3B1C3.

Simplified analysis and optimization of space base and space shuttle heat rejection systems

NASA Technical Reports Server (NTRS)

Wulff, W.

1972-01-01

A simplified radiator system analysis was performed to predict steady state radiator system performance. The system performance was found to be describable in terms of five non-dimensional system parameters. The governing differential equations are integrated numerically to yield the enthalpy rejection for the coolant fluid. The simplified analysis was extended to produce the derivatives of the coolant exit temperature with respect to the governing system parameters. A procedure was developed to find the optimum set of system parameters which yields the lowest possible coolant exit temperature for either a given projected area or a given total mass. The process can be inverted to yield either the minimum area or the minimum mass, together with the optimum geometry, for a specified heat rejection rate.

Wrong-way vehicle detection : proof of concept.

DOT National Transportation Integrated Search

2013-03-01

Vehicles that enter freeway exit ramps going the wrong way present one of the most serious traffic hazards on : Arizonas urban freeways. Moler cites a study that finds on average 350 people are killed annually in the United : States as a result of...

40 CFR 503.40 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS FOR THE USE OR... sewage sludge incinerator stack is monitored continuously for carbon monoxide. (2) The monthly average concentration of carbon monoxide in the exit gas from a sewage sludge incinerator stack, corrected for zero...

General practitioner turnover and migration in England 1990-94.

PubMed Central

Taylor, D H; Leese, B

1998-01-01

BACKGROUND: In tandem with fears about a GP workforce crisis, increasing attention is being focused on the supply and distribution of primary care services: on general practitioners in particular. Differential turnover and migration across health authority boundaries could lead to a maldistribution of GPs, yet comprehensive studies of GP turnover are non-existent. AIM: To quantify general practitioner (GP) turnover and migration in England from 1990 to 1994. METHOD: Yearly data from 1 October 1990 to 1 October 1994 were collected on GPs in England practising full time, including average yearly turnover, rates of entry to and exit from general practice, and net migration among GPs. All were calculated at the family health service authority (now the new health authorities) level. RESULTS: Average yearly GP turnover ranges from 2.9% in Shropshire to 7.8% in Kensington, Chelsea and Westminster; turnover is associated with deprivation and high-need areas. Migration of GPs across health authority borders was rare. Entry and exit rates were also positively related to measures of deprivation and need. Relatively underprovided health authorities lost 23 GPs over the study period as a result of migration; relatively overprovided ones gained three. CONCLUSION: Turnover is driven primarily by exits from general practice and is related to deprivation and high need. Retention appears to be the main problem in ensuring an adequate GP supply in relatively deprived and underprovided health authorities. PMID:9624750

Training and technology statistical report, October 1979-September 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-01-01

A total of 839 trainees were enrolled at TAT during the 1979 to 1980 training year. Section One of this statistical report includes information on only those 613 trainees who exited training between October 1, 1979, and September 30, 1980. Demographic, educational, and employment data on the 613 exiting trainees - graduates and nongraduates - are summarized. There were 478 graduates (78% of concluding trainees), of whom 459 were available for placement. Profile summaries of graduates and nongraduates are tabulated. Of the 459 available for placement, 432 were placed in jobs with beginning wages averaging $6.34 per hour. The estimatedmore » annual income for those who were placed, assuming 2080 h/y, was $13,187. The majority of graduates, 85.8%, were unemployed at the time they entered TAT. The remainder, 14.2% of graduates, reported wages averaging $3.62 per hour at entry to training. Projected on an annual basis, those graduates employed at entry earned $7529. Compared to the average starting wage of placed TAT trainees on their first jobs after graduation, $13,187, their increased earnings were $5658 or a 75% increase after training. During the training year there were 135 trainees who did not graduate. Exit information on these nongraduates is presented. In addition to industrial skills training, TAT offers trainees who do not have a high school diploma or its equivalent the opportunity to work on the General Education Development (GED) by studying at TAT. Thirty-five trainees received their GED certification during the 1979 to 1980 training year. Supplementary statistical data on TAT enrollments, training and placement from 1966 to 1980 is provided.« less

Laser Transmission Measurements of Soot Extinction Coefficients in the Exhaust Plume of the X-34 60K-lb Thrust Fastrac Rocket Engine

NASA Technical Reports Server (NTRS)

Dobson, C. C.; Eskridge, R. H.; Lee, M. H.

2000-01-01

A four-channel laser transmissometer has been used to probe the soot content of the exhaust plume of the X-34 60k-lb thrust Fastrac rocket engine at NASA's Marshall Space Flight Center. The transmission measurements were made at an axial location approximately equal 1.65 nozzle diameters from the exit plane and are interpreted in terms of homogeneous radial zones to yield extinction coefficients from 0.5-8.4 per meter. The corresponding soot mass density, spatially averaged over the plume cross section, is, for Rayleigh particles, approximately equal 0.7 microgram/cc, and alternative particle distributions are briefly considered. Absolute plume radiance at the laser wavelength (515 nm) is estimated from the data at approximately equal 2,200 K equivalent blackbody temperature, and temporal correlations in emission from several spatial locations are noted.

Laser Transmission Measurements of Soot Extinction Coefficients in the Exhaust Plume of the X-34 60k-lb Thrust Fastrac Rocket Engine

NASA Technical Reports Server (NTRS)

Dobson, C. C.; Eskridge, R. H.; Lee, M. H.

2000-01-01

A four-channel laser transmissometer has been used to probe the soot content of the exhaust plume of the X-34 60k-lb thrust Fastrac rocket engine at NASA's Marshall Space Flight Center. The transmission measurements were made at an axial location about equal 1.65 nozzle diameters from the exit plane and are interpreted in terms of homogeneous radial zones to yield extinction coefficients from 0.5-8.4 per meter. The corresponding soot mass density, spatially averaged over the plume cross section, is, for Rayleigh particles, approximately equal to 0.7 micrograms/cubic cm and alternative particle distributions are briefly considered. Absolute plume radiance at the laser wavelength (515 nm) is estimated from the data at approximately equal to 2.200 K equivalent blackbody temperature, and temporal correlations in emission from several spatial locations are noted.

Construction of an easy-to-use CRISPR-Cas9 system by patching a newly designed EXIT circuit.

PubMed

Tang, Qiang; Lou, Chunbo; Liu, Shuang-Jiang

2017-01-01

Plasmid-borne genetic editing tools, including the widely used CRISPR-Cas9 system, have greatly facilitated bacterial programming to obtain novel functionalities. However, the lack of effective post-editing plasmid elimination methods impedes follow-up genetic manipulation or application. Conventional strategies including exposure to physical and chemical treatments, or exploiting temperature-sensitive replication origins have several drawbacks (e.g., they are limited for efficiency and are time-consuming). Therefore, the demand is apparent for easy and rapid elimination of the tool plasmids from their bacterial hosts after genetic manipulation. To bridge this gap, we designed a novel EXIT circuit with the homing endonuclease, which can be exploited for rapid and efficient elimination of various plasmids with diverse replication origins. As a proof of concept, we validated the EXIT circuit in Escherichia coli by harnessing homing endonuclease I- Sce I and its cleavage site. When integrated into multiple plasmids with different origins, the EXIT circuit allowed them to be eliminated from the host cells, simultaneously. By combining the widely used plasmid-borne CRISPR-Cas9 system and the EXIT circuit, we constructed an easy-to-use CRISPR-Cas9 system that eliminated the Cas9- and the single-guide RNA (sgRNA)-encoding plasmids in one-step. Within 3 days, we successfully constructed an atrazine-degrading E. coli strain, thus further demonstrating the advantage of this new CRISPR-Cas9 system for bacterial genome editing. Our novel EXIT circuit, which exploits the homing endonuclease I- Sce I, enables plasmid(s) with different replication origins to be eliminated from their host cells rapidly and efficiently. We also developed an easy-to-use CRISPR-Cas9 system with the EXIT circuit, and this new system can be widely applied to bacterial genome editing.

Parametric study of a concentric coaxial glass tube solar air collector: a theoretical approach

NASA Astrophysics Data System (ADS)

Dabra, Vishal; Yadav, Avadhesh

2018-06-01

Concentric coaxial glass tube solar air collector (CCGTSAC) is a quite innovative development in the field of solar collectors. This type of collector is specially designed to produce hot air. A mathematical model based on the energy conservation equations for small control volumes along the axial direction of concentric coaxial glass tube (CCGT) is developed in this paper. It is applied to predict the effect of thirteen different parameters on the exit air temperature rise and appeared that absorber tube size, length of CCGT, absorptivity of transparent glazing, transmissivity of transparent glazing, absorptivity of absorber coating, inlet or ambient air temperature, mass flow rate, variation of thermo-physical properties of air, wind speed, solar intensity and vacuum present between transparent glazing and absorber tube are significant parameters. Results of the model were analysed to predict the effect of key parameters on the thermal performance of a CCGTSAC for exit air temperature rise about 43.9-58.4 °C.

Parametric study of a concentric coaxial glass tube solar air collector: a theoretical approach

NASA Astrophysics Data System (ADS)

Dabra, Vishal; Yadav, Avadhesh

2017-12-01

Concentric coaxial glass tube solar air collector (CCGTSAC) is a quite innovative development in the field of solar collectors. This type of collector is specially designed to produce hot air. A mathematical model based on the energy conservation equations for small control volumes along the axial direction of concentric coaxial glass tube (CCGT) is developed in this paper. It is applied to predict the effect of thirteen different parameters on the exit air temperature rise and appeared that absorber tube size, length of CCGT, absorptivity of transparent glazing, transmissivity of transparent glazing, absorptivity of absorber coating, inlet or ambient air temperature, mass flow rate, variation of thermo-physical properties of air, wind speed, solar intensity and vacuum present between transparent glazing and absorber tube are significant parameters. Results of the model were analysed to predict the effect of key parameters on the thermal performance of a CCGTSAC for exit air temperature rise about 43.9-58.4 °C.

Emission spectroscopy and laser-induced fluorescence measurements on the plume from a 1-kW arcjet operated on simulated ammonia

NASA Technical Reports Server (NTRS)

Ruyten, Wilhelmus M.; Burtner, D.; Keefer, Dennis

1993-01-01

Spectroscopic and laser-induced fluorescence measurements were performed on the exhaust plume from a 1 kW NASA Lewis arcjet, operated on simulated ammonia. In particular, emissions were analyzed from the Balmer lines of atomic hydrogen and from one of the rotational bands of the NH radical. The laser-induced fluorescence measurements were performed on the Balmer-alpha line of atomic hydrogen. We find that exit plane temperatures are in the range 1500 to 3500 K and that the electron density upstream of the exit plane is on the order of 1.5 x 10(exp 14)/cu cm as determined by the Stark width of the Balmer-alpha line. Both emission spectroscopy and laser-induced fluorescence were used to measure the plume velocities of atomic hydrogen. Using either technique, velocities on the order of 4 km/sec were found at the exit plane and significant acceleration of the flow was observed in the first 2 mm beyond the exit plane. This result indicates that the design of the arcjet nozzle may not be optimum.

Investigation of the feasibility of optical diagnostic measurements at the exit of the SSME

NASA Technical Reports Server (NTRS)

Shirley, John A.; Boedeker, Laurence R.

1993-01-01

Under Contract NAS8-36861 sponsored by NASA Marshall Space Flight Center, the United Technologies Research Center is conducting an investigation of the feasibility of remote optical diagnostics to measure temperature, species concentration and velocity at the exit of the Space Shuttle Main Engine (SSME). This is a two phase study consisting of a conceptual design phase followed by a laboratory experimental investigation. The first task of the conceptual design studies is to screen and evaluate the techniques which can be used for the measurements. The second task is to select the most promising technique or techniques, if as expected, more than one type of measurement must be used to measure all the flow variables of interest. The third task is to examine in detail analytically the capabilities and limitations of the selected technique(s). The results of this study are described in the section of this report entitled Conceptual Design Investigations. The conceptual design studies identified spontaneous Raman scattering and photodissociative flow-tagging for measurements respectively of gas temperature and major species concentration and for velocity. These techniques and others that were considered are described in the section describing the conceptual design. The objective of the second phase of investigations was to investigate experimentally the techniques identified in the first phase. The first task of the experimental feasibility study is to design and assemble laboratory scale experimental apparatus to evaluate the best approaches for SSME exit optical diagnostics for temperature, species concentrations and velocity, as selected in the Phase I conceptual design study. The second task is to evaluate performance, investigate limitations, and establish actual diagnostic capabilities, accuracies and precision for the selected optical systems. The third task is to evaluate design requirements and system trade-offs of conceptual instruments. Spontaneous Raman scattering excited by a KrF excimer laser pulse was investigated for SSME exit plane temperature and major species concentration measurements. The relative concentrations of molecular hydrogen and water vapor would be determined by measuring the integrated Q-branch scattering signals through narrow bandpass filters in front of photomultipliers. The temperature would be determined by comparing the signal from a single hydrogen rotational Raman line to the total hydrogen Q-branch signal. The rotational Raman line would be isolated by a monochromator and detected with a PMT.

Fundamental Studies of the Electrode Regions in Arcjet Thrusters

DTIC Science & Technology

1998-03-01

Hall thruster . This contributed to a comprehensive study of the near exit region of our Hall discharge device. To compliment the LIF diagnostics on our Hall thrusters, we have made extensive measurements of the transient and time average plasma properties using conventional electrostatic

Factors associated with biosafety level-2 research workers' laboratory exit handwashing behaviors and glove removal compliance.

PubMed

Johnston, James D; Merrill, Ray M; Zimmerman, Grant C; Collingwood, Scott C; Reading, James C

2016-01-01

Biosafety level-2 laboratories are designated for work with human-derived samples or moderate-risk microorganisms that transmit primarily by direct contact exposures. Many laboratory procedures generate unseen droplets that contaminate workers' hands, equipment, and work surfaces. Workers' strict adherence to glove removal and handwashing is required prior to laboratory exit to prevent inadvertent transmission of pathogens to self or others. However, little is known about biosafety level-2 workers' compliance with these behaviors. In this article, glove removal and handwashing compliance upon laboratory exit were measured by direct observation of 93 biosafety level-2 research workers from 21 university laboratories. Participants completed a 41-item survey measuring social cognitive theory-based variables related to handwashing, self-reported compliance, and demographic factors. Survey items, observed exit frequency, and laboratory characteristics were evaluated for associations with handwashing compliance. Overall, observed glove removal and handwashing compliance upon laboratory exit were 43.0% (Standard Error [SE] = 2.3%), and 8.2% (SE = 1.2%), respectively, while workers' self-reported glove removal and handwashing compliance were 73.7% (SE = 3.6%) and 35.5% (SE = 4.1%), respectively. The average number of observed laboratory exits per hour was 2.8 for workers with any handwashing compliance vs. 5.4 for workers with no handwashing compliance (p = 0.0013). Among the cognitive variables, behavioral modeling by supervisors and coworkers had the strongest association with workers' compliance (slope = 3.5, SE = 1.3, p = 0.0113). Workers in laboratories with a written handwashing policy had higher compliance (Mean = 14.1%, SE = 5.9%) than workers in laboratories with no written policy (Mean = 1.1%, SE = 1.0%; p = 0.0488). Multi-faceted interventions that encourage modeling of the behavior by supervisors and coworkers, implementation of written handwashing policies, and efforts to reduce exit frequency by furnishing laboratories with necessary equipment and supplies may help improve compliance.

Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

NASA Technical Reports Server (NTRS)

Russin, W. R.

1974-01-01

Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

Characterization of the NASA Langley Arc Heated Scramjet Test Facility Using NO PLIF

NASA Technical Reports Server (NTRS)

Kidd, F. Gray, III; Narayanaswamy, Venkateswaran; Danehy, Paul M.; Inman, Jennifer A.; Bathel, Brett F.; Cabell, Karen F.; Hass, Neal E.; Capriotti, Diego P.; Drozda, Tomasz G.; Johansen, Criag T.

2014-01-01

The nitric oxide planar laser-induced fluorescence (NO PLIF) imaging was used to characterize the air flow of the NASA Langley Arc Heated Scramjet Test Facility (AHSTF) configured with a Mach 6 nozzle. The arc raises the enthalpy of the test gas in AHSTF, producing nitric oxide. Nitric oxide persists as the temperature drops through the nozzle into the test section. NO PLIF was used to qualitatively visualize the flowfield at different experimental conditions, measure the temperature of the gas flow exiting the facility nozzle, and visualize the wave structure downstream of the nozzle at different operating conditions. Uniformity and repeatability of the nozzle flow were assessed. Expansion and compression waves on the free-jet shear layer as the nozzle flow expands into the test section were visualized. The main purpose of these experiments was to assess the uniformity of the NO in the freestream gas for planned experiments, in which NO PLIF will be used for qualitative fuel-mole-fraction sensitive imaging. The shot-to-shot fluctuations in the PLIF signal, caused by variations in the overall laser intensity as well as NO concentration and temperature variations in the flow was 20-25% of the mean signal, as determined by taking the standard deviation of a set of images obtained at constant conditions and dividing by the mean. The fluctuations within individual images, caused by laser sheet spatial variations as well as NO concentration and temperature variations in the flow, were about 28% of the mean in images, determined by taking standard deviation within individual images, dividing by the mean in the same image and averaged over the set of images. Applying an averaged laser sheet intensity correction reduced the within-image intensity fluctuations to about 10% suggesting that the NO concentration is uniform to within 10%. There was no significant difference in flow uniformity between the low and high enthalpy settings. While not strictly quantitative, the temperature maps show qualitative agreement with the computations of the flow.

40 CFR 63.2997 - What are the requirements for monitoring devices?

Code of Federal Regulations, 2011 CFR

2011-07-01

... continuously the thermal oxidizer temperature at the exit of the combustion zone before any substantial heat exchange occurs or at the location consistent with the manufacturer's recommendations. (2) Continuously...

40 CFR 63.2997 - What are the requirements for monitoring devices?

Code of Federal Regulations, 2010 CFR

2010-07-01

... continuously the thermal oxidizer temperature at the exit of the combustion zone before any substantial heat exchange occurs or at the location consistent with the manufacturer's recommendations. (2) Continuously...

Material Science of Carbon

DTIC Science & Technology

2004-09-01

required for a specific application. The list of applications is very extensive and includes: aircraft brakes, electrodes, high temperature molds, rocket...and includes: aircraft brakes, electrodes, high temperature molds, rocket nozzles and exit cones, tires, ink, nuclear reactors and fuel particles...produced. For example carbons can be hard (chars) or soft (blacks), strong (PAN fibers) or weak ( aerogel ), stiff (pitch fibers) or flexible

Impact of an Individual Mandate and Other Health Reforms on Dependent Coverage for Adolescents and Young Adults.

PubMed

Wisk, Lauren E; Finkelstein, Jonathan A; Toomey, Sara L; Sawicki, Gregory S; Schuster, Mark A; Galbraith, Alison A

2018-06-01

To determine the effect of state-level dependent coverage expansion (DCE) with and without other state health reforms on exit from dependent coverage for adolescents and young adults (AYA). Administrative longitudinal data for 131,542 privately insured AYA in Massachusetts (DCE with other reforms) versus Maine and New Hampshire (DCE without other reforms) across three periods: prereform (1/00-12/06), poststate reform (1/07-9/10), and postfederal reform (10/10-12/12). A difference-in-differences estimator was used to determine the rate of exit from dependent coverage, age at exit from dependent coverage, and re-uptake of dependent coverage among AYA in states with comprehensive reforms versus DCE only. Implementation of DCE with other reforms was significantly associated with a 23 percent reduction in exit from dependent coverage among AYA compared to the reduction observed for DCE alone. Additionally, comprehensive reforms were associated with over two additional years of dependent coverage for the average AYA and a 33 percent increase in the odds of regaining dependent coverage after a prior loss. Findings suggest that an individual mandate and other reforms may enhance the effect of DCE in preventing loss of coverage among AYA. © Health Research and Educational Trust.

Interkinetic and migratory behavior of a cohort of neocortical neurons arising in the early embryonic murine cerebral wall

NASA Technical Reports Server (NTRS)

Takahashi, T.; Nowakowski, R. S.; Caviness, V. S. Jr

1996-01-01

Neocortical neuronogenesis occurs in the pseudostratified ventricular epithelium (PVE) where nuclei of proliferative cells undergo interkinetic nuclear movement. A fraction of daughter cells exits the cell cycle as neurons (the quiescent, or Q, fraction), whereas a complementary fraction remains in the cell cycle (the proliferative, or P, fraction). By means of sequential thymidine and bromodeoxyuridine injections in mouse on embryonic day 14, we have monitored the proliferative and post-mitotic migratory behaviors of 1 and 2 hr cohorts of PVE cells defined by the injection protocols. Soon after mitosis, the Q fraction partitions into a rapidly exiting (up to 50 microns/hr) subpopulation (Qr) and a more slowly exiting (6 microns/hr) subpopulation (Qs). Qr and Qs are separated as two distributions on exit from the ventricular zone with an interpeak distance of approximately 40 microns. Cells in Qr and Qs migrate through the intermediate zone with no significant change in the interpeak distance, suggesting that they migrate at approximately the same velocities. The rate of migration increases with ascent through the intermediate zone (average 2-6.4 microns/hr) slowing only transiently on entry into the developing cortex. Within the cortex, Qr and Qs merge to form a single distribution most concentrated over layer V.

Conical diffuser for fuel cells

NASA Technical Reports Server (NTRS)

Craft, D. W.

1976-01-01

Diffuser is inserted into inlet manifold, producing smooth transition of flow from pipe diameter to manifold diameter. Expected pressure gradient and resulting cell-to-cell temperature gradient are reduced. Outlet manifold has nozzle insert that reduces exit losses.

Possibilities of creating a pure coal-fired power industry based on nanomaterials

NASA Astrophysics Data System (ADS)

Zyryanov, V. V.

2015-08-01

A concept of distributed multigeneration during combustion of homogenized solid fuels with the addition of oxygen-enriched (to 30-50%) air is proposed. To implement this concept, application of medium-temperature δ-Bi2O3/Ag-nanocermet-based membranes is suggested under low pressures and sweeping of oxygen by the cleaned exit gas or the air. The primary product of the multigeneration is microsphere materials. The heat, the AC and the DC electric energy, the cleaned exit gases with a high CO2 content, and volatile elements adsorbed by the filters are the secondary products. To completely clean the exit gases, which is necessary to implement the distributed multigeneration, an array of successive passive plants is proposed. A thermoelectric module based on a BiTeSb-skutterudite nanocomposite is effective in generation of the DC electric energy at microthermoelectric power plants.

Nonlinear Modeling and Control of a Propellant Mixer

NASA Technical Reports Server (NTRS)

Barbieri, Enrique; Richter, Hanz; Figueroa, Fernando

2003-01-01

A mixing chamber used in rocket engine combustion testing at NASA Stennis Space Center is modeled by a second order nonlinear MIMO system. The mixer is used to condition the thermodynamic properties of cryogenic liquid propellant by controlled injection of the same substance in the gaseous phase. The three inputs of the mixer are the positions of the valves regulating the liquid and gas flows at the inlets, and the position of the exit valve regulating the flow of conditioned propellant. The outputs to be tracked and/or regulated are mixer internal pressure, exit mass flow, and exit temperature. The outputs must conform to test specifications dictated by the type of rocket engine or component being tested downstream of the mixer. Feedback linearization is used to achieve tracking and regulation of the outputs. It is shown that the system is minimum-phase provided certain conditions on the parameters are satisfied. The conditions are shown to have physical interpretation.

1998 Calibration of the Mach 4.7 and Mach 6 Arc-Heated Scramjet Test Facility Nozzles

NASA Technical Reports Server (NTRS)

Witte, David W.; Irby, Richard G.; Auslender, Aaron H.; Rock, Kenneth E.

2004-01-01

A calibration of the Arc-Heated Scramjet Test Facility (AHSTF) Mach 4.7 and Mach 6 nozzles was performed in 1998. For each nozzle, three different typical facility operating test points were selected for calibration. Each survey consisted of measurements, at 340 separate locations across the 11 inch square nozzle exit plane, of pitot pressure, static pressure, and total temperature. Measurement density was higher (4/inch) in the boundary layer near the nozzle wall than in the core nozzle flow (1/inch). The results generated for each of these calibration surveys were contour plots at the nozzle exit plane of the measured and calculated flow properties which completely defined the thermodynamic state of the nozzle exit flow. An area integration of the mass flux at the nozzle exit for each survey was compared to the AHSTF mass flow meter results to provide an indication of the overall quality of the calibration performed. The percent difference between the integrated nozzle exit mass flow and the flow meter ranged from 0.0 to 1.3 percent for the six surveys. Finally, a comparison of this 1998 calibration was made with the 1986 calibration. Differences of less than 10 percent were found within the nozzle core flow while in the boundary layer differences on the order of 20 percent were quite common.

40 CFR 63.9631 - What are my monitoring requirements?

Code of Federal Regulations, 2014 CFR

2014-07-01

... inspections, vibration detectors, or equivalent means. (b) Except as provided in paragraph (c) of this section... average opacity of emissions exiting each control device stack according to the requirements in § 63.9633... pollution control device other than a baghouse, wet scrubber, dry electrostatic precipitator, or wet...

40 CFR 63.9631 - What are my monitoring requirements?

Code of Federal Regulations, 2012 CFR

2012-07-01

... inspections, vibration detectors, or equivalent means. (b) Except as provided in paragraph (c) of this section... average opacity of emissions exiting each control device stack according to the requirements in § 63.9633... pollution control device other than a baghouse, wet scrubber, dry electrostatic precipitator, or wet...

40 CFR 63.9631 - What are my monitoring requirements?

Code of Federal Regulations, 2013 CFR

2013-07-01

... inspections, vibration detectors, or equivalent means. (b) Except as provided in paragraph (c) of this section... average opacity of emissions exiting each control device stack according to the requirements in § 63.9633... pollution control device other than a baghouse, wet scrubber, dry electrostatic precipitator, or wet...

Transient liquid-crystal technique used to produce high-resolution convective heat-transfer-coefficient maps

NASA Technical Reports Server (NTRS)

Hippensteele, Steven A.; Poinsatte, Philip E.

1993-01-01

In this transient technique the preheated isothermal model wall simulates the classic one-dimensional, semi-infinite wall heat transfer conduction problem. By knowing the temperature of the air flowing through the model, the initial temperature of the model wall, and the surface cooling rate measured at any location with time (using the fast-response liquid-crystal patterns recorded on video tape), the heat transfer coefficient can be calculated for the color isothermal pattern produced. Although the test was run transiently, the heat transfer coefficients are for the steady-state case. The upstream thermal boundary condition was considered to be isothermal. This transient liquid-crystal heat-transfer technique was used in a transient air tunnel in which a square-inlet, 3-to-1 exit transition duct was placed. The duct was preheated prior to allowing room temperature air to be suddenly drawn through it. The resulting isothermal contours on the duct surfaces were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the temperature and time data for all points on the duct surfaces during each test. The duct surfaces were uniformly heated using two heating systems: the first was an automatic temperature-controlled heater blanket completely surrounding the test duct like an oven, and the second was an internal hot-air loop through the inside of the test duct. The hot-air loop path was confined inside the test duct by insulated heat dams located at the inlet and exit ends of the test duct. A recirculating fan moved hot air into the duct inlet, through the duct, out of the duct exit, through the oven, and back to the duct inlet. The temperature nonuniformity of the test duct model wall was held very small. Test results are reported for two inlet Reynolds numbers of 200,000 and 1,150,000 (based on the square-inlet hydraulic diameter) and two free-stream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 20 percent (using a grid), which is typical of real engine conditions.

A novel functional domain of Cdc15 kinase is required for its interaction with Tem1 GTPase in Saccharomyces cerevisiae.

PubMed Central

Asakawa, K; Yoshida, S; Otake, F; Toh-e, A

2001-01-01

Exit from mitosis requires the inactivation of cyclin-dependent kinase (CDK) activity. In the budding yeast Saccharomyces cerevisiae, a number of gene products have been identified as components of the signal transduction network regulating inactivation of CDK (called the MEN, for the mitotic exit network). Cdc15, one of such components of the MEN, is an essential protein kinase. By the two-hybrid screening, we identified Cdc15 as a binding protein of Tem1 GTPase, another essential regulator of the MEN. Coprecipitation experiments revealed that Tem1 binds to Cdc15 in vivo. By deletion analysis, we found that the Tem1-binding domain resides near the conserved kinase domain of Cdc15. The cdc15-LF mutation, which was introduced into the Tem1-binding domain, reduced the interaction with Cdc15 and Tem1 and caused temperature-sensitive growth.The kinase activity of Cdc15 was not so much affected by the cdc15-LF mutation. However, Cdc15-LF failed to localize to the SPB at the restrictive temperature. Our data show that the interaction with Tem1 is important for the function of Cdc15 and that Cdc15 and Tem1 function in a complex to direct the exit from mitosis. PMID:11290702

Supersonic/Hypersonic Correlations for In-Cavity Transition and Heating Augmentation

NASA Technical Reports Server (NTRS)

Everhart, Joel L.

2011-01-01

Laminar-entry cavity heating data with a non-laminar boundary layer exit flow have been retrieved from the database developed at Mach 6 and 10 in air on large flat plate models for the Space Shuttle Return-To-Flight Program. Building on previously published fully laminar and fully turbulent analysis methods, new descriptive correlations of the in-cavity floor-averaged heating and endwall maximum heating have been developed for transitional-to-turbulent exit flow. These new local-cavity correlations provide the expected flow and geometry conditions for transition onset; they provide the incremental heating augmentation induced by transitional flow; and, they provide the transitional-to-turbulent exit cavity length. Furthermore, they provide an upper application limit for the previously developed fully-laminar heating correlations. An example is provided that demonstrates simplicity of application. Heating augmentation factors of 12 and 3 above the fully laminar values are shown to exist on the cavity floor and endwall, respectively, if the flow exits in fully tripped-to-turbulent boundary layer state. Cavity floor heating data in geometries installed on the windward surface of 0.075-scale Shuttle wind tunnel models have also been retrieved from the boundary layer transition database developed for the Return-To-Flight Program. These data were independently acquired at Mach 6 and Mach 10 in air, and at Mach 6 in CF4. The correlation parameters for the floor-averaged heating have been developed and they offer an exceptionally positive comparison to previously developed laminar-cavity heating correlations. Non-laminar increments have been extracted from the Shuttle data and they fall on the newly developed transitional in-cavity correlations, and they are bounded by the 95% correlation prediction limits. Because the ratio of specific heats changes along the re-entry trajectory, turning angle into a cavity and boundary layer flow properties may be affected, raising concerns regarding the application validity of the heating augmentation predictions.

On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet

NASA Astrophysics Data System (ADS)

Prevosto, L.; Kelly, H.; Mancinelli, B. R.

2014-05-01

Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10 900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 1022 m-3 were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prevosto, L.; Mancinelli, B. R.; Kelly, H.

Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processesmore » inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.« less

On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet.

PubMed

Prevosto, L; Kelly, H; Mancinelli, B R

2014-05-01

Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10,900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 10(22) m(-3) were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

Apparatus, components and operating methods for circulating fluidized bed transport gasifiers and reactors

DOEpatents

Vimalchand, Pannalal; Liu, Guohai; Peng, Wan Wang

2015-02-24

The improvements proposed in this invention provide a reliable apparatus and method to gasify low rank coals in a class of pressurized circulating fluidized bed reactors termed "transport gasifier." The embodiments overcome a number of operability and reliability problems with existing gasifiers. The systems and methods address issues related to distribution of gasification agent without the use of internals, management of heat release to avoid any agglomeration and clinker formation, specific design of bends to withstand the highly erosive environment due to high solid particles circulation rates, design of a standpipe cyclone to withstand high temperature gasification environment, compact design of seal-leg that can handle high mass solids flux, design of nozzles that eliminate plugging, uniform aeration of large diameter Standpipe, oxidant injection at the cyclone exits to effectively modulate gasifier exit temperature and reduction in overall height of the gasifier with a modified non-mechanical valve.

High efficiency Brayton cycles using LNG

DOEpatents

Morrow, Charles W [Albuquerque, NM

2006-04-18

A modified, closed-loop Brayton cycle power conversion system that uses liquefied natural gas as the cold heat sink media. When combined with a helium gas cooled nuclear reactor, achievable efficiency can approach 68 76% (as compared to 35% for conventional steam cycle power cooled by air or water). A superheater heat exchanger can be used to exchange heat from a side-stream of hot helium gas split-off from the primary helium coolant loop to post-heat vaporized natural gas exiting from low and high-pressure coolers. The superheater raises the exit temperature of the natural gas to close to room temperature, which makes the gas more attractive to sell on the open market. An additional benefit is significantly reduced costs of a LNG revaporization plant, since the nuclear reactor provides the heat for vaporization instead of burning a portion of the LNG to provide the heat.

Temporally resolved ozone distribution of a time modulated RF atmospheric pressure argon plasma jet: flow, chemical reaction, and transient vortex

NASA Astrophysics Data System (ADS)

Zhang, S.; Sobota, A.; van Veldhuizen, E. M.; Bruggeman, P. J.

2015-08-01

The ozone density distribution in the effluent of a time modulated RF atmospheric pressure plasma jet (APPJ) is investigated by time and spatially resolved by UV absorption spectroscopy. The plasma jet is operated with an averaged dissipated power of 6.5 W and gas flow rate 2 slm argon  +2% O2. The modulation frequency of the RF power is 50 Hz with a duty cycle of 50%. To investigate the production and destruction mechanism of ozone in the plasma effluent, the atomic oxygen and gas temperature is also obtained by TALIF and Rayleigh scattering, respectively. A temporal increase in ozone density is observed close to the quartz tube exit when the plasma is switched off due to the decrease in O density and gas temperature. Ozone absorption at different axial positions indicates that the ozone distribution is dominated by the convection induced by the gas flow and allows estimating the on-axis local gas velocity in the jet effluent. Transient vortex structures occurring during the switch on and off of the RF power also significantly affect the ozone density in the far effluent.

Variability in Small Hive Beetle (Coleoptera: Nitidulidae) Reproduction in Laboratory and Field Experiments.

PubMed

Meikle, William G; Holst, Niels; Cook, Steven C; Patt, Joseph M

2015-06-01

Experiments were conducted to examine how several key factors affect population growth of the small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae). Laboratory experiments were conducted to examine effects of food quantity and temperature on reproduction of cohorts of young A. tumida adults (1:1 sex ratio) housed in experimental arenas. Daily numbers and total mass of larvae exiting arenas were highly variable within treatment. Either one or two cohorts of larvae were observed exiting the arenas. Food quantity, either 10 g or 20 g, did not significantly affect the number of larvae exiting arenas at 32°C, but did at 28°C; arenas provided 20 g food produced significantly more larvae than arenas provided 10 g. Temperature did not affect the total mass of larvae provided 10 g food, but did affect larval mass provided 20 g; beetles kept at 28°C produced more larval mass than at 32°C. Field experiments were conducted to examine A. tumida reproductive success in full strength bee colonies. Beetles were introduced into hives as egg-infested frames and as adults, and some bee colonies were artificially weakened through removal of sealed brood. Efforts were unsuccessful; no larvae were observed exiting from, or during the inspection of, any hives. Possible reasons for these results are discussed. The variability observed in A. tumida reproduction even in controlled laboratory conditions and the difficulty in causing beetle infestations in field experiments involving full colonies suggest that accurately forecasting the A. tumida severity in such colonies will be difficult. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

49 CFR 228.309 - Structure, emergency egress, lighting, temperature, and noise-level standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... occupants are present, the pathway to any exit not immediately accessible to occupants, such as through an... floor, provided that where the pathway passes through a sleeping compartment, the pathway up to the...

49 CFR 228.309 - Structure, emergency egress, lighting, temperature, and noise-level standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... occupants are present, the pathway to any exit not immediately accessible to occupants, such as through an... floor, provided that where the pathway passes through a sleeping compartment, the pathway up to the...

49 CFR 228.309 - Structure, emergency egress, lighting, temperature, and noise-level standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... occupants are present, the pathway to any exit not immediately accessible to occupants, such as through an... floor, provided that where the pathway passes through a sleeping compartment, the pathway up to the...

Random perturbations of a periodically driven nonlinear oscillator: escape from a resonance zone

NASA Astrophysics Data System (ADS)

Lingala, Nishanth; Sri Namachchivaya, N.; Pavlyukevich, Ilya

2017-04-01

For nonlinear oscillators, frequency of oscillations depends on the oscillation amplitude. When a nonlinear oscillator is periodically driven, the phase space consists of many resonance zones where the oscillator frequency and the driving frequency are commensurable. It is well known that, a small subset of initial conditions can lead to capture in one of the resonance zones. In this paper we study the effect of weak noise on the escape from a resonance zone. Using averaging techniques we obtain the mean exit time from a resonance zone and study the dependence of the exit rate on the parameters of the oscillator. Paper dedicated to Professor Peter W Sauer of University of Illinois on the occasion of his 70th birthday.

40 CFR 63.117 - Process vent provisions-reporting and recordkeeping requirements for group and TRE determinations...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.117 Process vent provisions—reporting... incinerators, boilers or process heaters specified in table 3 of this subpart, and averaged over the same time... content determinations, flow rate measurements, and exit velocity determinations made during the...

40 CFR 63.117 - Process vent provisions-reporting and recordkeeping requirements for group and TRE determinations...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.117 Process vent provisions—reporting... incinerators, boilers or process heaters specified in table 3 of this subpart, and averaged over the same time... content determinations, flow rate measurements, and exit velocity determinations made during the...

29 CFR 1910.1003 - 13 Carcinogens (4-Nitrobiphenyl, etc.).

Code of Federal Regulations, 2011 CFR

2011-07-01

... the top and bottom, designed and maintained so as to draw air inward at an average linear face... to wash hands, forearms, face, and neck upon each exit from the regulated areas, close to the point... this section must be provided with, and required to wear and use, a half-face filter type respirator...

Influence of source parameters on the growth of metal nanoparticles by sputter-gas-aggregation

NASA Astrophysics Data System (ADS)

Khojasteh, Malak; Kresin, Vitaly V.

2017-11-01

We describe the production of size-selected manganese nanoclusters using a magnetron sputtering/aggregation source. Since nanoparticle production is sensitive to a range of overlapping operating parameters (in particular, the sputtering discharge power, the inert gas flow rates, and the aggregation length), we focus on a detailed map of the influence of each parameter on the average nanocluster size. In this way, it is possible to identify the main contribution of each parameter to the physical processes taking place within the source. The discharge power and argon flow supply the metal vapor, and argon also plays a crucial role in the formation of condensation nuclei via three-body collisions. However, the argon flow and the discharge power have a relatively weak effect on the average nanocluster size in the exiting beam. Here the defining role is played by the source residence time, governed by the helium supply (which raises the pressure and density of the gas column inside the source, resulting in more efficient transport of nanoparticles to the exit) and by the aggregation path length.

