WorldWideScience

Sample records for density temperature velocity

  1. Multi Point Velocity, Density and Temperature Measurements using LITA Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced thermal acoustics (LITA) is a nonintrusive, transient-grating optical technique that provides simultaneous high-accuracy measurements of velocity,...

  2. Preliminary measurements of velocity, density and total temperature fluctuations in compressible subsonic flow

    Science.gov (United States)

    Stainback, P. C.; Johnson, C. B.; Basnett, C. B.

    1983-01-01

    The heat transfer characteristics of a three-wire hot-wire probe operated with a constant temperature anemometer were investigated in the subsonic compressible flow regime. The sensitivity coefficients, with respect to velocity, density and total temperature, were measured and the results were used to calculate the velocity, density, and total temperature fluctuations in the test section of the Langley 0.3-m Transonic Cryogenic Tunnel (TCT). These results were extended to give estimates for fluctuations due to vorticity, sound, and entropy. In addition, attempts were made to determine the major source of disturbances in the 0.3-m TCT.

  3. Molecular Rayleigh Scattering Diagnostic for Dynamic Temperature, Velocity, and Density Measurements

    Science.gov (United States)

    Mielke, Amy R.; Elam, Kristie A.; Sung, Chi-Jen

    2006-01-01

    A molecular Rayleigh scattering technique is developed to measure dynamic gas temperature, velocity, and density in unseeded turbulent flows at sampling rates up to 16 kHz. A high power CW laser beam is focused at a point in an air jet plume and Rayleigh scattered light is collected and spectrally resolved. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. The circular interference fringe pattern is divided into four concentric regions and sampled at 1 and 16 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows for measurement of gas temperature and velocity. Independently monitoring the total scattered light intensity provides a measure of gas density. A low speed heated jet is used to validate the measurement of temperature fluctuations and an acoustically excited nozzle flow is studied to validate velocity fluctuation measurements. Power spectral density calculations of the property fluctuations, as well as mean and fluctuating quantities are presented. Temperature fluctuation results are compared with constant current anemometry measurements and velocity fluctuation results are compared with constant temperature anemometry measurements at the same locations.

  4. The role of riparian vegetation density, channel orientation and water velocity in determining river temperature dynamics

    Science.gov (United States)

    Garner, Grace; Malcolm, Iain A.; Sadler, Jonathan P.; Hannah, David M.

    2017-10-01

    A simulation experiment was used to understand the importance of riparian vegetation density, channel orientation and flow velocity for stream energy budgets and river temperature dynamics. Water temperature and meteorological observations were obtained in addition to hemispherical photographs along a ∼1 km reach of the Girnock Burn, a tributary of the Aberdeenshire Dee, Scotland. Data from nine hemispherical images (representing different uniform canopy density scenarios) were used to parameterise a deterministic net radiation model and simulate radiative fluxes. For each vegetation scenario, the effects of eight channel orientations were investigated by changing the position of north at 45° intervals in each hemispheric image. Simulated radiative fluxes and observed turbulent fluxes drove a high-resolution water temperature model of the reach. Simulations were performed under low and high water velocity scenarios. Both velocity scenarios yielded decreases in mean (≥1.6 °C) and maximum (≥3.0 °C) temperature as canopy density increased. Slow-flowing water resided longer within the reach, which enhanced heat accumulation and dissipation, and drove higher maximum and lower minimum temperatures. Intermediate levels of shade produced highly variable energy flux and water temperature dynamics depending on the channel orientation and thus the time of day when the channel was shaded. We demonstrate that in many reaches relatively sparse but strategically located vegetation could produce substantial reductions in maximum temperature and suggest that these criteria are used to inform future river management.

  5. Molecular Rayleigh Scattering Techniques Developed for Measuring Gas Flow Velocity, Density, Temperature, and Turbulence

    Science.gov (United States)

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

    2005-01-01

    Nonintrusive optical point-wise measurement techniques utilizing the principles of molecular Rayleigh scattering have been developed at the NASA Glenn Research Center to obtain time-averaged information about gas velocity, density, temperature, and turbulence, or dynamic information about gas velocity and density in unseeded flows. These techniques enable measurements that are necessary for validating computational fluid dynamics (CFD) and computational aeroacoustic (CAA) codes. Dynamic measurements allow the calculation of power spectra for the various flow properties. This type of information is currently being used in jet noise studies, correlating sound pressure fluctuations with velocity and density fluctuations to determine noise sources in jets. These nonintrusive techniques are particularly useful in supersonic flows, where seeding the flow with particles is not an option, and where the environment is too harsh for hot-wire measurements.

  6. Graphene, a material for high temperature devices; intrinsic carrier density, carrier drift velocity, and lattice energy

    CERN Document Server

    Yin, Yan; Wang, Li; Jin, Kuijuan; Wang, Wenzhong

    2016-01-01

    Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of ...

  7. Observations of the temperature, density and velocity structure of the solar corona

    Science.gov (United States)

    Osterman, Steven Neil

    1994-01-01

    The solar corona exists at a temperature of over 106 K while the underlying visible surface, the photosphere, is much cooler, about 6,000K. How this tenuous outer layer can be many orders of magnitude hotter than the photosphere is one of the principal enigmas of solar physics. Various mechanisms have been proposed to explain coronal heating, but none have been completely successful in accounting for its observed characteristics. It is the purpose of this thesis to present observations of both the large scale velocity structure and the small scale density and temperature structure of the quiet corona which will constrain theories of coronal heating. Spatially resolved spectra of the solar corona were obtained in the extreme ultraviolet during a sounding rocket experiment on June 20, 1989. In order to obtain an accurate photometric calibration of the spectrometer, we developed a new technique using a synchrotron radiation source operated by the National Institute for Standards and Technology. With this calibration, along with the high spectral resolution and on-board wavelength calibration capability of the payload, we were able to develop a detailed picture of the density and velocity structure of a portion of the solar corona. Data from the sounding rocket experiment were then compared to white light observations made by the Mk-3 coronagraph operated by the High Altitude Observatory at Mauna Loa. The white light continuum intensity of the solar corona is proportional to the mean electron density along the line of sight, whereas the emission line intensity is proportional to the average value of the electron density squared. By comparing these two data sets, we find that the density irregularity factor is close to unity for the quiet corona. The irregularity analysis in this thesis is the first to consider the possibility of a non-isothermal corona. We also find that the systematic velocity structure seen in the transition region is not present in the solar corona.

  8. Scaling of maximum probability density functions of velocity and temperature increments in turbulent systems

    CERN Document Server

    Huang, Y X; Zhou, Q; Qiu, X; Shang, X D; Lu, Z M; Liu, and Y L

    2014-01-01

    In this paper, we introduce a new way to estimate the scaling parameter of a self-similar process by considering the maximum probability density function (pdf) of tis increments. We prove this for $H$-self-similar processes in general and experimentally investigate it for turbulent velocity and temperature increments. We consider turbulent velocity database from an experimental homogeneous and nearly isotropic turbulent channel flow, and temperature data set obtained near the sidewall of a Rayleigh-B\\'{e}nard convection cell, where the turbulent flow is driven by buoyancy. For the former database, it is found that the maximum value of increment pdf $p_{\\max}(\\tau)$ is in a good agreement with lognormal distribution. We also obtain a scaling exponent $\\alpha\\simeq 0.37$, which is consistent with the scaling exponent for the first-order structure function reported in other studies. For the latter one, we obtain a scaling exponent $\\alpha_{\\theta}\\simeq0.33$. This index value is consistent with the Kolmogorov-Ob...

  9. A high speed data acquisition system for the analysis of velocity, density, and total temperature fluctuations at transonic speeds

    Science.gov (United States)

    Clukey, Steven J.; Jones, Gregory S.; Stainback, P. Calvin

    1988-01-01

    The use of a high-speed Dynamic Data Acquisition System (DDAS) to measure simultaneously velocity, density, and total temperature fluctuations is described. The DDAS is used to automate the acquisition of hot-wire calibration data. The data acquisition, data handling, and data reporting techiques used by DDAS are described. Sample data are used to compare results obtained with the DDAS with those obtained from the FM tape and post-test digitization method.

  10. Some influences of approximate values for velocity, density and total temperature sensitivities on hot wire anemometer results

    Science.gov (United States)

    Stainback, P. C.

    1986-01-01

    There is a renewed interest in hot wire anemometry at transonic speeds. Recent results were published which indicate that at transonic speeds a heated wire is sensitive only to mass flow and total temperature, results similar to those obtained for supersonic flows. Other results were obtained to show that the sensitivity is a function of velocity, density, and total temperature, results in agreement with many of those obtained in the 1950s. An analysis of anemometry results was made to evaluate possible errors when various assumptions were made concerning the sensitivity of a heated wire to fluid flow variables.

  11. Increase of the Density, Temperature and Velocity of Plasma Jets driven by a Ring of High Energy Laser Beams

    CERN Document Server

    Fu, Wen; Fatenejad, Milad; Lamb, Donald Q; Grosskopf, Michael; Park, Hye-Sook; Remington, Bruce; Spitkovsky, Anatoly

    2012-01-01

    Supersonic plasma outflows driven by multi-beam, high-energy lasers, such as Omega and NIF, have been and will be used as platforms for a variety of laboratory astrophysics experiments. Here we propose a new way of launching high density and high velocity, plasma jets using multiple intense laser beams in a hollow ring formation. We show that such jets provide a more flexible and versatile platform for future laboratory astrophysics experiments. Using high resolution hydrodynamic simulations, we demonstrate that the collimated jets can achieve much higher density, temperature and velocity when multiple laser beams are focused to form a hollow ring pattern at the target, instead of focused onto a single spot. We carried out simulations with different ring radii and studied their effects on the jet properties. Implications for laboratory collisionless shock experiments are discussed.

  12. Increase of the Density, Temperature and Velocity of Plasma Jets driven by a Ring of High Energy Laser Beams

    OpenAIRE

    Fu, Wen; Liang, Edison P.; Fatenejad, Milad; Lamb, Donald Q.; Grosskopf, Michael; Park, Hye-Sook; Remington, Bruce; Spitkovsky, Anatoly

    2012-01-01

    Supersonic plasma outflows driven by multi-beam, high-energy lasers, such as Omega and NIF, have been and will be used as platforms for a variety of laboratory astrophysics experiments. Here we propose a new way of launching high density and high velocity, plasma jets using multiple intense laser beams in a hollow ring formation. We show that such jets provide a more flexible and versatile platform for future laboratory astrophysics experiments. Using high resolution hydrodynamic simulations,...

  13. Development of a Rayleigh Scattering Diagnostic for Time-Resolved Gas Flow Velocity, Temperature, and Density Measurements in Aerodynamic Test Facilities

    Science.gov (United States)

    Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen

    2007-01-01

    A molecular Rayleigh scattering technique is developed to measure time-resolved gas velocity, temperature, and density in unseeded turbulent flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultiplier tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. An acoustically driven nozzle flow is studied to validate velocity fluctuation measurements, and an asymmetric oscillating counterflow with unequal enthalpies is studied to validate the measurement of temperature fluctuations. Velocity fluctuations are compared with constant temperature anemometry measurements and temperature fluctuations are compared with constant current anemometry measurements at the same locations. Time-series and power spectra of the temperature and velocity measurements are presented. A numerical simulation of the light scattering and detection process was developed and compared with experimental data for future use as an experiment design tool.

  14. Weakly nonlinear density-velocity relation

    CERN Document Server

    Chodorowski, M J; Chodorowski, Michal J; Lokas, Ewa L

    1996-01-01

    We rigorously derive weakly nonlinear relation between cosmic density and velocity fields up to third order in perturbation theory. The density field is described by the mass density contrast, \\de. The velocity field is described by the variable \\te proportional to the velocity divergence, \\te = - f(\\Omega)^{-1} H_0^{-1} \

  15. Comparison of H-mode plasma simulations using toroidal velocity models depending on plasma current density and ion temperature in presence of an ITB

    Directory of Open Access Journals (Sweden)

    Boonyarit Chatthong

    2014-06-01

    Full Text Available Two different approaches for predicting plasma toroidal velocity (v are developed and used in self-consistent simulations of H-mode plasmas with the presence of ITB using BALDUR integrated predictive modelling code. In the first approach, the toroidal velocity depends on the plasma current density; while in the second approach the toroidal velocity is directly proportional to the ion temperature. The profile of v is used to calculate the ExB flow shear which is a main mechanism for plasma transport suppression, leading to the ITB formation. In all simulations, the core transport model is a combination of NCLASS neoclassical transport and semi-empirical Mixed Bohm/gyro-Bohm model that includes the ITB effects. The boundary condition is set at top of the pedestal and is estimated using a pedestal model based on a combination of magnetic and flow shear stabilization pedestal width scaling and an infinite-n ballooning pressure gradient. Two toroidal velocity models are used to simulate the time evolution of plasma temperature and density profiles of 10 JET discharges. The root mean square error (RMSE is used to compare simulation results of those 10 JET discharges with experimental data. It is found that RMSE of Ti , Te , ne are 28.1%, 31.8%, and 15.0% for the first toroidal velocity model and 25.5%, 30.2%, and 15.1% for the second toroidal velocity model, respectively. Furthermore, this suite of codes is used to predict the ITER performance under standard type I ELMy H-mode. It is found that the simulation yields formation of a narrow ITB near r/a = 0.7 in the simulation using the current density dependent model and a wide ITB from r/a = 0.5 to 0.8 in the simulation using the ion temperature dependent model. The average of central ion temperature, total fusion power output and alpha power are predicted to be 36 keV, 159 MW and 492 MW for the current density dependent model and 49 keV, 218 MW and 786 MW for the ion temperature dependent

  16. Analytic representations of high-altitude auroral H^+ and O^+ densities, flow velocities and temperatures in terms of drivers for incorporation into global magnetospheric models

    Science.gov (United States)

    Horwitz, James; Zeng, Wen

    2008-10-01

    As new methods of describing multiple fluid species and other advances enhance the capability of global magnetospheric models to simulate the dynamics of multiple ion species, they also allow more accurate incorporation of ionospheric plasma outflows as source populations into these large scale models. Here, we shall describe the distilled results of numerous physics-based simulations of ionospheric plasma outflows influenced by auroral driving agents in terms of compact analytic expressions in terms of precipitation electron energy flux levels, characteristic energy levels of the precipitating electrons, the peak spectral wave densities for low-frequency electrostatic waves which transversely heat ionospheric ions, and solar zenith angle. The simulations are conducted with the UT Arlington Dynamic Fluid Kinetic (DyFK) ionospheric plasma transport code. We present these analytic expressions for ionospheric origin O^+ and H^+ densities, temperatures and field-aligned flow velocities at the 3 RE altitude inner boundaries of typical magnetospheric models.

  17. VELOCITY OF DETONATION OF LOW DENSITY

    Directory of Open Access Journals (Sweden)

    Vinko Škrlec

    2012-12-01

    Full Text Available Blasting operations in built-up areas, at short distances from structures, impose new requirements on blasting techniques and properties of explosives in order to mitigate seismic effect of blasting. Explosives for civil uses are mixtures of different chemical composition of explosive and/or non-explosive substances. Chemical and physical properties, along with means of initiation, environment and the terms of application define detonation and blasting parameters of a particular type of the explosive for civil uses. Velocity of detonation is one of the most important measurable characteristics of detonation parameters which indirectly provide information about the liberated energy, quality of explosives and applicability for certain purposes. The level of shock effect of detonated charge on the rock, and therefore the level of seismic effect in the area, depends on the velocity of detonation. Since the velocity of detonation is proportional to the density of an explosive, the described research is carried out in order to determine the borderline density of the mixture of an emulsion explosive with expanded polystyrene while achieving stable detonation, and to determine the dependency between the velocity of detonation and the density of mixture (the paper is published in Croatian.

  18. Diffusion and butterfly velocity at finite density

    Science.gov (United States)

    Niu, Chao; Kim, Keun-Young

    2017-06-01

    We study diffusion and butterfly velocity ( v B ) in two holographic models, linear axion and axion-dilaton model, with a momentum relaxation parameter ( β) at finite density or chemical potential ( μ). Axion-dilaton model is particularly interesting since it shows linear- T -resistivity, which may have something to do with the universal bound of diffusion. At finite density, there are two diffusion constants D ± describing the coupled diffusion of charge and energy. By computing D ± exactly, we find that in the incoherent regime ( β/T ≫ 1 , β/μ ≫ 1) D + is identified with the charge diffusion constant ( D c ) and D - is identified with the energy diffusion constant ( D e ). In the coherent regime, at very small density, D ± are `maximally' mixed in the sense that D +( D -) is identified with D e ( D c ), which is opposite to the case in the incoherent regime. In the incoherent regime D e ˜ C - ℏv B 2 / k B T where C - = 1 /2 or 1 so it is universal independently of β and μ. However, {D}_c˜ {C}+\\hslash {v}{^B}^2/{k}_BT where C + = 1 or β 2 /16 π 2 T 2 so, in general, C + may not saturate to the lower bound in the incoherent regime, which suggests that the characteristic velocity for charge diffusion may not be the butterfly velocity. We find that the finite density does not affect the diffusion property at zero density in the incoherent regime.

  19. Physics-based formula representations of high-latitude ionospheric outflows: H+ and O+ densities, flow velocities, and temperatures versus soft electron precipitation, wave-driven transverse heating, and solar zenith angle effects

    Science.gov (United States)

    Horwitz, J. L.; Zeng, W.

    2009-01-01

    Extensive systematic dynamic fluid kinetic (DyFK) model simulations are conducted to obtain advanced simulation-based formula representations of ionospheric outflow parameters, for possible use by global magnetospheric modelers. Under F10.7 levels of 142, corresponding to solar medium conditions, we obtain the H+ and O+ outflow densities, flow velocities, and perpendicular and parallel temperatures versus energy fluxes and characteristic energies of soft electron precipitation, wave spectral densities of ion transverse wave heating, and F region level solar zenith angle in the high-latitude auroral region. From the results of hundreds of DyFK simulations of auroral outflows for ranges of each of these driving agents, we depict the H+ and O+ outflow density and flow velocity parameters at 3 R E altitude at the ends of these 2-h simulation runs in spectrogram form versus various pairs of these influencing parameters. We further approximate these results by various distilled formula representations for the O+ and H+ outflow velocities, densities, and temperatures at 3 R E altitude, as functions of the above indicated four ``driver'' parameters. These formula representations provide insight into the physics of these driven outflows, and may provide a convenient set of tools to set the boundary conditions for ionospheric plasma sources in global magnetospheric simulations.

  20. The Hatteras Front: August 2004 velocity and density structure

    Science.gov (United States)

    Savidge, Dana K.; Austin, Jay A.

    2007-07-01

    The Hatteras Front is a persistent mesoscale cross-shelf oriented front off Cape Hatteras, North Carolina. It is the boundary between relatively cool, fresh Mid-Atlantic Bight shelf waters and warmer, saltier shelf waters of the South Atlantic Bight, which both converge along-shelf upon Cape Hatteras year round. The Frontal Interaction Near Cape Hatteras (FINCH) project was conducted in 2004-2005 to intensively sample the Hatteras Front with shipboard ADCP and undulating towed CTD. This paper documents velocity and density structures associated with the cross-shelf oriented zone of Hatteras Front during the August 2004 field season. Property gradients across the Hatteras Front are large, with temperature (T) and salinity (S) differences of ˜4-6°C, 2-5 psu, respectively over distances of 1-2 km. The T and S are not completely compensating, and a strong density (ρ) gradient also exists, with Δρ of ˜2 kg/m3 across a gentler 10 km wide front. The density gradient results in a steric sea-level height gradient of ˜1-2 cm across the Front, which is in approximate geostrophic balance with a surface intensified jet, directed shoreward along the cross-shelf oriented Front. The velocity is sheared with depth at 3.0 × 10-2 to 5.0 × 10-2 s-1 in the upper 5 m of the jet; a rate consistent with the density gradient according to the thermal wind relationship. Shoreward transport of ˜4.8 × 104 m3/s results from the surface intensified jet. The structure of the velocity field associated with the Hatteras Front resembles that of a slope-controlled buoyant plume, as described by Lentz and Helfrich (2002). Velocity and density structures are similar during both advancing (southwestward) and retreating (northeastward) motion of the Front.

  1. (AJST) ON THE PRESSURE VELOCITY AND TEMPERATURE ...

    African Journals Online (AJOL)

    the pressure and fluid velocity are average over the ... describing the flow are sets of nonlinear first-order ... resemble those of the one-dimensional gas dynamics. [5]. .... blood constituents (solid corpuscles and plasma) flow ... where ρ is the varying fluid density, u axial fluid ..... (1989): Biofluid mechanics, Annual review fluid.

  2. Late Quaternary temperature change velocity in Mesoamerica

    Science.gov (United States)

    Correa-Metrio, A.; Lozano, S.; Sosa-Nájera, S.; Bush, M. B.

    2013-05-01

    Quaternary climate has been highly variable, and yet few quantitative continental reconstructions are available for tropical areas. Quantitative records of temperature change during the Quaternary are especially relevant for putting modern climate change into a historic context. Within this perspective, two aspects are of singular relevance: i) Identifying and quantifying past climatic variability, and ii) Providing a means to estimate the seed at which climate change happened in the past. Here we show temperature reconstructions and temperature change velocity calculations for two locations in northern tropical America. Temperature reconstruction was based on two sedimentary records form Lake Chalco (30,000 years), central Mexican highlands, and Lake Petén-Itzá, Guatemalan lowlands (86,000 years). Temperature reconstruction was based on the analysis of fossil pollen on the light of pollen-temperature transfer functions. These functions were calibrated through an extensive survey of modern pollen samples covering an elevational gradient from 0 to 4,218 m asl. Derived temperature profiles show a parallel long-term trend and a similar cooling of approximately 5 oC during the Last Glacial Maximum in the lowlands and highlands of Mexico and Guatemala. Using a digital elevation model, we ere able to reconstruct the velocity at which isotherms displaced to produce the observed temperature anomalies. Spatial velocities of temperature change in the studied areas were at least four times slower than values reported for the last 50 years, but also at least twice as fast as those obtained from recent models. This study demonstrates that modern temperature change has no precedent within the last 86,000 years, but also that tropical climate has been more variable than it has been assumed to date.

  3. Toward a self-consistent pressure scale: elastic moduli and equation of state of MgO by simultaneous x-ray density and Brillouin sound velocity measurements at high-pressure high-temperature conditions

    Science.gov (United States)

    Sinogeikin, S. V.; Lakshtanov, D. L.; Prakapenka, V. B.; Sanchez-Valle, C.; Wang, J.; Chen, B.; Shen, G.; Bass, J. D.

    2007-12-01

    Accurate phase diagrams and PVT equations of state (EOS) of materials strongly depend on the PVT calibrations of standard materials (e.g. MgO, NaCl, Au, Pt), which currently do not predict identical pressures at the same experimental conditions. MgO is commonly used as a pressure standard in a variety of high pressure and high- temperature experiments. Despite being one of the simplest and most studied materials, its accurate EOS is still uncertain, especially at high PT. The direct way of obtaining a self consistent pressure scale is by measuring acoustic velocities (Vp and Vs) and density simultaneously. Such P-V-T-Vp-Vs measurements allow one to determine the pressure directly, without resort to a separate calibration standard. Recently, as part of a major COMPRES initiative, we have constructed a Brillouin spectrometer at GSECARS, APS (13-BM-D) which allows accurate simultaneous sound velocity and lattice parameter measurements at high pressures and high temperatures. Such measurements were performed on single crystal MgO at simultaneously high pressures (up to 30 GPa) and high temperatures (up to 873K) in diamond cells with Ne or Ar as pressure medium. At each PT point we measured the unit cell parameters and the acoustic velocities of MgO in several crystallographic directions, and directly obtained all three single crystal elastic moduli, as well as isotropic adiabatic bulk (KS) and shear (μ) moduli. Unit cell parameters of pressure medium (Ne, Ar) and additional pressure calibrants (Au, Pt, NaCl) were measured at each PT for cross calibration. The results of these experiments and implications for a self consistent P-V-T(-Vp-Vs) pressure scale will be presented and discussed.

  4. Toward a self-consistent pressure scale: elastic moduli and equation of state of MgO and Ringwoodite by simultaneous x-ray density and Brillouin sound velocity measurements at high-pressure high-temperature conditions

    Science.gov (United States)

    Sinogeikin, S.; Lakshtanov, D.; Prakapenka, V.; Sanchez-Valle, C.; Wang, J.; Shen, G.; Bass, J.

    2009-05-01

    Accurate phase diagrams and PVT equations of state (EOS) of materials strongly depend on the PVT calibrations of standard materials (e.g. MgO, NaCl, Au, Pt), which currently do not predict identical pressures at the same experimental conditions. MgO is commonly used as a pressure standard in a variety of high pressure and high-temperature experiments. Despite being one of the simplest and most studied materials, its accurate EOS is still uncertain, especially at high PT. The direct way of obtaining a self consistent pressure scale is by measuring acoustic velocities (Vp and Vs) and density simultaneously. Such P-V-T-Vp-Vs measurements allow one to determine the pressure directly, without resort to a separate calibration standard. Recently, as part of a major COMPRES initiative, we have constructed a Brillouin spectrometer at GSECARS, APS (13-BM-D) which allows accurate simultaneous sound velocity and lattice parameter measurements at high pressures and high temperatures. Such measurements were performed on single crystal MgO at simultaneously high pressures (up to 30 GPa) and high temperatures (up to 873K) in diamond cells. At each PT point we measured the unit cell parameters and the acoustic velocities of MgO in several crystallographic directions, and directly obtained all three single crystal elastic moduli, as well as isotropic adiabatic bulk (Ks) and shear (μ) moduli. Unit cell parameters of pressure medium (Ne, Ar) and additional pressure calibrants (Au, Pt, NaCl) were measured at each PT for cross calibration. In addition we demonstrate that successful P-V-T-Vp-Vs measurements can be performed on certain polycrystalline materials, e.g. Ringwoodite (γ-Mg2SiO4). The results of these experiments and implications for a self consistent P-V-T(-Vp-Vs) pressure scale will be presented and discussed.

  5. Understanding redshift space distortions in density-weighted peculiar velocity

    CERN Document Server

    Sugiyama, Naonori S; Spergel, David N

    2015-01-01

    Observations of the kinetic Sunyaev-Zel'dovich (kSZ) effect measure the density-weighted velocity field, a potentially powerful cosmological probe. This paper presents an analytical method to predict the power spectrum and two-point correlation function of the density-weighted velocity in redshift space, the direct observables in kSZ surveys. We show a simple relation between the density power spectrum and the density-weighted velocity power spectrum that holds for both dark matter and halos. Using this relation, we can then extend familiar perturbation expansion techniques to the kSZ power spectrum. One of the most important features of the density-weighted velocity is the change of the sign of infall velocity at small scales due to the nonlinear redshift space distortion. Our model can explain this characteristic feature without any free parameters. As a result, our results can precisely predict the non-linear behavior of the density-weighted velocity field in redshift space up to $\\sim10\\ h^{-1} {\\rm Mpc}$...

  6. Density dependence of the saturated velocity in graphene

    Science.gov (United States)

    Ferry, D. K.

    2016-11-01

    The saturated velocity of a semiconductor is an important measure in bench-marking performance for either logic or microwave applications. Graphene has been of interest for such applications due to its apparently high value of the saturated velocity. Recent experiments have suggested that this value is very density dependent and can even exceed the band limiting Fermi velocity. Some of these measurements have also suggested that the scattering is dominated by the low energy surface polar mode of the SiO2 substrate. Here, we show that the saturated velocity of graphene on SiO2 is relatively independent of the density and that the scattering is dominated by the high energy surface polar mode of the substrate.

  7. Density Models for Velocity Analysis of Jet Impinged CEDM Missile

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Won Ho; Kang, Tae Kyo; Cho, Yeon Ho; Chang, Sang Gyoon; Lee, Dae Hee [KEPCO EnC, Daejeon (Korea, Republic of)

    2015-05-15

    A control element drive mechanism (CEDM) can be a potential missile in the reactor head area during one of the postulated accidents. The CEDM is propelled by the high speed water jet discharged from a broken upper head nozzle. The jet expansion models to predict the missile velocity have been investigated by Kang et al. The previous work of Kang et al. showed a continuous increase in missile velocity as the CEDM missile travels. But it is not natural in that two phase flow from the nozzle break exit tends to disperse and the thrust force on the missile decreases along the distance of the travel. The jet flow also interacts with the air surrounding itself. Therefore, the density change has to be included in the estimation of the missile velocity. In this paper, two density change models of the water jet are introduced for the jet expansion models along with the distance from the nozzle break location. The first one is the direct approximation model. Two density approximation models are introduced to predict the CEDM missile velocity. For each model, the effects of the expanded jet area were included as the area ratio to the exit nozzle area. In direct approximation model, the results have showed rapid decrease in both density and missile velocity. In pressure approach model, the density change is assumed perfectly proportional to the pressure change, and the results showed relatively smooth change in both density and missile velocity comparing to the direct approximation model. Using the model developed by Kang et al.., the maximum missile velocity is about 4 times greater comparing to the pressure approach model since the density is constant as the jet density at the nozzle exit in their model. Pressure approach model has benefits in that this model adopted neither curve fitting nor extrapolation unlike the direct approximation model, and included the effects of density change which are not considered in the model developed by Kang et al. So, this model is

  8. The weakly non-linear density-velocity relation

    Science.gov (United States)

    Chodorowski, Michal J.; Lokas, Ewa L.

    1997-05-01

    We rigorously derive up to third order in perturbation theory the weakly non-linear relation between the cosmic density and velocity fields. The density field is described by the mass density contrast, delta. The velocity field is described by the variable theta proportional to the velocity divergence, theta=-f (Omega)^-1H ^-1_0∇. v, where f (Omega)~=Omega^0.6, Omega is the cosmological density parameter and H_0 is the Hubble constant. Our calculations show that mean delta given theta is a third-order polynomial in theta, --_theta=a _1theta+a_2(theta ^2-sigma^2_theta)+ a_3theta^3. This result constitutes an extension of the formula --_theta=theta+a _2(theta^2-sigma^2 _theta) found by Bernardeau which involved second-order perturbative solutions. Third-order perturbative corrections introduce the cubic term. They also, however, cause the coefficient a_1 to depart from unity, in contrast with the linear theory prediction. We compute the values of the coefficients a_p for scale-free power spectra, as well as for standard cold dark matter (CDM), for Gaussian smoothing. The coefficients obey a hierarchy a_3Ganon et al. The results provide a method for breaking the Omega-bias degeneracy in comparisons of cosmic density and velocity fields such as IRAS-potent.

  9. Velocity statistics from spectral line data effects of density-velocity correlations, magnetic field, and shear

    CERN Document Server

    Esquivel, A; Pogosyan, D; Cho, J; Esquivel, Alejandro; Cho, Jungyeon

    2003-01-01

    In a previous work Lazarian and Pogosyan suggested a technique to extract velocity and density statistics, of interstellar turbulence, by means of analysing statistics of spectral line data cubes. In this paper we test that technique, by studying the effect of correlation between velocity and density fields, providing a systematic analysis of the noise, and exploring the effect of a linear shear. We make use of both compressible MHD simulations and synthetic data to emulate spectroscopic observations. With such synthetic spectroscopic data, we studied anisotropies of the two point statistics and related those anisotropies with the magnetic field direction. This presents a new technique for magnetic field studies. The results show that the velocity and density spectral indices measured are consistent with the analytical predictions. We identified the dominant source of error with the limited number of data points along a given line of sight. We argue that in real observations the number of emmiting elements is...

  10. Simultaneous Temperature and Velocity Diagnostic for Reacting Flows Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A diagnostic technique is proposed for measuring temperature and velocity simultaneously in a high temperature reacting flow for aiding research in propulsion. The...

  11. Dark Matter Halos: Velocity Anisotropy -- Density Slope Relation

    CERN Document Server

    Zait, Amir; Shlosman, Isaac

    2007-01-01

    Dark matter (DM) halos formed in CDM cosmologies seem to be characterized by a power law phase-space density profile. The density of the DM halos is often fitted by the NFW profile but a better fit is provided by the Sersic fitting formula. These relations are empirically derived from cosmological simulations of structure formation but have not yet been explained on a first principle basis. Here we solve the Jeans equation under the assumption of a spherical DM halo in dynamical equilibrium, that obeys a power law phase space density and either the NFW-like or the Sersic density profile. We then calculate the velocity anisotropy, beta(r), analytically. Our main result is that for the NFW-like profile the beta - gamma relation is not a linear one (where gamma is the logarithmic derivative of the density rho[r]). The shape of beta(r) depends mostly on the ratio of the gravitational to kinetic energy within the NFW scale radius R_s. For the Sersic profile a linear beta - gamma relation is recovered, and in parti...

  12. The velocity-density relation in the spherical model

    CERN Document Server

    Bilicki, Maciej

    2008-01-01

    We study the cosmic velocity-density relation using the spherical collapse model (SCM) as a proxy to non-linear dynamics. Although the dependence of this relation on cosmological parameters is known to be weak, we retain the density parameter Omega_m in SCM equations, in order to study the limit Omega_m -> 0. We show that in this regime the considered relation is strictly linear, for arbitrary values of the density contrast, on the contrary to some claims in the literature. On the other hand, we confirm that for realistic values of Omega_m the exact relation in the SCM is well approximated by the classic formula of Bernardeau (1992), both for voids (delta<0) and for overdensities up to delta ~ 3. Inspired by this fact, we find further analytic approximations to the relation for the whole range delta from -1 to infinity. Our formula for voids accounts for the weak Omega_m-dependence of their maximal rate of expansion, which for Omega_m < 1 is slightly smaller that 3/2. For positive density contrasts, we ...

  13. Density profiles of dark matter halos with anisotropic velocity tensors

    CERN Document Server

    Hiotelis, N

    2002-01-01

    We present density profiles, that are solutions of the spherical Jeans equation, derived under the following two assumptions: (i) the coarse grained phase-density follows a power-law of radius, rho/(sigma^3) proportional to r^{-alpha}, and (ii) the velocity anisotropy parameter is given by the relation beta_a(r) = beta_1 + 2 beta_2 {(r/r_*)/(1+(r/r_*)^2)} where beta_1, beta_2 are parameters and r_* equals twice the virial radius, r_{vir}, of the system. These assumptions are well motivated by the results of N-body simulations. Density profiles have increasing logarithmic slopes gamma, defined by gamma = - {(d ln rho)/(d ln r)}. The values of gamma at r = 10^{-2.5}r_{vir}, a distance where the systems could be resolved by large N-body simulations, lie in the range 1. - 1.6. These inner values of gamma increase for increasing beta_1 and for increasing concentration of the system. On the other hand, slopes at r = r_{vir} lie in the range 2.42 - 3.82. A model density profile that fits well the results at radial d...

  14. Simultaneous temperature and velocity Lagrangian measurements in turbulent thermal convection

    CERN Document Server

    Liot, O; Zonta, F; Chibbaro, S; Coudarchet, T; Gasteuil, Y; Pinton, J -F; Salort, J; Chillà, F

    2015-01-01

    We report joint Lagrangian velocity and temperature measurements in turbulent thermal convection. Measurements are performed using an improved version (extended autonomy) of the neutrally-buoyant instrumented particle that was used by to performed experiments in a parallelepipedic Rayleigh-Benard cell. The temperature signal is obtained from a RFtransmitter. Simultaneously, we determine particle's position and velocity with one camera, which grants access to the Lagrangian heat flux. Due to the extended autonomy of the present particle, we obtain well converged temperature and velocity statistics, as well as pseudo-eulerian maps of velocity and heat flux. Present experimental results have also been compared with the results obtained by a corresponding campaign of Direct Numerical Simulations and Lagrangian Tracking of massless tracers. The comparison between experimental and numerical results show the accuracy and reliability of our experimental measurements. Finally, the analysis of lagrangian velocity and t...

  15. Internal wave pressure, velocity, and energy flux from density perturbations

    CERN Document Server

    Allshouse, Michael R; Morrison, Philip J; Swinney, Harry L

    2016-01-01

    Determination of energy transport is crucial for understanding the energy budget and fluid circulation in density varying fluids such as the ocean and the atmosphere. However, it is rarely possible to determine the energy flux field $\\mathbf{J} = p \\mathbf{u}$, which requires simultaneous measurements of the pressure and velocity perturbation fields, $p$ and $\\mathbf{u}$. We present a method for obtaining the instantaneous $\\mathbf{J}(x,z,t)$ from density perturbations alone: a Green's function-based calculation yields $p$, and $\\mathbf{u}$ is obtained by integrating the continuity equation and the incompressibility condition. We validate our method with results from Navier-Stokes simulations: the Green's function method is applied to the density perturbation field from the simulations, and the result for $\\mathbf{J}$ is found to agree typically to within $1\\%$ with $\\mathbf{J}$ computed directly using $p$ and $ \\mathbf{u}$ from the Navier-Stokes simulation. We also apply the Green's function method to densit...

  16. Digital technique for the simultaneous measurement of velocity and temperature.

    Science.gov (United States)

    Keffer, J F; Budny, R S; Kawall, J G

    1978-09-01

    A computer-oriented, hot-wire anemometer technique for the simultaneous measurement of velocity and temperature in heated turbulent flows is described. This technique involves conversion of analogue anemometer voltage signals into digital forms and processing of these latter on a digital computer, in accordance with the anemometer response equations, to obtain instantaneous temperature and velocity. The technique was tested with a heated plane jet and found to be satisfactory.

  17. Imaging density and seismic velocities in the Eastern Mediterranean

    Science.gov (United States)

    Blom, Nienke; Gokhberg, Alexey; Fichtner, Andreas

    2017-04-01

    The Mediterranean domain is a geologically complicated region, a result of its complex tectonic and geodynamic evolution. Our understanding of it draws from surface geology, modeling and imaging of the subsurface. Here, we present the first results of seismic waveform inversion of the Eastern Mediterranean region. While computationally much more expensive than more traditional ray-based imaging methods, the advantage of waveform tomography lies in its ability to incorporate in a consistent manner all the information in seismograms - not just the arrivals of certain, specified phases. As a result, body and multimode surface waves, source effects, frequency-dependence, wavefront healing, anisotropy and attenuation are naturally and coherently incorporated. This not only allows us to image P- and S-wave velocity jointly for the crust and mantle, but also makes it possible to put additional constraints on density that ray tomography cannot provide. This is of special interest because heterogeneities in density drive geodynamics, and the combined knowledge of all parameters would help to distinguish between thermal and compositional effects in the subsurface, where no direct measurements can be made. Our tomography makes use of a multi-scale approach, initially using only the very lowest frequency signals of periods of around 100-150 seconds which corresponds to structures of 200 km size in the crust. Slowly, higher-frequency data is added as the model is updated and more of the data is explained by it. Our ultimate aim is to go down to periods of 10 seconds, which corresponds to structures of about 15 km size in the crust to 25 km in the mantle. Only those parts of the seismograms are used in which data and synthetics are similar enough to allow for meaningful comparison. As iterations progress and synthetics become more similar to the data, more parts of the seismogram can be included. Resolution of the final model is assessed using a resolution analysis strategy

  18. Laboratory measurement of longitudinal wave velocity of artificial gas hydrate under different temperatures and pressures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The longitudinal wave velocity and attenuation measurements of artificial gas hy- drate samples at a low temperature are reported. And the temperature and pressure dependence of longitudinal wave velocity is also investigated. In order to under- stand the acoustic properties of gas hydrate, the pure ice, the pure tetrahydrofuran (THF), the pure gas hydrate samples and sand sediment containing gas hydrate are measured at a low temperature between 0℃ and –15℃. For the pure ice, the pure THF and the pure gas hydrate samples, whose density is 898 kg/m3, 895 kg/m3 and 475 kg/m3, the velocity of longitudinal wave is respectively 3574 m/s, 3428 m/s and 2439 m/s. For synthesized and compacted samples, the velocity of synthesized samples is lower than that of compacted samples. The velocities increase when the densities of the samples increase, while the attenuation decreases. Under the con- dition of low temperature, the results show that the velocity is slightly affected by the temperature. The results also show that wave velocities increase with the in- crease of piston pressures. For example, the velocity of one sample increases from 3049 up to 3337 m/s and the other increases from 2315 up to 2995 m/s. But wave velocity decreases from 3800 to 3546 m/s when the temperature increases from –15℃ to 5℃ and changes significantly close to the melting point. Formation con- ditions of the two samples are the same but with different conversion ratios of wa- ter. The results of the experiment are important for exploration of the gas hydrate resources and development of acoustic techniques.

  19. Velocity dispersions and X-ray temperatures of galaxy clusters

    CERN Document Server

    Girardi, M; Giuricin, G; Mardirossian, F; Mezzetti, M; Biviano, A

    1995-01-01

    Using a large and well-controlled sample of clusters of galaxies, we investigate the relation between cluster velocity dispersions and X-ray temperatures of intra-cluster gas. In order to obtain a reliable estimate of the total velocity dispersion of a cluster, independent of the level of anisotropies in galaxy orbits, we analyze the integrated velocity dispersion profiles over increasing distances from the cluster centers. Distortions in the velocity fields, the effect of close clusters, the presence of substructures, and the presence of a population of (spiral) galaxies not in virial equilibrium with the cluster potential are taken into account. Using our final sample of 37 clusters, for which a reliable estimate of the velocity dispersion could be obtained, we derive a relation between the velocity dispersions and the X-ray temperatures, with a scatter reduced by more than 30 % with respect to previous works. A chi square fit to the temperature-velocity dispersion relation does not exclude the hypothesis t...

  20. Gas velocity and temperature near a liquid rocket injector face

    Science.gov (United States)

    Boylan, D. M.; Ohara, J.

    1973-01-01

    The gas flow near the injector of a liquid propellant rocket was investigated by rapidly inserting butt-welded platinum-platinum rhodium thermocouples through the injector into the chamber. The transient responses of the thermocouples were analyzed to determine average gas temperatures and velocities. A method of fitting exponential curves to repeated measurements of the transient temperature at several positions near the injector face produced consistent results. Preliminary tests yielded gas flow directions and gas compositions at the injector face. Average gas temperatures were found to be between 3100 (1700) and 3500 F (1950 C) and the average gas velocities between 550 (170) and 840 feet/second (260 m/sec).

  1. Numerical simulation of temperature and velocity fields in plasma spray

    Institute of Scientific and Technical Information of China (English)

    FAN Qun-bo; WANG Lu; WANG Fu-chi

    2007-01-01

    Based on the turbulence jet model, with respect to Ar-He mixture plasma gas injecting to ambient atmosphere, the temperature filed and velocity field under typical working conditions were investigated. Given the conditions of I=900 A, FAr=1.98 m3/h, FHe=0.85 m3/h, it is found that both the temperature and the velocity undergo a plateau region near the nozzle exit (0-10 mm) at the very first stage, then decrease abruptly from initial 13 543 K and 778.2 m/s to 4 000 K and 260.0 m/s, and finally decrease slowly again. Meanwhile, the radial temperature and radial velocity change relatively slow. The inner mechanism for such phenomena is due to the complex violent interaction between the high-temperature and high-velocity turbulent plasma jet and the ambient atmosphere. Compared with traditional methods, the initial working conditions can be directly related to the temperature and velocity fields of the plasma jet by deriving basic boundary conditions.

  2. Effects of solid inertial particles on the velocity and temperature statistics of wall bounded turbulent flow

    DEFF Research Database (Denmark)

    Nakhaei, Mohammadhadi; Lessani, B.

    2016-01-01

    The effect of solid inertial particles on the velocity and temperature statistics of a non-isothermal turbulentchannel flow is studied using direct numerical simulation. The particles inertia is varied by changingthe particles diameter. The density of particles is kept constant. A two-way coupled...

  3. Compositional trends among Kaapvaal Craton garnet peridotite xenoliths and their effects on seismic velocity and density

    DEFF Research Database (Denmark)

    Schutt, Derek; Lesher, Charles

    2010-01-01

    garnet and clinopyroxene enrichment. Using the parameterization of Schutt and Lesher (2006) we show that at cratonic mantle temperatures and pressures, orthopyroxene enrichment results in little change in bulk density (ρbulk) and shear-wave velocity (VS), but decreases compressional wave velocities (VP...... and clinopyroxene enrichment possibly as a consequence of melt infiltration. More than half of the mineral mode variance among Kaapvaal Craton xenoliths can be accounted for by opx enrichment. Melt depletion effects can account for as much as 30% of the variance, while less than 20% of the variance is associated......) and VP/VS. In contrast, melt depletion has little effect on VP, but leads to an increase in VS and a decrease in ρbulk and VP/VS. Garnet (gt) and clinopyroxene (cpx) enrichment cause an increase in ρbulk, VP, VS, and VP/VS. The isolation of the major contributions to xenolith compositional variations...

  4. Correction of sound velocity depending on the temperature for unconsolidated marine sediment

    Science.gov (United States)

    Kim, Dae-Choul

    2016-04-01

    laboratory sound velocity measurements with systematic temperature change on unconsolidated marine sediment have been performed to establish the precise correction curves between temperature and the sound velocity. Piston and box core samples recovered from the East Sea and the South Sea of Korea were used for the measurement. The core samples were cooled (at temperature of nearly 0℃) and the temperature was gradually increased (from 0℃ to 30℃) to measure sound velocity depending on the changes in temperature. The sediment texture and physical properties (porosity, water content, and bulk density) were measured separately at the same depth. The rate of velocity increase for muddy, silty, and sandy sediment are about 2.63 m/s/℃, 2.74 m/s/℃, and 2.96 m/s/℃, respectively. This is similar to the velocity change rate, 2.97 m/s/℃ presented by Del Grosso (1952). The samples used in this research, however, have relatively higher porosity than those of Del Grosso (1952). Thus, the possibility of discrepancy is differences in water content which affect the sound velocity and measurement system. We used recently developed digital velocity measurement system using PXI based on LabVIEW. We suggest to employ this correction for the accurate in situ geoacoustic property from laboratory data particularly for the deep cold water sample such as the East Sea sediment that has very low bottom water temperature about 0℃. Keywords : in situ geoacoustic property, temperature correction, East Sea Acknowledgements: This research was supported by the Agency for Defense Development (UD14003DD) and by "Marine geological and geophysical mapping of the Korean seas" of the Korea Institute of Geoscience and Mineral Resources (KIGAM).

  5. On the intergalactic temperature-density relation

    Science.gov (United States)

    McQuinn, Matthew; Upton Sanderbeck, Phoebe R.

    2016-02-01

    Cosmological simulations of the low-density intergalactic medium exhibit a strikingly tight power-law relation between temperature and density that holds over two decades in density. It is found that this relation should roughly apply Δz ˜ 1-2 after a reionization event, and this limiting behaviour has motivated the power-law parameterizations used in most analyses of the Ly α forest. This relation has been explained by using equations linearized in the baryonic overdensity (which does not address why a tight power-law relation holds over two decades in density) or by equating the photoheating rate with the cooling rate from cosmological expansion (which we show is incorrect). Previous explanations also did not address why recombination cooling and Compton cooling off of the cosmic microwave background, which are never negligible, do not alter the character of this relation. We provide an understanding for why a tight power-law relation arises for unshocked gas at all densities for which collisional cooling is unimportant. We also use our results to comment on (1) how quickly fluctuations in temperature redshift away after reionization processes, (2) how much shock heating occurs in the low-density intergalactic medium, and (3) how the temperatures of collapsing gas parcels evolve.

  6. Prediction of Minimum Spouting Velocity at Elevated Pressures and Temperatures

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Minimum spouting velocity (Ums) is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology was initiated in 1955. In this paper, a new correlation is developed for Ums based on 767 published experimental data covering both high pressure and high temperature conditions. The calculated and the measured results of Ums are in better agreement than other published correlations.

  7. Dependence of friction on roughness, velocity, and temperature.

    Science.gov (United States)

    Sang, Yi; Dubé, Martin; Grant, Martin

    2008-03-01

    We study the dependence of friction on surface roughness, sliding velocity, and temperature. Expanding on the classic treatment of Greenwood and Williamson, we show that the fractal nature of a surface has little influence on the real area of contact and the static friction coefficient. A simple scaling argument shows that the static friction exhibits a weak anomaly mu ~ A(0)(-chi/4), where A0 is the apparent area and chi is the roughness exponent of the surface. We then develop a method to calculate atomic-scale friction between a microscopic asperity, such as the tip of a friction force microscope (FFM) and a solid substrate. This method, based on the thermal activation of the FFM tip, allows a quantitative extraction of all the relevant microscopic parameters and reveals a universal scaling behavior of atomic friction on velocity and temperature. This method is extended to include a soft atomic substrate in order to simulate FFM scans more realistically. The tip is connected with the support of the cantilever by an ideal spring and the substrate is simulated with a ball-spring model. The tip and substrate are coupled with repulsive potentials. Simulations are done at different temperatures and scanning velocities on substrates with different elastic moduli. Stick-slip motion of the tip is observed, and the numerical results of the friction force and distribution of force maxima match the theoretical framework.

  8. Fluorescence-Doped Particles for Simultaneous Temperature and Velocity Imaging

    Science.gov (United States)

    Danehy, Paul M.; Tiemsin, Pacita I.; Wohl, Chrostopher J.; Verkamp, Max; Lowe, T.; Maisto, P.; Byun, G.; Simpson, R.

    2012-01-01

    Polystyrene latex microspheres (PSLs) have been used for particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements for several decades. With advances in laser technologies, instrumentation, and data processing, the capability to collect more information about fluid flow beyond velocity is possible using new seed materials. To provide additional measurement capability, PSLs were synthesized with temperature-sensitive fluorescent dyes incorporated within the particle. These multifunctional PSLs would have the greatest impact if they could be used in large scale facilities with minimal modification to the facilities or the existing instrumentation. Consequently, several potential dyes were identified that were amenable to existing laser systems currently utilized in wind tunnels at NASA Langley Research Center as well as other wind and fluid (water) tunnels. PSLs incorporated with Rhodamine B, dichlorofluorescein (DCF, also known as fluorescein 548 or fluorescein 27) and other dyes were synthesized and characterized for morphology and spectral properties. The resulting particles were demonstrated to exhibit fluorescent emission, which would enable determination of both fluid velocity and temperature. They also would allow near-wall velocity measurements whereas laser scatter from surfaces currently prevents near-wall measurements using undoped seed materials. Preliminary results in a wind tunnel facility located at Virginia Polytechnic Institute and State University (Virginia Tech) have verified fluorescent signal detection and temperature sensitivity of fluorophore-doped PSLs.

  9. Composition versus temperature induced velocity heterogeneities in a pyrolitic lower mantle

    Science.gov (United States)

    Wu, Zhongqing; Wentzcovitch, Renata M.

    2017-01-01

    Interpretation of lateral velocity heterogeneities is essential for our understanding of Earth's interior. Ferropericlase's (Fp) spin crossover (FSC) fundamentally changes their interpretation in the mid lower mantle. In a typical pyrolitic aggregate, FSC induces an unusual increase in bulk sound velocity (Vϕ) with increasing temperature at mid-lower-mantle depths. This reduces the sensitivity of longitudinal velocity (VP) to lateral temperature variations around 1700 km. Here we show that FSC also dramatically impacts the manifestation of two important types of compositional heterogeneities: i) variations in iron concentration in Fp, e.g., caused by changes in iron partitioning; ii) variation in molar fraction of Fp, as expected in slab subduction regions. FSC enhances the sensitivity of Vϕ and VP to these compositional variations by several-fold at similar depths. The opposite effects of lateral variations of temperature and composition on VP is critical for distinguishing the possible physical origin of heterogeneities in tomographic P-models. Temperature and composition variations also produce opposite types of correlation between Vϕ and shear velocity (VS) heterogeneities and between VS and density (ρ) heterogeneities. Only lateral temperature variations can produce anti-correlation between Vϕ and VS at mid lower mantle depths, while only these compositional variations can produce anti-correlation between VS and ρ in the spin crossover region and at greater depths. Together these effects suggest that heterogeneities in VP in the mid lower mantle common to multiple seismic models could originate in simultaneous lateral temperature and compositional variations in this region.

  10. Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

    Science.gov (United States)

    Olsen, Jeppe; Madsen, Jens; Nielsen, Anders Henry; Rasmussen, Jens Juul; Naulin, Volker

    2016-04-01

    The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocity scaling, which is proportional to the ion acoustic speed times the square root of the filament particle density times the sum of the electron and ion temperature perturbations. Only for small blobs the cross field convection does not follow this scaling. The influence of finite Larmor radius effects on the cross-field blob convection is shown not to depend strongly on the dynamical ion temperature field. The blob dynamics of constant finite and dynamical ion temperature blobs is similar. When the blob size is on the order of 10 times the ion Larmor radius the blobs stay coherent and decelerate slowly compared to larger blobs which dissipate faster due to fragmentation and turbulent mixing.

  11. Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, T.; Meyer, L. [Forschungszentrum Karlsruhe (Germany)

    1995-09-01

    Turbulent air flow in a wall sub-channel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. measurements were performed with hot-wire probe with X-wires and a temperature wire. The mean velocity, the mean fluid temperature, the wall shear stress and wall temperature, the turbulent quantities such as the turbulent kinetic energy, the Reynolds-stresses and the turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large scale periodic fluctuations are responsible for the high intersubchannel heat and momentum exchange.

  12. Variable temperature hot wire anemometry applied to the joint analysis of the velocity and temperature fluctuations in a mixing layer

    OpenAIRE

    Ndoye, M.; Delville, J.; Dorignac, E.; Arroyo, G.

    2011-01-01

    International audience; Our study provides a detailed description of the thermal mixing process in an anisothermal mixing layer. Velocity and temperature are simultaneously measured at the same point by using a new hot wire anemometer. This anemometer implements the multiple overheat principle, associated with a non linear Levenberg-Marquardt signal processing. These simultaneous measurements allowed an analysis based on conditional Probability Density Functions (PDFs), joint PDFs and a quadr...

  13. Effects of beam velocity and density on an ion-beam pulse moving in magnetized plasmas

    CERN Document Server

    Zhao, Xiao-ying; Zhao, Yong-tao; Qi, Xin; Yang, Lei

    2016-01-01

    The wakefield and stopping power of an ion-beam pulse moving in magnetized plasmas are investigated by particle-in-cell (PIC) simulations. The effects of beam velocity and density on the wake and stopping power are discussed. In the presence of magnetic field, it is found that beside the longitudinal conversed V-shaped wakes, the strong whistler wave are observed when low-density and low-velocity pulses moving in plasmas. The corresponding stopping powers are enhanced due to the drag of these whistler waves. As beam velocities increase, the whistler waves disappear, and only are conversed V-shape wakes observed. The corresponding stopping powers are reduced compared with these in isotropic plasmas. When high-density pulses transport in the magnetized plasmas, the whistler waves are greatly inhibited for low-velocity pulses and disappear for high-velocity pulses. Additionally, the magnetic field reduces the stopping powers for all high-density cases.

  14. Experimental study of the velocity of density currents in convergent and divergent channels

    Institute of Scientific and Technical Information of China (English)

    Hasan Torabi POUDEH; Samad EMAMGHOLIZADEH; Manoocher Fathi-MOGHADAM

    2014-01-01

    The head velocity of the density current in the convergent and divergent channel is a key parameter for evaluating the extent to which suspended material travels, and for determining the type and distribution of sediment in the water body. This study experimentally evaluated the effects of the reach degree of convergence and divergence on the head velocity of the density current. Experiments were conducted in the flume with 6.0 m long, 0.72 m width and 0.6 m height. The head velocity was measured at three convergent degrees (-8o;-12o;-26o), at three divergent degrees (8o; 12o; 26o) and two slopes (0.009, 0.016) for various discharges. The measured head velocity of the density current is compared with the head velocity of the density current in the constant cross section channel. Based on non-dimensional and statistical analysis, relations as linear multiple regression are offered for predicting head velocity of the density current in the convergent, divergent and constant cross section channel. Also the results of this research show that for the same slope and discharge, the head velocity of the density current in the convergent and divergent channel are greater and less than the head velocity of the constant cross section, respectively.

  15. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    Science.gov (United States)

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations.

  16. Numerical calculation of air velocity and temperature in ice rinks

    Energy Technology Data Exchange (ETDEWEB)

    Bellache, O.; Galanis, N. [Sherbrooke Univ., PQ (Canada); Ouzzane, M.; Sunye, R. [Natural Resources Canada, Varennes, PQ (Canada). CANMET Energy Diversification Laboratory

    2002-07-01

    A computational fluid dynamic (CFD) model was developed to predict the energy consumption at an ice rink. Ice rinks in Canada consume approximately 3500 GWh of electricity annually and generate about 300,000 tons of gases contributing to the greenhouse effect. This newly developed model also considers ice quality and comfort conditions in the arena. The typical 2D configuration includes refrigeration loads as well as heat transfer coefficients between the air and the ice. The effects of heat losses through the ice rink envelope are also determined. A comparison of prediction results from 4 different formulations confirms that there are important differences in air velocities near the walls and in the temperature gradient near the ice. The turbulent mixed convection model gives the best estimate of the refrigeration load. It was determined that a good ventilation should circulate air throughout the building to avoid stagnant areas. Air velocities must be low near the stands where the temperature should be around 20 degrees C. Air temperature near the ice should be low to preserve ice quality and to reduce the refrigeration load. The complexity of this geometry has been taken into account in a numerical simulation of the hydrodynamic and thermal fields in the ice rink. 9 refs., 2 tabs., 5 figs.

  17. A probability density function of liftoff velocities in mixed-size wind sand flux

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With the discrete element method(DEM) ,employing the diameter distribution of natural sands sampled from the Tengger Desert,a mixed-size sand bed was produced and the particle-bed collision was simulated in the mixed-size wind sand movement. In the simulation,the shear wind velocity,particle diameter,incident velocity and incident angle of the impact sand particle were given the same values as the experimental results. After the particle-bed collision,we collected all the initial velocities of rising sand particles,including the liftoff angular velocities,liftoff linear velocities and their horizontal and vertical components. By the statistical analysis on the velocity sample for each velocity component,its probability density functions were obtained,and they are the functions of the shear wind velocity. The liftoff velocities and their horizontal and vertical components are distributed as an exponential density function,while the angular velocities are distributed as a normal density function.

  18. On the intergalactic temperature-density relation

    CERN Document Server

    McQuinn, Matthew

    2015-01-01

    Cosmological simulations of the low-density intergalactic medium exhibit a strikingly tight power-law relation between temperature and density that holds over two decades in density. It is found that this relation should roughly apply Delta z ~ 1-2 after a reionization event, and this limiting behavior has motivated the power-law parameterizations used in most analyses of the Ly-alpha forest. This relation has been explained by using equations linearized in the baryonic overdensity (which does not address why a tight power-law relation holds over two decades in density) or by equating the photoheating rate with the cooling rate from cosmological expansion (which we show is incorrect). Previous explanations also did not address why recombination cooling and Compton cooling off of the cosmic microwave background, which are never negligible, do not alter the character of this relation. We provide an understanding for why a tight power-law relation arises for unshocked gas at all densities for which collisional c...

  19. Small velocity and finite temperature variations in kinetic relaxation models

    KAUST Repository

    Markowich, Peter

    2010-01-01

    A small Knuden number analysis of a kinetic equation in the diffusive scaling is performed. The collision kernel is of BGK type with a general local Gibbs state. Assuming that the flow velocity is of the order of the Knudsen number, a Hilbert expansion yields a macroscopic model with finite temperature variations, whose complexity lies in between the hydrodynamic and the energy-transport equations. Its mathematical structure is explored and macroscopic models for specific examples of the global Gibbs state are presented. © American Institute of Mathematical Sciences.

  20. Dynamical density fluctuations of superfluids near the critical velocity.

    Science.gov (United States)

    Kato, Yusuke; Watabe, Shohei

    2010-07-16

    We propose a stability criterion of superfluids in condensed Bose-Einstein systems, which incorporates the spectral function or the autocorrelation function of the local density. Within the Gross-Pitaevskii-Bogoliubov theory, we demonstrate the validity of our criterion for the soliton-emission instability, with use of explicit forms of zero modes of the Bogoliubov equation and a dynamical scaling near the saddle-node bifurcation. We also show that the criterion is applicable to the Landau phonon instability and the Landau roton instability within the single-mode approximation.

  1. Waves in cell monolayer without proliferation: density determines cell velocity and wave celerity

    CERN Document Server

    Tlili, S; Li, B; Cardoso, O; Ladoux, B; Delanoë-Ayari, H; Graner, F

    2016-01-01

    Collective cell migration contributes to morphogenesis, wound healing or tumor metastasis. Culturing epithelial monolayers on a substrate is an in vitro configuration suitable to quantitatively characterize such tissue migration by measuring cell velocity, density and cell-substrate interaction force. Inhibiting cell division, we limit cell density increase and favor steady cell migration, while by using long narrow strips we stabilise the migrating front shape, so that we observe migration over a day or more. In the monolayer bulk, the cell velocity is a function of the cell density, namely it increases as a linear function of the cell radius. At least ten periods of propagating velocity waves are detected with a high signal-to-noise ratio, enabling for their quantitative spatio-temporal analysis. Cell density displays waves, in phase opposition with the velocity, as predicted by mass conservation; similarly, cell-substrate force appear to display small amplitude waves, in phase quadrature with respect to ve...

  2. Shock wave velocity and shock pressure for low density powders : A novel approach

    NARCIS (Netherlands)

    Dijken, D.K.; Hosson, J.Th.M. De

    1994-01-01

    A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new mod

  3. SHOCK-WAVE VELOCITY AND SHOCK PRESSURE FOR LOW-DENSITY POWDERS - A NOVEL-APPROACH

    NARCIS (Netherlands)

    DIJKEN, DK; DEHOSSON, JTM

    1994-01-01

    A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new mod

  4. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    OpenAIRE

    Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

    2016-01-01

    We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry out $\\sim 4.6$pc resolution $N$-body+adaptive mesh refinement (AMR) hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way (MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed ...

