Shaping the distribution of vertical velocities of antihydrogen in GBAR

Energy Technology Data Exchange (ETDEWEB)

Dufour, G.; Lambrecht, A.; Reynaud, S. [CNRS, ENS, UPMC, Laboratoire Kastler-Brossel, Paris (France); Debu, P. [CEA-Saclay, Institut de Recherche sur les lois Fondamentales de l' Univers, Gif-sur-Yvette (France); Nesvizhevsky, V.V. [Institut Max von Laue-Paul Langevin, Grenoble (France); Voronin, A.Yu. [P.N. Lebedev Physical Institute, Moscow (Russian Federation)

2014-01-15

GBAR is a project aiming at measuring the freefall acceleration of gravity for antimatter, namely antihydrogen atoms (H). The precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution.We propose to use a new method for shaping the distribution of the vertical velocities of H, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing H with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk.We estimate statistical and systematic uncertainties, and we show that the accuracy for measuring the free fall acceleration g of H could be pushed below 10{sup -3} under realistic experimental conditions. (orig.)

Shaping the distribution of vertical velocities of antihydrogen in GBAR

CERN Document Server

Dufour, G.; Lambrecht, A.; Nesvizhevsky, V.V.; Reynaud, S.; Voronin, A.Yu.

2014-01-30

GBAR is a project aiming at measuring the free fall acceleration of gravity for antimatter, namely antihydrogen atoms ($\\overline{\\mathrm{H}}$). Precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution. We propose to use a new method for shaping the distribution of vertical velocities of $\\overline{\\mathrm{H}}$, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing $\\overline{\\mathrm{H}}$ with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk. We estimate statistical and systematic uncertainties, and show that the accuracy for measuring the free fall acceleration $\\overline{g}$ of $\\overline{\\mathrm{H}}$ could be pushed below $10^{-3}$ under realistic experimental conditions.

A Unified Geodetic Vertical Velocity Field (UGVVF), Version 1.0

Science.gov (United States)

Schmalzle, G.; Wdowinski, S.

2014-12-01

Tectonic motion, volcanic inflation or deflation, as well as oil, gas and water pumping can induce vertical motion. In southern California these signals are inter-mingled. In tectonics, properly identifying regions that are contaminated by other signals can be important when estimating fault slip rates. Until recently vertical deformation rates determined by high precision Global Positioning Systems (GPS) had large uncertainties compared to horizontal components and were rarely used to constrain tectonic models of fault motion. However, many continuously occupied GPS stations have been operating for ten or more years, often delivering uncertainties of ~1 mm/yr or less, providing better constraints for tectonic modeling. Various processing centers produced GPS time series and estimated vertical velocity fields, each with their own set of processing techniques and assumptions. We compare vertical velocity solutions estimated by seven data processing groups as well as two combined solutions (Figure 1). These groups include: Central Washington University (CWU) and New Mexico Institute of Technology (NMT), and their combined solution provided by the Plate Boundary Observatory (PBO) through the UNAVCO website. Also compared are the Jet Propulsion Laboratory (JPL) and Scripps Orbit and Permanent Array Center (SOPAC) and their combined solution provided as part of the NASA MEaSUREs project. Smaller velocity fields included are from Amos et al., 2014, processed at the Nevada Geodetic Laboratory, Shen et al., 2011, processed by UCLA and called the Crustal Motion Map 4.0 (CMM4) dataset, and a new velocity field provided by the University of Miami (UM). Our analysis includes estimating and correcting for systematic vertical velocity and uncertainty differences between groups. Our final product is a unified velocity field that contains the median values of the adjusted velocity fields and their uncertainties. This product will be periodically updated when new velocity fields

Vertical grid of retrieved atmospheric profiles

International Nuclear Information System (INIS)

Ceccherini, Simone; Carli, Bruno; Raspollini, Piera

2016-01-01

The choice of the vertical grid of atmospheric profiles retrieved from remote sensing observations is discussed considering the two cases of profiles used to represent the results of individual measurements and of profiles used for subsequent data fusion applications. An ozone measurement of the MIPAS instrument is used to assess, for different vertical grids, the quality of the retrieved profiles in terms of profile values, retrieval errors, vertical resolutions and number of degrees of freedom. In the case of individual retrievals no evident advantage is obtained with the use of a grid finer than the one with a reduced number of grid points, which are optimized according to the information content of the observations. Nevertheless, this instrument dependent vertical grid, which seems to extract all the available information, provides very poor results when used for data fusion applications. A loss of about a quarter of the degrees of freedom is observed when the data fusion is made using the instrument dependent vertical grid relative to the data fusion made using a vertical grid optimized for the data fusion product. This result is explained by the analysis of the eigenvalues of the Fisher information matrix and leads to the conclusion that different vertical grids must be adopted when data fusion is the expected application. - Highlights: • Data fusion application is taken into account for the choice of the vertical grid. • The study is performed using ozone profiles retrieved from MIPAS measurements. • A very fine vertical grid is not needed for the analysis of a single instrument. • The instrument dependent vertical grid is not the best choice for data fusion. • A data fusion dependent vertical grid must be used for profiles that will be fused.

Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions

Directory of Open Access Journals (Sweden)

R. Calmer

2018-05-01

Full Text Available The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA. In atmospheric research, lightweight RPAs ( <  2.5 kg are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol–cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol–cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS. The five-hole probe is calibrated on a multi-axis platform, and the probe–INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD functions and turbulent kinetic energy (TKE derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland, a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological

Radial velocity asymmetries from jets with variable velocity profiles

International Nuclear Information System (INIS)

Cerqueira, A. H.; Vasconcelos, M. J.; Velazquez, P. F.; Raga, A. C.; De Colle, F.

2006-01-01

We have computed a set of 3-D numerical simulations of radiatively cooling jets including variabilities in both the ejection direction (precession) and the jet velocity (intermittence), using the Yguazu-a code. In order to investigate the effects of jet rotation on the shape of the line profiles, we also introduce an initial toroidal rotation velocity profile. Since the Yguazu-a code includes an atomic/ionic network, we are able to compute the emission coefficients for several emission lines, and we generate line profiles for the Hα, [O I]λ6300, [S II]λ6716 and [N II]λ6548 lines. Using initial parameters that are suitable for the DG Tau microjet, we show that the computed radial velocity shift for the medium-velocity component of the line profile as a function of distance from the jet axis is strikingly similar for rotating and non-rotating jet models

Measurement system of bubbly flow using ultrasonic velocity profile monitor and video data processing unit

International Nuclear Information System (INIS)

Aritomi, Masanori; Zhou, Shirong; Nakajima, Makoto; Takeda, Yasushi; Mori, Michitsugu; Yoshioka, Yuzuru.