Perspectives on dilution jet mixing. [in creating temperature patterns at combustor exits in gas turbine engines

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Srinivasan, R.

1986-01-01

A microcomputer code which displays 3-D oblique and 2-D plots of the temperature distribution downstream of jets mixing with a confined crossflow has been used to investigate the effects of varying the several independent flow and geometric parameters on the mixing. Temperature profiles calculated with this empirical model are presented to show the effects of orifice size and spacing, momentum flux ratio, density ratio, variable temperature mainstream, flow area convergence, orifice aspect ratio, and opposed and axially staged rows of jets.

Escape problem under stochastic volatility: The Heston model

NASA Astrophysics Data System (ADS)

Masoliver, Jaume; Perelló, Josep

2008-11-01

We solve the escape problem for the Heston random diffusion model from a finite interval of span L . We obtain exact expressions for the survival probability (which amounts to solving the complete escape problem) as well as for the mean exit time. We also average the volatility in order to work out the problem for the return alone regardless of volatility. We consider these results in terms of the dimensionless normal level of volatility—a ratio of the three parameters that appear in the Heston model—and analyze their form in several asymptotic limits. Thus, for instance, we show that the mean exit time grows quadratically with large spans while for small spans the growth is systematically slower, depending on the value of the normal level. We compare our results with those of the Wiener process and show that the assumption of stochastic volatility, in an apparently paradoxical way, increases survival and prolongs the escape time. We finally observe that the model is able to describe the main exit-time statistics of the Dow-Jones daily index.

Heat Transfer in a Superelliptic Transition Duct

NASA Technical Reports Server (NTRS)

Poinsatte, Philip; Thurman, Douglas; Hippensteele, Steven

2008-01-01

Local heat transfer measurements were experimentally mapped using a transient liquid-crystal heat transfer technique on the surface of a circular-to-rectangular transition duct. The transition duct had a length-to-diameter ratio of 1.5 and an exit-plane aspect ratio of 3. The crosssectional geometry was defined by the equation of a superellipse. The cross-sectional area was the same at the inlet and exit but varied up to 15 percent higher through the transition. The duct was preheated to a uniform temperature (nominally 64 C) before allowing room temperature air to be suddenly drawn through it. As the surface cooled, the resulting isothermal contours on the duct surface were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the surface temperature and time data for all points on the duct surfaces during each test. Using this surface temperature-time data together with the temperature of the air flowing through the model and the initial temperature of the model wall, the heat transfer coefficient was calculated by employing the classic one-dimensional, semi-infinite wall heat transfer conduction model. Test results are reported for inlet diameter-based Reynolds numbers ranging from 0.4x106 to 2.4x106 and two grid-generated freestream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 16 percent, which may be more typical of real engine conditions.

Hydrologic conditions and water quality in an agricultural area in Kleberg and Nueces Counties, Texas, 1996-98

USGS Publications Warehouse

Ockerman, Darwin J.; Petri, Brian L.

2001-01-01

During 1996?98, rainfall and runoff were monitored on a 49,680-acre agricultural watershed in Kleberg and Nueces Counties in South Texas. Nineteen rainfall samples were analyzed for selected nutrients, and runoff samples from 29 storms were analyzed for major ions, nutrients, and pesticides. Loads of nutrients in rainfall and loads of nutrients and pesticides in runoff were computed. For a 40,540-acre part of the watershed (lower study area), constituent loads entering the watershed in rainfall, in runoff from the upper study area, and from agricultural chemical applications to the lower study area were compared with runoff loads exiting the lower study area. Total rainfall for 1996?98 averaged 25.86 inches per year, which is less than the long-term annual average rainfall of 29.80 inches for the area. Rainfall and runoff during 1996?98 were typical of historical patterns, with periods of below average rainfall and runoff interspersed with extreme events. Five individual storms accounted for about 38 percent of the total rainfall and 94 percent of the total runoff. During the 3-year study, the total nitrogen runoff yield from the lower study area was 1.3 pounds per acre per year, compared with 49 pounds per acre per year applied as fertilizer and 3.1 pounds per acre per year from rainfall. While almost all of the fertilizer and rainfall nitrogen was ammonia and nitrate, most of the nitrogen in runoff was particulate organic nitrogen, associated with crop residue. Total nitrogen exiting the lower study area in surface-water runoff was about 2.5 percent of the nitrogen inputs (fertilizer and rainfall nitrogen). Annual deposition of total nitrogen entering the lower study area in rainfall exceeded net yields of total nitrogen exiting the watershed in runoff because most of the rainfall does not contribute to runoff. During the study, the total phosphorus runoff yield from the lower study area was 0.48 pound per acre per year compared with 4.2 pounds per acre per year applied as fertilizer and 0.03 pound per acre per year from rainfall. Twenty-one pesticides were detected in runoff with varying degrees of frequency during the study. The herbicide atrazine was detected in all runoff samples. All of the most frequently detected pesticides (atrazine, trifluralin, simazine, pendimethalin, and diuron) exhibited higher concentrations during the pre-harvest period (March? May) than during the post-harvest period (August? October). During 1996?98, an average of 0.37 pound per acre per year of atrazine was applied to the lower study area. During the same period, 0.0027 pound per acre per year of atrazine and its breakdown product deethylatrazine exited the lower study area in runoff (about 0.7 percent of the total atrazine applied to the cropland). During 1997, when heavy rainfall occurred during the months of April and May, the atrazine plus deethylatrazine exiting the lower study area was 1.8 percent of the applied atrazine. The 1996?98 average sediment yield was 610 pounds per acre per year. Sediment loads from the study area are associated with large storm events. Of the 45,300 tons of sediment transported from the study area during 1996?98 about 87 percent was transported during the three largest runoff events (April 1997, October 1997, and October 1998). Runoff-weighted average concentrations were computed for selected nutrients and pesticides. The 1996?98 runoff-weighted concentrations for total nitrogen and total phosphorus were 1.3 and 0.50 milligrams per liter, respectively. The 1996?98 runoff-weighted concentration for atrazine plus deethylatrazine was 2.7 micrograms per liter.

Polynuclear aromatic hydrocarbon and particulate emissions from two-stage combustion of polystyrene: the effects of the secondary furnace (afterburner) temperature and soot filtration.

PubMed

Wang, Jun; Richter, Henning; Howard, Jack B; Levendis, Yiannis A; Carlson, Joel

2002-02-15

Laboratory experiments were conducted in a two-stage horizontal muffle furnace in order to monitor emissions from batch combustion of polystyrene (PS) and identify conditions that minimize them. PS is a dominant component of municipal and hospital waste streams. Bench-scale combustion of small samples (0.5 g) of shredded styrofoam cups was conducted in air, using an electrically heated horizontal muffle furnace, kept at Tgas = 1000 degrees C. Upon devolatilization, combustion of the polymer took place in a diffusion flame over the sample. The gaseous combustion products were mixed with additional air in a venturi and were channeled to a secondary muffle furnace (afterburner) kept at Tgas = 900-1100 degrees C; residence time therein varied between 0.6 and 0.8 s. At the exits of the primary and the secondary furnace the emissions of CO, CO2, O2, NOx, particulates as well as volatile and semivolatile hydrocarbons, such as polycyclic aromatic hydrocarbons (PAH), were monitored. Online analyzers, gravimetric techniques, and gas chromatography coupled to mass spectrometry (GC-MS) were used. Experiments were also conducted with a high-temperature barrier filter, placed just before the exit of the primary furnace to prevent the particulates from entering into the secondary furnace. Results demonstrated the beneficial effect of the afterburner in reducing PAH concentrations, including those of mutagenic species such as benzo[a]pyrene. Concentrations of individual PAH exhibited a pronounced after burner temperature dependence, typically ranging from a small decrease at 900 degrees C to a larger degree of consumption at 1100 degrees C. Consumption of PAH was observed to be the dominant feature at 900 degrees C, while significant quantities of benzene and some of its derivatives, captured by means of carbosieve/Carbotrap adsorbents, were formed in the afterburner at a temperature of 1000 degrees C. In the primary furnace, about 30% of the mass of the initial polystyrene was converted into soot, while the total mass of PAH represented about 3% of the initial mass of combustible. The afterburner reduced the particulate (soot) emissions by only 20-30%, which indicates that once soot is formed its destruction is rather difficult because its oxidation kinetics are slow undertypical furnace conditions. Moreover, increasing the afterburnertemperature resulted in an increasing trend of soot emissions therefrom, which might indicate competition between soot oxidation and formation, with some additional formation occurring at the higher temperatures. Contrary to the limited effect of the afterburner, high-temperature filtration of the combustion effluent prior to the exit of the primary furnace allowed for effective soot oxidation inside of the ceramic filter. Filtration drastically reduced soot emissions, by more than 90%. Limited soot formation in the afterburner was again observed with increasing temperatures. The yields of both CO and CO2 were largely unaffected by the temperature of the afterburner but increased at the presence of the filter indicating oxidation therein. A previously developed kinetic model was used to identify major chemical reaction pathways involving PAH in the afterburner. The experimental data at the exit of the primary furnace was used as input to these model computations. A first evaluation of the predictive capability of the model was conducted for the case with ceramic filter and a temperature of 900 degrees C. The afterburner was approximated as a plug-flow reactor, and model predictions at a residence time of 0.8 s were compared to experimental data collected at its exit. In agreement with the experimental PAH concentration, only a minor impact of the afterburner treatment was observed for most species at 900 degrees C. OH was deduced to be the major reactant with a mole fraction about 4 orders of magnitudes higher than that of hydrogen radicals. Evidence for the need of further work on the quantitative assessment of oxidation of PAH and their radicals is given.

Bed occupancy monitoring: data processing and clinician user interface design.

PubMed

Pouliot, Melanie; Joshi, Vilas; Goubran, Rafik; Knoefel, Frank

2012-01-01

Unobtrusive and continuous monitoring of patients, especially at their place of residence, is becoming a significant part of the healthcare model. A variety of sensors are being used to monitor different patient conditions. Bed occupancy monitoring provides clinicians a quantitative measure of bed entry/exit patterns and may provide information relating to sleep quality. This paper presents a bed occupancy monitoring system using a bed pressure mat sensor. A clinical trial was performed involving 8 patients to collect bed occupancy data. The trial period for each patient ranged from 5-10 weeks. This data was analyzed using a participatory design methodology incorporating clinician feedback to obtain bed occupancy parameters. The parameters extracted include the number of bed exits per night, the bed exit weekly average (including minimum and maximum), the time of day of a particular exit, and the amount of uninterrupted bed occupancy per night. The design of a clinical user interface plays a significant role in the acceptance of such patient monitoring systems by clinicians. The clinician user interface proposed in this paper was designed to be intuitive, easy to navigate and not cause information overload. An iterative design methodology was used for the interface design. The interface design is extendible to incorporate data from multiple sensors. This allows the interface to be part of a comprehensive remote patient monitoring system.

Thermodynamic properties and theoretical rocket performance of hydrogen to 100,000 K and 1.01325 x 10 to the 8th power N/sq m

NASA Technical Reports Server (NTRS)

Patch, R. W.

1971-01-01

The composition and thermodynamic properties were calculated for 100 to 110,000 K and 1.01325 x 10 to the 2nd power to 1.01325 x 10 to the 8th power N/sq m for chemical equilibrium in the Debye-Huckel and ideal-gas approximations. Quantities obtained were the concentrations of hydrogen atoms, protons, free electrons, hydrogen molecules, negative hydrogen ions, hydrogen diatomic molecular ions, and hydrogen triatomic molecular ions, and the enthalpy, entropy, average molecular weight, specific heat at constant pressure, density, and isentropic exponent. Electronically excited states of H and H2 were included. Choked, isentropic, one-dimensional nozzle flow with shifting chemical equilibrium was calculated to the Debye-Huckel and ideal-gas approximations for stagnation temperatures from 2500 to 100,000 K. The mass flow per unit throat area and the sonic flow factor were obtained. The pressure ratio, temperature, velocity, and ideal and vacuum specific impulses at the throat and for pressure ratios as low as 0.000001 downstream were found. For high temperatures at pressures approaching 1.01325 x 10 to the 8th power N/sq m, the ideal-gas approximation was found to be inadequate for calculations of composition, precise thermodynamic properties, and precise nozzle flow. The greatest discrepancy in nozzle flow occurred in the exit temperature, which was as much as 21 percent higher when the Debye-Huckel approximation was used.

29 CFR Appendix to Subpart E of... - Exit Routes, Emergency Action Plans, and Fire Prevention Plans

Code of Federal Regulations, 2010 CFR

2010-07-01

... necessary. Essential plant operations may include the monitoring of plant power supplies, water supplies... detect fuel leaks. An example is a temperature limit switch often found on deep-fat food fryers found in...

A Plasma Model of Missile Exhaust Plumes. (Axial and Radial Conductivity Distributions for the Redeye Missile).

DTIC Science & Technology

1977-04-01

Conductivity ...... . .i 6 Relief Map of Conductivity ......... i9 7a conductivity versus Axial Position with Radial Position a a Parater...concentrations ii. pressure iii. temperature iv. velocity v. snie, number and velocity distribuions of the liquid particlas (if any are to be considered) I vi...Number = 1 vi. J• velocity = 8644 fps; Edge velocity = 10 fps vii. Jet temperature = 21160 K; Edge temperature = 278*K Also, at the exit piane, the

Species and temperature predictions in a semi-industrial MILD furnace using a non-adiabatic conditional source-term estimation formulation

NASA Astrophysics Data System (ADS)

Labahn, Jeffrey William; Devaud, Cecile

2017-05-01

A Reynolds-Averaged Navier-Stokes (RANS) simulation of the semi-industrial International Flame Research Foundation (IFRF) furnace is performed using a non-adiabatic Conditional Source-term Estimation (CSE) formulation. This represents the first time that a CSE formulation, which accounts for the effect of radiation on the conditional reaction rates, has been applied to a large scale semi-industrial furnace. The objective of the current study is to assess the capabilities of CSE to accurately reproduce the velocity field, temperature, species concentration and nitrogen oxides (NOx) emission for the IFRF furnace. The flow field is solved using the standard k-ε turbulence model and detailed chemistry is included. NOx emissions are calculated using two different methods. Predicted velocity profiles are in good agreement with the experimental data. The predicted peak temperature occurs closer to the centreline, as compared to the experimental observations, suggesting that the mixing between the fuel jet and vitiated air jet may be overestimated. Good agreement between the species concentrations, including NOx, and the experimental data is observed near the burner exit. Farther downstream, the centreline oxygen concentration is found to be underpredicted. Predicted NOx concentrations are in good agreement with experimental data when calculated using the method of Peters and Weber. The current study indicates that RANS-CSE can accurately predict the main characteristics seen in a semi-industrial IFRF furnace.

Influence of the fire location and the size of a compartment on the heat and smoke flow out of the compartment

NASA Astrophysics Data System (ADS)

Wegrzyński, Wojciech; Konecki, Marek

2018-01-01

This paper presents results of CFD and scale modelling of the flow of heat and smoke inside and outside of a compartment, in case of fire. Estimation of mass flow out of a compartment is critical, as it is the boundary condition in further considerations related to the exhaust of the smoke from a building - also in analysis related to the performance of natural ventilation in wind conditions. Both locations of the fire and the size of compartment were addressed as possible variables, which influence the mass and the temperature of smoke that leaves the room engulfed in fire. Results of the study show small to none influence of both size of the compartment and the location of the fire, on the mass flow of smoke exiting the room. On the same time, both of these parameters influence the temperature of the smoke - in larger compartments lower average temperatures of the smoke layer, but higher maximum values were observed. Results of this study may be useful also in the determination of the worst case scenarios for structural analysis, or in the investiga tion of the spread of fire through the compartment. Based on the results presented in this study, researchers can attribute an expert judgement choice of fire location, as a single scenario that is representative of a larger amount of probable scenarios.

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device.

PubMed

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-21

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device

NASA Astrophysics Data System (ADS)

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-01

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade

NASA Technical Reports Server (NTRS)

Flegel, Ashlie B.

2014-01-01

The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the three-dimensional flow field and midspan loss and turning of a two-dimensional section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, Ohio. Steady-state data were obtained for 10 incidence angles ranging from +15.8deg to -51.0deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×105 to 2.12×106. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan tota lpressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8deg and -36.7deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures.

Studying the Role of the Mitotic Exit Network in Cytokinesis.

PubMed

Foltman, Magdalena; Sanchez-Diaz, Alberto

2017-01-01

In budding yeast cells, cytokinesis is achieved by the successful division of the cytoplasm into two daughter cells, but the precise mechanisms of cell division and its regulation are still rather poorly understood. The Mitotic Exit Network (MEN) is the signaling cascade that is responsible for the release of Cdc14 phosphatase leading to the inactivation of the kinase activity associated to cyclin-dependent kinases (CDK), which drives exit from mitosis and a rapid and efficient cytokinesis. Mitotic CDK impairs the activation of MEN before anaphase, and activation of MEN in anaphase leads to the inactivation of CDK, which presents a challenge to determine the contribution that each pathway makes to the successful onset of cytokinesis. To determine CDK and MEN contribution to cytokinesis irrespectively of each other, here we present methods to induce cytokinesis after the inactivation of CDK activity in temperature sensitive mutants of the MEN pathway. An array of methods to monitor the cellular events associated with the successful cytokinesis is included.

Effects of the magnetic field gradient on the wall power deposition of Hall thrusters

NASA Astrophysics Data System (ADS)

Ding, Yongjie; Li, Peng; Zhang, Xu; Wei, Liqiu; Sun, Hezhi; Peng, Wuji; Yu, Daren

2017-04-01

The effect of the magnetic field gradient in the discharge channel of a Hall thruster on the ionization of the neutral gas and power deposition on the wall is studied through adopting the 2D-3V particle-in-cell (PIC) and Monte Carlo collisions (MCC) model. The research shows that by gradually increasing the magnetic field gradient while keeping the maximum magnetic intensity at the channel exit and the anode position unchanged, the ionization region moves towards the channel exit and then a second ionization region appears near the anode region. Meanwhile, power deposition on the walls decreases initially and then increases. To avoid power deposition on the walls produced by electrons and ions which are ionized in the second ionization region, the anode position is moved towards the channel exit as the magnetic field gradient is increased; when the anode position remains at the zero magnetic field position, power deposition on the walls decreases, which can effectively reduce the temperature and thermal load of the discharge channel.

On the Scaling Laws for Jet Noise in Subsonic and Supersonic Flow

NASA Technical Reports Server (NTRS)

Vu, Bruce; Kandula, Max

2003-01-01

The scaling laws for the simulation of noise from subsonic and ideally expanded supersonic jets are examined with regard to their applicability to deduce full scale conditions from small-scale model testing. Important parameters of scale model testing for the simulation of jet noise are identified, and the methods of estimating full-scale noise levels from simulated scale model data are addressed. The limitations of cold-jet data in estimating high-temperature supersonic jet noise levels are discussed. It is shown that the jet Mach number (jet exit velocity/sound speed at jet exit) is a more general and convenient parameter for noise scaling purposes than the ratio of jet exit velocity to ambient speed of sound. A similarity spectrum is also proposed, which accounts for jet Mach number, angle to the jet axis, and jet density ratio. The proposed spectrum reduces nearly to the well-known similarity spectra proposed by Tam for the large-scale and the fine-scale turbulence noise in the appropriate limit.

Experimental investigation on frequency characteristics of plasma synthetic jets

NASA Astrophysics Data System (ADS)

Zong, Haohua; Kotsonis, Marios

2017-11-01

The performance of a two-electrode plasma synthetic jet actuator (PSJA) is investigated for a wide range of dimensionless actuation frequencies ( f*) using high-speed phase-locked particle imaging velocimetry measurements. The jet-induced velocity fields in the axisymmetric plane are measured during both transient and steady working stages of the PSJA. When f* increases, the jet duration time (Tjet) is reduced, while the peak suction velocity (Us) increases consistently. Three integral parameters including the total expelled gas mass, impulse, and issued mechanical energy also decline considerably with increasing frequency, which is shown to relate to both the reduced cavity density and the decreasing jet duration. Theoretical analysis reveals that the mean cavity density decreases monotonically with the square root of the discharge frequency. The decreasing rate is inversely proportional to a thermal cut-off frequency ( fc, 210 Hz for the current study), which scales with the convective heat transfer coefficient between the actuator cavity walls and the cavity gas, as well as the area of the cavity internal surface. In the time-averaged velocity fields, the jet centreline velocity (U¯ c) exhibits a local maximum in the axial coordinate. The nondimensional maximum centreline velocity reduces with increasing frequency of operation. The jet spreading rate of the plasma synthetic jets (PSJs) decreases from 0.14 to 0.09 with increasing frequency. During the transient working stage of a PSJ, the exit velocity trace elapses 20 successive actuation cycles to stabilize. In contrast to the exit velocity, approximately 130 cycles are needed for the mean cavity density/temperature to reach steady values.

RSRM nozzle fixed housing cooldown test

NASA Technical Reports Server (NTRS)

Bolieau, D. J.

1989-01-01

Flight 5 aft segments with nozzles were exposed to -17 F temperatures while awaiting shipment to KSC in February, 1989. No records were found which show that any previous nozzles were exposed to air temperatures as low as those seen by the Flight 5 nozzles. Thermal analysis shows that the temperature of the fixed housing, and forward and aft exit cone components dropped as low as -10 F. Structural analysis of the nozzles at these low temperatures show the forward and aft exit cone adhesive bonds to have a positive margin of safety, based on a 2.0 safety factor. These analyses show the normal and shear stresses in the fixed housing bond as low values. However, the hoop and meridinal stresses were predicted to be in the 4000 psi range; the failure stress allowable of EA913NA adhesive at -7 F. If the bonds did break in directions perpendicular to the surfaces, called bond crazing, no normal bond strength would be lost. Testing was conducted in two phases, showing that no degradation to the adhesive bonds occurred while the Flight 5 nozzles were subjected to subzero temperatures. The results of these tests are documented. Phase 1 testing cooled a full-scale RSRM insulated fixed housing to -13 F, with extensive bondline inspections. Phase 2 testing cooled the witness panel adhesive tensile buttions to -13 F, with failure strengths recorded before, during, and after the cooldown.

Quasi 1-D Analysis of a Circular, Compressible, Turbulent Jet Laden with Water Droplets. Appendix C

NASA Technical Reports Server (NTRS)

2001-01-01

Recent experimental studies indicate that presence of small amount of liquid droplets reduces the Overall Sound Pressure Level (OASPL) of a jet. Present study is aimed at numerically investigating the effect of liquid particles on the overall flow quantities of a heated, compressible round jet. The jet is assumed perfectly expanded. A quasi-1D model was developed for this purpose which uses area-averaged quantities that satisfy integral conservation equations. Special attention is given to represent the early development region since it is acoustically important. Approximate velocity and temperature profiles were assumed in this region to evaluate entrainment rate. Experimental correlations were used to obtain spreading rate of shear layer. The base flow thus obtained is then laden with water droplets at the exit of the nozzle. Mass, momentum and energy coupling between the two phases is represented using empirical relations. Droplet size and mass loading are varied to observe their effect on flow variables.

Nuclear design of a vapor core reactor for space nuclear propulsion

NASA Astrophysics Data System (ADS)

Dugan, Edward T.; Watanabe, Yoichi; Kuras, Stephen A.; Maya, Isaac; Diaz, Nils J.

1993-01-01

Neutronic analysis methodology and results are presented for the nuclear design of a vapor core reactor for space nuclear propulsion. The Nuclear Vapor Thermal Reactor (NVTR) Rocket Engine uses modified NERVA geometry and systems which the solid fuel replaced by uranium tetrafluoride vapor. The NVTR is an intermediate term gas core thermal rocket engine with specific impulse in the range of 1000-1200 seconds; a thrust of 75,000 lbs for a hydrogen flow rate of 30 kg/s; average core exit temperatures of 3100 K to 3400 K; and reactor thermal powers of 1400 to 1800 MW. Initial calculations were performed on epithermal NVTRs using ZrC fuel elements. Studies are now directed at thermal NVTRs that use fuel elements made of C-C composite. The large ZrC-moderated reactors resulted in thrust-to-weight ratios of only 1 to 2; the compact C-C composite systems yield thrust-to-weight ratios of 3 to 5.

Door openings in the operating room are associated with increased environmental contamination.

PubMed

Perez, Priscilla; Holloway, Julia; Ehrenfeld, Lucy; Cohen, Susan; Cunningham, Linda; Miley, Gerald B; Hollenbeck, Brian L

2018-05-04

Door openings in the operating room (OR) have been hypothesized to increase OR environmental contamination. This study measured average colony-forming units (CFU) in the OR as a function of door openings and other potentially important variables. Bacterial settle plates were placed inside and outside of laminar airflow (LAF) by both exit doors, on the instrument table, and on the back instrument table (if applicable) for 48 orthopedic and general surgery procedures. CFU data were paired to Staphylococcus aureus colonization status, door openings, surgery duration, time of day, OR location, number of staff, use of warming devices, temperature, and humidity. The number of door openings in the OR and surgery duration were significantly associated with increased CFU in the OR overall and outside of LAF. However, under LAF conditions, only the number of OR personnel was significantly associated with increased CFU. Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Assessment of Reduced-Kinetics Mechanisms for Combustion of Jet Fuel in CFD Applications

NASA Technical Reports Server (NTRS)

Ajmani, Kumud; Kundu, Krihna P.; Yungster, Shaye J.

2014-01-01

A computational effort was undertaken to analyze the details of fluid flow in Lean-Direct Injection (LDI) combustors for next-generation LDI design. The National Combustor Code (NCC) was used to perform reacting flow computations on single-element LDI injector configurations. The feasibility of using a reduced chemical-kinetics approach, which optimizes the reaction rates and species to model the emissions characteristics typical of lean-burning gas-turbine combustors, was assessed. The assessments were performed with Reynolds- Averaged Navier-Stokes (RANS) and Time-Filtered Navier Stokes (TFNS) time-integration, with a Lagrangian spray model with the NCC code. The NCC predictions for EINOx and combustor exit temperature were compared with experimental data for two different single-element LDI injector configurations, with 60deg and 45deg axially swept swirler vanes. The effects of turbulence-chemistry interaction on the predicted flow in a typical LDI combustor were studied with detailed comparisons of NCC TFNS with experimental data.

A three-dimensional study of the glottal jet

NASA Astrophysics Data System (ADS)

Krebs, F.; Silva, F.; Sciamarella, D.; Artana, G.

2012-05-01

This work builds upon the efforts to characterize the three-dimensional features of the glottal jet during vocal fold vibration. The study uses a Stereoscopic Particle Image Velocimetry setup on a self-oscillating physical model of the vocal folds with a uniform vocal tract. Time averages are documented and analyzed within the framework given by observations reported for jets exiting elongated nozzles. Phase averages are locked to the audio signal and used to obtain a volumetric reconstruction of the jet. From this reconstruction, the intra-cycle dynamics of the jet axis switching is disclosed.

Dynamics of Economic Well-Being: Poverty 1996-1999. Current Population Reports.

ERIC Educational Resources Information Center

Iceland, John

This report examines patterns of poverty using seven different measures: average monthly poverty, episodic poverty, chronic poverty, annual poverty, poverty spells, poverty entry rates, and poverty exit rates. Data come from the 1996 panel of the Survey of Income and Program Participation (SIPP) and reflect the dynamics of poverty from 1996-1999.…

40 CFR 60.705 - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... readings, heat content determinations, flow rate measurements, and exit velocity determinations made during... mass flow measured at least every 15 minutes and averaged over the same time period of the performance... of the flow indication specified under § 60.703(a)(2)(i), § 60.703(b)(2)(i) and § 60.703(c)(1)(i), as...

Bias and uncertainty in the absorption emission measurement of atomic sodium density in the SSME exit plane

NASA Technical Reports Server (NTRS)

Bauman, Leslie E.

1990-01-01

The measurement of atomic sodium concentration in the TTB 019 firing of April 1990 is significant in that it represents the first measurement of density at the exit plane of the space shuttle main engine. The knowledge of the sodium density, combined with the certainty that the exit plane of the plume is optically thin at the sodium D-line wavelengths, provides essential information for evaluation of diagnostic techniques using sodium atoms, such as resonant Doppler velocimetry for temperature, pressure, and velocity through high resolution fluorescent lineshape analysis. The technique used for the sodium atom line transmission (SALT) measurements is that of resonant absorption emission using a hollow cathode lamp as the reference source. Through the use of two-dimensional kinetic (TDK) predictions of temperature and density for the flight engine case and radiative transfer calculations, this line-of-sight spectrally integrated transmission indicates a sodium atom concentration, i.e., mole fraction, of 0.91e-10. The subject of this paper is the assumptions and measurement uncertainties tied into the calculation. Because of the narrow shape of the source emission, the uncertainties in the absorption profile could introduce considerable bias in the measurement. The following were investigated: (1) the inclusion of hyperfine splitting of the D-lines in the calculation; (2) the use of the flight engine predictions of plume temperature and density versus those for the large throat engine; (3) the assumption of a Gaussian, i.e., Doppler, distribution for the source radiance with a temperature of 400 K; (4) the use of atomic collisional shift and width values for the work by Jongerius; and (5) a Doppler shift for a 7 degree outward velocity vector at the plume edge. Also included in the study was the bias introduced by an uncertainty in the measurement of the D1/D2 line ratio in the source.

The erosion/corrosion of small superalloy turbine rotors operating in the effluent of a PFB coal combustor

NASA Technical Reports Server (NTRS)

Zellars, G. R.; Benfold, S. M.; Rowe, A. P.; Lowell, C. E.

1979-01-01

Superalloy turbine rotors in a single stage turbine with 6 percent partial admittance were operated in the effluent of a pressurized fluidized bed coal combustor for up to 164 hours. Total mass flow was 300 kg/hr and average particulate loadings ranged from 600 to 2800 ppm for several coal/sorbent combinations. A 5.5 atm turbine inlet gas pressure and inlet gas temperatures from 700 to 800 C yielded absolute gas velocities at the stator exit of about 500 m/s. The angular rotation speed (40,000 rpm) of the six inch diameter rotors was equivalent to a tip speed of about 300 m/s, and average gas velocities relative to the rotating surface ranged from 260 to 330 m/s at mean radius. The rotor erosion pattern reflects heavy particle separation with severe (5 to 500 cm/yr) erosion at the leading edge, pressure side center, and suction side trailing edge at the tip. The erosion distribution pattern provides a spectrum of erosion/oxidation/deposition as a function of blade position. This spectrum includes enhanced oxidation (10 to 100 x air), mixed oxides in exposed depletion zones, sulfur rich oxides in deposition zones, and rugged areas of erosive oxide removal.

Theoretical and Experimental Particle Velocity in Cold Spray

NASA Astrophysics Data System (ADS)

Champagne, Victor K.; Helfritch, Dennis J.; Dinavahi, Surya P. G.; Leyman, Phillip F.

2011-03-01

In an effort to corroborate theoretical and experimental techniques used for cold spray particle velocity analysis, two theoretical and one experimental methods were used to analyze the operation of a nozzle accelerating aluminum particles in nitrogen gas. Two-dimensional (2D) axi-symmetric computations of the flow through the nozzle were performed using the Reynolds averaged Navier-Stokes code in a computational fluid dynamics platform. 1D, isentropic, gas-dynamic equations were solved for the same nozzle geometry and initial conditions. Finally, the velocities of particles exiting a nozzle of the same geometry and operated at the same initial conditions were measured by a dual-slit velocimeter. Exit plume particle velocities as determined by the three methods compared reasonably well, and differences could be attributed to frictional and particle distribution effects.

Motivating signage prompts safety belt use among drivers exiting senior communities.

PubMed

Cox, B S; Cox, A B; Cox, D J

2000-01-01

Senior drivers are vulnerable to automobile crashes and subsequent injury and death. Safety belts reduce health risks associated with auto crashes. Therefore, it is important to encourage senior drivers to wear safety belts while driving. Using an AB design, replicated five times, we evaluated the short- and long-term effects of a sign with the message "BUCKLE UP, STAY SAFE" attached to a stop sign at the exits of five different senior communities. Safety belt use was stable during two pretreatment assessments averaged across the five sites and 250 drivers (72% and 68% usage), but significantly increased following installation of these signs (94% usage). Six months after installation of the signs, the effect persisted (88% usage). Use of such signs may be a cost-effective way of promoting safety belt use.

Comparative Studies of the Supersonic Jet Noise Generated by Rectangular and Axisymmetric Nozzles

DOT National Transportation Integrated Search

1973-06-01

The main purpose of this study is to develop experimental scaling laws useful for predicting the overall sound power of supersonic jets operating under a range of high stagnation temperatures and pressures and under various exit Mach numbers. A shock...

Total spectral distributions from Hawking radiation

NASA Astrophysics Data System (ADS)

Broda, Bogusław

2017-11-01

Taking into account the time dependence of the Hawking temperature and finite evaporation time of the black hole, the total spectral distributions of the radiant energy and of the number of particles have been explicitly calculated and compared to their temporary (initial) blackbody counterparts (spectral exitances).

Behavioral thermoregulation in Hemigrapsus nudus, the amphibious purple shore crab.

PubMed

McGaw, I J

2003-02-01

The thermoregulatory behavior of Hemigrapsus nudus, the amphibious purple shore crab, was examined in both aquatic and aerial environments. Crabs warmed and cooled more rapidly in water than in air. Acclimation in water of 16 degrees C (summer temperatures) raised the critical thermal maximum temperature (CTMax); acclimation in water of 10 degrees C (winter temperatures) lowered the critical thermal minimum temperature (CTMin). The changes occurred in both water and air. However, these survival regimes did not reflect the thermal preferences of the animals. In water, the thermal preference of crabs acclimated to 16 degrees C was 14.6 degrees C, and they avoided water warmer than 25.5 degrees C. These values were significantly lower than those of the crabs acclimated to 10 degrees C; these animals demonstrated temperature preferences for water that was 17 degrees C, and they avoided water that was warmer than 26.9 degrees C. This temperature preference was also exhibited in air, where 10 degrees C acclimated crabs exited from under rocks at a temperature that was 3.2 degrees C higher than that at which the 16 degrees C acclimated animals responded. This behavioral pattern was possibly due to a decreased thermal tolerance of 16 degrees C acclimated crabs, related with the molting process. H. nudus was better able to survive prolonged exposure to cold temperatures than to warm temperatures, and there was a trend towards lower exit temperatures with the lower acclimation (10 degrees C) temperature. Using a complex series of behaviors, the crabs were able to precisely control body temperature independent of the medium, by shuttling between air and water. The time spent in either air or water was influenced more strongly by the temperature than by the medium. In the field, this species may experience ranges in temperatures of up to 20 degrees C; however, it is able to utilize thermal microhabitats underneath rocks to maintain its body temperature within fairly narrow limits.

Simultaneous Temperature and Velocity Measurements in a Large-Scale, Supersonic, Heated Jet

NASA Technical Reports Server (NTRS)

Danehy, P. M.; Magnotti, G.; Bivolaru, D.; Tedder, S.; Cutler, A. D.

2008-01-01

Two laser-based measurement techniques have been used to characterize an axisymmetric, combustion-heated supersonic jet issuing into static room air. The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) measurement technique measured temperature and concentration while the interferometric Rayleigh scattering (IRS) method simultaneously measured two components of velocity. This paper reports a preliminary analysis of CARS-IRS temperature and velocity measurements from selected measurement locations. The temperature measurements show that the temperature along the jet axis remains constant while dropping off radially. The velocity measurements show that the nozzle exit velocity fluctuations are about 3% of the maximum velocity in the flow.

Modelling hydrological conditions in the maritime forest region of south-western Nova Scotia

NASA Astrophysics Data System (ADS)

Yanni, Shelagh; Keys, Kevin; Meng, Fan-Rui; Yin, Xiwei; Clair, Tom; Arp, Paul A.

2000-02-01

Hydrological processes and conditions were quantified for the Mersey River Basin (two basins: one exiting below Mill Falls, and one exiting below George Lake), the Roger's Brook Basin, Moosepit Brook, and for other selected locations at and near Kejimkujik National Park in Nova Scotia, Canada, from 1967 to 1990. Addressed variables included precipitation (rain, snow, fog), air temperature, stream discharge, snowpack accumulations, throughfall, soil and subsoil moisture, soil temperature and soil frost, at a monthly resolution. It was found that monthly per hectare stream discharge was essentially independent of catchment area from <20 km2 to more than 1000 km2. The forest hydrology model ForHyM2 was used to simulate monthly rates of stream discharge, throughfall and snowpack water equivalents for mature forest conditions. These simulations were in good agreement with the historical records once the contributions of fog and mist to the area-wide water budget were taken into account, each on a monthly basis. The resulting simulations establish a hydrologically consistent, continuous, comprehensive and partially verified record for basin-wide outcomes for all major hydrological processes and conditions, be these related to stream discharge, soil moisture, soil temperature, snowpack accumulations, soil frost, throughfall, interception and soil percolation.

Solar heat receiver

DOEpatents

Hunt, Arlon J.; Hansen, Leif J.; Evans, David B.

1985-01-01

A receiver for converting solar energy to heat a gas to temperatures from 700.degree.-900.degree. C. The receiver is formed to minimize impingement of radiation on the walls and to provide maximum heating at and near the entry of the gas exit. Also, the receiver is formed to provide controlled movement of the gas to be heated to minimize wall temperatures. The receiver is designed for use with gas containing fine heat absorbing particles, such as carbon particles.

Radio occultation measurements of Pluto's neutral atmosphere with New Horizons

NASA Astrophysics Data System (ADS)

Hinson, D. P.; Linscott, I. R.; Young, L. A.; Tyler, G. L.; Stern, S. A.; Beyer, R. A.; Bird, M. K.; Ennico, K.; Gladstone, G. R.; Olkin, C. B.; Pätzold, M.; Schenk, P. M.; Strobel, D. F.; Summers, M. E.; Weaver, H. A.; Woods, W. W.