  5. Density, Velocity and Ionization Structure in Accretion-Disc Winds

    Science.gov (United States)

    Sonneborn, George (Technical Monitor); Long, Knox

    2004-01-01

    This was a project to exploit the unique capabilities of FUSE to monitor variations in the wind- formed spectral lines of the luminous, low-inclination, cataclysmic variables(CV) -- RW Sex. (The original proposal contained two additional objects but these were not approved.) These observations were intended to allow us to determine the relative roles of density and ionization state changes in the outflow and to search for spectroscopic signatures of stochastic small-scale structure and shocked gas. By monitoring the temporal behavior of blue-ward extended absorption lines with a wide range of ionization potentials and excitation energies, we proposed to track the changing physical conditions in the outflow. We planned to use a new Monte Carlo code to calculate the ionization structure of and radiative transfer through the CV wind. The analysis therefore was intended to establish the wind geometry, kinematics and ionization state, both in a time-averaged sense and as a function of time.

  6. Sound velocities of bridgmanite from density of states determined by nuclear inelastic scattering and first-principles calculations

    Science.gov (United States)

    McCammon, Catherine; Caracas, Razvan; Glazyrin, Konstantin; Potapkin, Vasily; Kantor, Anastasia; Sinmyo, Ryosuke; Prescher, Clemens; Kupenko, Ilya; Chumakov, Aleksandr; Dubrovinsky, Leonid

    2016-12-01

    Sound velocities of bridgmanite measured in the laboratory are a key to deciphering the composition of the lower mantle. Here, we report Debye sound velocities determined using nuclear inelastic scattering (NIS) for one majorite composition (Mg0.82Fe0.18SiO3) and five bridgmanite compositions (Mg0.82Fe0.18SiO3, Mg0.86Fe0.14Si0.98Al0.02O3, Mg0.88Fe0.12SiO3, Mg0.6Fe0.4Si0.63Al0.37O3, Mg0.83Fe0.15Si0.98Al0.04O3) measured in a diamond anvil cell at pressures up to 89 GPa at room temperature. Debye sound velocities for majorite determined from NIS are consistent with literature data from Brillouin scattering and ultrasonics, while Debye sound velocities for bridgmanite are significantly lower than literature values from the same methods. We calculated partial and total density of states (DOS) for MgSiO3 and FeSiO3 bridgmanite using density functional theory and demonstrate that Debye sound velocities calculated from the reduced DOS using the same approach as for the experimental data (i.e., the limit of D(E)/E2 as energy goes to zero) give the same sound velocities for each phase irrespective of which partial DOS is used. In addition, we show that Debye sound velocities calculated using this approach are consistent with values obtained from the calculation of the full elastic tensor. Comparison of the calculated DOS with the one obtained from NIS indicates that the experimental DOS has enhanced intensity at low energies that leads to a different slope of the DOS and hence a lower sound velocity. This effect is present in all of the bridgmanite samples examined in this study.

  7. Effects of density, velocity gradient, and compressibility on side-jet formation in round jets with variable density

    Science.gov (United States)

    Muramatsu, Akinori

    2013-11-01

    When a low density gas compared with the ambient gas is discharged from a round nozzle, side jets that are radial ejections of jet fluid are generated at the initial region of the jet. The density ratio between the jet fluid and the ambient fluid is a main parameter for the side-jet formation. Since the side-jet formation is also related to the instability of shear layer, it depends on the velocity gradient of the shear layer in the jet. The velocity gradient is evaluated by a ratio of the momentum thickness and the nozzle diameter at the nozzle exit. Compressibility suppresses the instability and the generation of the side jets. The compressibility is evaluated by a Mach number, which is a ratio defined by an issuing velocity of the jet and a sound velocity in the ambient fluid. Influence of these three parameters on the side-jet formation was examined experimentally. The density ratio and momentum thickness ratio were varied from 0.14 to 1.53, and from 14 to 155, respectively. The Mach number was varied to 0.7. Existence of side jets was confirmed by flow visualization using a laser sheet. Domains for the side-jet formation by the density ratio, the momentum thickness ratio, and the Mach number were determined.

  8. Gas density fluctuations in the Perseus Cluster: clumping factor and velocity power spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravleva, I.; Churazov, E.; Arevalo, P.; Schekochihin, A. A.; Allen, S. W.; Fabian, A. C.; Forman, W. R.; Sanders, J. S.; Simionescu, A.; Sunyaev, R.; Vikhlinin, A.; Werner, N.

    2015-05-20

    X-ray surface brightness fluctuations in the core of the Perseus Cluster are analysed, using deep observations with the Chandra observatory. The amplitude of gas density fluctuations on different scales is measured in a set of radial annuli. It varies from 7 to 12 per cent on scales of ~10–30 kpc within radii of 30–220 kpc from the cluster centre. Using a statistical linear relation between the observed amplitude of density fluctuations and predicted velocity, the characteristic velocity of gas motions on each scale is calculated. The typical amplitudes of the velocity outside the central 30 kpc region are 90–140 km s-1 on ~20–30 kpc scales and 70–100 km s-1 on smaller scales ~7–10 kpc. The velocity power spectrum (PS) is consistent with cascade of turbulence and its slope is in a broad agreement with the slope for canonical Kolmogorov turbulence. The gas clumping factor estimated from the PS of the density fluctuations is lower than 7–8 per cent for radii ~30–220 kpc from the centre, leading to a density bias of less than 3–4 per cent in the cluster core. Uncertainties of the analysis are examined and discussed. Future measurements of the gas velocities with the Astro-H, Athena and Smart-X observatories will directly measure the gas density–velocity perturbation relation and further reduce systematic uncertainties in this analysis.

  9. Temperature and Density Structure of a Recurring Active Region Jet

    CERN Document Server

    Mulay, Sargam M; Mason, Helen

    2016-01-01

    We present a study of a recurring jet observed on October 31, 2011 by SDO/AIA, Hinode/XRT and Hinode/EIS. We discuss the physical parameters of the jet such as density, differential emission measure, peak temperature, velocity and filling factor obtained using imaging and spectroscopic observations. A differential emission measure (DEM) analysis was performed at the region of the jet-spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The plasma along the line-of-sight in the jet-spire and jet-footpoint was found to be peak at 2.0 MK. We calculated electron densities using the Fe XII ($\\lambda$186/$\\lambda$195) line ratio in the region of the spire (Ne = 7.6x$10^{10}$ $cm^{-3}$) and the footpoint (1.1x$10^{11}$ $cm^{-3}$). The plane-of-sky velocity of the jet is found to be 524 km/s. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. There is no in...

  10. Correlation of densities with shear wave velocities and SPT N values

    Science.gov (United States)

    Anbazhagan, P.; Uday, Anjali; Moustafa, Sayed S. R.; Al-Arifi, Nassir S. N.

    2016-06-01

    Site effects primarily depend on the shear modulus of subsurface layers, and this is generally estimated from the measured shear wave velocity (V s) and assumed density. Very rarely, densities are measured for amplification estimation because drilling and sampling processes are time consuming and expensive. In this study, an attempt has been made to derive the correlation between the density (dry and wet density) and V s/SPT (standard penetration test) N values using measured data. A total of 354 measured V s and density data sets and 364 SPT N value and density data sets from 23 boreholes have been used in the study. Separate relations have been developed for all soil types as well as fine-grained and coarse-grained soil types. The correlations developed for bulk density were compared with the available data and it was found that the proposed relation matched well with the existing data. A graphical comparison and validation based on the consistency ratio and cumulative frequency curves was performed and the newly developed relations were found to demonstrate good prediction performance. An attempt has also been made to propose a relation between the bulk density and shear wave velocity applicable for a wide range of soil and rock by considering data from this study as well as that of previous studies. These correlations will be useful for predicting the density (bulk and dry) of sites having measured the shear wave velocity and SPT N values.

  11. Asymmetric Velocity Distributions from Halo Density Profiles in the Eddington Approach

    Directory of Open Access Journals (Sweden)

    J. D. Vergados

    2015-01-01

    Full Text Available We show how to obtain the energy distribution f(E in our vicinity starting from WIMP density profiles in a self-consistent way by employing the Eddington approach and adding reasonable angular momentum dependent terms in the expression of the energy. We then show how we can obtain the velocity dispersions and the asymmetry parameter β in terms of the parameters describing the angular momentum dependence. From this expression, for f(E, we proceed to construct an axially symmetric WIMP a velocity distribution, which, for a gravitationally bound system, automatically has a velocity upper bound and is characterized by the same asymmetriy β. This approach is tested and clarified by constructing analytic expressions in a simple model, with adequate structure. We then show how such velocity distributions can be used in determining the event rates, including modulation, in both the standard and the directional WIMP searches.

  12. Correlation of seismic wave velocities with fracture densities: Implications for the critical zone in mountain watersheds

    Science.gov (United States)

    Peters, M. P.; Holbrook, W. S.; Flinchum, B. A.; Pasquet, S.

    2016-12-01

    Despite increasing scientific interest in the critical zone, the accurate determination of fracture density in the subsurface remains difficult as access and costs can prohibit ground-truthing through drilling. A more precise characterization of the fracturing process provides critical insight in to subsurface structures. This is particularly important in determining the point at which protolithic rock becomes fractured bedrock and then degrades to soil through the process of weathering. We studied outcrops in the Laramie Range of southeastern Wyoming were studied and fracture densities were correlated with seismic pressure (P) wave velocities. We used the Differential Effective Medium (DEM) rock physics model to validate our findings and provide a more robust characterization of the role of P-wave velocities acquired on outcrops play in critical zone science. This approach marks a significant departure from previous research, which has not applied P-wave fracture relationships in outcrops onto the critical zone for subsurface characterization. We compared our results with borehole data to establish a relationship between surface outcrops and subsurface rock structures. We found a clear, inverse relationship between a decrease in P-wave velocity and an increase in fracture density consistent with borehole data in the studied area. Our findings suggest that outcrops can be used to determine fracture density in the critical zone. We show that the use of seismic refraction surveys on outcrops provides a non-invasive, highly transferrable method through which we can predict fracturing densities in the subsurface.

  13. Collective Thomson scattering for ion temperature and velocity measurements on Magnum-PSI: a feasibility study

    Science.gov (United States)

    van der Meiden, H. J.

    2010-04-01

    In this paper, collective Thomson scattering (CTS) is proposed for measuring the ion temperature and axial/rotational velocity of a plasma jet in the linear plasma generator Magnum-PSI, where ITER-relevant plasma conditions will be simulated. CTS is feasible at Magnum-PSI, because high electron densities (ne) can be obtained at low electron temperatures, which means that small Debye lengths are achievable. Calculations show that CTS is possible at the fundamental wavelength (1064 nm) of a Nd : YAG laser. At this wavelength, a scattering angle of 17-35° is sufficiently small to achieve a scattering parameter 1 1.5 × 1021 m-3. The design considerations of the CTS diagnostic are described in this paper.

  14. Effective temperatures, rotational velocities, microturbulent velocities and abundances in the atmospheres of the Sun,. HD1835 and HD10700

    CERN Document Server

    Pavlenko, Ya V; Jones, H R A; Ivanyuk, O; Pinfield, D J

    2012-01-01

    We describe our procedure to determine effective temperatures, rotational velocities, microturbulent velocities, and chemical abundances in the atmospheres of Sun-like stars. We use independent determinations of iron abundances using the fits to the observed Fe I and Fe II atomic absorption lines. We choose the best solution from the fits to these spectral features for the model atmosphere that provides the best confidence in the determined log N(Fe), Vt, and vsini. First, we compute the abundance of iron for a set of adopted microturbulent velocities. To determine the most self-consistent effective temperature and microturbulent velocity in any star's atmosphere, we used an additional constraint where we minimise the dependence of the derived abundances of Fe I and Fe II on the excitation potential of the corresponding lines. We analyse the spectra of the Sun and two well known solar type stars, HD1835 and HD10700 to determine their abundances, microturbulent velocity and rotational velocity. For the Sun abu...

  15. Gas Density Fluctuations in the Perseus Cluster: Clumping Factor and Velocity Power Spectrum

    CERN Document Server

    Zhuravleva, I; Arevalo, P; Schekochihin, A A; Allen, S W; Fabian, A C; Forman, W R; Sanders, J S; Simionescu, A; Sunyaev, R; Vikhlinin, A; Werner, N

    2015-01-01

    X-ray surface brightness fluctuations in the core of the Perseus Cluster are analyzed, using deep observations with the Chandra observatory. The amplitude of gas density fluctuations on different scales is measured in a set of radial annuli. It varies from 8 to 12 per cent on scales of ~10-30 kpc within radii of 30-160 kpc from the cluster center and from 9 to 7 per cent on scales of ~20-30 kpc in an outer, 60-220 kpc annulus. Using a statistical linear relation between the observed amplitude of density fluctuations and predicted velocity, the characteristic velocity of gas motions on each scale is calculated. The typical amplitudes of the velocity outside the central 30 kpc region are 90-140 km/s on ~20-30 kpc scales and 70-100 km/s on smaller scales ~7-10 kpc. The velocity power spectrum is consistent with cascade of turbulence and its slope is in a broad agreement with the slope for canonical Kolmogorov turbulence. The gas clumping factor estimated from the power spectrum of the density fluctuations is low...

  16. Elastic and piezoelectric properties, sound velocity and Debye temperature of (B3) boron–bismuth compound under pressure

    Indian Academy of Sciences (India)

    S Daoud; N Bioud; N Lebgaa

    2013-11-01

    Pseudopotential plane-wave method (PP–PW) based on density functional theory (DFT) and density functional perturbation theory (DFPT) within the Teter and Pade exchangecorrelation functional form of the local spin density approximation (LSDA) is applied to study the effect of pressure on the elastic and piezoelectric properties of the (B3) boron–bismuth compound. The phase transition, the independent elastic stiffness constants, the bulk modulus, the direct and converse piezoelectric coefficients, the longitudinal, transverse, and average sound velocities, and finally the Debye temperature under pressure are studied. The results obtained are generally lower than the available theoretical data (experimental data are not available) reported in the literature.

  17. Near Continuum Velocity and Temperature Coupled Compressible Boundary Layer Flow over a Flat Plate

    Science.gov (United States)

    He, Xin; Cai, Chunpei

    2017-04-01

    The problem of a compressible gas flows over a flat plate with the velocity-slip and temperature-jump boundary conditions are being studied. The standard single- shooting method is applied to obtain the exact solutions for velocity and temperature profiles when the momentum and energy equations are weakly coupled. A double-shooting method is applied if these two equations are closely coupled. If the temperature affects the velocity directly, more significant velocity slip happens at locations closer to the plate's leading edge, and inflections on the velocity profiles appear, indicating flows may become unstable. As a consequence, the temperature-jump and velocity-slip boundary conditions may trigger earlier flow transitions from a laminar to a turbulent flow state.

  18. Joint probability density function modeling of velocity and scalar in turbulence with unstructured grids

    CERN Document Server

    Bakosi, J; Boybeyi, Z

    2010-01-01

    In probability density function (PDF) methods a transport equation is solved numerically to compute the time and space dependent probability distribution of several flow variables in a turbulent flow. The joint PDF of the velocity components contains information on all one-point one-time statistics of the turbulent velocity field, including the mean, the Reynolds stresses and higher-order statistics. We developed a series of numerical algorithms to model the joint PDF of turbulent velocity, frequency and scalar compositions for high-Reynolds-number incompressible flows in complex geometries using unstructured grids. Advection, viscous diffusion and chemical reaction appear in closed form in the PDF formulation, thus require no closure hypotheses. The generalized Langevin model (GLM) is combined with an elliptic relaxation technique to represent the non-local effect of walls on the pressure redistribution and anisotropic dissipation of turbulent kinetic energy. The governing system of equations is solved fully...

  19. Characteristics of wind velocity and temperature change near an escarpment-shaped road embankment.

    Science.gov (United States)

    Kim, Young-Moon; You, Ki-Pyo; You, Jang-Youl

    2014-01-01

    Artificial structures such as embankments built during the construction of highways influence the surrounding airflow. Various types of damage can occur due to changes in the wind velocity and temperature around highway embankments. However, no study has accurately measured micrometeorological changes (wind velocity and temperature) due to embankments. This study conducted a wind tunnel test and field measurement to identify changes in wind velocity and temperature before and after the construction of embankments around roads. Changes in wind velocity around an embankment after its construction were found to be influenced by the surrounding wind velocity, wind angle, and the level difference and distance from the embankment. When the level difference from the embankment was large and the distance was up to 3H, the degree of wind velocity declines was found to be large. In changes in reference wind velocities around the embankment, wind velocity increases were not proportional to the rate at which wind velocities declined. The construction of the embankment influenced surrounding temperatures. The degree of temperature change was large in locations with large level differences from the embankment at daybreak and during evening hours when wind velocity changes were small.

  20. Characteristics of Wind Velocity and Temperature Change Near an Escarpment-Shaped Road Embankment

    Directory of Open Access Journals (Sweden)

    Young-Moon Kim

    2014-01-01

    Full Text Available Artificial structures such as embankments built during the construction of highways influence the surrounding airflow. Various types of damage can occur due to changes in the wind velocity and temperature around highway embankments. However, no study has accurately measured micrometeorological changes (wind velocity and temperature due to embankments. This study conducted a wind tunnel test and field measurement to identify changes in wind velocity and temperature before and after the construction of embankments around roads. Changes in wind velocity around an embankment after its construction were found to be influenced by the surrounding wind velocity, wind angle, and the level difference and distance from the embankment. When the level difference from the embankment was large and the distance was up to 3H, the degree of wind velocity declines was found to be large. In changes in reference wind velocities around the embankment, wind velocity increases were not proportional to the rate at which wind velocities declined. The construction of the embankment influenced surrounding temperatures. The degree of temperature change was large in locations with large level differences from the embankment at daybreak and during evening hours when wind velocity changes were small.

  1. Evolution of density and velocity profiles of dark matter and dark energy in spherical voids

    CERN Document Server

    Novosyadlyj, Bohdan; Kulinich, Yurij

    2016-01-01

    We analyse the evolution of cosmological perturbations which leads to the formation of large isolated voids in the Universe. We assume that initial perturbations are spherical and all components of the Universe (radiation, matter and dark energy) are continuous media with perfect fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations for every component in the comoving to cosmological background reference frame are obtained from equations of energy and momentum conservation and Einstein's ones and are integrated numerically. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is much larger than the particle horizon. Results show how the profiles of density and velocity of matter and dark energy are formed and how they depend on parameters of dark energy and initial conditions. In particular, it is shown that final matter density and velocity amplitudes change within range $\\sim$4-7...

  2. Non-zero density-velocity consistency relations for large scale structures

    CERN Document Server

    Rizzo, Luca Alberto; Valageas, Patrick

    2016-01-01

    We present exact kinematic consistency relations for cosmological structures that do not vanish at equal times and can thus be measured in surveys. These rely on cross-correlations between the density and velocity, or momentum, fields. Indeed, the uniform transport of small-scale structures by long wavelength modes, which cannot be detected at equal times by looking at density correlations only, gives rise to a shift in the amplitude of the velocity field that could be measured. These consistency relations only rely on the weak equivalence principle and Gaussian initial conditions. They remain valid in the non-linear regime and for biased galaxy fields. They can be used to constrain non-standard cosmological scenarios or the large-scale galaxy bias.

  3. Power spectral density of velocity fluctuations estimated from phase Doppler data

    Directory of Open Access Journals (Sweden)

    Jicha Miroslav

    2012-04-01

    Full Text Available Laser Doppler Anemometry (LDA and its modifications such as PhaseDoppler Particle Anemometry (P/DPA is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain – calculation of power spectral density (PSD of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused by seeding density and other factors of the flow and LDA setup. Arbitrary results of LDA measurements are compared with corresponding Hot Wire Anemometry (HWA data in the frequency domain. Slot correlation (SC method implemented in software program Kern by Nobach (2006 is used for the PSD estimation. Influence of several input parameters on resulting PSDs is described. Optimum setup of the software for our data of particle-laden air flow in realistic human airway model is documented. Typical character of the flow is described using PSD plots of velocity fluctuations with comments on specific properties of the flow. Some recommendations for improvements of future experiments to acquire better PSD results are given.

  4. On density and velocity fields and $\\beta$ from the IRAS PSCz survey

    CERN Document Server

    Schmoldt, I M; Saha, P; Branchini, E; Efstathiou, G P; Frenk, C S; Keeble, O; Maddox, S J; McMahon, R; Oliver, S; Rowan-Robinson, M; Saunders, W J; Sutherland, W J; Tadros, H; White, S D M; Schmoldt, Inga M.; Saar, Veikko; Saha, Prasenjit

    1999-01-01

    We present a version of the Fourier Bessel method first introduced by Fisher et al (1994) and Zaroubi et al (1994) with two extensions: (a) we amend the formalism to allow a generic galaxy weight which can be constant rather than the more conventional overweighting of galaxies at high distances, and (b) we correct for the masked zones by extrapolation of Fourier Bessel modes rather than by cloning from the galaxy distribution in neighbouring regions. We test the procedure extensively on N-body simulations and find that it gives generally unbiased results but that the reconstructed velocities tend to be overpredicted in high-density regions. Applying the formalism to the PSZz redshift catalog, we find that beta = 0.7 +/- 0.5 from a comparison of the reconstructed Local Group velocity to the CMB dipole. From an anisotropy test of the velocity field, we find that beta = 1 CDM models models normalized to the current cluster abundance can be excluded with 90% confidence. The density and velocity fields reconstruct...

  5. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    Science.gov (United States)

    Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

    2017-04-01

    We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (H I) in disc galaxies. For our analysis, we carry out ∼4.6 pc resolution N-body+adaptive mesh refinement hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way and a Large and Small Magellanic Cloud. We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed H I in local spiral galaxies from THINGS (The H I Nearby Galaxy Survey). Our models with stellar feedback give an excellent match to the observed THINGS H I density power spectra. We find that kinetic energy power spectra in feedback-regulated galaxies, regardless of galaxy mass and size, show scalings in excellent agreement with supersonic turbulence (E(k) ∝ k-2) on scales below the thickness of the H I layer. We show that feedback influences the gas density field, and drives gas turbulence, up to large (kpc) scales. This is in stark contrast to density fields generated by large-scale gravity-only driven turbulence. We conclude that the neutral gas content of galaxies carries signatures of stellar feedback on all scales.

  6. Hole boring velocity measurements in near critical density plasmas by a CO2 laser pulse

    Science.gov (United States)

    Gong, Chao; Tochitsky, Sergei; Pigeon, Jeremy; Joshi, Chan

    2014-10-01

    Measurements of plasma dynamics during the interaction of a high-power laser pulse with an above critical density plasma is important for understanding absorption, transport and particle acceleration mechanisms. An important process that affects these mechanisms is hole boring occurring at the critical density because of the radiation pressure of the laser pulse. Yet, no systematic measurements of the hole boring velocity's (vhb) dependence on laser intensity (I) have been made. In this talk, we present experimental results of vhb in near critical density plasmas produced by CO2 laser as a function of I in the range of 1*1015 to 1.6*1016 W/cm2. A novel four frame Mach-Zehnder interferometer using a 1 ps, 532 nm probe laser pulse was developed to record the evolution of the plasma density profile and the motion of the near critical density layer. Using this diagnostic, we observed the motion of the steepened plasma profile due to the incident, time-structured CO2 laser pulse. Experimental results show the hole boring velocity increases from 0.004c to 0.007c as the laser intensity is increased from 1*1015 to 1.6*1016 W/cm2. This work is supported by DOE grant DE-FG02-92-ER40727, NSF grant PHY-0936266 at UCLA.

  7. The Surface Density Profile of the Galactic Disk from the Terminal Velocity Curve

    CERN Document Server

    McGaugh, Stacy S

    2015-01-01

    The mass distribution of the Galactic disk is constructed from the terminal velocity curve and the mass discrepancy-acceleration relation. Mass models numerically quantifying the detailed surface density profiles are tabulated. For $R_0 = 8$ kpc, the models have stellar mass $5 < M_* < 6 \\times 10^{10}$ M$_{\\odot}$, scale length $2.0 \\le R_d \\le 2.9$ kpc, LSR circular velocity $222 \\le \\Theta_0 \\le 233$ km s$^{-1}$, and solar circle stellar surface density $34 \\le \\Sigma_d(R_0) \\le 61$ M$_{\\odot}$ pc$^{-2}$. The present inter-arm location of the solar neighborhood may have a somewhat lower stellar surface density than average for the solar circle. The Milky Way appears to be a normal spiral galaxy that obeys scaling relations like the Tully-Fisher relation, the size-mass relation, and the disk maximality-surface brightness relation. The stellar disk is maximal, and the spiral arms are massive. The bumps and wiggles in the terminal velocity curve correspond to known spiral features (e.g., the Centaurus A...

  8. The influence of velocity and density ratio on the dynamics of spatially developing mixing layers

    Science.gov (United States)

    Strykowski, P. J.; Niccum, D. L.

    1992-04-01

    The dynamics of countercurrent mixing is examined in the shear layer of an axisymmetric jet. Experiments were designed to establish conditions of absolute instability in a spatially developing shear layer and to document how the instability influences the jet development. By applying suction around the jet periphery, shear-layer velocity ratios R greater than 1 could be studied. Here, R=(U1-U2)/(U1+U2), where U1 is the velocity of the forward jet stream and U2 is the velocity of the counterflowing stream created by suction. The density ratio S=ρ1/ρ2 of the mixing layer was also varied to determine the stability boundary in the S-R plane. The density of the forward stream ρ1 was increased by adding sulfur hexafluoride to the air jet, which provided density ratios between 1 and 5.1. Hot-wire anemometry and flow visualization revealed that a global transition occurs when conditions of absolute instability are established in the jet shear layers. One consequence of this transition is an abrupt decrease in the jet spread rate. The experimentally determined transition between globally stable and globally unstable flow regimes in the S-R plane agrees quite well with predictions of the convective/absolute instability boundary based on the linear stability theory [Pavithran and Redekopp, Phys. Fluids A 1, 1736 (1989)].

  9. Independent constraints on local non-Gaussianity from the peculiar velocity and density fields

    CERN Document Server

    Ma, Yin-Zhe; Scott, Douglas

    2013-01-01

    Primordial, non-Gaussian perturbations can generate scale-dependent bias in the galaxy distribution. This in turn will modify correlations between galaxy positions and peculiar velocities at late times, since peculiar velocities reflect the underlying matter distribution, whereas galaxies are a biased tracer of the same. We study this effect, and show that non-Gaussianity can be constrained by comparing the observed peculiar velocity field to a model velocity field reconstructed from the galaxy density field assuming linear bias. The amplitude of the spatial correlations in the residual map obtained after subtracting one velocity field from the other is directly proportional to the strength of the primordial non-Gaussianity. We construct the corresponding likelihood function use it to constrain the amplitude of the linear flow $\\beta$ and the amplitude of local non-Gaussianity $f^{NL}_{local}$. Applying our method to two observational data sets, the Type-Ia supernovae (A1SN) and Spiral Field \\textit{I}-band (...

  10. Temperature and density structure of a recurring active region jet

    Science.gov (United States)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-01-01

    Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, such as density, differential emission measure, peak temperature, velocity, and filling factor. Methods: A differential emission measure (DEM) analysis was performed at the region of the jet spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The resulting EIS DEM curves were compared to those obtained with AIA-XRT. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The predicted total count rates for each AIA channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the DEM inversion were investigated. Spectroscopic diagnostics were used to obtain an electron number density distribution for the jet spire and the jet footpoint. Results: The plasma along the line of sight in the jet spire and jet footpoint was found to be peak at 2.0 MK (log T [K] = 6.3). We calculated electron densities using the Fe XII (λ186/λ195) line ratio in the region of the spire (Ne = 7.6 × 1010 cm-3) and the footpoint (1.1 × 1011 cm-3). The plane-of-sky velocity of the jet is found to be 524 km s-1. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. The synthetic spectra contributing to each AIA channel confirms the multi-thermal nature of the AIA channels in both regions. There is no indication of high temperatures, such as emission from Fe XVII (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of the jet footpoint, synthetic spectra predict weak contributions from Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation, we confirmed

  11. Meson properties at finite temperature and baryon density

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M.; Klimt, S.; Weise, W. (Inst. of Theoretical Physics, Univ. Regensburg (Germany))

    1992-06-22

    We use the generalized SU(3) version of the Nambu and Jona-Lasinio model to discuss properties of mesons, constituent quarks and vacuum structure as a function of density and temperature in compressed matter. Systematic low-density expansions are derived. In particular, we show that effects due to finite quasi-particle size are important in stabilizing the density and temperature dependence of the pion mass. (orig.).

  12. Relative contributions of temperature and salinity to seasonal mixed layer density changes and horizontal density gradients

    OpenAIRE

    Johnson, Gregory C.; Schmidtko, Sunke; Lyman, John M.

    2012-01-01

    Temperature and salinity both contribute to ocean density, including its seasonal cycle and spatial patterns in the mixed layer. Temperature and salinity profiles from the Argo Program allow construction and analysis of a global, monthly, mixed layer climatology. Temperature changes dominate the seasonal cycle of mixed layer density in most regions, but salinity changes are dominant in the tropical warm pools, Arctic, and Antarctic. Under the Intertropical Convergence Zone, temperature and sa...

  13. Laminar Flame Velocity and Temperature Exponent of Diluted DME-Air Mixture

    Science.gov (United States)

    Naseer Mohammed, Abdul; Anwar, Muzammil; Juhany, Khalid A.; Mohammad, Akram

    2017-03-01

    In this paper, the laminar flame velocity and temperature exponent diluted dimethyl ether (DME) air mixtures are reported. Laminar premixed mixture of DME-air with volumetric dilutions of carbon dioxides (CO2) and nitrogen (N2) are considered. Experiments were conducted using a preheated mesoscale high aspect-ratio diverging channel with inlet dimensions of 25 mm × 2 mm. In this method, flame velocities are extracted from planar flames that were stabilized near adiabatic conditions inside the channel. The flame velocities are then plotted against the ratio of mixture temperature and the initial reference temperature. A non-linear power law regression is observed suitable. This regression analysis gives the laminar flame velocity at the initial reference temperature and temperature exponent. Decrease in the laminar flame velocity and increase in temperature exponent is observed for CO2 and N2 diluted mixtures. The addition of CO2 has profound influence when compared to N2 addition on both flame velocity and temperature exponent. Numerical prediction of the similar mixture using a detailed reaction mechanism is obtained. The computational mechanism predicts higher magnitudes for laminar flame velocity and smaller magnitudes of temperature exponent compared to experimental data.

  14. Mass, velocity anisotropy, and pseudo phase-space density profiles of Abell 2142

    Science.gov (United States)

    Munari, E.; Biviano, A.; Mamon, G. A.

    2014-06-01

    Aims: We aim to compute the mass and velocity anisotropy profiles of Abell 2142 and, from there, the pseudo phase-space density profile Q(r) and the density slope - velocity anisotropy β - γ relation, and then to compare them with theoretical expectations. Methods: The mass profiles were obtained by using three techniques based on member galaxy kinematics, namely the caustic method, the method of dispersion-kurtosis, and MAMPOSSt. Through the inversion of the Jeans equation, it was possible to compute the velocity anisotropy profiles. Results: The mass profiles, as well as the virial values of mass and radius, computed with the different techniques agree with one another and with the estimates coming from X-ray and weak lensing studies. A combined mass profile is obtained by averaging the lensing, X-ray, and kinematics determinations. The cluster mass profile is well fitted by an NFW profile with c = 4.0 ± 0.5. The population of red and blue galaxies appear to have a different velocity anisotropy configuration, since red galaxies are almost isotropic, while blue galaxies are radially anisotropic, with a weak dependence on radius. The Q(r) profile for the red galaxy population agrees with the theoretical results found in cosmological simulations, suggesting that any bias, relative to the dark matter particles, in velocity dispersion of the red component is independent of radius. The β - γ relation for red galaxies matches the theoretical relation only in the inner region. The deviations might be due to the use of galaxies as tracers of the gravitational potential, unlike the non-collisional tracer used in the theoretical relation.

  15. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    CERN Document Server

    Grisdale, Kearn; Romeo, Alessandro B; Renaud, Florent; Read, Justin I

    2016-01-01

    We study the role of stellar feedback in shaping the density and velocity structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry out $\\sim 4.6$ pc resolution $N$-body+adaptive mesh refinement (AMR) hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way (MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed HI in local spiral galaxies from THINGS (The HI Nearby Galaxy Survey). We find that observed HI density power spectra is only reproduced by simulations with efficient stellar feedback, which influences the gas density field up to large (kpc) scales. Furthermore, the kinetic energy power spectra in feedback regulated galaxies, regardless of galaxy mass and size, show scalings in excellent agreement with super-sonic turbulence ($E(k)\\propto k^{-2})$ on scales below the thickness of the HI layer. This is in stark contrast to ...

  16. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films.

    Science.gov (United States)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  17. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S [CNR-INFM Laboratorio Regionale SuperMat, Via Salvador Allende, I-84081 Baronissi (Italy)], E-mail: grimaldi@sa.infn.it

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  18. Binding Energy Calculation of Electrons in Statistical Potentials for Arbitrary Temperature and Matter Density

    Institute of Scientific and Technical Information of China (English)

    SunYongsheng; MengXujun

    1990-01-01

    Schroedinger's wave equation is solved in Thomas-Fermi potential including the self-interaction modification of elctrons for arbitrary matter density and temperature,In order to describe relativistic effects,the mass-velocity correction,the Darwin correction and the spin-orbit coupling terms are included in the wave equation.Calculations are presented for the Fe26 and Rb37 atoms at a few temperatures and matter densities.Comparisons of present results with other more accurate one[9] are given in Table.The data obtained by the present method are not bad.

  19. Velocity of density shifts in Finnish landbird species depends on their migration ecology and body mass.

    Science.gov (United States)

    Välimäki, Kaisa; Lindén, Andreas; Lehikoinen, Aleksi

    2016-05-01

    A multitude of studies confirm that species have changed their distribution ranges towards higher elevations and towards the poles, as has been predicted by climate change forecasts. However, there is large interspecific variation in the velocity of range shifts. From a conservation perspective, it is important to understand which factors explain variation in the speed and the extent of range shifts, as these might be related to the species' extinction risk. Here, we study shifts in the mean latitude of occurrence, as weighted by population density, in different groups of landbirds using 40 years of line transect data from Finland. Our results show that the velocity of such density shifts differed among migration strategies and increased with decreasing body size of species, while breeding habitat had no influence. The slower velocity of large species could be related to their longer generation time and lower per capita reproduction that can decrease the dispersal ability compared to smaller species. In contrast to some earlier studies of range margin shifts, resident birds and partial migrants showed faster range shifts, while fully migratory species were moving more slowly. The results suggest that migratory species, especially long-distance migrants, which often show decreasing population trends, might also have problems in adjusting their distribution ranges to keep pace with global warming.

  20. Mass, velocity anisotropy and pseudo phase space density profiles of Abell 2142

    CERN Document Server

    Munari, Emiliano; Mamon, Gary

    2013-01-01

    Aim: We aim to compute the mass and velocity anisotropy profiles of Abell 2142 and, from there, the pseudo phase space density profile $Q(r)$ and the density slope - velocity anisotropy $\\beta - \\gamma$ relation, and compare them with theoretical expectations. Methods: The mass profiles have been obtained by using three techniques based on member galaxy kinematics, namely the caustic method, the method of Dispersion - Kurtosis and MAMPOSSt. Through the inversion of the Jeans equation it has been possible to compute the velocity anisotropy profiles. Results: The mass profiles, as well as the virial values of mass and radius, computed with the different techniques are in agreement with one another and with the estimates coming from X-ray and weak lensing studies. A concordance mass profile is obtained by averaging the lensing, X-ray and kinematics determinations. The cluster mass profile is well fit by an NFW profile with $c=4.0 \\pm 0.5$. The population of red and blue galaxies appear to have a different veloci...

  1. 3D Velocity and Density Reconstructions of the Local Universe with Cosmicflows-1

    CERN Document Server

    Courtois, Helene M; Tully, R Brent; Gottlober, Stefan

    2011-01-01

    This paper presents an analysis of the local peculiar velocity field based on the Wiener Filter reconstruction method. We used our currently available catalog of distance measurements containing 1,797 galaxies within 3000 km/s: Cosmicflows-1. The Wiener Filter method is used to recover the full 3D peculiar velocity field from the observed map of radial velocities and to recover the underlying linear density field. The velocity field within a data zone of 3000 km/s is decomposed into a local component that is generated within the data zone and a tidal one that is generated by the mass distribution outside that zone. The tidal component is characterized by a coherent flow toward the Norma-Hydra-Centaurus (Great Attractor) region while the local component is dominated by a flow toward the Virgo Cluster and away from the Local Void. A detailed analysis shows that the local flow is predominantly governed by the Local Void and the Virgo Cluster plays a lesser role. The analysis procedure was tested against a mock c...

  2. Temperature Dependence of Sound Velocity in High-Strength Fiber-Reinforced Plastics

    Science.gov (United States)

    Nomura, Ryuji; Yoneyama, Keiichi; Ogasawara, Futoshi; Ueno, Masashi; Okuda, Yuichi; Yamanaka, Atsuhiko

    2003-08-01

    Longitudinal sound velocity in unidirectional hybrid composites or high-strength fiber-reinforced plastics (FRPs) was measured along the fiber axis over a wide temperature range (from 77 K to 420 K). We investigated two kinds of high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which are known to have negative thermal expansion coefficients and high thermal conductivities along the fiber axis. Both FRPs had very high sound velocities of about 9000 m/s at low temperatures and their temperature dependences were very strong. Sound velocity monotonically decreased with increasing temperature. The temperature dependence of sound velocity was much stronger in Dyneema-FRP than in Zylon-FRP.

  3. Effect of temperature on electrophoresis velocity of sol particles in water

    Institute of Scientific and Technical Information of China (English)

    鲍治宇; 顾大明

    2002-01-01

    Viscosity of water is affected by temperature and electrophoresis velocity is related to the viscosity of colloid. However, there hasn' t been any direct description about the relation between electrophoresis velocity of colloid and temperature. Based on a large number of tests, the relation between electrophoresis velocity and temperature is established as [ v = A + B( T-T°) ]. Meanwhile the ratio of the electric charge (q) of sol particles to their radium (r) is a constant is obtained. The results of above were testified in both experiment and theory.

  4. Velocity-density correlations from the cosmicflows-3 distance catalogue and the 2MASS Redshift Survey

    Science.gov (United States)

    Nusser, Adi

    2017-09-01

    The peculiar velocity of a mass tracer is on average aligned with the dipole modulation of the surrounding mass density field. We present a first measurement of the correlation between radial peculiar velocities of objects in the cosmicflows-3 catalogue and the dipole moment of the 2MRS galaxy distribution in concentric spherical shells centred on these objects. Limiting the analysis to cosmicflows-3 objects with distances of 100h-1 Mpc, the correlation function is detected at a confidence level of ≳ 4σ. The measurement is found consistent with the standard ΛCDM model at the ≲ 1.7σ level. We formally derive the constraints 0.32 confidence level) or equivalently 0.34 type of correlations.

  5. Mapping Metal-Enriched High Velocity Clouds to Very Low HI Column Densities

    CERN Document Server

    Churchill, C W; Masiero, J R; Churchill, Chris; Charlton, Jane

    2001-01-01

    Our galaxy is the nearest known quasar absorption line system, and it uniquely provides us with an opportunity to probe multiple lines of sight through the same galaxy. This is essential for our interpretations of the complex kinematic profiles seen in the MgII absorption due to lines of sight through intermediate redshift galaxies. The Milky Way halo has never been probed for high velocity clouds below the 21-cm detection threshold of N(HI)~10^18 cm-2. Through a survey of MgII absorption looking toward the brightest AGNs and quasars, it will be possible to reach down a few orders of magnitude in HI column density. The analogs to the high velocity components of the MgII absorption profiles due to intermediate redshift galaxies should be seen. We describe a program we are undertaking, and present some preliminary findings.

  6. A microscopic "social norm" model to obtain realistic macroscopic velocity and density pedestrian distributions.

    Directory of Open Access Journals (Sweden)

    Francesco Zanlungo

    Full Text Available We propose a way to introduce in microscopic pedestrian models a "social norm" in collision avoiding and overtaking, i.e. the tendency, shared by pedestrians belonging to the same culture, to avoid collisions and perform overtaking in a preferred direction. The "social norm" is implemented, regardless of the specific collision avoiding model, as a rotation in the perceived velocity vector of the opponent at the moment of computation of the collision avoiding strategy, and justified as an expectation that the opponent will follow the same "social norm" (for example a tendency to avoid on the left and overtake on the right, as proposed in this work for Japanese pedestrians. By comparing with real world data, we show that the introduction of this norm allows for a better reproduction of macroscopic pedestrian density and velocity patterns.

  7. [Comparison of force and shortening velocity in fast and slow rabbit muscle fibers at different temperatures].

    Science.gov (United States)

    Kochubeĭ, P V; Bershitskiĭ, S Iu

    2014-01-01

    The temperature dependence of force, maximal shortening velocity and power of maximally activated single permeabilized fibers from fast and slow muscles of the rabbit were recorded in a temperature range from 10 to 35 degrees C with 5 degrees C step. It was found that temperature dependence of force of both types of fibers is identical. Averaged maximal shortening velocity in the slow fibers, unlike the fast fibers, had no statistically significant temperature dependence that is not in agreement with the data obtained on intact rat muscle fibers and in an in vitro motility assay. However maximal shortening velocity in each individual slow fiber did depend on temperature. The temperature dependence of power of the slow fibers was lower than that of the fast ones. Because of large data scattering the average temperature dependence of power of the slow fibers was significantly lower than that in individual slow fibers.

  8. Cosmological Density and Power Spectrum from Peculiar Velocities Nonlinear Corrections and PCA

    CERN Document Server

    Silberman, L; Eldar, A; Zehavi, I

    2001-01-01

    we allow for nonlinear effects in the likelihood analysis of galaxy peculiar velocities, and obtain ~35%-lower values for the cosmological density parameter and for the amplitude of mass-density fluctuations. The power spectrum in the linear regime is assumed to be a flat LCDM model (h=0.65, n=1, COBE) with only Om_m as a free parameter. Since the likelihood is driven by the nonlinear regime, we "break" the power spectrum at k_b=0.2 h/Mpc and fit a power law at k>k_b. This allows for independent matching of the nonlinear behavior and an unbiased fit in the linear regime. The analysis assumes Gaussian fluctuations and errors, and a linear relation between velocity and density. Tests using mock catalogs that properly simulate nonlinear effects demonstrate that this procedure results in a reduced bias and a better fit. We find for the Mark3 and SFI data Om_m=0.32+-0.06 and 0.37+-0.09 respectively, with sigma_8*Om_m^0.6 =0.49+-0.06 and 0.63+-0.08, in agreement with constraints from other data. The quoted 90% erro...

  9. Amplified spontaneous emission of phonons as a likely mechanism for density-dependent velocity saturation in GaN transistors

    Science.gov (United States)

    Khurgin, Jacob B.; Bajaj, Sanyam; Rajan, Siddharth

    2016-09-01

    We show that density-dependent velocity saturation in a GaN high electron mobility transistor (HEMT) can be related to the stimulated emission of longitudinal optical (LO) phonons. As the drift velocity of electrons increases, the drift of the Fermi distribution in reciprocal space results in population inversion and gain for the LO phonons. Once this gain reaches a threshold value, the avalanche-like increase in LO phonon emission causes a rapid loss of electron energy and momentum and leads to drift velocity saturation. Our simple model correctly predicts both the general trend of decreasing saturation velocity with increasing electron density, and the measured experimental values of saturation.

  10. Determination of coronal temperatures from electron density profiles

    CERN Document Server

    Lemaire, J F

    2011-01-01

    The most popular method for determining coronal temperatures is the scale-height-method (shm). It is based on electron density profiles inferred from White Light (WL) brightness measurements of the corona during solar eclipses. This method has been applied to several published coronal electron density models. The calculated temperature distributions reach a maximum at r > 1.3 RS, and therefore do not satisfy one of the conditions for applying the shm method. Another method is the hydrostatic equilibrium method (hst), which enables coronal temperature distributions to be determined, providing solutions to the hydrostatic equilibrium equation. The temperature maximas using the hst method are almost equal to those obtained using the shm method, but the temperature peak is always at significantly lower altitude when the hst-method is used than when the shm-method is used. A third and more recently developed method, dyn, can be used for the same published electron density profiles. The temperature distributions ob...

  11. Velocity and Temperature Distribution in Flow from an Inlet Device in Rooms with Displacement Ventilation

    DEFF Research Database (Denmark)

    Jacobsen, T.V.; Nielsen, Peter V.

    Measurements are performed in a full-scale test room with displacement ventilation with focus on the velocity and temperature field in the region close to the inlet device. Investigations based on these detailed measurements have been made in order to see if it is possible to describe the velocity...

  12. The three-dimensional distributions of tangential velocity and total- temperature in vortex tubes

    DEFF Research Database (Denmark)

    Linderstrøm-Lang, C.U.

    1971-01-01

    physical requirements and which at the same time lead to realistic tangential velocity gradients. The total-temperature distribution in both the axial and radial directions is calculated from such secondary flow functions and corresponding tangential velocity results on the basis of an approximate...

  13. Flow rate of particles through apertures obtained from self-similar density and velocity profiles

    OpenAIRE

    2012-01-01

    ‘‘Beverloo’s law’’ is considered as the standard expression to estimate the flow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justified. In this Letter, we study the density and velocity profiles in the flow of particles through an aperture. We find that, for the whole range of apertures studied, both profiles are self-similar. Hence, by means of the functionality obtained for the...

  14. The effect of air velocity on heat stress at increased air temperature

    DEFF Research Database (Denmark)

    Bjerg, Bjarne Schmidt; Wang, Xiaoshuai; Zhang, Guoqiang

    to the temperature difference between the surfaces of animals and the surrounding air, and this temperature difference declines when the air temperature approaches the animal body temperature. Consequently it can it by expected that the effect of air velocity decreases at increased air temperature. The literature...... constant. Generally usable values for two of these constants were suggested but more work is required to determine how the third constant depends on different conditions including realistic farm conditions....

  15. Force-free collisionless current sheet models with non-uniform temperature and density profiles

    Science.gov (United States)

    Wilson, F.; Neukirch, T.; Allanson, O.

    2017-09-01

    We present a class of one-dimensional, strictly neutral, Vlasov-Maxwell equilibrium distribution functions for force-free current sheets, with magnetic fields defined in terms of Jacobian elliptic functions, extending the results of Abraham-Shrauner [Phys. Plasmas 20, 102117 (2013)] to allow for non-uniform density and temperature profiles. To achieve this, we use an approach previously applied to the force-free Harris sheet by Kolotkov et al. [Phys. Plasmas 22, 112902 (2015)]. In one limit of the parameters, we recover the model of Kolotkov et al. [Phys. Plasmas 22, 112902 (2015)], while another limit gives a linear force-free field. We discuss conditions on the parameters such that the distribution functions are always positive and give expressions for the pressure, density, temperature, and bulk-flow velocities of the equilibrium, discussing the differences from previous models. We also present some illustrative plots of the distribution function in velocity space.

  16. Vortex line density in counterflowing He II with laminar and turbulent normal fluid velocity profiles

    CERN Document Server

    Baggaley, A W

    2013-01-01

    Superfluid helium is an intimate mixture of a viscous normal fluid, with continuous vorticity, and an inviscid superfluid, where vorticity is constrained to thin, stable topological defects. One mechanism to generate turbulence in this system is through the application of a heat flux, so called thermal counterflow. Of particular interest is how turbulence in the superfluid responds to both a laminar and turbulent normal fluid in the presence of walls. We model superfluid vortex lines as reconnecting space curves with fixed circulation, and consider both laminar (Poiseuille) and turbulent normal fluid flows in a channel configuration. Using high resolution numerical simulations we show that turbulence in the normal fluid sustains a notably higher vortex line density than a laminar flow with the same mean flow rate. We exam Vinen's relation, $\\sqrt{L}=\\gamma v_{ns}$, between the steady state vortex line density $L$ and the counterflow velocity $v_{ns}$. Our results support the hypothesis that transition to turb...

  17. Effect of transverse velocity and temperature gradients on sound attenuation in two-dimensional ducts

    Science.gov (United States)

    Nayfeh, A. H.; Sun, J.

    1974-01-01

    An investigation is described of the effect of transverse mean-velocity and temperature gradients on sound attenuation in acoustically treated two-dimensional ducts. The results show that cooling the duct walls leads to channeling the sound toward the walls for both downstream and upstream propagation. The effect of mean-temperature gradients on the attenuation rates of the lowest three modes can be as important as the effect of mean-velocity gradients.

  18. DECAY OF VORTEX VELOCITY AND DIFFUSION OF TEMPERATURE IN A GENERALIZED SECOND GRADE FLUID

    Institute of Scientific and Technical Information of China (English)

    SHEN Fang 沈芳; TAN Wen-chang 谭文长; ZHAO Yao-hua 赵耀华; T. Masuoka T·增冈隆士

    2004-01-01

    The fractional calculus approach in the constitutive relationship model of viscoelastic fluid was introduced. The velocity and temperature fields of the vortex flow of a generalized second fluid with fractional derivative model were described by fractional partial differential equations. Exact analytical solutions of these differential equations were obtained by using the discrete Laplace transform of the sequential fractional derivatives and generalized Mittag-Leffler function. The influence of fractional coefficient on the decay of vortex velocity and diffusion of temperature was also analyzed.

  19. Temperature Dependence Viscosity and Density of Different Biodiesel Blends

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2015-01-01

    Full Text Available The main goal of this paper is to assess the effect of rapeseed oil methyl ester (RME concentration in diesel fuel on its viscosity and density behaviour. The density and dynamic viscosity were observed at various mixing ratios of RME and diesel fuel. All measurements were performed at constant temperature of 40 °C. Increasing ratio of RME in diesel fuel was reflected in increased density value and dynamic viscosity of the blend. In case of pure RME, pure diesel fuel, and a blend of both (B30, temperature dependence of dynamic viscosity and density was examined. Temperature range in the experiment was −10 °C to 80 °C. Considerable temperature dependence of dynamic viscosity and density was found and demonstrated for all three samples. This finding is in accordance with theoretical assumptions and reference data. Mathematical models were developed and tested. Temperature dependence of dynamic viscosity was modeled using a polynomial 3rd polynomial degree. Correlation coefficients R −0.796, −0.948, and −0.974 between measured and calculated values were found. Temperature dependence of density was modeled using a 2nd polynomial degree. Correlation coefficients R −0.994, −0.979, and −0.976 between measured and calculated values were acquired. The proposed models can be used for flow behaviour prediction of RME, diesel fuel, and their blends.

  20. Plasmaspheric H+, He+, O+, He++, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, D. L.; Craven, P. D.; Comfort H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  1. Plasmaspheric H+, He+, He++, O+, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, G. L.; Craven, P. D.; Comfort, R. H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  2. Evolution of density and velocity profiles of dark matter and dark energy in spherical voids

    Science.gov (United States)

    Novosyadlyj, Bohdan; Tsizh, Maksym; Kulinich, Yurij

    2017-02-01

    We analyse the evolution of cosmological perturbations which leads to the formation of large isolated voids in the Universe. We assume that initial perturbations are spherical and all components of the Universe (radiation, matter and dark energy) are continuous media with ideal fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations for every component in the comoving to cosmological background reference frame are obtained from equations of energy and momentum conservation and Einstein's ones and are integrated numerically. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is much larger than the particle horizon. Results show how the profiles of density and velocity of matter and dark energy are formed and how they depend on parameters of dark energy and initial conditions. In particular, it is shown that final matter density and velocity amplitudes change within range ˜4-7 per cent when the value of equation-of-state parameter of dark energy w vary in the range from -0.8 to -1.2, and change within ˜1 per cent only when the value of effective sound speed of dark energy vary over all allowable range of its values.

  3. Phonon Density of States and Sound Velocities of an Iron-Nickel Alloy at High Pressure

    Science.gov (United States)

    Miller, R. A.; Jackson, J. M.; Sturhahn, W.; Murphy, C. A.

    2012-12-01

    Seismological and cosmochemical studies suggest Earth's core is primarily composed of iron with ~5 to 10 wt% nickel and some light elements [e.g., 1]. Therefore, understanding the behavior of Fe-Ni alloys at high pressure is important for interpreting seismic data and for modeling the interior of the Earth. While many studies have investigated the properties of pure Fe at high pressure, the elastic and vibrational properties of Fe-Ni alloys at high pressure are not well known. We measured sound velocities and thermodynamic properties of 95%-enriched 57Fe alloyed with 10 wt% Ni at high-pressures in a Ne pressure medium. Measurements of high statistical quality were performed with nuclear resonant inelastic x-ray scattering (NRIXS) at 3ID-B of the Advanced Photon Source [e.g., 2 & 3]. The sample volume was determined at each compression point with in-line x-ray diffraction at 3ID-B before and after each NRIXS measurement. In this contribution, we will present derived partial phonon density of states, Debye sound velocities, and compressional and shear sound velocities for Fe0.9-Ni0.1 at high-pressures. [1] McDonough, W.F. (2004): Compositional Model for the Earth's Core. Elsevier Ltd., Oxford. [2] Murphy, C.A., J.M. Jackson, W. Sturhahn, and B. Chen (2011): Melting and thermal pressure of hcp-Fe from the phonon density of states, Phys. Earth Planet. Int., doi:10.1016/j.pepi.2011.07.001. [3] Murphy, C.A., J.M. Jackson, W. Sturhahn, and B. Chen (2011): Grüneisen parameter of hcp-Fe to 171 GPa, Geophys. Res. Lett., doi:10.1029/2011GL049531.

  4. Particle Size, Number Density, And Velocity Measurements In A 2800 K Combustion System

    Science.gov (United States)

    Farmer, W. M.; Schwartz, F. A.; Stallings, E. S.; Belz, R. A.

    1983-10-01

    Particle size and velocity measurements have been obtained in a low-speed (6 to 10 m/s), 2800 K combustor 30 cm in diameter. The measurements were obtained using a particle-sizing interferometer coupled to a 0.5 m spectrometer for background light rejection from radiant particles. Results obtained for the combustion of powdered coke clearly indicate the capabilities of this type of instrument to estimate combustor efficiency as a function of temperature. Comparison of the optically sampled measurements with other sampling techniques shows reasonable agreement.

  5. Temperature dependence of densities of Sb and Bi melts

    Institute of Scientific and Technical Information of China (English)

    GENG HaoRan; SUN ChunJing; WANG Rui; QI XiaoGang; ZHANG Ning

    2007-01-01

    The densities of Sb and Bi melts were investigated by an improved Archimedean method. The results show that the density of the Sb melt decreases linearly with increasing temperature, but the density of the Bi melt firstly increases and then decreases as the temperature increases. There is a maximum density value of 10.002 g/cm3 at 310℃, about 39℃ above the melting point. The temperature dependence of the Sb melt is well fitted with the expression ρ= 6.8590-5.8105×10-4T, and that of the Bi melt is fitted with ρ=10.3312-1.18×10-3T. The results were discussed from a microstructure viewpoint.

  6. Density of biogas digestate depending on temperature and composition.

    Science.gov (United States)

    Gerber, Mandy; Schneider, Nico

    2015-09-01

    Density is one of the most important physical properties of biogas digestate to ensure an optimal dimensioning and a precise design of biogas plant components like stirring devices, pumps and heat exchangers. In this study the density of biogas digestates with different compositions was measured using pycnometers at ambient pressure in a temperature range from 293.15 to 313.15K. The biogas digestates were taken from semi-continuous experiments, in which the marine microalga Nannochloropsis salina, corn silage and a mixture of both were used as feedstocks. The results show an increase of density with increasing total solid content and a decrease with increasing temperature. Three equations to calculate the density of biogas digestate were set up depending on temperature as well as on the total solid content, organic composition and elemental composition, respectively. All correlations show a relative deviation below 1% compared to experimental data.

  7. Baryon number fluctuations at finite temperature and density

    CERN Document Server

    Fu, Wei-jie; Rennecke, Fabian; Schaefer, Bernd-Jochen

    2016-01-01

    We investigate baryon number fluctuations for finite temperature and density in two-flavor QCD. This is done within a QCD-improved low-energy effective theory in an extension of the approach put forward in [1,2]. In the present work we aim at improving the predictive power of this approach for large temperatures and density, that is, for small collision energies. This is achieved by taking into account the full frequency dependence of the quark dispersion. This ensures the necessary Silver Blaze property of finite density QCD for the first time, which so far was only implemented approximately. Moreover, we show that Polyakov loop fluctuations have a sizeable impact at large temperatures and density. The results for the kurtosis of baryon number fluctuations are compared to previous effective theory results, lattice results and recent experimental data from STAR.

  8. Experimental study of stratified jet by simultaneous measurements of velocity and density fields

    Science.gov (United States)

    Xu, Duo; Chen, Jun

    2012-07-01

    Stratified flows with small density difference commonly exist in geophysical and engineering applications, which often involve interaction of turbulence and buoyancy effect. A combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) system is developed to measure the velocity and density fields in a dense jet discharged horizontally into a tank filled with light fluid. The illumination of PIV particles and excitation of PLIF dye are achieved by a dual-head pulsed Nd:YAG laser and two CCD cameras with a set of optical filters. The procedure for matching refractive indexes of two fluids and calibration of the combined system are presented, as well as a quantitative analysis of the measurement uncertainties. The flow structures and mixing dynamics within the central vertical plane are studied by examining the averaged parameters, turbulent kinetic energy budget, and modeling of momentum flux and buoyancy flux. At downstream, profiles of velocity and density display strong asymmetry with respect to its center. This is attributed to the fact that stable stratification reduces mixing and unstable stratification enhances mixing. In stable stratification region, most of turbulence production is consumed by mean-flow convection, whereas in unstable stratification region, turbulence production is nearly balanced by viscous dissipation. Experimental data also indicate that at downstream locations, mixing length model performs better in mixing zone of stable stratification regions, whereas in other regions, eddy viscosity/diffusivity models with static model coefficients represent effectively momentum and buoyancy flux terms. The measured turbulent Prandtl number displays strong spatial variation in the stratified jet.

  9. Penetrative convection in stratified fluids: velocity and temperature measurements

    Directory of Open Access Journals (Sweden)

    M. Moroni

    2006-01-01

    Full Text Available The flux through the interface between a mixing layer and a stable layer plays a fundamental role in characterizing and forecasting the quality of water in stratified lakes and in the oceans, and the quality of air in the atmosphere. The evolution of the mixing layer in a stably stratified fluid body is simulated in the laboratory when "Penetrative Convection" occurs. The laboratory model consists of a tank filled with water and subjected to heating from below. The methods employed to detect the mixing layer growth were thermocouples for temperature data and two image analysis techniques, namely Laser Induced Fluorescence (LIF and Feature Tracking (FT. LIF allows the mixing layer evolution to be visualized. Feature Tracking is used to detect tracer particle trajectories moving within the measurement volume. Pollutant dispersion phenomena are naturally described in the Lagrangian approach as the pollutant acts as a tag of the fluid particles. The transilient matrix represents one of the possible tools available for quantifying particle dispersion during the evolution of the phenomenon.

  10. Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device

    Science.gov (United States)

    Chakraborty Thakur, S.; Adriany, K.; Gosselin, J. J.; McKee, J.; Scime, E. E.; Sears, S. H.; Tynan, G. R.

    2016-11-01

    We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities.

  11. Two is better than one: joint statistics of density and velocity in concentric spheres as a cosmological probe

    Science.gov (United States)

    Uhlemann, C.; Codis, S.; Hahn, O.; Pichon, C.; Bernardeau, F.

    2017-08-01

    The analytical formalism to obtain the probability distribution functions (PDFs) of spherically averaged cosmic densities and velocity divergences in the mildly non-linear regime is presented. A large-deviation principle is applied to those cosmic fields assuming their most likely dynamics in spheres is set by the spherical collapse model. We validate our analytical results using state-of-the-art dark matter simulations with a phase-space resolved velocity field finding a 2 per cent level agreement for a wide range of velocity divergences and densities in the mildly non-linear regime (∼10 Mpc h-1 at redshift zero), usually inaccessible to perturbation theory. From the joint PDF of densities and velocity divergences measured in two concentric spheres, we extract with the same accuracy velocity profiles and conditional velocity PDF subject to a given over/underdensity that are of interest to understand the non-linear evolution of velocity flows. Both PDFs are used to build a simple but accurate maximum likelihood estimator for the redshift evolution of the variance of both the density and velocity divergence fields, which have smaller relative errors than their sample variances when non-linearities appear. Given the dependence of the velocity divergence on the growth rate, there is a significant gain in using the full knowledge of both PDFs to derive constraints on the equation of state-of-dark energy. Thanks to the insensitivity of the velocity divergence to bias, its PDF can be used to obtain unbiased constraints on the growth of structures (σ8, f) or it can be combined with the galaxy density PDF to extract bias parameters.

  12. Method of temperature rising velocity and threshold control of electron beam brazing

    Institute of Scientific and Technical Information of China (English)

    Xuedong Wang; Shun Yao

    2005-01-01

    In order to accommodate electron beam to the brazing of the joints with various curve shapes and the brazing of thermo sensitive materials, the method of electron beam scanning and brazing temperature control was developed, in which electron beam was controlled to scan according to predefined scanning track, and the actual temperature rising velocity of the brazed seam was limited in an allowed scope by detecting the brazed seam temperature, calculating the temperature rising velocity and adjusting the beam current during the brazing process; in addition, through the setting of the highest allowed temperature, the actual temperature of the brazed seam could be controlled not exceeding the threshold set value, and these two methods could be employed alone or jointly. It is shown that high precision temperature control in electron beam brazing could be realized and the productivity be increased by the proposed method.