1996-01-01

The authors have been developing a measurement system for bubbly flow in order to clarify its multi-dimensional flow characteristics and to offer a data base to validate numerical codes for multi-dimensional two-phase flow. In this paper, the measurement system combining an ultrasonic velocity profile monitor with a video data processing unit is proposed, which can measure simultaneously velocity profiles in both gas and liquid phases, a void fraction profile for bubbly flow in a channel, and an average bubble diameter and void fraction. Furthermore, the proposed measurement system is applied to measure flow characteristics of a bubbly countercurrent flow in a vertical rectangular channel to verify its capability. (author)

Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones

Science.gov (United States)

Monteiro, Martín; Martí, Arturo C.

2017-01-01

We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are…

Remote determination of the velocity index and mean streamwise velocity profiles

Science.gov (United States)

Johnson, E. D.; Cowen, E. A.

2017-09-01

When determining volumetric discharge from surface measurements of currents in a river or open channel, the velocity index is typically used to convert surface velocities to depth-averaged velocities. The velocity index is given by, k=Ub/Usurf, where Ub is the depth-averaged velocity and Usurf is the local surface velocity. The USGS (United States Geological Survey) standard value for this coefficient, k = 0.85, was determined from a series of laboratory experiments and has been widely used in the field and in laboratory measurements of volumetric discharge despite evidence that the velocity index is site-specific. Numerous studies have documented that the velocity index varies with Reynolds number, flow depth, and relative bed roughness and with the presence of secondary flows. A remote method of determining depth-averaged velocity and hence the velocity index is developed here. The technique leverages the findings of Johnson and Cowen (2017) and permits remote determination of the velocity power-law exponent thereby, enabling remote prediction of the vertical structure of the mean streamwise velocity, the depth-averaged velocity, and the velocity index.

Post-midnight equatorial irregularity distributions and vertical drift velocity variations during solstices

Science.gov (United States)

Su, S.-Y.; Liu, C. H.; Chao, C.-K.

2018-04-01

Longitudinal distributions of post-midnight equatorial ionospheric irregularity occurrences observed by ROCSAT-1 (1st satellite of the Republic of China) during moderate to high solar activity years in two solstices are studied with respect to the vertical drift velocity and density variations. The post-midnight irregularity distributions are found to be similar to the well-documented pre-midnight ones, but are different from some published distributions taken during solar minimum years. Even though the post-midnight ionosphere is sinking in general, longitudes of frequent positive vertical drift and high density seems to coincide with the longitudes of high irregularity occurrences. Large scatters found in the vertical drift velocity and density around the dip equator in different ROCSAT-1 orbits indicate the existence of large and frequent variations in the vertical drift velocity and density that seem to be able to provide sufficient perturbations for the Rayleigh-Taylor (RT) instability to cause the irregularity occurrences. The need of seeding agents such as gravity waves from atmospheric convective clouds to initiate the Rayleigh-Taylor instability may not be necessary.

Experimental investigation and numerical simulations of void profile development in a vertical cylindrical pipe

International Nuclear Information System (INIS)

Grossetete, Claudie

1995-01-01

We present here an experimental investigation and some numerical simulations of void profile development in a vertical cylindrical pipe. This study is motivated by the lack of information dealing with the influence of entrance effects and bubble size evolution upon the multidimensional development of upward bubbly flow in pipe. The axial development of two-phase air-water upward bubbly and bubbly-to-slug transition flows in a vertical pipe is investigated experimentally first. Profiles of liquid mean velocity, liquid axial turbulent intensity, void fraction, bubble frequency, bubble velocity, mean equivalent bubble diameter and volumetric interfacial area are determined along the same test section at three axial locations. It is found that the bubbly-to-slug transition can be deduced from the simultaneous analysis of the different measured profiles. Local analysis of the studied bubbly flows shows that their development does not depend on the shape of the void distribution at the inlet. However, it is found that the bubble size evolution strongly affects the void distribution. Secondly, multidimensional numerical simulations of bubbly flows with very different gas injection modes are made with the help of the tri dimensional two-fluid ASTRID code. It is shown that the classical models used to close the transverse momentum equations of the two-fluid model (lift and dispersion forces) do not capture the physical phenomena of bubble migration in pipe flows. (author) [fr

Experimental investigation and numerical simulations of void profile development in a vertical cylindrical pipe

International Nuclear Information System (INIS)

Grossetete, C.

1995-12-01

We present here an experimental investigation and some numerical simulations of void profile development in a vertical cylindrical pipe. This study is motivated by the lack of information dealing with the influence of entrance effects and bubble size evolution upon the multidimensional development of upward bubbly flow in pipe. The axial development of two-phase air-water upward bubbly and bubbly-to-slug transition flows in a vertical pipe is investigated experimentally first. Profiles of liquid mean velocity, liquid axial turbulent intensity, void fraction, bubble frequency, bubble velocity, mean equivalent bubble diameter and volumetric interfacial area are determined along the same test section at three axial locations. It is found that the bubbly-to-slug transition can be deduced from the simultaneous analysis of the different measured profiles. Local analysis of the studied bubbly flows shows that their development does not depend on the shape of the void distribution at the inlet. However, it is found that the bubble size evolution strongly affects the void distribution. Secondly, multidimensional numerical simulations of bubbly flows with very different gas injection modes are made with the help of the tridimensional two-fluid ASTRID code. It is shown that the classical models used to close the transverse momentum equations of the two-fluid model (lift and dispersion forces) do not capture the physical phenomena of bubble migration in pipe flows

Estimating tropical vertical motion profile shapes from satellite observations

Science.gov (United States)

Back, L. E.; Handlos, Z.

2013-12-01

The vertical structure of tropical deep convection strongly influences interactions with larger scale circulations and climate. This research focuses on investigating this vertical structure and its relationship with mesoscale tropical weather states. We test the hypothesis that vertical motion shape varies in association with weather state type. We estimate mean state vertical motion profile shapes for six tropical weather states defined using cloud top pressure and optical depth properties from the International Satellite Cloud Climatology Project. The relationship between vertical motion and the dry static energy budget are utilized to set up a regression analysis that empirically determines two modes of variability in vertical motion from reanalysis data. We use these empirically determined modes, this relationship and surface convergence to estimate vertical motion profile shape from observations of satellite retrievals of rainfall and surface convergence. We find that vertical motion profile shapes vary systematically between different tropical weather states. The "isolated systems" regime exhibits a more ''bottom-heavy'' profile shape compared to the convective/thick cirrus and vigorous deep convective regimes, with maximum upward vertical motion occurring in the lower troposphere rather than the middle to upper troposphere. The variability we observe with our method does not coincide with that expected based on conventional ideas about how stratiform rain fraction and vertical motion are related.