2017-07-01

On 14 July 2015 New Horizons performed a radio occultation (RO) that sounded Pluto's atmosphere down to the surface. The sensitivity of the measurements was enhanced by a unique configuration of ground equipment and spacecraft instrumentation. Signals were transmitted simultaneously by four antennas of the NASA Deep Space Network, each radiating 20 kW at a wavelength of 4.2 cm. The polarization was right circular for one pair of signals and left circular for the other pair. New Horizons received the four signals and separated them by polarization for processing by two independent receivers, each referenced to a different ultra-stable oscillator. The two data streams were digitized, filtered, and stored on the spacecraft for later transmission to Earth. The results reported here are the first to utilize the complete set of observations. We calibrated each signal to remove effects not associated with Pluto's atmosphere, including the limb diffraction pattern. We then applied a specialized method of analysis to retrieve profiles of number density, pressure, and temperature from the combined phase measurements. Occultation entry sounded the atmosphere at sunset at 193.5°E, 17.0°S - on the southeast margin of an ice-filled basin known informally as Sputnik Planitia (SP); occultation exit occurred at sunrise at 15.7°E, 15.1°N - near the center of the Charon-facing hemisphere. Above 1215 km radius (∼25 km altitude) there is no discernible difference between the measurements at entry and exit, and the RO profiles are consistent with results derived from ground-based stellar occultation measurements. At lower altitudes the RO measurements reveal horizontal variations in atmospheric structure that had not been observed previously, and they are the first to reach the ground. The entry profile has a strong temperature inversion that ends 3.5 km above the surface, and the temperature in the cold boundary layer beneath the inversion is nearly constant, 38.9 ± 2.1 K, and close to the saturation temperature of N2. The exit profile has a much weaker inversion that extends all the way to the ground, where the air temperature is 51.6 ± 3.8 K. Three factors appear to be responsible for the presence of a cold boundary layer in the entry profile (Forget et al., 2017): a substantial diurnal cycle of sublimation and condensation of N2 ice in SP, the local time of the RO observation, and confinement within SP by the surrounding topography and katabatic winds. We have also determined the surface pressure and the local radius at both entry and exit. The best pressure reference is the mean value: 11.5 ± 0.7 microbar at 1189.9 ± 0.2 km.

40 CFR 60.613 - Monitoring of emissions and operations.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., photoionization, or thermal conductivity, each equipped with a continuous recorder. (2) Where a condenser is the final recovery device in a recovery system: (i) A condenser exit (product side) temperature monitoring... incinerator, boiler, process heater, or flare; or recovery devices other than an absorber, condenser, or...

The Exit Gradient As a Measure of Groundwater Dependency of Watershed Ecosystem Services

NASA Astrophysics Data System (ADS)

Faulkner, B. R.; Canfield, T. J.; Justin, G. F.

2014-12-01

Flux of groundwater to surface water is often of great interest for the determination of the groundwater dependency of ecosystem services, such as maintenance of wetlands and of baseflow as a contributor to stream channel storage. It is difficult to measure. Most methods are based on coarse mass balance estimates or seepage meters. One drawback of these methods is they are not entirely spatially explicit. The exit gradient is commonly used in engineering studies of hydraulic structures affected by groundwater flow. It can be simply defined in the groundwater modeling context as the ratio of the difference between the computed head and the land surface elevation, for each computational cell, to the thickness of the cell, as it varies in space. When combined with calibrated groundwater flow models, it also has the potential to be useful in watershed scale evaluations of groundwater dependency in a spatially explicit way. We have taken advantage of calibrated models for the Calapooia watershed, Oregon, to map exit gradients for the watershed. Streams in the Calapooia are hydraulically well connected with groundwater. Not surprisingly, we found large variations in exit gradients between wet and dry season model runs, supporting the notion of stream expansion, as observed in the field, which may have a substantial influence on water quality. We have mapped the exit gradients in the wet and dry seasons, and compared them to regions which have been mapped in wetland surveys. Those classified as Palustrine types fell largest in the area of contribution from groundwater. In many cases, substantially high exit gradients, even on average, did not correspond to mapped wetland areas, yet nutrient retention ecosystem services may still be playing a role in these areas. The results also reinforce the notion of the importance of baseflow to maintenance of stream flow, even in the dry summer season in this Temperate/Mediterranean climate. Exit gradient mapping is a simple, yet potentially very useful and underutilized tool for measuring groundwater dependency in watershed scale ecosystem services studies, and could potentially be used to predict effects due to groundwater stresses resulting from water withdrawals. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

Effect of impinging plate geometry on the self-excitation of subsonic impinging jets

NASA Astrophysics Data System (ADS)

Vinoth, B. R.; Rathakrishnan, E.

2011-11-01

In the generation of discrete tones by subsonic impinging jets, there exists a difference of opinion as how the feedback is achieved, i.e., the path of the feedback acoustic waves is whether inside the jet or outside the jet? The only available model (Tam and Ahuja model) for the prediction of an average subsonic jet impingement tone frequency assumes that the upstream part of the feedback loop is closed by an upstream propagating neutral wave of the jet. But, there is no information about the plate geometry in the model. The present study aims at understanding the effect of the plate geometry (size and co-axial hole in the plate) on the self-excitation process of subsonic impinging jets and the path of the acoustic feedback to the nozzle exit. The present results show that there is no effect of plate diameter on the frequency of the self-excitation. A new type of tones is generated for plates with co-axial hole (hole diameter is equal to nozzle exit diameter) for Mach numbers 0.9 and 0.95, in addition to the axisymmetric and helical mode tones observed for plates without co-axial hole. The stability results show that the Strouhal number of the least dispersive upstream propagating neutral waves match with the average Strouhal number of the new tones observed in the present experiments. The present study extends the validity of the model of Tam and Ahuja to a plate with co-axial hole (annular plate) and by doing so, we indirectly confirmed that the major acoustic feedback path to the nozzle exit is inside the jet.

Conceptual design for an electron-beam heated hypersonic wind tunnel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipinski, R.J.; Kensek, R.P.

1997-07-01

There is a need for hypersonic wind-tunnel testing at about mach 10 and above using natural air and simulating temperatures and pressures which are prototypic of flight at 50 km altitude or below. With traditional wind-tunnel techniques, gas cooling during expansion results in exit temperatures which are too low. Miles, et al., have proposed overcoming this difficulty by heating the air with a laser beam as it expands in the wind-tunnel nozzle. This report discusses an alternative option of using a high-power electron beam to heat the air as it expands. In the e-beam heating concept, the electron beam ismore » injected into the wind-tunnel nozzle near the exit and then is guided upstream toward the nozzle throat by a strong axial magnetic field. The beam deposits most of its power in the dense air near the throat where the expansion rate is greatest. A conceptual design is presented for a large-scale system which achieves Mach 14 for 0.1 seconds with an exit diameter of 2.8 meters. It requires 450 MW of electron beam power (5 MeV at 90 A). The guiding field is 500 G for most of the transport length and increases to 100 kG near the throat to converge the beam to a 1.0-cm diameter. The beam generator is a DC accelerator using a Marx bank (of capacitors) and a diode stack with a hot cathode. 14 refs. 38 figs., 9 tabs.« less

An Empirical Jet-Surface Interaction Noise Model with Temperature and Nozzle Aspect Ratio Effects

NASA Technical Reports Server (NTRS)

Brown, Cliff

2015-01-01

An empirical model for jet-surface interaction (JSI) noise produced by a round jet near a flat plate is described and the resulting model evaluated. The model covers unheated and hot jet conditions (1 less than or equal to jet total temperature ratio less than or equal to 2.7) in the subsonic range (0.5 less than or equal to M(sub a) less than or equal to 0.9), surface lengths 0.6 less than or equal to (axial distance from jet exit to surface trailing edge (inches)/nozzle exit diameter) less than or equal to 10, and surface standoff distances (0 less than or equal to (radial distance from jet lipline to surface (inches)/axial distance from jet exit to surface trailing edge (inches)) less than or equal to 1) using only second-order polynomials to provide predictable behavior. The JSI noise model is combined with an existing jet mixing noise model to produce exhaust noise predictions. Fit quality metrics and comparisons to between the predicted and experimental data indicate that the model is suitable for many system level studies. A first-order correction to the JSI source model that accounts for the effect of nozzle aspect ratio is also explored. This correction is based on changes to the potential core length and frequency scaling associated with rectangular nozzles up to 8:1 aspect ratio. However, more work is needed to refine these findings into a formal model.

Effect of Heating on Turbulent Density Fluctuations and Noise Generation From High Speed Jets

NASA Technical Reports Server (NTRS)

Panda, Jayanta; Seasholtz, Richard G.; Elam, Kristie A.; Mielke, Amy F.; Eck, Dennis G.

2004-01-01

Heated jets in a wide range of temperature ratios (TR), and acoustic Mach numbers (Ma) were investigated experimentally using far field microphones and a molecular Rayleigh scattering technique. The latter provided density fluctuations measurements. Two sets of operating conditions were considered: (1) TR was varied between 0.84 and 2.7 while Ma was fixed at 0.9; (2) Ma was varied between 0.6 and 1.48, while TR was fixed at 2.27. The implementation of the molecular Rayleigh scattering technique required dust removal and usage of a hydrogen combustor to avoid soot particles. Time averaged density measurements in the first set of data showed differences in the peripheral density shear layers between the unheated and heated jets. The nozzle exit shear layer showed increased turbulence level with increased plume temperature. Nevertheless, further downstream the density fluctuations spectra are found to be nearly identical for all Mach number and temperature ratio conditions. To determine noise sources a correlation study between plume density fluctuations and far field sound pressure fluctuations was conducted. For all jets the core region beyond the end of the potential flow was found to be the strongest noise source. Except for an isothermal jet, the correlations did not differ significantly with increasing temperature ratio. The isothermal jet created little density fluctuations. Although the far field noise from this jet did not show any exceptional trend, the flow-sound correlations were very low. This indicated that the density fluctuations only acted as a "tracer parameter" for the noise sources.

Use of Biochar to sequester nutrients from dairy manure lagoons

USDA-ARS?s Scientific Manuscript database

We are developing technology to utilize dairy waste as an alternative energy and fertilizer source. The fiber component exiting a GHD™ Plugged Flow anaerobic digester as well as feedstocks from softwood sources were used to produce bio-gas or bio-oil under low temperature pyrolysis, the co-product, ...

Characterization of Centrifugally-Loaded Flame Migration for Ultra-Compact Combustors

DTIC Science & Technology

2011-10-01

11 T04 combustor exit temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Q b combustor heat addition...11 Q ab afterburner heat addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11...the mass flow rates, with heat addition, lead to reaching a specific g-load. In addition to varying g-load, a larger scale UCC will require a

Monitoring Spatiotemporal Changes of Heat Island in Babol City due to Land Use Changes

NASA Astrophysics Data System (ADS)

Alavi Panah, S. K.; Kiavarz Mogaddam, M.; Karimi Firozjaei, M.

2017-09-01

Urban heat island is one of the most vital environmental risks in urban areas. The advent of remote sensing technology provides better visibility due to the integrated view, low-cost, fast and effective way to study and monitor environmental and humanistic changes. The aim of this study is a spatiotemporal evaluation of land use changes and the heat island in the time period of 1985-2015 for the studied area in the city of Babol. For this purpose, multi-temporal Landsat images were used in this study. For calculating the land surface temperature (LST), single-channel and maximum likelihood algorithms were used, to classify Images. Therefore, land use changes and LST were examined, and thereby the relationship between land-use changes was analyzed with the normalized LST. By using the average and standard deviation of normalized thermal images, the area was divided into five temperature categories, inter alia, very low, low, medium, high and very high and then, the heat island changes in the studied time period were investigated. The results indicate that land use changes for built-up lands increased by 92%, and a noticeable decrease was observed for agricultural lands. The Built-up land changes trend has direct relation with the trend of normalized surface temperature changes. Low and very low-temperature categories which follow a decreasing trend, are related to lands far away from the city. Also, high and very high-temperature categories whose areas increase annually, are adjacent to the city center and exit ways of the town. The results emphasize on the importance of attention of urban planners and managers to the urban heat island as an environmental risk.

Solar heat receiver

DOEpatents

Hunt, A.J.; Hansen, L.J.; Evans, D.B.

1982-09-29

A receiver is described for converting solar energy to heat a gas to temperatures from 700 to 900/sup 0/C. The receiver is formed to minimize impingement of radiation on the walls and to provide maximum heating at and near the entry of the gas exit. Also, the receiver is formed to provide controlled movement of the gas to be heated to minimize wall temperatures. The receiver is designed for use with gas containing fine heat absorbing particles, such as carbon particles.

Self-actuated nuclear reactor shutdown system using induction pump to facilitate sensing of core coolant temperature

DOEpatents

Sievers, Robert K.; Cooper, Martin H.; Tupper, Robert B.

1987-01-01

A self-actuated shutdown system incorporated into a reactivity control assembly in a nuclear reactor includes pumping means for creating an auxiliary downward flow of a portion of the heated coolant exiting from the fuel assemblies disposed adjacent to the control assembly. The shutdown system includes a hollow tubular member which extends through the outlet of the control assembly top nozzle so as to define an outer annular flow channel through the top nozzle outlet separate from an inner flow channel for primary coolant flow through the control assembly. Also, a latching mechanism is disposed in an inner duct of the control assembly and is operable for holding absorber bundles in a raised position in the control assembly and for releasing them to drop them into the core of the reactor for shutdown purposes. The latching mechanism has an inner flow passage extending between and in flow communication with the absorber bundles and the inner flow channel of the top nozzle for accommodating primary coolant flow upwardly through the control assembly. Also, an outer flow passage separate from the inner flow passage extends through the latching mechanism between and in flow communication with the inner duct and the outer flow channel of the top nozzle for accommodating inflow of a portion of the heated coolant from the adjacent fuel assemblies. The latching mechanism contains a magnetic material sensitive to temperature and operable to cause mating or latching together of the components of the latching mechanism when the temperature sensed is below a known temperature and unmating or unlatching thereof when the temperature sensed is above a given temperature. The temperature sensitive magnetic material is positioned in communication with the heated coolant flow through the outer flow passage for directly sensing the temperature thereof. Finally, the pumping means includes a jet induction pump nozzle and diffuser disposed adjacent the bottom nozzle of the control assembly and in flow communication with the inlet thereof. The pump nozzle is operable to create an upward driving flow of primary coolant through the pump diffuser and then to the absorber bundles. The upward driving flow of primary coolant, in turn, creates a suction head within the outer flow channel of the top nozzle and thereby an auxiliary downward flow of the heated coolant portion exiting from the upper end of the adjacent fuel assemblies through the outer flow channel to the pump nozzle via the outer flow passage of the latching mechanism and an annular space between the outer and inner spaced ducts of the control assembly housing. The temperature of the heated coolant exiting from the adjacent fuel assemblies can thereby be sensed directly by the temperature sensitive magnetic material in the latching mechanism.

Comparison of measurement data at the impeller exit of a centrifugal compressor measured with both pneumatic and fast-response probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roduner, C.; Koeppel, P.; Kupferschmied, P.

1999-07-01

The main goal of these investigations was the refined measurement of unsteady high speed flow in a centrifugal compressor using the advanced FRAP{reg_sign} fast-response aerodynamic probe system. The present contribution focuses on the impeller exit region and shows critical comparisons between fast-response (time-resolving) and conventional pneumatic probe measurement results. Three probes of identical geometry (one fast and two pneumatic) were used to perform wall-to-wall traverses close to impeller exit. The data shown refer to a single running condition near the best point of the stage. The mass flow obtained from different probe measurements and from the standard orifice measurement weremore » compared. Stage work obtained from temperature rise measured with a FRAP{reg_sign} probe and from impeller outlet velocity vectors fields by using Euler`s turbine equation are presented. The comparison in terms of velocity magnitude and angle distribution is quite satisfactory, indicating the superior DC measurement capabilities of the fast-response probe system.« less

Mixture-Fraction Measurements with Femtosecond-Laser Electronic-Excitation Tagging

NASA Technical Reports Server (NTRS)

Halls, Benjamin R.; Jiang, Naibo; Gord, James R.; Danehy, Paul M.; Roy, Sukesh

2017-01-01

Tracer-free mixture-fraction measurements were demonstrated in a jet using femtosecond-laser electronic-excitation tagging. Measurements were conducted across a turbulent jet at several downstream locations both in a pure-nitrogen jet exiting into an air-nitrogen mixture and in a jet containing an air-nitrogen mixture exiting into pure nitrogen. The signal was calibrated with known concentrations of oxygen in nitrogen. The spatial resolution of the measurement was approx.180 microns. The measurement uncertainty ranged from 5% to 15%, depending on the mixture fraction and location within the beam, under constant temperature and pressure conditions. The measurements agree with a mixture fraction of unity within the potential core of the jet and transition to the self-similar region.

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2015-01-01

The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

NASA Low-Speed Centrifugal Compressor for Fundamental Research

NASA Technical Reports Server (NTRS)

Wood, J. R.; Adam, P. W.; Buggele, A. E.

1983-01-01

A centrifugal compressor facility being built by the NASA Lewis Research Center is described; its purpose is to obtain benchmark experimental data for internal flow code verification and modeling. The facility will be heavily instrumented with standard pressure and temperature probes and have provisions for flow visualization and laser Doppler velocimetry. The facility will accommodate rotational speeds to 2400 rpm and will be rated at pressures to 1.25 atm. The initial compressor stage for testing is geometrically and dynamically representative of modern high-performance stages with the exception of Mach number levels. Design exit tip speed for the initial stage is 500 ft/sec with a pressure ratio of 1.17. The rotor exit backsweep is 55 deg from radial.

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2014-01-01

The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90º-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105% of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100% design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

MHD mixed convection flow and heat transfer in an open C-shaped enclosure using water-copper oxide nanofluid

NASA Astrophysics Data System (ADS)

Armaghani, T.; Esmaeili, H.; Mohammadpoor, Y. A.; Pop, I.

2018-01-01

In this paper, the steady mixed convection flow and heat transfer of water-copper oxide nanofluid in an open C-shaped enclosure is investigated numerically. The enclosure is under constant magnetic field. Effects of Richardson number, magnetic and nanofluid volume fraction parameters are studied and discussed. The nanofluid with a cold temperature of T C and a velocity of u c enters the enclosure from the top right corner and exits from the bottom right corner. The vertical wall of the left side is subjected to a hot and constant temperature T h . Also, other walls are insulated. It is found that the heat transfer is increased via increasing the Hartmann and Reynolds numbers. For low Reynolds numbers, the enhances of the Hartman number leads to a slightly increases of the average Nusselt number, but for high Reynolds numbers, the average Nusselt number gets an ascending trend and the increase in the Hartmann number shows its effect more pronounced. Also, with increase in Ri, the effect of nanofluid on the heat transfer increases. Due to practical impotence, the study of mixed convection heat transfer in enclosures and various shaped of cavities has attracted remarkable attentions in the past few decades. Significant applications of the mixed convection flow can be found in atmospheric flows, solar energy storage, heat exchangers, lubrication technology, drying technologies, cooling of the electronic devices, etc. The present results are original and new for the problem of MHD mixed convection flow and heat transfer in an open C-shaped enclosure using water-copper oxide nanofluid. Comparison of the obtained results with those from the open literature (Mahmoodi et al. [24]) is acceptable.

MHD mixed convection flow and heat transfer in an open C-shaped enclosure using water-copper oxide nanofluid

NASA Astrophysics Data System (ADS)

Armaghani, T.; Esmaeili, H.; Mohammadpoor, Y. A.; Pop, I.

2018-06-01

In this paper, the steady mixed convection flow and heat transfer of water-copper oxide nanofluid in an open C-shaped enclosure is investigated numerically. The enclosure is under constant magnetic field. Effects of Richardson number, magnetic and nanofluid volume fraction parameters are studied and discussed. The nanofluid with a cold temperature of T C and a velocity of u c enters the enclosure from the top right corner and exits from the bottom right corner. The vertical wall of the left side is subjected to a hot and constant temperature T h . Also, other walls are insulated. It is found that the heat transfer is increased via increasing the Hartmann and Reynolds numbers. For low Reynolds numbers, the enhances of the Hartman number leads to a slightly increases of the average Nusselt number, but for high Reynolds numbers, the average Nusselt number gets an ascending trend and the increase in the Hartmann number shows its effect more pronounced. Also, with increase in Ri, the effect of nanofluid on the heat transfer increases. Due to practical impotence, the study of mixed convection heat transfer in enclosures and various shaped of cavities has attracted remarkable attentions in the past few decades. Significant applications of the mixed convection flow can be found in atmospheric flows, solar energy storage, heat exchangers, lubrication technology, drying technologies, cooling of the electronic devices, etc. The present results are original and new for the problem of MHD mixed convection flow and heat transfer in an open C-shaped enclosure using water-copper oxide nanofluid. Comparison of the obtained results with those from the open literature (Mahmoodi et al. [24]) is acceptable.

Experience with advanced instrumentation in a hot section cascade

NASA Technical Reports Server (NTRS)

Yeh, Frederick C.; Gladden, Herbert J.

1989-01-01

The Lewis Research Center gas turbine Hot Section Test Facility was developed to provide a real engine environment with known boundary conditions for the aerothermal performance evaluation and verification of computer design codes. This verification process requires experimental measurements in a hostile environment. The research instruments used in this facility are presented, and their characteristics and how they perform in this environment are discussed. The research instrumentation consisted of conventional pressure and temperature sensors, as well as thin-film thermocouples and heat flux gages. The hot gas temperature was measured by an aspirated temperature probe and by a dual-element, fast-response temperature probe. The data acquisition mode was both steady state and time dependent. These experiments were conducted over a wide range of gas Reynolds numbers, exit gas Mach numbers, and heat flux levels. This facility was capable of testing at temperatures up to 1600 K, and at pressures up to 18 atm. These corresponded to an airfoil exit Reynolds number range of 0.5 x 10(6) to 2.5 x 10(6) based on the airfoil chord of 5.55 cm. The results characterize the performance capability and the durability of the instrumentation. The challenge of making measurements in hostile environments is also discussed. The instruments exhibited more than adequate durability to achieve the measurement profile. About 70 percent of the thin-film thermocouples and the dual-element temperature probe survived several hundred thermal cycles and more than 35 hr at gas temperatures up to 1600 K. Within the experimental uncertainty, the steady-state and transient heat flux measurements were comparable and consistent over the range of Reynolds numbers tested.

Experience with advanced instrumentation in a hot section cascade

NASA Astrophysics Data System (ADS)

Yeh, Frederick C.; Gladden, Herbert J.

The Lewis Research Center gas turbine Hot Section Test Facility was developed to provide a real engine environment with known boundary conditions for the aerothermal performance evaluation and verification of computer design codes. This verification process requires experimental measurements in a hostile environment. The research instruments used in this facility are presented, and their characteristics and how they perform in this environment are discussed. The research instrumentation consisted of conventional pressure and temperature sensors, as well as thin-film thermocouples and heat flux gages. The hot gas temperature was measured by an aspirated temperature probe and by a dual-element, fast-response temperature probe. The data acquisition mode was both steady state and time dependent. These experiments were conducted over a wide range of gas Reynolds numbers, exit gas Mach numbers, and heat flux levels. This facility was capable of testing at temperatures up to 1600 K, and at pressures up to 18 atm. These corresponded to an airfoil exit Reynolds number range of 0.5 x 10(6) to 2.5 x 10(6) based on the airfoil chord of 5.55 cm. The results characterize the performance capability and the durability of the instrumentation. The challenge of making measurements in hostile environments is also discussed. The instruments exhibited more than adequate durability to achieve the measurement profile. About 70 percent of the thin-film thermocouples and the dual-element temperature probe survived several hundred thermal cycles and more than 35 hr at gas temperatures up to 1600 K. Within the experimental uncertainty, the steady-state and transient heat flux measurements were comparable and consistent over the range of Reynolds numbers tested.

Collaborative Behaviors Practiced by Teachers and Their Administrators Resulting in Increased California High School Exit Exam Pass Rates for Students with Learning Disabilities

ERIC Educational Resources Information Center

Everett, Katherine E.

2013-01-01

Purpose. The purpose of this replication study was to describe the extent to which seven collaborative behaviors were demonstrated by general education teachers assigned students with disabilities, education specialists, and their administrators in selected California high schools that exceeded the state average pass rate for 10th-grade students…

Coupled-Flow Simulation of HP-LP Turbines Has Resulted in Significant Fuel Savings

NASA Technical Reports Server (NTRS)

Veres, Joseph P.

2001-01-01

Our objective was to create a high-fidelity Navier-Stokes computer simulation of the flow through the turbines of a modern high-bypass-ratio turbofan engine. The simulation would have to capture the aerodynamic interactions between closely coupled high- and low-pressure turbines. A computer simulation of the flow in the GE90 turbofan engine's high-pressure (HP) and low-pressure (LP) turbines was created at GE Aircraft Engines under contract with the NASA Glenn Research Center. The three-dimensional steady-state computer simulation was performed using Glenn's average-passage approach named APNASA. The areas upstream and downstream of each blade row mutually interact with each other during engine operation. The embedded blade row operating conditions are modeled since the average passage equations in APNASA actively include the effects of the adjacent blade rows. The turbine airfoils, platforms, and casing are actively cooled by compressor bleed air. Hot gas leaks around the tips of rotors through labyrinth seals. The flow exiting the high work HP turbines is partially transonic and, therefore, has a strong shock system in the transition region. The simulation was done using 121 processors of a Silicon Graphics Origin 2000 (NAS 02K) cluster at the NASA Ames Research Center, with a parallel efficiency of 87 percent in 15 hr. The typical average-passage analysis mesh size per blade row was 280 by 45 by 55, or approx.700,000 grid points. The total number of blade rows was 18 for a combined HP and LP turbine system including the struts in the transition duct and exit guide vane, which contain 12.6 million grid points. Design cycle turnaround time requirements ran typically from 24 to 48 hr of wall clock time. The number of iterations for convergence was 10,000 at 8.03x10(exp -5) sec/iteration/grid point (NAS O2K). Parallel processing by up to 40 processors is required to meet the design cycle time constraints. This is the first-ever flow simulation of an HP and LP turbine. In addition, it includes the struts in the transition duct and exit guide vanes.

High Temperature Water Heat Pipes Radiator for a Brayton Space Reactor Power System

NASA Astrophysics Data System (ADS)

El-Genk, Mohamed S.; Tournier, Jean-Michel

2006-01-01

A high temperature water heat pipes radiator design is developed for a space power system with a sectored gas-cooled reactor and three Closed Brayton Cycle (CBC) engines, for avoidance of single point failures in reactor cooling and energy conversion and rejection. The CBC engines operate at turbine inlet and exit temperatures of 1144 K and 952 K. They have a net efficiency of 19.4% and each provides 30.5 kWe of net electrical power to the load. A He-Xe gas mixture serves as the turbine working fluid and cools the reactor core, entering at 904 K and exiting at 1149 K. Each CBC loop is coupled to a reactor sector, which is neutronically and thermally coupled, but hydraulically decoupled to the other two sectors, and to a NaK-78 secondary loop with two water heat pipes radiator panels. The segmented panels each consist of a forward fixed segment and two rear deployable segments, operating hydraulically in parallel. The deployed radiator has an effective surface area of 203 m2, and when the rear segments are folded, the stowed power system fits in the launch bay of the DELTA-IV Heavy launch vehicle. For enhanced reliability, the water heat pipes operate below 50% of their wicking limit; the sonic limit is not a concern because of the water, high vapor pressure at the temperatures of interest (384 - 491 K). The rejected power by the radiator peaks when the ratio of the lengths of evaporator sections of the longest and shortest heat pipes is the same as that of the major and minor widths of the segments. The shortest and hottest heat pipes in the rear segments operate at 491 K and 2.24 MPa, and each rejects 154 W. The longest heat pipes operate cooler (427 K and 0.52 MPa) and because they are 69% longer, reject more power (200 W each). The longest and hottest heat pipes in the forward segments reject the largest power (320 W each) while operating at ~ 46% of capillary limit. The vapor temperature and pressure in these heat pipes are 485 K and 1.97 MPa. By contrast, the shortest water heat pipes in the forward segments operate much cooler (427 K and 0.52 MPa), and reject a much lower power of 45 W each. The radiator with six fixed and 12 rear deployable segments rejects a total of 324 kWth, weights 994 kg and has an average specific power of 326 Wth/kg and a specific mass of 5.88 kg/m2.

Evaluation of catalytic combustion of actual coal-derived gas

NASA Technical Reports Server (NTRS)

Blanton, J. C.; Shisler, R. A.

1982-01-01

The combustion characteristics of a Pt-Pl catalytic reactor burning coal-derived, low-Btu gas were investigated. A large matrix of test conditions was explored involving variations in fuel/air inlet temperature and velocity, reactor pressure, and combustor exit temperature. Other data recorded included fuel gas composition, reactor temperatures, and exhaust emissions. Operating experience with the reactor was satisfactory. Combustion efficiencies were quite high (over 95 percent) over most of the operating range. Emissions of NOx were quite high (up to 500 ppm V and greater), owing to the high ammonia content of the fuel gas.

Plasma Potential and Langmuir Probe Measurements in the Near-field Plume of the NASA 300M Hall Thruster

NASA Technical Reports Server (NTRS)

Herman, Daniel A; Shastry, Rohit; Huang, Wensheng; Soulas, George C.; KamHawi, Hani

2012-01-01

In order to aid in the design of high-power Hall thrusters and provide experimental validation for existing modeling efforts, plasma potential and Langmuir probe measurements were performed in the near-field plume of the NASA 300M Hall thruster. A probe array consisting of a Faraday probe, Langmuir probe, and emissive probe was used to interrogate the plume from approximately 0.1 - 2.0 DT,m downstream of the thruster exit plane at four operating conditions: 300 V, 400 V, and 500 V at 20 kW as well as 300 V at 10 kW. Results show that the acceleration zone and high-temperature region were contained within 0.3 DT,m from the exit plane at all operating conditions. Isothermal lines were shown to strongly follow magnetic field lines in the nearfield, with maximum temperatures ranging from 19 - 27 eV. The electron temperature spatial distribution created large drops in measured floating potentials in front of the magnetic pole surfaces where the plasma density was small, which suggests strong sheaths at these surfaces. The data taken have provided valuable information for future design and modeling validation, and complements ongoing internal measurement efforts on the NASA 300 M.

Multiphysics Modeling of a Single Channel in a Nuclear Thermal Propulsion Grooved Ring Fuel Element

NASA Technical Reports Server (NTRS)

Kim, Tony; Emrich, William J., Jr.; Barkett, Laura A.; Mathias, Adam D.; Cassibry, Jason T.

2013-01-01

In the past, fuel rods have been used in nuclear propulsion applications. A new fuel element concept that reduces weight and increases efficiency uses a stack of grooved discs. Each fuel element is a flat disc with a hole on the interior and grooves across the top. Many grooved ring fuel elements for use in nuclear thermal propulsion systems have been modeled, and a single flow channel for each design has been analyzed. For increased efficiency, a fuel element with a higher surface-area-to-volume ratio is ideal. When grooves are shallower, i.e., they have a lower surface area, the results show that the exit temperature is higher. By coupling the physics of turbulence with those of heat transfer, the effects on the cooler gas flowing through the grooves of the thermally excited solid can be predicted. Parametric studies were done to show how a pressure drop across the axial length of the channels will affect the exit temperatures of the gas. Geometric optimization was done to show the behaviors that result from the manipulation of various parameters. Temperature profiles of the solid and gas showed that more structural optimization is needed to produce the desired results. Keywords: Nuclear Thermal Propulsion, Fuel Element, Heat Transfer, Computational Fluid Dynamics, Coupled Physics Computations, Finite Element Analysis

Trajectory, Development, and Temperature of Spark Kernels Exiting into Quiescent Air (Preprint)

DTIC Science & Technology

2012-04-01

spark is an electrical discharge in which a portion of the energy is transferred to plasma and the surrounding fluid and the remaining portion is lost...integrated radiation intensity, λα λ λ λλλ dII ∫=∆ 2 1 . (1) αλ is the spectral absorption coefficient which accounts for variations...premixed hydrogen flame anchored to a Hencken burner. This flame has been well characterized by CARS measurements26,27. A temperature profile26 was assumed

Heat exchanger with ceramic elements

DOEpatents

Corey, John A.

1986-01-01

An annular heat exchanger assembly includes a plurality of low thermal growth ceramic heat exchange members with inlet and exit flow ports on distinct faces. A mounting member locates each ceramic member in a near-annular array and seals the flow ports on the distinct faces into the separate flow paths of the heat exchanger. The mounting member adjusts for the temperature gradient in the assembly and the different coefficients of thermal expansion of the members of the assembly during all operating temperatures.

Design, Construction, and Validation of the AFIT Small Scale Combustion Facility and Sectional Model of the Ultra-Compact Combustor

DTIC Science & Technology

2007-03-01

use. At the end of these lines, two high temperature hoses provide flexibility for connection. 57 Figure 28: Heater emergency shutoff...stainless steel braided , Teflon tubing. This enables the probe to be easily positioned as required. The oil temperature is measured by a K-type...used to cool emissions probe. The sample gases exit the probe into a 1/4” piece of braided , flexible Teflon tubing to provide for probe

Simple Forest Canopy Thermal Exitance Model

NASA Technical Reports Server (NTRS)

Smith J. A.; Goltz, S. M.

1999-01-01

We describe a model to calculate brightness temperature and surface energy balance for a forest canopy system. The model is an extension of an earlier vegetation only model by inclusion of a simple soil layer. The root mean square error in brightness temperature for a dense forest canopy was 2.5 C. Surface energy balance predictions were also in good agreement. The corresponding root mean square errors for net radiation, latent, and sensible heat were 38.9, 30.7, and 41.4 W/sq m respectively.

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

Process for synthesis of beryllium chloride dietherate

DOEpatents

Bergeron, Charles; Bullard, John E.; Morgan, Evan

1991-01-01

A low temperature method of producing beryllium chloride dietherate through the addition of hydrogen chloride gas to a mixture of beryllium metal in ether in a reaction vessel is described. A reflux condenser provides an exit for hydrogen produced form the reaction. A distillation condenser later replaces the reflux condenser for purifying the resultant product.

In-stream measurements of combustion during Mach 5 to 7 tests of the Hypersonic Research Engine (HRE)

NASA Technical Reports Server (NTRS)

Lezberg, Erwin A.; Metzler, Allen J.; Pack, William D.

1993-01-01

Results of in-stream combustion measurements taken during Mach 5 to 7 true simulation testing of the Hypersonic Research Engine/Aerothermodynamic Integration Model (HRE/AIM) are presented. These results, the instrumentation techniques, and configuration changes to the engine installation that were required to test this model are described. In test runs at facility Mach numbers of 5 to 7, an exhaust instrumentation ring which formed an extension of the engine exhaust nozzle shroud provided diagnostic measurements at 10 circumferential locations in the HRE combustor exit plane. The measurements included static and pitot pressures using conventional conical probes, combustion gas temperatures from cooled-gas pyrometer probes, and species concentration from analysis of combustion gas samples. Results showed considerable circumferential variation, indicating that efficiency losses were due to nonuniform fuel distribution or incomplete mixing. Results using the Mach 7 facility nozzle but with Mach 6 temperature simulation, 1590 to 1670 K, showed indications of incomplete combustion. Nitric oxide measurements at the combustor exit peaked at 2000 ppmv for stoichiometric combustion at Mach 6.

Heat Transfer on a Film-Cooled Blade - Effect of Hole Physics

NASA Technical Reports Server (NTRS)

Garg, Vijay K.; Rigby, David L.

1998-01-01

A multi-block, three-dimensional Navier-Stokes code has been used to study the within-hole and near-hole physics in relation to heat transfer on a film-cooled blade. The flow domain consists of the coolant flow through the plenum and hole-pipes for the three staggered rows of shower-head holes on the VK1 rotor, and the main flow over the blade. A multi-block grid is generated that is nearly orthogonal to the various surfaces. It may be noted that for the VK1 rotor the shower-head holes are inclined at 30 deg. to the spanwise direction, and are normal to the streamwise direction on the blade. Wilcox's k-omega turbulence model is used. The present study provides a much better comparison for the heat transfer coefficient at the blade mid-span with the experimental data than an earlier analysis wherein coolant velocity and temperature distributions were specified at the hole exits rather than extending the computational domain into the hole-pipe and plenum. Details of the distributions of coolant velocity, temperature, k and omega at the hole exits are also presented.

Numerical analysis of conjugate heat transfer due to oblique impingement of turbulent slot jet onto a flat plate

NASA Astrophysics Data System (ADS)

Shashikant, Patel, Devendra Kumar; Kumar, Jayesh; Kumar, Vishwajeet

2018-04-01

The conjugate heat transfer due to oblique impingement of two-dimensional, steady state, incompressible, turbulent slot jet on a uniformly heated flat plate has been studied in the present work. The standard high Reynolds number two-equation k - ɛ eddy viscosity model has been used for numerical simulation. The Reynolds number based on the hydraulic diameter of nozzle exit and turbulent intensity maintained at 9, 900 and 2% respectively. The angle of inclination 30°, 45°, 60° and, 75° degrees are considered for the numerical study. A uniform temperature higher than the jet exit temperature is provided to the bottom surface of the plate. The flow field have been studied using the contour plots of pressure and velocity in the fluid domain. The influence of inclination on the distribution of the local Nusselt number over the surface of impingement have been presented. It is found that the angle of impingement influences the flow field and heat transfer characteristics more in the downhill direction of the stagnation zone compared to the uphill direction.

Effect of segmented electrode length on the performances of Hall thruster

NASA Astrophysics Data System (ADS)

Duan, Ping; Chen, Long; Liu, Guangrui; Bian, Xingyu; Yin, Yan

2016-09-01

The influences of the low-emissive graphite segmented electrode placed near the channel exit on the discharge characteristics of Hall thruster are studied using the particle-in-cell method. A two-dimensional physical model is established according to the Hall thruster discharge channel configuration. The effects of electrode length on potential, ion density, electron temperature, ionization rate and discharge current are investigated. It is found that, with the increasing of segmented electrode length, the equipotential lines bend towards the channel exit, and approximately parallel to the wall at the channel surface, radial velocity and radial flow of ions are increased, and the electron temperature is also enhanced. Due to the conductive characteristic of electrodes, the radial electric field and the axial electron conductivity near the wall are enhanced, and the probability of the electron-atom ionization is reduced, which leads to the degradation of ionization rate in discharge channel. However, the interaction between electrons and the wall enhances the near wall conductivity, therefore the discharge current grows along with the segmented electrode length, and the performance of the thruster is also affected.

Film Cooling Flow Effects on Post-Combustor Trace Chemistry

NASA Technical Reports Server (NTRS)

Wey, Thomas; Liu, Nan-Suey

2003-01-01

Film cooling injection is widely applied in the thermal design of turbomachinery, as it contributes to achieve higher operating temperature conditions of modern gas turbines, and to meet the requirements for reliability and life cycles. It is a significant part of the high-pressure turbine system. The film cooling injection, however, interacts with the main flow and is susceptible to have an influence on the aerodynamic performance of the cooled components, and through that may cause a penalty on the overall efficiency of the gas turbine. The main reasons are the loss of total pressure resulting from mixing the cooling air with mainstream and the reduction of the gas stagnation temperature at the exit of the combustion chamber to a lower value at the exit of nozzle guide vane. In addition, the impact of the injected air on the evolution of the trace species of the hot gas is not yet quite clear. This work computationally investigates the film cooling influence on post-combustor trace chemistry, as trace species in aircraft exhaust affect climate and ozone.

Unsteady specific work and isentropic efficiency of a radial turbine driven by pulsed detonations

NASA Astrophysics Data System (ADS)

Rouser, Kurt P.