  13. The density and velocity of plasma bullets propagating along one dielectric tube

    Directory of Open Access Journals (Sweden)

    Longfei Ji

    2015-08-01

    Full Text Available This study shows that the propagation of plasma bullets along one dielectric tube is strongly affected by many discharge parameters, such as the waveform of applied voltage (AC or pulsed DC, peak voltage, He flow rate, and the frequency of AC voltage. Analysis indicates that the density and velocity of plasma bullets are mainly determined by the electric field at the front of plasma bullets. These discharge parameters may significantly influence the distribution of plasma potential along the tube, thus control the electric field at the front of plasma bullets and their propagation. An increase in the pulsed DC voltage with its rise time of <40-50 ns can lead to an obvious improvement in the electric field at the front of plasma bullets, resulting in generation of a plasma in the high density gas and a fast propagation of plasma bullets. He flowing through the tube can contribute to the surface diffusion of charged species, and greatly increase the electric field at the front of plasma bullets. During the propagation of plasma bullets, their density is decreased due to the surface recombination of charged species, such as electrons and ions.

  14. Influence of stem temperature changes on heat pulse sap flux density measurements.

    Science.gov (United States)

    Vandegehuchte, Maurits W; Burgess, Stephen S O; Downey, Alec; Steppe, Kathy

    2015-04-01

    While natural spatial temperature gradients between measurement needles have been thoroughly investigated for continuous heat-based sap flow methods, little attention has been given to how natural changes in stem temperature impact heat pulse-based methods through temporal rather than spatial effects. By modelling the theoretical equation for both an ideal instantaneous pulse and a step pulse and applying a finite element model which included actual needle dimensions and wound effects, the influence of a varying stem temperature on heat pulse-based methods was investigated. It was shown that the heat ratio (HR) method was influenced, while for the compensation heat pulse and Tmax methods changes in stem temperatures of up to 0.002 °C s(-1) did not lead to significantly different results. For the HR method, rising stem temperatures during measurements led to lower heat pulse velocity values, while decreasing stem temperatures led to both higher and lower heat pulse velocities, and to imaginary results for high flows. These errors of up to 40% can easily be prevented by including a temperature correction in the data analysis procedure, calculating the slope of the natural temperature change based on the measured temperatures before application of the heat pulse. Results of a greenhouse and outdoor experiment on Pinus pinea L. show the influence of this correction on low and average sap flux densities.

  15. Density and Temperature Measurements in a Solar Active Region

    Science.gov (United States)

    Warren, Harry P.; Winebarger, Amy R.

    2003-10-01

    We present electron density and temperature measurements from an active region observed above the limb with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory. Density-sensitive line ratios from Si VIII and S X indicate densities greater than 108 cm-3 as high as 200" (or 145 Mm) above the limb. At these heights, static, uniformly heated loop models predict densities close to 107 cm-3. Differential emission measure analysis shows that the observed plasma is nearly isothermal with a mean temperature of about 1.5 MK and a dispersion of about 0.2 MK. Both the differential emission measure and the Si XI/Si VIII line ratios indicate only small variations in the temperature at the heights observed. These measurements confirm recent observations from the Transition Region and Coronal Explorer of ``overdense'' plasma at temperatures near 1 MK in solar active regions. Time-dependent hydrodynamic simulations suggest that impulsive heating models can account for the large densities, but they have a difficult time reproducing the narrow range of observed temperatures. The observations of overdense, nearly isothermal plasma in the solar corona provide a significant challenge to theories of coronal heating.

  16. Two is better than one: joint statistics of density and velocity in concentric spheres as a cosmological probe

    CERN Document Server

    Uhlemann, Cora; Hahn, Oliver; Pichon, Christophe; Bernardeau, Francis

    2016-01-01

    The analytical formalism to obtain the probability distribution functions (PDFs) of spherically-averaged cosmic densities and velocity divergences in the mildly non-linear regime is presented. A large-deviation principle is applied to those cosmic fields assuming their most likely dynamics in spheres is set by the spherical collapse model. We validate our analytical results using state-of-the-art dark matter simulations with a phase-space resolved velocity field finding a 2% percent level agreement for a wide range of velocity divergences and densities in the mildly nonlinear regime (~10Mpc/h at redshift zero), usually inaccessible to perturbation theory. From the joint PDF of densities and velocity divergences measured in two concentric spheres, we extract with the same accuracy velocity profiles and conditional velocity PDF subject to a given over/under-density which are of interest to understand the non-linear evolution of velocity flows. Both PDFs are used to build a simple but accurate maximum likelihood...

  17. Evolution of density and velocity profiles of matter in large voids

    CERN Document Server

    Tsizh, Maksym

    2016-01-01

    We analyse the evolution of cosmological perturbations which leads to the formation of large voids in the distribution of galaxies. We assume that perturbations are spherical and all components of the Universe - radiation, matter and dark energy - are continuous media with ideal fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations in the comoving to cosmological background reference frame for every component are obtained from equations of conservation and Einstein's ones and are integrated by modified Euler method. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is mush larger than the particle horizon. Results show how the profiles of density and velocity of matter in spherical voids with different overdensity shells are formed.

  18. Evolution of density and velocity profiles of matter in large voids

    Science.gov (United States)

    Tsizh, M.; Novosyadlyj, B.

    2016-09-01

    We analyse the evolution of cosmological perturbations which leads to the formation of large voids in the distribution of galaxies. We assume that perturbations are spherical and all components of the Universe - radiation, matter and dark energy - are continuous media with ideal fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations in the comoving to cosmological background reference frame for every component are obtained from equations of conservation and Einstein's ones and are integrated by modified Euler method. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is mush larger than the particle horizon. Results show how the profiles of density and velocity of matter in spherical voids with different overdensity shells are formed.

  19. Flow Rate of Particles through Apertures Obtained from Self-Similar Density and Velocity Profiles

    Science.gov (United States)

    Janda, Alvaro; Zuriguel, Iker; Maza, Diego

    2012-06-01

    “Beverloo’s law” is considered as the standard expression to estimate the flow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justified. In this Letter, we study the density and velocity profiles in the flow of particles through an aperture. We find that, for the whole range of apertures studied, both profiles are self-similar. Hence, by means of the functionality obtained for them the mass flow rate is calculated. The comparison of this expression with the Beverloo’s one reveals some differences which are crucial to understanding the mechanism that governs the flow of particles through orifices.

  20. Characterization of size, anisotropy, and density heterogeneity of nanoparticles by sedimentation velocity

    KAUST Repository

    Demeler, Borries

    2014-08-05

    A critical problem in materials science is the accurate characterization of the size dependent properties of colloidal inorganic nanocrystals. Due to the intrinsic polydispersity present during synthesis, dispersions of such materials exhibit simultaneous heterogeneity in density ρ, molar mass M, and particle diameter d. The density increments ∂ρ/∂d and ∂ρ/∂M of these nanoparticles, if known, can then provide important information about crystal growth and particle size distributions. For most classes of nanocrystals, a mixture of surfactants is added during synthesis to control their shape, size, and optical properties. However, it remains a challenge to accurately determine the amount of passivating ligand bound to the particle surface post synthesis. The presence of the ligand shell hampers an accurate determination of the nanocrystal diameter. Using CdSe and PbS semiconductor nanocrystals, and the ultrastable silver nanoparticle (M4Ag 44(p-MBA)30), as model systems, we describe a Custom Grid method implemented in UltraScan-III for the characterization of nanoparticles and macromolecules using sedimentation velocity analytical ultracentrifugation. We show that multiple parametrizations are possible, and that the Custom Grid method can be generalized to provide high resolution composition information for mixtures of solutes that are heterogeneous in two out of three parameters. For such cases, our method can simultaneously resolve arbitrary two-dimensional distributions of hydrodynamic parameters when a third property can be held constant. For example, this method extracts partial specific volume and molar mass from sedimentation velocity data for cases where the anisotropy can be held constant, or provides anisotropy and partial specific volume if the molar mass is known. © 2014 American Chemical Society.

  1. Mixing properties of coaxial jets with large velocity ratios and large inverse density ratios

    Science.gov (United States)

    Alexander Schumaker, S.; Driscoll, James F.

    2012-05-01

    An experimental study was conducted to better understand the mixing properties of coaxial jets as several parameters were systematically varied, including the velocity ratio, density ratio, and the Reynolds number. Diameters of the inner and outer jet were also varied. Coaxial jets are commonly used to mix fluids due to the simplicity of their geometry and the rapid mixing that they provide. A measure of the overall mixing efficiency is the stoichiometric mixing length (Ls), which is the distance along the jet centerline where the two fluids have mixed to some desired concentration, which was selected to be the stoichiometric concentration for H2/O2 and CH4/O2 in this case. For 56 cases, the profiles of mean mixture fraction, rms mixture fraction fluctuations (unmixedness), and Ls were measured using acetone planar laser induced fluorescence diagnostics. Results were compared to three mixing models. The entrainment model of Villermaux and Rehab showed good agreement with the data, indicating that the proper non-dimensional scaling parameter is the momentum flux ratio M. The work extends the existing database of coaxial jet scalar mixing properties because it considers the specific regime of large values of both the velocity ratio and the inverse density ratio, which is the regime in which rocket injectors operate. Also the work focuses on the mixing up to Ls where previous work focused on the mixing up to the end of the inner core. The Reynolds numbers achieved for a number of cases were considerably larger than previous gas mixing studies, which insures that the jet exit boundary conditions are fully turbulent.

  2. Comparison of three velocity measurement systems - A laser transit anemometer (LTA), an on axis laser Doppler anemometer (LDA) and a constant temperature hot-wire anemometer (CTA)

    Science.gov (United States)

    Bennett, M. J.; Mawlood, S. N.; Al-Daini, A. J.; Girgis, N. S.

    Three flow-velocity measurement systems, an on-axis LDA, an LTA, and a constant temperature hot-wire anemometer (CTA), are described and compared by applying them to the measurement of velocity in a high-pressure closed-circuit wind tunnel and to the velocity profiles of a free jet. A system operating on the LTA principle, the Polytec L2F, was used to produce the probability density functions for the two flow situations and to calibrate the hot-wire CTA system, and the hot-wire calibration curve at normal pressure and temperature was used to develop a semiempirical model for the evaluation of velocity at elevated pressures and temperatures. An experimental arrangement in which LTA and LDA measuring systems may be used simultaneously with no separation of the respective measuring volumes in any axis is described, and the methods which may be used to counteract the inaccuracies of such an arrangement are discussed.

  3. Use of the Hot Wire Anemometry for Velocity and Temperature Measurements in a Turbomachine

    OpenAIRE

    Blidi, Sami; Miton, Hubert

    1995-01-01

    The hot film anemometry in a highly heterogeneous unsteady flow is a quite complex measurement technique. The velocity is determined from the heat flux measurement. The part of the signal related to velocity must be kept apart from one related to temperature and to pressure of flow. After a brief return to the principle of hot wire anemometry and the different heat transfer models between hot wire and flow, an experimentally established heat flux expression is presented. This study was achiev...

  4. Exact conditions on the temperature dependence of density functionals

    CERN Document Server

    Burke, Kieron; Grabowski, Paul E; Pribram-Jones, Aurora

    2015-01-01

    Universal exact conditions guided the construction of most ground-state density functional approximations in use today. We derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

  5. Exact conditions on the temperature dependence of density functionals

    Science.gov (United States)

    Burke, K.; Smith, J. C.; Grabowski, P. E.; Pribram-Jones, A.

    2016-05-01

    Universal exact conditions guided the construction of most ground-state density functional approximations in use today. We derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

  6. Thermoelastic properties of liquid Fe-C revealed by sound velocity and density measurements at high pressure

    Science.gov (United States)

    Shimoyama, Yuta; Terasaki, Hidenori; Urakawa, Satoru; Takubo, Yusaku; Kuwabara, Soma; Kishimoto, Shunpachi; Watanuki, Tetsu; Machida, Akihiko; Katayama, Yoshinori; Kondo, Tadashi

    2016-11-01

    Carbon is one of the possible light elements in the cores of the terrestrial planets. The P wave velocity (VP) and density (ρ) are important factors for estimating the chemical composition and physical properties of the core. We simultaneously measured the VP and ρ of Fe-3.5 wt % C up to 3.4 GPa and 1850 K by using ultrasonic pulse-echo method and X-ray absorption methods. The VP of liquid Fe-3.5 wt % C decreased linearly with increasing temperature at constant pressure. The addition of carbon decreased the VP of liquid Fe by about 2% at 3 GPa and 1700 K and decreased the Fe density by about 2% at 2 GPa and 1700 K. The bulk modulus of liquid Fe-C and its pressure (P) and temperature (T) effects were precisely determined from directly measured ρ and VP data to be K0,1700 K = 83.9 GPa, dKT/dP = 5.9(2), and dKT/dT = -0.063 GPa/K. The addition of carbon did not affect the isothermal bulk modulus (KT) of liquid Fe, but it decreased the dK/dT of liquid Fe. In the ρ-VP relationship, VP increases linearly with ρ and can be approximated as VP (m/s) = -6786(506) + 1537(71) × ρ (g/cm3), suggesting that Birch's law is valid for liquid Fe-C at the present P-T conditions. Our results imply that at the conditions of the lunar core, the elastic properties of an Fe-C core are more affected by temperature than those of Fe-S core.

  7. Density of states and dynamical crossover in a dense fluid revealed by exponential mode analysis of the velocity autocorrelation function

    Science.gov (United States)

    Bellissima, S.; Neumann, M.; Guarini, E.; Bafile, U.; Barocchi, F.

    2017-01-01

    Extending a preceding study of the velocity autocorrelation function (VAF) in a simulated Lennard-Jones fluid [Phys. Rev. E 92, 042166 (2015), 10.1103/PhysRevE.92.042166] to cover higher-density and lower-temperature states, we show that the recently demonstrated multiexponential expansion method allows for a full account and understanding of the basic dynamical processes encompassed by a fundamental quantity as the VAF. In particular, besides obtaining evidence of a persisting long-time tail, we assign specific and unambiguous physical meanings to groups of exponential modes related to the longitudinal and transverse collective dynamics, respectively. We have made this possible by consistently introducing the interpretation of the VAF frequency spectrum as a global density of states in fluids, generalizing a solid-state concept, and by giving to specific spectral components, obtained through the VAF exponential expansion, the corresponding meaning of partial densities of states relative to specific dynamical processes. The clear identification of a high-frequency oscillation of the VAF with the near-top excitation frequency in the dispersion curve of acoustic waves is a neat example of the power of the method. As for the transverse mode contribution, its analysis turns out to be particularly important, because the multiexponential expansion reveals a transition marking the onset of propagating excitations when the density is increased beyond a threshold value. While this finding agrees with the recent literature debating the issue of dynamical crossover boundaries, such as the one identified with the Frenkel line, we can add detailed information on the modes involved in this specific process in the domains of both time and frequency. This will help obtain a still missing full account of transverse dynamics, in both its nonpropagating and propagating aspects which are linked through dynamical transitions depending on both the thermodynamic states and the excitation

  8. Friedberg-Lee model at finite temperature and density

    Science.gov (United States)

    Mao, Hong; Yao, Minjie; Zhao, Wei-Qin

    2008-06-01

    The Friedberg-Lee model is studied at finite temperature and density. By using the finite temperature field theory, the effective potential of the Friedberg-Lee model and the bag constant B(T) and B(T,μ) have been calculated at different temperatures and densities. It is shown that there is a critical temperature TC≃106.6 MeV when μ=0 MeV and a critical chemical potential μ≃223.1 MeV for fixing the temperature at T=50 MeV. We also calculate the soliton solutions of the Friedberg-Lee model at finite temperature and density. It turns out that when T⩽TC (or μ⩽μC), there is a bag constant B(T) [or B(T,μ)] and the soliton solutions are stable. However, when T>TC (or μ>μC) the bag constant B(T)=0 MeV [or B(T,μ)=0 MeV] and there is no soliton solution anymore, therefore, the confinement of quarks disappears quickly.

  9. The Friedberg-Lee model at finite temperature and density

    CERN Document Server

    Mao, Hong; Zhao, Wei-Qin

    2007-01-01

    The Friedberg-Lee model is studied at finite temperature and density. By using the finite temperature field theory, the effective potential of the Friedberg-Lee model and the bag constant $B(T)$ and $B(T,\\mu)$ have been calculated at different temperatures and densities. It is shown that there is a critical temperature $T_{C}\\simeq 106.6 \\mathrm{MeV}$ when $\\mu=0 \\mathrm{MeV}$ and a critical chemical potential $\\mu \\simeq 223.1 \\mathrm{MeV}$ for fixing the temperature at $T=50 \\mathrm{MeV}$. We also calculate the soliton solutions of the Friedberg-Lee model at finite temperature and density. It turns out that when $T\\leq T_{C}$ (or $\\mu \\leq \\mu_C$), there is a bag constant $B(T)$ (or $B(T,\\mu)$) and the soliton solutions are stable. However, when $T>T_{C}$ (or $\\mu>\\mu_C$) the bag constant $B(T)=0 \\mathrm{MeV}$ (or $B(T,\\mu)=0 \\mathrm{MeV}$) and there is no soliton solution anymore, therefore, the confinement of quarks disappears quickly.

  10. Millennial-scale temperature change velocity in the continental northern Neotropics.

    Science.gov (United States)

    Correa-Metrio, Alexander; Bush, Mark; Lozano-García, Socorro; Sosa-Nájera, Susana

    2013-01-01

    Climate has been inherently linked to global diversity patterns, and yet no empirical data are available to put modern climate change into a millennial-scale context. High tropical species diversity has been linked to slow rates of climate change during the Quaternary, an assumption that lacks an empirical foundation. Thus, there is the need for quantifying the velocity at which the bioclimatic space changed during the Quaternary in the tropics. Here we present rates of climate change for the late Pleistocene and Holocene from Mexico and Guatemala. An extensive modern pollen survey and fossil pollen data from two long sedimentary records (30,000 and 86,000 years for highlands and lowlands, respectively) were used to estimate past temperatures. Derived temperature profiles show a parallel long-term trend and a similar cooling during the Last Glacial Maximum in the Guatemalan lowlands and the Mexican highlands. Temperature estimates and digital elevation models were used to calculate the velocity of isotherm displacement (temperature change velocity) for the time period contained in each record. Our analyses showed that temperature change velocities in Mesoamerica during the late Quaternary were at least four times slower than values reported for the last 50 years, but also at least twice as fast as those obtained from recent models. Our data demonstrate that, given extremely high temperature change velocities, species survival must have relied on either microrefugial populations or persistence of suppressed individuals. Contrary to the usual expectation of stable climates being associated with high diversity, our results suggest that Quaternary tropical diversity was probably maintained by centennial-scale oscillatory climatic variability that forestalled competitive exclusion. As humans have simplified modern landscapes, thereby removing potential microrefugia, and climate change is occurring monotonically at a very high velocity, extinction risk for tropical

  11. Millennial-scale temperature change velocity in the continental northern Neotropics.

    Directory of Open Access Journals (Sweden)

    Alexander Correa-Metrio

    Full Text Available Climate has been inherently linked to global diversity patterns, and yet no empirical data are available to put modern climate change into a millennial-scale context. High tropical species diversity has been linked to slow rates of climate change during the Quaternary, an assumption that lacks an empirical foundation. Thus, there is the need for quantifying the velocity at which the bioclimatic space changed during the Quaternary in the tropics. Here we present rates of climate change for the late Pleistocene and Holocene from Mexico and Guatemala. An extensive modern pollen survey and fossil pollen data from two long sedimentary records (30,000 and 86,000 years for highlands and lowlands, respectively were used to estimate past temperatures. Derived temperature profiles show a parallel long-term trend and a similar cooling during the Last Glacial Maximum in the Guatemalan lowlands and the Mexican highlands. Temperature estimates and digital elevation models were used to calculate the velocity of isotherm displacement (temperature change velocity for the time period contained in each record. Our analyses showed that temperature change velocities in Mesoamerica during the late Quaternary were at least four times slower than values reported for the last 50 years, but also at least twice as fast as those obtained from recent models. Our data demonstrate that, given extremely high temperature change velocities, species survival must have relied on either microrefugial populations or persistence of suppressed individuals. Contrary to the usual expectation of stable climates being associated with high diversity, our results suggest that Quaternary tropical diversity was probably maintained by centennial-scale oscillatory climatic variability that forestalled competitive exclusion. As humans have simplified modern landscapes, thereby removing potential microrefugia, and climate change is occurring monotonically at a very high velocity, extinction risk

  12. Molecular hydrogen emission as a density and temperature indicator

    Science.gov (United States)

    Wang, Xiang; Ferland, Gary J.; Baldwin, Jack A.; Loh, Edwin D.; Fabian, Andy C.; Williams, Robin

    2016-01-01

    Infrared observations have discovered a variety of objects, including filaments in the Crab Nebula and cool-core clusters of galaxies, where the 1-0 S(1) line is stronger than the infrared H I lines. A variety of processes could be responsible for this emission. Although many complete shock or PDR calculations of emission have been published, we know of no previous simple calculation that shows the emission spectrum and level populations of thermally excited low-density . We present a range of purely thermal collisional simulations, corresponding to constant gas kinetic temperature at different densities. We consider the cases where the collisions affecting H2 are predominantly with atomic or molecular hydrogen. The resulting level population (often called "excitation") diagrams show that excitation temperatures are sometimes lower than the gas kinetic temperature when the density is too low for the level populations to go to LTE. The atomic case goes to LTE at much lower densities than the molecular case due to larger collision rates. At low densities for the v=1 and 2 vibrational manifolds level populations are quasi-thermal, which could be misinterpreted as showing the gas is in LTE at high density. At low densities for the molecular case the level population diagrams are discontinuous between v=0 and 1 vibrational manifolds and between v=2, J=0, 1 and other higher J levels within the same vibrational manifold. These jumps could be used as density diagnostics. We show how much the H2 mass would be underestimated using the 1-0 S(1) line strength if the density is below that required for LTE. We give diagnostic diagrams showing level populations over a range of density and temperature. The density where the level populations are given by a Boltzmann distribution relative to the total molecular abundance (required to get the correct H2 mass), is shown for various cases. We discuss the implications of these results for the interpretation of H2 observations of the

  13. Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures.

    Science.gov (United States)

    Shen, Chen; Julius, Ethan F; Tyree, Timothy J; Dan, Ritwik; Moreau, David W; Thorne, Robert

    2017-06-28

    We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid cooling, to prepare the desired cryogenic temperature phase. Microliter to picoliter size drops are cooled by projection into a liquid nitrogen-argon (N2-Ar) mixture. The cryogenic temperature phase of the drop is evaluated using a visual assay that correlates with X-ray diffraction measurements. The density of the liquid N2-Ar mixture is adjusted by adding N2 or Ar until the drop becomes neutrally buoyant. The density of this mixture and thus of the drop is determined using a test mass and Archimedes principle. With appropriate care in drop preparation, management of gas above the liquid cryogen mixture to minimize icing, and regular mixing of the cryogenic mixture to prevent density stratification and phase separation, densities accurate to <0.5% of drops as small as 50 pL can readily be determined. Measurements on aqueous cryoprotectant mixtures provide insight into cryoprotectant action, and provide quantitative data to facilitate thermal contraction matching in biological cryopreservation.

  14. Temperature and Density Measurements in a Quiet Coronal Streamer

    Science.gov (United States)

    Warren, Harry P.; Warshall, Andrew D.

    2002-06-01

    Many previous studies have used emission line or broadband filter ratios to infer the presence of temperature gradients in the quiet solar corona. Recently it has been suggested that these temperature gradients are not real, but result from the superposition of isothermal loops with different temperatures and density scale heights along the line of sight. A model describing this hydrostatic weighting bias has been developed by Aschwanden & Acton. In this paper we present the application of the Aschwanden & Acton differential emission measure model to Solar and Heliospheric Observatory Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a quiet coronal streamer. Simultaneous Yohkoh soft X-ray telescope (SXT) observations show increases in the filter ratios with height above the limb, indicating an increase in temperature. The application of the Aschwanden & Acton model to these SUMER data, however, show that the temperature is constant with height and that the distribution of temperatures in the corona is much too narrow for the hydrostatic weighting bias to have any effect on the SXT filter ratios. We consider the possibility that there is a tenuous hot component (~3 MK) that accounts for the SXT observations. We find that a hot plasma with an emission measure sufficient to reproduce the observed SXT fluxes would also produce significant count rates in the high-temperature emission lines in the SUMER wavelength range. These lines are not observed, and we conclude that the SUMER spectra are not consistent with the SXT filter ratio temperatures. Calculations from a hydrodynamic loop model suggest that nonuniform footpoint heating may be consistent with the temperatures and densities observed at most heights, consistent with the recent analysis of relatively cool (~1 MK) active region loops. We also find, however, that at the lowest heights the observed densities are smaller than those predicted by uniform or footpoint heating.

  15. Lattice QCD Results at Finite Temperature and Density

    CERN Document Server

    Fodor, Z

    2003-01-01

    Recent lattice results on QCD at finite temperatures and densities are reviewed. Two new and independent techniques give compatible results for physical quantities. The phase line separating the hadronic and quark-gluon plasma phases, the critical endpoint and the equation of state are discussed.

  16. Statistics of velocity and temperature fluctuations in two-dimensional Rayleigh-Bénard convection

    Science.gov (United States)

    Zhang, Yang; Huang, Yong-Xiang; Jiang, Nan; Liu, Yu-Lu; Lu, Zhi-Ming; Qiu, Xiang; Zhou, Quan

    2017-08-01

    We investigate fluctuations of the velocity and temperature fields in two-dimensional (2D) Rayleigh-Bénard (RB) convection by means of direct numerical simulations (DNS) over the Rayleigh number range 106≤Ra≤1010 and for a fixed Prandtl number Pr=5.3 and aspect ratio Γ =1 . Our results show that there exists a counter-gradient turbulent transport of energy from fluctuations to the mean flow both locally and globally, implying that the Reynolds stress is one of the driving mechanisms of the large-scale circulation in 2D turbulent RB convection besides the buoyancy of thermal plumes. We also find that the viscous boundary layer (BL) thicknesses near the horizontal conducting plates and near the vertical sidewalls, δu and δv, are almost the same for a given Ra, and they scale with the Rayleigh and Reynolds numbers as ˜Ra-0.26±0.03 and ˜Re-0.43±0.04 . Furthermore, the thermal BL thickness δθ defined based on the root-mean-square (rms) temperature profiles is found to agree with Prandtl-Blasius predictions from the scaling point of view. In addition, the probability density functions of turbulent energy ɛu' and thermal ɛθ' dissipation rates, calculated, respectively, within the viscous and thermal BLs, are found to be always non-log-normal and obey approximately a Bramwell-Holdsworth-Pinton distribution first introduced to characterize rare fluctuations in a confined turbulent flow and critical phenomena.

  17. Influence of temperature on the spreading velocity of simplified-step adhesive systems.

    Science.gov (United States)

    Pazinatto, Flávia Bittencourt; Marquezini, Luiz; Atta, Maria Teresa

    2006-01-01

    Flowability and viscosity vary for different adhesive systems owing to differences in their composition. These characteristics can be modified by environmental temperature. The purpose of this study was to determine the influence of temperature on the spreading (flow capacity) of simplified-step adhesive systems. Spreading velocities of adhesive systems (Adper Single Bond and Single Bond Plus [3M ESPE, St. Paul, MN, USA]; Prime & Bond 2.1 and Prime & Bond NT [Dentsply Indústria e Comércio Ltda, Petrópolis, RJ, Brazil]; Adper Prompt [3M ESPE]; and One Up Bond F [Tokuyama Corp, Tokyo, Japan]) were analyzed at intervals of 10, 15, 20, and 30 seconds at both 25 degrees C and 37 degrees C by placing 10 microL drops on a glass slide surface with an inclination of 45 degrees. The spreading of each adhesive system was measured in millimeters per second. Data were analyzed by two-way analysis of variance and Student-Newman-Keuls tests. Regression analysis was used to determine a correlation between spreading velocity and time. Statistical significance was considered at a confidence level of 95%. Temperature influenced the spreading velocity, increasing it for Single Bond and Prime & Bond 2.1 and decreasing it for Adper Prompt (p adhesives studied (p >.05). Regression analysis of each adhesive system demonstrated an inverse correlation between mean spreading velocity and time (R2 = .999) on both temperatures. Temperature increases yielded an increase of spreading for Single Bond and Prime & Bond 2.1. The influence of temperature on the spreading velocity was material dependent. Environmental temperature can influence the rate of spreading of the adhesive system in clinically relevant times and may influence adhesive thickness on cavity walls.

  18. Luminescent two-color tracer particles for simultaneous velocity and temperature measurements in microfluidics

    Science.gov (United States)

    Massing, J.; Kaden, D.; Kähler, C. J.; Cierpka, C.

    2016-11-01

    The simultaneous and non-intrusive measurement of temperature and velocity fields in flows is of great scientific and technological interest. To sample the velocity and temperature, tracer particle based approaches have been developed, where the velocity is measured using PIV or PTV and the temperature is obtained from the intensity (LIF, thermographic phosphors) or frequency (TLC) of the light emitted or reflected by the tracer particles. In this article, a measurement technique is introduced, that relates the luminescent intensity ratio of individual dual-color luminescent tracer particles to temperature. Different processing algorithms are tested on synthetic particle images and compared with respect to their accuracy in estimating the intensity ratio. Furthermore, polymer particles which are doped with the temperature sensitive dye europium (III) thenoyltrifluoroacetonate (EuTTA) and the nearly temperature insensitive reference dye perylene are characterized as valid tracers. The results show a reduction of the temperature measurement uncertainty of almost 40% (95% confidence interval) compared to previously reported luminescent particle based measurement techniques for microfluidics.

  19. An exospheric temperature model from CHAMP thermospheric density

    Science.gov (United States)

    Weng, Libin; Lei, Jiuhou; Sutton, Eric; Dou, Xiankang; Fang, Hanxian

    2017-02-01

    In this study, the effective exospheric temperature, named as T∞, derived from thermospheric densities measured by the CHAMP satellite during 2002-2010 was utilized to develop an exospheric temperature model (ETM) with the aid of the NRLMSISE-00 model. In the ETM, the temperature variations are characterized as a function of latitude, local time, season, and solar and geomagnetic activities. The ETM is validated by the independent GRACE measurements, and it is found that T∞ and thermospheric densities from the ETM are in better agreement with the GRACE data than those from the NRLMSISE-00 model. In addition, the ETM captures well the thermospheric equatorial anomaly feature, seasonal variation, and the hemispheric asymmetry in the thermosphere.

  20. Temperature and velocity fields in natural convection by PIV and LIF

    DEFF Research Database (Denmark)

    Meyer, Knud Erik; Larsen, Poul Scheel; Westergaard, C. H.

    2002-01-01

    plate and cooled walls is 1.4×10^10. The flow is turbulent and is similar to some indoor room flows. Combined Particle Image Velocimetry (PIV) and Planar Light Induced Fluorescence (LIF) are used to measure local velocities and temperatures. Data measured in a symmetry plane parallel to a sidewall......Natural convection in a cubical cavity (L = 250 mm) filled with water is created by heating a square plate (0.5 L) centred in the bottom wall and by cooling the sidewalls, while the remaining walls are insulated. The Rayleigh number based on cavity side length and temperature difference between...... are presented in terms of mean velocities and temperature and in terms turbulent quantities including Reynolds fluxes. The flow consists a plume rising above the heated plate into an almost stagnant fluid with a weakly stratified temperature field, as well as thin buoyancy driven boundary layers down...

  1. Temperature Control of Heating Zone for Drying Process: Effect of Air Velocity Change

    Directory of Open Access Journals (Sweden)

    Wutthithanyawat Chananchai

    2016-01-01

    Full Text Available This paper proposes a temperature control technique to adjust air temperature in a heating zone for drying process. The controller design is achieved by using an internal model control (IMC approach. When the IMC controller parameters were designed by calculating from an actual process transfer function estimated through an open-loop step response with input step change from 50% to 60% at a reference condition at air velocity of 1.20 m/s, the performance of temperature controller was experimentally tested by varying an air velocity between 1.32 m/s and 1.57 m/s, respectively. The experimental results showed that IMC controller had a high competency for controlling the drying temperature.

  2. Velocity measurement in life combustion systems with high temperature anemometer - HTA

    Energy Technology Data Exchange (ETDEWEB)

    Staudinger, G.; Mory, A.; Pilz, R.; Zimmel, M. [Technische Universitaet Graz, Graz (Austria). Inst. fuer Verfahrenstechnik, Abt. fuer Apparatebau und Mechanische Verfahrenstechnik

    1998-12-31

    An anemometer was developed which allows to measure velocities in dusty atmospheres at temperatures up to 1200{degree}C in a range between 1 and 40 m/s. The most important features of this vane-anemometer are its frictionless aerostatic bearing and the internal air cooling. The frequency of rotation is detected with a high temperature resistant optical fibre. In the project velocities and velocity-fields were measured in the combustion chambers of a 300 MW{sub el} power plant, a 27 MW{sub th} waste incinerator and in different pilot- and semi-industrial plants. The fuels used were coal, biomass, and municipal waste. 11 figs., 2 tabs.

  3. Sound velocity and temperature data from sound velocity strip charts and XBT casts from the USS PORTER from 28 August 2000 to 22 October 2000 (NODC Accession 0000343)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sound velocity and temperature data were collected from the USS PORTER from August 28, 2000 to October 22, 2000. Data were submitted by the US NAVY; Ships of...

  4. Design and construction of a low-velocity boundary-layer temperature probe

    Science.gov (United States)

    Blackwell, B. F.; Moffat, R. J.

    1974-01-01

    This paper presents the results of a study performed to determine the probe geometry and thermal characteristics for a low-velocity boundary-layer temperature probe capable of eliminating conduction errors. Design curves for four common thermoelectric pairs are presented, and an experimental turbulent boundary-layer temperature profile is compared with the theoretical laminar sublayer equation to verify that the probe eliminates conduction errors.

  5. A zero-gravity instrument to study low velocity collisions of fragile particles at low temperatures

    NARCIS (Netherlands)

    Salter, D. M.; Heisselmann, D.; Chaparro, G.; van der Wolk, G.; Reissaus, P.; Borst, A. G.; Dawson, R. W.; de Kuyper, E.; Drinkwater, G.; Gebauer, K.; Hutcheon, M.; Linnartz, H.; Molster, F. J.; Stoll, B.; van der Tuijn, P. C.; Fraser, H. J.; Blum, J.

    2009-01-01

    We discuss the design, operation, and performance of a vacuum setup constructed for use in zero (or reduced) gravity conditions to initiate collisions of fragile millimeter-sized particles at low velocity and temperature. Such particles are typically found in many astronomical settings and in region

  6. Measurement of Plasma Ion Temperature and Flow Velocity from Chord-Averaged Emission Line Profile

    Indian Academy of Sciences (India)

    Xu Wei

    2011-03-01

    The distinction between Doppler broadening and Doppler shift has been analysed, the differences between Gaussian fitting and the distribution of chord-integral line shape have also been discussed. Local ion temperature and flow velocity have been derived from the chord-averaged emission line profile by a chosen-point Gaussian fitting technique.

  7. Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

    DEFF Research Database (Denmark)

    Olsen, Jeppe Miki Busk; Madsen, Jens; Nielsen, Anders Henry

    2016-01-01

    The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocit...

  8. Temperature and temporal dependence of neutral density transmittance standards

    Science.gov (United States)

    Koo, A.; Hamlin, J. D.

    2012-04-01

    The Schott series of NG glasses are frequently used to manufacture neutral density transmittance standards for validation of spectrophotometer systems as well as for comparisons of regular spectral transmittance scales. A study has been made of the temperature and temporal dependence of transmittance in these types of filters. The temperature dependence of transmittance is found to scale as -ln(T). The filter transmittance was found to vary significantly with time shortly after manufacture but appears to be stabilizing nine months after beginning measurements.

  9. Dependence of ion drift velocity and diffusion coefficient in parent gas on its temperature

    Science.gov (United States)

    Maiorov, Sergey; Golyatina, Rusudan

    2016-09-01

    The results of Monte Carlo calculations of the ion drift characteristics are presented: ions of noble gases and Ti, Fe, Co, Cs, Rb, W and mercury ions in case of constant and uniform electric field are considered. The dependences of the ion mobility on the field strength and gas temperature are analyzed. The parameters of the drift velocity approximation by the Frost formula for gas temperatures of 4.2, 77, 300, 1000, and 2000 K are presented. A universal drift velocity approximation depending on the reduced electric field strength and gas temperature is obtained. In the case of strong electric fields or low gas temperatures, the deviation of the ion distribution function from the Maxwellian one (including the shifted Maxwellian one) can be very significant. The average energies of chaotic motion of ions along and across the electric field can also differ significantly. It is analyzed the kinetic characteristics of ion drift in own gas: ion diffusion coefficient along the field and across the field; thermal spread of velocities (temperature) along the field and across the field. The unexpected and nontrivial fact takes place: collision with backscattering represent only 10-50% of the total number of collisions. This calculation can be used when analyzing experiments with dusty plasma under cryogenic discharge, ultracold plasma. The work was supported by the Russian Science Foundation (grant RNF 14-19-01492).

  10. Control of high velocity lithosphere roots on crustal scale density variations seen in Gondwana reconstructions

    Science.gov (United States)

    Braitenberg, C. F.; Mariani, P.

    2015-12-01

    The GOCE gravity field is globally homogeneous at the resolution of about 80km or better allowing for the first time to identify tectonic structures at continental scale. The large scale structures are presumably controlled by the rheology of the underlying crust down to the base of the lithosphere. Seismic tomography identifies the presence of the deep lithosphere roots by increased velocity. The joint analysis of the tomography results and the GOCE gravity reveals that at global scale the two data have some common patterns. The correlations are enhanced by applying geodynamic plate reconstructions to the GOCE gravity field and to the tomography models which places today's observed fields at the Gondwana pre-breakup position. There are several examples for which it is found that the deep lithospheric roots, as those found below cratons, control the position of the positive gravity values outboard of the deep roots. This could be explained by the deep lithospheric roots focusing asthenospheric upwelling outboard of the root protecting the overlying craton from magmatic intrusions. Over several of the deep roots the gravity is systematically negative, which could be due to a compositional effect, with deep roots of increased velocity having reduced density. The study is carried out globally, with focus on the African and South American continents. The background for the study can be found in the following publications where the techniques which have been used are described: Braitenberg, C., Mariani, P. and De Min, A. (2013). The European Alps and nearby orogenic belts sensed by GOCE, Boll. Bollettino di Geofisica Teorica ed Applicata, 54(4), 321-334. doi:10.4430/bgta0105 Braitenberg, C. and Mariani, P. (2015). Geological implications from complete Gondwana GOCE-products reconstructions and link to lithospheric roots. Proceedings of 5th International GOCE User Workshop, 25 - 28 November 2014. Braitenberg, C. (2015). Exploration of tectonic structures with GOCE in

  11. Charge, density and electron temperature in a molecular ultracold plasma

    CERN Document Server

    Rennick, C J; Ortega-Arroyo, J; Godin, P J; Grant, E R

    2009-01-01

    A Rydberg gas of NO entrained in a supersonic molecular beam releases electrons as it evolves to form an ultracold plasma. The size of this signal, compared with that extracted by the subsequent application of a pulsed electric field, determines the absolute magnitude of the plasma charge. This information, combined with the number density of ions, supports a simple thermochemical model that explains the evolution of the plasma to an ultracold electron temperature.

  12. Temperature and density effects on the nucleon mass splitting

    CERN Document Server

    Christiansen, H R; Fanchiotti, H; Garc, C A

    1996-01-01

    The finite temperature and finite density dependence of the neu\\-tron-proton mass difference is analysed in a purely hadronic framework where the \\rho-\\omega mixing is crucial for this isospin symmetry breakdown. The problem is handled within Thermo Field Dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei.

  13. Temperature and density effects on the nucleon mass splitting

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, H.R.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A. [Departamento de Fisica, Universidad Nacional de La Plata C.C. 67, (1900) La Plata (Argentina)

    1996-04-01

    The finite temperature and finite density dependence of the neutron-proton mass difference is analyzed in a purely hadronic framework where the {rho}-{omega} mixing is crucial for this isospin symmetry breakdown. The problem is handled within thermofield dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei. {copyright} {ital 1996 The American Physical Society.}

  14. Reduced density matrix functional theory at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Baldsiefen, Tim

    2012-10-15

    Density functional theory (DFT) is highly successful in many fields of research. There are, however, areas in which its performance is rather limited. An important example is the description of thermodynamical variables of a quantum system in thermodynamical equilibrium. Although the finite-temperature version of DFT (FT-DFT) rests on a firm theoretical basis and is only one year younger than its brother, groundstate DFT, it has been successfully applied to only a few problems. Because FT-DFT, like DFT, is in principle exact, these shortcomings can be attributed to the difficulties of deriving valuable functionals for FT-DFT. In this thesis, we are going to present an alternative theoretical description of quantum systems in thermal equilibrium. It is based on the 1-reduced density matrix (1RDM) of the system, rather than on its density and will rather cumbersomly be called finite-temperature reduced density matrix functional theory (FT-RDMFT). Its zero-temperature counterpart (RDMFT) proved to be successful in several fields, formerly difficult to address via DFT. These fields include, for example, the calculation of dissociation energies or the calculation of the fundamental gap, also for Mott insulators. This success is mainly due to the fact that the 1RDM carries more directly accessible ''manybody'' information than the density alone, leading for example to an exact description of the kinetic energy functional. This sparks the hope that a description of thermodynamical systems employing the 1RDM via FT-RDMFT can yield an improvement over FT-DFT. Giving a short review of RDMFT and pointing out difficulties when describing spin-polarized systems initiates our work. We then lay the theoretical framework for FT-RDMFT by proving the required Hohenberg-Kohn-like theorems, investigating and determining the domain of FT-RDMFT functionals and by deriving several properties of the exact functional. Subsequently, we present a perturbative method to

  15. The spatial and velocity bias of linear density peaks and proto-haloes in the LCDM cosmology

    CERN Document Server

    Elia, Anna; Porciani, Cristiano

    2011-01-01

    We use high resolution N-body simulations to investigate the Lagrangian bias of cold dark matter haloes within the LCDM cosmology. Our analysis focuses on "proto-haloes", which we identify in the simulation initial conditions with the subsets of particles belonging to individual redshift-zero haloes. We then calculate the number-density and velocity-divergence fields of proto-haloes and estimate their auto spectral densities. We also measure the corresponding cross spectral densities with the linear matter distribution. We use our results to test a Lagrangian-bias model presented by Desjacques and Sheth which is based on the assumption that haloes form out of local density maxima of a specific height. Our comparison validates the predicted functional form for the scale-dependence of the bias for both the density and velocity fields. We also show that the bias coefficients are accurately predicted for the velocity divergence. On the contrary, the theoretical values for the density bias parameters do not accura...

  16. Determination of the integral characteristics of an asymmetrical thermal plume from air speed/velocity and temperature measurements

    DEFF Research Database (Denmark)

    Zukowska, Daria; Popiolek, Zbigniew; Melikov, Arsen Krikor

    2010-01-01

    A method, named the Approximate Distributions Integration Method (ADI-method), is proposed for calculation of parameters of the asymmetrical thermal plume above a heat source, such as maximum air temperature excess and velocity, their position in the plume cross-section, the widths...... of the temperature and velocity profiles, asymmetry parameters of the plume cross-section, and the integral characteristics. The method is based on an approximation of the measured profiles of air velocity and air temperature excess in the plume cross-section. A procedure for conversion of the air speed measured...... by omnidirectional sensors into air velocity is incorporated with the ADI-method. Experiments were performed in a climate chamber with air temperature of 23 _C, radiant temperature equal to the air temperature and upward airflow with velocity of less than 0.05 m/s. Air speed and temperature in a thermal plume...

  17. The relation between gas density and velocity power spectra in galaxy clusters: qualitative treatment and cosmological simulations

    CERN Document Server

    Zhuravleva, I; Schekochihin, A A; Lau, E T; Nagai, D; Gaspari, M; Allen, S W; Nelson, K; Parrish, I J

    2014-01-01

    We address the problem of evaluating the power spectrum of the velocity field of the ICM using only information on the plasma density fluctuations, which can be measured today by Chandra and XMM-Newton observatories. We argue that for relaxed clusters there is a linear relation between the rms density and velocity fluctuations across a range of scales, from the largest ones, where motions are dominated by buoyancy, down to small, turbulent scales: $(\\delta\\rho_k/\\rho)^2 = \\eta_1^2 (V_{1,k}/c_s)^2$, where $\\delta\\rho_k/\\rho$ is the spectral amplitude of the density perturbations at wave number $k$, $V_{1,k}^2=V_k^2/3$ is the mean square component of the velocity field, $c_s$ is the sound speed, and $\\eta_1$ is a dimensionless constant of order unity. Using cosmological simulations of relaxed galaxy clusters, we calibrate this relation and find $\\eta_1\\approx 1 \\pm 0.3$. We argue that this value is set at large scales by buoyancy physics, while at small scales the density and velocity power spectra are proporti...

  18. Laboratory observations of velocity and density fields in the entrance of a harbor on a stratified tidal river

    NARCIS (Netherlands)

    Langendoen, E.J.; Karelse, M.

    1990-01-01

    Detailed measurements are presented of velocity and density fields in the entrance of a model harbor on a stratified tidal river. Three geometries of the harbor entrance were examined, (1) a harbor with its length axis perpendicular to the river and an entrance width of 1 m, (2) as (1) but with an

  19. Density and P-wave velocity structure beneath the Paraná Magmatic Province: Refertilization of an ancient lithospheric mantle

    Science.gov (United States)

    Chaves, Carlos; Ussami, Naomi; Ritsema, Jeroen

    2016-08-01

    We estimate density and P-wave velocity perturbations in the mantle beneath the southeastern South America plate from geoid anomalies and P-wave traveltime residuals to constrain the structure of the lithosphere underneath the Paraná Magmatic Province (PMP) and conterminous geological provinces. Our analysis shows a consistent correlation between density and velocity anomalies. The P-wave speed and density are 1% and 15 kg/m3 lower, respectively, in the upper mantle under the Late Cretaceous to Cenozoic alkaline provinces, except beneath the Goiás Alkaline Province (GAP), where density (+20 kg/m3) and velocity (+0.5%) are relatively high. Underneath the PMP, the density is higher by about 50 kg/m3 in the north and 25 kg/m3 in the south, to a depth of 250 - 300 km. These values correlate with high-velocity perturbations of +0.5% and +0.3%, respectively. Profiles of density perturbation versus depth in the upper mantle are different for the PMP and the adjacent Archean São Francisco (SFC) and Amazonian (AC) cratons. The Paleoproterozoic PMP basement has a high-density root. The density is relatively low in the SFC and AC lithospheres. A reduction of density is a typical characteristic of chemically depleted Archean cratons. A more fertile Proterozoic and Phanerozoic subcontinental lithospheric mantle has a higher density, as deduced from density estimates of mantle xenoliths of different ages and composition. In conjunction with Re-Os isotopic studies of the PMP basalts, chemical and isotopic analyses of peridodite xenoliths from the GAP in the northern PMP, and electromagnetic induction experiments of the PMP lithosphere, our density and P-wave speed models suggest that the densification of the PMP lithosphere and flood basalt generation are related to mantle refertilization. Metasomatic refertilization resulted from the introduction of asthenospheric components from the mantle wedge above Proterozoic subduction zones, which surrounded the Paraná lithosphere

  20. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    Science.gov (United States)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  1. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    Science.gov (United States)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  2. High density and high temperature plasmas in Large Helical Device

    Science.gov (United States)

    Komori, Akio

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than ~ 1 × 1021 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  3. High density and high temperature plasmas in Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Komori, Akio, E-mail: komori@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than {approx} 1 x 10{sup 21} m{sup -3} is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is {approx} 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  4. Lagrangian temperature and vertical velocity fluctuations due to gravity waves in the lower stratosphere

    Science.gov (United States)

    Podglajen, Aurélien; Hertzog, Albert; Plougonven, Riwal; Legras, Bernard

    2016-04-01

    Wave-induced Lagrangian fluctuations of temperature and vertical velocity in the lower stratosphere are quantified using measurements from superpressure balloons (SPBs). Observations recorded every minute along SPB flights allow the whole gravity wave spectrum to be described and provide unprecedented information on both the intrinsic frequency spectrum and the probability distribution function of wave fluctuations. The data set has been collected during two campaigns coordinated by the French Space Agency in 2010, involving 19 balloons over Antarctica and 3 in the deep tropics. In both regions, the vertical velocity distributions depart significantly from a Gaussian behavior. Knowledge on such wave fluctuations is essential for modeling microphysical processes along Lagrangian trajectories. We propose a new simple parameterization that reproduces both the non-Gaussian distribution of vertical velocities (or heating/cooling rates) and their observed intrinsic frequency spectrum.

  5. Temperature, Pressure and Velocity measurements on the Ranque-Hilsch Vortex Tube

    Science.gov (United States)

    Liew, R.; Zeegers, J. C. H.; Kuerten, J. G. M.; Michałek, W. R.

    2012-11-01

    Temperatures, pressures and velocities were measured in a Ranque-Hilsch vortex tube. Results show that the cooling power is larger than the heating power due to a heat loss to the surroundings. This heat loss became the more dominant thermodynamic process at large cold fractions (the ratio of cold mass flow over total mass flow). The velocities were obtained by means of Laser Doppler Anemometry. By this method, the three dimensional velocities of the gas and their standard deviations in the vortex tube are revealed by an non-intrusive measurement method. The turbulent fluctuations, characterized by the standard deviations, show that the turbulence is isotropic in the core region of the vortex tube.

  6. Nonperturbative Yukawa theory at finite density and temperature

    CERN Document Server

    Fraga, Eduardo S; Pinto, Marcus Benghi

    2009-01-01

    In-medium Yukawa theory is part of the thermodynamics of the Standard Model of particle physics and is one of the main building blocks of most effective field theories of fermionic systems. By computing its pressure we investigate the nonperturbative thermodynamics at finite temperature and density using the optimized perturbation theory (OPT) framework. Our calculations are valid for arbitrary fermion and scalar masses, temperature, chemical potential, and not restricted to weak coupling. The model is considered in the presence as well as in the absence of condensates. Comparison with nonperturbative results shows that second order perturbation theory (PT) fails in the first case but performs rather well when condensates are absent, even at high-temperature regimes.

  7. Temperature fluctuation phenomena in a normally stagnant pipe connected downward to a high velocity and high temperature main pipe

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Akira, E-mail: a-naka@inss.co.jp [Institute of Nuclear Technology, Institute of Nuclear Safety System, Inc., 64 Sata Mihama-cho, Fukui 919-1205 (Japan); Miyoshi, Koji [Institute of Nuclear Technology, Institute of Nuclear Safety System, Inc., 64 Sata Mihama-cho, Fukui 919-1205 (Japan); Oumaya, Toru [Mechanical Engineering Group, Nuclear Power Division, Kansai Electric Power Co. Inc., 8 Yokota, 13 Goichi, Mihama-cho, Fukui 919-1141 (Japan); Takenaka, Nobuyuki; Hosokawa, Shigeo; Hamatani, Daisuke; Hase, Masatsugu; Onojima, Daisuke; Yamamoto, Yasuhiro; Saito, Atsushi [Department of Mechanical Engineering, Kobe University, 1-1 Rokkodai-cho, Higashinada-ku, Kobe 657-8501 (Japan)

    2014-04-01

    Highlights: • Flow patterns in a branch pipe with a closed end were observed by visualization. • The penetration length was investigated using experiments and numerical simulations. • The temperature fluctuation mechanism related to spiral flow was discussed. - Abstract: Numerous pipes branch off from the main pipes in power plant facilities. Main pipe flow initiates a cavity flow in a downward branch pipe with a closed end and a thermally stratified layer may form in the branch pipe if there is significant temperature difference in the main and branch pipe fluids. Fluctuation of a thermally stratified layer may initiate thermal fatigue crack in the branch pipe. In the present study, flow structures and temperature fluctuations in a branch pipe are investigated by experiments and numerical simulations to understand detailed behavior of the layer in a straight pipe and in a bent pipe. The penetration length of the main flow is measured for various main pipe flow velocities. The flow patterns in a straight pipe are divided into three regions by visualization with a tracer method, i.e., cavity flow in region 1, disturbed flow in the transition region, and spiral flow in region 2. The fluid temperature fluctuation in a straight pipe after the increase of main pipe flow velocity is attenuated in several hundred seconds since the thermal stratified layer goes down under the area into which the spiral vortex reaches. The fluid temperature in a bent pipe fluctuates when the spiral vortex reaches its lowest point after a long time period. Periodical velocity fluctuations during several tens second period are observed in the spiral flow. The mechanism of temperature fluctuation near the thermal stratified layer is considered with respect to the interference by the spiral flow and the fixed thermal stratified layer at the bent section by the cold water provided from the horizontal section.

  8. Effect of temperature on ultrasonic velocities of unconsolidated sandstones reservoirs during the SAGD recovery process

    Directory of Open Access Journals (Sweden)

    Delage P.

    2010-06-01

    Full Text Available The steam assisted gravity drainage (SAGD is a thermal in-situ technology that has been successfully used to enhance the recovery of heavy oil and bitumen in the Western Canada and in the Eastern Venezuela basins. Pressure and temperature variations during SAGD operations induce complex changes in the mechanical and acoustic properties of the reservoir rocks as well as of the caprock. To study these changes, measurements of ultrasonic wave velocities Vp, Vs were performed on both reconstituted samples and natural samples from oil sands reservoir. Reconstituted samples were made of Fontainebleau sands with a slight cementation formed by a silicate solution. They have a high porosity (about 30 % to 40 % and a high permeability (up to 10 D. Natural oil sands samples are unconsolidated sandstones extracted from the fluvio-estuarine McMurray Formation in Alberta (Canada. The saturating fluids were bitumen and glycerol with a strongly temperature dependent viscosity. The tests were carried out at different temperatures (in the range 40° and +86°C and at different effective pressures (from 12 bars up to 120 bars. Experimental results firstly showed that the elastic wave propagation velocities measured are strongly dependent on temperature and pore fluid viscosity whereas little effect of effective pressure was observed. Velocities decreased with increasing temperature and increased with increasing effective pressure. These effects are mainly due to the variations of the saturating fluids properties. Finally, the tests were modelled by using Ciz and Shapiro (2007 approach and satisfactory velocities values were obtained with highly viscous fluids, a case that cannot be easily explained by using the poro-elastic theory of Biot-Gassmann.

  9. Effect of temperature on ultrasonic velocities of unconsolidated sandstones reservoirs during the SAGD recovery process

    Science.gov (United States)

    Doan, D.-H.; Nauroy, J.-F.; Delage, P.; Mainguy, M.

    2010-06-01

    The steam assisted gravity drainage (SAGD) is a thermal in-situ technology that has been successfully used to enhance the recovery of heavy oil and bitumen in the Western Canada and in the Eastern Venezuela basins. Pressure and temperature variations during SAGD operations induce complex changes in the mechanical and acoustic properties of the reservoir rocks as well as of the caprock. To study these changes, measurements of ultrasonic wave velocities Vp, Vs were performed on both reconstituted samples and natural samples from oil sands reservoir. Reconstituted samples were made of Fontainebleau sands with a slight cementation formed by a silicate solution. They have a high porosity (about 30 % to 40 %) and a high permeability (up to 10 D). Natural oil sands samples are unconsolidated sandstones extracted from the fluvio-estuarine McMurray Formation in Alberta (Canada). The saturating fluids were bitumen and glycerol with a strongly temperature dependent viscosity. The tests were carried out at different temperatures (in the range 40° and +86°C) and at different effective pressures (from 12 bars up to 120 bars). Experimental results firstly showed that the elastic wave propagation velocities measured are strongly dependent on temperature and pore fluid viscosity whereas little effect of effective pressure was observed. Velocities decreased with increasing temperature and increased with increasing effective pressure. These effects are mainly due to the variations of the saturating fluids properties. Finally, the tests were modelled by using Ciz and Shapiro (2007) approach and satisfactory velocities values were obtained with highly viscous fluids, a case that cannot be easily explained by using the poro-elastic theory of Biot-Gassmann.

  10. How the Density Environment Changes the Influence of the Dark Matter–Baryon Streaming Velocity on Cosmological Structure Formation

    Science.gov (United States)

    Ahn, Kyungjin

    2016-10-01

    We study the dynamical effect of the relative velocity between dark matter and baryonic fluids, which remained supersonic after the epoch of recombination. The impact of this supersonic motion on the formation of cosmological structures was first formulated by Tseliakhovich & Hirata, in terms of the linear theory of small-scale fluctuations coupled to large-scale, relative velocities in mean-density regions. In their formalism, they limited the large-scale density environment to be that of the global mean density. We improve on their formulation by allowing variation in the density environment as well as the relative velocities. This leads to a new type of coupling between large-scale and small-scale modes. We find that the small-scale fluctuation grows in a biased way: faster in the overdense environment and slower in the underdense environment. We also find that the net effect on the global power spectrum of the density fluctuation is to boost its overall amplitude from the prediction by Tseliakhovich & Hirata. Correspondingly, the conditional mass function of cosmological halos and the halo bias parameter are both affected in a similar way. The discrepancy between our prediction and that of Tseliakhovich & Hirata is significant, and therefore, the related cosmology and high-redshift astrophysics should be revisited. The mathematical formalism of this study can be used for generating cosmological initial conditions of small-scale perturbations in generic, overdense (underdense) background patches.

  11. How Density Environment Changes the Influence of the Dark Matter-Baryon Streaming Velocity on the Cosmological Structure Formation

    CERN Document Server

    Ahn, Kyungjin

    2016-01-01

    We study the dynamical effect of relative velocities between dark matter and baryonic fluids, which remained supersonic after the epoch of recombination. The impact of this supersonic motion on the formation of cosmological structures was first formulated by Tseliakhovich & Hirata (2010), in terms of the linear theory of small-scale fluctuations coupled to large-scale, relative velocities in mean-density regions. In their formalism, they limited the large-scale density environment to be those of the global mean density. We improve on their formulation by allowing variation in the density environment as well as the relative velocities. This leads to a new type of coupling between large-scale and small-scale modes. We find that the small-scale fluctuation grows in a biased way: faster in the overdense environment and slower in the underdense environment. We also find that the net effect on the global power spectrum of the density fluctuation is to boost its overall amplitude from the prediction by Tseliakho...

  12. Measurements of temperature and velocity fluctuations in oscillating flows using thermal anemometry – application to thermoacoustic refrigerators

    OpenAIRE

    Berson, Arganthaël; Poignand, Gaelle; Jondeau, Emmanuel; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2012-01-01

    International audience; This paper summarizes our recent work on the development of thermal anemometry to measure velocity and temperature fluctuations in oscillating flows. First, we demonstrate that velocity cannot be measured accurately by hot-wire anemometry in oscillating flows when the flow reverses its direction. Indeed, there is no unique and well-defined correlation between the flow velocity and heat transfer near flow reversal, which prevents the recovery of velocity fluctuations fr...

  13. PT Symmetry and QCD: Finite Temperature and Density

    Directory of Open Access Journals (Sweden)

    Michael C. Ogilvie

    2009-04-01

    Full Text Available The relevance of PT symmetry to quantum chromodynamics (QCD, the gauge theory of the strong interactions, is explored in the context of finite temperature and density. Two significant problems in QCD are studied: the sign problem of finite-density QCD, and the problem of confinement. It is proven that the effective action for heavy quarks at finite density is PT-symmetric. For the case of 1+1 dimensions, the PT-symmetric Hamiltonian, although not Hermitian, has real eigenvalues for a range of values of the chemical potential μ, solving the sign problem for this model. The effective action for heavy quarks is part of a potentially large class of generalized sine-Gordon models which are non-Hermitian but are PT-symmetric. Generalized sine-Gordon models also occur naturally in gauge theories in which magnetic monopoles lead to confinement. We explore gauge theories where monopoles cause confinement at arbitrarily high temperatures. Several different classes of monopole gases exist, with each class leading to different string tension scaling laws. For one class of monopole gas models, the PT-symmetric affine Toda field theory emerges naturally as the effective theory. This in turn leads to sine-law scaling for string tensions, a behavior consistent with lattice simulations.

  14. Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

    Energy Technology Data Exchange (ETDEWEB)

    Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

    2008-10-29

    Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  15. Equation of state of fluid helium at high temperatures and densities

    Institute of Scientific and Technical Information of China (English)

    CAI; Lingcang; CHEN; Qifeng; GU; Yunjun; ZHANG; Ying; ZHOU

    2005-01-01

    Hugoniot curves and shock temperatures of gas helium with initial temperature 293 K and three initial pressures 0.6, 1.2, and 5.0 Mpa were measured up to 15000 K using a two-stage light-gas gun and transient radiation pyrometer. It was found that the calculated Hugoniot EOS of gas helium at the same initial pressure using Saha equation with Debye-Hückel correction was in good agreement with the experimental data. The curve of the calculated shock wave velocity with the particle velocity of gas helium which is shocked from the initial pressure 5 Mpa and temperature 293 K, I.e., the D~u relation, D = C0+λu (u < 10 km/s, λ = 1.32) in a low pressure region, is approximately parallel with the fitted D~u (λ = 1.36) of liquid helium from the experimental data of Nellis et al. Our calculations show that the Hugoniot parameterλis independent of the initial density ρ0. The D~u curves of gas helium will transfer to another one and approach a limiting value of compression when their temperature elevates to about 18000 K and the ionization degree of the shocked gas helium reaches 10-3.