Investigating Methods for Serving Visualizations of Vertical Profiles

Science.gov (United States)

Roberts, J. T.; Cechini, M. F.; Lanjewar, K.; Rodriguez, J.; Boller, R. A.; Baynes, K.

2017-12-01

Several geospatial web servers, web service standards, and mapping clients exist for the visualization of two-dimensional raster and vector-based Earth science data products. However, data products with a vertical component (i.e., vertical profiles) do not have the same mature set of technologies and pose a greater technical challenge when it comes to visualizations. There are a variety of tools and proposed standards, but no obvious solution that can handle the variety of visualizations found with vertical profiles. An effort is being led by members of the NASA Global Imagery Browse Services (GIBS) team to gather a list of technologies relevant to existing vertical profile data products and user stories. The goal is to find a subset of technologies, standards, and tools that can be used to build publicly accessible web services that can handle the greatest number of use cases for the widest audience possible. This presentation will describe results of the investigation and offer directions for moving forward with building a system that is capable of effectively and efficiently serving visualizations of vertical profiles.

Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities

Directory of Open Access Journals (Sweden)

L. Patara

2009-03-01

Full Text Available This paper analyzes the relationship between deep sedimentary fluxes and ocean current vertical velocities in an offshore area of the Ionian Sea, the deepest basin of the Eastern Mediterranean Sea. Sediment trap data are collected at 500 m and 2800 m depth in two successive moorings covering the period September 1999–May 2001. A tight coupling is observed between the upper and deep traps and the estimated particle sinking rates are more than 200 m day⁻¹. The current vertical velocity field is computed from a 1/16°×1/16° Ocean General Circulation Model simulation and from the wind stress curl. Current vertical velocities are larger and more variable than Ekman vertical velocities, yet the general patterns are alike. Current vertical velocities are generally smaller than 1 m day⁻¹: we therefore exclude a direct effect of downward velocities in determining high sedimentation rates. However we find that upward velocities in the subsurface layers of the water column are positively correlated with deep particle fluxes. We thus hypothesize that upwelling would produce an increase in upper ocean nutrient levels – thus stimulating primary production and grazing – a few weeks before an enhanced vertical flux is found in the sediment traps. High particle sedimentation rates may be attained by means of rapidly sinking fecal pellets produced by gelatinous macro-zooplankton. Other sedimentation mechanisms, such as dust deposition, are also considered in explaining large pulses of deep particle fluxes. The fast sinking rates estimated in this study might be an evidence of the efficiency of the biological pump in sequestering organic carbon from the surface layers of the deep Eastern Mediterranean basins.

Illumination Profile & Dispersion Variation Effects on Radial Velocity Measurements

Science.gov (United States)

Grieves, Nolan; Ge, Jian; Thomas, Neil B.; Ma, Bo; Li, Rui; SDSS-III

2015-01-01

The Multi-object APO Radial-Velocity Exoplanet Large-Area Survey (MARVELS) measures radial velocities using a fiber-fed dispersed fixed-delay interferometer (DFDI) with a moderate dispersion spectrograph. This setup allows a unique insight into the 2D illumination profile from the fiber on to the dispersion grating. Illumination profile investigations show large changes in the profile over time and fiber location. These profile changes are correlated with dispersion changes and long-term radial velocity offsets, a major problem within the MARVELS radial velocity data. Characterizing illumination profiles creates a method to both detect and correct radial velocity offsets, allowing for better planet detection. Here we report our early results from this study including improvement of radial velocity data points from detected giant planet candidates. We also report an illumination profile experiment conducted at the Kitt Peak National Observatory using the EXPERT instrument, which has a DFDI mode similar to MARVELS. Using profile controlling octagonal-shaped fibers, long term offsets over a 3 month time period were reduced from ~50 m/s to within the photon limit of ~4 m/s.

Measurement system of bubbly flow using ultrasonic velocity profile monitor and video data processing unit. 2. Flow characteristics of bubbly countercurrent flow

International Nuclear Information System (INIS)

Aritomi, Masanori; Zhou, Shirong; Nakajima, Makoto; Takeda, Yasushi; Mori, Michitsugu.

1997-01-01

The authors have developed a measurement system which is composed of an ultrasonic velocity profile monitor and a video data processing unit in order to clarify its multi-dimensional flow characteristics in bubbly flows and to offer a data base to validate numerical codes for multi-dimensional two-phase flow. In this paper, the measurement system was applied for bubbly countercurrent flows in a vertical rectangular channel. At first, both bubble and water velocity profiles and void fraction profiles in the channel were investigated statistically. Next, turbulence intensity in a continuous liquid phase was defined as a standard deviation of velocity fluctuation, and the two-phase multiplier profile of turbulence intensity in the channel was clarified as a ratio of the standard deviation of flow fluctuation in a bubbly countercurrent flow to that in a water single phase flow. Finally, the distribution parameter and drift velocity used in the drift flux model for bubbly countercurrent flows were calculated from the obtained velocity profiles of both phases and void fraction profile, and were compared with the correlation proposed for bubbly countercurrent flows. (author)

Vega-1 and Vega-2: vertical profiles of wind velocity according to Doppler measurements data at landing spacecrafts

International Nuclear Information System (INIS)

Kerzhanovich, V.V.; Antsibor, N.M.; Bakit'ko, R.V.

1987-01-01

Results of the measurements of the Venus atmosphere vertical motion using the ''Vega'' landing spacecrafts are presented. Signal emitted by the landing spacecraft transmitter was received by flying apparatus and retranslated to the Earth. The difference between the measured frequency of the retranslated signal and reference one (Doppler's shift) permitted to determine the velocity of the landing spacecraft with the accuracy of 2 cm/s with the pitch of 1 s

Vertical seismic profile data from well Mallik 2L-38 for gas hydrate studies

Energy Technology Data Exchange (ETDEWEB)

Mi, Y [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics; Walia, R [Victoria Univ., BC (Canada) School of Earth and Ocean Sciences; Hyndman, R [Geological Survey of Canada, Sidney, BC (Canada) Pacific Geoscience Centre

1999-07-01

A gas hydrate research well was drilled in the Canadian Arctic to study gas hydrates in a permafrost setting in a collaborative research project between the Japan National Oil Corp., the Geological Survey of Canada and other agencies. The multidisciplinary study included an electromagnetic survey, permafrost and gas hydrate coring, comprehensive downhole geophysical logging and measurement. Laboratory studies concerned studies on recovered cuttings and core including sedimentology, physical properties, geochemistry, and reservoir characteristics of the Mallik gas accumulation. As part of the Mallik 2L-38 field program, a vertical seismic profiling survey was conducted at zero and other offset source positions with three component receiver tools and horizontal and vertical vibration sources. A special effort was made to record shear wave data, which will be used to estimate the effect of gas hydrate on formation velocities and to determine gas hydrate concentration as a function of the Mallik gas accumulation. From the initial VSP analysis, certain conclusions follow: 1) zero offset vertical vibration component Z and horizontal X component data give reliable velocity determination within the gas hydrate formation zone. P wave velocities from offset VSP data show an excellent consistency with that from offset data and with the sonic log. And 2) the VSP data permit reliable identification of gas hydrate bearing zones. Abstract only included.