There has been longstanding government and industry interest in pressure-gain combustion for use in Brayton cycle based engines. Theoretically, pressure-gain combustion allows heat addition with reduced entropy loss. The pulsed detonation combustor (PDC) is a device that can provide such pressure-gain combustion and possibly replace typical steady deflagration combustors. The PDC is inherently unsteady, however, and comparisons with conventional steady deflagration combustors must be based upon time-integrated performance variables. In this study, the radial turbine of a Garrett automotive turbocharger was coupled directly to and driven, full admission, by a PDC in experiments fueled by hydrogen or ethylene. Data included pulsed cycle time histories of turbine inlet and exit temperature, pressure, velocity, mass flow, and enthalpy. The unsteady inlet flowfield showed momentary reverse flow, and thus unsteady accumulation and expulsion of mass and enthalpy within the device. The coupled turbine-driven compressor provided a time-resolved measure of turbine power. Peak power increased with PDC fill fraction, and duty cycle increased with PDC frequency. Cycle-averaged unsteady specific work increased with fill fraction and frequency. An unsteady turbine efficiency formulation is proposed, including heat transfer effects, enthalpy flux-weighted total pressure ratio, and ensemble averaging over multiple cycles. Turbine efficiency increased with frequency but was lower than the manufacturer reported conventional steady turbine efficiency.

Thermodynamic efficiency analysis and cycle optimization of deeply precooled combined cycle engine in the air-breathing mode

NASA Astrophysics Data System (ADS)

Zhang, Jianqiang; Wang, Zhenguo; Li, Qinglian

2017-09-01

The efficiency calculation and cycle optimization were carried out for the Synergistic Air-Breathing Rocket Engine (SABRE) with deeply precooled combined cycle. A component-level model was developed for the engine, and exergy efficiency analysis based on the model was carried out. The methods to improve cycle efficiency have been proposed. The results indicate cycle efficiency of SABRE is between 29.7% and 41.7% along the flight trajectory, and most of the wasted exergy is occupied by the unburned hydrogen in exit gas. Exergy loss exists in each engine component, and the sum losses of main combustion chamber(CC), pre-burner(PB), precooler(PC) and 3# heat exchanger(HX3) are greater than 71.3% of the total loss. Equivalence ratio is the main influencing factor of cycle, and it can be regulated by adjusting parameters of helium loop. Increase the maximum helium outlet temperature of PC by 50 K, the total assumption of hydrogen will be saved by 4.8%, and the cycle efficiency is advanced by 3% averagely in the trajectory. Helium recirculation scheme introduces a helium recirculation loop to increase local helium flow rate of PC. It turns out the total assumption of hydrogen will be saved by 9%, that's about 1740 kg, and the cycle efficiency is advanced by 5.6% averagely.

Flow boiling with enhancement devices for cold plate coolant channel design

NASA Technical Reports Server (NTRS)

Boyd, Ronald D., Sr.; Smith, Alvin

1990-01-01

The use of flow boiling for thermal energy transport is intended to provide an alternative for accommodating higher heat fluxes in commercial space systems. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls, spiral fins, or both spiral fins and a twisted tape; (2) examine the effects of channel diameter and subcooling; and (3) develop an improved reduction analysis and/or suggest possible heat transfer correlation of the present data. Freon-11 is the working fluid. Two-dimensional (circumferential and axial) wall temperature distributions were measured for coolant channels with the above noted internal geometries. The flow regimes which are being studied are: (1) single phase; (2) subcooled flow boiling; and (3) stratified flow boiling. The inside diameter of all test sections is near 1.0 cm. Cicumferentially averaged heat transfer coefficients at several axial locations were obtained for selected coolant channels for a mass velocity of 210 kg/sq m s, an exit pressure of 0.19 MPa (absolute), and an inlet subcooling of 20.8 C. Overall (averaged over the entire channel) heat transfer coefficients were compared for the above channel geometries. This comparison showed that the channel with large pitch spiral fins had higher heat transfer coefficients at all power levels.

Microbiologic progression of post-traumatic peritonitis.

PubMed

Nyström, P O; Skau, T; Johansson, L; Lennquist, S

1985-08-01

The natural course of post-traumatic peritonitis was studied in 17 pigs. Following a standardized missile wound to the abdomen the pigs were operated on and observed in continuous anesthesia for periods up to 3 days. Bacterial density was measured in peritoneal exudate, parietal peritoneum, laparotomy wound, and projectile entrance and exit wounds at this operation and also at relaparotomy, which terminated the experiments. The bacterial density showed significant perioperative fall, averaging X 1,905 in peritoneal exudate and X 40 in parietal peritoneum. From a low postoperative level (mean c. 10(2)/ml or /gm), bacterial density increased significantly in the observation period. In peritoneal exudate the increase was X 4,073 and in peritoneum X 2,630. In laparotomy and projectile entrance and exit wounds the corresponding figures were X 234, X 126, and X 15. The bacterial population's perioperative reduction and subsequent proliferation were interpreted as reflecting the host defense, which accordingly was limited in capacity and duration.

Computation of Three-Dimensional Compressible Flow From a Rectangular Nozzle with Delta Tabs

NASA Technical Reports Server (NTRS)

Reddy, D. R.; Steffen, C. J., Jr.; Zaman, K. B. M. Q.

1999-01-01

A three-dimensional viscous flow analysis is performed using a time-marching Reynolds-averaged Navier-Stokes code for a 3:1 rectangular nozzle with two delta tabs located at the nozz1e exit plane to enhance mixing. Two flow configurations, a subsonic jet case and a supersonic jet case using the same rate configuration, which were previously studied experimentally, are computed and compared with the experimental data. The experimental data include streamwise velocity and vorticity distributions for the subsonic case, and Mach number distributions for the supersonic case, at various axial locations downstream of the nozzle exit. The computational results show very good agreement with the experimental data. In addition, the effect of compressibility on vorticity dynamics is examined by comparing the vorticity contours of the subsonic jet case with those of the supersonic jet case which were not measured in the experiment.

Multiphase Model of Semisolid Slurry Generation and Isothermal Holding During Cooling Slope Rheoprocessing of A356 Al Alloy

NASA Astrophysics Data System (ADS)

Das, Prosenjit; Samanta, Sudip K.; Mondal, Biswanath; Dutta, Pradip

2018-04-01

In the present paper, we present an experimentally validated 3D multiphase and multiscale solidification model to understand the transport processes involved during slurry generation with a cooling slope. In this process, superheated liquid alloy is poured at the top of the cooling slope and allowed to flow along the slope under the influence of gravity. As the melt flows down the slope, it progressively loses its superheat, starts solidifying at the melt/slope interface with formation of solid crystals, and eventually exits the slope as semisolid slurry. In the present simulation, the three phases considered are the parent melt as the primary phase, and the solid grains and air as secondary phases. The air phase forms a definable air/liquid melt interface as the free surface. After exiting the slope, the slurry fills an isothermal holding bath maintained at the slope exit temperature, which promotes further globularization of microstructure. The outcomes of the present model include prediction of volume fractions of the three different phases considered, grain evolution, grain growth, size, sphericity and distribution of solid grains, temperature field, velocity field, macrosegregation and microsegregation. In addition, the model is found to be capable of making predictions of morphological evolution of primary grains at the onset of isothermal coarsening. The results obtained from the present simulations are validated by performing quantitative image analysis of micrographs of the rapidly oil-quenched semisolid slurry samples, collected from strategic locations along the slope and from the isothermal slurry holding bath.

Preliminary Design of Critical Function Monitoring System of PGSFR

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-07-01

A PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor) is under development at Korea Atomic Energy Research Institute. A critical function monitoring system of the PGSFR is preliminarily studied. The functions of CFMS are to display critical plant variables related to the safety of the plant during normal and accident conditions and guide the operators corrective actions to keep the plant in a safe condition and mitigate the consequences of accidents. The minimal critical functions of the PGSFR are composed of reactivity control, reactor core cooling, reactor coolant system integrity, primary heat transfer system(PHTS) heat removal, sodium water reaction mitigation, radiation controlmore » and containment conditions. The variables and alarm legs of each critical function of the PGSFR are as follows; - Reactivity control: The variables of reactivity control function are power range neutron flux instrumentation, intermediate range neutron flux instrumentation, source range neutron flux instrumentation, and control rod bottom contacts. The alarm leg to display the reactivity controls consists of status of control drop malfunction, high post trip power and thermal reactivity addition. - Reactor core cooling: The variables are PHTS sodium level, hot pool temperature of PHTS, subassembly exit temperature, cold pool temperature of the PHTS, PHTS pump current, and PHTS pump breaker status. The alarm leg consists of high core delta temperature, low sodium level of the PHTS, high subassembly exit temperature, and low PHTS pump load. - Reactor coolant system integrity: The variables are PHTS sodium level, cover gas pressure, and safeguard vessel sodium level. The alarm leg is composed of low sodium level of PHTS, high cover gas pressure and high sodium level of the safety guard vessel. - PHTS heat removal: The variables are PHTS sodium level, hot pool temperature of PHTS, core exit temperature, cold pool temperature of the PHTS, flow rate of passive residual heat removal system, flow rate of active residual heat removal system, and temperatures of air heat exchanger temperature of residual heat removal systems. The alarm legs are composed of two legs of a 'passive residual heat removal system not cooling' and 'active residual heat removal system not cooling'. - Sodium water reaction mitigation: The variables are intermediate heat transfer system(IHTS) pressure, pressure and temperature and level of sodium dump tank, the status of rupture disk, hydrogen concentration in IHTS and direct variable of sodium-water-reaction measure. The alarm leg consists of high IHTS pressure, the status of sodium water reaction mitigation system and the indication of direct measure. - Radiation control: The variables are radiation of PHTS, radiation of IHTS, and radiation of containment purge. The alarm leg is composed of high radiation of PHTS and IHTS, and containment purge system. - Containment condition: The variables are containment pressure, containment isolation status, and sodium fire. The alarm leg consists of high containment pressure, status of containment isolation and status of sodium fire. (authors)« less

Radiation dose uncertainty and correction for a mouse orthotopic and xenograft irradiation model.

PubMed

Gan, Gregory N; Altunbas, Cem; Morton, John J; Eagles, Justin; Backus, Jennifer; Dzingle, Wayne; Raben, David; Jimeno, Antonio

2016-01-01

In animal irradiation models, reported dose can vary significantly from the actual doses delivered. We describe an effective method for in vivo dose verification. Mice bearing commercially-available cell line or patient-derived tumor cell orthotopic or flank xenografts were irradiated using a 160 kVp, 25 mA X-ray source. Entrance dose was evaluated using optically-stimulated luminescence dosimeters (OSLD) and exit dose was assessed using radiochromic film dosimetry. Tumor position within the irradiation field was validated using external fiducial markers. The average entrance dose in orthotopic tumors from 10 OSLDs placed on two different animal irradiation days was 514 ± 37 cGy (range: 437-545). Exit dose measurements taken from seven radiochromic films on two separate days were 341 ± 21 cGy (a 34% attenuation). Flank tumor irradiation doses measured by OSLD were 368 ± 9 cGy compared to exit doses of 330 cGy measured by radiochromic film. Variations related to the irradiation model can lead to significant under or overdosing in vivo which can affect tumor control and/or biologic endpoints that are dose-dependent. We recommend that dose measurements be determined empirically based on the mouse model and irradiator used and dose compensation adjustments performed to ensure correct and appropriate doses.

Orbital thermal analysis of lattice structured spacecraft using color video display techniques

NASA Technical Reports Server (NTRS)

Wright, R. L.; Deryder, D. D.; Palmer, M. T.

1983-01-01

A color video display technique is demonstrated as a tool for rapid determination of thermal problems during the preliminary design of complex space systems. A thermal analysis is presented for the lattice-structured Earth Observation Satellite (EOS) spacecraft at 32 points in a baseline non Sun-synchronous (60 deg inclination) orbit. Large temperature variations (on the order of 150 K) were observed on the majority of the members. A gradual decrease in temperature was observed as the spacecraft traversed the Earth's shadow, followed by a sudden rise in temperature (100 K) as the spacecraft exited the shadow. Heating rate and temperature histories of selected members and color graphic displays of temperatures on the spacecraft are presented.

NASA low-speed centrifugal compressor for fundamental research

NASA Technical Reports Server (NTRS)

Wood, J. R.; Adam, P. W.; Buggele, A. E.

1983-01-01

A new centrifugal compressor facility being built by the NASA Lewis Research Center is described; its purpose is to obtain 'benchmark' experimental data for internal flow code verification and modeling. The facility will be heavily instrumented with standard pressure and temperature probes and have provisions for flow visualization and laser Doppler velocimetry. The facility will accommodate rotational speeds to 2400 rpm and will be rated at pressures to 1.25 atm. The initial compressor stage for testing is geometrically and dynamically representative of modern high-performance stages with the exception of Mach number levels. Design exit tip speed for the initial stage is 500 ft/sec with a pressure ratio of 1.17. The rotor exit backsweep is 55 deg from radial. The facility is expected to be operational in the first half of 1985.

Performance of an asymmetric short annular diffuser with a nondiverging inner wall using suction. [control of radial profiles of diffuser exit velocity

NASA Technical Reports Server (NTRS)

Juhasz, A.

1974-01-01

The performance of a short highly asymmetric annular diffuser equipped with wall bleed (suction) capability was evaluated at nominal inlet Mach numbers of 0.188, 0.264, and 0.324 with the inlet pressure and temperature at near ambient values. The diffuser had an area ratio of 2.75 and a length- to inlet-height ratio of 1.6. Results show that the radial profiles of diffuser exit velocity could be controlled from a severely hub peaked to a slightly tip biased form by selective use of bleed. At the same time, other performance parameters were also improved. These results indicate the possible application of the diffuser bleed technique to control flow profiles to gas turbine combustors.

Characteristics and mechanism of laser-induced surface damage initiated by metal contaminants

NASA Astrophysics Data System (ADS)

Shi, Shuang; Sun, Mingying; Shi, Shuaixu; Li, Zhaoyan; Zhang, Ya-nan; Liu, Zhigang

2015-08-01

In high power laser facility, contaminants on optics surfaces reduce damage resistance of optical elements and then decrease their lifetime. By damage test experiments, laser damage induced by typical metal particles such as stainless steel 304 is studied. Optics samples with metal particles of different sizes on surfaces are prepared artificially based on the file and sieve. Damage test is implemented in air using a 1-on-1 mode. Results show that damage morphology and mechanism caused by particulate contamination on the incident and exit surfaces are quite different. Contaminants on the incident surface absorb laser energy and generate high temperature plasma during laser irradiation which can ablate optical surface. Metal particles melt and then the molten nano-particles redeposit around the initial particles. Central region of the damaged area bears the same outline as the initial particle because of the shielding effect. However, particles on the exit surface absorb a mass of energy, generate plasma and splash lots of smaller particles, only a few of them redeposit at the particle coverage area on the exit surface. Most of the laser energy is deposited at the interface of the metal particle and the sample surface, and thus damage size on the exit surface is larger than that on the incident surface. The areas covered by the metal particle are strongly damaged. And the damage sites are more serious than that on the incident surface. Besides damage phenomenon also depends on coating and substrate materials.

Approximate similarity principle for a full-scale STOVL ejector

NASA Astrophysics Data System (ADS)

Barankiewicz, Wendy S.; Perusek, Gail P.; Ibrahim, Mounir B.

1994-03-01

Full-scale ejector experiments are expensive and difficult to implement at engine exhaust temperatures. For this reason the utility of using similarity principles, in particular the Munk and prim principle for isentropic flow, was explored. Static performance test data for a full-scale thrust augmenting ejector were analyzed for primary flow temperature up to 1560 R. At different primary temperatures, exit pressure contours were compared for similarity. A nondimensional flow parameter is then used to eliminate primary nozzle temperature dependence and verify similarity between the hot and cold flow experiments. Under the assumption that an appropriate similarity principle can be established, properly chosen performance parameters were found to be similar for both flow and cold flow model tests.

Aerodynamic laser-heated contactless furnace for neutron scattering experiments at elevated temperatures

NASA Astrophysics Data System (ADS)

Landron, Claude; Hennet, Louis; Coutures, Jean-Pierre; Jenkins, Tudor; Alétru, Chantal; Greaves, Neville; Soper, Alan; Derbyshire, Gareth

2000-04-01

Conventional radiative furnaces require sample containment that encourages contamination at elevated temperatures and generally need windows which restrict the entrance and exit solid angles required for diffraction and scattering measurements. We describe a contactless windowless furnace based on aerodynamic levitation and laser heating which has been designed for high temperature neutron scattering experiments. Data from initial experiments are reported for crystalline and amorphous oxides at temperatures up to 1900 °C, using the spallation neutron source ISIS together with our laser-heated aerodynamic levitator. Accurate reproduction of thermal expansion coefficients and radial distribution functions have been obtained, demonstrating the utility of aerodynamic levitation methods for neutron scattering methods.

High Temperature Ceramic Guide Vane Temperature and Pressure Distribution Calculation for Flow with Cooling Jets

NASA Technical Reports Server (NTRS)

Srivastava, Rakesh

2004-01-01

A ceramic guide vane has been designed and tested for operation under high temperature. Previous efforts have suggested that some cooling flow may be required to alleviate the high temperatures observed near the trailing edge region. The present report describes briefly a three-dimensional viscous analysis carried out to calculate the temperature and pressure distribution on the blade surface and in the flow path with a jet of cooling air exiting from the suction surface near the trailing edge region. The data for analysis was obtained from Dr. Craig Robinson. The surface temperature and pressure distribution along with a flowfield distribution is shown in the results. The surface distribution is also given in a tabular form at the end of the document.

Free compressible jet investigation

NASA Astrophysics Data System (ADS)

De Gregorio, Fabrizio

2014-03-01

The nozzle pressure ratio (NPR) effect on a supersonic turbulent jet was investigated. A dedicated convergent/divergent nozzle together with a flow feeding system was designed and manufactured. A nozzle Mach exit of M j = 1.5 was selected in order to obtain a convective Mach number of M c = 0.6. The flow was investigated for over-expanded, correctly expanded and under-expanded jet conditions. Mach number, total temperature and flow velocity measurements were carried out in order to characterise the jet behaviour. The inlet conditions of the jet flow were monitored in order to calculate the nozzle exit speed of sound and evaluate the mean Mach number distribution starting from the flow velocity data. A detailed analysis of the Mach results obtained by a static Pitot probe and by a particle image velocimetry measurement system was carried out. The mean flow velocity was investigated, and the axial Mach decay and the spreading rate were associated with the flow structures and with the compressibility effects. Aerodynamics of the different jet conditions was evaluated, and the shock cells structures were detected and discussed correlating the jet structure to the flow fluctuation and local turbulence. The longitudinal and radial distribution of the total temperature was investigated, and the temperature profiles were analysed and discussed. The total temperature behaviour was correlated to the turbulent phenomena and to the NPR jet conditions. Self-similarity condition was encountered and discussed for the over-expanded jet. Compressibility effects on the local turbulence, on the turbulent kinetic energy and on the Reynolds tensor were discussed.

Effect of Environment on the Stress- Rupture Behavior of a C/SiC Composite Studied

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Kiser, J. Douglas; Opila, Elizabeth J.; Calomino, Anthony M.

2002-01-01

Advanced reusable launch vehicles will likely incorporate fiber-reinforced ceramic matrix composites (CMC's) in critical propulsion and airframe components. The use of CMC's is highly desirable to save weight, improve reuse capability, and increase performance. One of the candidate CMC materials is carbon-fiber-reinforced silicon carbide (C/SiC). In potential propulsion applications, such as turbopump rotors and nozzle exit ramps, C/SiC components will be subjected to a service cycle that includes mechanical loading under complex, high-pressure environments containing hydrogen, oxygen, and steam. Degradation of both the C fibers and the SiC matrix are possible in these environments. The objective of this effort was to evaluate the mechanical behavior of C/SiC in various environments relevant to reusable launch vehicle applications. Stress-rupture testing was conducted at the NASA Glenn Research Center on C/SiC specimens in air and steam-containing environments. Also, the oxidation kinetics of the carbon fibers that reinforce the composite were monitored by thermogravimetric analysis in the same environments and temperatures used for the stress-rupture tests of the C/SiC composite specimens. The stress-rupture lives obtained for C/SiC tested in air and in steam/argon mixtures are shown in the following bar chart. As is typical for most materials, lives obtained at the lower temperature (600 C) are longer than for the higher temperature (1200 C). The effect of environment was most pronounced at the lower temperature, where the average test duration in steam at 600 C was at least 30 times longer than the lives obtained in air. The 1200 C data revealed little difference between the lives of specimens tested in air and steam at atmospheric pressure.

Intraperitoneal temperature and desiccation during endoscopic surgery. Intraoperative humidification and cooling of the peritoneal cavity can reduce adhesions.

PubMed

Corona, Roberta; Verguts, Jasper; Koninckx, Robert; Mailova, Karina; Binda, Maria Mercedes; Koninckx, Philippe R

2011-10-01

This study was conducted to document quantitatively the intraperitoneal temperature and desiccation during laparoscopic surgery. The temperature, relative humidity, and flow rate were measured in vitro and during laparoscopic surgery, at the entrance and at the exit of the abdomen. This permitted us to calculate desiccation for various flow rates using either dry CO(2) or CO(2) humidified with 100% relative humidity at any preset temperature between 25 and 37°C. The study showed that desiccation, both in vitro and in vivo, varies as expected with the flow rates and relative humidity while intraperitoneal temperature varies mainly with desiccation. Temperature regulation of bowels is specific and drops to the intraperitoneal temperature without affecting core body temperature. With a modified humidifier, desiccation could be eliminated while maintaining the intraperitoneal temperature between 31 to 32°C. Copyright © 2011 Mosby, Inc. All rights reserved.

43 CFR 3275.14 - What aspects of my geothermal operations must I measure?

Code of Federal Regulations, 2014 CFR

2014-10-01

... wellhead pressure. (b) For all electrical generation facilities, you must measure: (1) Steam and/or hot... steam and/or hot water exiting the facility. (c) For direct use facilities, you must measure: (1) Flow of steam and/or hot water; and (2) Temperature of the steam or water entering the facility. (d) We...

43 CFR 3275.14 - What aspects of my geothermal operations must I measure?

Code of Federal Regulations, 2011 CFR

2011-10-01

... wellhead pressure. (b) For all electrical generation facilities, you must measure: (1) Steam and/or hot... steam and/or hot water exiting the facility. (c) For direct use facilities, you must measure: (1) Flow of steam and/or hot water; and (2) Temperature of the steam or water entering the facility. (d) We...

43 CFR 3275.14 - What aspects of my geothermal operations must I measure?

Code of Federal Regulations, 2013 CFR

2013-10-01

... wellhead pressure. (b) For all electrical generation facilities, you must measure: (1) Steam and/or hot... steam and/or hot water exiting the facility. (c) For direct use facilities, you must measure: (1) Flow of steam and/or hot water; and (2) Temperature of the steam or water entering the facility. (d) We...

43 CFR 3275.14 - What aspects of my geothermal operations must I measure?

Code of Federal Regulations, 2012 CFR

2012-10-01

... wellhead pressure. (b) For all electrical generation facilities, you must measure: (1) Steam and/or hot... steam and/or hot water exiting the facility. (c) For direct use facilities, you must measure: (1) Flow of steam and/or hot water; and (2) Temperature of the steam or water entering the facility. (d) We...

40 CFR 86.117-96 - Evaporative emission enclosure calibrations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... this section. (v) r=FID response factor to methanol. (vi) PB=Barometric pressure, in. Hg. (kPa). (vii) T=Enclosure ambient temperature, R(K). (viii) i=Indicates initial reading. (ix) f=Indicates final reading. (x)(A) k=3.05. (B) For SI units, k=17.60. (xi) MHC, out=mass of hydrocarbon exiting the enclosure...

40 CFR 86.117-96 - Evaporative emission enclosure calibrations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... this section. (v) r=FID response factor to methanol. (vi) PB=Barometric pressure, in. Hg. (kPa). (vii) T=Enclosure ambient temperature, R(K). (viii) i=Indicates initial reading. (ix) f=Indicates final reading. (x)(A) k=3.05. (B) For SI units, k=17.60. (xi) MHC, out=mass of hydrocarbon exiting the enclosure...

Exhaust-Gas Pressure and Temperature Survey of F404-GE-400 Turbofan Engine

NASA Technical Reports Server (NTRS)

Walton, James T.; Burcham, Frank W., Jr.

1986-01-01

An exhaust-gas pressure and temperature survey of the General Electric F404-GE-400 turbofan engine was conducted in the altitude test facility of the NASA Lewis Propulsion System Laboratory. Traversals by a survey rake were made across the exhaust-nozzle exit to measure the pitot pressure and total temperature. Tests were performed at Mach 0.87 and a 24,000-ft altitude and at Mach 0.30 and a 30,000-ft altitude with various power settings from intermediate to maximum afterburning. Data yielded smooth pressure and temperature profiles with maximum jet temperatures approximately 1.4 in. inside the nozzle edge and maximum jet temperatures from 1 to 3 in. inside the edge. A low-pressure region located exactly at engine center was noted. The maximum temperature encountered was 3800 R.

The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

DOE PAGES

Liese, Eric; Zitney, Stephen E.

2017-06-26

A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liese, Eric; Zitney, Stephen E.

A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

Combustor flame flashback

NASA Technical Reports Server (NTRS)

Proctor, M. P.; Tien, J. S.

1985-01-01

A stainless steel, two-dimensional (rectangular), center-dump, premixed-prevaporized combustor with quartz window sidewalls for visual access was designed, built, and used to study flashback. A parametric study revealed that the flashback equivalence ratio decreased slightly as the inlet air temperature increased. It also indicated that the average premixer velocity and premixer wall temperature were not governing parameters of flashback. The steady-state velocity balance concept as the flashback mechanism was not supported. From visual observation several stages of burning were identified. High speed photography verified upstream flame propagation with the leading edge of the flame front near the premixer wall. Combustion instabilities (spontaneous pressure oscillations) were discovered during combustion at the dump plane and during flashback. The pressure oscillation frequency ranged from 40 to 80 Hz. The peak-to-peak amplitude (up to 1.4 psi) increased as the fuel/air equivalence ratio was increased attaining a maximum value just before flashback. The amplitude suddenly decreased when the flame stabilized in the premixer. The pressure oscillations were large enough to cause a local flow reversal. A simple test using ceramic fiber tufts indicated flow reversals existed at the premixer exit during flickering. It is suspected that flashback occurs through the premixer wall boundary layer flow reversal caused by combustion instability. A theoretical analysis of periodic flow in the premixing channel has been made. The theory supports the flow reversal mechanism.

Stream Water, Carbon and Total Nitrogen Load Responses to a Simulated Emerald Ash Borer Infestation in Black Ash Dominated Headwater Wetlands

NASA Astrophysics Data System (ADS)

Van Grinsven, M. J.; Shannon, J.; Noh, N. J.; Kane, E. S.; Bolton, N. W.; Davis, J.; Wagenbrenner, J.; Sebestyen, S. D.; Kolka, R.; Pypker, T. G.

2017-12-01

The rapid and extensive expansion of emerald ash borer (EAB) is considered an important ecological and economic disturbance, and will likely affect critical ecosystem services associated with black ash wetlands. It is unknown how EAB-induced disturbance in wetlands dominated with black ash will impact stream water, dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) export dynamics. We hypothesized that loads of water, DOC and TDN exported from black ash wetlands would be elevated following an EAB-induced disturbance. Stream water, DOC and TDN loads exiting two black ash wetlands in headwater watersheds in Michigan were quantified over a four-year period, and were combined with wetland soil temperature and soil decomposition rate monitoring to better understand the biogeochemical implications of an EAB-induced disturbance. After a two-year baseline monitoring period, an EAB disturbance was simulated by felling (ash-cut) all black ash trees with diameters greater than 2.5-cm in one wetland. When compared to the unaltered control, stream water DOC and TDN concentrations exiting the ash-cut wetland were significantly larger by 39% and 38%, respectively during the post-treatment study period. The significantly elevated DOC and TDN concentrations were likely associated with the higher soil temperatures and increased rates of soil decomposition detected in the ash-cut site during the post-treatment period. No significant mean daily stream discharge differences were detected between treatments during the pre-treatment period, however the 0.46 mm d-1 mean daily stream discharge exiting the ash-cut wetland was significantly smaller than the 1.07 mm d-1 exiting the unaltered control during the post-treatment study period. The significantly smaller daily stream discharge in the ash-cut site likely contributed to the fact no significant differences between treatments for either mean daily DOC loads or TDN loads were detected during the post-treatment period, despite the detection of significantly higher DOC and TDN concentrations. Examination of seasonal stream water, DOC and TDN export dynamics revealed the relative magnitudes of EAB-induced impacts were not evenly distributed throughout the year, and these differences have distinct seasonal implications for downstream waterbodies.

On the role of thermal backbone fluctuations in myoglobin ligand gate dynamics.

PubMed

Krokhotin, Andrey; Niemi, Antti J; Peng, Xubiao

2013-05-07

We construct an energy function that describes the crystallographic structure of sperm whale myoglobin backbone. As a model in our construction, we use the Protein Data Bank entry 1ABS that has been measured at liquid helium temperature. Consequently, the thermal B-factor fluctuations are very small, which is an advantage in our construction. The energy function that we utilize resembles that of the discrete nonlinear Schrödinger equation. Likewise, ours supports topological solitons as local minimum energy configurations. We describe the 1ABS backbone in terms of topological solitons with a precision that deviates from 1ABS by an average root-mean-square distance, which is less than the experimentally observed Debye-Waller B-factor fluctuation distance. We then subject the topological multi-soliton solution to extensive numerical heating and cooling experiments, over a very wide range of temperatures. We concentrate in particular to temperatures above 300 K and below the Θ-point unfolding temperature, which is around 348 K. We confirm that the behavior of the topological multi-soliton is fully consistent with Anfinsen's thermodynamic principle, up to very high temperatures. We observe that the structure responds to an increase of temperature consistently in a very similar manner. This enables us to characterize the onset of thermally induced conformational changes in terms of three distinct backbone ligand gates. One of the gates is made of the helix F and the helix E. The two other gates are chosen similarly, when open they provide a direct access route for a ligand to reach the heme. We find that out of the three gates we investigate, the one which is formed by helices B and G is the most sensitive to thermally induced conformational changes. Our approach provides a novel perspective to the important problem of ligand entry and exit.

On the role of thermal backbone fluctuations in myoglobin ligand gate dynamics

NASA Astrophysics Data System (ADS)

Krokhotin, Andrey; Niemi, Antti J.; Peng, Xubiao

2013-05-01

We construct an energy function that describes the crystallographic structure of sperm whale myoglobin backbone. As a model in our construction, we use the Protein Data Bank entry 1ABS that has been measured at liquid helium temperature. Consequently, the thermal B-factor fluctuations are very small, which is an advantage in our construction. The energy function that we utilize resembles that of the discrete nonlinear Schrödinger equation. Likewise, ours supports topological solitons as local minimum energy configurations. We describe the 1ABS backbone in terms of topological solitons with a precision that deviates from 1ABS by an average root-mean-square distance, which is less than the experimentally observed Debye-Waller B-factor fluctuation distance. We then subject the topological multi-soliton solution to extensive numerical heating and cooling experiments, over a very wide range of temperatures. We concentrate in particular to temperatures above 300 K and below the Θ-point unfolding temperature, which is around 348 K. We confirm that the behavior of the topological multi-soliton is fully consistent with Anfinsen's thermodynamic principle, up to very high temperatures. We observe that the structure responds to an increase of temperature consistently in a very similar manner. This enables us to characterize the onset of thermally induced conformational changes in terms of three distinct backbone ligand gates. One of the gates is made of the helix F and the helix E. The two other gates are chosen similarly, when open they provide a direct access route for a ligand to reach the heme. We find that out of the three gates we investigate, the one which is formed by helices B and G is the most sensitive to thermally induced conformational changes. Our approach provides a novel perspective to the important problem of ligand entry and exit.

Nonintrusive Temperature and Velocity Measurements in a Hypersonic Nozzle Flow

NASA Technical Reports Server (NTRS)

OByrne, S.; Danehy, P. M.; Houwing, A. F. P.

2002-01-01

Distributions of nitric oxide vibrational temperature, rotational temperature and velocity have been measured in the hypersonic freestream at the exit of a conical nozzle, using planar laser-induced fluorescence. Particular attention has been devoted to reducing the major sources of systematic error that can affect fluorescence tempera- ture measurements, including beam attenuation, transition saturation effects, laser mode fluctuations and transition choice. Visualization experiments have been performed to improve the uniformity of the nozzle flow. Comparisons of measured quantities with a simple one-dimensional computation are made, showing good agreement between measurements and theory given the uncertainty of the nozzle reservoir conditions and the vibrational relaxation rate.

Liquid level detector

DOEpatents

Grasso, A.P.

1984-02-21

A liquid level detector for low pressure boilers. A boiler tank, from which vapor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

Liquid level detector

DOEpatents

Grasso, Albert P.

1986-01-01

A liquid level detector for low pressure boilers. A boiler tank, from which apor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

Glove and mitten protection in extreme cold weather: an Antarctic study.

PubMed

Iserson, Kenneth V

2016-01-01

Background Myths, misconceptions and a general lack of information surround the use of gloves and mittens in extreme cold environments. Objective This study assessed how well an assortment of gloves and mittens performed in a very cold environment. Methods A convenience sample of gloves and mittens were tested in Antarctica during the winter of 2016 using a calibrated thermometer (range: -148°F to +158°F/-100°C to +70°C) three times over a 0.5-mile distance (~20 minutes). A small sensor on a 10-foot-long cable was taped to the radial surface of the distal small finger on the non-dominant hand. The tested clothing was donned over the probe, the maximum temperature inside the glove/mitten was established near a building exit (ambient temperature approximately 54°F/12°C), and the building was exited, initiating the test. The hand was kept immobile during the test. Some non-heated gloves were tested with chemical heat warmers placed over the volar or dorsal wrist. Results The highest starting (96°F/36°C) and ending (82°F/28°C) temperatures were with electrically heated gloves. The lowest starting temperature was with electrically heated gloves with the power off (63°F/17°C). Non-heated gloves with an inserted chemical hand warmer had the lowest minimum temperature (33°F/1°C). Maximum temperatures for gloves/mittens did not correlate well with their minimum temperature. Conclusions Coverings that maintained finger temperatures within a comfortable and safe range (at or above 59°F/15°C) included the heated gloves and mittens (including some with the power off) and mittens with liners. Mittens without liners (shell) generally performed better than unheated gloves. Better results generally paralleled the item's cost. Inserting chemical heat warmers at the wrist increased heat loss, possibly through the exposed area around the warmer.

Glove and mitten protection in extreme cold weather: an Antarctic study.

PubMed

Iserson, Kenneth V

2016-01-01

Myths, misconceptions and a general lack of information surround the use of gloves and mittens in extreme cold environments. This study assessed how well an assortment of gloves and mittens performed in a very cold environment. A convenience sample of gloves and mittens were tested in Antarctica during the winter of 2016 using a calibrated thermometer (range: -148°F to +158°F/-100°C to +70°C) three times over a 0.5-mile distance (~20 minutes). A small sensor on a 10-foot-long cable was taped to the radial surface of the distal small finger on the non-dominant hand. The tested clothing was donned over the probe, the maximum temperature inside the glove/mitten was established near a building exit (ambient temperature approximately 54°F/12°C), and the building was exited, initiating the test. The hand was kept immobile during the test. Some non-heated gloves were tested with chemical heat warmers placed over the volar or dorsal wrist. The highest starting (96°F/36°C) and ending (82°F/28°C) temperatures were with electrically heated gloves. The lowest starting temperature was with electrically heated gloves with the power off (63°F/17°C). Non-heated gloves with an inserted chemical hand warmer had the lowest minimum temperature (33°F/1°C). Maximum temperatures for gloves/mittens did not correlate well with their minimum temperature. Coverings that maintained finger temperatures within a comfortable and safe range (at or above 59°F/15°C) included the heated gloves and mittens (including some with the power off) and mittens with liners. Mittens without liners (shell) generally performed better than unheated gloves. Better results generally paralleled the item's cost. Inserting chemical heat warmers at the wrist increased heat loss, possibly through the exposed area around the warmer.

Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades

NASA Technical Reports Server (NTRS)

Flegel, Ashlie B.; Welch, Gerard E.; Giel, Paul W.; Ames, Forrest E.; Long, Jonathon A.

2015-01-01

Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to -51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05×106 to 2.12×106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.

The Relationship among Health Education Systems, Inc. Progression and Exit Examination Scores, Day or Evening Enrollment, Final Grade Point Average and NCLEX-RN® Success in Associate Degree Nursing Students

ERIC Educational Resources Information Center

Barnwell-Sanders, Pamela

2015-01-01

Graduates of associate degree (AD) nursing programs form the largest segment of first-time National Council Licensure Examination for Registered Nurses (NCLEX-RN®) test takers, yet also experience the highest rate of NCLEX-RN® failures. NCLEX-RN® failure delays entry into the profession, adding an emotional and financial toll to the unsuccessful…

Calculation of TIR Canopy Hot Spot and Implications for Earth Radiation Budget

NASA Technical Reports Server (NTRS)

Smith, J. A.; Ballard, J. R., Jr.

2000-01-01

Using a 3-D model for thermal infrared exitance and the Lowtran 7 atmospheric radiative transfer model, we compute the variation in brightness temperature with view direction and, in particular, the canopy thermal hot spot. We then perform a sensitivity analysis of surface energy balance components for a nominal case using a simple SVAT model given the uncertainty in canopy temperature arising from the thermal hot spot effect. Canopy thermal hot spot variations of two degrees C lead to differences of plus or minus 24% in the midday available energy.

The Impact of a Microfinance Program on Client Perceptions of the Quality of Care Provided by Private Sector Midwives in Uganda

PubMed Central

Agha, Sohail; Balal, Asma; Ogojo-Okello, Francis

2004-01-01

Objective To assess the impact of a microfinance program that provided business skills training and revolving loans to private sector midwives on perceived quality of services and client loyalty. Study Design A quasi-experimental study with a pretest, posttest design was used to evaluate the impact of the intervention. Exit interviews were conducted at 15 clinics that received the intervention and 7 clinics that did not. Baseline exit interviews were conducted between November and December 2000. Five days of business skills training were provided to midwives, and loans (averaging $454) were given during January and February 2001. A follow-up clinic visit was made to assess whether midwives were implementing what was emphasized during the training. The loans were to be repaid with interest within 6 to 12 months, at an interest rate that is standard within the local commercial market. For those who repaid the first set of loans (11 clinics), a second set of loans (averaging $742) was provided after June 2001. Follow-up exit interviews were conducted at the same clinics between February and March 2002. We assessed the effect of the intervention at both clinic and client levels. T-tests, the analysis of variance, and multivariate logistic regression analysis were conducted. Principal Findings These findings should be interpreted cautiously since secular trends were observed during the study period. The intervention was associated with improvement in clients' perceptions of the quality of care received at intervention clinics. The intervention was also associated with a higher level of client loyalty. Conclusions The enthusiastic response of midwives and the high loan repayment rate indicate that midwives were very receptive to the microfinance program. Overall, these findings suggest that microfinance may have an important role in strengthening private sector health services by increasing private providers' business skills and clients' satisfaction with services. PMID:15544645

The effects of leading edge and downstream film cooling on turbine vane heat transfer

NASA Astrophysics Data System (ADS)

Hylton, L. D.; Nirmalan, V.; Sultanian, B. K.; Kaufman, R. M.