  16. Low density lipoproteins as circulating fast temperature sensors.

    Directory of Open Access Journals (Sweden)

    Ruth Prassl

    Full Text Available BACKGROUND: The potential physiological significance of the nanophase transition of neutral lipids in the core of low density lipoprotein (LDL particles is dependent on whether the rate is fast enough to integrate small (+/-2 degrees C temperature changes in the blood circulation. METHODOLOGY/PRINCIPAL FINDINGS: Using sub-second, time-resolved small-angle X-ray scattering technology with synchrotron radiation, we have monitored the dynamics of structural changes within LDL, which were triggered by temperature-jumps and -drops, respectively. Our findings reveal that the melting transition is complete within less than 10 milliseconds. The freezing transition proceeds slowly with a half-time of approximately two seconds. Thus, the time period over which LDL particles reside in cooler regions of the body readily facilitates structural reorientation of the apolar core lipids. CONCLUSIONS/SIGNIFICANCE: Low density lipoproteins, the biological nanoparticles responsible for the transport of cholesterol in blood, are shown to act as intrinsic nano-thermometers, which can follow the periodic temperature changes during blood circulation. Our results demonstrate that the lipid core in LDL changes from a liquid crystalline to an oily state within fractions of seconds. This may, through the coupling to the protein structure of LDL, have important repercussions on current theories of the role of LDL in the pathogenesis of atherosclerosis.

  17. A perovskitic lower mantle inferred from high-pressure, high-temperature sound velocity data.

    Science.gov (United States)

    Murakami, Motohiko; Ohishi, Yasuo; Hirao, Naohisa; Hirose, Kei

    2012-05-02

    The determination of the chemical composition of Earth's lower mantle is a long-standing challenge in earth science. Accurate knowledge of sound velocities in the lower-mantle minerals under relevant high-pressure, high-temperature conditions is essential in constraining the mineralogy and chemical composition using seismological observations, but previous acoustic measurements were limited to a range of low pressures and temperatures. Here we determine the shear-wave velocities for silicate perovskite and ferropericlase under the pressure and temperature conditions of the deep lower mantle using Brillouin scattering spectroscopy. The mineralogical model that provides the best fit to a global seismic velocity profile indicates that perovskite constitutes more than 93 per cent by volume of the lower mantle, which is a much higher proportion than that predicted by the conventional peridotitic mantle model. It suggests that the lower mantle is enriched in silicon relative to the upper mantle, which is consistent with the chondritic Earth model. Such chemical stratification implies layered-mantle convection with limited mass transport between the upper and the lower mantle.

  18. Temperature and velocity fields in natural convection by PIV and LIF

    DEFF Research Database (Denmark)

    Meyer, Knud Erik; Larsen, Poul Scheel; Westergaard, C. H.

    2002-01-01

    Natural convection in a cubical cavity (L = 250 mm) filled with water is created by heating a square plate (0.5 L) centred in the bottom wall and by cooling the sidewalls, while the remaining walls are insulated. The Rayleigh number based on cavity side length and temperature difference between...... plate and cooled walls is 1.4×10^10. The flow is turbulent and is similar to some indoor room flows. Combined Particle Image Velocimetry (PIV) and Planar Light Induced Fluorescence (LIF) are used to measure local velocities and temperatures. Data measured in a symmetry plane parallel to a sidewall...

  19. The effect of the impactor diameter and temperature on low velocity impact behavior of CFRP laminates

    Science.gov (United States)

    Evci, C.; Uyandıran, I.

    2017-02-01

    Impact damage is one of the major concerns that should be taken into account with the new aircraft and spacecraft structures which employ ever-growing use of composite materials. Considering the thermal loads encountered at different altitudes, both low and high temperatures can affect the properties and impact behavior of composite materials. This study aims to investigate the effect of temperature and impactor diameter on the impact behavior and damage development in balanced and symmetrical CFRP laminates which were manufactured by employing vacuum bagging process with autoclave cure. Instrumented drop-weight impact testing system is used to perform the low velocity impact tests in a range of temperatures ranged from 60 down to -50 °C. Impact tests for each temperature level were conducted using three different hemispherical impactor diameters varying from 10 to 20 mm. Energy profile method is employed to determine the impact threshold energies for damage evolution. The level of impact damage is determined from the dent depth on the impacted face and delamination damage detected using ultrasonic C-Scan technique. Test results reveal that the threshold of penetration energy, main failure force and delamination area increase with impactor diameter at all temperature levels. No clear influence of temperature on the critical force thresholds could be derived. However, penetration threshold energy decreased as the temperature was lowered. Drop in the penetration threshold was more obvious with quite low temperatures. Delamination damage area increased while the temperature decreased from +60 °C to -50 °C.

  20. Density and velocity relationships for digital sonic and density logs from coastal Washington and laboratory measurements of Olympic Peninsula mafic rocks and greywackes

    Science.gov (United States)

    Brocher, Thomas M.; Christensen, Nikolas I.

    2001-01-01

    Three-dimensional velocity models for the basins along the coast of Washington and in Puget Lowland provide a means for better understanding the lateral variations in strong ground motions recorded there. We have compiled 16 sonic and 18 density logs from 22 oil test wells to help us determine the geometry and physical properties of the Cenozoic basins along coastal Washington. The depth ranges sampled by the test-well logs fall between 0.3 and 2.1 km. These well logs sample Quaternary to middle Eocene sedimentary rocks of the Quinault Formation, Montesano Formation, and Hoh rock assemblage. Most (18 or 82%) of the wells are from Grays Harbor County, and many of these are from the Ocean City area. These Grays Harbor County wells sample the Quinault Formation, Montesano Formation, and frequently bottom in the Hoh rock assemblage. These wells show that the sonic velocity and density normally increase significantly across the contacts between the Quinault or the Montesano Formations and the Hoh rock assemblage. Reflection coefficients calculated for vertically traveling compressional waves from the average velocities and densities for these units suggest that the top of the Hoh rock assemblage is a strong reflector of downward-propagating seismic waves: these reflection coefficients lie between 11 and 20%. Thus, this boundary may reflect seismic energy upward and trap a substantial portion of the seismic energy generated by future earthquakes within the Miocene and younger sedimentary basins found along the Washington coast. Three wells from Jefferson County provide data for the Hoh rock assemblage for the entire length of the logs. One well (Eastern Petroleum Sniffer Forks #1), from the Forks area in Clallam County, also exclusively samples the Hoh rock assemblage. This report presents the locations, elevations, depths, stratigraphic, and other information for all the oil test wells, and provides plots showing the density and sonic velocities as a function of depth

  1. Velocity of detonation at any initial density without using heat of formation of explosives.

    Science.gov (United States)

    Keshavarz, Mohammad Hossein; Mofrad, Reza Teimuri; Alamdari, Reza Fareghi; Moghadas, Mohammad Hassan; Mostofizadeh, Ali Reza; Sadeghi, Hossein

    2006-10-11

    The simplest method is introduced for reliable estimating the detonation velocity of large class of CHNO explosives based elemental composition and specific structural groups. There is no need to use heat of formation and the other experimental data for calculation of detonation velocity in the new procedure. Only elemental composition and the number of special structural groups without using heat of formation of explosive is sufficient for reliable desk calculation of detonation velocity. The results show good agreement with experimental values with respect to computed results obtained by complex computer code using BKWS and BKWR equations of state. Predicted velocities of detonation have root-mean-square (rms) percent deviation of 2.2, 5.9 and 5.3 from experimental data for new method, BKWS and BKWR equations of state, respectively.

  2. Electron temperature and density probe for small aeronomy satellites

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, K.-I. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan (China); International Center for Space Weather Study and education, Kyushu University, Fukuoka (Japan); Hsu, Y. W.; Jiang, G. S.; Chen, W. H.; Liu, W. T. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Cheng, C. Z.; Fang, H. K. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan (China)

    2015-08-15

    A compact and low power consumption instrument for measuring the electron density and temperature in the ionosphere has been developed by modifying the previously developed Electron Temperature Probe (ETP). A circuit block which controls frequency of the sinusoidal signal is added to the ETP so that the instrument can measure both T{sub e} in low frequency mode and N{sub e} in high frequency mode from the floating potential shift of the electrode. The floating potential shift shows a minimum at the upper hybrid resonance frequency (f{sub UHR}). The instrument which is named “TeNeP” can be used for tiny satellites which do not have enough conductive surface area for conventional DC Langmuir probe measurements. The instrument also eliminates the serious problems associated with the contamination of satellite surface as well as the sensor electrode.

  3. Electron temperature and density probe for small aeronomy satellites

    Science.gov (United States)

    Oyama, K.-I.; Hsu, Y. W.; Jiang, G. S.; Chen, W. H.; Cheng, C. Z.; Fang, H. K.; Liu, W. T.

    2015-08-01

    A compact and low power consumption instrument for measuring the electron density and temperature in the ionosphere has been developed by modifying the previously developed Electron Temperature Probe (ETP). A circuit block which controls frequency of the sinusoidal signal is added to the ETP so that the instrument can measure both Te in low frequency mode and Ne in high frequency mode from the floating potential shift of the electrode. The floating potential shift shows a minimum at the upper hybrid resonance frequency (fUHR). The instrument which is named "TeNeP" can be used for tiny satellites which do not have enough conductive surface area for conventional DC Langmuir probe measurements. The instrument also eliminates the serious problems associated with the contamination of satellite surface as well as the sensor electrode.

  4. On the Determination of the Gas Temperature From the Velocity of the Muzzle Rarefaction Wave

    Science.gov (United States)

    1983-02-01

    0.09 The mixture is characterized by the following values, Pressure : Density: Temperature: Ratio of Specific Heats Molecular Weight: Covolume ...the cited value of Tv:Lk ~ 5.5 x lO"^ sec at 1 atmosphere and the inverse dependence on pressure , the present example involving a pressure of 188...discharge the propulsion gas has a temperature of approximately 1800oK, for a typical high zone howitzer charge, and a pressure of 50 MPa. The release of

  5. High power densities from high-temperature material interactions

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs) offer important and unique advantages in terrestrial and space energy processing. And they are well suited to serve together synergistically. TEC and MFHPs operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: high-temperature material effects determine the level and lifetime of performance. Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs - and point to significant improvements with anticipated technological gains.

  6. Survival of charged rho condensation at high temperature and density

    CERN Document Server

    Liu, Hao; Huang, Mei

    2015-01-01

    The charged vector $\\rho$ mesons in the presence of external magnetic fields at finite temperature $T$ and chemical potential $\\mu$ have been investigated in the framework of the Nambu--Jona-Lasinio model. We compute the masses of charged $\\rho$ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential. The self-energy of the $\\rho$ meson contains the quark-loop contribution, i.e. the leading order contribution in $1/N_c$ expansion. The charged $\\rho$ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field $eB_c$, which means that the charged vector meson condensation, i.e. the electromagnetic superconductor can be induced above the critical magnetic field. Surprisingly, it is found that the charged $\\rho$ condensation can even survive at high temperature and density. At zero temperature, the critical magnetic field just increases slightly with the chemical potential, which indicates that the charged $\\rho$ condensatio...

  7. Binary Collision Density in a Non-Ideal Gas as a Function of Particle Density, Collision Diameter, and Temperature

    Science.gov (United States)

    Mohazzabi, Pirooz

    2017-09-01

    Using molecular dynamics simulations, binary collision density in a dense non-ideal gas with Lennard-Jones interactions is investigated. It is shown that the functional form of the dependence of collision density on particle density and collision diameter remains the same as that for an ideal gas. The temperature dependence of the collision density, however, has a very different form at low temperatures, where it decreases as temperature increases. But at higher temperatures the functional form becomes the same as that for an ideal gas.

  8. Simulation of Velocity and Temperature Distributions of Displacement Ventilation System with Single or Double Heat Sources

    Institute of Scientific and Technical Information of China (English)

    Wenfei Wu; Xuan Wu; Yanhui Feng; Xinxin Zhang

    2007-01-01

    In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can't be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can't be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered.

  9. Tidal reversal and flow velocities using temperature and specific conductance in a small wetland creek

    Science.gov (United States)

    Eaton, Timothy T.

    2016-11-01

    Characterizing flow dynamics in very small tidal creeks is complicated and not well suited to methods developed for upland streams or coastal estuaries, due to low flows, bidirectionality and shallow waters. Simple instrumentation enables thermal and salinity signals to be used to observe flow directions and estimate velocities in these settings. Using multiple inexpensive sensors over 500 m along a tidally influenced wetland creek, I demonstrate how advection of temperature and specific conductance pulses reveal flood and ebb tides and the temporary reversal of flow by warmer, estuarine water from the receiving embayment. The sequential rise of temperature upstream was most evident under hot and dry conditions, after daily peak air temperatures of 25 °C or above, and was subdued or disrupted under cooler or rainy conditions in summertime. Changes in specific conductance at successive sites upstream were less susceptible to environmental influences and confirm tidal flood velocity of between 0.07 and 0.37 m/s. The tidally-induced flow reversal suggests that periodic high tide conditions can interfere with rapid dispersal of pollution discharges, such as from the combined sewer overflow (CSO) located upstream of the studied creek reach. This low-cost approach of temperature and specific conductance sensing in vegetated coastal wetlands where access, precise elevation control and creek discharge measurements are difficult, provides a simple way of tracking water masses when sufficient contrast exists between water sources.

  10. Stereoscopy of dust density waves under microgravity: Velocity distributions and phase-resolved single-particle analysis

    Energy Technology Data Exchange (ETDEWEB)

    Himpel, Michael, E-mail: himpel@physik.uni-greifswald.de; Killer, Carsten; Melzer, André [Institute of Physics, Ernst-Moritz-Arndt-University, 17489 Greifswald (Germany); Bockwoldt, Tim; Piel, Alexander [IEAP, Christian-Albrechts-Universität Kiel, D-24098 Kiel (Germany); Ole Menzel, Kristoffer [ABB Switzerland Ltd, Corporate Research Center, 5405 Dättwil (Switzerland)

    2014-03-15

    Experiments on dust-density waves have been performed in dusty plasmas under the microgravity conditions of parabolic flights. Three-dimensional measurements of a dust density wave on a single particle level are presented. The dust particles have been tracked for many oscillation periods. A Hilbert analysis is applied to obtain trajectory parameters such as oscillation amplitude and three-dimensional velocity amplitude. While the transverse motion is found to be thermal, the velocity distribution in wave propagation direction can be explained by harmonic oscillations with added Gaussian (thermal) noise. Additionally, it is shown that the wave properties can be reconstructed by means of a pseudo-stroboscopic approach. Finally, the energy dissipation mechanism from the kinetic oscillation energy to thermal motion is discussed and presented using phase-resolved analysis.

  11. Simultaneous measurement of temperature and velocity of air flow over 1000°C using two color phosphor thermometry

    Science.gov (United States)

    Fukuta, Masatoshi; Someya, Satoshi; Munakata, Tetsuo; LCS Team

    2016-11-01

    Thermal barrier coatings were applied to the gas turbines and the internal combustion engines for the high thermal efficiency. The evaluation and the improvement of coatings require to measure transient gaseous flow near the wall with coatings. An aim of this study is to combine a two color phosphor thermometry with the PIV to measure simultaneously temperature and velocity of the gas over 1000°C. The temperature and velocity distribution of an impinging jet of high temperature air was simultaneously visualized in experiments. The temperature was estimated from an intensity ratio of luminescent in different ranges of wavelength, 500 600 nm and 400 480 nm. Uncertainty of measured temperature was less than 10°C. Temperatures measured by the developed method and by thermocouples were agreed well. The measured velocity by the PIV with phosphor particles were also agreed well with the velocity measured by a Laser Doppler Velocimeter.

  12. Diagnostic developments for velocity and temperature measurements in uni-element rocket environments

    Science.gov (United States)

    Philippart, Kenneth D.

    1995-08-01

    Velocity and temperature measurements were taken within a uni-element rocket combustion chamber for hydrogen-oxygen propellants using laser Doppler velocimetry, thermocouples, and a thermocouple-based temperature rake developed for this effort. Velocity and turbulence profiles were obtained for firings with a gaseous oxygen (GO2)/gaseous hydrogen (GH2) coaxial shear injector at axial locations of 1.6 mm (0.063 in.), 6.4 mm (0.25 in.), 12.7 mm (0.5 in.), 25.4 mm (1 in.) and 50.8 mm (2 in.). Aluminum oxide particles of various sizes seeded the flow in an attempt to explain the discrepancies. While cold-flow simulations were promising, hot-fire results for the various particles were virtually identical and still lower than earlier data. The hot-firings were self-consistent and question the reproducibility of the previous data. Velocity measurements were made closer to the injector than the preceding work. Asymmetries were noted in all profiles. The shear layer displayed high turbulence levels. The central flow near the injector resembled turbulent pipe flow. Recirculation zones existed at the chamber walls and became smaller as the flow evolved downstream. The combusting flow region expanded with increasing axial distance. A thermocouple-instrumented coaxial injector was fired with GO2/GH2 propellants. The injector exit plane boundary conditions were determined. The feasibility of a thermocouple-based temperature rake was established. Tests at three axial positions for air/GM2 firings revealed asymmetric profiles. Temperatures increased with increasing axial distance.

  13. Electric field dependence of drift velocity and electron temperature of GaAs/AlGaAs 2DEG in the low electric field region

    Energy Technology Data Exchange (ETDEWEB)

    Ari, Mehmet; Turkoglu, Orhan

    2004-05-01

    Experimental and theoretical results on low electric field transport of two-dimensional electron gas (2DEG) in AlGaAs/GaAs high electron mobility transistor (HEMT) channel are reported at lattice temperature T{sub L}=1.7 K under zero magnetic field. The electron temperature (T{sub e}) and the drift velocity ({upsilon}{sub d}) dependence on the electric field (F) and the electron density in the 2DEG channel are presented. In addition, the variation of the electron temperature with the drift velocity is obtained. The results are obtained for the electric field in the region of 0.01-100 V/cm and in the electron temperature range of 1.7-60 K. It is shown that the electron temperature of 2DEG is a non-monotonous function of the electric field. The results also indicate that electron heating is seen to occur for the electric field F>0.1 V/cm which corresponds to the electron temperature T{sub e}=2 K. A sharp increase in the electron temperature T{sub e} and in the drift velocity {upsilon}{sub d} with the electric field below electron temperature of 40 K is seen. The variation of electron temperature with drift velocity is very slow in the same electron temperature range where acoustic phonon emission due to deformation potential is the dominant energy loss mechanism of electronic system. When F>5 V/cm and T{sub e}>40 K, where the optic phonon emission is a dominant relaxation mechanism, the electron temperature changes linearly with electric field and the drift velocity increases very rapidly with electron temperature. Also, the drift velocity starts to saturate in this regime. The experimental results are compared with theoretical results and a good agreement is obtained at the electron temperatures of T{sub e}<50 K. Above the electron temperature of 50 K, a disagreement is observed between the experimental and the theoretical results which indicates that additional scattering mechanisms should be taken into account and the accuracy of the assumptions concerning the

  14. The Effect of Atmospheric Cooling on Vertical Velocity Dispersion and Density Distribution of Brown Dwarfs

    Science.gov (United States)

    Ryan, Russell E., Jr.; Thorman, Paul A.; Schmidt, Sarah J.; Cohen, Seth H.; Hathi, Nimish P.; Holwerda, Benne W.; Lunine, Jonathan I.; Pirzkal, Nor; Windhorst, Rogier A.; Young, Erick

    2017-09-01

    We present a Monte Carlo simulation designed to predict the vertical velocity dispersion of brown dwarfs in the Milky Way. We show that since these stars are constantly cooling, the velocity dispersion has a noticeable trend with the spectral type. With realistic assumptions for the initial mass function, star formation history, and the cooling models, we show that the velocity dispersion is roughly consistent with what is observed for M dwarfs, decreases to cooler spectral types, and increases again for the coolest types in our study (∼T9). We predict a minimum in the velocity dispersions for L/T transition objects, however, the detailed properties of the minimum predominately depend on the star formation history. Since this trend is due to brown dwarf cooling, we expect that the velocity dispersion as a function of spectral type should deviate from the constancy around the hydrogen-burning limit. We convert from velocity dispersion to vertical scale height using standard disk models and present similar trends in disk thickness as a function of spectral type. We suggest that future, wide-field photometric and/or spectroscopic missions may collect sizable samples of distant (∼ 1 kpc) dwarfs that span the hydrogen-burning limit. As such, we speculate that such observations may provide a unique way of constraining the average spectral type of hydrogen burning. Support for program #13266 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.

  15. Tribological properties of high velocity arc sprayed Fe-Al based composite coatings at elevated temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; ZHANG Shu; XU Wei-pu; ZU Zi-xin; XU Bin-shi

    2004-01-01

    Fe-Al based intermetallic composite coatings were in-situ synthesized using Fe-Al/Cr3C2 or Fe-Al/WC cored wires and high velocity are spraying (HVAS) technology. The tribological properties of the Fe-Al based intermetallic composite coatings were investigated using a ball-on-disc tribotester from room temperature to 650 ℃. The results show that the coatings have relatively high bond strength and micro-hardness. The tribological properties of Fe-Al/Cr3C2 and Fe-Al/WC composite coatings were further analyzed and compared. Low and stable wear rates of the Fe-Al based intermetallic composite coatings were indicated from room temperature to 650 ℃. The excellent wear resistance of the composite coatings in high temperature was discussed.

  16. Si iv Column Densities Predicted from Non-Equilibrium Ionization Simulations of Turbulent Mixing Layers and High-Velocity Clouds

    CERN Document Server

    Kwak, Kyujin; Henley, David B

    2015-01-01

    We present predictions of the Si iv ions in turbulent mixing layers (TMLs) between hot and cool gas and in cool high-velocity clouds (HVCs) that travel through a hot halo, complementing the C iv, N v, and O vi predictions in Kwak & Shelton, Kwak et al., and Henley et al. We find that the Si iv ions are most abundant in regions where the hot and cool gases first begin to mix or where the mixed gas has cooled significantly. The predicted column densities of high velocity Si iv and the predicted ratios of Si iv to C iv and O vi found on individual sightlines in our HVC simulations are in good agreement with observations of high velocity gas. Low velocity Si iv is also seen in the simulations, as a result of decelerated gas in the case of the HVC simulations and when looking along directions that pass perpendicular to the direction of motion in the TML simulations. The ratios of low velocity Si iv to C iv and O vi in the TML simulations are in good agreement with those recorded for Milky Way halo gas, while t...

  17. The relation between gas density and velocity power spectra in galaxy clusters: high-resolution hydrodynamic simulations and the role of conduction

    CERN Document Server

    Gaspari, M; Nagai, D; Lau, E T; Zhuravleva, I

    2014-01-01

    Exploring the ICM power spectrum can help us to probe the physics of galaxy clusters. Using high-resolution 3D plasma simulations, we study the statistics of the velocity field and its relation with the thermodynamic perturbations. The normalization of the ICM spectrum (density, entropy, or pressure) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification. For low 3D Mach number M~0.25, gravity waves mainly drive entropy perturbations, traced by preferentially tangential turbulence. For M>0.5, sound waves start to significantly contribute, passing the leading role to compressive pressure fluctuations, associated with isotropic turbulence (or a slight radial bias). Density and temperature fluctuations are then characterized by the dominant process: isobaric (low M), adiabatic (high M), or isothermal (strong conduction). Most clusters reside in the intermediate regime, showing a mixture of gravity and sound waves, hence drifting towards isotropic vel...

  18. Dynamics of Air Temperature, Velocity and Ammonia Emissions in Enclosed and Conventional Pig Housing Systems

    Directory of Open Access Journals (Sweden)

    J. I. Song

    2013-03-01

    Full Text Available This study aimed to compare the dynamics of air temperature and velocity under two different ventilation and housing systems during summer and winter in Korea. The NH3 concentration of both housing systems was also investigated in relation to the pig’s growth. The ventilation systems used were; negative pressure type for the enclosed pig house (EPH and natural airflow for the conventional pig house (CPH. Against a highly fluctuating outdoor temperature, the EPH was able to maintain a stable temperature at 24.8 to 29.1°C during summer and 17.9 to 23.1°C during winter whilst the CPH had a wider temperature variance during summer at 24.7 to 32.3°C. However, the temperature fluctuation of the CPH during winter was almost the same with that of EPH at 14.5 to 18.2°C. The NH3 levels in the CPH ranged from 9.31 to 16.9 mg/L during summer and 5.1 to 19.7 mg/L during winter whilst that of the EPH pig house was 7.9 to 16.1 mg/L and 3.7 to 9.6 mg/L during summer and winter, respectively. These values were less than the critical ammonia level for pigs with the EPH maintaining a lower level than the CPH in both winter and summer. The air velocity at pig nose level in the EPH during summer was 0.23 m/s, enough to provide comfort because of the unique design of the inlet feature. However, no air movement was observed in almost all the lower portions of the CPH during winter because of the absence of an inlet feature. There was a significant improvement in weight gain and feed intake of pigs reared in the EPH compared to the CPH (p<0.05. These findings proved that despite the difference in the housing systems, a stable indoor temperature was necessary to minimize the impact of an avoidable and highly fluctuating outdoor temperature. The EPH consistently maintained an effective indoor airspeed irrespective of season; however the CPH had defective and stagnant air at pig nose level during winter. Characteristics of airflow direction and pattern were

  19. Density and Viscosity Measurement of Diesel Fuels at Combined High Pressure and Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Carl Schaschke

    2013-07-01

    Full Text Available We report the measurement of the viscosity and density of various diesel fuels, obtained from British refineries, at elevated pressures up to 500 MPa and temperatures in the range 298 K to 373 K. The measurement and prediction procedures of fluid properties under high pressure conditions is of increasing interest in many processes and systems including enhanced oil recovery, automotive engine fuel injection, braking, and hydraulic systems. Accurate data and understanding of the fluid characteristic in terms of pressure, volume and temperature is required particularly where the fluid is composed of a complex mixture or blend of aliphatic or aromatic hydrocarbons. In this study, high pressure viscosity data was obtained using a thermostatically-controlled falling sinker-type high pressure viscometer to provide reproducible and reliable viscosity data based on terminal velocity sinker fall times. This was supported with density measurements using a micro-pVT device. Both high-pressure devices were additionally capable of illustrating the freezing points of the hydrocarbon mixtures. This work has, thus, provided data that can extend the application of mixtures of commercially available fuels and to test the validity of available predictive density and viscosity models. This included a Tait-style equation for fluid compressibility prediction. For complex diesel fuel compositions, which have many unidentified components, the approach illustrates the need to apply appropriate correlations, which require accurate knowledge or prediction of thermodynamic properties.

  20. Techniques for Transition and Surface Temperature Measurements on Projectiles at Hypersonic Velocities- A Status Report

    Science.gov (United States)

    Wilder, M. C.; Bogdanoff, D. W.

    2005-01-01

    A research effort to advance techniques for determining transition location and measuring surface temperatures on graphite-tipped projectiles in hypersonic flight in a ballistic range is described. Projectiles were launched at muzzle velocities of approx. 4.7 km/sec into air at pressures of 190-570 Torr. Most launches had maximum pitch and yaw angles of 2.5-5 degrees at pressures of 380 Torr and above and 3-6 degrees at pressures of 190-380 Torr. Arcjet-ablated and machined, bead-blasted projectiles were launched; special cleaning techniques had to be developed for the latter class of projectiles. Improved methods of using helium to remove the radiating gas cap around the projectiles at the locations where ICCD (intensified charge coupled device) camera images were taken are described. Two ICCD cameras with a wavelength sensitivity range of 480-870 nm have been used in this program for several years to obtain images. In the last year, a third camera, with a wavelength sensitivity range of 1.5-5 microns [in the infrared (IR)], has been added. ICCD and IR camera images of hemisphere nose and 70 degree sphere-cone nose projectiles at velocities of 4.0-4.7 km/sec are presented. The ICCD images clearly show a region of steep temperature rise indicative of transition from laminar to turbulent flow. Preliminary temperature data for the graphite projectile noses are presented.

  1. Flow and heat transfer of nanofluids over a rotating porous disk with velocity slip and temperature jump

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Chenguang; Zheng, Liancun [Univ. of Science and Technology Beijing (China). School of Mathematics and Physics; Zhang, Chaoli [Univ. of Science and Technology Beijing (China). School of Mathematics and Physics; Univ. of Science and Technology Beijing (China). School of Mechanical Engineering; Zhang, Xinxin [Univ. of Science and Technology Beijing (China). School of Mechanical Engineering

    2015-09-01

    In this article, we discuss the flow and heat transfer of nanofluids over a rotating porous disk with velocity slip and temperature jump. Three types of nanoparticles - Cu, Al{sub 2}O{sub 3}, and CuO - are considered with water as the base fluid. The nonlinear governing equations are reduced into ordinary differential equations by Von Karman transformations and solved using homotopy analysis method (HAM), which is verified in good agreement with numerical ones. The effects of involved parameters such as porous parameter, velocity slip, temperature jump, as well as the types of nanofluids on velocity and temperature fields are presented graphically and analysed.

  2. Lattice QCD at finite temperature and density from Taylor expansion

    Science.gov (United States)

    Steinbrecher, Patrick

    2017-01-01

    In the first part, I present an overview of recent Lattice QCD simulations at finite temperature and density. In particular, we discuss fluctuations of conserved charges: baryon number, electric charge and strangeness. These can be obtained from Taylor expanding the QCD pressure as a function of corresponding chemical potentials. Our simulations were performed using quark masses corresponding to physical pion mass of about 140 MeV and allow a direct comparison to experimental data from ultra-relativistic heavy ion beams at hadron colliders such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. In the second part, we discuss computational challenges for current and future exascale Lattice simulations with a focus on new silicon developments from Intel and NVIDIA.

  3. Extended Opacity Tables with Higher Temperature-Density-Frequency Resolution

    Science.gov (United States)

    Schillaci, Mark; Orban, Chris; Delahaye, Franck; Pinsonneault, Marc; Nahar, Sultana; Pradhan, Anil

    2015-05-01

    Theoretical models for plasma opacities underpin our understanding of radiation transport in many different astrophysical objects. These opacity models are also relevant to HEDP experiments such as ignition scale experiments on NIF. We present a significantly expanded set of opacity data from the widely utilized Opacity Project, and make these higher resolution data publicly available through OSU's portal with dropbox.com. This expanded data set is used to assess how accurate the interpolation of opacity data in temperature-density-frequency dimensions must be in order to adequately model the properties of most stellar types. These efforts are the beginning of a larger project to improve the theoretical opacity models in light of experimental results at the Sandia Z-pinch showing that the measured opacity of Iron disagrees strongly with all current models.

  4. Experimental charge density of hematite in its magnetic low temperature and high temperature phases.

    Science.gov (United States)

    Theissmann, R; Fuess, H; Tsuda, K

    2012-09-01

    Structural parameters of hematite (α-Fe(2)O(3)), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Experimental charge density of hematite in its magnetic low temperature and high temperature phases

    Energy Technology Data Exchange (ETDEWEB)

    Theissmann, R., E-mail: ralf.theissmann@kronosww.com [Faculty of Engineering and CeNIDE (Center for NanoIntegration Duisburg-Essen), University of Duisburg-Essen, Bismarckstr. 81, 47057 Duisburg (Germany); Fuess, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Tsuda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, 980-8577 Sendai (Japan)

    2012-09-15

    Structural parameters of hematite ({alpha}-Fe{sub 2}O{sub 3}), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90 K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. -- Highlights: Black-Right-Pointing-Pointer Quantitative CBED was used to study hematite ({alpha}-Fe2O3). Black-Right-Pointing-Pointer Structure and charge density of both antiferromagnetic phases were investigated. Black-Right-Pointing-Pointer Topological charge density analysis was combined with a Bader analysis. Black-Right-Pointing-Pointer A transition from a Mott-Hubbard to a charge transfer insulator is proposed. Black-Right-Pointing-Pointer A frustrated triangular magnetic coupling in the oxygen planes is proposed.

  6. The nearby spiral density-wave structure of the Galaxy: line-of-sight and longitudinal velocities of 223 Cepheids

    Science.gov (United States)

    Griv, Evgeny; Hou, Li-Gang; Jiang, Ing-Guey; Ngeow, Chow-Choong

    2017-02-01

    The data of 223 stars within 4 kpc from the Sun and 400 pc from the plane are collected from Melnik et al., who listed photometric distances and velocities of 674 long-period Cepheids in the disc of our Galaxy. Both line-of-sight and transverse along the Galactic longitude velocities of the selected stars are analysed on the assumption that the system is the subject to Lin-Shu-type moderately unstable, low-amplitude, tightly wound and rigidly rotating density waves. Minimization of the least-squares estimator S of measured and modelled velocities of stars was performed in the geometrical parameters of waves. The wave structures defined from the two independent samples of velocities are nearly similar. Different radial scales (wavelengths) of velocity inhomogeneity of about 1, 2 and 4 kpc, which do not depend on the number of spiral arms m, were found. But for now it is unclear if one can identify these scales as fully independent global modes of collective oscillations or they are Fourier harmonics of a single wave, or they just reveal the segments of large-scale Orion, Sagittarius and Perseus arms. The dominant mode is the one-armed wave for the main minimum of all S considered. However, because the S values for fits with m = 1-4 are almost equal the latter conclusion must be regarded as tentative until more extensive data are available. High-precision Gaia observations could reveal in the near future whether the wave-like velocity fluctuations near the Sun reported here do indeed exist.

  7. Density structure of the cratonic mantle in Southern Africa. 2. Correlations with kimberlite distribution, seismic velocities, and Moho sharpness

    DEFF Research Database (Denmark)

    Artemieva, Irina; Vinnik, Lev

    2016-01-01

    across) lowdensity (down to 3.34 g/cm3) and high-density (up to 3.41 g/cm3) anomalies. High (3.40–3.42 g/cm3) mantle densities beneath the Eastern Cape Fold belt require the presence of a significant amount of eclogite in the mantle, such as associated with subducted oceanic slabs. We find a strong...... the composition and rheology of the lithospheric mantle to make it unfavorable for consequent kimberlite eruptions. (5) Density anomalies in the lithospheric mantle show inverse correlation with seismic Vp, Vs velocities at 100–150 km depth. However, this correlation is weaker than reported in experimental...

  8. Human preference and acceptance of increased air velocity to offset warm sensation at increased room temperatures

    DEFF Research Database (Denmark)

    Cattarin, Giulio; Simone, Angela; Olesen, Bjarne W.

    . The present climatic chamber study examined energy performance and achievable thermal comfort of traditional and bladeless desk fans. Different effects of mechanical and simulated-natural airflow patterns were also investigated. 32 Scandinavians, performing office activities and wearing light clothes , were......Previous studies have demonstrated that in summertime increased air velocities can compensate for higher room temperatures to achieve comfortable conditions. In order to increase air movement, windows opening, ceiling or desk fans can be used at the expense of relatively low energy consumption...... exposed to a increased air movement generated by a personal desk fan. The subjects could continuously regulate the fans under three fixed environmental conditions (operative temperatures equal to 26 °C, 28 °C, or 30 °C, and same absolute humidity 12.2 g/m3). The experimental study showed that increased...

  9. Impact of temperature-velocity distribution on fusion neutron peak shape

    Science.gov (United States)

    Munro, D. H.; Field, J. E.; Hatarik, R.; Peterson, J. L.; Hartouni, E. P.; Spears, B. K.; Kilkenny, J. D.

    2017-05-01

    Doppler broadening of the 14 MeV DT and 2.45 MeV DD fusion neutron lines has long been our best measure of temperature in a burning plasma. At the National Ignition Facility (NIF), yields are high enough and our neutron spectrometers accurate enough that we see finer details of the peak shape. For example, we can measure the shift of the peak due to the bulk motion of the plasma, and we see indications of non-thermal broadening, skew, and kurtosis of the peak caused by the variations of temperature and fluid velocity during burn. We can also distinguish spectral differences among several lines of sight. This paper will review the theory of fusion neutron line shape, show examples of non-Gaussian line shapes and directional variations in NIF data, and describe detailed spectral shapes we see in radiation-hydrodynamics simulations of implosions.

  10. The effect of baryons on redshift space distortions and cosmic density and velocity fields in the EAGLE simulation

    CERN Document Server

    Hellwing, Wojciech A; Frenk, Carlos S; Theuns, Tom; Schaye, Joop; Bower, Richard G; Crain, Robert A

    2016-01-01

    We use the EAGLE galaxy formation simulation to study the effects of baryons on the power spectrum of the total matter and dark matter distributions and on the velocity fields of dark matter and galaxies. On scales $k\\geq \\sim4{h\\,{\\rm Mpc}^{-1}}$ the effect of baryons on the amplitude of the total-matter power spectrum is greater than $1\\%$. The back-reaction of baryons affects the density field of the dark matter at the level of $\\sim3\\%$ on scales of $1\\leq k/({h\\,{\\rm Mpc}^{-1}})\\leq 5$. The dark matter velocity divergence power spectrum at $k\\leq \\sim0.5{h\\,{\\rm Mpc}^{-1}}$ is changed by less than $1\\%$. The 2D redshift-space power spectrum is affected at the level of $\\sim6\\%$ at $k_\\perp\\geq \\sim1{h\\,{\\rm Mpc}^{-1}}$, but for $k_\\perp\\leq 0.4{h\\,{\\rm Mpc}^{-1}}$ the amplitude differs by less than $1\\%$. We report vanishingly small baryonic velocity bias for haloes: the peculiar velocities of haloes with with $M_{200}>3\\times10^{11}{{\\rm M}_{\\odot}}$ (hosting galaxies with $M_{*}>10^9{{\\rm M}_{\\odot}}$)...

  11. A comparison between the patella and the calcaneus using ultrasound velocity and attenuation as predictors of bone mineral density

    Science.gov (United States)

    Han, S. M.; Davis, J.

    1997-10-01

    The bone mineral density (BMD), ultrasound velocity (UV) and attenuation were examined in sixteen matched sets of human patellae and calcanei. For the sixteen calcanei, BMD was strongly correlated with all ultrasound parameters. Calcaneal UV appeared to be inferior to attenuation in the ability to predict BMD. For the sixteen patellae, the average UV was found to be greater in the superior/inferior direction than in the anterior/posterior and medial/lateral directions. It was found that patella BMD was significantly correlated with each of three directional ultrasound velocities. The relationship between BMD and ultrasound attenuation parameters was not significant in the patella. A comparative study of the two different bone sets demonstrated that the BMDs of the patella and calcaneus were significantly correlated with each other. Ultrasound velocity of calcaneus, measured in the medial/lateral direction, was not significantly associated with any of three directional ultrasound velocities in the patella. Similarly, ultrasound attenuation parameters of calcaneus were not significantly correlated with those of patella. The present study also demonstrated evidence that when predicting BMDs at their respective sites using ultrasound, the calcaneus appeared to be superior to the patella.

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

    Science.gov (United States)

    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.

  13. The characteristics of the ion temperature and toroidal rotation velocity in the KSTAR plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Won Ha; Lee, Hyung Ho; Oh, Seung Tae [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Charge exchange spectroscopy (CES) is one of the important diagnostics on the Korea Superconducting Tokamak Advanced Research (KSTAR) to get ion temperature and toroidal rotation velocity. We describe the current status and the improvements made over the last two years. The current system upgraded from a Czerny-Turner spectrometer consists of two spectroscopic systems looking at the KSTAR neutral beam which is modulated 5 Hz for special period. One system has a DS spectrometer (f/2.8) lent from NIFS with pitch-controlled double slit fiber bundle with back- illuminated CCD and the other system has Kspectrometer (F/2.0) made by NFRI with intensified CCD. The K-spectrometer has a grating number of 2400 g/mm, focal length of 200 mm. The upgrade of two high throughput spectrometers enables to improve the time resolution from 200 msec to around 10 msec. This article focuses on improved edge spatial interval from increasing of plasma viewing channels to 5 mm and enhanced time resolution from a high throughput spectrometer with back-illuminated CCD. The upgrade has allowed to measure pedestal ion temperature and toroidal rotation velocity profiles in KSTAR H-mode

  14. Magnetic resonance flow velocity and temperature mapping of a shape memory polymer foam device

    Directory of Open Access Journals (Sweden)

    Wilson Thomas S

    2009-12-01

    Full Text Available Abstract Background Interventional medical devices based on thermally responsive shape memory polymer (SMP are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. Methods A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Results Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Conclusions Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  15. Potential, velocity, and density fields from redshift-distance samples: Application - Cosmography within 6000 kilometers per second

    Science.gov (United States)

    Bertschinger, Edmund; Dekel, Avishai; Faber, Sandra M.; Dressler, Alan; Burstein, David

    1990-01-01

    A potential flow reconstruction algorithm has been applied to the real universe to reconstruct the three-dimensional potential, velocity, and mass density fields smoothed on large scales. The results are shown as maps of these fields, revealing the three-dimensional structure within 6000 km/s distance from the Local Group. The dominant structure is an extended deep potential well in the Hydra-Centaurus region, stretching across the Galactic plane toward Pavo, broadly confirming the Great Attractor (GA) model of Lynden-Bell et al. (1988). The Local Supercluster appears to be an extended ridge on the near flank of the GA, proceeding through the Virgo Southern Extension to the Virgo and Ursa Major clusters. The Virgo cluster and the Local Group are both falling toward the bottom of the GA potential well with peculiar velocities of 658 + or - 121 km/s and 565 + or - 125 km/s, respectively.

  16. The Velocity and Density Distribution of Earth-Intersecting Meteoroids: Implications for Environment Models

    Science.gov (United States)

    Moorhead, A. V.; Brown, P. G.; Campbell-Brown, M. D.; Moser, D. E.; Blaauw, R. C.; Cooke, W. J.

    2017-01-01

    Meteoroids are known to damage spacecraft: they can crater or puncture components, disturb a spacecraft's attitude, and potentially create secondary electrical effects. Because the damage done depends on the speed, size, density, and direction of the impactor, accurate environment models are critical for mitigating meteoroid-related risks. Yet because meteoroid properties are derived from indirect observations such as meteors and impact craters, many characteristics of the meteoroid environment are uncertain. In this work, we present recent improvements to the meteoroid speed and density distributions. Our speed distribution is derived from observations made by the Canadian Meteor Orbit Radar. These observations are de-biased using modern descriptions of the ionization efficiency. Our approach yields a slower meteoroid population than previous analyses (see Fig. 1 for an example) and we compute the uncertainties associated with our derived distribution. We adopt a higher fidelity density distribution than that used by many older models. In our distribution, meteoroids with TJ less than 2 are assigned to a low-density population, while those with TJ greater than 2 have higher densities (see Fig. 2). This division and the distributions themselves are derived from the densities reported by Kikwaya et al. These changes have implications for the environment: for instance, the helion/antihelion sporadic sources have lower speeds than the apex and toroidal sources and originate from high-T(sub J) parent bodies. Our on-average slower and denser distributions thus imply that the helion and antihelion sources dominate the meteoroid environment even more completely than previously thought. Finally, for a given near-Earth meteoroid cratering rate, a slower meteoroid population produces a comparatively higher rate of satellite attitude disturbances.

  17. Pressure, density, temperature and entropy fluctuations in compressible turbulent plane channel flow

    CERN Document Server

    Gerolymos, G A

    2013-01-01

    We investigate the fluctuations of thermodynamic state-variables in compressible aerodynamic wall-turbulence, using results of direct numerical simulation (DNS) of compressible turbulent plane channel flow. The basic transport equations governing the behaviour of thermodynamic variables (density, pressure, temperature and entropy) are reviewed and used to derive the exact transport equations for the variances and fluxes (transport by the fluctuating velocity field) of the thermodynamic fluctuations. The scaling with Reynolds and Mach number of compressible turbulent plane channel flow is discussed. Correlation coefficients and higher-order statistics of the thermodynamic fluctuations are examined. Finally, detailed budgets of the transport equations for the variances and fluxes of the thermodynamic variables from a well-resolved DNS are analysed. Implications of these results both to the understanding of the thermodynamic interactions in compressible wall-turbulence and to possible improvements in statistical...

  18. Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    H. Park; E. Mazzucato; T. Munsat; C.W. Domier; M. Johnson; N.C. Luhmann, Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

    2004-05-07

    Diagnostic systems for fluctuation measurements in plasmas have, of necessity, evolved from simple 1-D systems to multi-dimensional systems due to the complexity of the MHD and turbulence physics of plasmas illustrated by advanced numerical simulations. Using the recent significant advancements in millimeter wave imaging technology, Microwave Imaging Reflectometry (MIR) and Electron Cyclotron Emission Imaging (ECEI), simultaneously measuring density and temperature fluctuations, are developed for TEXTOR. The MIR system was installed on TEXTOR and the first experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The new 2-D ECE Imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured a true 2-D images of Te fluctuations of m=1 oscillation (''sawteeth'') near the q {approx} 1 surface for the first time.

  19. The Evolution of Nuclear Multifragmentation in the Temperature-Density Plane

    CERN Document Server

    Warren, P G; Alexander, J M; Bieser, F; Brady, F P; Caccia, Z; Cebra, D A; Chacon, A D; Chance, J L; Choi, Y; Costa, S; Elliott, J B; Gilkes, M L; Hauger, J A; Hirsch, A S; Hjort, E L; Insolia, A; Justice, M; Keane, D; Kitner, J C; Lacey, R A; Lauret, J; Lindenstruth, V; Lisa, M A; Matis, H S; McGrath, R L; McMahan, M; McParland, C P; Müller, W F; Olson, D L; Partlan, M D; Porile, N T; Potenza, R; Rai, G; Rasmussen, J; Ritter, H G; Romanski, J; Romero, J L; Russo, G V; Sann, H; Scharenberg, R P; Scott, A; Shao, Y; Srivastava, B K; Symons, T J M; Tincknell, M L; Tuvé, C; Wang, S; Wieman, H H; Wienold, T; Wolf, K

    1996-01-01

    The mean transverse kinetic energies of the fragments formed in the interaction of 1 A GeV Au+C have been determined. An energy balance argument indicates the presence of a collective energy which increases in magnitude with increasing multiplicity and accounts for nearly half of the measured mean transverse kinetic energy. The radial flow velocity associated with the collective energy yields estimates for the time required to expand to the freeze-out volume. Isentropic trajectories in the temperature-density plane are shown for the expansion and indicate that the system goes through the critical region at the same multiplicities as deduced from a statistical analysis. Here, the expansion time is approximately 70 fm/c.

  20. Atmospheric density, temperature and wind measurement techniques during the 1980 Energy Budget Campaign

    Science.gov (United States)

    Schmidlin, F. J.; Philbrick, C. R.; Offermann, D.

    1981-01-01

    Super Loki rocketsonde systems are described. The datasonde telemeters data to a ground station where ambient temperatures are calculated between 20 and 70 km. The sphere is a passive, radar tracked system which allows density to be calculated between 30 and 90 km. When flown simultaneously the systems give redundant data in the altitudes between 30 and 70 km. The datasonde has a balloon parachute that descends more slowly than a conventional parachute and is more stable. Because of launch constraints the datasondes reached very high apogees, leading to very fast descent velocities. Aerodynamic heating reduced thermistor sensitivity. Anomalous parachute behavior influenced wind sensing until a denser layer was reached. The spheres collapsed above 60 km altitude, but their data, combined with dropsonde data give significant results for 21 flights. These show that the stratosphere is colder than Cospar 72 model predictions and the mesosphere is warmer.

  1. Mathematical modeling of velocity and number density profiles of particles across the flame propagation through a micro-iron dust cloud.

    Science.gov (United States)

    Bidabadi, Mehdi; Haghiri, Ali; Rahbari, Alireza

    2010-04-15

    In this study, an attempt has been made to analytically investigate the concentration and velocity profiles of particles across flame propagation through a micro-iron dust cloud. In the first step, Lagrangian particle equation of motion during upward flame propagation in a vertical duct is employed and then forces acting upon the particle, such as thermophoretic force (resulted from the temperature gradient), gravitation and buoyancy are introduced; and consequently, the velocity profile as a function of the distance from the leading edge of the combustion zone is extracted. In the resumption, a control volume above the leading edge of the combustion zone is considered and the change in the particle number density in this control volume is obtained via the balance of particle mass fluxes passing through it. This study explains that the particle concentration at the leading edge of the combustion zone is more than the particle agglomeration in a distance far from the flame front. This increase in the particle aggregation above the combustion zone has a remarkable effect on the lower flammability limits of combustible particle cloud. It is worth noticing that the velocity and particle concentration profiles show a reasonable compatibility with the experimental data.

  2. Turbulence induced collisional velocities and density enhancements: large inertial range results from shell models

    CERN Document Server

    Hubbard, Alexander

    2012-01-01

    To understand the earliest stages of planet formation, it is crucial to be able to predict the rate and the outcome of dust grains collisions, be it sticking and growth, bouncing, or fragmentation. The outcome of such collisions depends on the collision speed, so we need a solid understanding of the rate and velocity distribution of turbulence-induced dust grain collisions. The rate of the collisions depends both on the speed of the collisions and the degree of clustering experienced by the dust grains, which is a known outcome of turbulence. We evolve the motion of dust grains in simulated turbulence, an approach that allows a large turbulent inertial range making it possible to investigate the effect of turbulence on meso-scale grains (millimeter and centimeter). We find three populations of dust grains: one highly clustered, cold and collisionless; one warm; and the third "hot". Our results can be fit by a simple formula, and predict both significantly slower typical collisional velocities for a given turb...

  3. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    Science.gov (United States)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  4. The effect of baryons on redshift space distortions and cosmic density and velocity fields in the EAGLE simulation

    Science.gov (United States)

    Hellwing, Wojciech A.; Schaller, Matthieu; Frenk, Carlos S.; Theuns, Tom; Schaye, Joop; Bower, Richard G.; Crain, Robert A.

    2016-09-01

    We use the Evolution and Assembly of GaLaxies and their Environments (EAGLE) galaxy formation simulation to study the effects of baryons on the power spectrum of the total matter and dark matter distributions and on the velocity fields of dark matter and galaxies. On scales k ≳ 4 h Mpc-1 the effect of baryons on the amplitude of the total matter power spectrum is greater than 1 per cent. The back-reaction of baryons affects the density field of the dark matter at the level of ˜3 per cent on scales of 1 ≤ k/( h Mpc-1) ≤ 5. The dark matter velocity divergence power spectrum at k ≲ 0.5 h Mpc-1 is changed by less than 1 per cent. The 2D redshift space power spectrum is affected at the level of ˜6 per cent at |k|≳ 1 h Mpc^{-1} (for μ > 0.5), but for |k|≤ 0.4 h Mpc^{-1} it differs by less than 1 per cent. We report vanishingly small baryonic velocity bias for haloes: the peculiar velocities of haloes with M200 > 3 × 1011 M⊙ (hosting galaxies with M* > 109 M⊙) are affected at the level of at most 1 km s-1, which is negligible for 1 per cent-precision cosmology. We caution that since EAGLE overestimates cluster gas fractions it may also underestimate the impact of baryons, particularly for the total matter power spectrum. Nevertheless, our findings suggest that for theoretical modelling of redshift space distortions and galaxy velocity-based statistics, baryons and their back-reaction can be safely ignored at the current level of observational accuracy. However, we confirm that the modelling of the total matter power spectrum in weak lensing studies needs to include realistic galaxy formation physics in order to achieve the accuracy required in the precision cosmology era.

  5. Comprehensive observation and modeling of earthquake and temperature-related seismic velocity changes in northern Chile with passive image interferometry

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-06-01

    We report on earthquake and temperature-related velocity changes in high-frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short-term velocity drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long-term velocity decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface-induced changes. Due to this high sensitivity, we observe a velocity response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of velocity drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual velocity changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic velocity with annual and daily periods indicate an atmospheric origin of the velocity changes that we confirm with a model based on thermally induced stress. This comprehensive model explains the lag time dependence of the temperature-related seismic velocity changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and velocity change, plus autocorrelation sensitivity kernels.

  6. SOME COLLISION PROCESSES IN PLASMAS WITH HIGHER TEMPERATURE AND DENSITY

    Institute of Scientific and Technical Information of China (English)

    KazuoTakayanagi

    1990-01-01

    Some collision processes important in hot and dense plasmas are discussed.Recent calculation of secondary electron velocity distribution in ionizing collision between an electron and a multiply-charged ion is reported.

  7. Measurement of inflight shell areal density perturbations in NIF capsule implosions near peak velocity

    Science.gov (United States)

    Hammel, B. A.; Pickworth, L.; Smalyuk, V.; Macphee, A.; Scott, H. A.; Robey, H.; Barrios, M.; Regan, S. P.

    2015-11-01

    Quantitative measurements of shell-RhoR perturbations in capsules near peak implosion velocity (PV) are challenging. An external backlighter samples both sides of the shell, unless a re-entrant cone is used (potentially perturbing implosion). Emission from the hot core, after shock-stagnation and prior to PV, has been used as a self-backlighter, providing a means to sample one side of the capsule. Adding high-Z gas (~ 1% Ar) to the capsule fill in Symcaps (4He), has produced a continuum backlighter with significant increase in emission at photon energies ~ 8 keV over nominal fills. From images of the transmitted self-emission, above and below the K-edge of an internally doped Cu layer, we infer the growth at PV of imposed perturbations (100 nm amplitude, mode 40). Prepared by LLNL under Contract DE-AC52-07NA27344.

  8. Temperature Coefficient of Sound Velocity of Perovskite-Enstatite and Lateral Thermal Heterogeneity in Earth's Lower Mantle

    Institute of Scientific and Technical Information of China (English)

    GONG Zi-Zheng; XIE Hong-Sen; JING Fu-Qian; LIU Yong-Gang; GUO Jie; XU Jian

    2000-01-01

    Using the differences of sound velocity and temperature on the Hugoniot and isoentropic state, the temperature coefficients of sound velocity of perovskite-enstatite under high pressure were obtained. For compressional, shear and bulk wave velocities, their temperature coefficients decrease from 0.386, 0.251, 0.255m/(s.K) at 40GPa to 0.197, 0.131, 0. 162m/(s.K) at 140GPa, respectively. Extrapolating these to zero pressure results in ( K/ T)0 =-0.0279 GPa. K-1, which is consistent very well with the value got by hydrostatic pressure experiment. On the basis of our data, we conclude that the compressional wave velocity anomaly of 0.1-0.2% in the deep lower mantle and 2% in the D" region would imply lateral thermal heterogeneity with amplitude of 53-106 K and 1066 K in these regions, respectively.

  9. Ultramassive dense early-type galaxies: velocity dispersions and number density evolution since z=1.6

    CERN Document Server

    Gargiulo, A; Tamburri, S; Lonoce, I; Ciocca, F

    2016-01-01

    In this paper we investigate the mass assembly history of ultramassive (Mstar > 10^11Msun) dense (Sigma = Mstar/(2*pi*Re^2) > 2500 Msun/pc^2) early-type galaxies (ETGs) over the last 9 Gyr. We have traced the evolution of the number density rho of ultramassive dense ETGs and have compared their structural (effective radius Re and stellar mass Mstar) and dynamical (velocity dispersion sigma_e) parameters over the redshift range 0 = 1.4, or that, if a significant fraction of them evolves in size, new ultramassive dense ETGs must form at z < 1.5 to maintain their number density almost constant. The difficulty into identify good progenitors for these new dense ETGs at z < 1.5, and the stellar populations properties of local ultramassive dense ETGs point toward the first hypothesis.

  10. Non-Maxwellian velocity distribution functions associated with steep temperature gradients in the solar transition region. Paper 1: Estimate of the electron velocity distribution functions

    Science.gov (United States)

    Roussel-Dupre, R.

    1979-01-01

    It was shown that, in the presence of the steep temperature gradients characteristic of EUV models of the solar transition region, the electron and proton velocity distribution functions are non-Maxwellian and are characterized by high energy tails. The magnitude of these tails are estimated for a model of the transition region and the heat flux is calculated at a maximum of 30 percent greater than predicted by collision-dominated theory.

  11. Ejecta velocity distribution of impact craters formed on quartz sand: Effect of projectile density on crater scaling law

    Science.gov (United States)

    Tsujido, Sayaka; Arakawa, Masahiko; Suzuki, Ayako I.; Yasui, Minami

    2015-12-01

    In order to clarify the effects of projectile density on ejecta velocity distributions for a granular target, impact cratering experiments on a quartz sand target were conducted by using eight types of projectiles with different densities ranging from 11 g cm-3 to 1.1 g cm-3, which were launched at about 200 m s-1 from a vertical gas gun at Kobe University. The scaling law of crater size, the ejection angle of ejecta grains, and the angle of the ejecta curtain were also investigated. The ejecta velocity distribution obtained from each projectile was well described by the π-scaling theory of v0/√{gR} =k2(x0/R)-1/μ, where v0, g, R and x0 are the ejection velocity, gravitational acceleration, crater radius and ejection position, respectively, and k2 and μ are constants mostly depending on target material properties (Housen, K.R., Holsapple, K.A. [2011]. Icarus 211, 856-875). The value of k2 was found to be almost constant at 0.7 for all projectiles except for the nylon projectile, while μ increased with the projectile density, from 0.43 for the low-density projectile to 0.6-0.7 for the high-density projectile. On the other hand, the π-scaling theory for crater size gave a μ value of 0.57, which was close to the average of the μ values obtained from ejecta velocity distributions. The ejection angle, θ, of each grain decreased slightly with distance, from higher than 45° near the impact point to 30-40° at 0.6 R. The ejecta curtain angle is controlled by the two elementary processes of ejecta velocity distribution and ejection angle; it gradually increased from 52° to 63° with the increase of the projectile density. The comparison of our experimental results with the theoretical model of the crater excavation flow known as the Z-model revealed that the relationship between μ and θ obtained by our experiments could not be described by the Z-model (Maxwell, D.E. [1977]. In: Roddy, D.J., Pepin, R.O., Merrill, R.B. (Eds.), Impact and Explosion Cratering

  12. The XMM Cluster Survey: evolution of the velocity dispersion -- temperature relation over half a Hubble time

    CERN Document Server

    Wilson, Susan; Rooney, Philip J; Caldwell, Caroline; Kay, Scott T; Collins, Chris A; McCarthy, Ian G; Romer, A Kathy; Bermeo-Hernandez, Alberto; Bernstein, Rebecca; da Costa, Luiz; Gifford, Daniel; Hollowood, Devon; Hoyle, Ben; Jeltema, Tesla; Liddle, Andrew R; Maia, Marcio A G; Mann, Robert G; Mayers, Julian A; Mehrtens, Nicola; Miller, Christopher J; Nichol, Robert C; Ogando, Ricardo; Sahlén, Martin; Stahl, Benjamin; Stott, John P; Thomas, Peter A; Viana, Pedro T P; Wilcox, Harry

    2015-01-01

    We measure the evolution of the velocity dispersion--temperature ($\\sigma_{\\rm v}$--$T_{\\rm X}$) relation up to $z = 1$ using a sample of 38 galaxy clusters drawn from the \\textit{XMM} Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 $z > 0.5$ clusters observed with the GMOS instruments on the Gemini telescopes. Using an orthogonal regression method, we find that the slope of the relation is steeper than that expected if clusters were self-similar, and that the evolution of the normalisation is slightly negative, but not significantly different from zero ($\\sigma_{\\rm v} \\propto T^{0.86 \\pm 0.14} E(z)^{-0.37 \\pm 0.33}$). We verify our results by applying our methods to cosmological hydrodynamical simulations. The lack of evolution seen from the data suggests that the feedback does not significantly heat the gas, a result that...

  13. Density of Liquid Steel over Temperature Range of 1 803-1 873 K

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang

    2004-01-01

    The density of three kinds of liquid steel was measured by a modified sessile drop method over the temperature range of 1 803-1 873 K. It is found that the density of liquid steels decreases with increasing temperature and carbon content in steel. Both of the density and its absolute temperature coefficient of studied steels are smaller than the literature values of pure iron. The molar volume of the steels increases with increasing temperature.

  14. Long-time behavior of the velocity autocorrelation function at low densities and near the critical point of simple fluids.

    Science.gov (United States)

    Dib, R F A; Ould-Kaddour, F; Levesque, D

    2006-07-01

    Numerous theoretical and numerical works have been devoted to the study of the algebraic decrease at large times of the velocity autocorrelation function of particles in a fluid. The derivation of this behavior, the so-called long-time tail, generally based on linearized hydrodynamics, makes no reference to any specific characteristic of the particle interactions. However, in the literature doubts have been expressed about the possibility that by numerical simulations the long-time tail can be observed in the whole fluid phase domain of systems in which the particles interact by soft-core and attractive pair potentials. In this work, extensive and accurate molecular-dynamics simulations establish that the predicted long-time tail of the velocity autocorrelation function exists in a low-density fluid of particles interacting by a soft-repulsive potential and near the liquid-gas critical point of a Lennard-Jones system. These results contribute to the confirmation that the algebraic decay of the velocity autocorrelation function is universal in these fluid systems.

  15. A Regime Diagram for Autoignition of Homogeneous Reactant Mixtures with Turbulent Velocity and Temperature Fluctuations

    KAUST Repository

    Im, Hong G.

    2015-04-02

    A theoretical scaling analysis is conducted to propose a diagram to predict weak and strong ignition regimes for a compositionally homogeneous reactant mixture with turbulent velocity and temperature fluctuations. The diagram provides guidance on expected ignition behavior based on the thermo-chemical properties of the mixture and the flow/scalar field conditions. The analysis is an extension of the original Zeldovich’s analysis by combining the turbulent flow and scalar characteristics in terms of the characteristic Damköhler and Reynolds numbers of the system, thereby providing unified and comprehensive understanding of the physical and chemical mechanisms controlling ignition characteristics. Estimated parameters for existing experimental measurements in a rapid compression facility show that the regime diagram predicts the observed ignition characteristics with good fidelity.

  16. SIMULATION TOOL OF VELOCITY AND TEMPERATURE PROFILES IN THE ACCELERATED COOLING PROCESS OF HEAVY PLATES

    Directory of Open Access Journals (Sweden)

    Antônio Adel dos Santos

    2014-10-01

    Full Text Available The aim of this paper was to develop and apply mathematical models for determining the velocity and temperature profiles of heavy plates processed by accelerated cooling at Usiminas’ Plate Mill in Ipatinga. The development was based on the mathematical/numerical representation of physical phenomena occurring in the processing line. Production data from 3334 plates processed in the Plate Mill were used for validating the models. A user-friendly simulation tool was developed within the Visual Basic framework, taking into account all steel grades produced, the configuration parameters of the production line and these models. With the aid of this tool the thermal profile through the plate thickness for any steel grade and dimensions can be generated, which allows the tuning of online process control models. The simulation tool has been very useful for the development of new steel grades, since the process variables can be related to the thermal profile, which affects the mechanical properties of the steels.