Velocity dispersion profiles of clusters of galaxies

International Nuclear Information System (INIS)

Struble, M.F.

1979-01-01

Velocity dispersion as a function of radius, called sigma/sub ls/ profiles, is presented for 13 clusters of galaxies having > or =30 radial velocities from both published and unpublished lists. A list of probable new members and possible outlying members for these clusters is also given. chi 2 and Kolmogoroff--Smirnoff one-sample tests for the goodness of fit of power laws to portions of the profiles indicate two significant structures in some profiles: (1) a local minimum corresponding to the local minimum noted in surface density or surface brightness profiles, and (2) a decrease in sigma/sub ls/ toward the cores. Both of these features are discussed in terms of a comparison with Wielen's N-body simulations. The sigma/sub ls/ profiles are placed in a new classification scheme which lends itself to interpreting clusters in a dynamical age sequence. The velocity field of galaxies at large distances from cluster centers is also discussed

Orographic precipitation and vertical velocity characteristics from drop size and fall velocity spectra observed by disdrometers

Science.gov (United States)

Lee, Dong-In; Kim, Dong-Kyun; Kim, Ji-Hyeon; Kang, Yunhee; Kim, Hyeonjoon

2017-04-01

During a summer monsoon season each year, severe weather phenomena caused by front, mesoscale convective systems, or typhoons often occur in the southern Korean Peninsula where is mostly comprised of complex high mountains. These areas play an important role in controlling formation, amount, and distribution of rainfall. As precipitation systems move over the mountains, they can develop rapidly and produce localized heavy rainfall. Thus observational analysis in the mountainous areas is required for studying terrain effects on the rapid rainfall development and its microphysics. We performed intensive field observations using two s-band operational weather radars around Mt. Jiri (1950 m ASL) during summertime on June and July in 2015-2016. Observation data of DSD (Drop Size Distribution) from Parsivel disdrometer and (w component) vertical velocity data from ultrasonic anemometers were analyzed for Typhoon Chanhom on 12 July 2015 and the heavy rain event on 1 July 2016. During the heavy rain event, a dual-Doppler radar analysis using Jindo radar and Gunsan radar was also conducted to examine 3-D wind fields and vertical structure of reflectivity in these areas. For examining up-/downdrafts in the windward or leeward side of Mt. Jiri, we developed a new scheme technique to estimate vertical velocities (w) from drop size and fall velocity spectra of Parsivel disdrometers at different stations. Their comparison with the w values observed by the 3D anemometer showed quite good agreement each other. The Z histogram with regard to the estimated w was similar to that with regard to R, indicating that Parsivel-estimated w is quite reasonable for classifying strong and weak rain, corresponding to updraft and downdraft, respectively. Mostly, positive w values (upward) were estimated in heavy rainfall at the windward side (D1 and D2). Negative w values (downward) were dominant even during large rainfall at the leeward side (D4). For D1 and D2, the upward w percentages were

Year-Long Vertical Velocity Statistics Derived from Doppler Lidar Data for the Continental Convective Boundary Layer

Energy Technology Data Exchange (ETDEWEB)

Berg, Larry K. [Pacific Northwest National Laboratory, Richland, Washington; Newsom, Rob K. [Pacific Northwest National Laboratory, Richland, Washington; Turner, David D. [Global Systems Division, NOAA/Earth System Research Laboratory, Boulder, Colorado

2017-09-01

One year of Coherent Doppler Lidar (CDL) data collected at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) site in Oklahoma is analyzed to provide profiles of vertical velocity variance, skewness, and kurtosis for cases of cloud-free convective boundary layers. The variance was scaled by the Deardorff convective velocity scale, which was successful when the boundary layer depth was stationary but failed in situations when the layer was changing rapidly. In this study the data are sorted according to time of day, season, wind direction, surface shear stress, degree of instability, and wind shear across the boundary-layer top. The normalized variance was found to have its peak value near a normalized height of 0.25. The magnitude of the variance changes with season, shear stress, and degree of instability, but was not impacted by wind shear across the boundary-layer top. The skewness was largest in the top half of the boundary layer (with the exception of wintertime conditions). The skewness was found to be a function of the season, shear stress, wind shear across the boundary-layer top, with larger amounts of shear leading to smaller values. Like skewness, the vertical profile of kurtosis followed a consistent pattern, with peak values near the boundary-layer top (also with the exception of wintertime data). The altitude of the peak values of kurtosis was found to be lower when there was a large amount of wind shear at the boundary-layer top.

A multi-offset vertical profiling (VSP) experiment for anisotropy analysis and imaging

Energy Technology Data Exchange (ETDEWEB)

Grech, G. K.; Lawton, D. [Calgary Univ., AB (Canada)

2000-09-01

Vertical seismic profiling (VSP) and surface seismic data are used to image and locate hydrocarbon targets in the subsurface, hence the importance of assessing which formations exhibit seismic velocity anisotropy and quantify their parameters for use during seismic imaging. The purpose of the experiments described in this paper was to determine whether the multiple dipping thin shale beds overlying the target area in the Rocky Mountain Foothills in southern Alberta exhibit seismic velocity anisotropy and if so, how this phenomenon affects the image of the underlying target. Traveltime inversion of the first arrival data from the multi-offset VSP in the study area has revealed that the Cretaceous shales exhibit velocity anisotropy of about 10 degrees. For a target depth of 3000 m and moderate dips of 30 to 50 degrees in the anisotropic overburden, it would be reasonable to expect a lateral shift in the imaged location of the target of up to 300 m in the up-direction of overlying bedding. 8 refs., 9 figs.