1988-11-01

The progress under contract NAS3-24619 toward the goal of establishing a relevant data base for use in improving the predictive design capabilities for external heat transfer to turbine vanes, including the effect of downstream film cooling with and without leading edge showerhead film cooling. Experimental measurements were made in a two-dimensional cascade previously used to obtain vane surface heat transfer distributions on nonfilm cooled airfoils under contract NAS3-22761 and leading edge showerhead film cooled airfoils under contract NAS3-23695. The principal independent parameters (Mach number, Reynolds number, turbulence, wall-to-gas temperature ratio, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio) were maintained over ranges consistent with actual engine conditions and the test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. Data provide a data base for downstream film cooled turbine vanes and extends the data bases generated in the two previous studies. The vane external heat transfer obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The data obtained and presented illustrate the interaction of the variables and should provide the airfoil designer and computational analyst the information required to improve heat transfer design capabilities for film cooled turbine airfoils.

The effects of leading edge and downstream film cooling on turbine vane heat transfer

NASA Technical Reports Server (NTRS)

Hylton, L. D.; Nirmalan, V.; Sultanian, B. K.; Kaufman, R. M.

1988-01-01

The progress under contract NAS3-24619 toward the goal of establishing a relevant data base for use in improving the predictive design capabilities for external heat transfer to turbine vanes, including the effect of downstream film cooling with and without leading edge showerhead film cooling. Experimental measurements were made in a two-dimensional cascade previously used to obtain vane surface heat transfer distributions on nonfilm cooled airfoils under contract NAS3-22761 and leading edge showerhead film cooled airfoils under contract NAS3-23695. The principal independent parameters (Mach number, Reynolds number, turbulence, wall-to-gas temperature ratio, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio) were maintained over ranges consistent with actual engine conditions and the test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. Data provide a data base for downstream film cooled turbine vanes and extends the data bases generated in the two previous studies. The vane external heat transfer obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The data obtained and presented illustrate the interaction of the variables and should provide the airfoil designer and computational analyst the information required to improve heat transfer design capabilities for film cooled turbine airfoils.

Mechanistic studies of the CO-oxidation reaction on catalysts for use in long-life CO2 lasers

NASA Technical Reports Server (NTRS)

Dawood, Talat; Richmond, John R.; Riley, Brian W.

1990-01-01

The catalytic recombination of carbon monoxide and oxygen was studied under conditions expected to be present in a sealed E-beam CO2 laser system. These conditions are typically a gas inlet temperature of 60 C, a substoichiometric CO/O2 ratio of ca. 2.5/1 with an oxygen feed rate of ca. 5 micromoles/s, a carrier gas comprising He, N2 and CO2 in the ratio of 3:2:1, near atmospheric pressure and a gas velocity of 4 m/s. Heterogeneous catalysts, based on precious metal supported on tin oxide, have been coated onto ceramic monoliths and tested for catalytic activity and stability after a reduction/passivation step. Two catalyst systems have been chosen. These are Pt/Pd/SnO2 and Pt/Ru/SnO2. Under the conditions described above, a characteristic decline in catalytic activity is apparent for both systems, and exit gas temperature has been recognized as a sensitive parameter by which to monitor the activity changes. A semilogarithmic plot of exit temperature as a function of time has revealed two distinct processes connected with the decline in activity: one process is associated with reduction of the oxidized precious metal (at Site A), whilst the other is related to the formation and approach to steady-state of an active site at the metal/support interface (Site B).

The flow field of an underexpanded H2 jet coaxially injected into a hot free or ducted supersonic jet of air or nitrogen

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1977-01-01

Experimental data obtained in an investigation of the mixing of an underexpanded hydrogen jet in a supersonic flow both with and without combustion are presented. Tests were conducted in a Mach 2 test stream with both air and nitrogen as test media. Total temperature of the test stream was 2170 K, and static exit pressure was about one atmosphere. The static pressure at the exit of the hydrogen injector's Mach 2 nozzle was about two atmospheres. Primary measurements included shadowgraphs and pitot pressure surveys of the flow field. Pitot surveys and wall static pressures were measured for the case where the entire flow was shrouded. The results are compared to similar experimental data and theoretical predictions for the matched pressure case.

Graphite fiber reinforced thermoplastic resins

NASA Technical Reports Server (NTRS)

Navak, R. C.

1977-01-01

The results of a program designed to optimize the fabrication procedures for graphite thermoplastic composites are described. The properties of the composites as a function of temperature were measured and graphite thermoplastic fan exit guide vanes were fabricated and tested. Three thermoplastics were included in the investigation: polysulfone, polyethersulfone, and polyarylsulfone. Type HMS graphite was used as the reinforcement. Bending fatigue tests of HMS graphite/polyethersulfone demonstrated a gradual shear failure mode which resulted in a loss of stiffness in the specimens. Preliminary curves were generated to show the loss in stiffness as a function of stress and number of cycles. Fan exit guide vanes of HMS graphite polyethersulfone were satisfactorily fabricated in the final phase of the program. These were found to have stiffness and better fatigue behavior than graphite epoxy vanes which were formerly bill of material.

High-temperature, high-pressure oxygen metering valve

NASA Technical Reports Server (NTRS)

Christianson, Rollin C. (Inventor); Lycou, Peter P. (Inventor); Daniel, James A. (Inventor)

1993-01-01

A control valve includes a body defining a central cavity arranged between a fluid inlet and outwardly-diverging first and second fluid outlets respectively disposed in a common transverse plane. A valve member is arranged in the cavity for rotation between first and second operating positions where a transverse fluid passage through the valve member alternatively communicates the fluid inlet with one or the other of the fluid outlets. To minimize fluid turbulence when the valve member is rotated to an alternate operating position, the fluid passage has a convergent entrance for maintaining the passage in permanent communication with the fluid inlet as well as an oblong exit opening with spaced side walls for enabling the exit opening to temporarily span the first and second fluid outlets as the valve member is turned between its respective operating positions.

Computer code for predicting coolant flow and heat transfer in turbomachinery

NASA Technical Reports Server (NTRS)

Meitner, Peter L.

1990-01-01

A computer code was developed to analyze any turbomachinery coolant flow path geometry that consist of a single flow passage with a unique inlet and exit. Flow can be bled off for tip-cap impingement cooling, and a flow bypass can be specified in which coolant flow is taken off at one point in the flow channel and reintroduced at a point farther downstream in the same channel. The user may either choose the coolant flow rate or let the program determine the flow rate from specified inlet and exit conditions. The computer code integrates the 1-D momentum and energy equations along a defined flow path and calculates the coolant's flow rate, temperature, pressure, and velocity and the heat transfer coefficients along the passage. The equations account for area change, mass addition or subtraction, pumping, friction, and heat transfer.

The nature of the [TTF]˙+···[TTF]˙+ interactions in the [TTF]2(2+) dimers embedded in charged [3]catenanes: room-temperature multicenter long bonds.

PubMed

Capdevila-Cortada, Marçal; Novoa, Juan J

2012-04-23

The properties of tetrathiafulvalene dimers ([TTF](2)(2+)) and the functionalized ring-shaped bispropargyl (BPP)-functionalized TTF dimers, [BPP-TTF](2)(2+), found at room temperature in charged [3]catenanes, were evaluated by M06L calculations. The results showed that their isolated [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are energetically unstable towards dissociation. When enclosed in the 4(+)-charged central cyclophane ring of charged [3]catenanes (CBPQT(4+)), [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are also energetically unstable with respect to leaving the CBPQT(4+) ring; since the barrier for the exiting process is only about 3 kcal mol(-1), that is, within the reach of thermal energies at room temperature (neutral [TTF](2)(0) dimers are stable within the CBPQT(4+) ring). However, the [BPP-TTF](2)(2+) dimers in charged [3]catenanes cannot exit, because this would imply breaking the covalent bonds of the BPP-TTF(+) macrocycle. Finally, it was shown that the [TTF](2)(2+), [BPP-TTF](2)(2+) dimers, and charged [3]catenanes are energetically stable in solution and in crystals of their salts, in the first case due to the interactions with the solvent, and in the second case mostly due to cation-anion interactions. In these environmental conditions at room temperature the TTF units of the [BPP-TTF](2)(2+) dimers make short contacts, thus allowing their SOMO orbitals to overlap: a room-temperature multicenter long bond is formed, similar to those previously found in other [TTF](2)(2+) salts and their solutions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preliminary design of an alternate high-temperature turbine. A topical report for Phase II of the High-Temperature-Turbine Technology Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strough, R.I.

The feasibility of designing a convectively air-cooled turbine to operate in the environment of a 3000/sup 0/F combustor exit temperature with maximum turbine airfoil metal temperatures held to 1500/sup 0/F was established. The United Technologies-Kraftwerk Union V84.3 gas turbine design was used as the basic configuration for the design of the 3000/sup 0/F turbine. Turbine cooling requirements were determined based on the use of the modified V84.3 type silo combustor with a pattern factor of 0.1. The convective air-cooling technology levels in terms of cooling effectiveness required to satisfy the airfoil cooling requirements were identified. Cooling schemes and fabrication technologiesmore » required are discussed. Turbine airfoil cooling technology levels required for the 3000/sup 0/F engine were selected. The performance of the 3000/sup 0/F convectively air-cooled gas turbine in simple and combined cycle was calculated. The 3000/sup 0/F gas turbine combined-cycle system provides an increase in power of 61% and a decrease in heat rate of 10% compared to a similar system with a combustor exit temperature of 2210/sup 0/F and the same airflow. The development of a successful 3000/sup 0/F convectively air-cooled turbine can be accomplished with a reasonable design and fabrication development effort on the cooled turbine airfoils. Use of the convectively air-cooled turbine provides the transfer of technology from extensive aircraft engines developed programs and operating experience to industrial gas turbines. It eliminates the requirement for large investments in alternate cooling techniques tailored specifically for industrial engines which offer no additional benefits.« less

Perspectives On Dilution Jet Mixing

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Srinivasan, R.

1990-01-01

NASA recently completed program of measurements and modeling of mixing of transverse jets with ducted crossflow, motivated by need to design or tailor temperature pattern at combustor exit in gas turbine engines. Objectives of program to identify dominant physical mechanisms governing mixing, extend empirical models to provide near-term predictive capability, and compare numerical code calculations with data to guide future analysis improvement efforts.

Automatic coolant flow control device for a nuclear reactor assembly

DOEpatents

Hutter, E.

1984-01-27

A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.

Automatic coolant flow control device for a nuclear reactor assembly

DOEpatents

Hutter, Ernest

1986-01-01

A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.

SSME Turbopump Turbine Computations

NASA Technical Reports Server (NTRS)

Jorgenson, P. G. E.

1985-01-01

A two-dimensional viscous code was developed to be used in the prediction of the flow in the SSME high-pressure turbopump blade passages. The rotor viscous code (RVC) employs a four-step Runge-Kutta scheme to solve the two-dimensional, thin-layer Navier-Stokes equations. The Baldwin-Lomax eddy-viscosity model is used for these turbulent flow calculations. A viable method was developed to use the relative exit conditions from an upstream blade row as the inlet conditions to the next blade row. The blade loading diagrams are compared with the meridional values obtained from an in-house quasithree-dimensional inviscid code. Periodic boundary conditions are imposed on a body-fitted C-grid computed by using the GRAPE GRids about Airfoils using Poisson's Equation (GRAPE) code. Total pressure, total temperature, and flow angle are specified at the inlet. The upstream-running Riemann invariant is extrapolated from the interior. Static pressure is specified at the exit such that mass flow is conserved from blade row to blade row, and the conservative variables are extrapolated from the interior. For viscous flows the noslip condition is imposed at the wall. The normal momentum equation gives the pressure at the wall. The density at the wall is obtained from the wall total temperature.

Can Water-Injected Turbomachines Provide Cost-Effective Emissions and Maintenance Reductions?

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Daggett, David L.; Shouse, Dale T.; Roquemore, William M.; Brankovic, Andreja; Ryder, Robert C., Jr.

2011-01-01

An investigation has been performed to evaluate the effect of water injection on the performance of the Air Force Research Laboratory (AFRL, Wright-Patterson Air Force Base (WPAFB)) experimental trapped vortex combustor (TVC) over a range of fuel-to-air and water-to-fuel ratios. Performance is characterized by combustor exit quantities: temperature and emissions measurements using rakes, and overall pressure drop, from upstream plenum to combustor exit. Combustor visualization is performed using gray-scale and color still photographs and high-frame-rate videos. A parallel investigation evaluated the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid fueled combustor (e.g., TVC) that uses water injection for control of pollutant emissions and turbine inlet temperature. Generally, reasonable agreement is found between data and NO(x) computations. Based on a study assessing the feasibility and performance impact of using water injection on a Boeing 747-400 aircraft to reduce NO(x) emissions during takeoff, retrofitting does not appear to be cost effective; however, an operator of a newly designed engine and airframe might be able to save up to 1.0 percent in operating costs. Other challenges of water injection will be discussed.

Lightning attachment patterns and flight conditions experienced by the NASA F-106B airplane from 1980 to 1983

NASA Technical Reports Server (NTRS)

Fisher, B. D.; Plumer, J. A.

1984-01-01

The direct lightning strike data and associated flight conditions recorded from 1980 to 1983 during 742 thunderstorm penetrations with a NASA F-106B in Oklahoma and Virginia are studied with an emphasis on aircraft protection design. The individual lightning attachment spots were plotted on isometric projections of the aircraft to identify lightning entry and exit points and swept flash patterns. The altitudes, ambient temperatures, turbulence, and precipitation at which the strikes occurred are summarized and discussed. It was noted that peak strike rates (0.81 strikes/min and 3 strikes/penetration) occurred at altitudes between 11 km and 11.6 km corresponding to ambient temperatures between -40 C and -45 C. The data confirmed that initial entry and exit points most frequently occur at aircraft extremities, in this case the nose boom, the wing tips, the vertical fin cap, and the afterburner. The swept-flash attachment paths and burn marks found in this program indicate that the mid-span areas of swept aircraft may be more susceptible to lightning than previously thought. It was also found that lightning strikes may attach to spots within the engine tail pipe.

Control methods and systems for indirect evaporative coolers

DOEpatents

Woods, Jason; Kozubal, Erik

2015-09-22

A control method for operating an indirect evaporative cooler to control temperature and humidity. The method includes operating an airflow control device to provide supply air at a flow rate to a liquid desiccant dehumidifier. The supply air flows through the dehumidifier and an indirect evaporative cooler prior to exiting an outlet into a space. The method includes operating a pump to provide liquid desiccant to the liquid desiccant dehumidifier and sensing a temperature of an airstream at the outlet of the indirect evaporative cooler. The method includes comparing the temperature of the airstream at the outlet to a setpoint temperature at the outlet and controlling the pump to set the flow rate of the liquid desiccant. The method includes sensing space temperature, comparing the space temperature with a setpoint temperature, and controlling the airflow control device to set the flow rate of the supply air based on the comparison.

NO formation in the burnout region of a partially premixed methane-air flame with upstream heat loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mokhov, A.V.; Levinsky, H.B.

Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemicalmore » reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that {approximately}40 ppm of NO are produced in this burnout region, at temperatures between {approximately}2,100 K and {approximately}1,900 K, probably via the Zeldovich mechanism. Reducing the exit velocity of 12 cm/s reduces the flame temperature substantially, and effectively eliminates this contribution. At velocities of 12 and 8 cm/s, {approximately}10 ppm of NO are formed in the burnout region, even though the gas temperatures are too low for Zeldovich NO to be significant. Although the mechanism responsible for these observations is as yet unclear, the results are consistent with the idea that the low temperatures in the fuel-rich gases caused by upstream heat loss retard the conversion of HCN (formed via the Fenimore mechanism) to NO, with this residual HCN then being converted to NO during burnout.« less

High sustained average power cw and ultrafast Yb:YAG near-diffraction-limited cryogenic solid-state laser.

PubMed

Brown, David C; Singley, Joseph M; Kowalewski, Katie; Guelzow, James; Vitali, Victoria

2010-11-22

We report what we believe to be record performance for a high average power Yb:YAG cryogenic laser system with sustained output power. In a CW oscillator-single-pass amplifier configuration, 963 W of output power was measured. In a second configuration, a two amplifier Yb:YAG cryogenic system was driven with a fiber laser picosecond ultrafast oscillator at a 50 MHz repetition rate, double-passed through the first amplifier and single-passed through the second, resulting in 758 W of average power output. Pulses exiting the system have a FWHM pulsewidth of 12.4 ps, an energy/pulse of 15.2 μJ, and a peak power of 1.23 MW. Both systems are force convection-cooled with liquid nitrogen and have been demonstrated to run reliably over long time periods.

[Monitoring and analysis on evolution process of rainfall runoff water quality in urban area].

PubMed

Dong, Wen; Li, Huai-En; Li, Jia-Ke

2013-02-01

In order to find the water quality evolution law and pollution characteristics of the rainfall runoff from undisturbed to the neighborhood exit, 6 times evolution process of rainfall runoff water quality were monitored and analyzed from July to October in 2011, and contrasted the clarification efficiency of the grassland to the roof runoff rudimentarily at the same time. The research showed: 1. the results of the comparison from "undisturbed, rainfall-roof, rainfall runoff-road, rainfall-runoff the neighborhood exit runoff " showed that the water quality of the undisturbed rain was better than that from the roof and the neighborhood exist, but the road rainfall runoff water quality was the worst; 2. the average concentrations of the parameters such as COD, ammonia nitrogen and total nitrogen all exceeded the Fifth Class of the Surface Water Quality Standard except for the soluble total phosphorus from undisturbed rainfall to the neighborhood exit; 3. the runoff water quality of the short early fine days was better than that of long early fine days, and the last runoff water quality was better than that of the initial runoff in the same rainfall process; 4. the concentration reduction of the grassland was notable, and the reduction rate of the grassland which is 1.0 meter wide of the roof runoff pollutants such as COD and nitrogen reached 30%.

Radiation Dose Uncertainty and Correction for a Mouse Orthotopic and Xenograft Irradiation Model

PubMed Central

Gan, Gregory N.; Altunbas, Cem; Morton, John J.; Eagles, Justin; Backus, Jennifer; Dzingle, Wayne; Raben, David; Jimeno, Antonio

2016-01-01

Purpose In animal irradiation models, reported dose can vary significantly from the actual doses delivered. We describe an effective method for in vivo dose verification. Materials and Methods Mice bearing commercially-available cell line or patient-derived tumor cell orthotopic or flank xenografts were irradiated using a 160 kVp, 25 mA X-ray source. Entrance dose was evaluated using optically-stimulated luminescence dosimeters (OSLD) and exit dose was assessed using radiochromic film dosimetry. Results Tumor position within the irradiation field was validated using external fiducial markers. The average entrance dose in orthotopic tumors from 10 OSLDs placed on 2 different animal irradiation days was 514±37 cGy (range: 437–545). Exit dose measurements taken from 7 radiochromic films on two separate days were 341±21 cGy (a 34% attenuation). Flank tumor irradiation doses measured by OSLD were 368±9 cGy compared to exit doses of 330 cGy measured by radiochromic film. Conclusion Variations related to the irradiation model can lead to significant under or over- dosing in vivo which can affect tumor control and/or biologic endpoints that are dose dependent. We recommend that dose measurements be determined empirically based on the mouse model and irradiator used and dose compensation adjustments performed to ensure correct and appropriate doses. PMID:26689828

Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade at Low Inlet Turbulence

NASA Technical Reports Server (NTRS)

Flegel-McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

2013-01-01

Aerodynamic measurements obtained in a transonic linear cascade were used to assess the impact of large incidence angle and Reynolds number variations on the 3-D flow field and midspan loss and turning of a 2-D section of a variable-speed power-turbine (VSPT) rotor blade. Steady-state data were obtained for ten incidence angles ranging from +15.8 deg to -51.0 deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×10(exp 5) to 2.12×10(exp 6). Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan total-pressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8 deg and -36.7 deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures. Tests were conducted in the NASA Glenn Transonic Turbine Blade Cascade Facility. The measurements reflect strong secondary flows associated with the high aerodynamic loading levels at large positive incidence angles and an increase in loss levels with decreasing Reynolds number. The secondary flows decrease with negative incidence as the blade becomes unloaded. Transitional flow is admitted in this low inlet turbulence dataset, making it a challenging CFD test case. The dataset will be used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range. deg

Fluorescent refrigeration

DOEpatents

Epstein, Richard I.; Edwards, Bradley C.; Buchwald, Melvin I.; Gosnell, Timothy R.

1995-01-01

Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement.

Fluorescent refrigeration

DOEpatents

Epstein, R.I.; Edwards, B.C.; Buchwald, M.I.; Gosnell, T.R.

1995-09-05

Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement. 6 figs.

An improved image alignment procedure for high-resolution transmission electron microscopy.

PubMed

Lin, Fang; Liu, Yan; Zhong, Xiaoyan; Chen, Jianghua

2010-06-01

Image alignment is essential for image processing methods such as through-focus exit-wavefunction reconstruction and image averaging in high-resolution transmission electron microscopy. Relative image displacements exist in any experimentally recorded image series due to the specimen drifts and image shifts, hence image alignment for correcting the image displacements has to be done prior to any further image processing. The image displacement between two successive images is determined by the correlation function of the two relatively shifted images. Here it is shown that more accurate image alignment can be achieved by using an appropriate aperture to filter the high-frequency components of the images being aligned, especially for a crystalline specimen with little non-periodic information. For the image series of crystalline specimens with little amorphous, the radius of the filter aperture should be as small as possible, so long as it covers the innermost lattice reflections. Testing with an experimental through-focus series of Si[110] images, the accuracies of image alignment with different correlation functions are compared with respect to the error functions in through-focus exit-wavefunction reconstruction based on the maximum-likelihood method. Testing with image averaging over noisy experimental images from graphene and carbon-nanotube samples, clear and sharp crystal lattice fringes are recovered after applying optimal image alignment. Copyright 2010 Elsevier Ltd. All rights reserved.

Effect of iron particle size and volume fraction on the magnetic properties of Fe/silicate glass soft magnetic composites

NASA Astrophysics Data System (ADS)

Ding, Wei; Jiang, Longtao; Liao, Yaqin; Song, Jiabin; Li, Bingqing; Wu, Gaohui

2015-03-01

Fe/silicate glass soft magnetic composites (SMC) were fabricated by powder metallurgy with 1000 MPa pressure at room temperature, and then annealed at 700 °C for 90 min. The iron particles distributed uniformly in the composites, and have been separated from each other by a continuous silicate glass insulating layer. Fe/glass interface was well bonded and a quasi-continuous layer Fe3O4 and FeO exited. Very fine crystalline phases Na12Ca3Fe2(Si6O18)2 were formed in silicate glass. Composite containing 57 vol% 75 μm iron particles demonstrated highest resistivity of 7.8×10-3 Ω m. The μm, Bs and Bt increased while Hc of Fe/silicate glass composites decreased with the increase of average size of iron particles. The composite with highest amount (82 vol%) and largest average size (140 μm) of iron particles demonstrated best μm, Bs and Bt and Hc, which were 622, 1.57 T, 1.43 T, 278 A/m, respectively. The composite containing 57 vol% 75 μm iron particles demonstrated minimum core loss of 3.5 W/kg at 50 Hz and 28.1 W/kg at 400 Hz, while the composite containing 82 vol% 140 μm iron particles exhibited maximum core loss of 5.2 W/kg at 50 Hz and 67.7 W/kg at 400 Hz.

Simulation of a Synthetic Jet in Quiescent Air Using TLNS3D Flow Code

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Turkel, Eli

2007-01-01

Although the actuator geometry is highly three-dimensional, the outer flowfield is nominally two-dimensional because of the high aspect ratio of the rectangular slot. For the present study, this configuration is modeled as a two-dimensional problem. A multi-block structured grid available at the CFDVAL2004 website is used as a baseline grid. The periodic motion of the diaphragm is simulated by specifying a sinusoidal velocity at the diaphragm surface with a frequency of 450 Hz, corresponding to the experimental setup. The amplitude is chosen so that the maximum Mach number at the jet exit is approximately 0.1, to replicate the experimental conditions. At the solid walls zero slip, zero injection, adiabatic temperature and zero pressure gradient conditions are imposed. In the external region, symmetry conditions are imposed on the side (vertical) boundaries and far-field conditions are imposed on the top boundary. A nominal free-stream Mach number of 0.001 is imposed in the free stream to simulate incompressible flow conditions in the TLNS3D code, which solves compressible flow equations. The code was run in unsteady (URANS) mode until the periodicity was established. The time-mean quantities were obtained by running the code for at least another 15 periods and averaging the flow quantities over these periods. The phase-locked average of flow quantities were assumed to be coincident with their values during the last full time period.

Analysis of a Radioisotope Thermal Rocket Engine

NASA Technical Reports Server (NTRS)

Machado-Rodriguez, Jonathan P.; Landis, Geoffrey A.

2016-01-01

The Triton Hopper is a concept for a global hopper vehicle which uses a radioisotope rocket engine and In-situ propellant acquisition to explore the surface of Neptune's moon, Triton. The current Triton Hopper concept stores heated Nitrogen in a spherical tank to be used as the propellant. The aim of the research was to investigate the benefits of storing propellant at ambient temperature and heating it through the use of a thermal block during engine operation, as opposed to storing gas at a high temperature. Lithium, Lithium Fluoride and Beryllium were considered as possible materials for the thermal block. A heat energy analysis indicated that a lithium thermal mass would provide the highest heat energy for a temperature change from 900 Celsius to -100 Celsius. A heat transfer analysis was performed for Nitrogen at -100 Celsius flowing through 1000 passages inside a 1kg lithium thermal block at a temperature of 900 Celsius. The system was analyzed as turbulent flow through a tube with constant surface temperature. The analysis indicated that the propellant reached a maximum temperature of 877 Celsius before entering the nozzle. At this exit temperature, the average specific impulse [I(sub sp)] of the engine was determined to be 157s. Previous studies for the stored heated gas concept suggest that the engine would have an average I(sub sp) of approximately 52s. Thus, the use of a thermal block concept results in a 200 percent engine performance increase. In addition, a tank sizing study was performed to determine if the concept is feasible in terms of mass requirements. The mass for a spherical carbon fiber COPV storing 35kg of nitrogen at an initial temperature of -100 Celsius and a pressure of 1000psia, was determined to be 7.2kg. The specific impulse analysis indicated that the maximum engine performance is obtained for a mass ratio of 5kg of Nitrogen per every 1kg of lithium thermal mass. Thus for 35kg of Nitrogen the total thermal mass would be 7kg. This brings the total mass of the system to 49.2.kg which is less than the 56kg landing payload capacity of the Triton Hopper. Finally, an insulation analysis using 10mm of MLI insulation indicated that a total of 22 watts of heat are lost to the environment. With the heat loss known, the power required to heat the thermal mass to 900 Celsius in 24 days was determined to be 2.15 watts. The study's results allowed us to conclude that the thermal mass concept is the better option due to the performance increase provided, the low power requirement and its compliance with the landing mass requirement of the Triton Hopper.

An Experimental Investigation of the Flow Structure of Supersonic Impinging Jets

NASA Technical Reports Server (NTRS)

Henderson, Brenda; Bridges, James; Wernet, Mark

2002-01-01

An experimental investigation into the jet structure associated with sound production by a supersonic impinging jet is presented. Large plate impinging tones are investigated for a nozzle pressure ratio (NPR) of 4 and nozzle-to-plate spacings between 1 and 5 nozzle exit diameters, where NPR is equal to the ratio of the stagnation pressure to the pressure at the nozzle lip. Results from phase-locked shadowgraph and phase-averaged digital particle image velocimetry (DPIV) studies indicate that, during the oscillation cycle, the Mach disk oscillates axially, a well defined recirculation zone is created in the subsonic impingement region and moves toward the plate, and the compression and expansion regions in the outer supersonic flow move downstream, Sound appears to be generated in the wall jet at approximately 2.6R from the jet axis, where R is the nozzle exit radius. The oscillatory motion in the wall jet is the result of the periodic fluid motion in the near wall region.

Conjugate Heat Transfer Analyses on the Manifold for Ramjet Fuel Injectors

NASA Technical Reports Server (NTRS)

Wang, Xiao-Yen J.

2006-01-01

Three-dimensional conjugate heat transfer analyses on the manifold located upstream of the ramjet fuel injector are performed using CFdesign, a finite-element computational fluid dynamics (CFD) software. The flow field of the hot fuel (JP-7) flowing through the manifold is simulated and the wall temperature of the manifold is computed. The three-dimensional numerical results of the fuel temperature are compared with those obtained using a one-dimensional analysis based on empirical equations, and they showed a good agreement. The numerical results revealed that it takes around 30 to 40 sec to reach the equilibrium where the fuel temperature has dropped about 3 F from the inlet to the exit of the manifold.

29 CFR 1917.122 - Employee exits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Employee exits. 1917.122 Section 1917.122 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.122 Employee exits. (a) Employee exits shall be clearly marked. (b) If an employee exit is not visible from employees' work stations, directional signs...

Advanced Diesel Oil Fuel Processor Development

DTIC Science & Technology

1986-06-01

water exit 29 sample quencher: gas sample line inlet 30 sample quencher: gas sample line exit 31 sample quencher: cooling water inlet 32 desulfuriser ...exit line 33, 34 desulfurimer 35 heat exchanger: process gas exit (to desulfuriser ) 38 shift reactor inlet (top) 37 shift reactor: cooling air exit

Prediction of soot and thermal radiation in a model gas turbine combustor burning kerosene fuel spray at different swirl levels

NASA Astrophysics Data System (ADS)

Ghose, Prakash; Patra, Jitendra; Datta, Amitava; Mukhopadhyay, Achintya

2016-05-01

Combustion of kerosene fuel spray has been numerically simulated in a laboratory scale combustor geometry to predict soot and the effects of thermal radiation at different swirl levels of primary air flow. The two-phase motion in the combustor is simulated using an Eulerian-Lagragian formulation considering the stochastic separated flow model. The Favre-averaged governing equations are solved for the gas phase with the turbulent quantities simulated by realisable k-ɛ model. The injection of the fuel is considered through a pressure swirl atomiser and the combustion is simulated by a laminar flamelet model with detailed kinetics of kerosene combustion. Soot formation in the flame is predicted using an empirical model with the model parameters adjusted for kerosene fuel. Contributions of gas phase and soot towards thermal radiation have been considered to predict the incident heat flux on the combustor wall and fuel injector. Swirl in the primary flow significantly influences the flow and flame structures in the combustor. The stronger recirculation at high swirl draws more air into the flame region, reduces the flame length and peak flame temperature and also brings the soot laden zone closer to the inlet plane. As a result, the radiative heat flux on the peripheral wall decreases at high swirl and also shifts closer to the inlet plane. However, increased swirl increases the combustor wall temperature due to radial spreading of the flame. The high incident radiative heat flux and the high surface temperature make the fuel injector a critical item in the combustor. The injector peak temperature increases with the increase in swirl flow mainly because the flame is located closer to the inlet plane. On the other hand, a more uniform temperature distribution in the exhaust gas can be attained at the combustor exit at high swirl condition.

Using standard and institutional mentorship models to implement SLMTA in Kenya

PubMed Central

Mwalili, Samuel; Basiye, Frank L.; Zeh, Clement; Emonyi, Wilfred I.; Langat, Raphael; Luman, Elizabeth T.; Mwangi, Jane

2014-01-01

Background Kenya is home to several high-performing internationally-accredited research laboratories, whilst most public sector laboratories have historically lacked functioning quality management systems. In 2010, Kenya enrolled an initial eight regional and four national laboratories into the Strengthening Laboratory Management Toward Accreditation (SLMTA) programme. To address the challenge of a lack of mentors for the regional laboratories, three were paired, or ‘twinned’, with nearby accredited research laboratories to provide institutional mentorship, whilst the other five received standard mentorship. Objectives This study examines results from the eight regional laboratories in the initial SLMTA group, with a focus on mentorship models. Methods Three SLMTA workshops were interspersed with three-month periods of improvement project implementation and mentorship. Progress was evaluated at baseline, mid-term, and exit using the Stepwise Laboratory Quality Improvement Process Towards Accreditation (SLIPTA) audit checklist and scores were converted into a zero- to five-star scale. Results At baseline, the mean score for the eight laboratories was 32%; all laboratories were below the one-star level. At mid-term, all laboratories had measured improvements. However, the three twinned laboratories had increased an average of 32 percentage points and reached one to three stars; whilst the five non-twinned laboratories increased an average of 10 percentage points and remained at zero stars. At exit, twinned laboratories had increased an average 12 additional percentage points (44 total), reaching two to four stars; non-twinned laboratories increased an average of 28 additional percentage points (38 total), reaching one to three stars. Conclusion The partnership used by the twinning model holds promise for future collaborations between ministries of health and state-of-the-art research laboratories in their regions for laboratory quality improvement. Where they exist, such laboratories may be valuable resources to be used judiciously so as to accelerate sustainable quality improvement initiated through SLMTA. PMID:29043191

Spatial connectivity in a highly heterogeneous aquifer: From cores to preferential flow paths

USGS Publications Warehouse

Bianchi, M.; Zheng, C.; Wilson, C.; Tick, G.R.; Liu, Gaisheng; Gorelick, S.M.

2011-01-01

This study investigates connectivity in a small portion of the extremely heterogeneous aquifer at the Macrodispersion Experiment (MADE) site in Columbus, Mississippi. A total of 19 fully penetrating soil cores were collected from a rectangular grid of 4 m by 4 m. Detailed grain size analysis was performed on 5 cm segments of each core, yielding 1740 hydraulic conductivity (K) estimates. Three different geostatistical simulation methods were used to generate 3-D conditional realizations of the K field for the sampled block. Particle tracking calculations showed that the fastest particles, as represented by the first 5% to arrive, converge along preferential flow paths and exit the model domain within preferred areas. These 5% fastest flow paths accounted for about 40% of the flow. The distribution of preferential flow paths and particle exit locations is clearly influenced by the occurrence of clusters formed by interconnected cells with K equal to or greater than the 0.9 decile of the data distribution (10% of the volume). The fraction of particle paths within the high-K clusters ranges from 43% to 69%. In variogram-based K fields, some of the fastest paths are through media with lower K values, suggesting that transport connectivity may not require fully connected zones of relatively homogenous K. The high degree of flow and transport connectivity was confirmed by the values of two groups of connectivity indicators. In particular, the ratio between effective and geometric mean K (on average, about 2) and the ratio between the average arrival time and the arrival time of the fastest particles (on average, about 9) are consistent with flow and advective transport behavior characterized by channeling along preferential flow paths. ?? 2011 by the American Geophysical Union.

Neurology residency training in Europe--the current situation.

PubMed

Struhal, W; Sellner, J; Lisnic, V; Vécsei, L; Müller, E; Grisold, W

2011-04-01

Little is known about neurological training curricula in Europe. A joint approach by the European Federation of Neurological Societies (EFNS), the Union of European Medical Specialists/European Board of Neurology and the European Association of Young Neurologist and Trainees was established to explore the spectrum of neurology training in Europe. In 2006, a questionnaire-based survey on neurology curricula as well as demographic data was designed by WS and WG and distributed by the EFNS to the national delegates of the EFNS, which comprises all European countries and Israel. By 2009, delegates from 31 of 41 countries (representing 76% of 505 million) had returned the questionnaire. A total of 24,165 specialists (46% women) were registered in the 31 countries. This corresponds to an average of 6.6 neurologists per 100,000 inhabitants (range 0.9-17.4/100,000 inhabitants). Duration of training in Europe was on average 4.9,years, ranging from 3 to 6,years. The number of residents interested in neurological training exceeded the amount of available training positions. Performance of neurological trainees was regularly assessed in 26 countries (84%), usually by recurrent clinical evaluation. Board examinations were held in 23 countries (74%). Interim examinations were performed in three countries, exit examinations in 14 and both interim and exit examination in 6. Considerable differences were also found in manpower (0.9-17.4 neurologists/100,000 inhabitants) and working conditions (e.g. average weekly working hours ranging from 30-80 h/month). We found a significant positive correlation between manpower and theoretical training hours. Considerable differences exist in training curricula of European countries. These data might provide the basis for European training and quality assurance initiatives. © 2010 The Author(s). European Journal of Neurology © 2010 EFNS.

Method for removing oxide contamination from titanium diboride powder

DOEpatents

Brynestad, J.; Bamberger, C.E.

A method for removing oxide contamination from titanium diboride powder involves the direct chemical treatment of TiB/sub 2/ powders with a gaseous boron halide, such as BCl/sub 3/, at temperatures in the range of 500 to 800/sup 0/C. The BCl/sub 3/ reacts with the oxides to form volatile species which are removed by the BCl/sub 3/ exit stream.

Method for removing oxide contamination from titanium diboride powder

DOEpatents

Brynestad, Jorulf; Bamberger, Carlos E.

1984-01-01

A method for removing oxide contamination from titanium diboride powder involves the direct chemical treatment of TiB.sub.2 powders with a gaseous boron halide, such as BCl.sub.3, at temperatures in the range of 500.degree.-800.degree. C. The BCl.sub.3 reacts with the oxides to form volatile species which are removed by the BCl.sub.3 exit stream.

First experiments with e-/H- plasmas: Enhanced centrifugal separation from diocotron mode damping

NASA Astrophysics Data System (ADS)

Kabantsev, A. A.; Thompson, K. A.; Driscoll, C. F.

2018-01-01

Negative hydrogen ions are produced and contained within a room-temperature electron plasma, by dissociative electron attachment onto exited H2 neutrals. We observe a strongly enhanced centrifugal separation of electrons and ions when a diocotron mode is present. The outward ion transport rate is proportional to the diocotron mode amplitude, with concurrent diocotron mode damping. This is not yet understood theoretically.

The Background to Current Theories of Scuffing

DTIC Science & Technology

1973-01-01

attention because, by neglecting axial flow , it can be treated in two dimensions. This has resulted in a fairly complete theoretical analysis...the contact. This method was essentially one of measuring the volume rate of flow through the contact, which was directly related to the pad...exit constriction. The pressure and temperature were also measured in the axial direction (105) and the results indicated that side leakage was

Simbol-X Mirror Module Thermal Shields: I-Design and X-Ray Transmission

NASA Astrophysics Data System (ADS)

Collura, A.; Barbera, M.; Varisco, S.; Basso, S.; Pareschi, G.; Tagliaferri, G.; Ayers, T.