  17. Temperature Field-Wind Velocity Field Optimum Control of Greenhouse Environment Based on CFD Model

    Directory of Open Access Journals (Sweden)

    Yongbo Li

    2014-01-01

    Full Text Available The computational fluid dynamics technology is applied as the environmental control model, which can include the greenhouse space. Basic environmental factors are set to be the control objects, the field information is achieved via the division of layers by height, and numerical characteristics of each layer are used to describe the field information. Under the natural ventilation condition, real-time requirements, energy consumption, and distribution difference are selected as index functions. The optimization algorithm of adaptive simulated annealing is used to obtain optimal control outputs. A comparison with full-open ventilation shows that the whole index can be reduced at 44.21% and found that a certain mutual exclusiveness exists between the temperature and velocity field in the optimal course. All the results indicate that the application of CFD model has great advantages to improve the control accuracy of greenhouse.

  18. P-wave velocities of main upper mantle minerals at high temperature and high pressure and its geological implication

    Institute of Scientific and Technical Information of China (English)

    宋茂双; 谢鸿森; 郑海飞; 徐有生; 郭捷; 许祖鸣

    1996-01-01

    At 0 - 5.0GPa and room temperature to 1400℃, the P-wave velocities of olivine, clinopyroxene and orthopyroxene, which are three common minerals from upper mantle, are measured under both simulated oceanic and continental geothermal gradients. The experimental results indicate that the P-wave velocities of these minerals increase with depth under both geothermal gradients. This implicates that pressure is more important than temperature in deep earth in controlling the P-wave velocities of mantle minerals, but the increase of temperature has greater effect on P-wave velocities of main mantle minerals at greater depth than at smaller depth. At low pressure, the measured P-wave velocities of mantle minerals are smaller than their true values due to fracturing, compaction process and recrystallization of mineral powder. The true P-wave velocities of mantle minerals can be obtained at lower pressure by the extrapolation of measured velocities at a high pressure. At higher depth, all these three minerals sho

  19. P-wave velocity and density structure beneath Mt. Vesuvius: a magma body in the upper edifice?

    Directory of Open Access Journals (Sweden)

    Paolo Capuano

    2013-11-01

    Full Text Available A high-resolution image of the compressional wave velocity and density structure in the shallow edifice of Mount Vesuvius has been derived from simultaneous inversion of travel times and hypocentral parameters of local earthquakes and from gravity inversion. The robustness of the tomography solution has been improved by adding to the earthquake data a set of land based shots, used for constraining the travel time residuals. The results give a high resolution image of the P-wave velocity structure with details down to 300-500 m. The relocated local seismicity appears to extend down to 5 km depth below the central crater, distributed into two clusters, and separated by an anomalously high Vp region positioned at around 1 km depth. A zone with high Vp/Vs ratio in the upper layers is interpreted as produced by the presence of intense fluid circulation alternatively to the interpretation in terms of a small magma chamber inferred by petrologic studies. In this shallower zone the seismicity has the minimum energy, whilst most of the high-energy quakes (up to Magnitude 3.6 occur in the cluster located at greater depth. The seismicity appears to be located along almost vertical cracks, delimited by a high velocity body located along past intrusive body, corresponding to remnants of Mt. Somma. In this framework a gravity data inversion has been performed to study the shallower part of the volcano. Gravity data have been inverted using a method suitable for the application to scattered data in presence of relevant topography based on a discretization of the investigated medium performed by establishing an approximation of the topography by a triangular mesh. The tomography results, the retrieved density distribution, and the pattern of relocated seismicity exclude the presence of significant shallow magma reservoirs close to the central conduit. These should be located at depth higher than that of the base of the hypocenter volume, as evidenced by

  20. Visualizing density perturbations in the capsule shell in NIF implosions near peak velocity

    Science.gov (United States)

    Pickworth, L. A.; Hammel, B. A.; Smalyuk, V. A.; Macphee, A.; Scott, H. A.; Robey, H. F.; Field, J.; Barrios, M.; Regan, S. P.

    2016-10-01

    Engineering features on the capsule (surface roughness, support structures, etc.) can introduce outer surface perturbations that are ultimately detrimental to the performance of the capsule. Recent experiments have assessed minimal support structures and alternate pulse shapes using a re-entrant cone and back lighter that is perturbing to the implosion below radii of 500 μ m. Emission from the hot core, after shock-stagnation and prior to peak velocity (PV), has been used as a self-backlighter, providing a means to sample one side of the capsule at smaller radii. Adding high-Z gas ( 1 % Ar) to the capsule fill in Symcaps (4He), has produced a continuum backlighter with significant increase in emission at hv 8 keV over nominal fills. High-resolution imaging diagnostics with photon energy selectivity form 2D images of the transmitted self-emission, above and below the K-edge of an internally doped Cu layer. We can infer from these images the growth at PV of outer surface perturbations. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-697620.

  1. Temperature, velocity and species profile measurements for reburning in a pulverized, entrained flow, coal combustor

    Energy Technology Data Exchange (ETDEWEB)

    Tree, D.R.

    1999-03-01

    Nitrogen oxide emissions from pulverized coal combustion have been and will continue to be a regulated pollutant for electric utility boilers burning pulverized coal. Full scale combustion models can help in the design of new boilers and boiler retrofits which meet emissions standards, but these models require validation before they can be used with confidence. The objective of this work was to obtain detailed combustion measurements of pulverized coal flames which implement two NO reduction strategies, namely reburning and advanced reburning, to provide data for model validation. The data were also compared to an existing comprehensive pulverized coal combustion model with a reduced mechanism for NO reduction under reburning and advanced reburning conditions. The data were obtained in a 0.2 MW, cylindrical, down-fired, variable swirl, pulverized coal reactor. The reactor had a diameter of 0.76 m and a length of 2.4 m with access ports along the axial length. A Wyodak, sub-bituminous coal was used in all of the measurements. The burner had a centrally located primary fuel and air tube surrounded by heated and variably swirled secondary air. Species of NO, NO{sub x}, CO, CO{sub 2} and O{sub 2} were measured continuously. Aqueous sampling was used to measure HCN and NH{sub 3} at specific reactor locations. Samples were drawn from the reactor using water quenched suction probes. Velocity measurements were obtained using two component laser doppler anemometry in back-scatter mode. Temperature measurements were obtained using a shielded suction pyrometer. A series of six or more radial measurements at six or more axial locations within the reactor provided a map of species, temperature, and velocity measurements. In total, seven reactor maps were obtained. Three maps were obtained at baseline conditions of 0, 0.5 and 1.5 swirl and 10% excess air. Two maps were obtained under reburning conditions of 0.78 stoichiometric ratio and 1.5 swirl and 0.9 stoichiometric ratio and

  2. Temperature and Population Density Effects on Locomotor Activity of Musca domestica (Diptera: Muscidae)

    DEFF Research Database (Denmark)

    Schou, T. M.; Faurby, S.; Kjærsgaard, A.

    2013-01-01

    activity was measured for both sexes and at four densities (with mixed sexes) during a full light and dark (L:D) cycle at temperatures ranging from 10 to 40°C. Locomotor activity during daytime increased with temperature at all densities until reaching 30°C and then decreased. High-density treatments...

  3. Analysis of contributions of nonlinear material constants to temperature-induced velocity shifts of quartz surface acoustic wave resonators.

    Science.gov (United States)

    Zhang, Haifeng; Kosinski, John A; Zuo, Lei

    2016-09-01

    In this paper, we examine the significance of the various higher-order effects regarding calculating temperature behavior from a set of material constants and their temperature coefficients. Temperature-induced velocity shifts have been calculated for quartz surface acoustic wave (SAW) resonators and the contributions of different groups of nonlinear material constants (third-order elastic constants (TOE), third-order piezoelectric constants (TOP), third-order dielectric constants (TOD) and electrostrictive constants (EL)) to the temperature-induced velocity shifts have been analyzed. The analytical methodology has been verified through the comparison of experimental and analytical results for quartz resonators. In general, the third-order elastic constants were found to contribute most significantly to the temperature-induced shifts in the SAW velocity. The contributions from the third-order dielectric constants and electrostrictive constants were found to be negligible. For some specific cases, the third-order piezoelectric constants were found to make a significant contribution to the temperature-induced shifts. The significance of each third-order elastic constant as a contributor to the temperature-velocity effect was analyzed by applying a 10% variation to each of the third-order elastic constants separately. Additionally, we have considered the issues arising from the commonly used thermoelastic expansions that provide a good but not exact description of the temperature effects on frequency in piezoelectric resonators as these commonly used expansions do not include the effects of higher-order material constants.

  4. Experiment to measure oxygen opacity at high density and temperature

    Science.gov (United States)

    Keiter, Paul; Mussack, Katie; Orban, Chris; Colgan, James; Ducret, Jean-Eric; Fontes, Christopher J.; Guzik, Joyce Ann; Heeter, Robert F.; Kilcrease, Dave; Le Pennec, Maelle; Mancini, Roberto; Perry, Ted; Turck-Chièze, Sylvaine; Trantham, Matt

    2017-06-01

    In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. This discrepancy has led to an investigation of opacities through laboratory experiments and improved opacity models for many of the larger contributors to the sun’s opacity, including iron and oxygen. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al, 2015]. Although these results are still controversial, repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for C, O and Fe to address the solar abundance issue [Colgan, 2013]. Armstrong et al [2014] have also implemented changes in the ATOMIC code for low-Z elements. However, no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions.This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, grant No. DE-NA0001840, and the NLUF Program, grant No. DE-NA0000850, and through LLE, University of Rochester by the NNSA/OICF under Agreement No. DE-FC52-08NA28302.

  5. Large-strain time-temperature equivalence in high density polyethylene for prediction of extreme deformation and damage

    Directory of Open Access Journals (Sweden)

    Gray G.T.

    2012-08-01

    Full Text Available Time-temperature equivalence is a widely recognized property of many time-dependent material systems, where there is a clear predictive link relating the deformation response at a nominal temperature and a high strain-rate to an equivalent response at a depressed temperature and nominal strain-rate. It has been found that high-density polyethylene (HDPE obeys a linear empirical formulation relating test temperature and strain-rate. This observation was extended to continuous stress-strain curves, such that material response measured in a load frame at large strains and low strain-rates (at depressed temperatures could be translated into a temperature-dependent response at high strain-rates and validated against Taylor impact results. Time-temperature equivalence was used in conjuction with jump-rate compression tests to investigate isothermal response at high strain-rate while exluding adiabatic heating. The validated constitutive response was then applied to the analysis of Dynamic-Tensile-Extrusion of HDPE, a tensile analog to Taylor impact developed at LANL. The Dyn-Ten-Ext test results and FEA found that HDPE deformed smoothly after exiting the die, and after substantial drawing appeared to undergo a pressure-dependent shear damage mechanism at intermediate velocities, while it fragmented at high velocities. Dynamic-Tensile-Extrusion, properly coupled with a validated constitutive model, can successfully probe extreme tensile deformation and damage of polymers.

  6. Impact of temperature-velocity distribution on fusion neutron peak shape

    Science.gov (United States)

    Munro, David

    2016-10-01

    Doppler broadening of the 14 MeV DT and 2.45 MeV DD fusion neutron lines has long been our best measure of temperature in a burning plasma. At the National Ignition Facility yields are high enough and our neutron spectrometers accurate enough that we see finer details of the peak shape. For example, we can measure the shift of the peak due to bulk motion of the plasma, and we see indications of non-thermal broadening, skew, and kurtosis of the peak caused by the variations of temperature and fluid velocity during burn. We can also distinguish spectral differences among several lines of sight. This talk will review the theory of fusion neutron line shape, show examples of non-Gaussian line shapes and directional variations in NIF data, and describe detailed spectral shapes we see in radhydro implosion simulations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  7. On the temperature and velocity through the photosphere of a sunspot penumbra

    Science.gov (United States)

    del Toro Iniesta, J. C.; Tarbell, T. D.; Ruiz Cobo, B.

    1994-11-01

    We investigate the structure in depth of a sunspot penumbra by means of the inversion code of the radiative transfer equation proposed by Ruiz Cobo & del Toro Iniesta (1992), applied to a set of filtergrams of a sunspot, scanning the Fe I line at 5576.1 A, with a sampling interval of 30 mA, from -120 to 120 mA from line center (data previously analyzed by Title et al. 1993). The temperature structure of this penumbra is obtained for each of the 801 pixels selected (0.32 sec x 0.32 sec). On the average, the temperatures seem to decrease as we move inward, but the differences are of the order of the rms values (approximately equal 100-200 K) at a given distance to sunspot center. The outer parts of the penumbra have also a bigger curvature in the T versus log tau5 relation than the inner parts. We realize, however, that these differences might be influenced by possible stray light effects. Compared to the quiet Sun, penumbral temperatures are cooler at deep layers and hotter at high layers. A mean penumbral model atmosphere is presented. The asymmetries observed in the intensity profile (the line is magnetically insensitive) are deduced to be produced by strong gradients of the line-of-sight velocity that sharply vary spatially along slices of almost constant distance to sunspot center. These variations suggest that such gradients are not only needed to explain the broadband circular polarization observed in sunspots (see Sanchez Almeida & Lites 1992) but are a main characteristic of the fine-scale penumbra. The results are compatible with an Evershed flow present everywhere, but its gradient with depth turns out to vary so that the flow seems to be mainly concentrated in some penumbral fibrils when studied through Dopplergrams. Finally, as by-products of this study, we put constraints to the practical usefulness of the Eddington-Barbier relation, and we explain the values of the Fourier Dopplergrams to be carrying information of layers around the centroid of the

  8. Effects of Re-heating Tissue Samples to Core Body Temperature on High-Velocity Ballistic Projectile-tissue Interactions.

    Science.gov (United States)

    Humphrey, Caitlin; Henneberg, Maciej; Wachsberger, Christian; Maiden, Nicholas; Kumaratilake, Jaliya

    2017-02-23

    Damage produced by high-speed projectiles on organic tissue will depend on the physical properties of the tissues. Conditioning organic tissue samples to human core body temperature (37°C) prior to conducting ballistic experiments enables their behavior to closely mimic that of living tissues. To minimize autolytic changes after death, the tissues are refrigerated soon after their removal from the body and re-heated to 37°C prior to testing. This research investigates whether heating 50-mm-cube samples of porcine liver, kidney, and heart to 37°C for varying durations (maximum 7 h) can affect the penetration response of a high-speed, steel sphere projectile. Longer conditioning times for heart and liver resulted in a slight loss of velocity/energy of the projectile, but the reverse effect occurred for the kidney. Possible reasons for these trends include autolytic changes causing softening (heart and liver) and dehydration causing an increase in density (kidney).

  9. Measurement of solar wind electron density and temperature in the shocked region of Venus and the density and temperature of photoelectrons within the ionosphere of Venus

    Science.gov (United States)

    Knudsen, William C.; Jones, Douglas E.; Peterson, Bryan G.; Knadler, Charles E.

    2016-08-01

    Presented herein are measurements of the solar wind electron number density and temperature near and within the bow shock of Venus. The measurements were made by the Pioneer Venus mission Orbiter Retarding Potential Analyzer operating in its suprathermal electron mode. The measurements are essentially point measurements. The spacecraft travels approximately 0.8 km during the 0.1 s time interval required to record a single I-V curve. The dual measurement of a density and temperature is obtained from one sweep by least squares fitting a mathematical Maxwellian expression to the I-V curve. The distance between successive measurements is approximately 100 km. In many orbits, when the spacecraft is crossing or traveling within the bow shock, the derived densities and temperatures (high density, high temperature (HDHT)) are large, densities of the order of 100 cm-3 and temperatures of the order of several hundred eV. We interpret these HDHT measurements as measurements in regions where the large, directed kinetic energy of the solar wind ions is being degraded into randomized, more thermal-like energy distributions of the electrons and ions through wave-particle interactions. The HDHT values define the electron energy distribution in the limited energy interval 0 to 50 eV. We assume that the underlying electron flux distributions are flat topped like those measured in the Earth's bow shock. We also report densities and temperatures of EUV produced photoelectron energy distributions measured within the ionosphere.

  10. Molecular dynamics simulation for baryon-quark phase transition at finite temperature and density

    CERN Document Server

    Akimura, Y; Yoshinaga, N; Chiba, S; Akimura, Yuka; Maruyama, Toshiki; Yoshinaga, Naotaka; Chiba, Satoshi

    2005-01-01

    We study the baryon-quark phase transition in a molecular dynamics (MD) of quark degrees of freedom at finite temperature and density. The baryon state at low density and temperature, and the deconfined quark state at high density and temperature are reproduced. We investigate the equations of state of matters with different $u$-$d$-$s$ compositions. Then we draw phase diagrams in the temperature-density plane by this simulation. It is found that the baryon-quark transition is sensitive to the quark width.

  11. Impact of Velocity Slip and Temperature Jump of Nanofluid in the Flow over a Stretching Sheet with Variable Thickness

    Science.gov (United States)

    Guo, Chengjie; Zheng, Liancun; Zhang, Chaoli; Chen, Xuehui; Zhang, Xinxin

    2016-05-01

    In this study, the generalised velocity slip and the generalised temperature jump of nanofluid in the flow over a stretching sheet with variable thickness are investigated. Because of the non-adherence of the fluid to a solid boundary, the velocity slip and the temperature jump between fluid and moving sheet may happen in industrial process, so taking velocity slip and temperature jump into account is indispensable. It is worth mentioning that the analysis of the velocity v, which has not been seen in the previous references related to the variable thickness sheet, is presented. The thermophoresis and the Brownian motion, which are the two very important physical parameters, are fully studied. The governing equations are simplified into ordinary differential equations by the proper transformations. The homotopy analysis method (HAM) is applied to solve the reduced equations for general conditions. In addition, the effects of involved parameters such as velocity slip parameter, temperature jump parameter, Prandtl number, magnetic field parameter, permeable parameter, Lewis number, thermophoresis parameter, and Brownian motion parameter are investigated and analysed graphically.

  12. Phonon Density of States and Sound Velocities of Magnesiow?stite in Earth's Lower Mantle

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J; Jacosben, S D; Sturhahn, W; Jackson, J; Zhao, J; Yoo, C

    2006-01-20

    The partial phonon densities of states of iron in magnesiowuestite [(Mg{sub 0.75},Fe{sub 0.25})O] have been measured by nuclear inelastic X-ray scattering up to 109 GPa. Compressional and shear wave velocities, shear moduli, and their pressure derivatives increase significantly across the spin-pairing transition of iron in (Mg{sub 0.75},Fe{sub 0.25})O at approximately 50 GPa. The effects of the transition on the elastic properties of (Mg,Fe)O at lower-mantle pressures are in contrast to what was predicted by studying MgO and high-spin magnesiowuestite, and need to be considered in future geophysical modeling of the lower mantle. The transition also affects other thermodynamic properties of magnesiowuestite under high pressures.

  13. Temperature and velocity field of the two-dimensional transverse hot-air jet in a freestream flow.

    Science.gov (United States)

    Tatom, J. W.; Cooper, M. A.; Hayden, T. K.

    1972-01-01

    Experimental investigation of the low subsonic, two-dimensional transverse hot-air jet. In the study jet-to-freestream angles of 90, 120, 135, and 150 deg and jet-to-freestream velocity ratios of 5, 10, and 20 were investigated. In the tests the jet velocity and temperature fields were measured using a temperature-compensated hot-wire anemometer. Photographs of the flowfield were also made. The tests results are compared with the available data and analysis. Results indicate a relatively minor deflection of the freestream by the jet and the presence of a large separated flow region behind the jet.

  14. Charged impurity scattering limited low temperature resistivity of low density silicon inversion layers

    OpenAIRE

    Sarma, S. Das; Hwang, E. H.

    1998-01-01

    We calculate within the Boltzmann equation approach the charged impurity scattering limited low temperature electronic resistivity of low density $n$-type inversion layers in Si MOSFET structures. We find a rather sharp quantum to classical crossover in the transport behavior in the $0 - 5$K temperature range, with the low density, low temperature mobility showing a strikingly strong non-monotonic temperature dependence, which may qualitatively explain the recently observed anomalously strong...

  15. Extracting kinetic freeze-out temperature and radial flow velocity from an improved Tsallis distribution

    CERN Document Server

    Lao, Hai-Ling; Lacey, Roy A

    2016-01-01

    We analyze the transverse momentum ($p_T$) spectra of identified particles ($\\pi^{\\pm}$, $K^{\\pm}$, $p$, and $\\bar p$) produced in gold-gold (Au-Au) and lead-lead (Pb-Pb) collisions over a $\\sqrt{s_{NN}}$ (center-of-mass energy per nucleon pair) range from 14.5 GeV [one of the Relativistic Heavy Ion Collider (RHIC) energies] to 2.76 TeV [one of the Large Hadron Collider (LHC) energies]. For the spectra with a narrow $p_T$ range, an improved Tsallis distribution which is in fact the Tsallis distribution with radial flow is used. For the spectra with a wide $p_T$ range, a superposition of the improved Tsallis distribution and an inverse power-law is used. Both the extracted kinetic freeze-out temperature ($T_0$) and radial flow velocity ($\\beta_T$) increase with the increase of $\\sqrt{s_{NN}}$, which indicate a higher excitation and larger expansion of the interesting system at the LHC. Both the values of $T_0$ and $\\beta_T$ in central collisions are slightly larger than those in peripheral collisions, and they...

  16. Velocity, temperature and normal force dependence on friction: An analytical and molecular dynamic study

    CERN Document Server

    Dias, R A; Rapini, M; Costa, B V

    2007-01-01

    In this work we propose an extension to the analytical one-dimensional model proposed by E. Gnecco (Phys. Rev. Lett. 84:1172) to describe friction. Our model includes normal forces and the dependence with the angular direction of movement in which the object is dragged over a surface. The presence of the normal force in the model allow us to define judiciously the friction coefficient, instead of introducing it as an {\\sl a posteriori} concept. We compare the analytical results with molecular dynamics simulations. The simulated model corresponds to a tip sliding over a surface. The tip is simulated as a single particle interacting with a surface through a Lennard-Jones $(6-12)$ potential. The surface is considered as consisting of a regular BCC(001) arrangement of particles interacting with each other through a Lennard-Jones $(6-12)$ potential. We investigate the system under several conditions of velocity, temperature and normal forces. Our analytical results are in very good agreement with those obtained by...

  17. Fabry-Perot spectroscopy for kinetic temperature and velocity measurements of a high enthalpy air plasma flow

    Science.gov (United States)

    Zander, Fabian; Löhle, Stefan; Hermann, Tobias; Fulge, Hannes

    2017-08-01

    The atomic translational temperatures and velocities of a low pressure, high enthalpy air plasma are measured using Fabry-Perot spectroscopy. The measurements presented here are the first measurements using this system at this enthalpy level. The sub-picometre resolution of the unique system has allowed accurate translational temperature and velocity measurements of the atomic species in the plasma. The detection system allows the Doppler broadening of multiple atomic nitrogen and oxygen lines to be measured simultaneously. Additionally, having two optical paths, one perpendicular to the flow and one at 45 deg. allows the Doppler shift to be measured. Measurements were taken during three different plasma wind tunnel tests. Mean atomic nitrogen temperatures of 1.08+/- 0.11 × 104 K and atomic oxygen translational temperatures of 1.23+/- 0.12 ×104 K were measured. The thermal non-equilibrium determined verified earlier measurements of the same phenomena, however, the mechanism behind this has not yet been determined. The mean measured flow velocity was 3350+/- 840~m~s-1 and was consistent between the atomic species. The translational temperature and velocity contribute approximately 35% of the local enthalpy of the flow. The direct measurement of these parameters, removing previously required assumptions, increases the fidelity of the flow characterisation significantly. This allows high quality testing to be conducted in this flow field.

  18. Experimental studies of electrical conductivities and P-wave velocities of gabbro at high pressures and high temperatures

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2003-01-01

    The P-wave velocities and electrical conductivities of gabbro were measured using ultrasonic transmission method and impedance spectroscopy from room temperature to 1100℃ at 1-2 GPa, and the factors controlling the P-wave velocity and the microscopic conductance mechanisms of the rock were analyzed. The experimental results show that the P-wave velocities of gabbro drop abruptly at temperatures of 800-850℃ and under pressures of 1-2 GPa due to the occurrence of grain boundary phases and dehydration melting; however, the electrical conductivities and electronic conduction mechanisms have not changed obviously at temperatures of 800-850℃. At temperatures Below 680℃, only one impedance arc (I) corresponding to grain interior conduction occurs at frequencies between 12 Hz and 105 Hz, the second arc (II) corresponding to grain boundary conduction occurs at temperatures above 680℃. The total conductivity of this rock is dominated by the grain interior conductivity as the occurrence of grain boundary conduction has a small effect on the total conductivity. The laboratory-measured velocities are consistent with the average P-wave velocity observations of lower crust and upper mantle. The conductivity values correspond well with the gabbroite composition of the lower crust and upper mantle; however, they are about 1-2 orders of magnitude lower than MT data from the high conductive layers. The experiments confirm that the dehydration of hydrous minerals can induce the partial melting, and the low seismic velocity zones might be correlated with the high conductive layers if partial melting occurs.

  19. Nucleons and isobars at finite density ({rho}) and temperature (T)

    Energy Technology Data Exchange (ETDEWEB)

    Cenni, R. [Dipt. di Fisica, Univ. di Genova (Italy); Istituto Nazionale di Fisica Nucleare, Genoa (Italy); Dey, J. [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Maulana Azad Coll., Calcutta (India); Dey, M. [Department of Physics, Presidency College, Calcutta 700 073 (India)

    2001-09-01

    The importance of studying matter at high {rho} increases as more astrophysical data becomes available from recently launched spacecrafts. The importance of high-T studies derives from heavy-ion data. In this paper we set up a formalism to study the nucleons and isobars with long- and short-range potentials non-pertubatively, bosonizing and expanding semi-classically the Feyman integrals up to one loop. We address the low-density, finite-T problem first, the case relevant to heavy-ion collisions, hoping to address the high-density case later. Interactions change the nucleon and isobar numbers at different {rho} and T non-trivially. (orig.)

  20. Nucleons and Isobars at finite density ($\\rho$) and temperature (T)

    CERN Document Server

    Cenni, R; Dey, M; Cenni, Rinaldo; Dey, Jishnu; Dey, Mira

    2001-01-01

    The importance of studying matter at high $\\rho$ increases as more astrophysical data becomes available from recently launched spacecrafts. The importance of high T studies derives from heavy ion data. In this paper we set up a formalism to study the nucleons and isobars with long and short range potentials non-pertubatively, bosonizing and expanding semi-classically the Feyman integrals up to one loop. We address the low density, finite T problem=A0 first, the case relevant to heavy ion collisions, hoping to adresss the high density case later. Interactions change the nucleon and isobar numbers at different $\\rho$ and T non-trivially.

  1. Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

    Institute of Scientific and Technical Information of China (English)

    杨树锋; 陈汉林; 姜继双; 竺国强; 谢鸿森; 侯渭; 张月明; 徐惠刚

    1997-01-01

    The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure hoost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The "softening point" of compressional wave velocity ( Vp) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of "softening", Vp after "softening" and the percentage of Vp’ s drop around the "softening point" for two types of granitoids are obviously different. The depth of "softening" is 15 km approximately and Vp after "softening" is 5. 62 km/s for S-type granitoid. But for I-type granitoid the depth of "softening" is 26 km approximately and Vp after "softening" is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the "softening" of elastic-wave velocity is caused by t

  2. Ultramassive dense early-type galaxies: Velocity dispersions and number density evolution since z = 1.6

    Science.gov (United States)

    Gargiulo, A.; Saracco, P.; Tamburri, S.; Lonoce, I.; Ciocca, F.

    2016-08-01

    Aims: We investigate the stellar mass assembly history of ultramassive (M⋆ ≳ 1011M⊙) dense (Σ = M⋆/2πRe2> 2500M⊙ pc-2) early-type galaxies (ETGs, elliptical and spheroidal galaxies) selected on basis of visual classification over the last 9 Gyr. Methods: We traced the evolution of the comoving number density ρ of ultramassive dense ETGs and compared their structural (effective radius Re and stellar mass M⋆) and dynamical (velocity dispersion σe) parameters over the redshift range 0 advantage of the COSMOS spectroscopic survey to probe the intermediate redshift range [0.2-1.0]. We derived the number density of ultramassive dense local ETGs from the SDSS sample taking all of the selection bias affecting the spectroscopic sample into account. To compare the dynamical and structural parameters, we collected a sample of 11 ultramassive dense ETGs at 1.2 measurements are available. For four of these ETGs (plus one at z = 1.91), we present previously unpublished estimates of velocity dispersion, based on optical VLT-FORS2 spectra. We probe the intermediate redshift range (0.2 ≲ z ≲ 0.9) and the local Universe with different ETGs samples. Results: We find that the comoving number density of ultramassive dense ETGs evolves with z as ρ(z) ∝ (1 + z)0.3 ± 0.8 implying a decrease of ~25% of the population of ultramassive dense ETGs since z = 1.6. By comparing the structural and dynamical properties of high-z ultramassive dense ETGs over the range 0 ≲ z < 1.6 in the [Re, M⋆, σe] plane, we find that all of the ETGs of the high-z sample have counterparts with similar properties in the local Universe. This implies either that the majority (~70%) of ultramassive dense ETGs already completed the assembly and shaping at ⟨ z ⟩ = 1.4, or that, if a significant portion of dense ETGs evolves in size, new ultramassive dense ETGs must form at z < 1.5 to maintain their number density at almost constant. The difficulty in identify good progenitors for these

  3. Temperature jump induced force generation in rabbit muscle fibres gets faster with shortening and shows a biphasic dependence on velocity.

    Science.gov (United States)

    Ranatunga, K W; Roots, H; Offer, G W

    2010-02-01

    We examined the tension responses to ramp shortening and rapid temperature jump (muscle fibres at 8-9 degrees C (the fibre length (L(0)) was approximately 1.5 mm and sarcomere length 2.5 microm). The aim was to investigate the strain sensitivity of crossbridge force generation in muscle. The T-jump induced tension rise was examined during steady shortening over a wide range of velocities (V) approaching the V(max) (V range approximately 0.01 to approximately 1.5 L(0) s(1)). In the isometric state, a T-jump induced a biphasic tension rise consisting of a fast (approximately 50 s(1), phase 2b) and a slow (approximately 10 s(1), phase 3) component, but if treated as monophasic the rate was approximately 20 s(1). During steady shortening the T-jump tension rise was monophasic; the rate of tension rise increased linearly with shortening velocity, and near V(max) it was approximately 200 s(1), approximately 10x faster than in the isometric state. Relative to the tension reached after the T-jump, the amplitude increased with shortening velocity, and near V(max) it was 4x larger than in the isometric state. Thus, the temperature sensitivity of muscle force is markedly increased with velocity during steady shortening, as found in steady state experiments. The rate of tension decline during ramp shortening also increased markedly with increase of velocity. The absolute amplitude of T-jump tension rise was larger than that in the isometric state at the low velocities (shortening velocity is increased, probably enhancement of crossbridge force generation and faster (post-stroke) crossbridge detachment by negative strain. Overall, our results show that T-jump force generation is strain sensitive and becomes considerably faster when exposed to negative strain. Thus the crossbridge force generation step in muscle is both temperature sensitive (endothermic) and strain sensitive.

  4. Porosity and sonic velocity depth trends of Eocene chalk in Atlantic Ocean: Influence of effective stress and temperature

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Fabricius, Ida Lykke

    2014-01-01

    . This indicates pore-filling cementation via an activation energy mechanism. We proposed a predictive equation for porosity reduction with burial stress. This equation is relevant for basin analysis and hydrocarbon exploration to predict porosity if sonic velocity data for subsurface chalk is available.......We aimed to relate changes in porosity and sonic velocity data, measured on water-saturated Eocene chalks from 36 Ocean Drilling Program drill sites in the Atlantic Ocean, to vertical effective stress and thermal maturity. We considered only chalk of Eocene age to avoid possible influence...... of geological age on chalk compaction trends. For each depth, vertical effective stresses as defined by Terzaghi and by Biot were calculated. We used bottom-hole temperature data to calculate the time–temperature index of thermal maturity (TTI) as defined by Lopatin. Porosity and compressional wave velocity...

  5. Viscosity and density of methanol/water mixtures at low temperatures

    Science.gov (United States)

    Austin, J. G.; Kurata, F.; Swift, G. W.

    1968-01-01

    Viscosity and density are measured at low temperatures for three methanol/water mixtures. Viscosity is determined by a modified falling cylinder method or a calibrated viscometer. Density is determined by the volume of each mixture contained in a calibrated glass cell placed in a constant-temperature bath.

  6. An Instrument for the Simultaneous Measurement of Velocity, Temperature and Density in Unseeded Air Flows.

    Science.gov (United States)

    1989-01-31

    R.R.ReevesJr., "Ultraviolet Absorption Coefficient oi CO2, Co, 02, H20, N20, NH3, NO, SO 2, and CH 4 Between 1850 and 4000 A.", J.Geo.Res., Vol. 68 , No.24...34, Van Nostrand Co.,1950.I 32. H. A. Gebbie, W. J. Burroughs, J. A. Robb, and G. R. Bird, Nature, 212, 66, (1966). 33. D. Marcuse , Engineering Ouantum Electrodynamics. Harcourt, Brace, and World, Inc., New York, (1970). I * 58 I

  7. Mantle Composition and Temperature of Western North America Revealed from Direct P and S Wave Velocities of KLB-1 Peridotite to the Condition of Transition Zone

    Science.gov (United States)

    Wang, X.; Chen, T.; Qi, X.; Zou, Y.; Liebermann, R. C.; Li, B.

    2015-12-01

    Comparing the elasticity of candidate compositional models with seismic profiles (e.g., PREM and AK135) is one of the most important geophysical approaches to constrain the mineralogical composition of the mantle. However in such averaging schemes (e.g., Voigt-Reuss-Hill), it is difficult to take into account all of the mineralogical and chemical complexities; we therefore undertook elasticity study of a natural mantle rock sample at high pressures and temperatures. In this study, a series of polycrystalline aggregates of peridotite KLB-1 (from Kilbourne Hole, New Mexico) were hot-pressed at pressures of 3-15 GPa and temperatures of 1200-1400°C. Scanning electron microscopy (SEM), Electron Microprobe Analysis (EPMA) and X-ray diffraction (XRD) were used to characterize the texture, grain size, and composition of these well-sintered specimens. For the first time in history, the P and S wave velocities of a pyrolitic multiphase aggregate were directly measured at mantle transition zone pressures and temperatures using ultrasonic interferometry. Based on the phase fractions from EPMA and the P and S wave velocities from in situ measurement at high pressure and high temperature, the velocities of the KLB-1 peridotite along 1200-1400 oC adiabatic mantle geotherms were obtained and compare well with the seismic models of western North America, the region where these peridotite KLB-1 samples were collected. The comparison with regional seismic models of western North America (e.g., GCA and TNA/TNA2) as well as global seismic models (PREM and AK135) place unprecedented constraints on the composition, temperature and density profiles for the upper mantle in this region, which can help us understand the nature of thermal and tectonic processes of the Rio Grande Rift.

  8. Temperature and air velocity effects on ethanol emission from corn silage with the characteristics of an exposed silo face

    Science.gov (United States)

    Montes, Felipe; Hafner, Sasha D.; Rotz, C. Alan; Mitloehner, Frank M.

    2010-05-01

    Volatile organic compounds (VOCs) from agricultural sources are believed to be an important contributor to tropospheric ozone in some locations. Recent research suggests that silage is a major source of VOCs emitted from agriculture, but only limited data exist on silage emissions. Ethanol is the most abundant VOC emitted from corn silage; therefore, ethanol was used as a representative compound to characterize the pattern of emission over time and to quantify the effect of air velocity and temperature on emission rate. Ethanol emission was measured from corn silage samples removed intact from a bunker silo. Emission rate was monitored over 12 h for a range in air velocity (0.05, 0.5, and 5 m s -1) and temperature (5, 20, and 35 °C) using a wind tunnel system. Ethanol flux ranged from 0.47 to 210 g m -2 h -1 and 12 h cumulative emission ranged from 8.5 to 260 g m -2. Ethanol flux was highly dependent on exposure time, declining rapidly over the first hour and then continuing to decline more slowly over the duration of the 12 h trials. The 12 h cumulative emission increased by a factor of three with a 30 °C increase in temperature and by a factor of nine with a 100-fold increase in air velocity. Effects of air velocity, temperature, and air-filled porosity were generally consistent with a conceptual model of VOC emission from silage. Exposure duration, temperature, and air velocity should be taken into consideration when measuring emission rates of VOCs from silage, so emission rate data obtained from studies that utilize low air flow methods are not likely representative of field conditions.

  9. Numerical simulation of bubble behavior in subcooled flow boiling under velocity and temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Bahreini, Mohammad, E-mail: m.bahreini1990@gmail.com; Ramiar, Abas, E-mail: aramiar@nit.ac.ir; Ranjbar, Ali Akbar, E-mail: ranjbar@nit.ac.ir

    2015-11-15

    Highlights: • Condensing bubble is numerically investigated using VOF model in OpenFOAM package. • Bubble mass reduces as it goes through condensation and achieves higher velocities. • At a certain time the slope of changing bubble diameter with time, varies suddenly. • Larger bubbles experience more lateral migration to higher velocity regions. • Bubbles migrate back to a lower velocity region for higher liquid subcooling rates. - Abstract: In this paper, numerical simulation of the bubble condensation in the subcooled boiling flow is performed. The interface between two-phase is tracked via the volume of fluid (VOF) method with continuous surface force (CSF) model, implemented in the open source OpenFOAM CFD package. In order to simulate the condensing bubble with the OpenFOAM code, the original energy equation and mass transfer model for phase change have been modified and a new solver is developed. The Newtonian flow is solved using the finite volume scheme based on the pressure implicit with splitting of operators (PISO) algorithm. Comparison of the simulation results with previous experimental data revealed that the model predicted well the behavior of the actual condensing bubble. The bubble lifetime is almost proportional to bubble initial size and is prolonged by increasing the system pressure. In addition, the initial bubble size, subcooling of liquid and velocity gradient play an important role in the bubble deformation behavior. Velocity gradient makes the bubble move to the higher velocity region and the subcooling rate makes it to move back to the lower velocity region.

  10. An analysis of the temperature dependence of force, during steady shortening at different velocities, in (mammalian) fast muscle fibres.

    Science.gov (United States)

    Roots, H; Ranatunga, K W

    2008-01-01

    We examined, over a wide range of temperatures (10-35 degrees C), the isometric tension and tension during ramp shortening at different velocities (0.2-4 L(0)/s) in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L(0)) was 2.2 mm and sarcomere length approximately 2.5 microm. During a ramp shortening, the tension change showed an initial inflection of small amplitude (P(1)), followed by a larger exponential decline towards an approximate steady level; the tension continued to decline slowly afterwards and the approximate steady tension at a given velocity was estimated as the tension (P(2)) at the point of intersection between two linear slopes, as previously described (Roots et al. 2007). At a given temperature, the tension P(2) declined to a lower level and at a faster rate (from an exponential curve fit) as the shortening velocity was increased; the temperature sensitivity of the rate of tension decline during ramp shortening at different velocities was low (Q(10) 0.9-1.5). The isometric tension and the P(2) tension at a given shortening velocity increased with warming so that the relation between tension and (reciprocal) temperature was sigmoidal in both. In isometric muscle, the temperature T(0.5) for half-maximal tension was approximately 10 degrees C, activation enthalpy change (DeltaH) was approximately 100 kJ mol(-1) and entropy change (DeltaS) approximately 350 J mol(-1) K(-1). In shortening, these were increased with increase of velocity so that at a shortening velocity (approximately 4 L(0)/s) producing maximal power at 35 degrees C, T(0.5) was approximately 28 degrees C, DeltaH was approximately 200 kJ mol(-1) and DeltaS approximately 700 J mol(-1) K(-1); the same trends were seen in the tension data from isotonic release experiments on intact muscle and in ramp shortening experiments on maximally Ca-activated skinned fibres. In general, our findings show that the sigmoidal relation between force and

  11. Nucleons and Isobars at finite density ($\\rho$) and temperature (T)

    OpenAIRE

    Cenni, Rinaldo; Dey, Jishnu; Dey, Mira

    2001-01-01

    The importance of studying matter at high $\\rho$ increases as more astrophysical data becomes available from recently launched spacecrafts. The importance of high T studies derives from heavy ion data. In this paper we set up a formalism to study the nucleons and isobars with long and short range potentials non-pertubatively, bosonizing and expanding semi-classically the Feyman integrals up to one loop. We address the low density, finite T problem=A0 first, the case relevant to heavy ion coll...

  12. Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

    Science.gov (United States)

    Chang, A. Y.; Battles, B. E.; Hanson, R. K.

    1990-01-01

    In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.

  13. Probe and method for simultaneous measurements of ''true'' instantaneous temperature and three velocity components in turbulent flow.

    Science.gov (United States)

    Fabris, G

    1978-05-01

    In the measurement of turbulent flows the need has always existed to obtain correct instantaneous values of temperature and three components of velocity at a particular point. Many proposed lengthy approximate correction methods that attempt to account for ''nonlinear'' effects (cross contamination between different quantities) in hot-wire measurements cannot be considered satisfactory. The availability of powerful digital computers for theoretical and experimental studies has placed pressure on experimentalists to develop better probes and methods. This paper attempts to answer these pressures by describing the development of a special four-wire probe and a method of processing the obtained signals. The use of four 0.625-microm-diam sensors makes the probe practically interference free. The processing method is based on the simultaneous solution of four complete nonlinear response equations for the sensors, yielding in principle exact instantaneous values of velocity components and temperature. Additional features of the processing method include: instantaneous full correction for tunnel free stream velocity and temperature fluctuations, first-order correction for dc drifts of the signals during data acquisition, subtraction of all 60-Hz related noise, and correction for streamwise displacement of sensors based on instantaneous streamwise velocity.

  14. Analysis and optimization of gas-thermal spray process in terms of condensed phase velocity and temperature

    Science.gov (United States)

    Dolmatov, A. V.; Gulyaev, I. P.; Kuzmin, V. I.; Lyskov, E. A.; Ermakov, K. A.

    2017-01-01

    The paper presents the experimental results for velocity and tempertaure disibutions of the condensed phase in a plasma jet from the plasmatorch PNK-50 (design from ITAM SB RAS, Novosibirsk). The plasma jet is used at different operational modes for thermal spraying of nickel alloy powder PR-NKh16SR3. The measurements for average velocity (230-280 m/s) and temperature (2290-2410 K) of sprayed particles were matched to data on microhardness (630-710 HV) and porosity (1.7-13.5 %) of samples. Results were transferred into coating properties maps plotted in coordinates "arc current vs. torch offset" and "particle velocity vs. particle temperature". Experiments demonstrated the change in parameters of condensed phase in the jet after performimg of maintenance job for the plasmatorch. We propose the method for adjusting the operational parameters of thermal spraying equipment using optical methods of control for particle velocity and particle temperature. The exemplary apparatus function of the plasmatorch was plotted; an approach is proposed for optimization and transfer of spraying technology of coatings with specified properties between equipment from different manufacturers, different class and power.

  15. High Density Planar High Temperature Superconducting Josephson Junctions Arrays

    Science.gov (United States)

    2006-09-01

    TIT,) 3 dependance . At lower temperatures it follows a (1 - T/T,)2 depen- dance ........ ................................... 57 4.7 Shapiro steps in...70 4.23 Dependance of the critical current for a ten junction array on mi- crowave power ..................................... 71 4.24 Resistance vs...GHz microwave radiation. (b) Microwave power dependance of the critical current and 1st-order Shapiro step. 76 5.2 (a) Single junction critical current

  16. The XMM Cluster Survey: evolution of the velocity dispersion–temperature relation over half a Hubble time

    OpenAIRE

    2016-01-01

    We measure the evolution of the velocity dispersion--temperature ($\\sigma_{\\rm v}$--$T_{\\rm X}$) relation up to $z = 1$ using a sample of 38 galaxy clusters drawn from the \\textit{XMM} Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 $z > 0.5$ clusters observed with the GMOS instruments on the Gemini telescop...

  17. The XMM cluster survey:evolution of the velocity dispersion-temperature relation over half a Hubble time

    OpenAIRE

    Wilson, Susan; Rooney, Philip J; Caldwell, Caroline; Kay, Scott T; Collins, Chris A.; McCarthy, Ian G.; Romer, A. Kathy; Bermeo, Alberto; Bernstein, Rebecca; da Costa, Luiz; Gifford, Daniel; Hollowood, Devon; Hoyle, Ben; Jeltema, Tesla; Liddle, Andrew R.

    2016-01-01

    We measure the evolution of the velocity dispersion-temperature (sigma(v)-T-X) relation up to z = 1 using a sample of 38 galaxy clusters drawn from the XMM Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high-redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 z > 0.5 clusters observed with the Gemini Multi Object Spectographs instruments on the Gemini telescopes....

  18. Chemical sputtering of graphite by low temperature nitrogen plasmas at various substrate temperatures and ion flux densities

    NARCIS (Netherlands)

    Bystrov, K.; Morgan, T. W.; Tanyeli, I.; De Temmerman, G.; M. C. M. van de Sanden,

    2013-01-01

    We report measurements of chemical sputtering yields of graphite exposed to low temperature nitrogen plasmas. The influence of surface temperature and incoming ion energy on the sputtering yields has been investigated in two distinct ion flux density regimes. Sputtering yields grow consistently with

  19. Temperature dependence of Hall electron density of GaN-based heterostructures

    Institute of Scientific and Technical Information of China (English)

    Zhang Jin-Feng; Zhang Jin-Cheng; Hao Yue

    2004-01-01

    The theoretic calculation and analysis of the temperature dependence of Hall electron density of a sample AlGaN/GaN heterostructure has been carried out in the temperature range from 77 to 300K. The densities of the twodimensional electron gas and the bulk electrons are solved by self-consistent calculation of one-dimensional Schrodinger and Poisson equations at different temperatures, which allow for the variation of energy gap and structure strain, and are used for evaluation of the temperature dependence of Hall electron density. The calculated Hall electron density agrees with the measured one quite well with the appropriate bulk mobility data. Analysis revealed that for the temper ature range considered, even in the heterostructures with a small bulk conductance the factors that determine the Hall mobility and electron density could be of different sources, and not just the two-dimensional electron gas as generally supposed.

  20. Thermodynamic extension of density-functional theory. II. Finite-temperature ensemble spin-density functional theory

    CERN Document Server

    Balawender, Robert

    2009-01-01

    The formalism developed in the first paper of the series [arXiv:0901.1060v3] is applied to two thermodynamic systems: (i) of three global observables (the energy, the total electron number and the spin number), (ii) of one global observable (the internal electron energy) and two local (position-dependent) observables (the total electron density and the spin density). The two-component potential of the many-electron system of interest is constructed of a scalar external potential and a collinear magnetic field (coupled only with the spin operator). Various equilibrium characteristics of two systems are defined and investigated. Conditions for the equivalence between two systems (the same equilibrium density matrix demanded) are derived and thoroughly discussed. The applicability of the Hohenberg-Kohn theorem is extended to the thermodynamic spin-density functional theory. Obtained results provide a rigorous mathematical foundation for future derivation of the zero-temperature limit of this theory and determina...

  1. NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

    CERN Document Server

    Butsky, Iryna; Dutton, Aaron A; Wang, Liang; Stinson, Greg S; Penzo, Camilla; Kang, Xi; Keller, Ben W; Wadsley, James

    2015-01-01

    We show the effect of galaxy formation on the dark matter (DM) distribution across a wide range of halo masses. We focus on how baryon physics changes the dark matter halo shape, the so called "pseudo phase-space density distribution" and the velocity distribution within the virial radius, Rvir and in the solar neighborhood. This study is based on the NIHAO galaxy formation simulations, a large suite of cosmological zoom-in simulations. The galaxies reproduce key properties of observed galaxies, and hence offer unique insight into how baryons change the dark matter morphology and kinematics. When compared to dark matter only simulations, the NIHAO haloes have similar shapes at Rvir, but are substantially rounder inside ~0.1 Rvir. In DM-only simulations the inner halo has a minor-to-major axis ratio of c/a~0.5. In hydro simulations c/a increases with halo mass and integrated star formation efficiency, reaching ~0.8 at the Milky Way mass, reconciling a long-standing conflict between observations and DM only sim...

  2. Development of high temperature superconductors having high critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H

    2000-08-01

    Fabrication of high T{sub c} superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm{sup 2} and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation.

  3. Revisiting strong coupling QCD at finite baryon density and temperature

    CERN Document Server

    Fromm, M

    2008-01-01

    The strong coupling limit ($\\beta_{gauge}=0$) of lattice QCD with staggered fermions enjoys the same non-perturbative properties as continuum QCD, namely confinement and chiral symmetry breaking. In contrast to the situation at weak coupling, the sign problem which appears at finite density can be brought under control for a determination of the full (mu,T) phase diagram by Monte Carlo simulations. Further difficulties with efficiency and ergodicity of the simulations, especially at the strongly first-order, low-T, finite-mu transition, are addressed respectively with a worm algorithm and multicanonical sampling. Our simulations reveal sizeable corrections to the old results of Karsch and Muetter. Comparison with analytic mean-field determinations of the phase diagram shows discrepancies of O(10) in the location of the QCD critical point.

  4. Temperature dependence of the liquid eutectic lead-lithium alloy density

    Institute of Scientific and Technical Information of China (English)

    Alchagirov; Boris; B.; Mozgovoi; Alexandr; G.; Taova; Tamara; M.

    2005-01-01

    Lead-lithium alloys are of great interest for practice as the advanced materials to be used in new technique, nuclear energetics, and so forth. Terefore, study on the physico-chemical properties of the latter is of major significance. An analysis of the available literature shows that there are a few works, devoted to study of Pb-Li alloys densities. However, temperature dependence of the density ρ(T), and its temperature coefficientK=dρ/dT for eutectic alloy were obtained by either extrapolation of the density data up to the eutectic alloy's composition, or calculation method. There is a certain discrepancy amounting to as high as 4%, while the allowable error in the density measurements is less than 0.5%. The discrepancy between the results for the temperature coefficients of density amounts to 80%.In this work we present the experimental data on the temperature dependence of Ph0.83 Li0.17 eutectic alloy's density in the temperature range 520K to 643 K. The alloys were prepared using Pb and Li with 99. 999% and 99.8% contents of the basic elements, respectively. We use the improved device, which permits to get the results with error less than 0. 15%. The results of 115 measurements of density in 520K to 643K temperature range were processed by the least-square method. Density polytherm of Pb0.83 Li0. 17 eutectic alloy is described by linear equation ρ(T) =9507.89-0. 79813(T-508) , kg/m3 ,where T is the absolute temperature by K. Mearsurement error was 0. 12% at 95% reliability.Discrepancy in the temperature coefficient data was 1.08%.Thus, the temperature dependence of the Pb-Li eutectic alloy density was studied by the precise two-capillary method. The obtained results may be recommended as the most reliable reference data.

  5. The Effect of Temperature and Nanoclay on the Low Velocity and Ballistic Behavior of Woven Glass-Fiber Reinforced Composites

    Science.gov (United States)

    Patrin, Lauren

    The objective of this research was to study the effect of nanoclay and temperature on the behavior of woven glass-fabric reinforced epoxy composite under low velocity and ballistic impacts. The materials used in manufacturing the composite were S2 (6181) glass-fibers, epoxy resin (EPON 828), hardener (Epikure 3230), nanoclay and Heloxy 61 modifier. The nanoclay addition was 0%, 1%, 3% and 5% by weight, with respect to the resin. All specimens were manufactured at the City College facilities using vacuum infusion. Tensile tests were conducted to characterize the material and obtain the Young's modulus, ultimate stress, failure strain, Poisson's ratio, shear modulus and shear strength and their variation with nanoclay percentage and temperature. The tests were conducted at room temperature (21°C/70°F), -54°C (-65°F), -20°C (-4°F), 49°C (120°F) and 71°C (160°F). Next composite specimens with 0%, 1%, 3% and 5% nanoclay by weight, with respect to the resin, were subjected to low velocity impact at the previously specified temperatures to determine dynamic force, displacement and energy correlations. The extent of damage was studied using the ultrasound technique. Then ballistic tests were conducted on the nanoclay infused specimens at room temperature to obtain the ballistic limit (V50) and the damage behavior of the composite. The dynamic finite element analysis (FEA) software LS-DYNA was used to model and simulate the results of low velocity impact tests. Good agreement was obtained between experimental and numerical (FEA) results. Analytical analyses were undertaken to compare the results from the tensile experiments. The finite element analysis (FEA) allowed for further analytical comparison of the results. The FEA platform used was LS-DYNA due to its proficient dynamic and damage capabilities in composite materials. The FEA was used to model and simulate the low velocity impacts and compare the results to experiments.

  6. Phase transition in finite density and temperature lattice QCD

    CERN Document Server

    Wang, Rui; Gong, Ming; Liu, Chuan; Liu, Yu-Bin; Liu, Zhao-Feng; Ma, Jian-Ping; Meng, Xiang-Fei; Zhang, Jian-Bo

    2015-01-01

    We investigate the behavior of the chiral condensate in lattice QCD at finite temperature and finite chemical potential. The study was done using two flavors of light quarks and with a series of $\\beta$ and $ma$ at the lattice size $24\\times12^{2}\\times6$. The calculation was done in the Taylar expansion formalism. We are able to calculate the first and second order derivatives of $\\langle\\bar{\\psi}\\psi\\rangle$ in both isoscalar and isovector channels. With the first derivatives being small, we find that the second derivatives are sizable close to the phase transition and the magnitude of $\\bar{\\psi}\\psi$ decreases under the influence of finite chemical potential in both channels.

  7. Dyson-Schwinger Equation Density, Temperature and Continuum Strong QCD

    CERN Document Server

    Roberts, C D

    2000-01-01

    Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions; and the transition to, and properties of, a quark gluon plasma. We provide a contemporary perspective, couched primarily in terms of the Dyson-Schwinger equations but also making comparisons with other approaches and models. Our discourse provides a practitioners' guide to features of the Dyson-Schwinger equations [such as confinement and dynamical chiral symmetry breaking] and canvasses phenomenological applications to light meson and baryon properties in cold, sparse QCD. These provide the foundation for an extension to hot, dense QCD, which is probed via the introduction of the intensive thermodynamic variables: chemical potential and temperature. We describe order parameters whose evolution signals deconfinement and chiral symmetry restoration, and chronicle their use in demarcating the quark gluon...

  8. Joint Inversion of Geoid Anomaly and Teleseismic P-Wave Delay Times: Modeling Density and Velocity Perturbations Beneath the Parana Magmatic Province

    Science.gov (United States)

    Chaves, C. A. M.; Ussami, N.; Ritsema, J.

    2014-12-01

    The Parana Magmatic Province (PMP) is one of the largest continental igneous provinces (LIP) on Earth. It is well dated at 133 Ma preceding the opening of the South Atlantic Ocean, but the causative geodynamic processes are still poorly understood. Although a low-velocity anomaly has been imaged by seismic tomography in the northeast region of the PMP and interpreted as a fossil conduct of a mantle plume that is related to the flood basalt eruptions, geochemical data indicate that such magmatism is caused by the melting of a heterogeneous and enriched lithospheric mantle with no deep plume participation. Models of density perturbations in the upper mantle estimated from joint inversion of geoid anomalies and P-wave delay times will offer important constraints on mantle dynamics. A new generation of accurate global geopotential models derived from satellite-missions (e.g. GRACE, GOCE) allows us to estimate density distribution within the Earth from geoid inversion. In order to obtain the residual geoid anomaly related to the density structure of the mantle, we use the EGM2008 model removing estimated geoid perturbations owing to variations in crustal structure (i.e., topographical masses, Moho depth, thickness of sediments and basalts). Using a spherical-Earth approximation, the density model space is represented by a set of tesseroids and the velocity model is parameterized in nodes of a spherical grid where cubic B-splines are utilized as an interpolation function. To constrain the density inversion, we add more than 10,000 manually picked teleseismic P-wave delay times. During the inversion procedure, density and P-wave velocity are linked through the optimization of a constant linear factor correlating density and velocity perturbation. Such optimization will be performed using a probability density function (PDF) [Tarantola, 2005]. We will present the preliminary results of this joint inversion scheme and hypothesize on the geodynamic processes responsible for

  9. Velocity Field of Thermocapillary Convection in High-Temperature Oxide Solution

    Institute of Scientific and Technical Information of China (English)

    JIN Wei-Qing; LIANG Xin-An; PAN Zhi-Lei; LIU Zhao-Hua; YODA Shinichi; JIANG Yuan-Fang; SHEN Guo-Tu

    2001-01-01

    We have investigated experimentally and theoretically the thermocapillary convective flow phenomena in a loopshaped Pt wire heater of KNbO3 (20wt.%) and Li2B4O7 solutions. Optical evaluations in connection with thermocouple measurements made it possible to get a new type of thermocapillary convective flow in the considered system. To study the kinematical behaviour of thermocapillary convection, we have measured the stream flow velocities. In a theoretical analysis, the flow velocity due to the thermocapillary effect alone was estimated by balancing the surface tension forces by viscous forces. The velocity distribution in the solution near the margin of the heater was obtained, which is in agreement with the experimental result.

  10. VELOCITY FIELD OF THERMOCAPILLARY CONVECTION IN HIGH-TEMPERATURE OXIDE SOLUTION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ We have investigated experimentally and theoretically the thermocapillary convec tive flow phenomena in a loop-shaped Pt wire heater of KNbO3 (20wt.%) and Li2B4O7 solutions. Optical evaluations in connection with thermocouple measure ments made it possible to get a new type of thermocapillary convective flow in the considered system. To study the kinematical behaviour of thermocapillary convec tion, we have measured the stream flow velocities. In a theoretical analysis, the flow velocity due to the thermocapillary effect alone was estimated by balancing the sur face tension forces by viscous forces. The velocity distribution in the solution near the margin of the heater was obtained, which is in agreement with the experimental result.

  11. Study of the ventilation at ATLAS cavern UX15 air velocity and temperature around the muon chambers

    CERN Document Server

    Vigo-Castellví, E

    2000-01-01

    The Muon Chambers of ATLAS detector cannot work under temperature differences between two opposed faces above 3 K. In addition, a low velocity of the air around the Muon Chambers is essential to avoid vibration problems. The CV group at the ST division is involved in an airflow simulation inside UX15 cavern to check air temperature and velocity profiles around the ATLAS Muon Chambers. In this paper, the status and the content of the performed theoretical studies will be explained. Three simulation models, which helped to understand the Muon Spectrometer thermal environment and the efficiency of the ventilation system at ATLAS cavern, will be presented. Besides, it will be shown how these studies support the proposal of a deeper individual Muon Chamber study.

  12. Numerical Analysis of the Slip Velocity and Temperature-Jump in Microchannel Using Langmuir Slip Boundary Condition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Woo; Kim, Hyun Goo; Lee, Do Hyung [Hanyang University, Seoul (Korea, Republic of)

    2009-03-15

    The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

  13. SU($4$) Polyakov linear-sigma model at finite temperature and density

    CERN Document Server

    Diab, Abdel Magied; Tawfik, Abdel Nasser; Dahab, Eiman Abou El

    2016-01-01

    In mean-field approximation, the SU($4$) Polyakov linear - sigma model (PLSM) is constructed in order to characterize the quark-hadron phase structure in a wide range of temperatures and densities. The chiral condensates $\\sigma_l$, $\\sigma_s$ and $\\sigma_c$ for light, strange and charm quarks, respectively, and the deconfinement order-parameters $\\phi$ and $\\phi^*$ shall be analyzed at finite temperatures and densities. We conclude that the critical temperatures corresponding to charm condensates are greater than that to strange and light ones, respectively. Thus, the charm condensates are likely not affected by the QCD phase transition. Furthermore, increasing the chemical potentials decreases the corresponding critical temperatures.

  14. Velocity and density scaling at the outlet of a silo and its role in the expression of the mass flow rate

    Science.gov (United States)

    Maza, D.; Janda, A.; Rubio-Largo, S. M.; Zuriguel, I.; Hidalgo, R. C.

    2013-06-01

    The role of density and velocity profiles in the flow of particles through apertures has been recently put on evidence in a two-dimensional experiment (Phys. Rev. Lett. 108, 248001). For the whole range of apertures studied, both velocity and density profiles are selfsimilar and the obtained scaling functions allow to derive the relevant scales of the problem. Indeed, by means of the functionality obtained for these profiles, an exact expression for the mass flow rate was proposed. Such expression showed a perfect agreement with the experiential data. In this work, we generalize this study to the three dimensional case. We perform numerical simulations of a 3D silo in which the velocity and volume fraction profiles are determined. Both profiles shows that the scaling obtained for 2D can be generalized to the 3D case. Finally, the scaling of the mass flow rate with the outlet radius is discussed.

  15. Gulf of Maine - Water Salinity, Temperature and Sigma t (density) data from 1981 to 2005

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This table contains water salinity, temperature and sigma t (density) data from 1981 to 2005 binned at 10 meter depth intervals (from 300 meters up to 0 meters) for...

  16. Gulf of Maine - Water Salinity, Temperature and Sigma t (density) data from 1956 to 1980

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This table contains water salinity, temperature and sigma t (density) data from 1956 to 1980 binned at 10 meter depth intervals (from 300 meters up to 0 meters) for...

  17. Gulf of Maine - Water Salinity, Temperature and Sigma t (density) data from 1912 to 1930

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This table contains water salinity, temperature and sigma t (density) data from 1912 to 1930 binned at 10 meter depth intervals (from 300 meters up to 0 meters) for...

  18. Gulf of Maine - Water Salinity, Temperature and Sigma t (density) data from 1931 to 1955

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This table contains water salinity, temperature and sigma t (density) data from 1931 to 1955 binned at 10 meter depth intervals (from 300 meters up to 0 meters) for...