Vertical seismic profile data from well Mallik 2L-38 for gas hydrate studies

Energy Technology Data Exchange (ETDEWEB)

Mi, Y [Calgary Univ., AB (Canada); Walia, R [Victoria Univ., BC (Canada); Hyndman, R D; Sakai, A

1999-01-01

A gas hydrate research well was drilled in the Canadian Arctic to determine gas hydrates in a permafrost setting in a collaborative research project between the Japan National Oil Corp., and the Geological Survey of Canada with the participation of other agencies. The multidisciplinary study included an electromagnetic survey, permafrost and gas hydrate coring, and comprehensive downhole geophysical logging and measurement. Laboratory studies on recovered cores and cuttings included sedimentology, physical properties, geochemistry, and reservoir characteristics of the Mallik gas accumulation. As part of the field program, a vertical seismic profiling survey was conducted at zero and offset source positions with 3 component receiver tools and horizontal and vertical vibration sources. A special effort was made to record shear wave data, and results from this work were combined with down hole logs and regional surface seismic data. The data will be used also to determine the effect of gas hydrates on formation velocities and to measure gas hydrate concentrations as a function of depth in the formation penetrated by the well. Certain conclusions followed from the initial VSP analysis. 1) Zero offset vertical vibration Z component and horizontal X component data give reliable velocity estimation within the gas hydrate formation zone, and P wave velocities from offset data indicate excellent consistency with that from zero offset data and with the sonic log. 2) The VSP data permitted reliable identification of gas hydrate bearing zones. 4 refs.

Validity of a Simple Method for Measuring Force-Velocity-Power Profile in Countermovement Jump.

Science.gov (United States)

Jiménez-Reyes, Pedro; Samozino, Pierre; Pareja-Blanco, Fernando; Conceição, Filipe; Cuadrado-Peñafiel, Víctor; González-Badillo, Juan José; Morin, Jean-Benoît

2017-01-01

To analyze the reliability and validity of a simple computation method to evaluate force (F), velocity (v), and power (P) output during a countermovement jump (CMJ) suitable for use in field conditions and to verify the validity of this computation method to compute the CMJ force-velocity (F-v) profile (including unloaded and loaded jumps) in trained athletes. Sixteen high-level male sprinters and jumpers performed maximal CMJs under 6 different load conditions (0-87 kg). A force plate sampling at 1000 Hz was used to record vertical ground-reaction force and derive vertical-displacement data during CMJ trials. For each condition, mean F, v, and P of the push-off phase were determined from both force-plate data (reference method) and simple computation measures based on body mass, jump height (from flight time), and push-off distance and used to establish the linear F-v relationship for each individual. Mean absolute bias values were 0.9% (± 1.6%), 4.7% (± 6.2%), 3.7% (± 4.8%), and 5% (± 6.8%) for F, v, P, and slope of the F-v relationship (S Fv ), respectively. Both methods showed high correlations for F-v-profile-related variables (r = .985-.991). Finally, all variables computed from the simple method showed high reliability, with ICC >.980 and CV push-off distance, and jump height are known.

Bias in mean velocities and noise in variances and covariances measured using a multistatic acoustic profiler: the Nortek Vectrino Profiler

Science.gov (United States)

Thomas, R. E.; Schindfessel, L.; McLelland, S. J.; Creëlle, S.; De Mulder, T.

2017-07-01

This paper compiles the technical characteristics and operating principles of the Nortek Vectrino Profiler and reviews previously reported user experiences. A series of experiments are then presented that investigate instrument behaviour and performance, with a particular focus on variations within the profile. First, controlled tests investigate the sensitivity of acoustic amplitude (and Signal-to-Noise Ratio, SNR) and pulse-to-pulse correlation coefficient, R 2, to seeding concentration and cell geometry. Second, a novel methodology that systematically shifts profiling cells through a single absolute vertical position investigates the sensitivity of mean velocities, SNR and noise to: (a) emitted sound intensity and the presence (or absence) of acoustic seeding; and (b) varying flow rates under ideal acoustic seeding conditions. A new solution is derived to quantify the noise affecting the two perpendicular tristatic systems of the Vectrino Profiler and its contribution to components of the Reynolds stress tensor. Results suggest that for the Vectrino Profiler: 1. optimum acoustic seeding concentrations are ~3000 to 6000 mg L-1 2. mean velocity magnitudes are biased by variable amounts in proximal cells but are consistently underestimated in distal cells; 3. noise varies parabolically with a minimum around the ‘sweet spot’, 50 mm below the transceiver; 4. the receiver beams only intersect at the sweet spot and diverge nearer to and further from the transceiver. This divergence significantly reduces the size of the sampled area away from the sweet spot, reducing data quality; 5. the most reliable velocity data will normally be collected in the region between approximately 43 and 61 mm below the transceiver.

Bias in mean velocities and noise in variances and covariances measured using a multistatic acoustic profiler: the Nortek Vectrino Profiler

International Nuclear Information System (INIS)

Thomas, R E; Schindfessel, L; Creëlle, S; De Mulder, T; McLelland, S J

2017-01-01

This paper compiles the technical characteristics and operating principles of the Nortek Vectrino Profiler and reviews previously reported user experiences. A series of experiments are then presented that investigate instrument behaviour and performance, with a particular focus on variations within the profile. First, controlled tests investigate the sensitivity of acoustic amplitude (and Signal-to-Noise Ratio, SNR) and pulse-to-pulse correlation coefficient, R 2 , to seeding concentration and cell geometry. Second, a novel methodology that systematically shifts profiling cells through a single absolute vertical position investigates the sensitivity of mean velocities, SNR and noise to: (a) emitted sound intensity and the presence (or absence) of acoustic seeding; and (b) varying flow rates under ideal acoustic seeding conditions. A new solution is derived to quantify the noise affecting the two perpendicular tristatic systems of the Vectrino Profiler and its contribution to components of the Reynolds stress tensor. Results suggest that for the Vectrino Profiler: 1. optimum acoustic seeding concentrations are ∼3000 to 6000 mg L −1 ; 2. mean velocity magnitudes are biased by variable amounts in proximal cells but are consistently underestimated in distal cells; 3. noise varies parabolically with a minimum around the ‘sweet spot’, 50 mm below the transceiver; 4. the receiver beams only intersect at the sweet spot and diverge nearer to and further from the transceiver. This divergence significantly reduces the size of the sampled area away from the sweet spot, reducing data quality; 5. the most reliable velocity data will normally be collected in the region between approximately 43 and 61 mm below the transceiver. (paper)

Measurement system of bubbly flow using Ultrasonic Velocity Profile Monitor and Video Data Processing Unit. 3. Comparison of flow characteristics between bubbly cocurrent and countercurrent flows

International Nuclear Information System (INIS)

Zhou, Shirong; Suzuki, Yumiko; Aritomi, Masanori; Matsuzaki, Mitsuo; Takeda, Yasushi; Mori, Michitsugu