2009-05-01

The Simbol-X mission is designed to fly in formation flight configuration. As a consequence, the telescope has both ends open to space, and thermal shielding at telescope entrance and exit is required to maintain temperature uniformity throughout the mirrors. Both mesh and meshless solutions are presently under study for the shields. We discuss the design and the X-ray transmission.

Effects of nozzle exit geometry and pressure ratio on plume shape for nozzles exhausting into quiescent air

NASA Technical Reports Server (NTRS)

Scallion, William I.

1991-01-01

The effects of varying the exit geometry on the plume shapes of supersonic nozzles exhausting into quiescent air at several exit-to-ambient pressure ratios are given. Four nozzles having circular throat sections and circular, elliptical and oval exit cross sections were tested and the exit plume shapes are compared at the same exit-to-ambient pressure ratios. The resulting mass flows were calculated and are also presented.

Method of increasing power within an optical cavity with long path lengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leen, John Brian; Bramall, Nathan E.

A cavity-enhanced absorption spectroscopy instrument has an optical cavity with two or more cavity mirrors, one mirror of which having a hole or other aperture for injecting a light beam, and the same or another mirror of which being partially transmissive to allow exit of light to a detector. A spherical-spherical configuration with at least one astigmatic mirror or a spherical-cylindrical configuration where the spherical mirror could also be astigmatic prevents a reentrant condition wherein the injected beam would prematurely exit the cavity through the aperture. This combination substantially increases the number of passes of the injected beam through amore » sample volume for sensitive detection of chemical species even in less than ideal conditions including low power laser or LED sources, poor mirror reflectivity or detector noise at the wavelengths of interest, or cavity alignment issues such as vibration or temperature and pressure changes.« less

Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

NASA Technical Reports Server (NTRS)

Choi, Maria

2016-01-01

An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HP Hall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.

Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

NASA Technical Reports Server (NTRS)

Choi, Maria

2016-01-01

An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HPHall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.

Electronically conductive perovskite-based oxide nanoparticles and films for optical sensing applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohodnicki, Jr., Paul R; Schultz, Andrew M

2015-04-28

The disclosure relates to a method of detecting a change in a chemical composition by contacting a electronically conducting perovskite-based metal oxide material with a monitored stream, illuminating the electronically conducting perovskite-based metal oxide with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The electronically conducting perovskite-based metal oxide has a perovskite-based crystal structure and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The electronically conducting perovskite-based metal oxide hasmore » an empirical formula A.sub.xB.sub.yO.sub.3-.delta., where A is at least a first element at the A-site, B is at least a second element at the B-site, and where 0.8« less

High freestream turbulence studies on a scaled-up stator vane

NASA Astrophysics Data System (ADS)

Radomsky, Roger William, Jr.

2000-10-01

Today's gas turbine engines are operating at combustor exit temperatures far exceeding the maximum temperatures of the component alloys downstream of the combustor. These higher temperatures are necessary to increase the efficiency of the engine, and, as such, durability of the downstream components becomes an issue. The highly turbulent flowfield that exists at the exit of the combustor complicates issues further by increasing heat transfer from the hot gas to the component surface. To account for the high heat transfer rates, and provide a better prediction of the applied heat loads, detailed heat transfer and flowfield information is needed at turbulence levels representative those exiting a combustor. Flowfield measurements at high freestream turbulence levels indicated that turbulence, which was isotropic at the inlet, became highly anisotropic in the test section as a result of surface curvature and strain. Turbulent kinetic energy levels were shown to increase in the passage by as much as 131% and 31% for the 10% and 19.5% turbulence levels. Although the turbulent kinetic energy was high, the turbulence level based upon local velocity decreased quickly to levels of 3% and 6% near the suction surface for the 10% and 19.5% turbulence levels. For the pressure surface, local turbulence levels were as high as 10% and 16% for the 10% and 19.5% turbulence levels. High local turbulence levels and heat transfer augmentation were observed near the stagnation location, by as much as 50%, and along the pressure surface, by as much as 80%, where airfoil geometries have shown degradation after prolonged usage. Endwall flowfield measurements on a plane at the stagnation location showed that a horseshoe vortex developed in the juncture region of the vane at high freestream. turbulence similar to that at low freestream turbulence. Measurements near the center of the vortex indicated that the vortex was highly unsteady. In regions where strong secondary flows (horseshoe and passage vortex) were present, these vortices dominated the heat transfer and the augmentations due to high freestream turbulence were small.

14 CFR 27.805 - Flight crew emergency exits.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Flight crew emergency exits. 27.805 Section... § 27.805 Flight crew emergency exits. (a) For rotorcraft with passenger emergency exits that are not convenient to the flight crew, there must be flight crew emergency exits, on both sides of the rotorcraft or...

14 CFR 29.805 - Flight crew emergency exits.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Flight crew emergency exits. 29.805 Section... Accommodations § 29.805 Flight crew emergency exits. (a) For rotorcraft with passenger emergency exits that are not convenient to the flight crew, there must be flight crew emergency exits, on both sides of the...

14 CFR 29.805 - Flight crew emergency exits.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Flight crew emergency exits. 29.805 Section... Accommodations § 29.805 Flight crew emergency exits. (a) For rotorcraft with passenger emergency exits that are not convenient to the flight crew, there must be flight crew emergency exits, on both sides of the...

14 CFR 27.805 - Flight crew emergency exits.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Flight crew emergency exits. 27.805 Section... § 27.805 Flight crew emergency exits. (a) For rotorcraft with passenger emergency exits that are not convenient to the flight crew, there must be flight crew emergency exits, on both sides of the rotorcraft or...

Theoretical performance of some rocket propellants containing hydrogen, nitrogen, and oxygen

NASA Technical Reports Server (NTRS)

Miller, Riley O; Ordin, Paul M

1948-01-01

Theoretical performance data including nozzle-exit temperature, specific impulse, volume specific impulse and composition, temperature, and mean molecular weight of reaction products based on frozen equilibrium and isentropic expansion are presented for 13 propellant combinations at reaction pressure of 300 pounds per square inch absolute and expansion ratio of 20.4. On basis of maximum specific impulse alone, five fuels had the following order for any given oxidant: liquid hydrogen, hydrazine, liquid ammonia, and either hydrazine hydrate or hydroxylamine. Three oxidants with a given fuel had the following order: liquid ozone, liquid oxygen, and 100-percent hydrogen peroxide.

Method and apparatus for providing a precise amount of gas at a precise humidity

DOEpatents

Hallman, Jr., Russell L.; Truett, James C.

2001-02-06

A fluid transfer system includes a permeable fluid carrier, a constant temperature source of a first fluid, and a constant pressure source of a second fluid. The fluid carrier has a length, an inlet end, and an outlet end. The constant pressure source connects to the inlet end and communicates the second fluid into the fluid carrier, and the constant temperature source surrounds a least of portion of the length. A mixture of the first fluid and the second fluid exits via the outlet end A method of making a mixture of two fluids is also disclosed.

Combustion of bark and wood waste in the fluidized bed boiler

NASA Astrophysics Data System (ADS)

Pleshanov, K. A.; Ionkin, I. L.; Roslyakov, P. V.; Maslov, R. S.; Ragutkin, A. V.; Kondrat'eva, O. E.

2016-11-01

In the Energy Development Strategy of Russia for the Period until 2035, special attention is paid to increased use of local fuel kinds—one of which is biofuel, in particular, bark and wood waste (BWW)— whose application at thermal power plants in Russia has been not developed due to the lack of appropriate technologies mastered by domestic energy mechanical engineering. The article describes the experience of BWW combustion in fluidized bed boilers installed on the energy objects of northern European countries. Based on this, reference points were defined (it is the section of boiler air-gas path where initially the approximate temperatures are set), making it possible to carry out a thermal design of a boiler and ensure its operation reliability. Permissible gas temperature at the furnace outlet at BWW combustion amounted to 950-1000°C. Exit gas temperature, depending on the implementation of special measures on protection of air heater from corrosion, amounted to 140-190°C. Recommended hot air temperature is within the range of 200-250°C. Recommendations for determining the boiler furnace dimensions are presented. Based on the presented reference temperatures in the main reference points, the thermal design of hot water boiler of KV-F-116-150 type with 116 MW capacity was carried out. The analysis of the results and comparison of designed boiler characteristics with operating energy boilers, in which a fuel is burned in a fluidized bed, were carried out. It is shown that, with increasing the boiler capacity, the ratio of its heating power Q to the crosssectional area of furnace chamber F rises. For power-generating boiler of thermal capacity of 100 MW, the ratio is within 1.8-2.2MW/m2. The boiler efficiency exceeds 90% in the range of changes of exit gas temperature typical for such equipment.

Fundamental Mixing and Combustion Experiments for Propelled Hypersonic Flight. Chaper 7

NASA Technical Reports Server (NTRS)

Diskin, G. S.; Danehy, P. M.; Drummond, J. P.; Cutler, A. D.

2002-01-01

The first experiment is a study of a coaxial jet discharging into stagnant laboratory air, with center jet of a mixture of 5% oxygen and 95% helium by volume and coflow jet of air. The exit flow pressure of both center-jet and coflow nozzles is 1 atmosphere. The presence of oxygen in the center jet is to allow the use of an oxygen flow-tagging technique (RELIEF4) to obtain non-intrusive velocity measurements. Both jets are nominally Mach 1.8, but, because of the greater speed of sound, the center jet velocity is more than twice that of the coflow. The mixing layer which forms between the center jet and the coflow near the nozzle exit is compressible, with a calculated convective Mach number of approximately 0.7. This geometry has several advantages: The streamwise development of the flow is generally dominated by turbulent stresses (rather than pressure forces), and thus calculations are sensitive to turbulence modeling. It includes features present in supersonic combustors, including a compressible mixing layer near the nozzle exit and a light-gas/air plume downstream. Since it is a free jet, it provides easy access for both optical instrumentation and probes. Since it is axisymmetric, it requires fewer experimental measurements to fully characterize, and calculations can be performed with more modest computer resources. However, weak shock waves formed at the nozzle exit strengthen and turn normal as they approach the axis, complicating the flow. Care is thus taken in the design of the facility to provide as near as possible to 1-D flow at the exit of both center and coflow nozzles, and to minimize the strength of waves generated at the nozzle exit. Results from this experiment are compared to CFD solutions obtained by VULCAN, a previously developed code used in engine analysis. The second experiment is a study of a supersonic combustor consisting of a diverging duct with single downstream-angled wall injector. Thus, the geometry is relatively simple and large regions of subsonic recirculating flow are avoided. The nominal entrance Mach number is 2 and the enthalpy of the test gas (hot air "simulant") is nominally that of Mach 7 flight. It was believed, on the basis of calculations performed that this would produce mixing-limited flow, that is to say, one for which chemical reaction to equilibrium proceeds at a much greater rate than mixing. It later proved that this was not the case. The primary experimental technique employed is coherent anti-Stokes Raman spectroscopy, known by its acronym CARS. The species probed is molecular nitrogen and the quantity measured is temperature. Intrusive probes, such as Pitot, total temperature, hot-wire, etc., are not used due to access difficulty and high heat flux in the combustor, and because they may alter the flow. CARS has several advantages over other optical methods. It is a relatively mature and well-understood technique. Signal levels are relatively high and the signal is in the form of a coherent (laser) beam that can be collected through small windows. Incoherent (non-CARS) interferences are rejected by spatial filtering.

Signatures of a conical intersection in photofragment distributions and absorption spectra: Photodissociation in the Hartley band of ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Picconi, David; Grebenshchikov, Sergy Yu., E-mail: Sergy.Grebenshchikov@ch.tum.de

Photodissociation of ozone in the near UV is studied quantum mechanically in two excited electronic states coupled at a conical intersection located outside the Franck-Condon zone. The calculations, performed using recent ab initio PESs, provide an accurate description of the photodissociation dynamics across the Hartley/Huggins absorption bands. The observed photofragment distributions are reproduced in the two electronic dissociation channels. The room temperature absorption spectrum, constructed as a Boltzmann average of many absorption spectra of rotationally excited parent ozone, agrees with experiment in terms of widths and intensities of diffuse structures. The exit channel conical intersection contributes to the coherent broadeningmore » of the absorption spectrum and directly affects the product vibrational and translational distributions. The photon energy dependences of these distributions are strikingly different for fragments created along the adiabatic and the diabatic paths through the intersection. They can be used to reverse engineer the most probable geometry of the non-adiabatic transition. The angular distributions, quantified in terms of the anisotropy parameter β, are substantially different in the two channels due to a strong anticorrelation between β and the rotational angular momentum of the fragment O{sub 2}.« less

MATE (Materials for Advanced Turbine Engines) Program, Project 3. Volume 2: Design, fabrication and evaluation of an oxide dispersion strengthened sheet alloy combustor liner

NASA Technical Reports Server (NTRS)

Bose, S.; Sheffler, K. D.

1988-01-01

The suitability of wrought oxide dispersion strengthened (ODS) superalloy sheet for gas turbine engine combustor applications was evaluated. Two yttria (Y2O3) dispersion strengthened alloys were evaluated; Incoloy MA956 and Haynes Development Alloy (HDA) 8077 (NiCrAl base). Preliminary tests showed both alloys to be potentially viable combustor materials, with neither alloy exhibiting a significant advantage over the other. MA956 was selected as the final alloy based on manufacturing reproducibility for evaluation as a burner liner. A hybrid PW2037 inner burner liner containing MA956 and Hastelloy X components and using a louvered configuration was designed and constructed. The louvered configuration was chosen because of field experience and compatibility with the bill of material PW2037 design. The simulated flight cycle for the ground based engine tests consisted of 4.5 min idle, 1.5 min takeoff and intermediate conditions in a PW2037 engine with average uncorrected combustor exit temperature of 1527 C. Post test evaluation consisting of visual observations and fluorescent penetrant inspections was conducted after 500 cycles of testing. No loss of integrity in the burner liner was shown.

Do spouses coordinate their work exits? A combined survey and register analysis from Norway.

PubMed

Syse, Astri; Solem, Per Erik; Ugreninov, Elisabeth; Mykletun, Reidar; Furunes, Trude

2014-09-01

Research on spouses' joint work exits is scarce, although household factors such as spouses' work status, marital quality, and caregiving burdens are likely to affect seniors' work engagement. We therefore examine whether the work exit probability of one spouse affects that of the other. Discrete-time hazard regression analyses of survey data linked to later registry information including all gainfully employed married respondents aged 50-74 with a working spouse (N = 1,764) were used to assess subsequent work exits. A spouse's work exit is a strong predictor of a respondent's work exit (hazard ratio 3.1, 95% confidence interval [2.5, 4.0]). Educational attainment, poor marital quality, and spouses' health and care needs do not predict work exits. Surprisingly, no gender differences are observed. Research on larger survey samples to distinguish different work exit routes and reasons for spouses' joint work exits appears warranted. To account for cultural and welfare state characteristics, cross-national studies ought to be undertaken. © The Author(s) 2013.

Cause and cure for high volatile coal and corrosive gases at TXI, Midlothian Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shahid, A.; Bottelberghe, B.; Crowther, J.

2007-07-01

The plant has raw materials which are high in pyritic sulfur. The coal mill uses the preheater exhaust gases, which have elevated amounts of SO{sub 2}. The coal being used is highly volatile. Therefore the coal mill bag filter had few occurrences of smoldered bags causing potentially unsafe conditions. This problem was solved by implementing some operational changes like reducing the mill exit temperature based on dewatering curve of coal and making the system more inert. To achieve this water had to be added into the system. When the mill exit temperature was reduced, the operating temperatures were below themore » sulfuric and hydrochloric acid dew points. Because of this corrosive acid stream in the gas flow, the bag filter started corroding. En route to solving these issues, the plant neutralized the acid by adding the raw meal dust and changing the bag filter into a stainless steel construction. Furthermore, the requirement to spray water in the system was removed by adding a heat exchanger to the coal mill inlet. Also, there were some design changes made to the coal mill bag filter, which helped in stable operation and extended bag life in the bag filter. This paper discusses these issues and how these problems were solved. This paper would be of beneficial use for other plants, which have to deal with high volatile coal and highly corrosive gases.« less

Gap Flows through Idealized Topography. Part I: Forcing by Large-Scale Winds in the Nonrotating Limit.

NASA Astrophysics Data System (ADS)

Gabersek, Sasa.; Durran, Dale R.

2004-12-01

Gap winds produced by a uniform airstream flowing over an isolated flat-top ridge cut by a straight narrow gap are investigated by numerical simulation. On the scale of the entire barrier, the proportion of the oncoming flow that passes through the gap is relatively independent of the nondimensional mountain height , even over that range of for which there is the previously documented transition from a “flow over the ridge” regime to a “flow around” regime.The kinematics and dynamics of the gap flow itself were investigated by examining mass and momentum budgets for control volumes at the entrance, central, and exit regions of the gap. These analyses suggest three basic behaviors: the linear regime (small ) in which there is essentially no enhancement of the gap flow; the mountain wave regime ( 1.5) in which vertical mass and momentum fluxes play a crucial role in creating very strong winds near the exit of the gap; and the upstream-blocking regime ( 5) in which lateral convergence generates the strongest winds near the entrance of the gap.Trajectory analysis of the flow in the strongest events, the mountain wave events, confirms the importance of net subsidence in creating high wind speeds. Neglect of vertical motion in applications of Bernoulli's equation to gap flows is shown to lead to unreasonable wind speed predictions whenever the temperature at the gap exit exceeds that at the gap entrance. The distribution of the Bernoulli function on an isentropic surface shows a correspondence between regions of high Bernoulli function and high wind speeds in the gap-exit jet similar to that previously documented for shallow-water flow.

Measurement of average density and relative volumes in a dispersed two-phase fluid

DOEpatents

Sreepada, Sastry R.; Rippel, Robert R.

1992-01-01

An apparatus and a method are disclosed for measuring the average density and relative volumes in an essentially transparent, dispersed two-phase fluid. A laser beam with a diameter no greater than 1% of the diameter of the bubbles, droplets, or particles of the dispersed phase is directed onto a diffraction grating. A single-order component of the diffracted beam is directed through the two-phase fluid and its refraction is measured. Preferably, the refracted beam exiting the fluid is incident upon a optical filter with linearly varing optical density and the intensity of the filtered beam is measured. The invention can be combined with other laser-based measurement systems, e.g., laser doppler anemometry.

Feasibility evaluation of the monolithic braided ablative nozzle

NASA Astrophysics Data System (ADS)

Director, Mark N.; McPherson, Douglass J., Sr.

1992-02-01

The feasibility of the monolithic braided ablative nozzle was evaluated as part of an independent research and development (IR&D) program complementary to the National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC) Low-Cost, High-Reliability Case, Insulation and Nozzle for Large Solid Rocket Motors (LOCCIN) Program. The monolithic braided ablative nozzle is a new concept that utilizes a continuous, ablative, monolithic flame surface that extends from the nozzle entrance, through the throat, to the exit plane. The flame surface is fabricated using a Through-the-Thickness braided carbon-fiber preform, which is impregnated with a phenolic or phenolic-like resin. During operation, the braided-carbon fiber/resin material ablates, leaving the structural backside at temperatures which are sufficiently low to preclude the need for any additional insulative materials. The monolithic braided nozzle derives its potential for low life cycle cost through the use of automated processing, one-component fabrication, low material scrap, low process scrap, inexpensive raw materials, and simplified case attachment. It also has the potential for high reliability because its construction prevents delamination, has no nozzle bondlines or leak paths along the flame surface, is amenable to simplified analysis, and is readily inspectable. In addition, the braided construction has inherent toughness and is damage-tolerant. Two static-firing tests were conducted using subscale, 1.8 - 2.0-inch throat diameter, hardware. Tests were approximately 15 seconds in duration, using a conventional 18 percent aluminum/ammonium perchlorate propellant. The first of these tests evaluated the braided ablative as an integral backside insulator and exit cone; the second test evaluated the monolithic braided ablative as an integral entrance/throat/exit cone nozzle. Both tests met their objectives. Radial ablation rates at the throat were as predicted, approximately 0.017 in/sec; these rates are comparable to those for tapewrapped carbon phenolic materials. The maximum temperature rise on the outside surface occurred one inch from the nozzle exit plane and was less than 50 F at the end of the test. Further development for this concept is scheduled as part of phase 2 on the NASA/MSFC LOCCIN Program. During this effort, the nozzle materials, architecture, and processing will be optimized and tested in nozzles with 3- and 10-inch diameter throats. Further, a design and manufacturing plan for a full-scale, 20-inch-diameter throat, nozzle will be developed.

Performance Characteristics of Flush and Shielded Auxiliary Exits at Mach Numbers of 1.5 to 2.0

NASA Technical Reports Server (NTRS)

Abdalla, Kaleel L.

1959-01-01

The performance characteristics of several flush and shielded auxiliary exits were investigated at Mach numbers of 1.5 to 2.0, and jet pressure ratios from jet off to 10. The results indicate that the shielded configurations produced better overall performance than the corresponding flush exits over the Mach-number and pressure-ratio ranges investigated. Furthermore, the full-length shielded exit was highest in performance of all the configurations. The flat-exit nozzle block provided considerably improved performance compared with the curved-exit nozzle block.

Can favourable psychosocial working conditions in midlife moderate the risk of work exit for chronically ill workers? A 20-year follow-up of the Whitehall II study.

PubMed

Fleischmann, Maria; Carr, Ewan; Stansfeld, Stephen A; Xue, Baowen; Head, Jenny

2018-03-01

To investigate if favourable psychosocial working conditions can reduce the risk of work exit and specifically for workers with chronic disease. Men and women (32%) aged 35-55, working and having no chronic disease at baseline of the Whitehall II study of London-based civil servants were selected (n=9040). We observed participants' exit from work through retirement, health-related exit and unemployment, new diagnosis of chronic disease (ie, coronary heart disease, diabetes, stroke and cancer) and their psychosocial working conditions in midlife. Using cause-specific Cox models, we examined the association of chronic disease and favourable psychosocial working conditions and their interaction, with the three types of work exit. We adjusted for gender, occupational grade, educational level, remaining in civil service, spouse's employment status and mental health. Chronic disease significantly increased the risk of any type of work exit (HR 1.27) and specifically the risk of health-related exit (HR 2.42). High skill discretion in midlife reduced the risk of any type of work exit (HR 0.90), retirement (HR 0.91) and health-related exit (HR 0.68). High work social support in midlife decreased the risk of health-related exit (HR 0.79) and unemployment (HR 0.71). Favourable psychosocial working conditions in midlife did not attenuate the association between chronic disease and work exit significantly. The chronically ill have increased risks of work exit, especially through health-related exit routes. Chronic disease is an obstacle to extended working lives. Favourable working conditions directly relate to reduced risks of work exit. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Peritonitis and exit-site infection in pediatric automated peritoneal dialysis.

PubMed

Chiu, Man-Chun; Tong, Pak-Chiu; Lai, Wai-Ming; Lau, Shing-Chi

2008-06-01

We reviewed 30 patients in an automated peritoneal dialysis (APD) program from 2002 to 2006 for peritonitis. Patients were 11.6 +/- 5.5 years old at initiation of peritoneal dialysis (PD) and had a total of 976 PD months. The overall peritonitis rate was 1 episode in 54.2 patient-months, for a rate of 0.22 episode annually. The rate was considered low, which other than being an APD program, may be attributed to adherence to guidelines and in-charge nurse policy. A total of 17 episodes of peritonitis were identified in 9 patients, and the distribution of patient-specific peritonitis incidence appeared bimodal: 87% patients had no or only 1 episode of peritonitis, and 4 patients accounted for 12 episodes, with an average peritonitis rate of 1.0 annually. Causative organisms included Staphylococcus aureus, coagulase-negative Staphylococcus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa, enterococci, alpha-hemolytic Streptococcus. Five episodes had concurrent exit-site infection with the same organism. During the same period in these 30 patients, 40 episodes of exit-site infection (ESI) were recorded in 23 patients. The overall ESI rate was 1 episode in 24.4 PD months. S. aureus and Pseudomonas aeruginosa were the two most common pathogens, accounting for 70% of the infections. Nasal carriage of MRSA was found in 4 patients, and MRSA ESIs in 2. The ESI rate was not low as that observed in peritonitis, which may be attributed to the humid climate.

HIGH ENERGY RATE EXTRUSION OF URANIUM

DOEpatents

Lewis, L.

1963-07-23

A method of extruding uranium at a high energy rate is described. Conditions during the extrusion are such that the temperature of the metal during extrusion reaches a point above the normal alpha to beta transition, but the metal nevertheless remains in the alpha phase in accordance with the Clausius- Clapeyron equation. Upon exiting from the die, the metal automatically enters the beta phase, after which the metal is permitted to cool. (AEC)

Evaluation of System Architectures for the Army Aviation Ground Power Unit

DTIC Science & Technology

2014-12-01

this state of operation induces wear that reduces pump life. Variable capacity control methods using a constant displacement pump are drive speed...options for use with constant displacement pumps, the fluid or magnetic coupling devices are the most attractive. Variable frequency control cannot...compressor prior to the combustor. The cmTent system turbine exhaust temperature controls to 1250°F, much higher than the compressor exit

Design and preliminary results of a semitranspiration cooled (Lamilloy) liner for a high-pressure high-temperature combustor

NASA Technical Reports Server (NTRS)

Wear, J. D.; Trout, A. M.; Smith, J. M.; Jones, R. E.

1978-01-01

A Lamilloy combustor liner was designed, fabricated and tested in a combustor at pressures up to 8 atmospheres. The liner was fabricated of a three layer Lamilloy structure and designed to replace a conventional step louver liner. The liner is to be used in a combustor that provides hot gases to a turbine cooling test facility at pressures up to 40 atmospheres. The Lamilloy liner was tested extensively at lower pressures and demonstrated lower metal temperatures than the conventional liner, while at the same time requiring about 40 percent less cooling air flow. Tests conducted at combustor exit temperatures in excess of 2200 K have not indicated any cooling or durability problems with the Lamilloy linear.

Performance of a high-work low aspect ration turbine tested with a realistic inlet radial temperature profile

NASA Technical Reports Server (NTRS)

Stabe, R. G.; Whitney, W. J.; Moffitt, T. P.

1984-01-01

Experimental results are presented for a 0.767 scale model of the first stage of a two-stage turbine designed for a high by-pass ratio engine. The turbine was tested with both uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The inlet temperature profile was essentially mixed-out in the rotor. There was also substantial underturning of the exit flow at the mean diameter. Both of these effects were attributed to strong secondary flows in the rotor blading. There were no significant differences in the stage performance with either inlet condition when differences in tip clearance were considered. Performance was very close to design intent in both cases.

Estimated Performance of Radial-Flow Exit Nozzles for Air in Chemical Equilibrium

NASA Technical Reports Server (NTRS)

Englert, Gerald W.; Kochendorfer, Fred D.

1959-01-01

The thrust, boundary-layer, and heat-transfer characteristics were computed for nozzles having radial flow in the divergent part. The working medium was air in chemical equilibrium, and the boundary layer was assumed to be all turbulent. Stagnation pressure was varied from 1 to 32 atmospheres, stagnation temperature from 1000 to 6000 R, and wall temperature from 1000 to 3000 R. Design pressure ratio was varied from 5 to 320, and operating pressure ratio was varied from 0.25 to 8 times the design pressure ratio. Results were generalized independent of divergence angle and were also generalized independent of stagnation pressure in the temperature range of 1000 to 3000 R. A means of determining the aerodynamically optimum wall angle is provided.

Infrared Low Temperature Turbine Vane Rough Surface Heat Transfer Measurements

NASA Technical Reports Server (NTRS)

Boyle, R. J.; Spuckler, C. M.; Lucci, B. L.; Camperchioli, W. P.

2000-01-01

Turbine vane heat transfer distributions obtained using an infrared camera technique are described. Infrared thermography was used because noncontact surface temperature measurements were desired. Surface temperatures were 80 C or less. Tests were conducted in a three vane linear cascade, with inlet pressures between 0.14 and 1.02 atm., and exit Mach numbers of 0.3, 0.7, and 0.9, for turbulence intensities of approximately 1 and 10%. Measurements were taken on the vane suction side, and on the pressure side leading edge region. The designs for both the vane and test facility are discussed. The approach used to account for conduction within the vane is described. Midspan heat transfer distributions are given for the range of test conditions.

Method for determining hydrogen mobility as a function of temperature in superconducting niobium cavities

DOEpatents

May, Robert [Virginia Beach, VA

2008-03-11

A method for determining the mobility of hydrogen as a function of temperature in superconducting niobium cavities comprising: 1) heating a cavity under test to remove free hydrogen; 2) introducing hydrogen-3 gas into the cavity; 3) cooling the cavity to allow absorption of hydrogen-3; and 4) measuring the amount of hydrogen-3 by: a) cooling the cavity to about 4.degree. K while flowing a known and regulated amount of inert carrier gas such as argon or helium into the cavity; b) allowing the cavity to warm at a stable rate from 4.degree. K to room temperature as it leaves the chamber; and c) directing the exit gas to an ion chamber radiation detector.

A generalized one-dimensional computer code for turbomachinery cooling passage flow calculations

NASA Technical Reports Server (NTRS)

Kumar, Ganesh N.; Roelke, Richard J.; Meitner, Peter L.

1989-01-01

A generalized one-dimensional computer code for analyzing the flow and heat transfer in the turbomachinery cooling passages was developed. This code is capable of handling rotating cooling passages with turbulators, 180 degree turns, pin fins, finned passages, by-pass flows, tip cap impingement flows, and flow branching. The code is an extension of a one-dimensional code developed by P. Meitner. In the subject code, correlations for both heat transfer coefficient and pressure loss computations were developed to model each of the above mentioned type of coolant passages. The code has the capability of independently computing the friction factor and heat transfer coefficient on each side of a rectangular passage. Either the mass flow at the inlet to the channel or the exit plane pressure can be specified. For a specified inlet total temperature, inlet total pressure, and exit static pressure, the code computers the flow rates through the main branch and the subbranches, flow through tip cap for impingement cooling, in addition to computing the coolant pressure, temperature, and heat transfer coefficient distribution in each coolant flow branch. Predictions from the subject code for both nonrotating and rotating passages agree well with experimental data. The code was used to analyze the cooling passage of a research cooled radial rotor.

Heat Transfer Computations of Internal Duct Flows With Combined Hydraulic and Thermal Developing Length

NASA Technical Reports Server (NTRS)

Wang, C. R.; Towne, C. E.; Hippensteele, S. A.; Poinsatte, P. E.

1997-01-01

This study investigated the Navier-Stokes computations of the surface heat transfer coefficients of a transition duct flow. A transition duct from an axisymmetric cross section to a non-axisymmetric cross section, is usually used to connect the turbine exit to the nozzle. As the gas turbine inlet temperature increases, the transition duct is subjected to the high temperature at the gas turbine exit. The transition duct flow has combined development of hydraulic and thermal entry length. The design of the transition duct required accurate surface heat transfer coefficients. The Navier-Stokes computational method could be used to predict the surface heat transfer coefficients of a transition duct flow. The Proteus three-dimensional Navier-Stokes numerical computational code was used in this study. The code was first studied for the computations of the turbulent developing flow properties within a circular duct and a square duct. The code was then used to compute the turbulent flow properties of a transition duct flow. The computational results of the surface pressure, the skin friction factor, and the surface heat transfer coefficient were described and compared with their values obtained from theoretical analyses or experiments. The comparison showed that the Navier-Stokes computation could predict approximately the surface heat transfer coefficients of a transition duct flow.

Measurement of Vibrational Non-Equilibrium in a Supersonic Freestream Using Dual-Pump CARS

NASA Technical Reports Server (NTRS)

Cutler, Andrew D.; Magnotti, Gaetano; Cantu, Luca M. L.; Gallo, Emanuela C. A.; Danehy, Paul M.; Burle, Rob; Rockwell, Robert; Goyne, Christopher; McDaniel, James

2012-01-01

Measurements have been conducted at the University of Virginia Supersonic Combustion Facility of the flow in a constant area duct downstream of a Mach 2 nozzle, where the airflow has first been heated to approximately 1200 K. Dual-pump CARS was used to acquire rotational and vibrational temperatures of N2 and O2 at two planes in the duct at different downstream distances from the nozzle exit. Wall static pressures in the nozzle are also reported. With a flow of clean air, the vibrational temperature of N2 freezes at close to the heater stagnation temperature, while the O2 vibrational temperature is about 1000 K. The results are well predicted by computational fluid mechanics models employing separate "lumped" vibrational and translational/rotational temperatures. Experimental results are also reported for a few percent steam addition to the air and the effect of the steam is to bring the flow to thermal equilibrium.

Adolescents Exiting Homelessness Over Two Years: The Risk Amplification and Abatement Model

PubMed Central

Milburn, Norweeta G.; Rice, Eric; Rotheram-Borus, Mary Jane; Mallett, Shelley; Rosenthal, Doreen; Batterham, Phillip; May, Susanne J.; Witkin, Andrea; Duan, Naihua

2014-01-01

The Risk Amplification and Abatement Model (RAAM), demonstrates that negative contact with socializing agents amplify risk, while positive contact abates risk for homeless adolescents. To test this model, the likelihood of exiting homelessness and returning to familial housing at 2 years and stably exiting over time are examined with longitudinal data collected from 183 newly homeless adolescents followed over 2 years in Los Angeles, CA. In support of RAAM, unadjusted odds of exiting at 2 years and stably exiting over2 years revealed that engagement with pro-social peers, maternal social support, and continued school attendance all promoted exiting behaviors. Simultaneously, exposure to family violence and reliance on shelter services discouraged stably exiting behaviors. Implications for family-based interventions are proposed. PMID:25067896

SU-F-T-229: A Novel Method for EPID-Based In-Vivo Exit Dose Verification for Intensity Modulated Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Z; Wang, J; Peng, J

Purpose: Electronic portal imaging device (EPID) can be used to acquire a two-dimensional exit dose distribution during treatment delivery, thus allowing the in-vivo verification of the dose delivery through a comparison of measured portal images to predicted portal dose images (PDI). The aim of this study was to present a novel method to easily and accurately predict PDI, and to establish an EPID-based in-vivo dose verification method during IMRT treatments. Methods: We developed a model to determine the predicted portal dose at the same plane of the EPID detector location. The Varian EPID (aS1000) positions at 150cm source-to-detector-distance (SDD), andmore » can be used to acquire in-vivo exit dose using Portal Dosimetry (PD) function. Our model was generated to make an equivalent water thickness represent the buildup plate of EPID. The exit dose at extend SDD plane with patient CT data in the beam can be calculated as the predicted PDI in the treatment planning system (TPS). After that, the PDI was converted to the fluence at SDD of 150cm using the inverse square law coded in MATLAB. Five head-and-neck and prostate IMRT patient plans contain 32 fields were investigated to evaluate the feasibility of this new method. The measured EPID image was compared with PDI using the gamma analysis. Results: The average results for cumulative dose comparison were 81.9% and 91.6% for 3%, 3mm and 4%, 4mm gamma criteria, respectively. Results indicate that the patient transit dosimetry predicted algorithm compares well with EPID measured PD doses for test situations. Conclusion: Our new method can be used as an easy and feasible tool for online EPID-based in-vivo dose delivery verification for IMRT treatments. It can be implemented for fast detecting those obvious treatment delivery errors for individual field and patient quality assurance.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Breault, Ronald W.; Monazam, Esmail R.; Shadle, Lawrence J.

Riser hydrodynamics are a function of the flow rates of gas and solids as well as the exit geometry, particularly when operated above the upper transport velocity. This work compares the exit voidage for multiple geometries and two different solids: Geldart group A glass beads and Geldart group B coke. Geometries were changed by modifying the volume of an abrupt T-shaped exit above the lateral riser exit. This was accomplished by positioning a plunger at various heights above the exit from zero to 0.38 m. A dimensionless expression used to predict smooth exit voidage was modified to account for themore » effect of the depth of the blind-T. The new correlation contains the solids-gas load ratio, solids-to-gas density ratio, bed-to-particle diameter ratio, gas Reynolds Number, as well as a term for the exit geometry. This study also found that there was a minimum riser roof height above the blind-T exit beyond which the riser exit voidage was not affected by the exit geometry. A correlation for this minimum riser roof height has also been developed in this study. This study covered riser superficial gas velocities of 4.35 to 7.7 m/s and solids circulation rates of 1.3 to 11.5 kg/s.« less

Influence of drill helical direction on exit damage development in drilling carbon fiber reinforced plastic

NASA Astrophysics Data System (ADS)

Bai, Y.; Jia, Z. Y.; Wang, F. J.; Fu, R.; Guo, H. B.; Cheng, D.; Zhang, B. Y.

2017-06-01

Drilling is inevitable for CFRP components’ assembling process in the aviation industry. The exit damage frequently occurs and affects the load carrying capacity of components. Consequently, it is of great urgency to enhance drilling exit quality on CFRP components. The article aims to guide the reasonable choice of drill helical direction and effectively reduce exit damage. Exit observation experiments are carried out with left-hand helical, right-hand helical and straight one-shot drill drilling T800S CFRP laminates separately. The development rules of exit damage and delamination factor curves are obtained. Combined with loading conditions and fracture modes of push-out burrs, and thrust force curves, the influence of drill helical direction on exit damage development is derived. It is found that the main fracture modes for left-hand helical, right-hand helical, and straight one-shot drill are mode I, extrusive fracture, mode III respectively. Among them, mode III has the least effect on exit damage development. Meanwhile, the changing rate of thrust force is relative slow for right-hand helical and straight one-shot drill in the thrust force increasing phase of stage II, which is disadvantaged for exit damage development. Therefore, straight one-shot drill’s exit quality is the best.

Design and numeric evaluation of a novel axial-flow left ventricular assist device.

PubMed

Toptop, Koral; Kadipasaoglu, Kamuran A

2013-01-01

Virtual design characteristics and performance of the first Turkish axial-flow left ventricular assist device (LVAD) are presented, with emphasis on rotor geometry. The patented rotor design includes a central flow channel carved inside the main block, which carries permanent magnets. A concentric rotor-stator gap minimizes the distance between respective magnets, improving electromagnetic efficiency and creating a second blood pathway. Dual sets of three helical blades, placed on the shaft and external surface of the rotor block, ensure unidirectionality. Hemodynamic performance was tested with computational fluid dynamics (CFD); and rotor-blade geometry was optimized, to maximize overall efficiency d and minimize backflow and wall shear stresses. For a shaft radius of 4.5 mm, rotor blade height of 2.5 mm, and blade inlet and exit metal angles of 67° and 32°, pump operation at the nominal head-flow combination (5 L/min and 100.4 mm Hg) was achieved at a rotor speed of 10,313 rpm. At the nominal point, backflow as percent of total flow was 7.29 and 29.87% at rotor inlet and exit, respectively; overall hydraulic efficiency reached 21.59%; and maximum area-averaged shroud shear was 520 Pa. Overall efficiency peaked at 24.07% for a pump flow of 6.90 L/min, and averaged at 22.57% within the flow range of 4-8 L/min. We concluded that the design satisfies initial rotor design criteria, and that continued studies with diffuser optimization and transient flow analysis are warranted.