  19. Deformation and velocity measurements at elevated temperature in a fractured 0.5 M block of tuff

    Energy Technology Data Exchange (ETDEWEB)

    Blair, S.C.; Berge, P.A.

    1996-02-01

    This paper presents preliminary results of laboratory tests conducted on small block samples of Topopah Spring tuff, in support of the Yucca Mountain Site Characterization Project. The overall objective of these tests is to investigate the thermal-mechanical, thermal-hydrological, and thermal-chemical response of the rock to conditions similar to the near-field environment (NFE) of a potential nuclear waste repository. We present preliminary results of deformation and elastic wave velocity measurements on a 0.5-m-scale block of Topopah Spring tuff tested in uniaxial compression to 8.5 MPa and at temperatures to 85{degree}C. The Young`s modulus was found to be about 7 to 31 GPa for vertical measurements parallel to the stress direction across parts of the block containing no fractures or a few fractures, and 0.5 to 0.9 GPA for measurements across individual fractures, at ambient temperature and 8.5 MPa maximum stress. During stress cycles between 5 and 8.5 MPa, the deformation modulus values for the matrix with fractures were near 15-20 GPa at ambient temperature but dropped to about 10 GPa at 85{degree}C. Compressional wave velocities were found to be about 3.6 to 4.7 km/s at ambient temperature and stress. After the stress was cycled, velocities dropped to values as low as 2.6 km/s in the south end of the block where vertical cracks developed. Heating the block to about 85{degree}C raised velocities to as much as 5.6 km/s in the upper third of the block.

  20. FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Sivaraja Subramania Pillai

    2013-01-01

    Full Text Available This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k- ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.

  1. FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Sivaraja Subramania Pillai

    2013-06-01

    Full Text Available This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k-ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.

  2. Low density lipoprotein cholesterol level inversely correlated with coronary flow velocity reserve in patients with Type 2 diabetes

    Institute of Scientific and Technical Information of China (English)

    Jie Yu; Jiang-Li Han; Li-Yun He; Xin-Heng Feng; Wei-Hong Li; Jie-Ming Mao; Wei Gao; Guang Wang

    2013-01-01

    Objectives To evaluate the association of coronary artery endothelial function and plasma levels of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in patients with Type 2 Diabetes Mellitus (DM). Methods We investigated 90 participants from our institution between October 2007 to March 2010: non-DM (n = 60) and DM (n = 30). As an indicator of coronary endothelial dysfunction, we used non-invasive Doppler echocardiography to quantify coronary flow velocity reserve (CFVR) in the distal part of the left descending artery after rest and after intravenous adenosine administration. Results Plasma level of LDL-C was significantly higher in patients with DM than in non-DM (3.21 0.64 vs. 2.86 0.72 mmo/L, P < 0.05), but HDL-C level did not differ between the groups (1.01 0.17 vs. 1.05 0.19 mmo/L). Furthermore, the CFVR value was lower in DM patients than non-diabetics (2.45±0.62 vs. 2.98±0.68, P < 0.001). Plasma levels of LDL-C were negatively correlated with CFVR in all subjects (r = 0.35, P < 0.001; 95% confidence interval (CI): 0.52 -C0.15) and in the non-DM (r = 0.29, P < 0.05; 95% CI: 0.51–0.05), with an even stronger negative correlation in the DM group (r = 0.42, P < 0.05; 95% CI: 0.68 –0.06). Age (β = 0.019, s = 0.007, sβ = 0.435, 95% CI: 0.033 –0.005, P = 0.008), LDL-C (β = 0.217, s = 0.105, sβ = 0.282, 95% CI: 0.428 –0.005, P = 0.045) remained independently correlated with CFVR in the DM group. However, we found no correlation between HDL-C level and CFVR in any group. Conclusions Diabetes may contribute to coronary artery disease (CAD) by inducing dysfunction of the coronary artery endothelium. Increased LDL-C level may adversely impair coronary endothelial function in DM. HDL-C may lose its endothelial-protective effects, in part as a result of pathological conditions, especially under abnormal glucose metabolism.

  3. Density-temperature scaling of the fragility in a model glass-former

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Sengupta, Shiladitya; Sastry, Srikanth

    2013-01-01

    Dynamical quantities e.g. diffusivity and relaxation time for some glass-formers may depend on density and temperature through a specific combination, rather than independently, allowing the representation of data over ranges of density and temperature as a function of a single scaling variable...... of the activation free energy in the Adam-Gibbs relation, is consistent with the exponent values obtained by other means....

  4. Turbulence Measurements with the CIRES Tethered Lifting System during CASES-99: Calibration and Spectral Analysis of Temperature and Velocity.

    Science.gov (United States)

    Frehlich, Rod; Meillier, Yannick; Jensen, Michael L.; Balsley, Ben

    2003-10-01

    Finescale temperature and velocity measurements with multiple vertically spaced cold-wire and hot-wire sensors on the Cooperative Institute for Research in the Environmental Sciences (CIRES) tethered lifting system (TLS) were produced during the Cooperative Atmosphere-Surface Exchange Study-1999 (CASES-99). The various calibration methods are presented as well as algorithms to extract high-resolution estimates of the energy dissipation rate and the temperature structure constant C2T. The instrumentation is capable of measurements of 10-7 m2 s-3 and C2T 10-6 K2 m-2/3.

  5. Time evolution of chiral phase transition at finite temperature and density in the linear sigma model

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Koide, Tomoi; Maruyama, Masahiro [Tohoku Univ., Faculty of Science, Sendai, Miyagi (Japan)

    1999-08-01

    There are various approaches to nonequilibrium system. We use the projection operator method investigated by F. Shibata and N. Hashitsume on the linear sigma model at finite temperature and density. We derive a differential equation of the time evolution for the order parameter and pion number density in chiral phase transition. (author)

  6. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y; Mazzucato, E; Guttenfelder, W; Bell, R E; Domier, C W; LeBlanc, B P; Lee, K C; Luhmann Jr, N C; Smith, D R

    2011-03-21

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k⊥ρs ≤10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  7. Sound Velocities and Density of (Mg0.65, Fe0.35)O ferropericlase up to 1.4 Mbar

    Science.gov (United States)

    Chen, B.; Jackson, J. M.; Sturhahn, W.; Zhang, D.; Zhao, J.; Murphy, C. A.; Wicks, J. K.

    2010-12-01

    The Earth’s lower mantle accounts for more than half of the mass and volume of the planet. Iron is the most abundant transition-metal in the lower mantle, and it is hosted mainly by silicate perovskite, post-perovskite and ferropericlase. The spin-pairing transitions of iron from high-spin (HS) to low-spin (LS) state in ferropericlase have been recognized to affect the density and sound velocities of this second most abundant lower mantle phase (e.g. Speziale et al., 2005; Lin et al., 2005; Lin et al., 2006; Crowhurst et al., 2008; Marquardt et al., 2009; Zhuravlev et al., 2009). High-pressure and high-temperature physical properties of ferropericlase (Mg,Fe)O with various iron content are of significant importance for interpreting the seismological structure of the lower mantle in terms of compositional variations and for geodynamic modeling (e.g. Bower et al., 2009). We have determined the elastic and vibrational properties of (Mg0.65Fe0.35)O up to 1.4 Mbar at 300 K using nuclear resonant inelastic x-ray scattering (NRIXS) and in situ X-ray diffraction (XRD) measurements in diamond anvil cell at Sector 3 of Advanced Photon Source, Argonne National Laboratory. (Mg0.65Fe0.35)O contains the amount of iron within the estimated range expected for a “pyrolite” lower mantle (e.g. Westrenen et al., 2005; Sinmyo et al., 2008). From the low-energy region of the partial phonon density of states (PDoS), in situ XRD measurements, and our separate equation-of-state study with smaller pressure steps, we derived its shear and compressional velocities up to 1.4 Mbar. From integration of the PDoS, we also obtained Fe-weighted vibrational parameters as a function of pressure for this ferropericlase. Our new data provide fundamental new knowledge about the effects of spin transition and iron content on the density and sound velocities of ferropericlase in a previously uncharted pressure-composition sector. We will synthesize these effects by combining our results with those of

  8. Electrodialytic remediation of harbour sediment in suspension - Evaluation of effects induced by changes in stirring velocity and current density on heavy metal removal and pH

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.; Villumsen, Arne

    2009-01-01

    Electrodialytic remediation was used to remove heavy metals from a suspension of dredged harbour sediment. The studied metals Cu, Pb, Zn and Cd are normally strongly bound in anoxic sediment. Six electrodialytic laboratory remediation experiments were made, lasting 14 days and under oxic conditions....... The influence on the metal removal was investigated by changing current densities and stirring velocity of the sediment suspension. Using a current density of 1.0 mA/cm2 gave the highest metal removal. The sediment suspension was partly oxidised when mixed into a suspension for the electrodialytic remediation...... experiments and was further oxidised during the experiments. Even at low stirring velocities, oxic conditions were obtained. The metal removal was dependent on the achieved pH in the sediment and the highest metal removal and corresponding low pH was obtained by using a current density of 1.0 mA/cm2...

  9. The influence of temperature and salinity variability on the upper ocean density and mixed layer

    Directory of Open Access Journals (Sweden)

    R. W. Helber

    2010-08-01

    Full Text Available The relative influence of both temperature and salinity on the mixed layer depth (MLD is evaluated using a relationship of binned regressions of MLD on vertical density compensation and isothermal layer depth (ILD from a global set of in situ profile observations. Our approach is inspired by the observations of the difference between the MLD and the sonic layer depth (SLD that evolve seasonally around the global ocean. In this article, we hypothesize that vertical density compensation governs SLD-MLD differences and can be used for mapping the relative influence of temperature and salinity on upper ocean structure. The Turner angle, computed between the surface and 200 m (bulk Turner angle, BTA, serves as a measure of vertical density compensation that quantifies times and areas where either temperature or salinity is destabilizing. For temperature destabilization the ocean exhibits cool/fresh overlying hot/salty water. For salinity destabilization the ocean exhibits hot/salty overlying cool/fresh water. These two classes of density compensation have seasonal variability with different geographical characteristics. Profiles with salinity controlled stable density and destabilizing temperature gradient are found most often at high latitudes. Profiles with temperature controlled stable density and destabilizing salinity gradient are found in the tropics and subtropics of all oceans. Results indicate that about half of the ocean has vertical density compensation that is a necessary condition for SLD-MLD differences. While density compensation is necessary, it is not a sufficient condition for predicting the dependence of MLD on BTA. Density compensation is the dominant factor in MLD variability in heavy river input and subduction regions that cover only ~14% of the ocean.

  10. Scaling properties of velocity and temperature spectra above the surface friction layer in a convective atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    K. G. McNaughton

    2007-06-01

    Full Text Available We report velocity and temperature spectra measured at nine levels from 1.42 meters up to 25.7 m over a smooth playa in Western Utah. Data are from highly convective conditions when the magnitude of the Obukhov length (our proxy for the depth of the surface friction layer was less than 2 m. Our results are somewhat similar to the results reported from the Minnesota experiment of Kaimal et al. (1976, but show significant differences in detail. Our velocity spectra show no evidence of buoyant production of kinetic energy at at the scale of the thermal structures. We interpret our velocity spectra to be the result of outer eddies interacting with the ground, not "local free convection".

    We observe that velocity spectra represent the spectral distribution of the kinetic energy of the turbulence, so we use energy scales based on total turbulence energy in the convective boundary layer (CBL to collapse our spectra. For the horizontal velocity spectra this scale is (zi εo2/3, where zi is inversion height and εo is the dissipation rate in the bulk CBL. This scale functionally replaces the Deardorff convective velocity scale. Vertical motions are blocked by the ground, so the outer eddies most effective in creating vertical motions come from the inertial subrange of the outer turbulence. We deduce that the appropriate scale for the peak region of the vertical velocity spectra is (z εo2/3 where z is height above ground. Deviations from perfect spectral collapse under these scalings at large and small wavenumbers are explained in terms of the energy transport and the eddy structures of the flow.

    We find that the peaks of the temperature spectra collapse when wavenumbers are scaled using (z1/2 zi1/2. That is, the lengths of the thermal structures depend on both the lengths of the

  11. Climatology of Velocity and Temperature Turbulence Statistics Determined from Rawinsonde and ACARS/AMDAR Data

    Science.gov (United States)

    2010-06-01

    at 200 hPa. At smaller lags there is no systematic change in level with altitude. From Hoinka (1998), the annual mean tropo - pause level for the 408...Lindborg (2001, their Fig. 2) velocity structure functions from the MOZAIC tropo - spheric data. Since our analysis provides information at larger scales, a...of indices for clear air turbulence in the tropo - pause region derived from ERA40 re-analysis data. J. Geo- phys. Res., 112, D20106, doi:10.1029

  12. Velocity slip and temperature jump simulations by the three-dimensional thermal finite-difference lattice Boltzmann method.

    Science.gov (United States)

    Watari, Minoru

    2009-06-01

    Two problems exist in the current studies on the application of the lattice Boltzmann method (LBM) to rarefied gas dynamics. First, most studies so far are applications of two-dimensional models. The numbers of velocity particles are small. Consequently, the boundary-condition methods of these studies are not directly applicable to a multispeed finite-difference lattice Boltzmann method (FDLBM) that has many velocity particles. Second, the LBM and FDLBM share their origins with the Boltzmann equation. Therefore, the results of LBM and FDLBM studies should be verified by the results of the continuous Boltzmann equation. In my review to date on the LBM studies, it appears that such verifications were seldom done. In this study, velocity slip and temperature jump simulations in the slip-flow regime were conducted using a three-dimensional FDLBM model. The results were compared with preceding theoretical studies based on the continuous Boltzmann equation. The results agreed with the theory with errors of a few percent. To further improve the accuracy of the FDLBM, it seems necessary to increase the number of velocity particles.

  13. The experimental studies on electrical conductivities and P-wave velocities of anorthosite at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2002-01-01

    Results of P-wave velocity (vP) and electrical conductivity measurements on anorthosite are presented from room temperature to 880 (C at 1.0 GPa using ultrasonic transmission technique and impedance spectra technique respectively. The experiments show that the P-wave velocities in anorthosite decrease markedly above 680 (C following the dehydration of hydrous minerals in the rock, and the complex impedances collected from 12 Hz to 105 Hz only indicate the grain interior conduction mechanism at 1.0 GPa, from 410 (C to 750 (C. Because the fluids in the rock have not formed an interconnected network, the dehydration will not pronouncedly enhance the electrical conductivity and change the electrical conduction mechanism. It is concluded that the formation and evolution of the low-velocity zones and high-conductivity layers in the crust may have no correlations, and the dehydration can result in the formation of the low-velocity zones, but cannot simultaneously result in the high-conductivity layers.

  14. Electron drift velocities and electron mobilities in fast room-temperature dielectric liquids and their corresponding vapors

    Science.gov (United States)

    Faidas, H.; Christophorou, L. G.; McCorkle, D. L.; Carter, J. G.

    1990-09-01

    The drift velocity, w, of excess electrons as a function of the applied uniform electric field, E, in liquid tetramethylsilane (TMS), 2,2,4,4-tetramethylpentane (TMP), tetramethyltin (TMT), and in mixtures of TMS with TMP (molar ratio, M = 1.31/1) and n-pentane ( M = 102/1; 17/1; 5.6/1) has been measured up to E-values of ˜ 10 5 V cm -1 or density ( N)-reduced ele ctric held E/ N-values of ˜ 3 × 10 -17 V cm 2. The maximum w attained for these liquids, and the corresponding values of E are: 7.2 × 10 6 cm s -1 at 125 kV cm -1 for TMS, 6.0 × 10 6 cm s -1 at 75 kV cm -1 for TMS, 2.6 × 10 6 cm s -1 at 115 kV cm -1 for TMP, 3.2 × 10 6 cm s -1 at 105 kV cm -1 for TMS/TMP ( M = 1.31/1), 6.8 × 10 6 cm s -1 at 105 kV cm -1 for TMS/n-pentane ( M = 102/1), 6.8 × 10 6 cm s -1 at 145 kV cm -1 for TMS/n-pentane ( M = 17/1), and 4.9 × 10 6 cm s -1 at 145 kV cm -1 for TMS/n-pentane ( M = 5.6/1). The thermal-electron mobilities in the above liquid media are respectively 119.3, 85.7, 31.8, 39.1, 118, 85, and 47.6 cm 2 s -1 V -1. Also, w was measured as a function of E/ N for TMS, TMP, and neopentane vapors at room temperature and is compared with that in the corresponding liquids. Properties of these media which make them desirable for radiation detectors are discussed.

  15. Influence of the tilting reflection mirror on the temperature and wind velocity retrieved by a polarizing atmospheric Michelson interferometer.

    Science.gov (United States)

    Zhang, Chunmin; Li, Ying

    2012-09-20

    The principles of a polarizing atmospheric Michelson interferometer are outlined. The tilt of its reflection mirror results in deflection of the reflected beam and affects the intensities of the observed inteferogram. This effect is systematically analyzed. Both rectangular and circular apertures are considered. The theoretical expression of the modulation depth and phase of the interferogram are derived. These parameters vary with the inclination angle of the mirror and the distance between the deflection center and the optical axis and significantly influence the retrieved temperature and wind speed. If the wind and temperature errors are required to be less than 3 m/s and 5 K, the deflection angle must be less than 0.5°. The errors are also dependent on the shape of aperture. If the reflection mirror is deflected in one direction, the temperature error is smaller for a circular aperture (1.3 K) than for a rectangular one (2.6 K), but the wind velocity errors are almost the same (less than 3 m/s). If the deflection center and incident light beam are coincident, the temperature errors are 3 × 10(-4) K and 0.45 K for circular and rectangular apertures, respectively. The wind velocity errors are 1.2 × 10(-3) m/s and 0.06 m/s. Both are small. The result would be helpful for theoretical research and development of the static polarization wind imaging interferometer.

  16. EFFECT OF WATER CONTENT, TEMPERATURE AND AVERAGE DROPLET SIZE ON THE SETTLING VELOCITY OF WATER-IN-OIL EMULSIONS

    Directory of Open Access Journals (Sweden)

    W. J. Souza

    2015-06-01

    Full Text Available AbstractWater-in-oil (W/O emulsions are complex mixtures generally found in crude oil production in reservoirs and processing equipment. Sedimentation studies of water-oil emulsions enable the analysis of the fluid dynamic behavior concerning separation of this system composed of two immiscible liquids. Gravitational settling was evaluated in this article for a model emulsion system consisting of water and a Brazilian crude oil diluted in a clear mineral oil as organic phase. The effects of water content and temperature were considered in the study of sedimentation velocity of water-oil emulsions. Water contents between 10% and 50 % and temperatures of 25, 40 and 60 ºC were evaluated, and a Richardson-Zaki type correlation was obtained to calculate settling velocities as a function of the process variables investigated. Water contents and average droplet sizes were monitored at different levels in the settling equipment, thus enabling identification of the effect of these variables on the phenomena of sedimentation and coalescence of the emulsions studied. The results showed that the emulsion stability during sedimentation was governed by the emulsion water content, which yielded high settling velocities at low water contents, even when very small droplets were present. A quantitative analysis of the combined effects of drop size and droplet concentration supports the conclusion that a stronger effect is produced by the higher concentration of particles, compared with the relatively smaller effect of increasing the size of the droplets.

  17. Numerical investigation of velocity slip and temperature jump effects on unsteady flow over a stretching permeable surface

    Science.gov (United States)

    Hosseini, E.; Loghmani, G. B.; Heydari, M.; Rashidi, M. M.

    2017-02-01

    In this paper, the boundary layer flow and heat transfer of unsteady flow over a porous accelerating stretching surface in the presence of the velocity slip and temperature jump effects are investigated numerically. A new effective collocation method based on rational Bernstein functions is applied to solve the governing system of nonlinear ordinary differential equations. This method solves the problem on the semi-infinite domain without truncating or transforming it to a finite domain. In addition, the presented method reduces the solution of the problem to the solution of a system of algebraic equations. Graphical and tabular results are presented to investigate the influence of the unsteadiness parameter A , Prandtl number Pr, suction parameter fw, velocity slip parameter γ and thermal slip parameter φ on the velocity and temperature profiles of the fluid. The numerical experiments are reported to show the accuracy and efficiency of the novel proposed computational procedure. Comparisons of present results are made with those obtained by previous works and show excellent agreement.

  18. Design of shell-and-tube heat exchangers when the fouling depends on local temperature and velocity

    Energy Technology Data Exchange (ETDEWEB)

    Butterworth, D. [HTFS, Hyprotech, Didcot (United Kingdom)

    2002-07-01

    Shell-and-tube heat exchangers are normally designed on the basis of a uniform and constant fouling resistance that is specified in advance by the exchanger user. The design process is then one of determining the best exchanger that will achieve the thermal duty within the specified pressure drop constraints. It has been shown in previous papers [Designing shell-and-tube heat exchangers with velocity-dependant fouling, 34th US national Heat Transfer Conference, 20-22 August 2000, Pittsburg, PA; Designing shell-and-tube heat exchangers with velocity-dependant fouling, 2nd Int. Conf. on Petroleum and Gas Phase Behavior and Fouling, 27-31 August 2000, Copenhagen] that this approach can be extended to the design of exchangers where the design fouling resistance depends on velocity. The current paper briefly reviews the main findings of the previous papers and goes on to treat the case where the fouling depends also on the local temperatures. The Ebert-Panchal [Analysis of Exxon crude-oil, slip-stream coking data, Engineering Foundation Conference on Fouling Mitigation of Heat Exchangers, 18-23 June 1995, California] form of fouling rate equation is used to evaluate this fouling dependence. When allowing for temperature effects, it becomes difficult to divorce the design from the way the exchanger will be operated up to the point when the design fouling is achieved. However, rational ways of separating the design from the operation are proposed. (author)

  19. Meson spectral functions at finite temperature and isospin density with the functional renormalization group

    Science.gov (United States)

    Wang, Ziyue; Zhuang, Pengfei

    2017-07-01

    The pion superfluid and the corresponding Goldstone and soft modes are investigated in a two-flavor quark-meson model with a functional renormalization group. By solving the flow equations for the effective potential and the meson two-point functions at finite temperature and isospin density, the critical temperature for the superfluid increases sizeably in comparison with solving the flow equation for the potential only. The spectral function for the soft mode shows clearly a transition from meson gas to quark gas with increasing temperature and a crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer pairing of quarks with increasing isospin density.

  20. Molecular dissociation and shock-induced cooling in fluid nitrogen at high densities and temperatures

    Science.gov (United States)

    Radousky, H. B.; Nellis, W. J.; Ross, M.; Hamilton, D. C.; Mitchell, A. C.

    1986-01-01

    Radiative temperatures and electrical conductivities were measured for fluid nitrogen compressed dynamically to pressures of 18-90 GPa, temperatures of 4000-14,000 K, and densities of 2-3 g/cu cm. The data show a continuous phase transition above 30 GPa shock pressure and confirm that (delta-P/delta-T)v is less than 0, as indicated previously by Hugoniot equation-of-state experiments. The first observation of shock-induced cooling is also reported. The data are interpreted in terms of molecular dissociation, and the concentration of dissociated molecules is calculated as a function of density and temperature.

  1. Temperature and population density effects on locomotor activity of Musca domestica (Diptera: Muscidae).

    Science.gov (United States)

    Schou, T M; Faurby, S; Kjærsgaard, A; Pertoldi, C; Loeschcke, V; Hald, B; Bahrndorff, S

    2013-12-01

    The behavior of ectotherm organisms is affected by both abiotic and biotic factors. However, a limited number of studies have investigated the synergistic effects on behavioral traits. This study examined the effect of temperature and density on locomotor activity of Musca domestica (L.). Locomotor activity was measured for both sexes and at four densities (with mixed sexes) during a full light and dark (L:D) cycle at temperatures ranging from 10 to 40°C. Locomotor activity during daytime increased with temperature at all densities until reaching 30°C and then decreased. High-density treatments significantly reduced the locomotor activity per fly, except at 15°C. For both sexes, daytime activity also increased with temperature until reaching 30 and 35°C for males and females, respectively, and thereafter decreased. Furthermore, males showed a significantly higher and more predictable locomotor activity than females. During nighttime, locomotor activity was considerably lower for all treatments. Altogether the results of the current study show that there is a significant interaction of temperature and density on daytime locomotor activity of M. domestica and that houseflies are likely to show significant changes in locomotor activity with change in temperature.

  2. Effective temperature and radial velocity of the small-amplitude Cepheid Polaris (alpha UMi) in 2015

    CERN Document Server

    Usenko, I A; Miroshnichenko, A S; Danford, S

    2016-01-01

    We present the results of an analysis of 21 spectra of alpha UMi (Polaris) obtained in September - December 2015. Frequency analysis shows an increase of the pulsation period up to 8.6 min in comparison to the 2007 observational set. The radial velocity amplitude comes to 4.16 km s^-1, and it approximately twice the one found in 2007. The average Teff = 6017 K, and it is close to the value determined for the 2001-2004 set. Therefore Polaris moves to the red edge of the Cepheid instability strip (CIS)

  3. Local and linear chemical reactivity response functions at finite temperature in density functional theory.

    Science.gov (United States)

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  4. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Franco-Pérez, Marco, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Ayers, Paul W., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Vela, Alberto, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México, D.F. 07360 (Mexico)

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  5. Modeled Seasonal Variations of Firn Density Induced by Steady State Surface Air Temperature Cycle

    Science.gov (United States)

    Jun, Li; Zwally, H. Jay; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Seasonal variations of firn density in ice-sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn. A recent high-resolution (mm scale) density profile, measured along a 181 m core from Antarctica, showed small-scale density variations with a clear seasonal cycle that apparently was not-related to seasonal variations in deposition or known near-surface processes (Gerland and others 1999). A recent model of surface elevation changes (Zwally and Li, submitted) produced a seasonal variation in firn densification, and explained the seasonal surface elevation changes observed by satellite radar altimeters. In this study, we apply our 1-D time-dependent numerical model of firn densification that includes a temperature-dependent formulation of firn densification based on laboratory measurements of grain growth. The model is driven by a steady-state seasonal surface temperature and a constant accumulation rate appropriate for the measured Antarctic ice core. The modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid-summer with the highest temperature history compress to the highest density, and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density. The initial amplitude of the seasonal difference of about 0.13 reduces to about 0.09 in five years and asymptotically to 0.92 at depth, which is consistent with the core measurements.

  6. Ion density and temperature profiles along (XGSM) and across (ZGSM) the magnetotail as observed by THEMIS, Geotail, and ARTEMIS

    Science.gov (United States)

    Artemyev, A. V.; Angelopoulos, V.; Hietala, H.; Runov, A.; Shinohara, I.

    2017-02-01

    Characteristics of the two-dimensional configuration of the magnetotail current sheet are important for modeling magnetotail motion/evolution and charged particle energization. Because of the magnetotail current sheet's dynamical nature, however, simultaneous plasma and magnetic field measurements at different radial distances are required to reveal this configuration. Simultaneous observations of the magnetotail current sheet from Time History of Events and Macroscale Interactions during Substorms (THEMIS) D (around 10RE downtail), Geotail (around 30RE downtail), and Acceleration, Reconnection, Turbulence and Electrodynamics of the Moons Interaction with the Sun (ARTEMIS) P1 (around 55RE downtail) are used to study distributions of plasma (ion) density and temperature along (Earth-Sun direction) and across (north-south direction) the magnetotail. Fourteen events (each including several current sheet crossings at different downtail distances) are studied. We demonstrate that the plasma temperature along and across the magnetotail varies more significantly than plasma density does. The temperature decrease from equatorial plane to current sheet boundaries is a major contributor to the cross-tail pressure balance. The Alfven velocity VA,B calculated at the current sheet boundaries increases significantly toward the Earth from 700 km/s at lunar orbit ˜55RE to 2200 km/s around ˜10RE downtail. The corresponding energy EA=mpVA,B2 (mp is the proton mass) is 4 times larger than the plasma temperature T0 in the magnetotail's equatorial plane, whereas the ratio EA/T0 is constant along the magnetotail. The plasma temperature T0 measured around lunar orbit in the magnetotail agrees well with the simultaneously measured energy of solar wind protons mpVSW2/2 (VSW is the solar wind speed).

  7. Density of biofuel in function of temperature; Densidade de biocombustiveis em funcao da temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Melina C.J.; Lopes, Afonso [Universidade Estadual Paulista Julio de Mesquita Filho (FCAV/UNESP), Jaboticabal, SP (Brazil). Fac. de Ciencias Agrarias e Veterinarias. Dept. de Engenharia Rural], email: melina_cais@yahoo.com.br; Camara, Felipe T. [Universidade Federal do Ceara (UFC), Cariri, CE (Brazil); Lima, Leomar P. [Instituto Federal do Triangulo Mineiro (IFTM), Uberlandia, MG (Brazil)

    2011-07-01

    Considering the oil a non-renewable natural resource, Biodiesel is an alternative fuel, the same being renewable, biodegradable and made from vegetable oil or residual transesterified with anhydrous alcohol in the presence of a catalyst. This study aimed to evaluate the density of biodiesel methyl filtered residual oil from the university cafeteria, biodiesel methyl filtered hydrogenated fat residual McDonald's and the density of the mixture of 50% of residual oil from the university cafeteria with 50% of hydrogenated fat residual McDonald's all a function of temperature (10 deg C to 70 deg C). The experiment was conducted at the Agricultural Engineering Department of UNESP-Jaboticabal, SP. Was used 3x13x7 factorial experimental design, which represent three types of biodiesel, 13 July and the temperatures of the mixtures. We conclude that the residual oil biodiesel university restaurant density was lower, while biodiesel from hydrogenated fat from McDonald's and the mixture had higher densities, but differ from each other. The diesel (B0) had the lowest density and Biodiesel (B100) the largest. The B0 and B5 blends did not differ regarding density, but differed from the mix B15, B25, B50, B75 and B100. For all the mixtures tested, with the increase of temperature decreased the density. (author)

  8. Temperature effects on wood anatomy, wood density, photosynthesis and biomass partitioning of Eucalyptus grandis seedlings.

    Science.gov (United States)

    Thomas, D S; Montagu, K D; Conroy, J P

    2007-02-01

    Wood density, a gross measure of wood mass relative to wood volume, is important in our understanding of stem volume growth, carbon sequestration and leaf water supply. Disproportionate changes in the ratio of wood mass to volume may occur at the level of the whole stem or the individual cell. In general, there is a positive relationship between temperature and wood density of eucalypts, although this relationship has broken down in recent years with wood density decreasing as global temperatures have risen. To determine the anatomical causes of the effects of temperature on wood density, Eucalyptus grandis W. Hill ex Maiden seedlings were grown in controlled-environment cabinets at constant temperatures from 10 to 35 degrees C. The 20% increase in wood density of E. grandis seedlings grown at the higher temperatures was variously related to a 40% reduction in lumen area of xylem vessels, a 10% reduction in the lumen area of fiber cells and a 10% increase in fiber cell wall thickness. The changes in cell wall characteristics could be considered analogous to changes in carbon supply. Lumen area of fiber cells declined because of reduced fiber cell expansion and increased fiber cell wall thickening. Fiber cell wall thickness was positively related to canopy CO2 assimilation rate (Ac), which increased 26-fold because of a 24-fold increase in leaf area and a doubling in leaf CO2 assimilation rate from minima at 10 and 35 degrees C to maxima at 25 and 30 degrees C. Increased Ac increased seedling volume, biomass and wood density; but increased wood density was also related to a shift in partitioning of seedling biomass from roots to stems as temperature increased.

  9. Simultaneous measurement of electron temperature and density by a line pair method in the RFP plasma

    Science.gov (United States)

    Watanabe, Masayuki; Shimizu, S.; Ogawa, H.; Shinohara, T.

    2009-11-01

    A line-pair-method has been applied for a simultaneous measurement of the electron temperature and density in ATRAS RFP plasma. Three helium spectrum lines (668nm, 706nm, 728nm) were measured during the discharge at the same time and the electron temperature and density is estimated by using a Collision-Radiation model. To get the signal of the helium impunity line from the RFP discharge, the RFP plasma in the hydrogen gas with a few mixed helium gas was formed. In the typical ATRAS RFP discharge of the plasma current of 60kA, the electron temperature was approximately 50-150 eV and the electron density is the order of 10^18 m-3. During the discharge, the change of the temperature and density are mutually related and this correlation was the almost reverse phase. The periodically change of the temperature and density were also observed. This change synchronizes with a periodically increase of the averaged toroidal magnetic field, which is caused by the toroidal rotation of the increase of the toroidal magnetic field. This rotation, which is deeply related with dynamo effect, makes the plasma energy lose and particles also diffuse toward the plasma edge. As a result, the recycling of the particle and energy are occurred at the same time.

  10. Characterization of evaporation rate, temperature, velocity and humidity fields in a cold chamber

    OpenAIRE

    LECOQ L.; Flick, D.; Plana Fattori, A.; Laguerre, O.

    2014-01-01

    3rd IIR International Conference on Sustainability and the Cold Chain, ICCC 2014, London, , 23-/06/2014 - 25/06/2014; International audience; In a food factory some pathogenic bacteria can grow even at low temperature, especially Listeria Monocytogenes which resists to temperature around 0°C. Currently, two ways are used to prevent bacterial growth; product treatment (pasteurization, pH decrease) and cleaning but it's not sufficient to eliminate all microorganisms. This work takes part of a f...

  11. Unsteady mixed convection flow from a slender cylinder due to impulsive change in wall velocity and temperature

    Directory of Open Access Journals (Sweden)

    Patil P.M.

    2013-01-01

    Full Text Available An unsteady mixed convection flow of a viscous incompressible fluid over a non-permeable linear stretching vertical slender cylinder is considered to investigate the combined effects of buoyancy force and thermal diffusion. It is assumed that the slender cylinder is in line with the flow. The unsteadiness in the flow and temperature fields is caused due to the impulsive change in the wall velocity and wall temperature of linearly stretching vertical slender cylinder. The effect of surface curvature is also taken into account, particularly for the applications as wire and fiber drawing where exact predictions are expected. The governing boundary layer equations are transformed into a non-dimensional form by a group of non-similar transformations. The resulting system of coupled non-linear partial differential equations is solved by an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical computations are performed to understand the physical situations of linear stretching surface for different values of parameters to display the velocity and temperature profiles graphically. The numerical results for the local skin-friction coefficient and local Nusselt number are also presented. Present results are compared with previously published work and are found to be in excellent agreement.

  12. Numerical Simulation of Transient Development of Flame, Temperature and Velocity under Reduced Gravity in a Methane Air Diffusion Flame

    Science.gov (United States)

    Bhowal, Arup Jyoti; Mandal, Bijan Kumar

    2017-02-01

    A methane air co flow diffusion flame has been numerically simulated with the help of an in-house developed code at normal gravity, 0.5 G, and 0.0001 G (microgravity) for the study of transient behavior of the flame in terms of flame shape, temperature profile and velocity (streamlines). The study indicates that lower is the gravity level, the higher is the time of early transience. The flame developments during transience are marked by the formation of a secondary flamelet at different heights above the primary flame at all gravity levels. The development of temperature profile at microgravity takes a much longer time to stabilize than the flame development. At normal gravity and 0.5 G gravity level, streamlines, during transience, show intermediate vortices which are finally replaced by recirculation of ambient air from the exit plane. At microgravity, neither any vortex nor any recirculation at any stage is observed. Centerline temperature plots, at all gravity levels during transience, demonstrate a secondary peak at some instants as a consequence of the secondary flamelet formation. The centerline velocity at microgravity decreases gradually during transience, unlike at other two gravity levels where the fall is very sharp and is indicative of negligible buoyancy at microgravity.

  13. Techniques for Surface-Temperature Measurements and Transition Detection on Projectiles at Hypersonic Velocities--Status Report No. 2

    Science.gov (United States)

    Bogdanoff, D. W.; Wilder, M. C.

    2006-01-01

    The latest developments in a research effort to advance techniques for measuring surface temperatures and heat fluxes and determining transition locations on projectiles in hypersonic free flight in a ballistic range are described. Spherical and hemispherical titanium projectiles were launched at muzzle velocities of 4.6-5.8 km/sec into air and nitrogen at pressures of 95-380 Torr. Hemisphere models with diameters of 2.22 cm had maximum pitch and yaw angles of 5.5-8 degrees and 4.7-7 degrees, depending on whether they were launched using an evacuated launch tube or not. Hemisphere models with diameters of 2.86 cm had maximum pitch and yaw angles of 2.0-2.5 degrees. Three intensified-charge-coupled-device (ICCD) cameras with wavelength sensitivity ranges of 480-870 nm (as well as one infrared camera with a wavelength sensitivity range of 3 to 5 microns), were used to obtain images of the projectiles in flight. Helium plumes were used to remove the radiating gas cap around the projectiles at the locations where ICCD camera images were taken. ICCD and infrared (IR) camera images of titanium hemisphere projectiles at velocities of 4.0-4.4 km/sec are presented as well as preliminary temperature data for these projectiles. Comparisons were made of normalized temperature data for shots at approx.190 Torr in air and nitrogen and with and without the launch tube evacuated. Shots into nitrogen had temperatures 6% lower than those into air. Evacuation of the launch tube was also found to lower the projectile temperatures by approx.6%.

  14. Spectroscopic measurement of ion temperature and ion velocity distributions in the flux-coil generated FRC

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, D.; Gota, H.; Hayashi, R.; Kiyashko, V.; Morehouse, M.; Primavera, S. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Bolte, N. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Marsili, P. [Department of Physics, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Roche, T. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Wessel, F. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2010-10-15

    One aim of the flux-coil generated field reversed configuration at Tri Alpha Energy (TAE) is to establish the plasma where the ion rotational energy is greater than the ion thermal energy. To verify this, an optical diagnostic was developed to simultaneously measure the Doppler velocity-shift and line-broadening using a 0.75 m, 1800 groves/mm, spectrometer. The output spectrum is magnified and imaged onto a 16-channel photomultiplier tube (PMT) array. The individual PMT outputs are coupled to high-gain, high-frequency, transimpedance amplifiers, providing fast-time response. The Doppler spectroscopy measurements, along with a survey spectrometer and photodiode-light detector, form a suite of diagnostics that provide insights into the time evolution of the plasma-ion distribution and current when accelerated by an azimuthal-electric field.

  15. Spectroscopic measurement of ion temperature and ion velocity distributions in the flux-coil generated FRC.

    Science.gov (United States)

    Gupta, D; Bolte, N; Gota, H; Hayashi, R; Kiyashko, V; Marsili, P; Morehouse, M; Primavera, S; Roche, T; Wessel, F

    2010-10-01

    One aim of the flux-coil generated field reversed configuration at Tri Alpha Energy (TAE) is to establish the plasma where the ion rotational energy is greater than the ion thermal energy. To verify this, an optical diagnostic was developed to simultaneously measure the Doppler velocity-shift and line-broadening using a 0.75 m, 1800 groves/mm, spectrometer. The output spectrum is magnified and imaged onto a 16-channel photomultiplier tube (PMT) array. The individual PMT outputs are coupled to high-gain, high-frequency, transimpedance amplifiers, providing fast-time response. The Doppler spectroscopy measurements, along with a survey spectrometer and photodiode-light detector, form a suite of diagnostics that provide insights into the time evolution of the plasma-ion distribution and current when accelerated by an azimuthal-electric field.

  16. Spin-polarized versus chiral condensate in quark matter at finite temperature and density

    DEFF Research Database (Denmark)

    Matsuoka, Hiroaki; Tsue, Yasuhiko; da Providencia, Joao

    2016-01-01

    It is shown that the spin-polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasiniotype model as a low-energy effective theory of quantum chromodynamics. It is indicated within this low-energy ef......It is shown that the spin-polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasiniotype model as a low-energy effective theory of quantum chromodynamics. It is indicated within this low......-energy effective model that the chiral symmetry is broken again by the spin-polarized condensate on increasing the quark number density, while chiral symmetry restoration occurs, in which the chiral condensate disappears at a certain density....

  17. Charge density deposited in silicon by high velocity heavy ions. Densite de charges deposees par des ions lourds a haute vitesse dans le silicium

    Energy Technology Data Exchange (ETDEWEB)

    Vidiella, G.; Patin, Y. (CEA Centre d' Etudes de Bruyeres-le-Chatel, 91 (FR)); Touati, A. (Institut Curie, 75 - Paris (FR))

    1989-12-01

    For high velocity collisions, Doubly Differential Cross Sections for target ionisation (the main primary process), are well described by a recent refined theory. This allows ab initio calculation of the structure of the energy deposition in the incident ion track. Such a calculation first developed for radiobiological purpose has been applied to the case of a silicium target. Charge density profiles for various ions are presented here.

  18. Asymmetry energy of nuclear matter: Temperature and density dependence, and validity of semi-empirical formula

    CERN Document Server

    Bordbar, G H; Taghizade, M

    2015-01-01

    In this work, we have done a completely microscopic calculation using a many-body variational method based on the cluster expansion of energy to compute the asymmetry energy of nuclear matter. In our calculations, we have employed the $AV_{18}$ nuclear potential. We have also investigated the temperature and density dependence of asymmetry energy. Our results show that the asymmetry energy of nuclear matter depends on both density and temperature. We have also studied the effects of different terms in the asymmetry energy of nuclear matter. These investigations indicate that at different densities and temperatures, the contribution of parabolic term is very substantial with respect to the other terms. Therefore, we can conclude that the parabolic approximation is a relatively good estimation, and our calculated binding energy of asymmetric nuclear matter is in a relatively good agreement with that of semi-empirical mass formula. However, for the accurate calculations, it is better to consider the effects of o...

  19. High thermal power density heat transfer apparatus providing electrical isolation at high temperature using heat pipes

    Science.gov (United States)

    Morris, J. F. (Inventor)

    1985-01-01

    This invention is directed to transferring heat from an extremely high temperature source to an electrically isolated lower temperature receiver. The invention is particularly concerned with supplying thermal power to a thermionic converter from a nuclear reactor with electric isolation. Heat from a high temperature heat pipe is transferred through a vacuum or a gap filled with electrically nonconducting gas to a cooler heat pipe. If the receiver requires gratr thermal power density, geometries are used with larger heat pipe areas for transmitting and receiving energy than the area for conducting the heat to the thermionic converter. In this way the heat pipe capability for increasing thermal power densities compensates for the comparative low thermal power densities through the electrically nonconducting gap between the two heat pipes.

  20. Electron number density and temperature measurements in laser produced brass plasma

    Science.gov (United States)

    Shaltout, A. A.; Mostafa, N. Y.; Abdel-Aal, M. S.; Shaban, H. A.

    2010-04-01

    Laser-induced breakdown spectroscopy (LIBS) has been used for brass plasma diagnostic using a Nd:YAG laser at 1064 nm. Optimal experimental conditions were evaluated, including repetition rate, number of laser shots on sample, and laser energy. The plasma temperatures and the electron number densities were determined from the emission spectra of LIBS. Cu and Zn spectral lines were used for excitation temperature calculation using Saha-Boltzmann distribution as well as line pair ratio. It was found that, the excitation temperature calculated by using Saha-Boltzmann distribution and line pair ratio methods are not the same. The electron number density has been evaluated from the Stark broadening of Hα transition at 656.27 nm and the calculated electron number density is agreement with literature.

  1. Density, porosity, mineralogy, and internal structure of cosmic dust and alteration of its properties during high velocity atmospheric entry

    CERN Document Server

    Kohout, T; Suuronen, J -P; Rochette, P; Hutzler, A; Gattacceca, J; Skála, D D Badjukov R; Böhmová, V; Čuda, J

    2014-01-01

    X-ray microtomography (XMT), X-ray diffraction (XRD) and magnetic hysteresis measurements were used to determine micrometeorite internal structure, mineralogy, crystallography, and physical properties at ~{\\mu}m resolution. The study samples include unmelted, partially melted (scoriaceous) and completely melted (cosmic spherules) micrometeorites. This variety not only allows comparison of the mineralogy and porosity of these three micrometeorite types, but also reveals changes in meteoroid properties during atmospheric entry at various velocities. At low entry velocities, meteoroids do not melt, and their physical properties do not change. The porosity of unmelted micrometeorites varies considerably (0-12%) with one friable example having porosity around 50%. At higher velocities, the range of meteoroid porosity narrows, but average porosity increases (to 16-27%) due to volatile evaporation and partial melting (scoriaceous phase). Metal distribution seems to be mostly unaffected at this stage. At even higher ...

  2. The Numerical Investigation of Temperature and Velocity Distribution in the High-Bay Depot

    Directory of Open Access Journals (Sweden)

    Xuehong Wu

    2014-07-01

    Full Text Available High-bay depot plays an important role in the storage industry. Due to large and high space of high-bay depot, it is difficult to make temperature distribution uniform, which will influence the storage time of raw materials. In this paper, the aim is to find the reasonable air supply and energy-saving method; a supply-air method of high-bay depot is investigated as an example. The results show the radius and spacing of the supply-air inlet have great influence on temperature distribution. The temperature nonuniformity coefficient of summer is smaller than that of winter. The investigated results can provide a theoretical reference for the high-bay depot design and economic operation.

  3. A density-temperature description of the outer electron radiation belt during geomagnetic storms

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Cayton, Thomas E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Electron flux measurements from 7 satellites in geosynchronous orbit from 1990-2007 are fit with relativistic bi-Maxwellians, yielding a number density n and temperature T description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value ofn is 3.7x10-4 cm-3 and the median value ofT is 142 keY. General statistical properties of n, T, and the 1.1-1.5 MeV flux J are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis triggered on storm onset, the evolution of the outer electron radiation belt through high-speed-steam-driven storms is investigated. The number density decay during the calm before the storm is seen, relativistic-electron dropouts and recoveries from dropout are investigated, and the heating of the outer electron radiation belt during storms is examined. Using four different triggers (SSCs, southward-IMF CME sheaths, southward-IMF magnetic clouds, and minimum Dst), CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms an absence of a density decay prior to storm onset is found, the compression of the outer electron radiation belt at time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase is seen, and the increase in density and temperature during storm recovery phase is observed. Differences are found between the density-temperature and the flux descriptions, with more information for analysis being available in the density-temperature description.

  4. A density-temperature description of the outer electron radiation belt during geomagnetic storms

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Cayton, Thomas E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Electron flux measurements from 7 satellites in geosynchronous orbit from 1990-2007 are fit with relativistic bi-Maxwellians, yielding a number density n and temperature T description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value ofn is 3.7x10-4 cm-3 and the median value ofT is 142 keY. General statistical properties of n, T, and the 1.1-1.5 MeV flux J are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis triggered on storm onset, the evolution of the outer electron radiation belt through high-speed-steam-driven storms is investigated. The number density decay during the calm before the storm is seen, relativistic-electron dropouts and recoveries from dropout are investigated, and the heating of the outer electron radiation belt during storms is examined. Using four different triggers (SSCs, southward-IMF CME sheaths, southward-IMF magnetic clouds, and minimum Dst), CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms an absence of a density decay prior to storm onset is found, the compression of the outer electron radiation belt at time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase is seen, and the increase in density and temperature during storm recovery phase is observed. Differences are found between the density-temperature and the flux descriptions, with more information for analysis being available in the density-temperature description.

  5. Developments in lattice quantum chromodynamics for matter at high temperature and density

    Indian Academy of Sciences (India)

    Gert Aarts

    2015-05-01

    A brief overview of the QCD phase diagram at nonzero temperature and density is provided. It is explained why standard lattice QCD techniques are not immediately applicable for its determination, due to the sign problem. A selection of recent lattice approaches that attempt to evade the sign problem are then discussed and classified according to the underlying principle: constrained simulations (density of states, histograms), holomorphicity (complex Langevin, Lefschetz thimbles), partial summations (clusters, subsets, bags) and change in integration order (strong coupling, dual formulations).

  6. Simultaneously measuring thickness, density, velocity and attenuation of thin layers using V(z,t) data from time-resolved acoustic microscopy.

    Science.gov (United States)

    Chen, Jian; Bai, Xiaolong; Yang, Keji; Ju, Bing-Feng

    2015-02-01

    To meet the need of efficient, comprehensive and automatic characterization of the properties of thin layers, a nondestructive method using ultrasonic testing to simultaneously measure thickness, density, sound velocity and attenuation through V(z,t) data, recorded by time-resolved acoustic microscopy is proposed. The theoretical reflection spectrum of the thin layer at normal incidence is established as a function of three dimensionless parameters. The measured reflection spectrum R(θ,ω) is obtained from V(z,t) data and the measured thickness is derived from the signals when the lens is focused on the front and back surface of the thin layer, which are picked up from the V(z,t) data. The density, sound velocity and attenuation are then determined by the measured thickness and inverse algorithm utilizing least squares method to fit the theoretical and measured reflection spectrum at normal incidence. It has the capability of simultaneously measuring thickness, density, sound velocity and attenuation of thin layer in a single V(z,t) acquisition. An example is given for a thin plate immersed in water and the results are satisfactory. The method greatly simplifies the measurement apparatus and procedures, which improves the efficiency and automation for simultaneous measurement of basic mechanical and geometrical properties of thin layers.

  7. Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

    Energy Technology Data Exchange (ETDEWEB)

    Buzi, Luxherta, E-mail: l.buzi@fz-juelich.de [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Université de Lorraine, Institut Jean Lamour, CNRS UMR 7198, Bvd. des Aiguillettes, F-54506 Vandoeuvre (France); Temmerman, Greg De [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Unterberg, Bernhard; Reinhart, Michael; Litnovsky, Andrey; Philipps, Volker [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Oost, Guido Van [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Möller, Sören [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany)

    2014-12-15

    Systematic study of deuterium irradiation effects on tungsten was done under ITER – relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER – like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux densities (high: 3.5–7 · 10{sup 23} D{sup +}/m{sup 2} s and low: 9 · 10{sup 21} D{sup +}/m{sup 2} s). Particle fluence and ion energy, respectively 10{sup 26} D{sup +}/m{sup 2} and ∼38 eV were kept constant in all cases. The experiments were performed at three different surface temperatures 530 K, 630 K and 870 K. Experimental results concerning the deuterium retention and surface modifications of low flux exposure confirmed previous investigations. At temperatures 530 K and 630 K, deuterium retention was higher at lower flux density due to the longer exposure time (steady state plasma operation) and a consequently deeper diffusion range. At 870 K, deuterium retention was found to be higher at high flux density according to the thermal desorption spectroscopy (TDS) measurements. While blisters were completely absent at low flux density, small blisters of about 40–50 nm were formed at high flux density exposure. At the given conditions, a relation between deuterium retention and blister formation has been found which has to be considered in addition to deuterium trapping in defects populated by diffusion.

  8. $\\Delta$ self-energy at finite temperature and density and the $\\pi N$ cross-section

    CERN Document Server

    Ghosh, Snigdha; Sarkar, Sourav

    2016-01-01

    The self energy of $\\Delta$-baryon is evaluated at finite temperature and density using the real time formalism of thermal field theory. The Dyson-Schwinger equation is used to get the exact thermal propagator followed by the spectral function of $\\Delta$. The $\\pi N$ scattering cross section obtained using explicit $\\Delta$ exchange is normalized to the experimental data in vacuum and its medium modification is implemented by means of the exact thermal propagator. A significant suppression of the peak is observed at higher temperature and baryon density.

  9. Growth, temperature and density relationships of North Sea cod ( Gadus morhua )

    DEFF Research Database (Denmark)

    Rindorf, Anna; Jensen, Henrik; Schrum, Corinna

    2008-01-01

    This study presents an analysis of the relationship between ambient temperature, cod density, fishing mortality, prey fish biomass, and growth of North Sea cod (Gadus morhua) as estimated from survey catches during the period from 1983 to 2006. Growth of young cod was positively related to temper......This study presents an analysis of the relationship between ambient temperature, cod density, fishing mortality, prey fish biomass, and growth of North Sea cod (Gadus morhua) as estimated from survey catches during the period from 1983 to 2006. Growth of young cod was positively related...

  10. Ion temperature gradient driven mode in presence of transverse velocity shear in magnetized plasmas

    DEFF Research Database (Denmark)

    Chakrabarti, N.; Juul Rasmussen, J.; Michelsen, Poul

    2005-01-01

    The effect of sheared poloidal flow on the toroidal branch of the ion temperature gradient driven mode of magnetized nonuniform plasma is studied. A novel "nonmodal" calculation is used to analyze the problem. It is shown that the transverse shear flow considerably reduced the growth...

  11. Analytical solution for peristaltic flow of conducting nanofluids in an asymmetric channel with slip effect of velocity, temperature and concentration

    Directory of Open Access Journals (Sweden)

    S. Sreenadh

    2016-06-01

    Full Text Available The Peristaltic transport of conducting nanofluids under the effect of slip condition in an asymmetric channel is reported in the present work. The mathematical modelling has been carried out under long wavelength and low Reynolds number approximations. The analytical solutions are obtained for pressure rise, nanoparticle concentration, temperature distribution, velocity profiles and stream function. Influence of various parameters on the flow characteristics has been discussed with the help of graphs. The results showed that the pressure rise increases with increasing magnetic effect and decreases with increasing slip parameter. The effects of thermophoresis parameter and Brownian motion parameter on the nanoparticle concentration and temperature distribution are studied. It is observed that the pressure gradient increases with increasing slip parameter and magnetic effect. The trapping phenomenon for different parameters is presented.

  12. NUMERICAL MODELLING OF VELOCITY AND TEMPERATURE DISTRIBUTIONS OF THE BUOYANCY CONVECTION EFFECT IN KNbO3 MELT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Numerical modelling of velocity and temperature fields in high-temperature KNbO3 melt of a loop-shaped Pt wire heater is carried out by using the commercial com putational code ANSYS for the mathematical solution of the governing equations.Based on the experimental boundary conditions and the Boussinesq approximation,the numerical modelling of a steady and two-dimensional model is applied to study the process under consideration of the buoyancy-driven convection condition. The result is compared with the previous experimental and theoretical data obtained in our laboratory, and the former is in agreement with the latter. Thus a theoretical guide for reasonable growth conditions is provided by studying in depth the real fluid flow effects in the crystal growth from the melt.

  13. Feasibility Study of Velocity and Temperature Measurements of an Arcjet Flow using Laser Resonance Doppler Velocimetric (LRDV) Technique

    Science.gov (United States)

    Rob, Mohammad A.

    1996-01-01

    Thermal Protection System (TPS) materials are used in space vehicles to shield from high heating environment encountered during their atmospheric reentry. Arcjet wind tunnels are used to simulate the flowfield encountered by the spacecrafts, and are used for testing TPS materials. How well these tests simulate the actual heating environment encountered by space vehicles depends on the characteristics of the simulated flow. The flow characterization requires the determination of temperature, concentration, and velocity of the various atomic and molecular species present in the flow. However, determining these parameters requires a complex set of both analytical and experimental procedures. The ability to properly simulate the flight environment is directly related to the accuracy with which these techniques can be used to define the arcjet Laser Resonance Doppler Velocimetric (LRDV) technique can be used to accurately determine the velocity and temperature of a gaseous species. In this technique, the medium is probed with a laser beam that is in resonance with an absorbing transition of the species. The absorption lineshape is Doppler-shifted due to the flow velocity of the species, and the frequency shift is detected as the variation in intensity of the fluorescence emitted by the species. Thus a measurement of the Doppler shift and the width of a spectral line can give both the temperature and the velocity of the flowfield. This summer, our project was to make a feasibility study to set up an experimental arrangement for the laser resonance Doppler velocimetric technique using a ring dye laser. Experiments required troubleshooting, cleaning, testing, and alignment of two lasers and several diagnostics instruments. All instruments and lasers necessary for the project worked well, but the output power of the broadband fundamental dye laser was limited to about 20 mW. This was quite low as compared to that necessary to obtain second harmonic oscillation at 327.49 nm

  14. Supersymmetry and R-symmetry Breaking in Meta-stable Vacua at Finite Temperature and Density

    CERN Document Server

    Arai, Masato; Sasaki, Shin

    2014-01-01

    We study a meta-stable supersymmetry-breaking vacuum in a generalized O'Raifeartaigh model at finite temperature and chemical potentials. Fields in the generalized O'Raifeartaigh model possess different R-charges to realize R-symmetry breaking. Accordingly, at finite density and temperature, the chemical potentials have to be introduced in a non-uniform way. Based on the formulation elaborated in our previous work we study the one-loop thermal effective potential including the chemical potentials in the generalized O'Raifeartaigh model. We perform the numerical analysis and find that the R-symmetry breaking vacua, which exist at zero temperature and zero chemical potential, are destabilized for some parameter regions. In addition, we find that there are parameter regions where new R-symmetry breaking vacua are realized even at high temperature by the finite density effects.

  15. The space density of primordial gas clouds near galaxies and groups and their relation to galactic high-velocity clouds

    NARCIS (Netherlands)

    Zwaan, MA; Briggs, FH

    2000-01-01

    The Arecibo H I Strip Survey probed the halos of similar to 300 cataloged galaxies and the environments of similar to 14 groups with sensitivity to neutral hydrogen masses greater than or equal to 10(7) M-circle dot. The survey detected no objects with properties resembling the high-velocity clouds

  16. Development of a new wire probe Dedicated to velocity and temperature measurement In mixed convection gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Jean-Paul Moro; Eric Hervieu [CEA/Grenoble - DER/SSTH/LIEX - 38054 Grenoble cedex 9 (France)

    2005-07-01

    Full text of publication follows: The aim of the COPPEC experimental program, performed at Atomic Energy Commission (CEA-Grenoble), is to build a reliable data base for improving and assessing single-phase Large Eddy Simulation thermal-hydraulic codes, in the field of turbulent flows with buoyancy forces. Experiments are carried out in an upward turbulent air flow established between vertical parallel plates maintained at different wall temperatures. The investigation concentrates on mixed convection flows, with Reynolds number ranging from 10{sup 3} to 6.10{sup 4} and Richardson number ranging from 10{sup -4} to 1. Hot wire anemometry and cold wire thermometry are used to measure respectively local velocity and temperature. Moreover, since both hot and cold wires are implemented on the same probe, Reynolds stress and turbulent heat flux can also be quantified. High bandwidth anemometry and thermometry require wires with a diameter of 1,2 {mu}m. Measurements of average and fluctuating flow quantities are performed in the vicinity of the heated wall, as close as 10 {mu}m corresponding to y{sup +} {approx} 0,1. At such a distance from the heated wall, the temperature gradient can reach 104 deg. C/m which, combined with the high temperature level, induces unwanted effects such as heat conduction in the prongs and thermoelectric effects at the junctions, leading to strong measurement bias. As a consequence, an original probe has been specifically developed, with insulating ceramic prongs and metallic coating. Moreover, because of very low velocities in the test section ({<=} 2 m/s), a particular calibration procedure had to be implemented, on a dedicated wind tunnel. At this moment, this new type of probe has been validated and we should obtain convincing results for measuring turbulence characteristics. (authors)

  17. Error estimations of dry deposition velocities of air pollutants using bulk sea surface temperature under common assumptions

    Science.gov (United States)

    Lan, Yung-Yao; Tsuang, Ben-Jei; Keenlyside, Noel; Wang, Shu-Lun; Arthur Chen, Chen-Tung; Wang, Bin-Jye; Liu, Tsun-Hsien

    2010-07-01

    It is well known that skin sea surface temperature (SSST) is different from bulk sea surface temperature (BSST) by a few tenths of a degree Celsius. However, the extent of the error associated with dry deposition (or uptake) estimation by using BSST is not well known. This study tries to conduct such an evaluation using the on-board observation data over the South China Sea in the summers of 2004 and 2006. It was found that when a warm layer occurred, the deposition velocities using BSST were underestimated within the range of 0.8-4.3%, and the absorbed sea surface heat flux was overestimated by 21 W m -2. In contrast, under cool skin only conditions, the deposition velocities using BSST were overestimated within the range of 0.5-2.0%, varying with pollutants and the absorbed sea surface heat flux was underestimated also by 21 W m -2. Scale analysis shows that for a slightly soluble gas (e.g., NO 2, NO and CO), the error in the solubility estimation using BSST is the major source of the error in dry deposition estimation. For a highly soluble gas (e.g., SO 2), the error in the estimation of turbulent heat fluxes and, consequently, aerodynamic resistance and gas-phase film resistance using BSST is the major source of the total error. In contrast, for a medium soluble gas (e.g., O 3 and CO 2) both the errors from the estimations of the solubility and aerodynamic resistance are important. In addition, deposition estimations using various assumptions are discussed. The largest uncertainty is from the parameterizations for chemical enhancement factors. Other important areas of uncertainty include: (1) various parameterizations for gas-transfer velocity; (2) neutral-atmosphere assumption; (3) using BSST as SST, and (4) constant pH value assumption.

  18. Model for seawater fouling and effects of temperature, flow velocity and surface free energy on seawater fouling☆

    Institute of Scientific and Technical Information of China (English)

    Dazhang Yang; Jianhua Liu; Xiaoxue E; Linlin Jiang

    2016-01-01

    A kinetic model was proposed to predict the seawater fouling process in the seawater heat exchangers. The new model adopted an expression combining depositional and removal behaviors for seawater fouling based on the Kern–Seaton model. The present model parameters include the integrated kinetic rate of deposition (kd) and the integrated kinetic rate of removal (kr), which have clear physical significance. A seawater-fouling monitoring de-vice was established to validate the model. The experimental data were wel fitted to the model, and the param-eters were obtained in different conditions. SEM and EDX analyses were performed after the experiments, and the results show that the main components of seawater fouling are magnesium hydroxide and aluminum hy-droxide. The effects of surface temperature, flow velocity and surface free energy were assessed by the model and the experimental data. The results indicate that the seawater fouling becomes aggravated as the surface tem-perature increased in a certain range, and the seawater fouling resistance reduced as the flow velocity of seawater increased. Furthermore, the effect of the surface free energy of metals was analyzed, showing that the lower sur-face free energy mitigates the seawater fouling accumulation.

  19. Phase change nanocomposites with tunable melting temperature and thermal energy storage density

    Science.gov (United States)

    Liu, Minglu; Wang, Robert Y.