1998-01-01

The authors have developed a new measurement system which consisted of an Ultrasonic Velocity Profile Monitor (UVP) and a Video Data Processing Unit (VDP) in order to clarify the two-dimensional flow characteristics in bubbly flows and to offer a data base to validate numerical codes for two-dimensional two-phase flow. In the present paper, the proposed measurement system is applied to fully developed bubbly cocurrent flows in a vertical rectangular channel. At first, both bubble and water velocity profiles and void fraction profiles in the channel were investigated statistically. In addition, the two-phase multiplier profile of turbulence intensity, which was defined as a ratio of the standard deviation of velocity fluctuation in a bubbly flow to that in a water single phase flow, were examined. Next, these flow characteristics were compared with those in bubbly countercurrent flows reported in our previous paper. Finally, concerning the drift flux model, the distribution parameter and drift velocity were obtained directly from both bubble and water velocity profiles and void fraction profiles, and their results were compared with those in bubbly countercurrent flows. (author)

Evaluation of vertical profiles to design continuous descent approach procedure

Science.gov (United States)

Pradeep, Priyank

The current research focuses on predictability, variability and operational feasibility aspect of Continuous Descent Approach (CDA), which is among the key concepts of the Next Generation Air Transportation System (NextGen). The idle-thrust CDA is a fuel economical, noise and emission abatement procedure, but requires increased separation to accommodate for variability and uncertainties in vertical and speed profiles of arriving aircraft. Although a considerable amount of researches have been devoted to the estimation of potential benefits of the CDA, only few have attempted to explain the predictability, variability and operational feasibility aspect of CDA. The analytical equations derived using flight dynamics and Base of Aircraft and Data (BADA) Total Energy Model (TEM) in this research gives insight into dependency of vertical profile of CDA on various factors like wind speed and gradient, weight, aircraft type and configuration, thrust settings, atmospheric factors (deviation from ISA (DISA), pressure and density of the air) and descent speed profile. Application of the derived equations to idle-thrust CDA gives an insight into sensitivity of its vertical profile to multiple factors. This suggests fixed geometric flight path angle (FPA) CDA has higher degree of predictability and lesser variability at the cost of non-idle and low thrust engine settings. However, with optimized design this impact can be overall minimized. The CDA simulations were performed using Future ATM Concept Evaluation Tool (FACET) based on radar-track and aircraft type data (BADA) of the real air-traffic to some of the busiest airports in the USA (ATL, SFO and New York Metroplex (JFK, EWR and LGA)). The statistical analysis of the vertical profiles of CDA shows 1) mean geometric FPAs derived from various simulated vertical profiles are consistently shallower than 3° glideslope angle and 2) high level of variability in vertical profiles of idle-thrust CDA even in absence of

Measurement of LBE flow velocity profile by UDVP

International Nuclear Information System (INIS)

Kikuchi, Kenji; Takeda, Yasushi; Obayashi, Hiroo; Tezuka, Masao; Sato, Hiroshi

2006-01-01

Measurements of liquid metal lead-bismuth eutectic (LBE), flow velocity profile were realized in the spallation neutron source target model by the ultrasonic Doppler velocity profiler (UVDP) technique. So far, it has not been done well, because both of poor wetting property of LBE with stainless steels and poor performance of supersonic probes at high temperatures. The measurement was made for a return flow in the target model, which has coaxially arranged annular and tube channels, in the JAEA Lead Bismuth Loop-2 (JLBL-2). The surface treatment of LBE container was examined. It was found that the solder coating was effective to enhance an intensity of reflected ultrasonic wave. This treatment has been applied to the LBE loop, which was operated up to 150 deg. C. The electro magnetic pump generates LBE flow and the flow rate was measured by the electro magnetic flow meter. By changing the flow rate of LBE, velocity profiles in the target were measured. It was confirmed that the maximum velocity in the time-averaged velocity distribution on the target axis was proportional to the flow rate measured by the electro magnetic flow meter

Periodic Variations in the Vertical Velocities of Galactic Masers

Directory of Open Access Journals (Sweden)

Bobylev V. V.

2016-03-01

Full Text Available We compiled published data on Galactic masers with VLBI-measured trigonometric parallaxes and determined the residual tangential, ∆Vcirc, and radial, ∆VR, velocities for 120 masers. We used these data to redetermine the parameters of the Galactic spiral density wave using the method of spectral analysis. The most interesting result of this study is the detection of wavelike oscillations of vertical spatial velocities (W versus distance R from the Galactic rotation axis. Spectral analysis allowed us to determine the perturbation wavelength and the amplitude of this wave, which we found to be equal to λW = 3.4 ± 0.7 kpc and fW = 4.9 ± 1.2 km s−1, respectively.

Horizontal and Vertical Velocities Derived from the IDS Contribution to ITRF2014, and Comparisons with Geophysical Models

Science.gov (United States)

Moreaux, G.; Lemoine, F. G.; Argus, D. F.; Santamaria-Gomez, A.; Willis, P.; Soudarin, L.; Gravelle, M.; Ferrage, P.

2016-01-01

In the context of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the IDS Combination Center estimated a cumulative DORIS position and velocity solution to obtain mean horizontal and vertical motion of 160 stations at 71 DORIS sites. The main objective of this study is to validate the velocities of the DORIS sites by comparison with external models or time series. Horizontal velocities are compared with two recent global plate models (GEODVEL 2010 and NNR-MORVEL56). Prior to the comparisons, DORIS horizontal velocities were corrected for Global Isostatic Adjustment (GIA) from the ICE-6G (VM5a) model. For more than half of the sites, the DORIS horizontal velocities differ from the global plate models by less than 2-3 mm/yr. For five of the sites (Arequipa, Dionysos/Gavdos, Manila, Santiago) with horizontal velocity differences wrt these models larger than 10 mm/yr, comparisons with GNSS estimates show the veracity of the DORIS motions. Vertical motions from the DORIS cumulative solution are compared with the vertical velocities derived from the latest GPS cumulative solution over the time span 1995.0-2014.0 from the University of La Rochelle (ULR6) solution at 31 co-located DORIS-GPS sites. These two sets of vertical velocities show a correlation coefficient of 0.83. Vertical differences are larger than 2 mm/yr at 23 percent of the sites. At Thule the disagreement is explained by fine-tuned DORIS discontinuities in line with the mass variations of outlet glaciers. Furthermore, the time evolution of the vertical time series from the DORIS station in Thule show similar trends to the GRACE equivalent water height.

Horizontal and vertical velocities derived from the IDS contribution to ITRF2014, and comparisons with geophysical models

Science.gov (United States)

Moreaux, G.; Lemoine, F. G.; Argus, D. F.; Santamaría-Gómez, A.; Willis, P.; Soudarin, L.; Gravelle, M.; Ferrage, P.