Shaping the future medical workforce: take care with selection tools.

PubMed

Poole, Phillippa; Shulruf, Boaz

2013-12-01

Medical school selection is a first step in developing a general practice workforce. To determine the relationship between medical school selection scores and intention to pursue a career in general practice. A longitudinal cohort study of students selected in 2006 and 2007 for The University of Auckland medical programme, who completed an exit survey on career intentions. Students are ranked for selection into year 2 of a six-year programme by combining grade point average from prior university achievement (60%), interview (25%) and Undergraduate Medicine and Health Sciences Admission Test (UMAT) scores (15%). The main outcome measure was level of interest in general practice at exit. Logistic regression assessed whether any demographic variables or admission scores predicted a 'strong' interest in general practice. None of interview scores, grade point average, age, gender, or entry pathway predicted a 'strong' interest in general practice. Only UMAT scores differentiated between those with a 'strong' interest versus those with 'some' or 'no' interest, but in an inverse fashion. The best predictor of a 'strong' interest in general practice was a low UMAT score of between 45 and 55 on all three UMAT sections (OR 3.37, p=0.020). Yet, the academic scores at entry of students with these UMAT scores were not lower than those of their classmates. Setting inappropriately high cut-points for medical school selection may exclude applicants with a propensity for general practice. These findings support the use of a wider lens through which to view medical school selection tools.

Use of an approximate similarity principle for the thermal scaling of a full-scale thrust augmenting ejector

NASA Technical Reports Server (NTRS)

Barankiewicz, Wendy S.; Perusek, Gail P.; Ibrahim, Mounir B.

1992-01-01

Full temperature ejector model simulations are expensive, and difficult to implement experimentally. If an approximate similarity principle could be established, properly chosen performance parameters should be similar for both hot and cold flow tests if the initial Mach number and total pressures of the flow field are held constant. Existing ejector data is used to explore the utility of one particular similarity principle; the Munk and Prim similarity principle for isentropic flows. Static performance test data for a full-scale thrust augmenting ejector are analyzed for primary flow temperatures up to 1560 R. At different primary temperatures, exit pressure contours are compared for similarity. A nondimensional flow parameter is then used to eliminate primary nozzle temperature dependence and verify similarity between the hot and cold flow experiments.

Use of an approximate similarity principle for the thermal scaling of a full-scale thrust augmenting ejector

NASA Technical Reports Server (NTRS)

Barankiewicz, Wendy; Perusek, Gail P.; Ibrahim, Mounir

1992-01-01

Full temperature ejector model simulations are expensive, and difficult to implement experimentally. If an approximate similarity principle could be established, properly chosen performance parameters should be similar for both hot and cold flow tests if the initial Mach number and total pressures of the flow field are held constant. Existing ejector data is used to explore the utility of one particular similarity principle; the Munk and Prim similarity principle for isentropic flows. Static performance test data for a full-scale thrust augmenting ejector are analyzed for primary flow temperatures up to 1560 R. At different primary temperatures, exit pressure contours are compared for similarity. A nondimensional flow paramenter is then used to eliminate primary nozzle temperature dependence and verify similarity between the hot and cold flow experiments.

Large Eddy Simulation in a Channel with Exit Boundary Conditions

NASA Technical Reports Server (NTRS)

Cziesla, T.; Braun, H.; Biswas, G.; Mitra, N. K.

1996-01-01

The influence of the exit boundary conditions (vanishing first derivative of the velocity components and constant pressure) on the large eddy simulation of the fully developed turbulent channel flow has been investigated for equidistant and stretched grids at the channel exit. Results show that the chosen exit boundary conditions introduce some small disturbance which is mostly damped by the grid stretching. The difference between the fully developed turbulent channel flow obtained with LES with periodicity condition and the inlet and exit and the LES with fully developed flow at the inlet and the exit boundary condition is less than 10% for equidistant grids and less than 5% for the case grid stretching. The chosen boundary condition is of interest because it may be used in complex flows with backflow at exit.

Twitter-Delivered Behavioral Weight-Loss Interventions: A Pilot Series.

PubMed

Pagoto, Sherry L; Waring, Molly E; Schneider, Kristin L; Oleski, Jessica L; Olendzki, Effie; Hayes, Rashelle B; Appelhans, Bradley M; Whited, Matthew C; Busch, Andrew M; Lemon, Stephenie C

2015-10-23

Lifestyle interventions are efficacious at reducing risk for diabetes and cardiovascular disease but have not had a significant public health impact given high cost and patient and provider burden. Online social networks may reduce the burden of lifestyle interventions to the extent that they displace in-person visits and may enhance opportunities for social support for weight loss. We conducted an iterative series of pilot studies to evaluate the feasibility and acceptability of using online social networks to deliver a lifestyle intervention. In Study 1 (n=10), obese participants with depression received lifestyle counseling via 12 weekly group visits and a private group formed using the online social network, Twitter. Mean weight loss was 2.3 pounds (SD 7.7; range -19.2 to 8.2) or 1.2% (SD 3.6) of baseline weight. A total of 67% (6/9) of participants completing exit interviews found the support of the Twitter group at least somewhat useful. In Study 2 (n=11), participants were not depressed and were required to be regular users of social media. Participants lost, on average, 5.6 pounds (SD 6.3; range -15 to 0) or 3.0% (SD 3.4) of baseline weight, and 100% (9/9) completing exit interviews found the support of the Twitter group at least somewhat useful. To explore the feasibility of eliminating in-person visits, in Study 3 (n=12), we delivered a 12-week lifestyle intervention almost entirely via Twitter by limiting the number of group visits to one, while using the same inclusion criteria as that used in Study 2. Participants lost, on average, 5.4 pounds (SD 6.4; range -14.2 to 3.9) or 3.0% (SD 3.1) of baseline weight, and 90% (9/10) completing exit interviews found the support of the Twitter group at least somewhat useful. Findings revealed that a private Twitter weight-loss group was both feasible and acceptable for many patients, particularly among regular users of social media. Future research should evaluate the efficacy and cost-effectiveness of online social network-delivered lifestyle interventions relative to traditional modalities.

Twitter-Delivered Behavioral Weight-Loss Interventions: A Pilot Series

PubMed Central

Waring, Molly E; Schneider, Kristin L; Oleski, Jessica L; Olendzki, Effie; Hayes, Rashelle B; Appelhans, Bradley M; Whited, Matthew C; Busch, Andrew M; Lemon, Stephenie C

2015-01-01

Background Lifestyle interventions are efficacious at reducing risk for diabetes and cardiovascular disease but have not had a significant public health impact given high cost and patient and provider burden. Objective Online social networks may reduce the burden of lifestyle interventions to the extent that they displace in-person visits and may enhance opportunities for social support for weight loss. Methods We conducted an iterative series of pilot studies to evaluate the feasibility and acceptability of using online social networks to deliver a lifestyle intervention. Results In Study 1 (n=10), obese participants with depression received lifestyle counseling via 12 weekly group visits and a private group formed using the online social network, Twitter. Mean weight loss was 2.3 pounds (SD 7.7; range -19.2 to 8.2) or 1.2% (SD 3.6) of baseline weight. A total of 67% (6/9) of participants completing exit interviews found the support of the Twitter group at least somewhat useful. In Study 2 (n=11), participants were not depressed and were required to be regular users of social media. Participants lost, on average, 5.6 pounds (SD 6.3; range -15 to 0) or 3.0% (SD 3.4) of baseline weight, and 100% (9/9) completing exit interviews found the support of the Twitter group at least somewhat useful. To explore the feasibility of eliminating in-person visits, in Study 3 (n=12), we delivered a 12-week lifestyle intervention almost entirely via Twitter by limiting the number of group visits to one, while using the same inclusion criteria as that used in Study 2. Participants lost, on average, 5.4 pounds (SD 6.4; range -14.2 to 3.9) or 3.0% (SD 3.1) of baseline weight, and 90% (9/10) completing exit interviews found the support of the Twitter group at least somewhat useful. Findings revealed that a private Twitter weight-loss group was both feasible and acceptable for many patients, particularly among regular users of social media. Conclusions Future research should evaluate the efficacy and cost-effectiveness of online social network-delivered lifestyle interventions relative to traditional modalities. PMID:26500186

EOS Terra Terra Constellation Exit/Future Maneuver Plans Update

NASA Technical Reports Server (NTRS)

Mantziaras, Dimitrios

2016-01-01

This EOS Terra Constellation Exit/Future Maneuver Plans Update presentation will discuss brief history of Terra EOM work; lifetime fuel estimates; baseline vs. proposed plan origin; resultant exit orbit; baseline vs. proposed exit plan; long term orbit altitude; revised lifetime proposal and fallback options.

Effect of ambient temperature and humidity on emissions of an idling gas turbine

NASA Technical Reports Server (NTRS)

Kauffman, C. W.

1977-01-01

The effects of inlet pressure, temperature, and humidity on the oxides of nitrogen produced by an engine operating at takeoff power setting were investigated and numerous correction factors were formulated. The effect of ambient relative humidity on gas turbine idle emissions was ascertained. Experimentally, a nonvitiating combustor rig was employed to simulate changing combustor inlet conditions as generated by changing ambient conditions. Emissions measurements were made at the combustor exit. For carbon monoxide, a reaction kinetic scheme was applied within each zone of the combustor where initial species concentrations reflected not only local combustor characteristics but also changing ambient conditions.

Process for Polycrystalline film silicon growth

DOEpatents

Wang, Tihu; Ciszek, Theodore F.

2001-01-01

A process for depositing polycrystalline silicon on substrates, including foreign substrates, occurs in a chamber at about atmospheric pressure, wherein a temperature gradient is formed, and both the atmospheric pressure and the temperature gradient are maintained throughout the process. Formation of a vapor barrier within the chamber that precludes exit of the constituent chemicals, which include silicon, iodine, silicon diiodide, and silicon tetraiodide. The deposition occurs beneath the vapor barrier. One embodiment of the process also includes the use of a blanketing gas that precludes the entrance of oxygen or other impurities. The process is capable of repetition without the need to reset the deposition zone conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graceffa, R.; Burghammer, M.; Davies, R. J.

Using stroboscopic techniques, diffraction patterns of ballistic paraffin wax microdrops have been observed. The microdrops, generated by a high-temperature ink-jet system, travel through the 1 {mu}m synchrotron radiation beam with a speed of about 1.4 m/s. Diffraction patterns were recorded in flight by a charge couple device with a microchannel plate image intensifier stage, which was activated with the microdrop generation frequency of 1000 Hz during 2 {mu}s. The data show liquid microdrops with a constant temperature up to 8 mm from the ink-jet system capillary exit. The general technique could be adapted for studying fast structural processes, such asmore » protein conformational changes in aqueous microdrops.« less

Chemical Laser Systems: An Engineering Approach. Volume I. Chemical Laser Analysis Program

DTIC Science & Technology

1979-01-31

C* *CPCALC S040 CO CNO C V ALUES ASTORED IN RNITS Of NLUE-DOR JITKROLEoKJ AND TAPULATED *CPCALC OSSO CO BY TEMPERATURE (ROW) FROM 0 K TO 3000 K IM...KMOLEi P PRESSURE EPA) P DENSITY fKG/M31 REI REYNOLDS NUMBER T : TEMPERATURE CKI W i MASS FLOW RATE (KG/S] X a MOLAR FLOW RATE (KNOLE/S) REPEAYEO...200000E#67 PA REI * 21363AE*04 I ZISE0K10 JSSE0RI a .288884E- 1 KS/N3 Pie :174617f#01@ KG/N3 POINT 2 ’PRIMARY NOZZLE EXIT - CONDITIONS IASED ON THE

Using a Medical Intranet of Things System to Prevent Bed Falls in an Acute Care Hospital: A Pilot Study.

PubMed

Balaguera, Henri U; Wise, Diana; Ng, Chun Yin; Tso, Han-Wen; Chiang, Wan-Lin; Hutchinson, Aimee M; Galvin, Tracy; Hilborne, Lee; Hoffman, Cathy; Huang, Chi-Cheng; Wang, C Jason

2017-05-04

Hospitalized patients in the United States experience falls at a rate of 2.6 to 17.1 per 1000 patient-days, with the majority occurring when a patient is moving to, from, and around the bed. Each fall with injury costs an average of US $14,000. The aim was to conduct a technology evaluation, including feasibility, usability, and user experience, of a medical sensor-based Intranet of things (IoT) system in facilitating nursing response to bed exits in an acute care hospital. Patients 18 years and older with a Morse fall score of 45 or greater were recruited from a 35-bed medical-surgical ward in a 317-bed Massachusetts teaching hospital. Eligible patients were recruited between August 4, 2015 and July 31, 2016. Participants received a sensor pad placed between the top of their mattress and bed sheet. The sensor pad was positioned to monitor movement from patients' shoulders to their thighs. The SensableCare System was evaluated for monitoring patient movement and delivering timely alerts to nursing staff via mobile devices when there appeared to be a bed-exit attempt. Sensor pad data were collected automatically from the system. The primary outcomes included number of falls, time to turn off bed-exit alerts, and the number of attempted bed-exit events. Data on patient falls were collected by clinical research assistants and confirmed with the unit nurse manager. Explanatory variables included room locations (zones 1-3), day of the week, nursing shift, and Morse Fall Scale (ie, positive fall history, positive secondary diagnosis, positive ambulatory aid, weak impaired gait/transfer, positive IV/saline lock, mentally forgets limitations). We also assessed user experience via nurse focus groups. Qualitative data regarding staff interactions with the system were collected during two focus groups with 25 total nurses, each lasting approximately 1.5 hours. A total of 91 patients used the system for 234.0 patient-days and experienced no bed falls during the study period. On average, patients were assisted/returned to bed 46 seconds after the alert system was triggered. Response times were longer during the overnight nursing shift versus day shift (P=.005), but were independent of the patient's location on the unit. Focus groups revealed that nurses found the system integrated well into the clinical nursing workflow and the alerts were helpful in patient monitoring. A medical IoT system can be integrated into the existing nursing workflow and may reduce patient bed fall risk in acute care hospitals, a high priority but an elusive patient safety challenge. By using an alerting system that sends notifications directly to nurses' mobile devices, nurses can equally respond to unassisted bed-exit attempts wherever patients are located on the ward. Further study, including a fully powered randomized controlled trial, is needed to assess effectiveness across hospital settings. ©Henri U Balaguera, Diana Wise, Chun Yin Ng, Han-Wen Tso, Wan-Lin Chiang, Aimee M Hutchinson, Tracy Galvin, Lee Hilborne, Cathy Hoffman, Chi-Cheng Huang, C Jason Wang. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 04.05.2017.

Aircraft evacuations through type-III exits I : effects of seat placement at the exit.

DOT National Transportation Integrated Search

1995-07-01

Simulated emergency egress from Type III over-wing exits was studied to support regulatory action by the FAA. Passageway width and seat encroachment distance adjacent to the Type-III exit were the major variables of interest. : Methods. Two subject g...

29 CFR 1910.36 - Design and construction requirements for exit routes.

Code of Federal Regulations, 2012 CFR

2012-07-01

....36 Section 1910.36 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Exit Routes and Emergency Planning... of exit routes necessary for your workplace, consult NFPA 101-2000, Life Safety Code. (c) Exit...

Safety and operational performance evaluation of four types of exit ramps on Florida's freeways (final report).

DOT National Transportation Integrated Search

2010-12-01

This project mainly focuses on exit ramp performance analysis of safety and operations. In addition, issues of advance guide sign for exit ramp are also mentioned. : Safety analysis evaluates safety performances of different exit ramps used in Florid...

Simulation of preburner sprays, volumes 1 and 2

NASA Technical Reports Server (NTRS)

Hardalupas, Y.; Whitelaw, J. H.

1993-01-01

The present study considered characteristics of sprays under a variety of conditions. Control of these sprays is important as the spray details can control both rocket combustion stability and efficiency. Under the present study Imperial College considered the following: (1) Measurement of the size and rate of spread of the sprays produced by single coaxial airblast nozzles with axial gaseous stream. The local size, velocity, and flux characteristics for a wide range of gas and liquid flowrates were measured, and the results were correlated with the conditions of the spray at the nozzle exit. (2) Examination of the effect of the geometry of single coaxial airblast atomizers on spray characteristics. The gas and liquid tube diameters were varied over a range of values, the liquid tube recess was varied, and the shape of the exit of the gaseous jet was varied from straight to converging. (3) Quantification of the effect of swirl in the gaseous stream on the spray characteristics produced by single coaxial airblast nozzles. (4) Quantification of the effect of reatomization by impingement of the spray on a flat disc positioned around 200 mm from the nozzle exit. This models spray impingement on the turbopump dome during the startup process of the preburner of the SSME. (5) Study of the interaction between multiple sprays without and with swirl in their gaseous stream. The spray characteristics of single nozzles were compared with that of three identical nozzles with their axis at a small distance from each other. This study simulates the sprays in the preburner of the SSME, where there are around 260 elements on the faceplate of the combustion chamber. (6) Design an experimental facility to study the characteristics of sprays at high pressure conditions and at supercritical pressure and temperature for the gas but supercritical pressure and subcritical temperature for the liquid.

Process for Considering Special Exit Criteria from Bilingual/English as a Second Language (ESL) Services under 19 TAC §89.1225(k). School Year: 2013-2014, Grades 1-12

ERIC Educational Resources Information Center

Texas Education Agency, 2014

2014-01-01

Under Texas Administrative Code (TAC) §89.1225(h), districts are required to use the exit criteria represented in the chart titled "2013-2014 English Proficiency Exit Criteria Chart" found at (http://www.tea.state.tx.us/index2.aspx?id=4098) to exit English language learners (ELLs) from bilingual/ESL programs. The exit criteria under TAC…

The effect of riser end geometry on gas-solid hydrodynamics in a CFB riser operating in the core annular and dilute homogeneous flow regimes

DOE PAGES

Breault, Ronald W.; Monazam, Esmail R.; Shadle, Lawrence J.; ...

2017-02-12

Riser hydrodynamics are a function of the flow rates of gas and solids as well as the exit geometry, particularly when operated above the upper transport velocity. This work compares the exit voidage for multiple geometries and two different solids: Geldart group A glass beads and Geldart group B coke. Geometries were changed by modifying the volume of an abrupt T-shaped exit above the lateral riser exit. This was accomplished by positioning a plunger at various heights above the exit from zero to 0.38 m. A dimensionless expression used to predict smooth exit voidage was modified to account for themore » effect of the depth of the blind-T. The new correlation contains the solids-gas load ratio, solids-to-gas density ratio, bed-to-particle diameter ratio, gas Reynolds Number, as well as a term for the exit geometry. This study also found that there was a minimum riser roof height above the blind-T exit beyond which the riser exit voidage was not affected by the exit geometry. A correlation for this minimum riser roof height has also been developed in this study. This study covered riser superficial gas velocities of 4.35 to 7.7 m/s and solids circulation rates of 1.3 to 11.5 kg/s.« less

Disability Rises Gradually for a Cohort of Older Americans

PubMed Central

Brown, Dustin C.; Zajacova, Anna

2017-01-01

Objectives: We study changes in average disability over nearly two decades for a large epidemiological cohort of older Americans. As some people exit by mortality, do average disability levels for the living cohort rise rapidly, rise gradually, stay steady, or decline? Method: Data are from the Study of Asset and Health Dynamics Among the Oldest Old (AHEAD) cohort for 1993–2010. Cohort members are aged 70+ in 1993 (mean = 77.5 years), and the survivors are aged 87+ in 2010 (mean = 90.2 years). Personal care disability (activities of daily living), household management disability (instrumental activities of daily living), and physical limitations are studied. We study average disability for the living cohort over time and the disability histories for decedent and survivor groups. Results: Average disability rises gradually over time for the living cohort. Earlier decedent groups have higher average disability than later ones. Near death, disability rises sharply for all decedent groups. Longer surviving groups have less average disability, and slower disability increases, than shorter surviving groups. All results are repeated for younger cohort members (baseline age = 70–79 years), older ones (baseline age = 80+ years), women, and men. Discussion: As a cohort ages, average disability among living members increases gradually, signaling behavioral, psychological, and biological fitness in very old persons. PMID:26968638

Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

NASA Technical Reports Server (NTRS)

Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

1995-01-01

Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric balance measuring thrust and integrated pressure measurements along the length of the nozzle. Assessment of its value as a combustor performance evaluation tool will be conducted.

Design of a variable area diffuser for a 15-inch Mach 6 open-jet tunnel

NASA Technical Reports Server (NTRS)

Loney, Norman W.

1994-01-01

The Langley 15-inch Mach 6 High Temperature Tunnel was recently converted from a Mach 10 Hypersonic Flow Apparatus. This conversion was effected to improve the capability of testing in Mach 6 air at relatively high reservoir temperatures not previously possible at Langley. Elevated temperatures allow the matching of the Mach numbers, Reynolds numbers, and ratio of wall-to-adiabatic-wall temperatures (TW/Taw) between this and the Langley 20-inch Mach 6 CF4 Tunnel. This ratio is also matched for Langley's 31-inch Mach 10 Tunnel and is an important parameter useful in the simulation of slender bodies such as National Aerospace Plane (NASP) configurations currently being studied. Having established the nozzle's operating characteristics, the decision was made to install another test section to provide model injection capability. This test section is an open-jet type, with an injection system capable of injecting a model from retracted position to nozzle centerline between 0.5 and 2 seconds. Preliminary calibrations with the new test section resulted in Tunnel blockage. This blockage phenomenon was eliminated when the conical center body in the diffuser was replaced. The issue then, is to provide a new and more efficient variable area diffuser configuration with the capability to withstand testing of larger models without sending the Tunnel into an unstart condition. Use of the 1-dimensional steady flow equation with due regard to friction and heat transfer was employed to estimate the required area ratios (exit area / throat area) in a variable area diffuser. Correlations between diffuser exit Mach number and area ratios, relative to the stagnation pressure ratios and diffuser inlet Mach number were derived. From these correlations, one can set upper and lower operating pressures and temperatures for a given diffuser throat area. In addition, they will provide appropriate input conditions for the full 3-dimensional computational fluid dynamics (CFD) code for further simulation studies.

Factors Associated With Premature Exits From Supported Housing.

PubMed

Gabrielian, Sonya; Burns, Alaina V; Nanda, Nupur; Hellemann, Gerhard; Kane, Vincent; Young, Alexander S

2016-01-01

Many homeless consumers who enroll in supported housing programs--which offer subsidized housing and supportive services--disengage prematurely, before placement in permanent community-based housing. This study explored factors associated with exiting a supported housing program before achieving housing placement. With the use of administrative data, a roster was obtained for consumers enrolled in the Veterans Affairs (VA) Greater Los Angeles supported housing program from 2011 to 2012. Fewer (4%) consumers exited this program before achieving housing ("exiters") compared with consumers described in national VA figures (18%). Exiters with available demographic data (N=51) were matched 1:1 on age, gender, marital status, and race-ethnicity with consumers housed through this program ("stayers," N=51). Medical records were reviewed to compare diagnoses, health care utilization, housing histories, vocational history, and criminal justice involvement of exiters versus stayers. Exiters' housing outcomes were identified. Recursive partitioning identified variables that best differentiated exiters from stayers. Several factors were associated with premature exits from this supported housing program: residing in temporary housing on hospital grounds during program enrollment, poor adherence to outpatient care, substance use disorders, hepatitis C, chronic pain, justice involvement, frequent emergency department utilization, and medical-surgical admissions. The first of these factors and poor adherence to outpatient medical-surgical care best differentiated exiters from stayers. Moreover, >50% of exiters became street homeless or incarcerated after leaving the program. In that diverse social factors, diagnoses, and health care utilization patterns were associated with premature disengagement from supported housing, future research is needed to implement and evaluate rehabilitative services that address these factors, adapted to the context of supported housing.

Lower Granite Dam Smolt Monitoring Program, 2004-2005 Annual Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mensik, Fred; Rapp, Shawn; Ross Doug

2005-11-01

The 2004 fish collection season at Lower Granite Dam (LGR) was characterized by above average water temperatures, below average flows and spill, low levels of debris. The number of smolts collected for all species groups (with the exception of clipped and unclipped sockeye/kokanee) exceeded all previous collection numbers. With the continued release of unclipped supplementation chinook, steelhead and sockeye above LGR, we can not accurately distinguish wild chinook, wild steelhead and wild sockeye/kokanee from hatchery reared unclipped chinook and sockeye/kokanee in the sample. Wild steelhead can be identified from hatchery steelhead by the eroded dorsal and pectoral fins exhibited onmore » unclipped hatchery steelhead. The numbers in the wild columns beginning in 1998 include wild and unclipped hatchery origin smolts. This season a total of 11,787,539 juvenile salmonids was collected at LGR. Of these, 11,253,837 were transported to release sites below Bonneville Dam, 11,164,132 by barge and 89,705 by truck. An additional 501,395 fish were bypassed to the river due to over-capacity of the raceways and for research purposes. According to the PTAGIS database, 177,009 PIT-tagged fish were detected at LGR in 2004. Of these, 105,894 (59.8%) were bypassed through the PIT-tag diversion system, 69,130 (39.1%) were diverted to the raceways to be transported, 1,640 (0.9%) were diverted to the sample tank, sampled and then transported, 345 (0.2%) were undetected at any of the bypass, raceway or sample exit monitors.« less

Fractal heterogeneity in minimal matrix models of scars modulates stiff-niche stem-cell responses via nuclear exit of a mechanorepressor

NASA Astrophysics Data System (ADS)

Dingal, P. C. Dave P.; Bradshaw, Andrew M.; Cho, Sangkyun; Raab, Matthew; Buxboim, Amnon; Swift, Joe; Discher, Dennis E.

2015-09-01

Scarring is a long-lasting problem in higher animals, and reductionist approaches could aid in developing treatments. Here, we show that copolymerization of collagen I with polyacrylamide produces minimal matrix models of scars (MMMS), in which fractal-fibre bundles segregate heterogeneously to the hydrogel subsurface. Matrix stiffens locally--as in scars--while allowing separate control over adhesive-ligand density. The MMMS elicits scar-like phenotypes from mesenchymal stem cells (MSCs): cells spread and polarize quickly, increasing nucleoskeletal lamin-A yet expressing the `scar marker' smooth muscle actin (SMA) more slowly. Surprisingly, expression responses to MMMS exhibit less cell-to-cell noise than homogeneously stiff gels. Such differences from bulk-average responses arise because a strong SMA repressor, NKX2.5, slowly exits the nucleus on rigid matrices. NKX2.5 overexpression overrides rigid phenotypes, inhibiting SMA and cell spreading, whereas cytoplasm-localized NKX2.5 mutants degrade in well-spread cells. MSCs thus form a `mechanical memory' of rigidity by progressively suppressing NKX2.5, thereby elevating SMA in a scar-like state.

Consumption of particulate wastes derived from cage fish farming by aggregated wild fish. An experimental approach.

PubMed

Ballester-Moltó, M; Sanchez-Jerez, P; Aguado-Giménez, F

2017-09-01

Particulate wastes derived from cage fish farming are a trophic resource used by wild fish. This study assesses waste consumption by wild fish and the impact on the final balance of wastes. Consumption was determined according to the difference between the particulate matter exiting the cages and that reaching 5 m away at three different depths, in the presence and absence of wild fish. Wild fish around the experimental cages were counted during feeding and non-feeding periods. A weighted abundance of 1057 fish 1000 m -3 consumed 17.75% of the particulate wastes exiting the cages, on average. Consumption was higher below the cages, where waste outflow was greater. However, waste removal by wild fish was noteworthy along the shallow and deep sides of the cages. Wild fish diminished the net particulate wastes by about 14%, transforming them into more easily dispersible and less harmful wastes. This study demonstrates the mitigating potential of wild fish in reducing environmental impact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Breakup phenomena of a coaxial jet in the non-dilute region using real-time X-ray radiography

NASA Astrophysics Data System (ADS)

Cheung, F. B.; Kuo, K. K.; Woodward, R. D.; Garner, K. N.

1990-07-01

An innovative approach to the investigation of liquid jet breakup processes in the near-injector region has been developed to overcome the experimental difficulties associated with optically opaque, dense sprays. Real-time X-ray radiography (RTR) has been employed to observe the inner structure and breakup phenomena of coaxial jets. In the atomizing regime, droplets much smaller than the exit diameter are formed beginning essentially at the injector exit. Through the use of RTR, the instantaneous contour of the liquid core was visualized. Experimental results consist of controlled-exposure digital video images of the liquid jet breakup process. Time-averaged video images have also been recorded for comparison. A digital image processing system is used to analyze the recorded images by creating radiance level distributions of the jet. A rudimentary method for deducing intact-liquid-core length has been suggested. The technique of real-time X-ray radiography has been shown to be a viable approach to the study of the breakup processes of high-speed liquid jets.

34 CFR 682.604 - Required exit counseling for borrowers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 34 Education 4 2014-07-01 2014-07-01 false Required exit counseling for borrowers. 682.604 Section... counseling for borrowers. (a) Exit counseling. (1) A school must ensure that exit counseling is conducted... ensure that this counseling is conducted shortly before the student borrower ceases at least half-time...

14 CFR 27.1557 - Miscellaneous markings and placards.

Code of Federal Regulations, 2011 CFR

2011-01-01

...; (iii) For turbine engine powered rotorcraft, the permissible fuel designations; and (iv) For pressure...) Emergency exit placards. Each placard and operating control for each emergency exit must be red. A placard must be near each emergency exit control and must clearly indicate the location of that exit and its...

14 CFR 27.1557 - Miscellaneous markings and placards.

Code of Federal Regulations, 2013 CFR

2013-01-01

...; (iii) For turbine engine powered rotorcraft, the permissible fuel designations; and (iv) For pressure...) Emergency exit placards. Each placard and operating control for each emergency exit must be red. A placard must be near each emergency exit control and must clearly indicate the location of that exit and its...

14 CFR 27.1557 - Miscellaneous markings and placards.

Code of Federal Regulations, 2012 CFR

2012-01-01

...; (iii) For turbine engine powered rotorcraft, the permissible fuel designations; and (iv) For pressure...) Emergency exit placards. Each placard and operating control for each emergency exit must be red. A placard must be near each emergency exit control and must clearly indicate the location of that exit and its...

14 CFR 27.1557 - Miscellaneous markings and placards.

Code of Federal Regulations, 2014 CFR

2014-01-01

...; (iii) For turbine engine powered rotorcraft, the permissible fuel designations; and (iv) For pressure...) Emergency exit placards. Each placard and operating control for each emergency exit must be red. A placard must be near each emergency exit control and must clearly indicate the location of that exit and its...

36 CFR 13.1318 - Location of the EGDA.

Code of Federal Regulations, 2013 CFR

2013-07-01

... NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park Exit Glacier Developed... boundary to Exit Glacier Campground Entrance Road, all park areas within 350 meters (383 yards) of the centerline of the Exit Glacier Road; (2) From Exit Glacier Campground Entrance Road to the end of the main...

36 CFR 13.1318 - Location of the EGDA.

Code of Federal Regulations, 2011 CFR

2011-07-01

... NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park Exit Glacier Developed... boundary to Exit Glacier Campground Entrance Road, all park areas within 350 meters (383 yards) of the centerline of the Exit Glacier Road; (2) From Exit Glacier Campground Entrance Road to the end of the main...

36 CFR 13.1318 - Location of the EGDA.

Code of Federal Regulations, 2014 CFR

2014-07-01

... NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park Exit Glacier Developed... boundary to Exit Glacier Campground Entrance Road, all park areas within 350 meters (383 yards) of the centerline of the Exit Glacier Road; (2) From Exit Glacier Campground Entrance Road to the end of the main...

Computation of dark frames in digital imagers

NASA Astrophysics Data System (ADS)

Widenhorn, Ralf; Rest, Armin; Blouke, Morley M.; Berry, Richard L.; Bodegom, Erik

2007-02-01

Dark current is caused by electrons that are thermally exited into the conduction band. These electrons are collected by the well of the CCD and add a false signal to the chip. We will present an algorithm that automatically corrects for dark current. It uses a calibration protocol to characterize the image sensor for different temperatures. For a given exposure time, the dark current of every pixel is characteristic of a specific temperature. The dark current of every pixel can therefore be used as an indicator of the temperature. Hot pixels have the highest signal-to-noise ratio and are the best temperature sensors. We use the dark current of a several hundred hot pixels to sense the chip temperature and predict the dark current of all pixels on the chip. Dark current computation is not a new concept, but our approach is unique. Some advantages of our method include applicability for poorly temperature-controlled camera systems and the possibility of ex post facto dark current correction.

A novel high-temperature ejector-topping power cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freedman, B.Z.; Lior, N.

1994-01-01

A novel, patented topping power cycle is described that takes its energy from a very high-temperature heat source and in which the temperature of the heat sink is still high enough to operate another, conventional power cycle. The top temperatures heat source is used to evaporate a low saturation pressure liquid, which serves as the driving fluid for compressing the secondary fluid in an ejector. Due to the inherently simple construction of ejectors, they are well suited for operation at temperatures higher than those that can be used with gas turbines. The gases exiting from the ejector transfer heat tomore » the lower temperature cycle, and are separated by condensing the primary fluid. The secondary gas is then used to drive a turbine. For a system using sodium as the primary fluid and helium as the secondary fluid, and using a bottoming Rankine steam cycle, the overall thermal efficiency can be at least 11 percent better than that of conventional steam Rankine cycles.« less

Speed of sound measurements and mixing characterization of underexpanded fuel jets with supercritical reservoir condition using laser-induced thermal acoustics

NASA Astrophysics Data System (ADS)

Baab, S.; Förster, F. J.; Lamanna, G.; Weigand, B.

2016-11-01

The four-wave mixing technique laser-induced thermal acoustics was used to measure the local speed of sound in the farfield zone of extremely underexpanded jets. N-hexane at supercritical injection temperature and pressure (supercritical reservoir condition) was injected into quiescent subcritical nitrogen (with respect to the injectant). The technique's capability to quantify the nonisothermal, turbulent mixing zone of small-scale jets is demonstrated for the first time. Consistent radially resolved speed of sound profiles are presented for different axial positions and varying injection temperatures. Furthermore, an adiabatic mixing model based on nonideal thermodynamic properties is presented to extract mixture composition and temperature from the experimental speed of sound data. High fuel mass fractions of up to 94 % are found for the centerline at an axial distance of 55 diameters from the nozzle followed by a rapid decay in axial direction. This is attributed to a supercritical fuel state at the nozzle exit resulting in the injection of a high-density fluid. The obtained concentration data are complemented by existing measurements and collapsed in a similarity law. It allows for mixture prediction of underexpanded jets with supercritical reservoir condition provided that nonideal thermodynamic behavior is considered for the nozzle flow. Specifically, it is shown that the fuel concentration in the farfield zone is very sensitive to the thermodynamic state at the nozzle exit. Here, a transition from supercritical fluid to subcritical vapor state results in strongly varying fuel concentrations, which implies high impact on the mixture formation and, consequently, on the combustion characteristics.

Performance of a Model Rich Burn-quick Mix-lean Burn Combustor at Elevated Temperature and Pressure

NASA Technical Reports Server (NTRS)

Peterson, Christopher O.; Sowa, William A.; Samuelsen, G. S.

2002-01-01

As interest in pollutant emission from stationary and aero-engine gas turbines increases, combustor engineers must consider various configurations. One configuration of increasing interest is the staged, rich burn - quick mix - lean burn (RQL) combustor. This report summarizes an investigation conducted in a recently developed high pressure gas turbine combustor facility. The model RQL combustor was plenum fed and modular in design. The fuel used for this study is Jet-A which was injected from a simplex atomizer. Emission (CO2, CO, O2, UHC, NOx) measurements were obtained using a stationary exit plane water-cooled probe and a traversing water-cooled probe which sampled from the rich zone exit and the lean zone entrance. The RQL combustor was operated at inlet temperatures ranging from 367 to 700 K, pressures ranging from 200 to 1000 kPa, and combustor reference velocities ranging from 10 to 20 m/s. Variations were also made in the rich zone and lean zone equivalence ratios. Several significant trends were observed. NOx production increased with reaction temperature, lean zone equivalence ratio and residence time and decreased with increased rich zone equivalence ratio. NOx production in the model RQL combustor increased to the 0.4 power with increased pressure. This correlation, compared to those obtained for non-staged combustors (0.5 to 0.7), suggests a reduced dependence on NOx on pressure for staged combustors. Emissions profiles suggest that rich zone mixing is not uniform and that the rich zone contributes on the order of 16 percent to the total NOx produced.

Use of exit examinations: a criterion for graduation?

PubMed

Cullen, P D

1997-01-01

This study sought to measure the use of exit examinations in nursing schools at Historically Black Colleges and Universities (HBCU). Fifteen participants from HBCU nursing schools throughout the United States were surveyed to determine current practices related to exit exams. Overall, fourteen schools (93.33%) used an exit exam at the end of their nursing program. However, 73.33% of the participants (11 schools) reported it was mandatory for students to pass the exam as a requirement for graduation. Almost 47% of the participants (7 schools) reported the use of the exit exam was related to NCLEX-RN pass rates, while others reported identification of student needs as the primary reason for using an exit exam. Most participants were very helpful by sharing their innovations. While this small study provided some information on the use of exit examinations, more research is needed to substantiate both the appropriateness and usefulness of their use in baccalaureate degree nursing programs.

Spatial signals link exit from mitosis to spindle position.

PubMed

Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

2016-05-11

In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT- bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

Crowd evacuation model based on bacterial foraging algorithm

NASA Astrophysics Data System (ADS)

Shibiao, Mu; Zhijun, Chen

To understand crowd evacuation, a model based on a bacterial foraging algorithm (BFA) is proposed in this paper. Considering dynamic and static factors, the probability of pedestrian movement is established using cellular automata. In addition, given walking and queue times, a target optimization function is built. At the same time, a BFA is used to optimize the objective function. Finally, through real and simulation experiments, the relationship between the parameters of evacuation time, exit width, pedestrian density, and average evacuation speed is analyzed. The results show that the model can effectively describe a real evacuation.

46 CFR 185.606 - Escape hatches and emergency exits.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Escape hatches and emergency exits. 185.606 Section 185... 100 GROSS TONS) OPERATIONS Markings Required § 185.606 Escape hatches and emergency exits. All escape hatches and other emergency exits used as means of escape must be marked on both sides in clearly legible...

46 CFR 169.745 - Escape hatches and emergency exits.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Escape hatches and emergency exits. 169.745 Section 169... VESSELS Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.745 Escape hatches and emergency exits. Each escape hatch and other emergency exit must be marked on both sides using at least 1...