    2013-07-01

    Size-dependent melting decouples melting temperature from chemical composition and provides a new design variable for phase change material applications. To demonstrate this potential, we create nanocomposites that exhibit stable and tunable melting temperatures through numerous melt-freeze cycles. These composites consist of a monodisperse ensemble of Bi nanoparticles (NPs) embedded in a polyimide (PI) resin matrix. The Bi NPs operate as the phase change component whereas the PI resin matrix prevents nanoparticle coalescence during melt-freeze cycles. We tune melting temperature and enthalpy of fusion in these composites by varying the NP diameter. Adjusting the NP volume fraction also controls the composite's thermal energy storage density. Hence it is possible to leverage size effects to tune phase change temperature and energy density in phase change materials.Size-dependent melting decouples melting temperature from chemical composition and provides a new design variable for phase change material applications. To demonstrate this potential, we create nanocomposites that exhibit stable and tunable melting temperatures through numerous melt-freeze cycles. These composites consist of a monodisperse ensemble of Bi nanoparticles (NPs) embedded in a polyimide (PI) resin matrix. The Bi NPs operate as the phase change component whereas the PI resin matrix prevents nanoparticle coalescence during melt-freeze cycles. We tune melting temperature and enthalpy of fusion in these composites by varying the NP diameter. Adjusting the NP volume fraction also controls the composite's thermal energy storage density. Hence it is possible to leverage size effects to tune phase change temperature and energy density in phase change materials. Electronic supplementary information (ESI) available: Experimental details and additional DSC data on nanocomposites and pure PI resin. See DOI: 10.1039/c3nr02842a

  20. Finite Temperature and Density Effects in Higher Dimensions with and without Compactifications

    CERN Document Server

    Shiraishi, Kiyoshi

    2012-01-01

    Expressions for the thermodynamic potential of a Dirac fermion gas are represented at finite temperature with the chemical potential in an ultrastatic space $R^d\\times S^N$. The high- and low- temperature expansions for the thermodynamic potential are obtained and, in particular, strongly degenerate fermi gas is investigated. For the Candelas-Weinberg model, sufficiently high "charge" density prevents the compactification of the extra space.

  1. Temperature and quark density effects on the chiral condensate: an AdS/QCD study

    Energy Technology Data Exchange (ETDEWEB)

    Colangelo, P. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Bari (Italy); Giannuzzi, F.; Nicotri, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Bari (Italy); Universita degli Studi di Bari, Dipartimento di Fisica, Bari (Italy); Tangorra, V. [Universita degli Studi di Bari, Dipartimento di Fisica, Bari (Italy)

    2012-08-15

    We investigate the dependence of the chiral condensate left angle anti qq right angle on the temperature and quark density using the soft-wall holographic model of QCD, adopting geometries with black holes at finite temperature and quark chemical potential {mu}. We find that, for {mu} below a critical value, increasing the temperature the condensate decreases and vanishes at a temperature T{approx_equal}210{proportional_to} MeV (at {mu}=0). An analogous behaviour is observed increasing the chemical potential at fixed temperature. These results agree with the findings obtained by other methods. We also comment on the robustness of the results if geometries not involving black holes are adopted at low temperature, and an Hawking-Page transition is implemented. (orig.)

  2. Intrinsic temperature-dependent evolutions in the electron-boson spectral density obtained from optical data

    Science.gov (United States)

    Hwang, Jungseek

    2016-03-01

    We investigate temperature smearing effects on the electron-boson spectral density function (I2χ(ω)) obtained from optical data using a maximum entropy inversion method. We start with two simple model input I2χ(ω), calculate the optical scattering rates at selected temperatures using the model input spectral density functions and a generalized Allen’s formula, then extract back I2χ(ω) at each temperature from the calculated optical scattering rate using the maximum entropy method (MEM) which has been used for analysis of optical data of high-temperature superconductors including cuprates, and finally compare the resulting I2χ(ω) with the input ones. From this approach we find that the inversion process can recover the input I2χ(ω) almost perfectly when the quality of fits is good enough and also temperature smearing (or thermal broadening) effects appear in the I2χ(ω) when the quality of fits is not good enough. We found that the coupling constant and the logarithmically averaged frequency are robust to the temperature smearing effects and/or the quality of fits. We use these robust properties of the two quantities as criterions to check whether experimental data have intrinsic temperature-dependent evolutions or not. We carefully apply the MEM to two material systems (one optimally doped and the other underdoped cuprates) and conclude that the I2χ(ω) extracted from the optical data contain intrinsic temperature-dependent evolutions.

  3. Data Report. Volume II. Velocity and Temperature Profile Data for Accelerating, Transitional Boundary Layers.

    Science.gov (United States)

    1981-01-01

    CELTA ’ INTEGPAL = -.46312 -. 43524 CLAUSEPS ’G’ INTEGRAL : 5.b0813 3.11775 DISPLACEMENT THICKNESS - CONST6NT DENSITY : .029C9 .C2426 0OMENTUM...FE (FEX) = 4C~n :NCLT VALLr CF ELCCITY CELTA = 1C- jLtJLT vALLE CF TEP j r’,TLK r E LT A:=2 C tLCLLATEC, (ELT A= E’ E~i L ;E’ I f.P U 7 16 CiL C...5 FLYNCLr, KLvEL~ R E X) Z 7Z457Q.6C 1t\\PLI VALL’ CF E L(CCITy C E L T t 1’L I AL LE CF TE f T LRF-’ VL T P C!LCLLA1En CELTA = [JSL4C-.1’FK1 THIC$ ES

  4. High-resolution spectroscopy diagnostics for measuring impurity ion temperature and velocity on the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Weinzettl, Vladimir, E-mail: vwei@ipp.cas.cz [Institute of Plasma Physics ASCR, Prague (Czech Republic); Shukla, Gaurav [Institute of Plasma Physics ASCR, Prague (Czech Republic); Department of Applied Physics, Ghent University, Ghent (Belgium); Faculty of Mathematics and Physics, Charles University in Prague, Prague (Czech Republic); Ghosh, Joydeep [Institute for Plasma Research, Bhat, Gandhinagar (India); Melich, Radek; Panek, Radomir [Institute of Plasma Physics ASCR, Prague (Czech Republic); Tomes, Matej; Imrisek, Martin; Naydenkova, Diana [Institute of Plasma Physics ASCR, Prague (Czech Republic); Faculty of Mathematics and Physics, Charles University in Prague, Prague (Czech Republic); Varju, Josef [Institute of Plasma Physics ASCR, Prague (Czech Republic); Pereira, Tiago [Instituto de Plasmas e Fusão Nuclear, Lisboa (Portugal); Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Gomes, Rui [Instituto de Plasmas e Fusão Nuclear, Lisboa (Portugal); Abramovic, Ivana; Jaspers, Roger [Eindhoven University of Technology, Eindhoven (Netherlands); Pisarik, Michael [SQS Vlaknova optika a.s., Nova Paka (Czech Republic); Department of Electromagnetic Field, Faculty of Electrical Engineering, Czech Technical University in Prague (Czech Republic); Odstrcil, Tomas [Max-Planck-Institut fur Plasmaphysik, Garching (Germany); Van Oost, Guido [Department of Applied Physics, Ghent University, Ghent (Belgium)

    2015-10-15

    Highlights: • We built a new diagnostic of poloidal plasma rotation on the COMPASS tokamak. • Improvements in throughput via toroidal integration and fiber optimizations shown. • Poloidal rotation and ion temperature measured in L- and H-mode and during RMP. • Design and parameters of a new CXRS diagnostic for COMPASS are introduced. - Abstract: High-resolution spectroscopy is a powerful tool for the measurement of plasma rotation as well as ion temperature using the Doppler shift of the emitted spectral lines and their Doppler broadening, respectively. Both passive and active diagnostic variants for the COMPASS tokamak are introduced. The passive diagnostic focused on the C III lines at about 465 nm is utilized for the observation of the poloidal plasma rotation. The current set-up of the measuring system is described, including the intended high-throughput optics upgrade. Different options to increase the fiber collection area are mentioned, including a flower-like fiber bundle, and the use of micro-lenses or tapered fibers. Recent measurements of poloidal plasma rotation of the order of 0–6 km/s are shown. The design of the new active diagnostic using a deuterium heating beam and based on charge exchange recombination spectroscopy (C VI line at 529 nm) is introduced. The tool will provide both space (0.5–5 cm) and time (10 ms) resolved toroidal plasma rotation and ion temperature profiles. The results of the Simulation of Spectra code used to examine the feasibility of charge exchange measurements on COMPASS are shown and connected with a selection of the spectrometer coupled with the CCD camera.

  5. Modeling lower critical solution temperature behavior of associating polymer brushes with classical density functional theory.

    Science.gov (United States)

    Gong, Kai; Marshall, Bennett D; Chapman, Walter G

    2013-09-07

    We study the lower critical solution temperature (LCST) behavior of associating polymer brushes (i.e., poly(N-isopropylacrylamide)) using classical density functional theory. Without using any empirical or temperature-dependent parameters, we find the phase transition of polymer brushes from extended to collapsed structure with increasing temperature, indicating the LCST behavior of polymer brushes. The LCST behavior of associating polymer brushes is attributed to the interplay of hydrogen bonding interactions and Lennard-Jones attractions in the system. The effect of grafting density and molecular weight on the phase behavior of associating polymer brushes has been also investigated. We find no LCST behavior at low grafting density or molecular weight. Moreover, increasing grafting density decreases the LCST and swelling ratio of polymer brushes. Similarly, increasing molecular weight decreases the LCST but increases the swelling ratio. At very high grafting density, a partial collapsed structure appears near the LCST. Qualitatively consistent with experiments, our results provide insight into the molecular mechanism of LCST behavior of associating polymer brushes.

  6. Electron density and electron temperature measurements in nanosecond pulse discharges over liquid water surface

    Science.gov (United States)

    Simeni Simeni, M.; Roettgen, A.; Petrishchev, V.; Frederickson, K.; Adamovich, I. V.

    2016-12-01

    Time-resolved electron density, electron temperature, and gas temperature in nanosecond pulse discharges in helium and O2-He mixtures near liquid water surface are measured using Thomson/pure rotational Raman scattering, in two different geometries, (a) ‘diffuse filament’ discharge between a spherical high-voltage electrode and a grounded pin electrode placed in a reservoir filled with distilled water, with the tip exposed, and (b) dielectric barrier discharge between the high-voltage electrode and the liquid water surface. A diffuse plasma filament generated between the electrodes in helium during the primary discharge pulse exhibits noticeable constriction during the secondary discharge pulse several hundred ns later. Adding oxygen to the mixture reduces the plasma filament diameter and enhances constriction during the secondary pulse. In the dielectric barrier discharge, diffuse volumetric plasma occupies nearly the entire space between the high voltage electrode and the liquid surface, and extends radially along the surface. In the filament discharge in helium, adding water to the container results in considerable reduction of plasma lifetime compared to the discharge in dry helium, by about an order of magnitude, indicating rapid electron recombination with water cluster ions. Peak electron density during the pulse is also reduced, by about a factor of two, likely due to dissociative attachment to water vapor during the discharge pulse. These trends become more pronounced as oxygen is added to the mixture, which increases net rate of dissociative attachment. Gas temperature during the primary discharge pulse remains near room temperature, after which it increases up to T ~ 500 K over 5 µs and decays back to near room temperature before the next discharge pulse several tens of ms later. As expected, electron density and electron temperature in diffuse DBD plasmas are considerably lower compared to peak values in the filament discharge. Use of Thomson

  7. Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

    NARCIS (Netherlands)

    Buzi, L.; De Temmerman, G.; Unterberg, B.; M. Reinhart,; Litnovsky, A.; Philipps, V.; Van Oost, G.; Möller, S.

    2014-01-01

    Systematic study of deuterium irradiation effects on tungsten was done under ITER - relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER - like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux

  8. Investigation of the Critical Current Density of YBaCuO high-temperature Superconductor Ceramic

    OpenAIRE

    METSKHVARISHVILI, I. R.; KEKELIDZE, N. P.; METSKHVARISHVILI, M. R.

    2002-01-01

    The method of high harmonics is used to investigate penetration of low magnetic fields within the Y1Ba2Cu3O7 high-temperature superconductor ceramic. Given experimental results are explained by the modal dependencies between the value of critical current density and the magnetic induction B: jc(B) = jc(0){\\frac{{B02}} {{B02 + B2}}}.

  9. Electron density and temperature in NIO1 RF source operated in oxygen and argon

    Science.gov (United States)

    Barbisan, M.; Zaniol, B.; Cavenago, M.; Pasqualotto, R.; Serianni, G.; Zanini, M.

    2017-08-01

    The NIO1 experiment, built and operated at Consorzio RFX, hosts an RF negative ion source, from which it is possible to produce a beam of maximum 130 mA in H- ions, accelerated up to 60 kV. For the preliminary tests of the extraction system the source has been operated in oxygen, whose high electronegativity allows to reach useful levels of extracted beam current. The efficiency of negative ions extraction is strongly influenced by the electron density and temperature close to the Plasma Grid, i.e. the grid of the acceleration system which faces the source. To support the tests, these parameters have been measured by means of the Optical Emission Spectroscopy diagnostic. This technique has involved the use of an oxygen-argon mixture to produce the plasma in the source. The intensities of specific Ar I and Ar II lines have been measured along lines of sight close to the Plasma Grid, and have been interpreted with the ADAS package to get the desired information. This work will describe the diagnostic hardware, the analysis method and the measured values of electron density and temperature, as function of the main source parameters (RF power, pressure, bias voltage and magnetic filter field). The main results show that not only electron density but also electron temperature increase with RF power; both decrease with increasing magnetic filter field. Variations of source pressure and plasma grid bias voltage appear to affect only electron temperature and electron density, respectively.

  10. Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade

    DEFF Research Database (Denmark)

    Horacek, J.; Adamek, J.; Müller, H.W.

    2010-01-01

    This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements of plasma density, potential and electron temperature in the edge plasma of tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate the credibility of the ball-pen probe. We demonstrate that floating poten...

  11. Dissociation and ionization equilibria of deuterium fluid over a wide range of temperatures and densities

    Energy Technology Data Exchange (ETDEWEB)

    Zaghloul, Mofreh R. [Department of Physics, College of Science, United Arab Emirates University, P.O. Box 15551, Al-Ain (United Arab Emirates)

    2015-06-15

    We investigate the dissociation and ionization equilibria of deuterium fluid over a wide range of temperatures and densities. The partition functions for molecular and atomic species are evaluated, in a statistical-mechanically consistent way, implementing recent developments in the literature and taking high-density effects into account. A new chemical model (free energy function) is introduced in which the fluid is considered as a mixture of diatomic molecules, atoms, ions, and free electrons. Intensive short range hard core repulsion is taken into account together with partial degeneracy of free electrons and Coulomb interactions among charged particles. Samples of computational results are presented as a set of isotherms for the degree of ionization, dissociated fraction of molecules, pressure, and specific internal energy for a wide range of densities and temperatures. Predictions from the present model calculations show an improved and sensible physical behavior compared to other results in the literature.

  12. Nuclear level density of even-even nuclei with temperature-dependent pairing energy

    Energy Technology Data Exchange (ETDEWEB)

    Dehghani, V.; Alavi, S.A. [University of Sistan and Baluchestan, Physics Department, Faculty of Sciences, Zahedan (Iran, Islamic Republic of)

    2016-10-15

    The influence of using a temperature-dependent pairing term on the back-shifted Fermi gas (BSFG) model of nuclear level density of some even-even nuclei has been investigated. We have chosen an approach to determine the adjustable parameters from theoretical calculations, directly. The exact Ginzburg-Landau (EGL) theory was used to determine the temperature-dependent pairing energy as back-shifted parameter of the BSFG model. The level density parameter of the BSFG model has been determined through the Thomas-Fermi approximation. The level densities of {sup 96}Mo, {sup 106,112}Cd, {sup 106,108}Pd, {sup 164}Dy, {sup 232}Th, {sup 238}U and heat capacities of {sup 96}Mo and {sup 164}Dy nuclei were calculated. Good agreement between theory and experiment was observed. (orig.)

  13. An Estimate of Solar Wind Density and Velocity Profiles in a Coronal Hole and a Coronal Streamer

    Science.gov (United States)

    Patzold, M.; Tsurutani, B. T.; Bird, M. K.

    1996-01-01

    Using the total electron content data obtained by the Ulysses Solar Corona Experiment (SCE) during the first solar conjunction in summer 1991, two data sets were selected, one associated with a coronal hole and the other associated with coronal streamer crossings. In order to determine coronal streamer density profiles, the electron content of the tracking passes embedded in a coronal streamer were corrected for the contributions from coronal hole densities.

  14. Feasibility of measuring density and temperature of laser produced plasmas using spectroscopic techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Edens, Aaron D.

    2008-09-01

    A wide variety of experiments on the Z-Beamlet laser involve the creation of laser produced plasmas. Having a direct measurement of the density and temperature of these plasma would an extremely useful tool, as understanding how these quantities evolve in space and time gives insight into the causes of changes in other physical processes, such as x-ray generation and opacity. We propose to investigate the possibility of diagnosing the density and temperature of laser-produced plasma using temporally and spatially resolved spectroscopic techniques that are similar to ones that have been successfully fielded on other systems. Various researchers have measured the density and temperature of laboratory plasmas by looking at the width and intensity ratio of various characteristic lines in gases such as nitrogen and hydrogen, as well as in plasmas produced off of solid targets such as zinc. The plasma conditions produce two major measurable effects on the characteristic spectral lines of that plasma. The 1st is the Stark broadening of an individual line, which depends on the electron density of the plasma, with higher densities leading to broader lines. The second effect is a change in the ratio of various lines in the plasma corresponding to different ionization states. By looking at the ratio of these lines, we can gain some understanding of the plasma ionization state and consequently its temperature (and ion density when coupled with the broadening measurement). The hotter a plasma is, the higher greater the intensity of lines corresponding to higher ionization states. We would like to investigate fielding a system on the Z-Beamlet laser chamber to spectroscopically study laser produced plasmas from different material targets.

  15. Sintering process and critical current density of low activation Mg11B2 superconductors from low temperature to high temperature

    Science.gov (United States)

    Cheng, Fang; Liu, Yongchang; Ma, Zongqing; Shahriar Al Hossain, Md; Somer, M.

    2016-08-01

    As the "low activation" superconductor, Mg11B2 has a potential application in superconducting coils for fusion reactor. In present work, the sintering process and critical current density of low activation Mg11B2 superconductors were systemically studied from low temperature to high temperature. It was found that the Jc and Hirr values of Mg11B2 bulks in present work are both obviously higher than that of those samples prepared in previous studies. Furthermore, the low-temperature sintered samples exhibit better Jc performance at high fields than the high-temperature sintered samples, due to strong grain boundaries pinning. On the other hand, the high-temperature sintered samples have higher Jc at low fields compared to low-temperature sintered samples, mainly owing to their better crystallinity and grain connectivity. The highest Jc value (2.20 ×105 A cm-2 at 20 K, self-field) is obtained in the Mg11B2 sample sintered at 850 °C for 45 min.

  16. Characteristics of temporal evolution of particle density and electron temperature in helicon discharge

    Science.gov (United States)

    Yang, Xiong; Cheng, Mousen; Guo, Dawei; Wang, Moge; Li, Xiaokang

    2017-10-01

    On the basis of considering electrochemical reactions and collision relations in detail, a direct numerical simulation model of a helicon plasma discharge with three-dimensional two-fluid equations was employed to study the characteristics of the temporal evolution of particle density and electron temperature. With the assumption of weak ionization, the Maxwell equations coupled with the plasma parameters were directly solved in the whole computational domain. All of the partial differential equations were solved by the finite element solver in COMSOL MultiphysicsTM with a fully coupled method. In this work, the numerical cases were calculated with an Ar working medium and a Shoji-type antenna. The numerical results indicate that there exist two distinct modes of temporal evolution of the electron and ground atom density, which can be explained by the ion pumping effect. The evolution of the electron temperature is controlled by two schemes: electromagnetic wave heating and particle collision cooling. The high RF power results in a high peak electron temperature while the high gas pressure leads to a low steady temperature. In addition, an OES experiment using nine Ar I lines was conducted using a modified CR model to verify the validity of the results by simulation, showing that the trends of temporal evolution of electron density and temperature are well consistent with the numerically simulated ones.

  17. Multispecies Density and Temperature Gradient Dependence of Quasilinear Particle and Energy Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    G. Rewoldt; R.V. Budny; W.M. Tang

    2004-08-09

    The variations of the normalized quasilinear particle and energy fluxes with artificial changes in the density and temperature gradients, as well as the variations of the linear growth rates and real frequencies, for ion temperature gradient and trapped-electron modes, are calculated. The quasilinear fluxes are normalized to the total energy flux, summed over all species. Here, realistic cases for tokamaks and spherical torii are considered which have two impurity species. For situations where there are substantial changes in the normalized fluxes, the ''diffusive approximation,'' in which the normalized fluxes are taken to be linear in the gradients, is seen to be inaccurate. Even in the case of small artificial changes in density or temperature gradients, changes in the fluxes of different species (''off-diagonal'') generally are significant, or even dominant, compared to those for the same species (''diagonal'').

  18. High temperature and current density induced degradation of multi-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Baoming; Haque, M. A., E-mail: mah37@psu.edu [Mechanical and Nuclear Engineering, The Pennsylvania State University, 314, Leonhard Building, University Park, Pennsylvania 16802 (United States); Mag-isa, Alexander E.; Kim, Jae-Hyun [Korea Institute of Machinery and Materials, 156 Gajungbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Lee, Hak-Joo [Korea Institute of Machinery and Materials, 156 Gajungbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Center for Advanced Meta-Materials (CAMM), 156 Gajungbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2015-10-19

    We present evidence of moderate current density, when accompanied with high temperature, promoting migration of foreign atoms on the surface of multi-layer graphene. Our in situ transmission electron microscope experiments show migration of silicon atoms at temperatures above 800 °C and current density around 4.2 × 10{sup 7} A/cm{sup 2}. Originating from the micro-machined silicon structures that clamp the freestanding specimen, the atoms are observed to react with the carbon atoms in the multi-layer graphene to produce silicon carbide at temperatures of 900–1000 °C. In the absence of electrical current, there is no migration of silicon and only pyrolysis of polymeric residue is observed.

  19. Equation of state density models for hydrocarbons in ultradeep reservoirs at extreme temperature and pressure conditions

    Science.gov (United States)

    Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.

    2013-10-01

    The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.

  20. Schlieren technique applied to the arc temperature measurement in a high energy density cutting torch

    Science.gov (United States)

    Prevosto, L.; Artana, G.; Mancinelli, B.; Kelly, H.

    2010-01-01

    Plasma temperature and radial density profiles of the plasma species in a high energy density cutting arc have been obtained by using a quantitative schlieren technique. A Z-type two-mirror schlieren system was used in this research. Due to its great sensibility such technique allows measuring plasma composition and temperature from the arc axis to the surrounding medium by processing the gray-level contrast values of digital schlieren images recorded at the observation plane for a given position of a transverse knife located at the exit focal plane of the system. The technique has provided a good visualization of the plasma flow emerging from the nozzle and its interactions with the surrounding medium and the anode. The obtained temperature values are in good agreement with those values previously obtained by the authors on the same torch using Langmuir probes.

  1. Computer simulations of the restricted primitive model at very low temperature and density.

    Science.gov (United States)

    Valeriani, Chantal; Camp, Philip J; Zwanikken, Jos W; van Roij, René; Dijkstra, Marjolein

    2010-03-17

    The problem of successfully simulating ionic fluids at low temperature and low density states is well known in the simulation literature: using conventional methods, the system is not able to equilibrate rapidly due to the presence of strongly associated cation-anion pairs. In this paper we present a numerical method for speeding up computer simulations of the restricted primitive model (RPM) at low temperatures (around the critical temperature) and at very low densities (down to 10(-10)σ(-3), where σ is the ion diameter). Experimentally, this regime corresponds to typical concentrations of electrolytes in nonaqueous solvents. As far as we are aware, this is the first time that the RPM has been equilibrated at such extremely low concentrations. More generally, this method could be used to equilibrate other systems that form aggregates at low concentrations.

  2. Vortex-lattice pinning and critical current density in anisotropic high-temperature superconductors

    Science.gov (United States)

    Li, Yingxu; Li, Xiangyu; Kang, Guozheng; Gao, Yuanwen

    2016-10-01

    The anisotropy of critical current density is an impressive manifestation in the physics of high-temperature superconductors. We develop an analytical characterization of anisotropic flux-lattice pinning and critical current density in a system of random point defects. The effect of superconducting anisotropy on the pinning force and critical current density is formulated. The in-plane/out-of-plane anisotropy and microscopic characteristic lengths are incorporated in the field and angular dependence of the critical current density. This is helpful in understanding the physical essence of the scaling behavior in the experiments for critical current anisotropy. We discuss the role of strong and weak point defects in the anisotropic flux-lattice pinning. Relevance of the theory to the critical-state model is dictated as well.

  3. On the density dependent hadron field theory at finite temperature and its thermodynamical consistency

    CERN Document Server

    Avancini, S S; Chiapparini, M; Peres-Menezes, D

    2004-01-01

    In this work we study in a formal way the density dependent hadron field theory at finite temperature for nuclear matter. The thermodynamical potential and related quantities, as energy density and pressure are derived in two different ways. We first obtain the thermodynamical potential from the grand partition function, where the Hamiltonian depends on the density operator and is truncated at first order. We then reobtain the thermodynamical potential by calculating explicitly the energy density in a Thomas-Fermi approximation and considering the entropy of a fermi gas. The distribution functions for particles and antiparticles are the output of the minimization of the thermodynamical potential. It is shown that in the mean field theory the thermodynamical consistency is achieved. The connection with effective chiral lagrangians with Brown-Rho scaling is discussed.

  4. Rocket-borne measurements of electron temperature and density with the Electron Retarding Potential Analyzer instrument

    Science.gov (United States)

    Cohen, I. J.; Widholm, M.; Lessard, M. R.; Riley, P.; Heavisides, J.; Moen, J. I.; Clausen, L. B. N.; Bekkeng, T. A.

    2016-07-01

    Determining electron temperature in the ionosphere is a fundamentally important measurement for space science. Obtaining measurements of electron temperatures at high altitudes (>700 km) is difficult because of limitations on ground-based radar and classic spacecraft instrumentation. In light of these limitations, the rocket-borne Electron Retarding Potential Analyzer (ERPA) was developed to allow for accurate in situ measurement of ionospheric electron temperature with a simple and low-resource instrument. The compact ERPA, a traditional retarding potential analyzer with multiple baffle collimators, allows for a straightforward calculation of electron temperature. Since its first mission in 2004, it has amassed significant flight heritage and obtained data used in multiple studies investigating a myriad of phenomena related to magnetosphere-ionosphere coupling. In addition to highlighting the scientific contributions of the ERPA instrument, this paper outlines its theory and operation, the methodology used to obtain electron temperature measurements, and a comparative study suggesting that the ERPA can also provide electron density measurements.

  5. Modelling the influence of temperature anisotropies on poloidal asymmetries of density in the core of rotating plasmas

    Science.gov (United States)

    Bilato, R.; Maj, O.; Angioni, C.

    2014-07-01

    A consistent set of equations is derived to model poloidal density asymmetries induced by temperature anisotropies in tokamak rotating plasmas. The model can be applied to compute poloidal density asymmetry of highly charged impurities due to additional plasma heating.

  6. The XMM Cluster Survey: evolution of the velocity dispersion-temperature relation over half a Hubble time

    Science.gov (United States)

    Wilson, Susan; Hilton, Matt; Rooney, Philip J.; Caldwell, Caroline; Kay, Scott T.; Collins, Chris A.; McCarthy, Ian G.; Romer, A. Kathy; Bermeo, Alberto; Bernstein, Rebecca; da Costa, Luiz; Gifford, Daniel; Hollowood, Devon; Hoyle, Ben; Jeltema, Tesla; Liddle, Andrew R.; Maia, Marcio A. G.; Mann, Robert G.; Mayers, Julian A.; Mehrtens, Nicola; Miller, Christopher J.; Nichol, Robert C.; Ogando, Ricardo; Sahlén, Martin; Stahl, Benjamin; Stott, John P.; Thomas, Peter A.; Viana, Pedro T. P.; Wilcox, Harry

    2016-11-01

    We measure the evolution of the velocity dispersion-temperature (σv-TX) relation up to z = 1 using a sample of 38 galaxy clusters drawn from the XMM Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high-redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 z > 0.5 clusters observed with the Gemini Multi Object Spectographs instruments on the Gemini telescopes. Using an orthogonal regression method, we find that the slope of the relation is steeper than that expected if clusters were self-similar, and that the evolution of the normalization is slightly negative, but not significantly different from zero (σv ∝ T0.86±0.14E(z)-0.37±0.33). We verify our results by applying our methods to cosmological hydrodynamical simulations. The lack of evolution seen in our data is consistent with simulations that include both feedback and radiative cooling.

  7. A compact single-camera system for high-speed, simultaneous 3-D velocity and temperature measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Louise; Sick, Volker; Frank, Jonathan H.

    2013-09-01

    The University of Michigan and Sandia National Laboratories collaborated on the initial development of a compact single-camera approach for simultaneously measuring 3-D gasphase velocity and temperature fields at high frame rates. A compact diagnostic tool is desired to enable investigations of flows with limited optical access, such as near-wall flows in an internal combustion engine. These in-cylinder flows play a crucial role in improving engine performance. Thermographic phosphors were proposed as flow and temperature tracers to extend the capabilities of a novel, compact 3D velocimetry diagnostic to include high-speed thermometry. Ratiometric measurements were performed using two spectral bands of laser-induced phosphorescence emission from BaMg2Al10O17:Eu (BAM) phosphors in a heated air flow to determine the optimal optical configuration for accurate temperature measurements. The originally planned multi-year research project ended prematurely after the first year due to the Sandia-sponsored student leaving the research group at the University of Michigan.

  8. Low temperature London penetration depth and superfluid density in Fe-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunsoo [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    The superconducting gap symmetry of the Fe-based superconductors was studied by measurements and analysis of London penetration depth and super uid density. Tunnel diode resonator technique for these measurements was implemented in a dilution refrigerator allowing for the temperatures down to 50 mK. For the analysis of the super uid density, we used both experimental studies of Al-coated samples and original thermodynamic approach based on Rutgers relation. In three systems studied, we found that the superconducting gap at the optimal doping is best described in multi-gap full gap scenario. By performing experiments on samples with arti cially introduced disorder with heavy ion irradiation, we show that evolution of the superconducting transition temperature and of the super uid density are consistent with full-gap sign changing s superconducting state. The superconducting gap develops strong modulation both in the under-doped and the over-doped regimes. In the terminal hole-doped KFe{sub 2}As{sub 2}, both temperature dependence of the super uid density and its evolution with increase of the scattering rate are consistent with symmetry imposed vertical line nodes in the superconducting gap. By comparative studies of hole-doped (Ba,K)Fe{sub 2}As{sub 2} and electron-doped Ca10-3-8, we show that the superconducting gap modulation in the under-doped regime is intrinsic and is not induced by the coexisting static magnetic order.

  9. On the time and temperature dependent behaviour of laminated amorphous polymers subjected to low-velocity impact

    CERN Document Server

    Rühl, Andreas

    2017-01-01

    The thesis investigates a polymeric laminate consisting of poly(methyl methacrylate) (PMMA) and thermoplastic polyurethane (TPU) experimentally and numerically with regard to its impact behaviour and applicability. After a basic characterization of the monolithic materials, PMMA-TPU-PMMA laminates were subjected to impact loadings at velocities up to 5 m/s using threepoint bending and dart impact tests. Based on the experimental basis, different material models for the Finite Element simulation are presented, which are able to capture the time and temperature dependent behaviour of the laminate. Final validation experiments, consisting of head-dummy impacts at 10 m/s on automotive side windows, were conducted for PMMA and the laminate in order to investigate their applicability as glass substitution products. The Content Introduction · Fundamentals · Experimental Investigation · Material Modelling of PMMA · Material Modelling of TPU · Simulation of PMMA-TPU Laminate · Component Tests and Validation · S...

  10. Temperature and relative density of atomic hydrogen in a multicusp H sup minus volume source

    Energy Technology Data Exchange (ETDEWEB)

    Bruneteau, A.M.; Hollos, G.; Bacal, M. (Laboratoire de Physique des Milieux Ionises, Laboratoire du Centre National de la Recherche Scientifique, Ecole Polytechnique, 91128 Palaiseau Cedex, (France)); Bretagne, J. (Laboratoire de Physique des Gaz et des Plasmas, LA73 du Centre National de la Recherche Scientifique, Universite de Paris-Sud, 91405 Orsay (France))

    1990-06-15

    The Balmer {beta} and {gamma} line shapes have been analyzed to determine the relative density and the temperature of hydrogen atoms in magnetic multicusp plasma generators. Results for a 90-V, 4--40-mTorr, 1--18-A conventional multicusp plasma generator and a 50-V, 4-mTorr, 1--15-A hybrid multicusp plasma generator are presented. The relative number density of hydrogen atoms increased smoothly with pressure and discharge current but never exceeded 10%. The absolute atomic number density in a 90-V 10-A discharge varied in proportion with pressure. The atomic temperature (in the 0.1--0.4-eV range) decreased with pressure and slowly increased with the discharge current. The role of atoms in the processes determining the H{sup {minus}} temperature and the H{sub 2} vibrational and rotational temperatures is discussed. The results confirm that in multicusp negative-ion sources collisional excitation of ground state atoms and molecules by energetic electrons is the dominant process in Balmer-{beta} and -{gamma} light emission.

  11. Atomic temperature and density in multicusp H sup minus volume sources

    Energy Technology Data Exchange (ETDEWEB)

    Bruneteau, A.M.; Hollos, G.; Leroy, R.; Berlemont, P.; Bacal, M. (Laboratoire du C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Bertagne, J. (Laboratoire de Physique des Gaz et des Plasmas, LA73 du CNRS, Universite de Paris-Sud, 91405 Orsay (France))

    1990-08-05

    The Balmer {beta} and {gamma} line shapes have been analyzed to determine the relative density and the temperature of hydrogen atoms in magnetic multicusp plasma generators. Results for a 90 V, 4--40 mTorr, 1--18 A conventional multicusp plasma generator and a 50 V, 4 mTorr, 1--15 A hybrid multicusp plasma generator are presented. The relative number density of hydrogen atoms increases smoothly with pressure and discharge current but never exceeds 10%. The absolute atomic number density in a 90 V--10 A discharge varies in proportion with pressure. The atomic temperature (in the 0.1--0.4 eV range) decreases with pressure and slowly increases with the discharge current. The role of atoms in the processes determining the H{sup {minus}} temperature and the H{sub 2} vibrational and rotational temperatures is discussed. The results confirm that in multicusp negative ion sources collisional excitation of ground-state atoms and molecules by energetic electrons is the dominant process in Balmer {beta} and {gamma} light emission.

  12. Neutrino Dispersion Relations at Finite Temperature and Density in the Left-Right Symmetric Model

    CERN Document Server

    Villalba-Pardo, F D

    2010-01-01

    In the framework of the Left-Right Symmetric Model, where left-handed neutrinos are massive via the see-saw mechanism, we determine the effects of temperature and density in the dispersion relations for neutrinos, considering that there exists an excess of leptons over antileptons in the plasma. To achieve this we first calculate the dispersion relations at finite temperature and density, computing the neutrino self-energy at one loop order in perturbation theory, obtaining a fully analytic expression for this self-energy even in the fully broken symmetry case by using the Mellin summation technique. From the dispersion relation found from the self energy we obtain the thermal effective mass for neutrinos at high temperature limit. This result allow us to establish the effect of finite temperature and density for neutrino oscillations in thermal and dense media for this framework. We can do it if we take into account that the oscillation patterns depend explicitly on neutrino masses. As a result, a generaliza...

  13. [Effect of water temperature, stocking density and feeding cycle on growth of juvenile Poecilobdella manillensis].

    Science.gov (United States)

    Cheng, Bo-xing; Liu, Fei; Guo, Qiao-sheng; Shi, Hong-zhuan; Li, Meng-meng; Lu, Yu-xi

    2015-03-01

    The effect of water temperature, stocking density and feeding cycle on the growth of Poecilobdella manillensis juvenile was conducted P. manillensis was conducted respectively under different conditions: water temperatures(18, 22, 26, 30,34, 38 degrees C and CT), stocking density (75, 125, 200, 275, 350 individual/L) and feeding cycle(2, 4, 6, 8, 12, 16 d). After 30 days, survival rate, weight gain rate, specific growth rate were measured. There was a significant correlation between water temperature and specific growth rate (γ = -0.066x2 + 3.543 1x -38.09, R2 = 0.837 9). Based on the regression equation, the specific growth rate of P. manillensis achieved the maximum (9.461 4) at 26.84 degrees C. And the most optimal water temperature was 26-30 degrees C. Meanwhile, the survival rates of P. manillensis was 0 at 38 degrees C in 3 d. There was significant negative correlation between density and specific growth rate (γ = -0.005 7x + 9.197 3, R2 = 0.998 3) and between feeding cycle and specific growth rate (γ = -0.468 2x + 10.574, R2 = 0.998 8).

  14. Speckle measurements of density and temperature profiles in a model gas circuit breaker

    Science.gov (United States)

    Stoller, P. C.; Panousis, E.; Carstensen, J.; Doiron, C. B.; Färber, R.

    2015-01-01

    Speckle imaging was used to measure the density and temperature distribution in the arc zone of a model high voltage circuit breaker during the high current phase and under conditions simulating those present during current-zero crossings (current-zero-like arc); the arc was stabilized by a transonic, axial flow of synthetic air. A single probe beam was used; thus, accurate reconstruction was only possible for axially symmetric gas flows and arc channels. The displacement of speckles with respect to a reference image was converted to a line-of-sight integrated deflection angle, which was in turn converted into an axially symmetric refractive index distribution using a multistep process that made use of the inverse Radon transform. The Gladstone-Dale relation, which gives the index of refraction as a function of density, was extended to high temperatures by taking into account dissociation and ionization processes. The temperature and density were determined uniquely by assuming that the pressure distribution in the case of cold gas flow (in the absence of an arc) is not modified significantly by the arc. The electric conductivity distribution was calculated from the temperature profile and compared to measurements of the arc voltage and to previous results published in the literature for similar experimental conditions.

  15. Predicting the glass transition temperature as function of crosslink density and polymer interactions in rubber compounds

    Science.gov (United States)

    D'Escamard, Gabriella; De Rosa, Claudio; Auriemma, Finizia

    2016-05-01

    Crosslink sulfur density in rubber compounds and interactions in polymer blends are two of the composition elements that affect the rubber compound properties and glass transition temperature (Tg), which is a marker of polymer properties related to its applications. Natural rubber (NR), butadiene rubber (BR) and styrene-butadiene rubber (SBR) compounds were investigated using calorimetry (DSC) and dynamic mechanical analysis (DMA). The results indicate that the Di Marzio's and Schneider's Models predict with accuracy the dependence of Tg on crosslink density and composition in miscible blends, respectively, and that the two model may represent the base to study the relevant "in service" properties of real rubber compounds.

  16. Radial oscillations of magnetized proto strange stars in temperature- and density-dependent quark mass model

    Indian Academy of Sciences (India)

    V K Gupta; Asha Gupta; S Singh; J D Anand

    2003-10-01

    We report on the study of the mass–radius (–) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modification, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We find that the effect of magnetic field, both on the maximum mass and radial frequencies, is rather small. Also a proto strange star, whether magnetized or otherwise, is more likely to evolve into a strange star rather than transform into a black hole.

  17. Numerical study of QCD phase diagram at high temperature and density by a histogram method

    CERN Document Server

    Ejiri, Shinji; Hatsuda, Tetsuo; Kanaya, Kazuyuki; Nakagawa, Yoshiyuki; Ohno, Hiroshi; Saito, Hana; Umeda, Takashi

    2012-01-01

    We study the QCD phase structure at high temperature and density adopting a histogram method. Because the quark determinant is complex at finite density, the Monte-Carlo method cannot be applied directly. We use a reweighting method and try to solve the problems which arise in the reweighting method, i.e. the sign problem and the overlap problem. We discuss the chemical potential dependence of the probability distribution function in the heavy quark mass region and examine the applicability of the approach in the light quark region.

  18. Estimation of femoral bone density from trabecular direct wave and cortical guided wave ultrasound velocities measured at the proximal femur in vivo

    DEFF Research Database (Denmark)

    Barkmann, Reinhard; Dencks, Stefanie; Bremer, Alexander

    2008-01-01

    Bone mineral density (BMD) of the proximal femur is a predictor of hip fracture risk. We developed a Quantitative Ultrasound (QUS) scanner for measurements at this site with similar performance (FemUS). In this study we tested if ultrasound velocities of direct waves through trabecular bone...... echoes reflected from the skin of the leg to yield speed-of-sound (SOS) of different wave components. Data were cross-calibrated and pooled (62 women). Bivariate correlations and a multivariate model were calculated for the estimation of femur BMD. BMD correlated both with trabecular and cortical SOS...

  19. Time-resolved electron density and electron temperature measurements in nanosecond pulse discharges in helium

    Science.gov (United States)

    Roettgen, A.; Shkurenkov, I.; Simeni Simeni, M.; Petrishchev, V.; Adamovich, I. V.; Lempert, W. R.

    2016-10-01

    Thomson scattering is used to study temporal evolution of electron density and electron temperature in nanosecond pulse discharges in helium sustained in two different configurations, (i) diffuse filament discharge between two spherical electrodes, and (ii) surface discharge over plane quartz surface. In the diffuse filament discharge, the experimental results are compared with the predictions of a 2D plasma fluid model. Electron densities are put on an absolute scale using pure rotational Raman spectra in nitrogen, taken without the plasma, for calibration. In the diffuse filament discharge, electron density and electron temperature increase rapidly after breakdown, peaking at n e  ≈  3.5 · 1015 cm-3 and T e  ≈  4.0 eV. After the primary discharge pulse, both electron density and electron temperature decrease (to n e ~ 1014 cm-3 over ~1 µs and to T e ~ 0.5 eV over ~200 ns), with a brief transient rise produced by the secondary discharge pulse. At the present conditions, the dominant recombination mechanism is dissociative recombination of electrons with molecular ions, \\text{He}2+ . In the afterglow, the electron temperature does not relax to gas temperature, due to superelastic collisions. Electron energy distribution functions (EEDFs) inferred from the Thomson scattering spectra are nearly Maxwellian, which is expected at high ionization fractions, when the shape of EEDF is controlled primarily by electron-electron collisions. The kinetic model predictions agree well with the temporal trends detected in the experiment, although peak electron temperature and electron density are overpredicted. Heavy species temperature predicted during the discharge and the early afterglow remains low and does not exceed T  =  400 K, due to relatively slow quenching of metastable He* atoms in two-body and three-body processes. In the surface discharge, peak electron density and electron temperature are n e  ≈  3 · 1014 cm3 and T e

  20. Effects of temperature and ionization density in medical luminescence dosimetry using Al2O3:C

    DEFF Research Database (Denmark)

    Edmund, Jens Morgenthaler

    2007-01-01

    A new system containing small crystals of aluminum oxide doped with carbon (Al2O3:C) attached to optical fiber cables has recently been introduced. During irradiation, the system monitors the radioluminescence (RL) from the crystals and after irradiation, an optically stimulated luminescence (OSL......) signal can be read out by stimulating the crystal with light. This thesis applies the initial part and the total area of the resulting OSL decay curve for dosimetry measurements and investigates the effects of temperature and proton energy, i.e. ionization density, on the RL and OSL signals from Al2O3:C...... temperature is kept constant, one can find an integration time which provides an OSL signal independent of stimulation temperature. Overall, the RL and OSL signals vary between -0.2 to 0.6% per C. Thermal effects were simulated with a band structure model and indicated that the temperature effects are caused...

  1. Constant-temperature level densities in the quasi-continuum of Th and U isotopes

    CERN Document Server

    Guttormsen, M; Wilson, J N; Aiche, M; Bernstein, L A; Ducasse, Q; Giacoppo, F; Goergen, A; Gunsing, F; Hagen, T W; Larsen, A C; Lebois, M; Leniau, B; Renstroem, T; Rose, S J; Siem, S; Tornyi, T; Tveten, G M; Wiedeking, M

    2013-01-01

    Particle-gamma coincidences have been measured to obtain gamma-ray spectra as a function of excitation energy for 231-233Th and 237-239U. The level densities, which were extracted using the Oslo method, show a constant temperature behavior. The isotopes display very similar temperatures in the quasi-continuum, however, the even-odd isotopes reveal a constant entropy increase Delta S compared to their even-even neighbors. The entropy excess depends on available orbitals for the last unpaired valence neutron of the heated nuclear system. Also, experimental microcanonical temperature and heat capacity have been extracted. Several poles in the heat capacity curve support the idea that an almost continuous melting of Cooper pairs is responsible for the constant-temperature behavior.

  2. Space density distribution of galaxies in the absolute magnitude - rotation velocity plane: a volume-complete Tully-Fisher relation from CALIFA stellar kinematics

    Science.gov (United States)

    Bekeraité, S.; Walcher, C. J.; Falcón-Barroso, J.; Garcia Lorenzo, B.; Lyubenova, M.; Sánchez, S. F.; Spekkens, K.; van de Ven, G.; Wisotzki, L.; Ziegler, B.; Aguerri, J. A. L.; Barrera-Ballesteros, J.; Bland-Hawthorn, J.; Catalán-Torrecilla, C.; García-Benito, R.

    2016-10-01

    We measured the distribution in absolute magnitude - circular velocity space for a well-defined sample of 199 rotating galaxies of the Calar Alto Legacy Integral Field Area Survey (CALIFA) using their stellar kinematics. Our aim in this analysis is to avoid subjective selection criteria and to take volume and large-scale structure factors into account. Using stellar velocity fields instead of gas emission line kinematics allows including rapidly rotating early-type galaxies. Our initial sample contains 277 galaxies with available stellar velocity fields and growth curve r-band photometry. After rejecting 51 velocity fields that could not be modelled because of the low number of bins, foreground contamination, or significant interaction, we performed Markov chain Monte Carlo modelling of the velocity fields, from which we obtained the rotation curve and kinematic parameters and their realistic uncertainties. We performed an extinction correction and calculated the circular velocity vcirc accounting for the pressure support of a given galaxy. The resulting galaxy distribution on the Mr-vcirc plane was then modelled as a mixture of two distinct populations, allowing robust and reproducible rejection of outliers, a significant fraction of which are slow rotators. The selection effects are understood well enough that we were able to correct for the incompleteness of the sample. The 199 galaxies were weighted by volume and large-scale structure factors, which enabled us to fit a volume-corrected Tully-Fisher relation (TFR). More importantly, we also provide the volume-corrected distribution of galaxies in the Mr-vcirc plane, which can be compared with cosmological simulations. The joint distribution of the luminosity and circular velocity space densities, representative over the range of -20 > Mr > -22 mag, can place more stringent constraints on the galaxy formation and evolution scenarios than linear TFR fit parameters or the luminosity function alone. Galaxies main

  3. The QCD equation of state at high temperature and small density from the lattice

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Chuan

    2008-03-15

    In this thesis we have analyzed bulk thermodynamic properties of QCD at high temperature and small but non-vanishing baryon density on lattices. We have used the integration method to calculate the pressure at zero chemical potentials. The thermodynamic quantities are normalized such that they vanish at zero temperature. The zero temperature calculations are thus needed for both calibrating the lattices and the subtraction procedure for the normalizations. In this study, we have scanned a wide range of temperature and constructed a line of constant physics, on which the strange pseudo-scalar meson mass and kaon mass are kept at their physical values and the light pseudo-scalar meson mass is about 220 MeV. Our calculations are mostly carried out on lattices with cut-offs a=1/4 T and 1/6 T, where T is the system temperature. All thermodynamic quantities, such as pressure, energy density as well as energy-momentum trace anomaly, show small cut-off effects. We have also calculated the trace anomaly at high temperatures on N=8 lattices to check that the lattice cut-off effects are under control. In order to study the QCD thermodynamics at small chemical potentials, we have used the Taylor expansion method. The pressure is expanded in terms of quark chemical potentials and the expansion coefficients at zero chemical potentials are calculated up to the fourth order on both N=4 and 6 lattices. Using these coefficients thermodynamic quantities, e.g. pressure and number densities, have been constructed and shown. (orig.)

  4. Constraining snowmelt in a temperature-index model using simulated snow densities

    Science.gov (United States)

    Bormann, Kathryn J.; Evans, Jason P.; McCabe, Matthew F.

    2014-09-01

    Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027 g cm-3 to -0.004 g cm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136 mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

  5. Constraining snowmelt in a temperature-index model using simulated snow densities

    KAUST Repository

    Bormann, Kathryn J.

    2014-09-01

    Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027gcm-3 to -0.004gcm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

  6. NIHAO project II: halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

    Science.gov (United States)

    Butsky, Iryna; Macciò, Andrea V.; Dutton, Aaron A.; Wang, Liang; Obreja, Aura; Stinson, Greg S.; Penzo, Camilla; Kang, Xi; Keller, Ben W.; Wadsley, James

    2016-10-01

    We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects) cosmological simulations to study the effects of galaxy formation on key properties of dark matter (DM) haloes. NIHAO consists of ≈90 high-resolution smoothed particle hydrodynamics simulations that include (metal-line) cooling, star formation, and feedback from massive stars and supernovae, and cover a wide stellar and halo mass range: 106 ≲ M*/M⊙ ≲ 1011(109.5 ≲ Mhalo/M⊙ ≲ 1012.5). When compared to DM-only simulations, the NIHAO haloes have similar shapes at the virial radius, Rvir, but are substantially rounder inside ≈0.1Rvir. In NIHAO simulations, c/a increases with halo mass and integrated star formation efficiency, reaching ˜0.8 at the Milky Way mass (compared to 0.5 in DM-only), providing a plausible solution to the long-standing conflict between observations and DM-only simulations. The radial profile of the phase-space Q parameter (ρ/σ3) is best fit with a single power law in DM-only simulations, but shows a flattening within ≈0.1Rvir for NIHAO for total masses M > 1011 M⊙. Finally, the global velocity distribution of DM is similar in both DM-only and NIHAO simulations, but in the solar neighbourhood, NIHAO galaxies deviate substantially from Maxwellian. The distribution is more symmetric, roughly Gaussian, with a peak that shifts to higher velocities for Milky Way mass haloes. We provide the distribution parameters which can be used for predictions for direct DM detection experiments. Our results underline the ability of the galaxy formation processes to modify the properties of DM haloes.

  7. Temperature and composition-dependent density of states in organic small-molecule/polymer blend transistors

    Science.gov (United States)

    Hunter, Simon; Mottram, Alexander D.; Anthopoulos, Thomas D.

    2016-07-01

    The density of trap states (DOS) in organic p-type transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES ADT), the polymer poly(triarylamine) and blends thereof are investigated. The DOS in these devices are measured as a function of semiconductor composition and operating temperature. We show that increasing operating temperature causes a broadening of the DOS below 250 K. Characteristic trap depths of ˜15 meV are measured at 100 K, increasing to between 20 and 50 meV at room-temperature, dependent on the semiconductor composition. Semiconductor films with high concentrations of diF-TES ADT exhibit both a greater density of trap states as well as broader DOS distributions when measured at room-temperature. These results shed light on the underlying charge transport mechanisms in organic blend semiconductors and the apparent freezing-out of hole conduction through the polymer and mixed polymer/small molecule phases at temperatures below 225 K.

  8. Superfluid density and superconducting transition temperature in Bi-based cuprate single crystals.

    Science.gov (United States)

    Gasparov, L.; Tanner, D.; Berger, H.; Forro, L.; Margaritondo, G.

    2000-03-01

    We present temperature-dependent reflectance measurements for Bi-based cuprate single crystals in the frequency range from 100 to 40,000 cm-1 (0.012--5 eV). The optical conductivity is obtained by Kramers-Kronig analysis. We compare differently doped Bi-2212 (particularly in the underdoped regime) as well as Pr-doped Bi-2212 crystals by analyzing optical conductivity in the framework of a two-fluid approach. This approach allows us to study correlations between superfluid density and superconducting transition temperature of these materials.

  9. Phase Structure in a Quark Mass Density-and-Temperature-Dependent Model

    Institute of Scientific and Technical Information of China (English)

    WEN Xin-Jian; PENG Guang-Xiong; SHEN Peng-Nian

    2007-01-01

    The phase diagram of bulk quark matter in equilibrium with a finite hadronic gas is studied. Different from previous investigations, we treat the quark phase with the quark rnass density-and-temperature-dependent model to take the strong quark interaction into account, while the hadron phase is treated by hard core repulsion factor. It is found that the phase diagram in this model is, in several aspects, different from those in the conventional MIT bag model, especially at high temperature. The new phase diagram also has strong effects on the mass-radius relation of compact hybrid stars.

  10. Temperature-dependence of Threshold Current Density-Length Product in Metallization Lines: A Revisit

    Science.gov (United States)

    Saptono Duryat, Rahmat; Kim, Choong-Un

    2016-04-01

    One of the important phenomena in Electromigration (EM) is Blech Effect. The existence of Threshold Current Density-Length Product or EM Threshold has such fundamental and technological consequences in the design, manufacture, and testing of electronics. Temperature-dependence of Blech Product had been thermodynamically established and the real behavior of such interconnect materials have been extensively studied. The present paper reviewed the temperature-dependence of EM threshold in metallization lines of different materials and structure as found in relevant published articles. It is expected that the reader can see a big picture from the compiled data, which might be overlooked when it was examined in pieces.

  11. Two-dimensional simulations of temperature and current-density distribution in electromigrated structures

    Science.gov (United States)

    Kießig, Birgit; Schäfer, Roland; von Löhneysen, Hilbert

    2014-01-01

    We report on the application of a feedback-controlled electromigration technique for the formation of nanometre-sized gaps in mesoscopic gold wires and rings. The effect of current density and temperature, linked via Joule heating, on the resulting gap size is investigated. Our experiments include in situ measurements of the evolution of the electrical resistance and of the structure of the device during electromigration. Experimentally, a good thermal coupling to the substrate turned out to be crucial to reach electrode spacings below 10 nm and to avoid overall melting of the nanostructures. This finding is supported by numerical calculations of the current-density and temperature profiles for structure layouts subjected to electromigration. The numerical method can be used for optimizing the layout so as to predetermine the location where electromigration leads to the formation of a gap.

  12. Study of Proto Strange Stars (PSS) in Temperature and Density Dependent Quark Mass Model

    CERN Document Server

    Gupta, V K; Singh, S; Anand, J D; Gupta, Asha

    2003-01-01

    We report on the study of the mass-radius (M-R) relation and the radial oscillations of proto strange stars. For the quark matter we have employed the well known density dependent quark mass model and its very recent modification, the temperature and density dependent quark mass model. We find that the maximum mass the star can support increases significantly with the temperature of the star in this model which implies that transition to a black hole at the early stage of formation of the star is inhibited. As for the neutrinos, we find, contrary to the expectation that the M-R and oscillation frequencies are almost independent of the neutrino chemical potentials.

  13. Temperature Buffer Test. Measurements of water content and density of the excavated buffer material

    Energy Technology Data Exchange (ETDEWEB)

    Johannesson, Lars-Erik [Clay Technology AB, Lund (Sweden)

    2010-12-15

    TBT (Temperature Buffer Test) is a joint project between SKB/ANDRA and supported by ENRESA (modeling) and DBE (instrumentation), which aims at understanding and modeling the thermo-hydromechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test was carried out at the - 420 m level in Aespoe HRL in a 8 meters deep and 1.76 m diameter deposition hole, with two heaters (3 m long, 0.6 m diameter), surrounded by a MX-80 bentonite buffer and a confining plug on top anchored with 9 rods. It was installed during spring 2003. The bentonite around upper heater was removed during the period October - December 2009 and the buffer around the lower heater was removed during January - Mars 2010. During dismantling of the buffer, samples were taken on which analyses were made. This report describes the work with the deteroemoeination of the water content and the density of the taken samples. Most of the samples were taken from the buffer by core drilling from the upper surface of each installed bentonite block. The cores had a diameter of about 50 mm and a maximum length equal to the original height of the bentonite blocks (about 500 mm). The water content of the buffer was determined by drying a sample at a temperature of 105 deg C for 24 h and the bulk density was determined by weighing a sample both in the air and immerged in paraffin oil with known density. The water content, dry density, degree of saturation and void ratio of the buffer were then plotted. The plots show that all parts of the buffer had taken up water and the degree of saturation of the buffer varied between 90 - 100%. Large variation in the dry density of the buffer was also observed.

  14. Direct Selective Laser Sintering/Melting of High Density Alumina Powder Layers at Elevated Temperatures

    Science.gov (United States)

    Deckers, J.; Meyers, S.; Kruth, J. P.; Vleugels, J.

    Direct selective laser sintering (SLS) or selective laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800̊C). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μm were successfully produced.

  15. Temporal evolution of electron density and temperature in capillary discharge plasmas

    Science.gov (United States)

    Oh, Seong Y.; Uhm, Han S.; Kang, Hoonsoo; Lee, In W.; Suk, Hyyong

    2010-05-01

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 1018 cm-3 within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3×1018 cm-3 occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  16. Critical point search from an extended parameter space of lattice QCD at finite temperature and density

    CERN Document Server

    Ejiri, Shinji; Yamada, Norikazu

    2016-01-01

    Aiming to understand the phase structure of lattice QCD at nonzero temperature and density, we study the phase transitions of QCD in an extended parameter space, where the number of flavor and quark masses are considered as parameters. Performing simulations of 2 flavor QCD and using the reweighting method, we investigate (2+Nf) flavor QCD at finite density, where two light flavors and Nf massive flavors exist. Calculating probability distribution functions, we determine the critical surface terminating first order phase transitions in the parameter space of the light quark mass, the heavy quark mass and the chemical potential. Through the study of the many flavor system, we discuss the phase structure of QCD at finite density.

  17. Evaluation of temperature and seismic gradients of Central Turkmeniya from data from velocities of longitudinal waves with high P and T

    Energy Technology Data Exchange (ETDEWEB)

    Volarovich, M.P.; Lyubimova, Ye.A.; Volynets, L.N.

    1981-01-01

    Processing of data from deep seismic probing by the ''method tau (P)'' results in the obtaining of an area of all possible velocity sections in which one should search for specific solutions of the inverse seismic task. The conducted analysis of velocity gradients makes it possible to make a more purposeful search for individual velocity models according to the lithological-petrological model of the layers of the earth's crust and upper mantle. Thus, joint use of results of experimental study of the velocities of longitudinal waves in rock samples and high pressures and temperatures and thermal data makes it possible to reduce the ambiguity of the seismic task and to reduce the number of possible lithological-petrological models in constructing a velocity model of the earth's crust and upper mantle using seismic observations.

  18. CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

    NARCIS (Netherlands)

    Westerhout, J.; Cardozo, N. J. L.; Rapp, J.; van Rooij, G. J.

    2009-01-01

    The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature T-e=0.1-2.5 eV and electron density n(e)=(0.5-5) X 10(20) m(-3)] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to >10(6

  19. Temperature and field dependence of the mobility in 1D for a Gaussian density of states

    Science.gov (United States)

    Pasveer, W. F.; Bobbert, P. A.; Michels, M. A. J.

    2004-01-01

    The temperature and field-dependent mobility of a charge carrier in a gaussian density of states has been analyzed, based on a numerically exact solution of the Master equation. In this way we get a microscopic insight into the origin of the mobility and find some new features pointing to relevance of the Fermi level and of variable-range hopping to sites further away than nearest ones.

  20. DENSITY, EQUILIBRIUM HEAT OF FUSION AND EQUILIBRIUM MELTING TEMPERATURE OF NYLON 1010

    Institute of Scientific and Technical Information of China (English)

    FENG Jinhua; MO Zishen; CHEN Donglin

    1990-01-01

    The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweather 's method crystalline density ρc and amorphous density ρa were estimated to be 1.098 and 1.003 g/cm3 respectively by extrapolating the straight lines of the IR absorbance against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρc was too low in value.Thereby the value of the ratio ρc / ρa is far less than generally accepted mean value for most crystalline polymers. Accordingly, traditional X-raydiffraction method was used through determining the crystalline dimension(a=4.9(A), b=5.4(A) , c=27.8(A) , α=4 9 °β=77.0 °γ= 63.5 ° ) , and a rather correct value of ρc or the crystal density 1. 13 g/cm3 was obtained . The equilibrium heat of fusion Δ H 0m was estimated to be 244.0 J/g plotting Δ Hm's of specimens with different crystallinity against their corresponding specific volumes Vsp and extrapolating to completely crystalline condition ( Vcsp = 1 /ρc) As to the equilibrium melting temperature T0m ,because of the easiness ofrecrystallization of melt crystallized Nylon 1010 specimen ,the well-known Hoffman's Tm-Tc method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T0m 487 seems to be fairly reasonable.

  1. Temperature dependence of the optical properties of high-density GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Ryan P.; Kim, Jongsu [Yeungnam University, Gyeongsan (Korea, Republic of); Lee, Sangjun; Noh, Samkyu [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Kim, Jinsoo [Chonbuk National University, Jeonju (Korea, Republic of); Leem, Jaeyoung [Inje University, Gimhae (Korea, Republic of); Song, Jindong [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2012-05-15

    We investigate the effect of the quantum dot (QD) density on the thermal escape and the retrapping processes of carriers for unstrained GaAs/AlGaAs QDs through temperature-dependent photoluminescence measurements. We fabricated high-density GaAs QDs (8.4 x 10{sup 10}/cm{sup 2}, dot-dot distance ∼34 nm) on an Al{sub 0.3}Ga{sub 0.7}As/GaAs (111)A surface by using droplet epitaxy. The average lateral size and height of the GaAs QDs are 24 and 6 nm, respectively. Temperature-dependent photoluminescence (PL) studies show that high-density GaAs QDs undergo a sigmoidal-shape energy shift. The sigmoidal dependence of the PL peak energy can be explained by thermal escaping of carriers followed by re-trapping by QDs. Our analysis indicates that the re-trapping probability of thermally-escaped carriers increases with decreasing dot-to-dot distance (corresponding to an increase in the QD density).