2016-10-01

In the context of the 2014 realization of the International Terrestrial Reference Frame, the International DORIS (Doppler Orbitography Radiopositioning Integrated by Satellite) Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the IDS combination centre estimated a cumulative DORIS position and velocity solution to obtain mean horizontal and vertical motion of 160 stations at 71 DORIS sites. The main objective of this study is to validate the velocities of the DORIS sites by comparison with external models or time-series. Horizontal velocities are compared with two recent global plate models (GEODVEL 2010 and NNR-MORVEL56). Prior to the comparisons, DORIS horizontal velocities were corrected for Global Isostatic Adjustment from the ICE-6G (VM5a) model. For more than half of the sites, the DORIS horizontal velocities differ from the global plate models by less than 2-3 mm yr-1. For five of the sites (Arequipa, Dionysos/Gavdos, Manila and Santiago) with horizontal velocity differences with respect to these models larger than 10 mm yr-1, comparisons with GNSS estimates show the veracity of the DORIS motions. Vertical motions from the DORIS cumulative solution are compared with the vertical velocities derived from the latest GPS cumulative solution over the time span 1995.0-2014.0 from the University of La Rochelle solution at 31 co-located DORIS-GPS sites. These two sets of vertical velocities show a correlation coefficient of 0.83. Vertical differences are larger than 2 mm yr-1 at 23 percent of the sites. At Thule, the disagreement is explained by fine-tuned DORIS discontinuities in line with the mass variations of outlet glaciers. Furthermore, the time evolution of the vertical time-series from the DORIS station in Thule show similar trends to the GRACE equivalent water height.

Transition of unsteady velocity profiles with reverse flow

Science.gov (United States)

Das, Debopam; Arakeri, Jaywant H.

1998-11-01

This paper deals with the stability and transition to turbulence of wall-bounded unsteady velocity profiles with reverse flow. Such flows occur, for example, during unsteady boundary layer separation and in oscillating pipe flow. The main focus is on results from experiments in time-developing flow in a long pipe, which is decelerated rapidly. The flow is generated by the controlled motion of a piston. We obtain analytical solutions for laminar flow in the pipe and in a two-dimensional channel for arbitrary piston motions. By changing the piston speed and the length of piston travel we cover a range of values of Reynolds number and boundary layer thickness. The velocity profiles during the decay of the flow are unsteady with reverse flow near the wall, and are highly unstable due to their inflectional nature. In the pipe, we observe from flow visualization that the flow becomes unstable with the formation of what appears to be a helical vortex. The wavelength of the instability [simeq R: similar, equals]3[delta] where [delta] is the average boundary layer thickness, the average being taken over the time the flow is unstable. The time of formation of the vortices scales with the average convective time scale and is [simeq R: similar, equals]39/([Delta]u/[delta]), where [Delta]u=(umax[minus sign]umin) and umax, umin and [delta] are the maximum velocity, minimum velocity and boundary layer thickness respectively at each instant of time. The time to transition to turbulence is [simeq R: similar, equals]33/([Delta]u/[delta]). Quasi-steady linear stability analysis of the velocity profiles brings out two important results. First that the stability characteristics of velocity profiles with reverse flow near the wall collapse when scaled with the above variables. Second that the wavenumber corresponding to maximum growth does not change much during the instability even though the velocity profile does change substantially. Using the results from the experiments and the

Observations of the vertical structure of turbulent oscillatory boundary layers above fixed roughness beds using a prototype wideband coherent Doppler profiler: 1. The oscillatory component of the flow

Science.gov (United States)

Hay, Alex E.; Zedel, Len; Cheel, Richard; Dillon, Jeremy

2012-03-01

Results are presented from an experimental investigation of rough turbulent oscillatory boundary layers using a prototype wideband bistatic coherent Doppler profiler. The profiler operates in the 1.2 MHz to 2.3 MHz frequency band and uses software-defined radio technologies for digital control of the frequency content and shape of the transmit pulse and for digital complex demodulation of the received signals. Velocity profiles are obtained at sub-millimeter range resolution and 100 Hz profiling rates (each profile being an ensemble average of 10 pulse pairs). The measurements were carried out above beds of fixed sand or gravel particles, with median grain diameters of 0.37 mm and 3.9 mm, respectively, oscillating sinusoidally at a 10 s period through excursions of 0.75 m to 1.5 m. The resulting vertical profiles of horizontal velocity magnitude and phase, with the vertical axis scaled by ℓ = κu∗m/ω, are comparable to similarly scaled profiles obtained using laser Doppler anemometry by Sleath (1987) and Jensen (1988). A key objective of the comparisons between the previous experiments and those reported here was to establish how close to the bed reliable velocity measurements can be made with the sonar. This minimum distance above the bed is estimated to be 5 ± 1 mm, a value approaching the 3 to 4 mm limit set by the path of least time.

Characteristics of vertical velocity in marine stratocumulus: comparison of large eddy simulations with observations

International Nuclear Information System (INIS)

Guo Huan; Liu Yangang; Daum, Peter H; Senum, Gunnar I; Tao, W-K

2008-01-01

We simulated a marine stratus deck sampled during the Marine Stratus/Stratocumulus Experiment (MASE) with a three-dimensional large eddy simulation (LES) model at different model resolutions. Various characteristics of the vertical velocity from the model simulations were evaluated against those derived from the corresponding aircraft in situ observations, focusing on standard deviation, skewness, kurtosis, probability density function (PDF), power spectrum, and structure function. Our results show that although the LES model captures reasonably well the lower-order moments (e.g., horizontal averages and standard deviations), it fails to simulate many aspects of the higher-order moments, such as kurtosis, especially near cloud base and cloud top. Further investigations of the PDFs, power spectra, and structure functions reveal that compared to the observations, the model generally underestimates relatively strong variations on small scales. The results also suggest that increasing the model resolutions improves the agreements between the model results and the observations in virtually all of the properties that we examined. Furthermore, the results indicate that a vertical grid size <10 m is necessary for accurately simulating even the standard-deviation profile, posing new challenges to computer resources.

An analytical model for displacement velocity of liquid film on a hot vertical surface

International Nuclear Information System (INIS)

Yoshioka, Keisuke; Hasegawa, Shu

1975-01-01

The downward progress of the advancing front of a liquid film streaming down a heated vertical surface, as it would occur in emergency core cooling, is much slower than in the case of ordinary streaming down along a heated surface already wetted with the liquid. A two-dimensional heat conduction model is developed for evaluating this velocity of the liquid front, which takes account of the heat removal by ordinary flow boiling mechanism. In the analysis, the maximum heat flux and the calefaction temperature are taken up as parameters in addition to the initial dry heated wall temperature, the flow rate and the velocity of downward progress of the liquid front. The temperature profile is calculated for various combinations of these parameters. Two criteria are proposed for choosing the most suitable combination of the parameters. One is to reject solutions that represent an oscillating wall temperature distribution, and the second criterion requires that the length of the zone of violent boiling immediately following the liquid front should not be longer than about 1 mm, this value being determined from comparisons made between experiment and calculation. Application of the above two criteria resulted in reasonable values obtained for the calefaction temperature and the maximum heat flux, and the velocity of the liquid front derived therefrom showed good agreement with experiment. (auth.)