46 CFR 185.606 - Escape hatches and emergency exits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Escape hatches and emergency exits. 185.606 Section 185... 100 GROSS TONS) OPERATIONS Markings Required § 185.606 Escape hatches and emergency exits. All escape hatches and other emergency exits used as means of escape must be marked on both sides in clearly legible...

46 CFR 169.745 - Escape hatches and emergency exits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Escape hatches and emergency exits. 169.745 Section 169... VESSELS Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.745 Escape hatches and emergency exits. Each escape hatch and other emergency exit must be marked on both sides using at least 1...

46 CFR 185.606 - Escape hatches and emergency exits.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Escape hatches and emergency exits. 185.606 Section 185... 100 GROSS TONS) OPERATIONS Markings Required § 185.606 Escape hatches and emergency exits. All escape hatches and other emergency exits used as means of escape must be marked on both sides in clearly legible...

46 CFR 185.606 - Escape hatches and emergency exits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Escape hatches and emergency exits. 185.606 Section 185... 100 GROSS TONS) OPERATIONS Markings Required § 185.606 Escape hatches and emergency exits. All escape hatches and other emergency exits used as means of escape must be marked on both sides in clearly legible...

46 CFR 169.745 - Escape hatches and emergency exits.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Escape hatches and emergency exits. 169.745 Section 169... VESSELS Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.745 Escape hatches and emergency exits. Each escape hatch and other emergency exit must be marked on both sides using at least 1...

46 CFR 169.745 - Escape hatches and emergency exits.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Escape hatches and emergency exits. 169.745 Section 169... VESSELS Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.745 Escape hatches and emergency exits. Each escape hatch and other emergency exit must be marked on both sides using at least 1...

46 CFR 169.745 - Escape hatches and emergency exits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Escape hatches and emergency exits. 169.745 Section 169... VESSELS Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.745 Escape hatches and emergency exits. Each escape hatch and other emergency exit must be marked on both sides using at least 1...

46 CFR 185.606 - Escape hatches and emergency exits.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Escape hatches and emergency exits. 185.606 Section 185... 100 GROSS TONS) OPERATIONS Markings Required § 185.606 Escape hatches and emergency exits. All escape hatches and other emergency exits used as means of escape must be marked on both sides in clearly legible...

An Entrance to Exit Polling: Strategies for Using Exit Polls as Experiential Learning Projects

ERIC Educational Resources Information Center

Berry, Michael J.; Robinson, Tony

2012-01-01

Engaging students in the design, administration, and postelection analysis of an exit poll can be an excellent experiential learning activity. Lelieveldt and Rossen (2009) argue that exit polls are a "perfect teaching tool" because they provide students with a cooperative (rather than competitive) learning experience; help students…

40 CFR 63.3176 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... automobiles or light-duty trucks, including coating facilities and processes. Bake oven air seal means an entry or entry vestibule to or an exit or exit vestibule from a bake oven which isolates the bake oven... exit or exit vestibule) the bake oven. No significant VOC generating activity takes place in a bake...

Exit Cards: Creating a Dialogue for Continuous Evaluation

ERIC Educational Resources Information Center

Patka, Mazna; Wallin-Ruschman, Jennifer; Wallace, Tenille; Robbins, Candice

2016-01-01

This study explored the use of Exit Cards, which are formative evaluations of student knowledge and instruction undertaken at every class meeting. Its results are based on Exit Card data from two undergraduate research methods courses. Thematic analysis indicated that students used Exit Cards to communicate (1) what they learned, (2) challenges…

8 CFR 215.9 - Temporary Worker Visa Exit Program.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Temporary Worker Visa Exit Program. 215.9... ALIENS DEPARTING FROM THE UNITED STATES § 215.9 Temporary Worker Visa Exit Program. An alien admitted on certain temporary worker visas at a port of entry participating in the Temporary Worker Visa Exit Program...

8 CFR 215.9 - Temporary Worker Visa Exit Program.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Temporary Worker Visa Exit Program. 215.9... ALIENS DEPARTING FROM THE UNITED STATES § 215.9 Temporary Worker Visa Exit Program. An alien admitted on certain temporary worker visas at a port of entry participating in the Temporary Worker Visa Exit Program...

8 CFR 215.9 - Temporary Worker Visa Exit Program.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Temporary Worker Visa Exit Program. 215.9... ALIENS DEPARTING FROM THE UNITED STATES § 215.9 Temporary Worker Visa Exit Program. An alien admitted on certain temporary worker visas at a port of entry participating in the Temporary Worker Visa Exit Program...

8 CFR 215.9 - Temporary Worker Visa Exit Program.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Temporary Worker Visa Exit Program. 215.9... ALIENS DEPARTING FROM THE UNITED STATES § 215.9 Temporary Worker Visa Exit Program. An alien admitted on certain temporary worker visas at a port of entry participating in the Temporary Worker Visa Exit Program...

8 CFR 215.9 - Temporary Worker Visa Exit Program.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Temporary Worker Visa Exit Program. 215.9... ALIENS DEPARTING FROM THE UNITED STATES § 215.9 Temporary Worker Visa Exit Program. An alien admitted on certain temporary worker visas at a port of entry participating in the Temporary Worker Visa Exit Program...

Exit Exam as Academic Performance Indicator

ERIC Educational Resources Information Center

Al Ahmad, Mahmoud; Al Marzouqi, Ali H.; Hussien, Mousa

2014-01-01

This paper focuses on the impact of exit exams on different elements of the educational process, namely: curriculum development, students and instructors. A 50-question multiple-choice Exit Exam was prepared by Electrical Engineering (EE) faculty members covering a poll of questions from EE core courses. A copy of the Exit Exam applied during each…

Measurement of atmospheric pressure microplasma jet with Langmuir probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Kunning G., E-mail: gabe.xu@uah.edu; Doyle, Steven J.

2016-09-15

A radio frequency argon microplasma jet at atmospheric-pressure is characterized using Langmuir probes. While optical methods are the typical diagnostic for these small scale plasmas, the simplicity and low cost of Langmuir probes makes them an attractive option. The plasma density and electron temperature are measured using existing high-pressure Langmuir probe theories developed for flames and arcs. The density and temperature vary from 1 × 10{sup 16} to 1 × 10{sup 19} m{sup −3} and 2.3 to 4.4 eV, respectively, depending on the operating condition. The density decreases while the electron temperature increases with axial distance from the jet exit. Themore » applicability of the probe theories as well as the effect of collisionality and jet mixing is discussed.« less

Performance of a high-work low aspect ratio turbine tested with a realistic inlet radial temperature profile

NASA Technical Reports Server (NTRS)

Stabe, R. G.; Whitney, W. J.; Moffitt, T. P.

1984-01-01

Experimental results are presented for a 0.767 scale model of the first stage of a two-stage turbine designed for a high by-pass ratio engine. The turbine was tested with both uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The inlet temperature profile was essentially mixed-out in the rotor. There was also substantial underturning of the exit flow at the mean diameter. Both of these effects were attributed to strong secondary flows in the rotor blading. There were no significant differences in the stage performance with either inlet condition when differences in tip clearance were considered. Performance was very close to design intent in both cases. Previously announced in STAR as N84-24589

Apparatus and method for controlling the secondary injection of fuel

DOEpatents

Martin, Scott M.; Cai, Weidong; Harris, Jr., Arthur J.

2013-03-05

A combustor (28) for a gas turbine engine is provided comprising a primary combustion chamber (30) for combusting a first fuel to form a combustion flow stream (50) and a transition piece (32) located downstream from the primary combustion chamber (30). The transition piece (32) comprises a plurality of injectors (66) located around a circumference of the transition piece (32) for injecting a second fuel into the combustion flow stream (50). The injectors (66) are effective to create a radial temperature profile (74) at an exit (58) of the transition piece (32) having a reduced coefficient of variation relative to a radial temperature profile (64) at an inlet (54) of the transition piece (32). Methods for controlling the temperature profile of a secondary injection are also provided.

Performance of high-area-ratio annular dump diffuser using suction-stabilized-vortex flow control

NASA Technical Reports Server (NTRS)

Juhasz, A. J.; Smith, J. M.

1977-01-01

A short annular dump diffuser having a geometry conductive to formation of suction stabilized toroidal vortices in the region of abrupt area change was tested. The overall diffuser area ratio was 4.0 and the length to inlet height ratio was 2.0. Performance data were obtained at near ambient temperature and pressure for inlet Mach numbers of 0.18 and 0.30 with suction rates ranging from 0 to 18 percent of total inlet mass flowrate. Results show that the exit velocity profile could be readily biased toward either wall by adjustment of inner and outer wall suction rates. Symmetric exit velocity profiles were inherently unstable with a tendency to revert to a hub or tip bias. Diffuser effectiveness was increased from about 38 percent without suction to over 85 percent at a total suction rate of 10 to 12 percent. At the same time diffuser total pressure loss was reduced from 3.1 percent to 1.1 percent at an inlet Mach number of 0.3.

Unsteady heat transfer in turbine blade ducts: Focus on combustor sources

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Huff, Ronald

1988-01-01

Thermal waves generated by either turbine rotor blades cutting through nonuniform combustor temperature fields or unsteady burning could lead to thermal fatigue cracking in the blades. To determine the magnitude of the thermal oscillation in blades with complex shapes and material compositions, a finite element Galerkin formulation has been developed to study combustor generated thermal wave propagation in a model two-dimensional duct with a uniform plug flow profile. The reflection and transmission of the thermal waves at the entrance and exit boundaries are determined by coupling the finite element solutions at the entrance and exit to the eigenfunctions of an infinitely long adiabatic duct. Example solutions are presented. In general, thermal wave propagation from an air passage into a metallic blade wall is small and not a problem. However, if a thermal barrier coating is applied to a metallic surface under conditions of a high heat transfer, a good impedance match is obtained and a significant portion of the thermal wave can pass into the blade material.

Shapes of Nonbuoyant Round Luminous Laminar-Jet Diffusion Flames in Coflowing Air. Appendix F

NASA Technical Reports Server (NTRS)

Lin, K.-C.; Faeth, G. M.; Urban, David L. (Technical Monitor)

2000-01-01

The shapes (luminous flame boundaries) of steady nonbuoyant round luminous hydrocarbon-fueled laminar-jet diffusion flames in coflowing air were studied both experimentally and theoretically. Flame shapes were measured from photographs of flames burning at low pressures in order to minimize the effects of buoyancy. Test conditions involved acetylene-, propylene. and 1,3-butadiene-fueled flames having initial reactant temperatures of 300 K, ambient pressures of 19-50 kPa, jet-exit Reynolds numbers of 18-121, and initial air/fuel velocity ratios of 0.22-32.45 to yield luminous flame lengths of 21-198 mm. The present flames were close to the laminar smoke point but were not soot emitting. Simple expressions to estimate the shapes of nonbuoyant laminar-jet diffusion flames in coflow were found by extending an earlier analysis of Mahalingam et al. These formulas provided a good correlation of present measurements except near the burner exit where self-similar approximations used in the simplified analysis are no longer appropriate.

An experimental study of turbine vane heat transfer with leading edge and downstream film cooling

NASA Astrophysics Data System (ADS)

Nirmalan, V.; Hylton, L. D.

1989-06-01

This paper presents the effects of downstream film cooling, with and without leading edge showerhead film cooling, on turbine-vane external heat transfer. Steady-state experimental measurements were made in a three-vane linear two-dimensional cascade. The principal independent parameters were maintained over ranges consistent with actual engine conditions. The test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. The data obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The downstream film cooling process was shown to be a complex interaction of two competing mechanisms. The thermal dilution effect, associated with the injection of relatively cold fluid, results in a decrease in the heat transfer to the airfoil. Conversely, the turbulence augmentation, produced by the injection process, results in increased heat transfer to the airfoil.

A Matlab-Based Graphical User Interface for Simulation and Control Design of a Hydrogen Mixer

NASA Technical Reports Server (NTRS)

Richter, Hanz; Figueroa, Fernando

2003-01-01

A Graphical User Interface (GUI) that facilitates prediction and control design tasks for a propellant mixer is described. The Hydrogen mixer is used in rocket test stand operations at the NASA John C. Stennis Space Center. The mixer injects gaseous hydrogen (GH2) into a stream of liquid hydrogen (LH2) to obtain a combined flow with desired thermodynamic properties. The flows of GH2 and LH2 into the mixer are regulated by two control valves, and a third control valve is installed at the exit of the mixer to regulate the combined flow. The three valves may be simultaneously operated in order to achieve any desired combination of total flow, exit temperature and mixer pressure within the range of operation. The mixer, thus, constitutes a three-input, three-output system. A mathematical model of the mixer has been obtained and validated with experimental data. The GUI presented here uses the model to predict mixer response under diverse conditions.

An experimental study of turbine vane heat transfer with leading edge and downstream film cooling

NASA Technical Reports Server (NTRS)

Nirmalan, V.; Hylton, L. D.

1989-01-01

This paper presents the effects of downstream film cooling, with and without leading edge showerhead film cooling, on turbine-vane external heat transfer. Steady-state experimental measurements were made in a three-vane linear two-dimensional cascade. The principal independent parameters were maintained over ranges consistent with actual engine conditions. The test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. The data obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The downstream film cooling process was shown to be a complex interaction of two competing mechanisms. The thermal dilution effect, associated with the injection of relatively cold fluid, results in a decrease in the heat transfer to the airfoil. Conversely, the turbulence augmentation, produced by the injection process, results in increased heat transfer to the airfoil.

A double-blind block randomized clinical trial on the effect of zinc as a treatment for diarrhea in neonatal Holstein calves under natural challenge conditions.

PubMed

Glover, A D; Puschner, B; Rossow, H A; Lehenbauer, T W; Champagne, J D; Blanchard, P C; Aly, S S

2013-11-01

Diarrhea is the leading cause of death in neonatal calves and contributes to major economic losses. The objective of this double-blind randomized clinical trial was to evaluate the effect of oral inorganic or organic zinc supplementation as a treatment for neonatal diarrhea in calves. Seventy nine 1 to 8 day old male Holstein calves on a California calf ranch were block randomized to one of 3 treatments within 24h from their first onset of diarrhea. Calves received a daily dose of either a placebo composed of 80 mg of zinc-free powder, 381.54 mg of zinc methionine (Met) (equivalent to 80 mg of zinc), or 99.69 mg of zinc oxide (ZO) (equivalent to 80 mg of zinc) in 2L of a zinc-free oral rehydration solution (ORS). Calves were treated once daily until normal fecal consistency or for a maximum of 14 days. Upon enrollment and exit, calves were weighed, and blood, feces, and liver biopsies were collected for trace mineral analysis. Fecal samples at enrollment and exit were tested for E. coli K99, Cryptosporidium spp., rotavirus and coronavirus. Pre-treatment liver zinc concentrations for the 71 calves in the placebo, zinc Met, and ZO treatment groups were 710.6 (SEM=147.7), 852.3 (SEM=129.6), and 750.7 (SEM=202.9)mg/kg dry weight (DW), respectively. Exit liver zinc concentrations for the calves in the placebo, zinc Met, and ZO treatment groups were 728.9 (SEM=182.9), 1141.0 (SEM=423.8), and 636.8 (SEM=81.5)mg/kg dry weight, respectively. Although statistically non-significant, there were clinically important findings identified for each of zinc Met and ZO treatments. Calves treated with zinc Met gained on average 40 g/day during a diarrhea episode compared to a weight loss of 67 g/day on average in the placebo-treated calves (Power 19.9%). Calves treated with ZO had 1.4 times higher hazard of clinical cure compared to calves in the placebo group (Power 5.3%). Calves that were fecal positive to cryptosporidium spp. at enrollment and treated with zinc Met had higher odds of testing negative at exit compared to placebo calves (Odds Ratio (OR)=16.0). In contrast, calves treated with ZO tended to recover (fecal score=1) one day earlier compared to calves treated with a placebo (8.5 d vs. 9.7 d). The current trial identified clinically important findings that warrant further research to investigate zinc's therapeutic effect for calf diarrhea. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Effects of temperament and acclimation to handling on feedlot performance of Bos taurus feeder cattle originated from a rangeland-based cow-calf system.

PubMed

Francisco, C L; Cooke, R F; Marques, R S; Mills, R R; Bohnert, D W

2012-12-01

Two experiments evaluated the effects of temperament and acclimation to handling on performance of Angus × Hereford feeder cattle reared in extensive rangeland systems until weaning. In Exp. 1, 200 calves (n = 97 for yr 1; n = 103 for yr 2) were evaluated for temperament at weaning (average age ± SE = 152 ± 1 d) by chute score and exit velocity. Chute score was assessed on a 5-point scale according to behavior during chute restraining. Exit score was calculated by dividing exit velocity into quintiles and assigning calves a score from 1 (slowest) to 5 (fastest). A temperament score was calculated for each calf by averaging chute and exit scores. Calf temperament was classified according to temperament score as adequate (≤3) or excitable (>3). After weaning, calves were assigned to a 40-d preconditioning followed by growing (139 d) and finishing (117 d) phases until slaughter. Weaning BW was decreased (P = 0.04) in excitable calves compared with adequate calves. No differences were detected (P ≥ 0.21) for ADG during preconditioning, growing, and finishing phases; hence, excitable calves tended (P = 0.09) to have decreased HCW compared with adequate calves. In Exp. 2, 60 steers (initial age ± SE = 198 ± 2 d) were weighed and evaluated for temperament score 35 d after weaning (d -29). On d -28, steers were ranked by these variables and assigned to receive an acclimation treatment or not (control). Acclimated steers were processed through a handling facility twice weekly for 4 wk (d -28 to -1) whereas control steers remained undisturbed on pasture. On d 0, all steers were transported for 24 h and returned to the research facility (d 1). On arrival, steers were ranked by BW within treatment and randomly assigned to 20 feedlot pens for a 28-d feedlot receiving period. Acclimated steers had decreased temperament score and plasma cortisol compared with controls on d 0 (P = 0.02). During feedlot receiving, acclimated steers had decreased ADG (P < 0.01) and G:F (P = 0.03) and tended to have decreased DMI (P = 0.07) compared with controls. Acclimated steers had greater plasma haptoglobin on d 4 (P = 0.04) and greater ceruloplasmin from d 0 to 10 (P ≤ 0.04) and tended to have greater cortisol on d 1 (P = 0.08) than controls. In conclusion, temperament affects productivity of beef operations based on Bos taurus feeder cattle reared in extensive rangeland systems until weaning whereas acclimation to handling ameliorated cattle temperament but did not benefit feedlot receiving performance.

Tables of critical-flow functions and thermodynamic properties for methane and computational procedures for both methane and natural gas

NASA Technical Reports Server (NTRS)

Johnson, R. C.

1972-01-01

Procedures for calculating the mass flow rate of methane and natural gas through nozzles are given, along with the FORTRAN 4 subroutines used to make these calculations. Three sets of independent variables are permitted in these routines. In addition to the plenum pressure and temperature, the third independent variable is either nozzle exit pressure, Mach number, or temperature. A critical-flow factor that becomes a convenient means for determining the mass flow rate of methane through critical-flow nozzles is tabulated. Other tables are included for nozzle throat velocity and critical pressure, density, and temperature ratios, along with some thermodynamic properties of methane, including compressibility factor, enthalpy, entropy, specific heat, specific-heat ratio, and speed of sound. These tabulations cover a temperature range from 120 to 600 K and pressures to 3 million N/sq m.

Experimental Investigation of Reacting Flow Characteristics in a Dual-Mode Scramjet Combustor

NASA Astrophysics Data System (ADS)

Shi, Deyong; Song, Wenyan; Ye, Jingfeng; Tao, Bo; Wang, Yanhua

2016-06-01

In this work, a hydrogen-fueled dual-mode scramjet combustor was investigated experimentally. Clean and dry air was supplied to the combustor through a Mach 2 nozzle with a total temperature of 800 K and a total pressure of 800 kPa. The high enthalpy air was provided by an electricity resistance heater. Room temperature hydrogen was injected with sonic speed from injector orifices vertically, and downstream the injector a tandem cavity flame holder was mounted. Except wall pressure profiles, velocity and temperature profiles in and at exit of the combustor were also measured using hydroxyl tagging velocimetry (HTV) and tunable diode laser absorption spectroscopy (TDLAS), respectively. Results showed that combustion occurred mainly at the bottom side of the combustor. And there were also an extreme disparity of the velocity and temperature profiles along the Y-direction, i.e. the transverse direction.

Dynamics of DNA breathing: weak noise analysis, finite time singularity, and mapping onto the quantum Coulomb problem.

PubMed

Fogedby, Hans C; Metzler, Ralf

2007-12-01

We study the dynamics of denaturation bubbles in double-stranded DNA on the basis of the Poland-Scheraga model. We show that long time distributions for the survival of DNA bubbles and the size autocorrelation function can be derived from an asymptotic weak noise approach. In particular, below the melting temperature the bubble closure corresponds to a noisy finite time singularity. We demonstrate that the associated Fokker-Planck equation is equivalent to a quantum Coulomb problem. Below the melting temperature, the bubble lifetime is associated with the continuum of scattering states of the repulsive Coulomb potential; at the melting temperature, the Coulomb potential vanishes and the underlying first exit dynamics exhibits a long time power law tail; above the melting temperature, corresponding to an attractive Coulomb potential, the long time dynamics is controlled by the lowest bound state. Correlations and finite size effects are discussed.

Test results of low NO(x) catalytic combustors for gas turbines

NASA Astrophysics Data System (ADS)

Ozawa, Y.; Hirano, J.; Sato, M.; Saiga, M.; Watanabe, S.

1994-07-01

Catalytic combustion is an ultralow NO(x) combustion method, so it is expected that this method will be applied to a gas turbine combustor. However, it is difficult to develop a catalytic combustor because catalytic reliability at high temperature is still insufficient. To overcome this difficulty, we designed a catalytic combust gas at a combustion temperature of 1300 C while keeping the catalytic temperature below 1000 C. After performing preliminary tests using LPG, we designed two types of combustor for natural gas with a capacity equivalent to one combustor used in a 20 MW class multican-type gas turbine. Combustion tests were conducted at atmospheric pressure using natural gas. As a result, it was confirmed that a combustor in which catalytic combustor segments were arranged alternately with premixing nozzles could achieve low NO(x) and high combustion efficiency in the range from 1000 C to 1300 C of the combustor exit gas temperature.

Langmuir Probe Measurements Within the Discharge Channel of the 20-kW NASA-300M and NASA-300MS Hall Thrusters

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Huang, Wensheng; Haag, Thomas W.; Kamhawi, Hani

2013-01-01

NASA is presently developing a high-power, high-efficiency, long-lifetime Hall thruster for the Solar Electric Propulsion Technology Demonstration Mission. In support of this task, studies have been performed on the 20-kW NASA-300M Hall thruster to aid in the overall design process. The ability to incorporate magnetic shielding into a high-power Hall thruster was also investigated with the NASA- 300MS, a modified version of the NASA-300M. The inclusion of magnetic shielding would allow the thruster to push existing state-of-the-art technology in regards to service lifetime, one of the goals of the Technology Demonstration Mission. Langmuir probe measurements were taken within the discharge channels of both thrusters in order to characterize differences at higher power levels, as well as validate ongoing modeling efforts using the axisymmetric code Hall2De. Flush-mounted Langmuir probes were also used within the channel of the NASA-300MS to verify that magnetic shielding was successfully applied. Measurements taken from 300 V, 10 kW to 600 V, 20 kW have shown plasma potentials near anode potential and electron temperatures of 4 to 12 eV at the walls near the thruster exit plane of the NASA-300MS, verifying magnetic shielding and validating the design process at this power level. Channel centerline measurements on the NASA-300M from 300 V, 10 kW to 500 V, 20 kW show the electron temperature peak at approximately 0.1 to 0.2 channel lengths upstream of the exit plane, with magnitudes increasing with discharge voltage. The acceleration profiles appear to be centered about the exit plane with a width of approximately 0.3 to 0.4 channel lengths. Channel centerline measurements on the NASA-300MS were found to be more challenging due to additional probe heating. Ionization and acceleration zones appeared to move downstream on the NASA-300MS compared to the NASA-300M, as expected based on the shift in peak radial magnetic field. Additional measurements or alternative diagnostics will be needed to verify peak electron temperatures in the NASA-300MS and compare them with model predictions.

Differences in Student Achievement between Early-Exit and Late-Exit Bilingual Programs: A Multiyear, Statewide Investigation

ERIC Educational Resources Information Center

Martinez, Rosa Maria

2014-01-01

Purpose The purpose of this study was to examine the difference between two bilingual program types: traditional early-exit and late-exit bilingual programs and academic achievement using archival data from the Texas Education Agency Public Education Information Management System. An examination of academic achievement rates across a 3-year period…

Relationship between cattle temperament as determined by exit velocity carcass merit in beef cattle

USDA-ARS?s Scientific Manuscript database

The objective of this trial was to use cattle temperament, as determined by exit velocity only, as a means to evaluate the impact of temperament on carcass merit and the possible utilization of exit velocity alone as a sorting tool within the feedlot. At the time of processing, exit velocity and bod...

Exit Strategies: How Low-Performing High Schools Respond to High School Exit Examination Requirements

ERIC Educational Resources Information Center

Holme, Jennifer Jellison

2013-01-01

Background: Over the past several decades, a significant number of states have either adopted or increased high school exit examination requirements. Although these policies are intended to generate improvement in schools, little is known about how high schools are responding to exit testing pressures. Purpose: This study examined how five…

24 CFR 3280.106 - Exit facilities; egress windows and devices.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Exit facilities; egress windows and... § 3280.106 Exit facilities; egress windows and devices. (a) Every room designed expressly for sleeping purposes, unless it has an exit door (see § 3280.105), shall have at least one outside window or approved...

Exit Exams: Decreases or Increases the Dropout Rate

ERIC Educational Resources Information Center

Barnes, Teresa A.

2009-01-01

The purpose of this paper was to examine the impact of exit exams on the dropout rate. Data was gathered from several research articles. The most impressionable research revealed exit exams have a negative effect on minorities, especially black males. Results indicate by 2012, that exit exams in 25 states will affect 81 percent of minority high…

Rotor with Flattened Exit Pressure Profile

NASA Technical Reports Server (NTRS)

Baltas, Constantine (Inventor); Prasad, Dilip (Inventor); Gallagher, Edward J. (Inventor)

2015-01-01

A rotor blade comprises an airfoil extending radially from a root section to a tip section and axially from a leading edge to a trailing edge, the leading and trailing edges defining a curvature therebetween. The curvature determines a relative exit angle at a relative span height between the root section and the tip section, based on an incident flow velocity at the leading edge of the airfoil and a rotational velocity at the relative span height. In operation of the rotor blade, the relative exit angle determines a substantially flat exit pressure ratio profile for relative span heights from 75% to 95%, wherein the exit pressure ratio profile is constant within a tolerance of 10% of a maximum value of the exit pressure ratio profile.

Evaluation of the Performance and Flow in an Axial Compressor.

DTIC Science & Technology

1982-10-01

A Exit Rake P 11.00-P tP noz P2noz -PA SP-1 PHub - PA Exit Rake Pt11.50-Pt p - PA SP-1 PTip - PA Exit Rake Pt2.00-PPtpipe ATp Att Pspipe - PA SP-2...PTip - PA Exit Rake Pt6.50-Pt Inlet Rake Pt14.40-PA SP-8 PTip - PA Exit Rake Pt 17.00-Pt Inlet Rake Pt 1.30-PA SP-8 PHub - PA Exit Rake Pt17.50-Pt...Determination from Probe Pressures Pt (1) =((Pt=(1) + Phub ) + (Pt(1) + Pt(2)))/3 P t(2) P t(2) Pt (3) = t(3) P t(4) = (P t(3) + P t(4))/2 P t(5) =P t(4) Pt

Three-dimensional inviscid analysis of radial-turbine flow and a limited comparison with experimental data

NASA Technical Reports Server (NTRS)

Choo, Y. K.; Civinskas, K. C.

1985-01-01

The three-dimensional inviscid DENTON code is used to analyze flow through a radial-inflow turbine rotor. Experimental data from the rotor are compared with analytical results obtained by using the code. The experimental data available for comparison are the radial distributions of circumferentially averaged values of absolute flow angle and total pressure downstream of the rotor exit. The computed rotor-exit flow angles are generally underturned relative to the experimental values, which reflect the boundary-layer separation at the trailing edge and the development of wakes downstream of the rotor. The experimental rotor is designed for a higher-than-optimum work factor of 1.126 resulting in a nonoptimum positive incidence and causing a region of rapid flow adjustment and large velocity gradients. For this experimental rotor, the computed radial distribution of rotor-exit to turbine-inlet total pressure ratios are underpredicted due to the errors in the finite-difference approximations in the regions of rapid flow adjustment, and due to using the relatively coarser grids in the middle of the blade region where the flow passage is highly three-dimensional. Additional results obtained from the three-dimensional inviscid computation are also presented, but without comparison due to the lack of experimental data. These include quasi-secondary velocity vectors on cross-channel surfaces, velocity components on the meridional and blade-to-blade surfaces, and blade surface loading diagrams. Computed results show the evolution of a passage vortex and large streamline deviations from the computational streamwise grid lines. Experience gained from applying the code to a radial turbine geometry is also discussed.

Imitate or innovate? Children's innovation is influenced by the efficacy of observed behaviour.

PubMed

Carr, Kayleigh; Kendal, Rachel L; Flynn, Emma G

2015-09-01

This study investigated the age at which children judge it futile to imitate unreliable information, in the form of a visibly ineffective demonstrated solution, and deviate to produce novel solutions ('innovations'). Children aged 4-9 years were presented with a novel puzzle box, the Multiple-Methods Box (MMB), which offered multiple innovation opportunities to extract a reward using different tools, access points and exits. 209 children were assigned to conditions in which eight social demonstrations of a reward retrieval method were provided; each condition differed incrementally in terms of the method's efficacy (0%, 25%, 75%, and 100% success at extracting the reward). An additional 47 children were assigned to a no-demonstration control condition. Innovative reward extractions from the MMB increased with decreasing efficacy of the demonstrated method. However, imitation remained a widely used strategy irrespective of the efficacy of the method being reproduced (90% of children produced at least one imitative attempt, and imitated on an average of 4.9 out of 8 attempt trials). Children were more likely to innovate in relation to the tool than exit, even though the latter would have been more effective. Overall, innovation was rare: only 12.4% of children innovated by discovering at least one novel reward exit. Children's prioritisation of social information is consistent with theories of cultural evolution indicating imitation is a prepotent response following observation of behaviour, and that innovation is a rarity; so much so, that even maladaptive behaviour is copied. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Three-dimensional inviscid analysis of radial turbine flow and a limited comparison with experimental data

NASA Technical Reports Server (NTRS)

Choo, Y. K.; Civinskas, K. C.

1985-01-01

The three-dimensional inviscid DENTON code is used to analyze flow through a radial-inflow turbine rotor. Experimental data from the rotor are compared with analytical results obtained by using the code. The experimental data available for comparison are the radial distributions of circumferentially averaged values of absolute flow angle and total pressure downstream of the rotor exit. The computed rotor-exit flow angles are generally underturned relative to the experimental values, which reflect the boundary-layer separation at the trailing edge and the development of wakes downstream of the rotor. The experimental rotor is designed for a higher-than-optimum work factor of 1.126 resulting in a nonoptimum positive incidence and causing a region of rapid flow adjustment and large velocity gradients. For this experimental rotor, the computed radial distribution of rotor-exit to turbine-inlet total pressure ratios are underpredicted due to the errors in the finite-difference approximations in the regions of rapid flow adjustment, and due to using the relatively coarser grids in the middle of the blade region where the flow passage is highly three-dimensional. Additional results obtained from the three-dimensional inviscid computation are also presented, but without comparison due to the lack of experimental data. These include quasi-secondary velocity vectors on cross-channel surfaces, velocity components on the meridional and blade-to-blade surfaces, and blade surface loading diagrams. Computed results show the evolution of a passage vortex and large streamline deviations from the computational streamwise grid lines. Experience gained from applying the code to a radial turbine geometry is also discussed.

Examination of the Armagh Observatory Annual Mean Temperature Record, 1844-2004

NASA Technical Reports Server (NTRS)

Wilson, Robert M.; Hathaway, David H.

2006-01-01

The long-term annual mean temperature record (1844-2004) of the Armagh Observatory (Armagh, Northern Ireland, United Kingdom) is examined for evidence of systematic variation, in particular, as related to solar/geomagnetic forcing and secular variation. Indeed, both are apparent in the temperature record. Moving averages for 10 years of temperature are found to highly correlate against both 10-year moving averages of the aa-geomagnetic index and sunspot number, having correlation coefficients of approx. 0.7, inferring that nearly half the variance in the 10-year moving average of temperature can be explained by solar/geomagnetic forcing. The residuals appear episodic in nature, with cooling seen in the 1880s and again near 1980. Seven of the last 10 years of the temperature record has exceeded 10 C, unprecedented in the overall record. Variation of sunspot cyclic averages and 2-cycle moving averages of temperature strongly associate with similar averages for the solar/geomagnetic cycle, with the residuals displaying an apparent 9-cycle variation and a steep rise in temperature associated with cycle 23. Hale cycle averages of temperature for even-odd pairs of sunspot cycles correlate against similar averages for the solar/geomagnetic cycle and, especially, against the length of the Hale cycle. Indications are that annual mean temperature will likely exceed 10 C over the next decade.

[Evaluation of the influence of humidity and temperature on the drug stability by initial average rate experiment].

PubMed

He, Ning; Sun, Hechun; Dai, Miaomiao

2014-05-01

To evaluate the influence of temperature and humidity on the drug stability by initial average rate experiment, and to obtained the kinetic parameters. The effect of concentration error, drug degradation extent, humidity and temperature numbers, humidity and temperature range, and average humidity and temperature on the accuracy and precision of kinetic parameters in the initial average rate experiment was explored. The stability of vitamin C, as a solid state model, was investigated by an initial average rate experiment. Under the same experimental conditions, the kinetic parameters obtained from this proposed method were comparable to those from classical isothermal experiment at constant humidity. The estimates were more accurate and precise by controlling the extent of drug degradation, changing humidity and temperature range, or by setting the average temperature closer to room temperature. Compared with isothermal experiments at constant humidity, our proposed method saves time, labor, and materials.

On the Trend of the Annual Mean, Maximum, and Minimum Temperature and the Diurnal Temperature Range in the Armagh Observatory, Northern Ireland, Dataset, 1844 -2012

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2013-01-01

Examined are the annual averages, 10-year moving averages, decadal averages, and sunspot cycle (SC) length averages of the mean, maximum, and minimum surface air temperatures and the diurnal temperature range (DTR) for the Armagh Observatory, Northern Ireland, during the interval 1844-2012. Strong upward trends are apparent in the Armagh surface-air temperatures (ASAT), while a strong downward trend is apparent in the DTR, especially when the ASAT data are averaged by decade or over individual SC lengths. The long-term decrease in the decadaland SC-averaged annual DTR occurs because the annual minimum temperatures have risen more quickly than the annual maximum temperatures. Estimates are given for the Armagh annual mean, maximum, and minimum temperatures and the DTR for the current decade (2010-2019) and SC24.

A Slag Management Toolset for Determining Optimal Coal Gasification Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwong, Kyei-Sing; Bennett, James P.

Abstract Gasifier operation is an intricate process because of the complex relationship between slag chemistry and temperature, limitations of feedstock materials, and operational preference. High gasification temperatures increase refractory degradation, while low gasification temperatures can lead to slag buildup on the gasifier sidewall or exit, either of which are problematic during operation. Maximizing refractory service life and gasifier performance require finding an optimized operating temperature range which is a function of the coal slag chemistry and viscosity. Gasifier operators typically use a slag’s viscosity-temperature relationship and/or ash-fusion fluid temperature to determine the gasification temperature range. NETL has built a slagmore » management toolset to determine the optimal temperature range for gasification of a carbon feedstock. This toolset is based on a viscosity database containing experimental data, and a number of models used to predict slag viscosity as a function of composition and temperature. Gasifier users typically have no scientific basis for selecting an operational temperature range for gasification, instead using experience to select operational conditions. The use of the toolset presented in this paper provides a basis for estimating or modifying carbon feedstock slags generated from ash impurities in carbon feedstock.« less

A Slag Management Toolset for Determining Optimal Coal Gasification Temperatures

DOE PAGES

Kwong, Kyei-Sing; Bennett, James P.

2016-11-25

Abstract Gasifier operation is an intricate process because of the complex relationship between slag chemistry and temperature, limitations of feedstock materials, and operational preference. High gasification temperatures increase refractory degradation, while low gasification temperatures can lead to slag buildup on the gasifier sidewall or exit, either of which are problematic during operation. Maximizing refractory service life and gasifier performance require finding an optimized operating temperature range which is a function of the coal slag chemistry and viscosity. Gasifier operators typically use a slag’s viscosity-temperature relationship and/or ash-fusion fluid temperature to determine the gasification temperature range. NETL has built a slagmore » management toolset to determine the optimal temperature range for gasification of a carbon feedstock. This toolset is based on a viscosity database containing experimental data, and a number of models used to predict slag viscosity as a function of composition and temperature. Gasifier users typically have no scientific basis for selecting an operational temperature range for gasification, instead using experience to select operational conditions. The use of the toolset presented in this paper provides a basis for estimating or modifying carbon feedstock slags generated from ash impurities in carbon feedstock.« less

Assessment of a full-scale duckweed pond system for septage treatment.

PubMed

Papadopoulos, F H; Tsihrintzis, V A

2011-01-01

Environmental conditions and wastewater treatment performance in a full-scale duckweed pond system are presented. The treatment system consisted of three stabilization ponds in series and was fed with septage. Vacuum trucks pumped the septage from residential holding tanks and discharged it to the system daily. The inflow rates averaged 36 m3 d(-1) in the cold season and 60 m3 d(-1) in the warm season. Duckweed (Lemna minor) colonized the ponds in the warm months and survived during the cold season. Because of the difficult process for harvesting the duckweed biomass, the investigation of the treatment efficiency was carried out without plant harvesting. Samples were collected from the vacuum trucks and from the exit of each pond and were analysed for physicochemical and microbiological parameters over a period of 12 months. The results showed that the duckweed mat suppressed algal biomass, which in turn led to anoxic and neutral pond conditions. On an annual basis, the duckweed system sufficiently removed BOD5 (94%), NH4+ (72%) and E. coli (99.65%), with lower removal of TSS (63%) and Enterococci (91.76%). A slight increase (1.1%) was recorded for o-PO4(3-). Between the two sampling seasons, BOD5 and TSS removal efficiencies were higher in the cold season with the longer retention time. Similar removal values in the warm and the cold season were found for nutrients and bacteria. These findings indicate that BOD5 and TSS removals are less temperature-dependent at higher retention times, while ammonia nitrogen and bacterial removals are substantially influenced by temperature as well as retention time.