  2. TEMPERATURE AND ELECTRON DENSITY DIAGNOSTICS OF A CANDLE-FLAME-SHAPED FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Guidoni, S. E. [NASA Goddard Space Flight Center/CUA, Code 674, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); McKenzie, D. E.; Longcope, D. W.; Yoshimura, K. [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Plowman, J. E., E-mail: silvina.e.guidoni@nasa.gov [High Altitude Observatory, National Center for Atmospheric Research P.O. Box 3000, Boulder, CO 80307-3000 (United States)

    2015-02-10

    Candle-flame-shaped flares are archetypical structures that provide indirect evidence of magnetic reconnection. A flare resembling Tsuneta's famous 1992 candle-flame flare occurred on 2011 January 28; we present its temperature and electron density diagnostics. This flare was observed with Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Hinode/X-Ray Telescope (XRT), and Solar Terrestrial Relations Observatory Ahead (STEREO-A)/Extreme Ultraviolet Imager, resulting in high-resolution, broad temperature coverage, and stereoscopic views of this iconic structure. The high-temperature images reveal a brightening that grows in size to form a tower-like structure at the top of the posteruption flare arcade, a feature that has been observed in other long-duration events. Despite the extensive work on the standard reconnection scenario, there is no complete agreement among models regarding the nature of this high-intensity elongated structure. Electron density maps reveal that reconnected loops that are successively connected at their tops to the tower develop a density asymmetry of about a factor of two between the two legs, giving the appearance of ''half-loops''. We calculate average temperatures with a new fast differential emission measure (DEM) method that uses SDO/AIA data and analyze the heating and cooling of salient features of the flare. Using STEREO observations, we show that the tower and the half-loop brightenings are not a line-of-sight projection effect of the type studied by Forbes and Acton. This conclusion opens the door for physics-based explanations of these puzzling, recurrent solar flare features, previously attributed to projection effects. We corroborate the results of our DEM analysis by comparing them with temperature analyses from Hinode/XRT.

  3. CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of the z=0.44 galaxy cluster MACS 1206.2-0847

    CERN Document Server

    Biviano, A; Balestra, I; Mercurio, A; Girardi, M; Nonino, M; Grillo, C; Scodeggio, M; Lemze, D; Kelson, D; Umetsu, K; Postman, M; Zitrin, A; Czoske, O; Ettori, S; Lombardi, M; Maier, C; Medezinski, E; Mei, S; Presotto, V; Tozzi, P; Ziegler, B; Annunziatella, M; Bartelmann, M; Benitez, N; Bradley, L; Brescia, M; Broadhurst, T; Coe, D; Demarco, R; Donahue, M; Ford, H; Gobat, R; Graves, G; Koekemoer, A; Kuchner, U; Melchior, P; Meneghetti, M; Merten, J; Moustakas, L; Munari, E; Regos, E; Sartoris, B; Seitz, S; Zheng, W

    2013-01-01

    We use an unprecedented data-set of about 600 redshifts for cluster members, obtained as part of a VLT/VIMOS large programme, to constrain the mass profile of the z=0.44 cluster MACS J1206.2-0847 over the radial range 0-5 Mpc (0-2.5 virial radii) using the MAMPOSSt and Caustic methods. We then add external constraints from the gravitational lensing analysis of Umetsu et al. (2012). We invert the Jeans equation to obtain the velocity-anisotropy profiles of cluster members. With the mass-density and velocity-anisotropy profiles we then obtain the first determination of a cluster pseudo-phase-space density profile. The kinematics and lensing determinations of the cluster mass profile are in excellent agreement. This is very well fitted by a NFW model with mass M200=(1.4 +- 0.2) 10^15 Msun and concentration c200=6 +- 1, only slightly higher than theoretical expectations. Other mass profile models also provide acceptable fits to our data, of (slightly) lower (Burkert, Hernquist, and Softened Isothermal Sphere) or ...

  4. CO2 fluxes and respiration of branch segments of sycamore (Platanus occidentalis L.) examined at different sap velocities, branch diameters, and temperatures.

    Science.gov (United States)

    McGuire, M A; Cerasoli, S; Teskey, R O

    2007-01-01

    Respiration of stems and branches of trees (R(S)) has typically been estimated by measuring radial CO(2) efflux from woody tissue (E(A)) and rates of efflux are often scaled temporally using a temperature relationship (Q(10)). High concentrations of CO(2) in xylem sap ([CO(2)*]) have been shown to affect E(A), and the transport of CO(2) in the xylem stream has been suggested as a mechanism to explain field observations of temperature-independent fluctuations in E(A). Sap velocity and temperature were manipulated in detached branch segments of sycamore (Platanus occidentalis L.) under controlled conditions to quantify these effects. Within individual branches of similar size, E(A) and [CO(2)*] were greater at low sap velocity, while the amount of respired CO(2) transported in sap (transport flux, F(T)) was greater at high sap velocity. E(A) was linearly correlated with [CO(2)*]. In branches of three diameter classes (1, 2, and 3 cm), volume-based E(A), F(T), and R(S) did not differ, but surface-area based CO(2) fluxes increased with diameter class. Regardless of diameter, E(A) accounted for only 30% of respired CO(2) at high sap velocity, while at low sap velocity, E(A) accounted for 71% of respired CO(2). E(A), F(T), and R(S) measured at 5, 20, and 35 degrees C at the same sap velocity showed a typical exponential response to temperature. However, at the lowest temperature, E(A) accounted for only 18% of the CO(2) released from respiring cells compared with 44% at the highest temperature, perhaps due to the effect of temperature on the solubility of CO(2) in water. These results directly demonstrate the transport of respired CO(2) in the xylem stream and may help to explain inconsistencies in stem and branch respiration measurements made in situ.

  5. Comparison of size, terminal fall velocity, and density of bighead carp, silver carp, and grass carp eggs for use in drift modeling

    Science.gov (United States)

    George, Amy E.; Garcia, Tatiana; Chapman, Duane C.

    2017-01-01

    Invasive Asian carp established in the United States spawn in the turbulent water of rivers, and their eggs and early larvae develop while drifting in the current. The eggs, which are believed to perish if they settle before hatching, are slightly denser than water and are held in suspension by water turbulence. It is possible to use egg drift modeling to assess the capability of a river to support the survival of Asian carp eggs. Detection of spawning and estimation of egg abundance in the drift are typically assessed by ichthyoplankton trawls. Correct sampling design and interpretation of trawl data require knowledge of the vertical distribution of eggs in the drift, which can be accomplished with particle transport models. Data that are required to populate models of egg drift and vertical distribution include physical properties of assessed rivers and information on egg size, density, and terminal fall velocity, but data on these egg characteristics have not been previously available. Physical characteristics of the eggs are presented as a function of postfertilization time. We recorded mean egg diameter and terminal fall velocity for eggs from each Asian carp species during the first 5 h of development and at approximately 12 and 22 h postfertilization. Eggs of all species reached their maximum size before 4 h. Water-hardened eggs of Silver Carp Hypophthalmichthys molitrix and Grass Carp Ctenopharyngodon idella were similarly sized in our trials, and water-hardened eggs of Bighead Carp H. nobilis were the largest. After water hardening, Silver Carp eggs sank slowest, and Bighead Carp eggs sank fastest. For a given species, smaller-diameter eggs generally had faster terminal fall velocities and higher specific gravity than larger eggs. We provide regression models of egg density and diameter for all three species, discuss usage of these data in modeling the drift and dispersion of Asian carp eggs, and discuss implications for egg sampling design.

  6. Exact nonlinear analytic Vlasov-Maxwell tangential equilibria with arbitrary density and temperature profiles

    CERN Document Server

    Mottez, F

    2003-01-01

    The tangential layers are characterized by a bulk plasma velocity and a magnetic field that are perpendicular to the gradient direction. They have been extensively described in the frame of the Magneto-Hydro-Dynamic (MHD) theory. But the MHD theory does not look inside the transition region if the transition has a size of a few ion gyroradii. A series of kinetic tangential equilibria, valid for a collisionless plasma is presented. These equilibria are exact analytical solutions of the Maxwell-Vlasov equations. The particle distribution functions are sums of an infinite number of elementary functions parametrized by a vector potential. Examples of equilibria relevant to space plasmas are shown. A model for the deep and sharp density depletions observed in the auroral zone of the Earth is proposed. Tangential equilibria are also relevant for the study of planetary environments and of remote astrophysical plasmas.

  7. Multi-Sensor Core Logger (MSCL) P-wave velocity, gamma-ray density, and magnetic susceptibility whole-core logs of sediment cores collected in 2009 offshore from Palos Verdes, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release includes Multi-Sensor Core Logger (MSCL) P-wave velocity, gamma-ray density, and magnetic susceptibility whole-core logs of sediment...

  8. Power density analysis and optimization of a regenerated closed variable-temperature heat reservoir Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lingen Chen; Junlin Zheng; Fengrui Sun [Naval Univ. of Engineering, Faculty 306, Wuhan (China); Chih Wu [US Naval Academy, Mechanical Engineering Dept., Annapolis, MD (United States)

    2001-06-07

    In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis and optimisation of an irreversible regenerated closed Brayton cycle coupled to variable-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimisation (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, the pressure drop losses at the heater, cooler and regenerator as well as in the piping, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion, and the advantages and disadvantages of maximum power density design are analysed. The maximum power density optimisation is performed in two stages. The first is to search the optimum heat conductance distribution corresponding to the optimum power density among the hot- and cold-side heat exchangers and the regenerator for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the optimum power density between the working fluid and the high-temperature heat source for a fixed ratio of the thermal capacitance rates of two heat reservoirs. The influences of some design parameters, including the effectiveness of the regenerator, the inlet temperature ratio of the heat reservoirs, the effectiveness of the heat exchangers between the working fluid and the heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the optimum heat conductance

  9. Power density analysis and optimization of a regenerated closed variable-temperature heat reservoir Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lingen Chen; Junlin Zheng; Fengrui Sun [Naval University of Engineering, Wuhan (China). Faculty 306; Chih Wu [US Naval Academy, Annapolis, MD (United States). Mechanical Engineering Dept.

    2001-06-07

    In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis and optimization of an irreversible regenerated closed Brayton cycle coupled to variable-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, the pressure drop losses at the heater, cooler and regenerator as well as in the piping, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion, and the advantages and disadvantages of maximum power density design are analysed. The maximum power density optimization is performed in two stages. The first is to search the optimum beat conductance distribution corresponding to the optimum power density among the hot- and cold-side heat exchangers and the regenerator for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the optimum power density between the working fluid and the high-temperature heat source for a fixed ratio of the thermal capacitance rates of two heat reservoirs. The influences of some design parameters, including the effectiveness of the regenerator, the inlet temperature ratio of the heat reservoirs, the effectiveness of the heat exchangers between the working fluid and the heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the optimum heat conductance distribution, the optimum thermal capacitance rate matching, and the maximum power density are provided by

  10. Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    吴静; 姚列明; 朱建华; 韩晓玉; 李文柱

    2012-01-01

    This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum (CXRS) diagnostics tool built on the HL-2A toknmak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutrM beam injection (NBI) heating. Considering the edge effect of the line of CVI 529.06 nm (n= 8-7), which contains three lines (active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE)), and using three Gaussian fitted curves, we obtain the following experimental results: the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m· s^-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

  11. Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

    Science.gov (United States)

    Wu, Jing; Yao, Lieming; Zhu, Jianhua; Han, Xiaoyu; Li, Wenzhu

    2012-11-01

    This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum (CXRS) diagnostics tool built on the HL-2A tokamak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutral beam injection (NBI) heating. Considering the edge effect of the line of CVI 529.06 nm (n = 8~7), which contains three lines (active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE)), and using three Gaussian fitted curves, we obtain the following experimental results: the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m · s-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

  12. Screening of heavy quarks and hadrons at finite temperature and density

    Energy Technology Data Exchange (ETDEWEB)

    Doering, M.

    2006-09-22

    Heavy quarks and hadrons placed in a strongly interacting thermal and baryon chemical quantum field are screened by the medium. I calculate the free energies of heavy quarks and anti-quarks and hadron correlation functions on a 16{sup 3} x 4 lattice in 2-flavour QCD with a bare quark mass of m/T=0.4. The dependence on the interparticle distance determines the screening masses as a function of temperature and density. The Taylor expansion method is used for the baryon chemical potential. The heavy quark screening masses turn out to be in good agreement with perturbation theory for temperatures T>2T{sub c}. The hadron screening masses are consistent with the free quark propagation in the large temperature regime. (orig.)

  13. Constraining decaying dark energy density models with the CMB temperature-redshift relation

    CERN Document Server

    Jetzer, Philippe

    2012-01-01

    We discuss the thermodynamic and dynamical properties of a variable dark energy model with density scaling as $\\rho_x \\propto (1+z)^{m}$, z being the redshift. These models lead to the creation/disruption of matter and radiation, which affect the cosmic evolution of both matter and radiation components in the Universe. In particular, we have studied the temperature-redshift relation of radiation, which has been constrained using a recent collection of cosmic microwave background (CMB) temperature measurements up to $z \\sim 3$. We find that, within the uncertainties, the model is indistinguishable from a cosmological constant which does not exchange any particles with other components. Future observations, in particular measurements of CMB temperature at large redshift, will allow to give firmer bounds on the effective equation of state parameter $w_{eff}$ for such types of dark energy models.

  14. Ion density and temperature variations at altitude of 500 km during moderate seismic activity

    Science.gov (United States)

    Bardhan, Ananna; Khurana, M. S.; Bahal, B. M.; Aggarwal, Malini; Sharma, D. K.

    2017-02-01

    Ionospheric ions (O+ and H+) and temperature (Ti) as precursory parameters to seismic activity have been analysed from year 1995 till 1998, using SROSS-C2 (average altitude range of ∼500 km) satellite measurements for moderate magnitude earthquakes. The details of seismic events during this period are downloaded from United State Geological Survey (USGS) and National Earthquake Information Centre (NEIC) website. 13 seismic events of moderate magnitude (M = 4-5.5) from 1995 to 1998, using SROSS-C2 satellite measurements have been analysed. During seismic affected period, considerable decrease in the density of heavier ion - O+ and increase in the ion temperature (Ti) is observed during all the selected events. Lighter ion - H+ doesn't show any significant change. Electric field and electromagnetic emissions generated due to seismogenic activity could be the plausible initializing agents responsible for change in ion concentration and temperature values during these events.

  15. Limits on decaying dark energy density models from the CMB temperature-redshift relation

    Science.gov (United States)

    Jetzer, Philippe; Tortora, Crescenzo

    2012-03-01

    We discuss the thermodynamic and dynamical properties of a variable dark energy model with density scaling as ρx propto (1 + z)m, z being the redshift. These models lead to the creation/disruption of matter and radiation, which affect the cosmic evolution of both matter and radiation components in the Universe. In particular, we have studied the temperature-redshift relation of radiation, which has been constrained using a recent collection of cosmic microwave background (CMB) temperature measurements up to z ~ 3. We find that, within the uncertainties, the model is indistinguishable from a cosmological constant which does not exchange any particles with other components. Future observations, in particular measurements of CMB temperature at large redshift, will allow to give firmer bounds on the effective equation of state parameter weff for such types of dark energy models.

  16. Measuring the mobility of single crystalline wires and its dependence on temperature and carrier density

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Cleber A; Berengue, Olivia M; Kamimura, Hanay; Chiquito, Adenilson J [NanO LaB-Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil); Leite, Edson R, E-mail: amorim@df.ufscar.br [Laboratorio Interdisciplinar de EletroquImica e Ceramicas, Departamento de Quimica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil)

    2011-05-25

    Kinetic transport parameters are fundamental for the development of electronic nanodevices. We present new results for the temperature dependence of mobility and carrier density in single crystalline In{sub 2}O{sub 3} samples and the method of extraction of these parameters which can be extended to similar systems. The data were obtained using a conventional Hall geometry and were quantitatively described by the semiconductor transport theory characterizing the electron transport as being controlled by the variable range hopping mechanism. A comprehensive analysis is provided showing the contribution of ionized impurities (low temperatures) and acoustic phonon (high temperatures) scattering mechanisms to the electron mobility. The approach presented here avoids common errors in kinetic parameter extraction from field effect data, serving as a versatile platform for direct investigation of any nanoscale electronic materials.

  17. Real-Time Thermographic-Phosphor-Based Temperature Measurements of Thermal Barrier Coating Surfaces Subjected to a High-Velocity Combustor Burner Environment

    Science.gov (United States)

    Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Cruzen, Scott; Condevaux, J. J.; Senk, J. R.; Paul, A. D.

    2011-01-01

    Surface temperature measurements were conducted on metallic specimens coated with an yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC) with a YAG:Dy phosphor layer that were subjected to an aggressive high-velocity combustor burner environment. Luminescence-based surface temperature measurements of the same TBC system have previously been demonstrated for specimens subjected to static furnace or laser heating. Surface temperatures were determined from the decay time of the luminescence signal of the YAG:Dy phosphor layer that was excited by a pulsed laser source. However, the furnace and laser heating provides a much more benign environment than that which exists in a turbine engine, where there are additional challenges of a highly radiant background and high velocity gases. As the next step in validating the suitability of luminescence-based temperature measurements for turbine engine environments, new testing was performed where heating was provided by a high-velocity combustor burner rig at Williams International. Real-time surface temperature measurements during burner rig heating were obtained from the decay of the luminescence from the YAG:Dy surface layer. The robustness of several temperature probe designs in the sonic velocity, high radiance flame environment was evaluated. In addition, analysis was performed to show whether the luminescence decay could be satisfactorily extracted from the high radiance background.

  18. New equations for density, entropy, heat capacity, and potential temperature of a saline thermal fluid

    Science.gov (United States)

    Sun, Hongbing; Feistel, Rainer; Koch, Manfred; Markoe, Andrew

    2008-10-01

    A set of fitted polynomial equations for calculating the physical variables density, entropy, heat capacity and potential temperature of a thermal saline fluid for a temperature range of 0-374 °C, pressure range of 0.1-100 MPa and absolute salinity range of 0-40 g/kg is established. The freshwater components of the equations are extracted from the recently released tabulated data of freshwater properties of Wagner and Pruß [2002. The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. Journal of Physical and Chemical Reference Data 31, 387-535]. The salt water component of the equation is based on the near-linear relationship between density, salinity and specific heat capacity and is extracted from the data sets of Feistel [2003. A new extended Gibbs thermodynamic potential of seawater. Progress in Oceanography 58, 43-114], Bromley et al. [1970. Heat capacities and enthalpies of sea salt solutions to 200 °C. Journal of Chemical and Engineering Data 15, 246-253] and Grunberg [1970. Properties of sea water concentrates. In: Third International Symposium on Fresh Water from the Sea, vol. 1, pp. 31-39] in a temperature range 0-200 °C, practical salinity range 0-40, and varying pressure and is also calibrated by the data set of Millero et al. [1981. Summary of data treatment for the international high pressure equation of state for seawater. UNESCO Technical Papers in Marine Science 38, 99-192]. The freshwater and salt water components are combined to establish a workable multi-polynomial equation, whose coefficients were computed through standard linear regression analysis. The results obtained in this way for density, entropy and potential temperature are comparable with those of existing models, except that our new equations cover a wider temperature—(0-374 °C) than the traditional (0-40 °C) temperature range. One can apply these newly established equations to the calculation of in-situ or

  19. Effects of density and force discretizations on spurious velocities in lattice Boltzmann equation for two-phase flows

    KAUST Repository

    Xiong, Yuan

    2014-04-28

    Spurious current emerging in the vicinity of phase interfaces is a well-known disadvantage of the lattice Boltzmann equation (LBE) for two-phase flows. Previous analysis shows that this unphysical phenomenon comes from the force imbalance at discrete level inherited in LBE (Guo et al 2011 Phys. Rev. E 83 036707). Based on the analysis of the LBE free of checkerboard effects, in this work we further show that the force imbalance is caused by the different discretization stencils: the implicit one from the streaming process and the explicit one from the discretization of the force term. Particularly, the total contribution includes two parts, one from the difference between the intrinsically discretized density (or ideal gas pressure) gradient and the explicit ones in the force term, and the other from the explicit discretized chemical potential gradients in the intrinsically discretized force term. The former contribution is a special feature of LBE which was not realized previously.

  20. Observing the gas temperature drop in the high-density nucleus of L 1544

    Science.gov (United States)

    Crapsi, A.; Caselli, P.; Walmsley, M. C.; Tafalla, M.

    2007-07-01

    Context: The thermal structure of a starless core is crucial for our understanding of the physics in these objects and hence for our understanding of star formation. Theory predicts a gas temperature drop in the inner 5000 AU of the pre-stellar core L 1544, but there has been no observational proof of this. Aims: We performed VLA observations of the NH{3} (1, 1) and (2, 2) transitions towards L 1544 in order to measure the temperature gradient between the high density core nucleus and the surrounding core envelope. Our VLA observation for the first time provide measurements of gas temperature in a core with a resolution smaller than 1000 AU. We have also obtained high resolution Plateau de Bure observations of the 110 GHz 111-101 para-NH2D line in order to further constrain the physical parameters of the high density nucleus. Methods: We combine our interferometric NH{3} and NH2D observations with available single dish measurements in order to estimate the effects of flux loss from extended components upon our data. We have estimated the temperature gradient using a model of the source to fit our data in the u,v plane. As the NH{3}(1, 1) line is extremely optically thick, this also involved fitting a gradient in the NH{3} abundance. In this way, we also measure the [ NH2D] /[ NH{3}] abundance ratio in the inner nucleus. Results: We find that indeed the temperature decreases toward the core nucleus from 12 K down to 5.5 K resulting in an increase of a factor of 50% in the estimated density of the core from the dust continuum if compared with the estimates done with constant temperature of 8.75 K. Current models of the thermal equilibrium can describe consistently the observed temperature and density in this object, simultaneously fitting our temperature profile and the continuum emission. We also found a remarkably high abundance of deuterated ammonia with respect to the ammonia abundance (50% ± 20%), which proves the persistence of nitrogen bearing molecules at

  1. New method in computer simulations of electron and ion densities and temperatures in the plasmasphere and low-latitude ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available A new theoretical model of the Earth’s low- and mid-latitude ionosphere and plasmasphere has been developed. The new model uses a new method in ionospheric and plasmaspheric simulations which is a combination of the Eulerian and Lagrangian approaches in model simulations. The electron and ion continuity and energy equations are solved in a Lagrangian frame of reference which moves with an individual parcel of plasma with the local plasma drift velocity perpendicular to the magnetic and electric fields. As a result, only the time-dependent, one-dimension electron and ion continuity and energy equations are solved in this Lagrangian frame of reference. The new method makes use of an Eulerian computational grid which is fixed in space co-ordinates and chooses the set of the plasma parcels at every time step, so that all the plasma parcels arrive at points which are located between grid lines of the regularly spaced Eulerian computational grid at the next time step. The solution values of electron and ion densities Ne and Ni and temperatures Te and Ti at the Eulerian computational grid are obtained by interpolation. Equations which determine the trajectory of the ionospheric plasma perpendicular to magnetic field lines and take into account that magnetic field lines are "frozen" in the ionospheric plasma are derived and included in the new model. We have presented a comparison between the modeled NmF2 and hmF2 and NmF2 and hmF2 which were observed at the anomaly crest and close to the geomagnetic equator simultaneously by the Huancayo, Chiclayo, Talara, Bogota, Panama, and Puerto Rico ionospheric sounders during the 7 October 1957 geomagnetically quiet time period at solar maximum. The model calculations show that there is a need to revise the model local time dependence of the equatorial upward E × B drift velocity given by Scherliess and Fejer (1999 at solar maximum during quiet

  2. The viscosity and density of sour gas fluids at high temperatures and high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Giri, B.R.; Marriott, R.A.; Blais, P.; Clark, P.D. [Alberta Sulphur Research Ltd., Calgary, AB (Canada); Calgary Univ., AB (Canada). Dept. of Chemistry

    2010-01-15

    This poster session discussed an experiment designed to measure the viscosity and density of sour gas fluids at high temperatures and pressures. An option for disposing acid gases while enhancing the production of oil and gas fields is the re-injection of gases rich in hydrogen sulphide/carbon dioxide (H{sub 2}S/CO{sub 2}) into reservoirs up to very high pressures, but issues with respect to corrosion, compression, pumping, and transport need addressing, and the reliable high-density/high-pressure data needed to arrive at an optimum process concept and the design of pumps, compressors, and transport lines had up to this point been lacking. The experimental set up involved the use of a Vibrating Tube Densimeter and a Cambridge Viscometer. Working with toxic gases at very high pressures and obtaining highly accurate data in a wide range of conditions were two of the challenges faced during the experiment. The experiment resulted in physical property measurement systems being recalibrated and a new daily calibration routine being adopted for accuracy. The densities and viscosities of pure CO{sub 2} and sulphur dioxide (SO{sub 2}) in a wide pressure and temperature range were determined. 1 tab., 9 figs.

  3. [Effects of water temperature and edible algal density on the population dynamics and sexual reproduction of Moina irrasa].

    Science.gov (United States)

    Li, Yu-Ying; Deng, Dao-Gui; Lei, Juan; Xi, Yi-Long

    2011-12-01

    This paper studied the population dynamics and sexual reproduction of Moina irrasa at different water temperature and edible algal density. The population density of M. irrasa was obviously higher at high than at medium and low densities of edible algae, with the maximum at high edible algal density and 20 degrees C. At the same temperatures, the average number of the offsprings first produced by per female M. irrasa declined with decreasing edible algal density, and the maximum value appeared at 25 degrees C and at high edible algal density. The male offsprings produced were obviously higher at high than at medium and low edible algal densities. There was a significant correlation between the male density and the population density of M. irrasa. The number of ephippia produced by M. irrasa declined with decreasing edible algal density, and was higher at 25 degrees C than at other temperatures. Edible algal density had larger effects on the population dynamics and sexual reproduction of M. irrasa, as compared with temperature.

  4. The effect of wind velocity, air temperature and humidity on NH 3 and SO 2 transfer into bean leaves ( phaseolus vulgaris L.)

    Science.gov (United States)

    van Hove, L. W. A.; Vredenberg, W. J.; Adema, E. H.

    The influence of wind velocity, air temperature and vapour pressure deficit of the air (VPD) on NH 3 and SO 2 transfer into bean leaves ( Phaseolus vulgaris L.) was examined using a leaf chamber. The measurements suggested a transition in the properties of the leaf boundary layer at a wind velocity of 0.3-0.4 ms -1 which corresponds to a Recrit value of about 2000. At higher wind velocities the leaf boundary layer resistance ( rb) was 1.5-2 times lower than can be calculated from the theory. Nevertheless, the assessed relationships between rb and wind velocity appeared to be similar to the theoretical derived relationship for rb. The NH 3 flux and in particular the SO 2 flux into the leaf strongly increased at a VPD decline. The increase of the NH 3 flux could be attributed to an increase of the stomatal conductance ( gs). However, the increase of the SO 2 flux could only partly be explained by an increase of gs. An apparent additional uptake was also observed for the NH 3 uptake at a low temperature and VPD. The SO 2 flux was also influenced by air temperature which could be explained by a temperature effect on gs. The results suggest that calculation of the NH 3 and SO 2 flux using data of gs gives a serious understimation of the real flux of these gases into leaves at a low temperature and VPD.

  5. High Energy Density and High Temperature Multilayer Capacitor Films for Electric Vehicle Applications

    Science.gov (United States)

    Treufeld, Imre; Song, Michelle; Zhu, Lei; Baer, Eric; Snyder, Joe; Langhe, Deepak

    2015-03-01

    Multilayer films (MLFs) with high energy density and high temperature capability (>120 °C) have been developed at Case Western Reserve University. Such films offer a potential solution for electric car DC-link capacitors, where high ripple currents and high temperature tolerance are required. The current state-of-the-art capacitors used in electric cars for converting DC to AC use biaxially oriented polypropylene (BOPP), which can only operate at temperatures up to 85 °C requiring an external cooling system. The polycarbonate (PC)/poly(vinylidene fluoride) (PVDF) MLFs have a higher permittivity compared to that of BOPP (2.3), leading to higher energy density. They have good mechanical stability and reasonably low dielectric losses at 120 °C. Nonetheless, our preliminary dielectric measurements show that the MLFs exhibit appreciable dielectric losses (20%) at 120 °C, which would, despite all the other advantages, make them not suitable for practical applications. Our preliminary data showed that dielectric losses of the MLFs at 120 °C up to 400 MV/m and 1000 Hz originate mostly from impurity ionic conduction. This work is supported by the NSF PFI/BIC Program (IIP-1237708).

  6. Light-front Nambu--Jona-Lasinio model at finite temperature and density

    CERN Document Server

    Strauss, S; Beyer, M

    2009-01-01

    In recent years light-front quantisation has been extended to allow for a consistent treatment of systems at finite temperature and density. This is in particular interesting for an investigation of the processes in nuclear matter under extreme condition as occurring, e.g., during a heavy ion collision. Utilising a Dyson expansion to the N-point Green functions at finite temperature and density we focus on the occurrence of pionic and scalar diquark dynamics in quark matter and compute the masses and the Mott dissociation using a separable t-matrix approach. For the scalar quark-quark correlation we determine the critical temperature of colour superconductivity using the Thouless criterion. On the same footing the properties of the nucleon in a medium of quark matter are computed within a Faddeev approach. Critical lines for nucleon breakup are given. Presently, we use a light-front Nambu--Jona-Lasinio model that allows us to compare these results of this novel approach to the more traditional instant form ap...

  7. Dependence of the critical temperature in overdoped copper oxides on superfluid density

    Science.gov (United States)

    Božović, I.; He, X.; Wu, J.; Bollinger, A. T.

    2016-08-01

    The physics of underdoped copper oxide superconductors, including the pseudogap, spin and charge ordering and their relation to superconductivity, is intensely debated. The overdoped copper oxides are perceived as simpler, with strongly correlated fermion physics evolving smoothly into the conventional Bardeen-Cooper-Schrieffer behaviour. Pioneering studies on a few overdoped samples indicated that the superfluid density was much lower than expected, but this was attributed to pair-breaking, disorder and phase separation. Here we report the way in which the magnetic penetration depth and the phase stiffness depend on temperature and doping by investigating the entire overdoped side of the La2-xSrxCuO4 phase diagram. We measured the absolute values of the magnetic penetration depth and the phase stiffness to an accuracy of one per cent in thousands of samples; the large statistics reveal clear trends and intrinsic properties. The films are homogeneous; variations in the critical superconducting temperature within a film are very small (less than one kelvin). At every level of doping the phase stiffness decreases linearly with temperature. The dependence of the zero-temperature phase stiffness on the critical superconducting temperature is generally linear, but with an offset; however, close to the origin this dependence becomes parabolic. This scaling law is incompatible with the standard Bardeen-Cooper-Schrieffer description.

  8. Thiolated gold nanoparticle solvation in near-critical fluids: The role of density, temperature, and topology

    Science.gov (United States)

    Yadav, Hari O. S.; Chakravarty, Charusita

    2017-05-01

    We employ molecular dynamics simulations to study the structure and solvation thermodynamics of thiolated gold nanoparticles of size 1.2 and 1.6 nm with ligand of chain length 8-16 carbons in ethane and propane over a wide range of densities close to the critical isotherm. The Helmholtz free energy is estimated by explicitly calculating the change in entropy and internal energy of solvation, and the effect of density and temperature on fluctuation-driven inherent anisotropy in the ligand corona is characterized. Since the topological variation further accentuates this instantaneous asymmetry in the ligand cloud, the anisotropy with varying surface coverage and chain length is also studied including the solvent contributions to the entropic and energetic metrics. Our results are consistent with the experiment, suggesting a route of obtaining structural insights into solvation thermodynamics that could be useful for understanding the stability of nanoparticle dispersions.

  9. Nuclear matter symmetry energy from generalized polarizabilities: dependences on momentum, isospin, density and temperature

    CERN Document Server

    Braghin, F L

    2004-01-01

    Symmetry energy terms from macroscopic mass formulae are investigated as generalized polarizabilities of nuclear matter. Besides the neutron-proton (n-p) symmetry energy the spin dependent symmetry energies and a scalar one are also defined. They depend on the nuclear densities ($\\rho$), neutron-proton asymmetry ($b$), temperature ($T$) and exchanged energy and momentum ($q$). Based on a standard expression for the generalized polarizabilities, a differential equation is proposed to constrain the dependence of the symmetry energy on the n-p asymmetry and on the density. Some solutions are discussed. The q-dependence (zero frequence) of the symmetry energy coefficients with Skyrme-type forces is investigated in the four channels of the particle-hole interaction. Spin dependent symmetry energies are also investigated indicating much stronger differences in behavior with $q$ for each Skyrme force than the results for the neutron-proton one.

  10. Measurements of Ionospheric Density, Temperature, and Spacecraft Charging in a Space Weather Constellation

    Science.gov (United States)

    Balthazor, R. L.; McHarg, M. G.; Wilson, G.

    2016-12-01

    The Integrated Miniaturized Electrostatic Analyzer (IMESA) is a space weather sensor developed by the United States Air Force Academy and integrated and flown by the DoD's Space Test Program. IMESA records plasma spectrograms from which can be derived plasma density, temperature, and spacecraft frame charging. Results from IMESA currently orbiting on STPSat-3 are presented, showing frame charging effects dependent on a complex function of the number of solar panel cell strings switched in, solar panel current, and plasma density. IMESA will fly on four more satellites launching in the next two calendar years, enabling an undergraduate DoD space weather constellation in Low Earth Orbit that has the ability to significantly improve space weather forecasting capabilities using assimilative forecast models.

  11. Histograms in heavy-quark QCD at finite temperature and density

    CERN Document Server

    Saito, H; Aoki, S; Kanaya, K; Nakagawa, Y; Ohno, H; Okuno, K; Umeda, T

    2013-01-01

    We study the phase structure of lattice QCD with heavy quarks at finite temperature and density by a histogram method. We determine the location of the critical point at which the first-order deconfining transition in the heavy-quark limit turns into a crossover at intermediate quark masses through a change of the shape of the histogram under variation of coupling parameters. We estimate the effect of the complex phase factor which causes the sign problem at finite density, and show that, in heavy-quark QCD, the effect is small around the critical point. We determine the critical surface in 2+1 flavor QCD in the heavy-quark region at all values of the chemical potential mu including mu=infty.

  12. Sensitivity Analysis of Flow and Temperature Distributions of Density Currents in a River-Reservoir System under Upstream Releases with Different Durations

    Directory of Open Access Journals (Sweden)

    Gang Chen

    2015-11-01

    Full Text Available A calibrated three-dimensional Environmental Fluid Dynamics Code model was applied to simulate unsteady flow patterns and temperature distributions in the Bankhead river-reservoir system in Alabama, USA. A series of sensitivity model runs were performed under daily repeated large releases (DRLRs with different durations (2, 4 and 6 h from Smith Dam Tailrace (SDT when other model input variables were kept unchanged. The density currents in the river-reservoir system form at different reaches, are destroyed at upstream locations due to the flow momentum of the releases, and form again due to solar heating. DRLRs (140 m3/s with longer durations push the bottom cold water further downstream and maintain a cooler bottom water temperature. For the 6-h DRLR, the momentum effect definitely reaches Cordova (~43.7 km from SDT. Positive bottom velocity (density currents moving downstream is achieved 48.4%, 69.0% and 91.1% of the time with an average velocity of 0.017, 0.042 and 0.053 m/s at Cordova for the 2-h, 4-h and 6-h DRLR, respectively. Results show that DRLRs lasting for at least 4 h maintain lower water temperatures at Cordova. When the 4-h and 6-h DRLRs repeat for more than 6 and 10 days, respectively, bottom temperatures at Cordova become lower than those for the constant small release (2.83 m3/s. These large releases overwhelm the mixing effects due to inflow momentum and maintain temperature stratification at Cordova.

  13. Combined temperature and density series for fluid-phase properties. I. Square-well spheres

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, J. Richard [Chemical and Biomolecular Engineering Department, The University of Akron, Akron, Ohio 44325-3906 (United States); Schultz, Andrew J.; Kofke, David A. [Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-4200 (United States)

    2015-09-21

    Cluster integrals are evaluated for the coefficients of the combined temperature- and density-expansion of pressure: Z = 1 + B{sub 2}(β) η + B{sub 3}(β) η{sup 2} + B{sub 4}(β) η{sup 3} + ⋯, where Z is the compressibility factor, η is the packing fraction, and the B{sub i}(β) coefficients are expanded as a power series in reciprocal temperature, β, about β = 0. The methodology is demonstrated for square-well spheres with λ = [1.2-2.0], where λ is the well diameter relative to the hard core. For this model, the B{sub i} coefficients can be expressed in closed form as a function of β, and we develop appropriate expressions for i = 2-6; these expressions facilitate derivation of the coefficients of the β series. Expanding the B{sub i} coefficients in β provides a correspondence between the power series in density (typically called the virial series) and the power series in β (typically called thermodynamic perturbation theory, TPT). The coefficients of the β series result in expressions for the Helmholtz energy that can be compared to recent computations of TPT coefficients to fourth order in β. These comparisons show good agreement at first order in β, suggesting that the virial series converges for this term. Discrepancies for higher-order terms suggest that convergence of the density series depends on the order in β. With selection of an appropriate approximant, the treatment of Helmholtz energy that is second order in β appears to be stable and convergent at least to the critical density, but higher-order coefficients are needed to determine how far this behavior extends into the liquid.

  14. Combined temperature and density series for fluid-phase properties. I. Square-well spheres

    Science.gov (United States)

    Elliott, J. Richard; Schultz, Andrew J.; Kofke, David A.

    2015-09-01

    Cluster integrals are evaluated for the coefficients of the combined temperature- and density-expansion of pressure: Z = 1 + B2(β) η + B3(β) η2 + B4(β) η3 + ⋯, where Z is the compressibility factor, η is the packing fraction, and the Bi(β) coefficients are expanded as a power series in reciprocal temperature, β, about β = 0. The methodology is demonstrated for square-well spheres with λ = [1.2-2.0], where λ is the well diameter relative to the hard core. For this model, the Bi coefficients can be expressed in closed form as a function of β, and we develop appropriate expressions for i = 2-6; these expressions facilitate derivation of the coefficients of the β series. Expanding the Bi coefficients in β provides a correspondence between the power series in density (typically called the virial series) and the power series in β (typically called thermodynamic perturbation theory, TPT). The coefficients of the β series result in expressions for the Helmholtz energy that can be compared to recent computations of TPT coefficients to fourth order in β. These comparisons show good agreement at first order in β, suggesting that the virial series converges for this term. Discrepancies for higher-order terms suggest that convergence of the density series depends on the order in β. With selection of an appropriate approximant, the treatment of Helmholtz energy that is second order in β appears to be stable and convergent at least to the critical density, but higher-order coefficients are needed to determine how far this behavior extends into the liquid.

  15. A Tall-Tower Instrument for Mean and Fluctuating Velocity, Fluctuating Temperature and Sensible Heat Flux Measurements

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Thomson, D. W.

    1979-01-01

    For an ongoing elevated-source, urban-scale tracer experiment, an instrument system to measure the three-dimensional wind velocity and the turbulent sensible heat flux was developed. The wind velocity was measured with a combination of cup anemometer, propeller (vertical) and vane sensor. The tem......For an ongoing elevated-source, urban-scale tracer experiment, an instrument system to measure the three-dimensional wind velocity and the turbulent sensible heat flux was developed. The wind velocity was measured with a combination of cup anemometer, propeller (vertical) and vane sensor...

  16. Shape evolution of 72,74Kr with temperature in covariant density functional theory

    Science.gov (United States)

    Zhang, Wei; Niu, Yi-Fei

    2017-09-01

    The rich phenomena of deformations in neutron-deficient krypton isotopes, such as shape evolution with neutron number and shape coexistence, have attracted the interest of nuclear physicists for decades. It is interesting to study such shape phenomena using a novel way, e.g. by thermally exciting the nucleus. In this work, we develop the finite temperature covariant density functional theory for axially deformed nuclei with the treatment of pairing correlations by the BCS approach, and apply this approach for the study of shape evolution in 72,74Kr with increasing temperature. For 72Kr, with temperature increasing, the nucleus firstly experiences a relatively quick weakening in oblate deformation at temperature T ∼0.9 MeV, and then changes from oblate to spherical at T ∼2.1 MeV. For 74Kr, its global minimum is at quadrupole deformation β2 ∼ ‑0.14 and abruptly changes to spherical at T∼ 1.7 MeV. The proton pairing transition occurs at critical temperature 0.6 MeV following the rule Tc=0.6Δp(0), where Δp(0) is the proton pairing gap at zero temperature. The signatures of the above pairing transition and shape changes can be found in the specific heat curve. The single-particle level evolutions with temperature are presented. Supported by National Natural Science Foundation of China (11105042, 11305161, 11505157), Open Fund of Key Laboratory of Time and Frequency Primary Standards, CAS, and Support from Henan Administration of Foreign Experts Affairs

  17. LEVEL DENSITY AND FINITE-TEMPERATURE SPECIFIC HEATOF NUCLEUS 104pd UNDER MICROSCOPIC IBM

    Institute of Scientific and Technical Information of China (English)

    石筑一; 刘庸; 桑建平

    2001-01-01

    By using the microscopic sdgIBM-Fmax approach, the procedure of canonical ensemble average and the saddle point approximation, the thermodynamics of the nucleus is established under microscopic IBM. Calculations of spectrum, level density and finite-temperature specific heat for the nucleus 104pd are carried out. The calculated values are coincident with the experimental data reported recently. The results predict that the shape phase transition in the groundstate band appears at about T ≈0.230MeV and the phase transition of the thermal excitation mode takes place at T ≈0.630 MeV for the nucleus 104pd.

  18. Probing Ionic Liquid Aqueous Solutions Using Temperature of Maximum Density Isotope Effects

    Directory of Open Access Journals (Sweden)

    Mohammad Tariq

    2013-03-01

    Full Text Available This work is a new development of an extensive research program that is investigating for the first time shifts in the temperature of maximum density (TMD of aqueous solutions caused by ionic liquid solutes. In the present case we have compared the shifts caused by three ionic liquid solutes with a common cation—1-ethyl-3-methylimidazolium coupled with acetate, ethylsulfate and tetracyanoborate anions—in normal and deuterated water solutions. The observed differences are discussed in terms of the nature of the corresponding anion-water interactions.

  19. Electron Density and Temperature Measurements, and Abundance Anomalies in the Solar Atmosphere

    Indian Academy of Sciences (India)

    Anita Mohan; Bhola N. Dwivedi; Enrico Landi

    2000-09-01

    Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height above an active region observed at the solar limb, with emphasis on the so-called transition region lines.

  20. Fitting of the Thomson scattering density and temperature profiles on the COMPASS tokamak

    Science.gov (United States)

    Stefanikova, E.; Peterka, M.; Bohm, P.; Bilkova, P.; Aftanas, M.; Sos, M.; Urban, J.; Hron, M.; Panek, R.

    2016-11-01

    A new technique for fitting the full radial profiles of electron density and temperature obtained by the Thomson scattering diagnostic in H-mode discharges on the COMPASS tokamak is described. The technique combines the conventionally used modified hyperbolic tangent function for the edge transport barrier (pedestal) fitting and a modification of a Gaussian function for fitting the core plasma. Low number of parameters of this combined function and their straightforward interpretability and controllability provide a robust method for obtaining physically reasonable profile fits. Deconvolution with the diagnostic instrument function is applied on the profile fit, taking into account the dependence on the actual magnetic configuration.

  1. Systematic measurements of opacity dependence on temperature, density, and atomic number at stellar interior conditions

    Science.gov (United States)

    Bailey, James; Nagayama, T.; Loisel, G. P.; Rochau, G. A.; Blancard, C.; Colgan, J.; Cosse, Ph.; Faussurier, G.; Fontes, C. J.; Golovkin, I.; Hansen, S. B.; Iglesias, C. A.; Kilcrease, D. P.; Macfarlane, J. J.; Mancini, R. C.; Nahar, S. N.; Orban, C.; Pradhan, A. K.; Sherrill, M.; Wilson, B. G.; Pain, J. C.; Gilleron, F.

    2016-10-01

    Model predictions for iron opacity are notably different from measurements performed at conditions similar to the boundary between the solar radiation and convection zone. New measurements at the Sandia Z facility with chromium, iron, and nickel are providing a systematic study of how opacity changes with temperature, density, and atomic number. These measurements help further evaluate possibilities for experiment errors and help constrain hypotheses for opacity model refinements. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  2. Anomalous temperature dependence of liquid state density for Ni50Ti50 alloy investigated under electrostatic levitation state

    Science.gov (United States)

    Zou, P. F.; Wang, H. P.; Yang, S. J.; Hu, L.; Wei, B.

    2017-08-01

    The density of liquid Ni-Ti alloys were measured by electrostatic levitation technique and the maximum reduced undercooling of ΔT/TL reaches 0.23. Quite different from the linear relationship between density and temperature for liquid Ni45Ti55 and Ni55Ti45 alloys, the density of liquid Ni50Ti50 alloy displays a nonlinear dependence on temperature. Interestingly, the density increasing tendency of liquid Ni50Ti50 alloy rises more rapidly with the decrease of temperature, which results from the more severe shrinking of the distance among atoms at lower temperatures. In addition, the thermal expansion coefficient of liquid Ni50Ti50 alloy increases linearly with the decrease of temperature.

  3. Compensating effect of sap velocity for stand density leads to uniform hillslope-scale forest transpiration across a steep valley cross-section

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel

    2016-04-01

    Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.

  4. Direct Measurements of the Spatial and Velocity Dependence of the Ion Density Fluctuation Spectrum of a Laboratory Plasma with Two Independent LIF Schemes

    Science.gov (United States)

    Mattingly, Sean; Berumen, Jorge; Chu, Feng; Hood, Ryan; Skiff, Fred

    2014-10-01

    By using two independently tunable lasers, each with its own collection optics and Ar II LIF transition scheme, we are able to investigate plasma ion density fluctuations as a function of not only spatial scales but also as a function of ion velocities as sampled on different points of a single Doppler-broadened spectral emission line. We do this by measuring the two point correlation C (x , v ,x' ,v' , τ) = t . With the current system, the two carriages determine x and x', while the velocities selected by each laser determine v and v'. Using the two lasers to make two point correlations in phase space demonstrates effects that are not fully understood. In this experiment, we explore the striking difference in correlations when, in the past, the particle orbits overlap in space versus when they do not overlap. This is performed on a small cylindrical laboratory plasma with n ~109 cm-3 , Te ~ 5 eV, Ti ~ 0 . 06 , and a 1 kG axial magnetic field. LIF is performed on ions at two locations aligned with the magnetic field line with a viewing volume comparable to the size of the Larmor radius. Results and interpretations from these experiments are presented and discussed. DOE Grant DE-FG02-99ER54543.

  5. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature.

    Science.gov (United States)

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-11-22

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch(-2), ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

  6. Renormalization effects and phonon density of states in high temperature superconductors

    Directory of Open Access Journals (Sweden)

    Vinod Ashokan

    2013-02-01

    Full Text Available Using the versatile double time thermodynamic Green's function approach based on many body theory the renormalized frequencies, phonon energy line widths, shifts and phonon density of states (PDOS are investigated via a newly formulated Hamiltonian (does not include BCS type Hamiltonian that includes the effects of electron-phonon, anharmonicities and that of isotopic impurities. The automatic appearance of pairons, temperature, impurity and electron-phonon coupling of renormalized frequencies, widths, shifts and PDOS emerges as a characteristic feature of present theory. The numerical investigations on PDOS for the YBa2Cu3O7 − δ crystal predicts several new feature of high temperature superconductors (HTS and agreements with experimental observations.

  7. Low Temperature Performance of High Power Density DC/DC Converter Modules

    Science.gov (United States)

    Elbuluk, Malik E.; Hammond, Ahmad; Gerber, Scott; Patterson, Richard L.; Overton, Eric

    2001-01-01

    In this paper, two second-generation high power density DC/DC converter modules have been evaluated at low operating temperatures. The power rating of one converter (Module 1) was specified at 150 W with an input voltage range of 36 to 75 V and output voltage of 12 V. The other converter (Module 2) was specified at 100 W with the same input voltage range and an output voltage of 3.3 V. The converter modules were evaluated in terms of their performance as a function of operating temperature in the range of 25 to -140 C. The experimental procedures along with the experimental data obtained are presented and discussed in this paper.

  8. Kinetic temperature and density of the Sagittarius B2 molecular cloud from observations of methyl cyanide

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, S.E.; Green, S.; Thaddeus, P.; Linke, R.A.

    1983-03-01

    From observations with the Bell Laboratories 7 m telescope of the K components of the CH/sub 3/CH J = 4..-->..3 rotational transition at 73.6 GHz, 6..-->..5 transition at 110.4 GHz, and 7..-->..6 transition at 128.7 GHz, a mean kinetic temperature of 85 +- 10 K and a mean H/sub 2/ density of (1.1 +- 0.5) x 10/sup 5/ cm/sup -3/ are deduced for the central 2' of the Sgr B2 molecular cloud. Within the K = 0--4 ladders of CH/sub 3/CN in Sgr B2 the populations of the radiatively coupled J levels are relaxed, with a rotational temperature of approximately 16 K: similar to that of several linear molecules.

  9. High Temperature, high pressure equation of state density correlations and viscosity correlations

    Energy Technology Data Exchange (ETDEWEB)

    Tapriyal, D.; Enick, R.; McHugh, M.; Gamwo, I.; Morreale, B.

    2012-07-31

    Global increase in oil demand and depleting reserves has derived a need to find new oil resources. To find these untapped reservoirs, oil companies are exploring various remote and harsh locations such as deep waters in Gulf of Mexico, remote arctic regions, unexplored deep deserts, etc. Further, the depth of new oil/gas wells being drilled has increased considerably to tap these new resources. With the increase in the well depth, the bottomhole temperature and pressure are also increasing to extreme values (i.e. up to 500 F and 35,000 psi). The density and viscosity of natural gas and crude oil at reservoir conditions are critical fundamental properties required for accurate assessment of the amount of recoverable petroleum within a reservoir and the modeling of the flow of these fluids within the porous media. These properties are also used to design appropriate drilling and production equipment such as blow out preventers, risers, etc. With the present state of art, there is no accurate database for these fluid properties at extreme conditions. As we have begun to expand this experimental database it has become apparent that there are neither equations of state for density or transport models for viscosity that can be used to predict these fundamental properties of multi-component hydrocarbon mixtures over a wide range of temperature and pressure. Presently, oil companies are using correlations based on lower temperature and pressure databases that exhibit an unsatisfactory predictive capability at extreme conditions (e.g. as great as {+-} 50%). From the perspective of these oil companies that are committed to safely producing these resources, accurately predicting flow rates, and assuring the integrity of the flow, the absence of an extensive experimental database at extreme conditions and models capable of predicting these properties over an extremely wide range of temperature and pressure (including extreme conditions) makes their task even more daunting.

  10. Provide a suitable range to include the thermal creeping effect on slip velocity and temperature jump of an air flow in a nanochannel by lattice Boltzmann method

    Science.gov (United States)

    Karimipour, Arash

    2017-01-01

    The thermal creeping effect on slip velocity of air forced convection through a nanochannel is studied for the first time by using a lattice Boltzmann method. The nanochannel side walls are kept hot while the cold inlet air streams along them. The computations are presented for the wide range of Reynolds number, Knudsen number and Eckert number while slip velocity and temperature jump effects are involved. Moreover appropriate validations are performed versus previous works concerned the micro-nanoflows. The achieved results are shown as the velocity and temperature profiles at different cross sections, streamlines and isotherms and also the values of slip velocity and temperature jump along the nanochannel walls. The ability of the lattice Boltzmann method to simulate the thermal creeping effects on hydrodynamic and thermal domains of flow is shown at this study; so that its effects should be involved at lower values of Eckert number and higher values of Reynolds number especially at entrance region where the most temperature gradient exists.

  11. Viscosity and not biological mechanisms often controls the effects of temperature on ciliary activity and swimming velocity of small aquatic organisms

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Riisgård, H. U.

    2009-01-01

    A number of studies have shown that temperature-dependent viscosity of the ambient water controls or strongly affects bio-mechanical activity such as beat frequency of water-pumping cilia in mussels and ascidians, swimming velocity of sperm cells, ciliates and small (micro- and meso-scale) aquatic...

  12. Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines

    Directory of Open Access Journals (Sweden)

    P. Guio

    Full Text Available The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of the ambient electrons is modelled by a near-Maxwellian distribution function in presence of a temperature gradient and a potential electric field. The velocity distribution function of the suprathermal electrons is derived from a numerical model of the angular energy flux spectrum obtained by solving the transport equation of electrons. The numerical method used to calculate the plasma dispersion function and the reduced velocity distribution is described. The numerical code is used with simulated data to evaluate the Doppler frequency asymmetry between the up- and downshifted plasma lines of the incoherent-scatter plasma lines at different wave vectors. It is shown that the observed Doppler asymmetry is more dependent on deviation from the Maxwellian through the thermal part for high-frequency radars, while for low-frequency radars the Doppler asymmetry depends more on the presence of a suprathermal population. It is also seen that the full evaluation of the plasma dispersion function gives larger Doppler asymmetry than the heat flow approximation for Langmuir waves with phase velocity about three to six times the mean thermal velocity. For such waves the moment expansion of the dispersion function is not fully valid and the full calculation of the dispersion function is needed.

    Key words. Non-Maxwellian electron velocity distribution · Incoherent scatter plasma lines · EISCAT · Dielectric response function

  13. Far-Infrared Dust Temperatures and Column Densities of the MALT90 Molecular Clump Sample

    CERN Document Server

    Guzmán, Andrés E; Contreras, Yanett; Smith, Howard A; Jackson, James M; Hoq, Sadia; Rathborne, Jill M

    2015-01-01

    We present dust column densities and dust temperatures for $\\sim3000$ young high-mass molecular clumps from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey, derived from adjusting single temperature dust emission models to the far-infrared intensity maps measured between 160 and 870 \\micron\\ from the Herschel/Hi-Gal and APEX/ATLASGAL surveys. We discuss the methodology employed in analyzing the data, calculating physical parameters, and estimating their uncertainties. The population average dust temperature of the clumps are: $16.8\\pm0.2$ K for the clumps that do not exhibit mid-infrared signatures of star formation (Quiescent clumps), $18.6\\pm0.2$ K for the clumps that display mid-infrared signatures of ongoing star formation but have not yet developed an HII region (Protostellar clumps), and $23.7\\pm0.2$ and $28.1\\pm0.3$ K for clumps associated with HII and photo-dissociation regions, respectively. These four groups exhibit large overlaps in their temperature distributions, with dispersions rang...

  14. Effective theory for heavy quark QCD at finite temperature and density with stochastic quantization

    Energy Technology Data Exchange (ETDEWEB)

    Neuman, Mathias

    2015-07-01

    In this thesis we presented the derivation as well as the numerical and analytical treatment of an effective theory for lattice Quantum Chromodynamics (LQCD). We derived the effective theory directly from LQCD, which allows us to systematically introduce further improvements. The derivation was performed by means of an expansion around the limit of infinite quark masses and infinite gauge coupling. Using this theory we were able to derive results in the region of large densities. This region is, due to the sign problem, inaccessible to standard LQCD approaches. Although LQCD simulations at large densities have been performed recently by applying stochastic quantization, those are still limited to lattice with low numbers of timeslices and therefor can not reach the low temperature region. Furthermore, they can not be crosschecked with Monte-Carlo simulations. Since the equivalence between stochastic quantization and Monte-Carlo is unproven for the case of finite density systems, new approaches to access the cold dense region of the QCD phase diagram are desirable. The effective theory presented in this thesis provides such an approach. We introduced continuum QCD in chapter 2. In chapter 3 we presented how LQCD, i.e. QCD in a discretized space-time, can be formulated and used as a tool to explore the non-perturbative regions of the QCD phase diagram. Special emphasis was placed on simulations at finite baryon densities and the numerical problems that arise in this region. These problems are caused by the complexification of the action and are known as the sign problem. We gave a detailed presentation of the derivation of our effective theory in chapter 4. For this we performed expansions around the limit of strong coupling and static quarks, κ=β=0, introducing corrections order by order in the expansion parameters κ and β. Truncating the theory at different orders allowed us to determine the parameter region where the convergence to full LQCD is good. The gauge

  15. Quasi-optical design for systems to diagnose the electron temperature and density fluctuations on EAST

    Science.gov (United States)

    Cao, Qifo; Liu, Yong; Zhao, Hailin; Zhou, Tianfu; Ti, Ang; Hu, Liqun

    2016-11-01

    A system to simultaneously diagnose the electron temperature and density fluctuations is proposed for Experimental Advanced Superconducting Tokamak device. This system includes a common quasi-optical antenna, a correlation electron cyclotron emission (CECE) system that is used to measure the electron temperature fluctuations and a Doppler backscattering (DBS) system that is used to measure the electron density fluctuations. The frequency range of the proposed CECE system is 108-120 GHz, and this corresponds to a radial coverage of normalized radius ((R - R0)/a, R0 = 1850 mm, a = 450 mm) from 0.2 to 0.67 for the plasma operation with a toroidal magnetic field of 2.26 T. This paper focuses on the design of the quasi-optical antenna and aims at optimizing the poloidal resolution for different frequency bands. An optimum result gives the beam radius for the CECE system of 13-15 mm and this corresponds to a wave number range of kθ < 2.4 cm-1. The beam radius is 20-30 mm for V band (50-75 GHz) and 15-20 mm for W band (75-110 GHz).

  16. Shifts in the temperature of maximum density (TMD) of ionic liquid aqueous solutions.

    Science.gov (United States)

    Tariq, M; Esperança, J M S S; Soromenho, M R C; Rebelo, L P N; Lopes, J N Canongia

    2013-07-14

    This work investigates for the first time shifts in the temperature of maximum density (TMD) of water caused by ionic liquid solutes. A vast amount of high-precision volumetric data--more than 6000 equilibrated (static) high-precision density determination corresponding to ∼90 distinct ionic liquid aqueous solutions of 28 different types of ionic liquid--allowed us to analyze the TMD shifts for different homologous series or similar sets of ionic solutes and explain the overall effects in terms of hydrophobic, electrostatic and hydrogen-bonding contributions. The differences between the observed TMD shifts in the -2 temperatures are discussed taking into account the different types of possible solute-water interactions that can modify the structure of the aqueous phase. The results also reveal different insights concerning the nature of the ions that constitute typical ionic liquids and are consistent with previous results that established hydrophobic and hydrophilic scales for ionic liquid ions based on their specific interactions with water and other probe molecules.

  17. An empirical method for estimating probability density functions of gridded daily minimum and maximum temperature

    Science.gov (United States)

    Lussana, C.

    2013-04-01

    The presented work focuses on the investigation of gridded daily minimum (TN) and maximum (TX) temperature probability density functions (PDFs) with the intent of both characterising a region and detecting extreme values. The empirical PDFs estimation procedure has been realised using the most recent years of gridded temperature analysis fields available at ARPA Lombardia, in Northern Italy. The spatial interpolation is based on an implementation of Optimal Interpolation using observations from a dense surface network of automated weather stations. An effort has been made to identify both the time period and the spatial areas with a stable data density otherwise the elaboration could be influenced by the unsettled station distribution. The PDF used in this study is based on the Gaussian distribution, nevertheless it is designed to have an asymmetrical (skewed) shape in order to enable distinction between warming and cooling events. Once properly defined the occurrence of extreme events, it is possible to straightforwardly deliver to the users the information on a local-scale in a concise way, such as: TX extremely cold/hot or TN extremely cold/hot.

  18. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    Science.gov (United States)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  19. Subduction Factory 3: An Excel worksheet and macro for calculating the densities, seismic wave speeds, and H2O contents of minerals and rocks at pressure and temperature

    Science.gov (United States)

    Hacker, Bradley R.; Abers, Geoffrey A.

    2004-01-01

    An Excel macro to calculate mineral and rock physical properties at elevated pressure and temperature is presented. The workbook includes an expandable database of physical parameters for 52 rock-forming minerals stable at high pressures and temperatures. For these minerals the elastic moduli, densities, seismic velocities, and H2O contents are calculated at any specified P and T conditions, using basic thermodynamic relationships and third-order finite strain theory. The mineral modes of suites of rocks are also specifiable, so that their predicted aggregate properties can be calculated using standard solid mixing theories. A suite of sample rock modes taken from the literature provides a useful starting point. The results of these calculations can be applied to a wide variety of geophysical questions including estimating the alteration of the oceanic crust and mantle; predicting the seismic velocities of lower-crustal xenoliths; estimating the effects of changes in mineralogy, pressure and temperature on buoyancy; and assessing the H2O content and mineralogy of subducted lithosphere from seismic observations.

  20. A simple model to predict the biodiesel blend density as simultaneous function of blend percent and temperature.

    Science.gov (United States)

    Gaonkar, Narayan; Vaidya, R G

    2016-05-01

    A simple method to estimate the density of biodiesel blend as simultaneous function of temperature and volume percent of biodiesel is proposed. Employing the Kay's mixing rule, we developed a model and investigated theoretically the density of different vegetable oil biodiesel blends as a simultaneous function of temperature and volume percent of biodiesel. Key advantage of the proposed model is that it requires only a single set of density values of components of biodiesel blends at any two different temperatures. We notice that the density of blend linearly decreases with increase in temperature and increases with increase in volume percent of the biodiesel. The lower values of standard estimate of error (SEE = 0.0003-0.0022) and absolute average deviation (AAD = 0.03-0.15 %) obtained using the proposed model indicate the predictive capability. The predicted values found good agreement with the recent available experimental data.