Time changes of vertical profile of neutron fluence rate in LVR-15 reactor

International Nuclear Information System (INIS)

Viererbl, L.; Stehno, J.; Erben, O.; Lahodova, Z.; Marek, M.

2003-01-01

The LVR-15 reactor is a light water research type reactor, which is situated, in Nuclear Research Institute, Rez near Prague. The reactor is used as a multipurpose facility. For some experiments and material productions, e.g. for homogeneity of silicon resistance in production of radiation doped silicon, the time changes of vertical profile of neutron fluence rate are particularly important. The assembly used for silicon irradiation has two self-powered neutron detectors installed in a vertical irradiation channel in LVR-15 reactor. Vertical profile of thermal neutron fluence rate was automatically scanned during reactor operation. The results of measurements made in 2002 and 2003 with these detectors are presented. A set of vertical profile measurements was made during two 21-days reactor cycles. During the cycle the vertical profile slightly changes both in the position of its maximum and in the shape. The time dependences of the position of profile maximum and the profile width at half maximum during the cycle are given. (author)

Effect of flow velocity on the process of air-steam condensation in a vertical tube condenser

Science.gov (United States)

Havlík, Jan; Dlouhý, Tomáš

2018-06-01

This article describes the influence of flow velocity on the condensation process in a vertical tube. For the case of condensation in a vertical tube condenser, both the pure steam condensation process and the air-steam mixture condensation process were theoretically and experimentally analyzed. The influence of steam flow velocity on the value of the heat transfer coefficient during the condensation process was evaluated. For the condensation of pure steam, the influence of flow velocity on the value of the heat transfer coefficient begins to be seen at higher speeds, conversely, this effect is negligible at low values of steam velocity. On the other hand, for the air-steam mixture condensation, the influence of flow velocity must always be taken into account. The flow velocity affects the water vapor diffusion process through non-condensing air. The presence of air significantly reduces the value of the heat transfer coefficient. This drop in the heat transfer coefficient is significant at low velocities; on the contrary, the decrease is relatively small at high values of the velocity.

Estimates of vertical velocities and eddy coefficients in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Varkey, M.J.; Sastry, J.S.

Vertical velocities and eddy coefficients in the intermediate depths of the Bay of Bengal are calculated from mean hydrographic data for 300 miles-squares. The linear current density (sigma- O) versus log-depth plots show steady balance between...

Vertical profiles of BC direct radiative effect over Italy: high vertical resolution data and atmospheric feedbacks

Science.gov (United States)

Močnik, Griša; Ferrero, Luca; Castelli, Mariapina; Ferrini, Barbara S.; Moscatelli, Marco; Grazia Perrone, Maria; Sangiorgi, Giorgia; Rovelli, Grazia; D'Angelo, Luca; Moroni, Beatrice; Scardazza, Francesco; Bolzacchini, Ezio; Petitta, Marcello; Cappelletti, David

2016-04-01

Black carbon (BC), and its vertical distribution, affects the climate. Global measurements of BC vertical profiles are lacking to support climate change research. To fill this gap, a campaign was conducted over three Italian basin valleys, Terni Valley (Appennines), Po Valley and Passiria Valley (Alps), to characterize the impact of BC on the radiative budget under similar orographic conditions. 120 vertical profiles were measured in winter 2010. The BC vertical profiles, together with aerosol size distribution, aerosol chemistry and meteorological parameters, have been determined using a tethered balloon-based platform equipped with: a micro-Aethalometer AE51 (Magee Scientific), a 1.107 Grimm OPC (0.25-32 μm, 31 size classes), a cascade impactor (Siuotas SKC), and a meteorological station (LSI-Lastem). The aerosol chemical composition was determined from collected PM2.5 samples. The aerosol absorption along the vertical profiles was measured and optical properties calculated using the Mie theory applied to the aerosol size distribution. The aerosol optical properties were validated with AERONET data and then used as inputs to the radiative transfer model libRadtran. Vertical profiles of the aerosol direct radiative effect, the related atmospheric absorption and the heating rate were calculated. Vertical profile measurements revealed some common behaviors over the studied basin valleys. From below the mixing height to above it, a marked concentration drop was found for both BC (from -48.4±5.3% up to -69.1±5.5%) and aerosol number concentration (from -23.9±4.3% up to -46.5±7.3%). These features reflected on the optical properties of the aerosol. Absorption and scattering coefficients decreased from below the MH to above it (babs from -47.6±2.5% up to -71.3±3.0% and bsca from -23.5±0.8% up to -61.2±3.1%, respectively). Consequently, the Single Scattering Albedo increased above the MH (from +4.9±2.2% to +7.4±1.0%). The highest aerosol absorption was

Inference and Biogeochemical Response of Vertical Velocities inside a Mode Water Eddy

Science.gov (United States)

Barceló-Llull, B.; Pallas Sanz, E.; Sangrà, P.

2016-02-01

With the aim to study the modulation of the biogeochemical fluxes by the ageostrophic secondary circulation in anticyclonic mesoscale eddies, a typical eddy of the Canary Eddy Corridor was interdisciplinary surveyed on September 2014 in the framework of the PUMP project. The eddy was elliptical shaped, 4 month old, 110 km diameter and 400 m depth. It was an intrathermocline type often also referred as mode water eddy type. We inferred the mesoscale vertical velocity field resolving a generalized omega equation from the 3D density and ADCP velocity fields of a five-day sampled CTD-SeaSoar regular grid centred on the eddy. The grid transects where 10 nautical miles apart. Although complex, in average, the inferred omega velocity field (hereafter w) shows a dipolar structure with downwelling velocities upstream of the propagation path (west) and upwelling velocities downstream. The w at the eddy center was zero and maximum values were located at the periphery attaining ca. 6 m day-1. Coinciding with the occurrence of the vertical velocities cells a noticeable enhancement of phytoplankton biomass was observed at the eddy periphery respect to the far field. A corresponding upward diapycnal flux of nutrients was also observed at the periphery. As minimum velocities where reached at the eddy center, lineal Ekman pumping mechanism was discarded. Minimum values of phytoplankton biomass where also observed at the eddy center. The possible mechanisms for such dipolar w cell are still being investigated, but an analysis of the generalized omega equation forcing terms suggest that it may be a combination of horizontal deformation and advection of vorticity by the ageostrophic current (related to nonlinear Ekman pumping). As expected for Trades, the wind was rather constant and uniform with a speed of ca. 5 m s-1. Diagnosed nonlinear Ekman pumping leaded also to a dipolar cell that mirrors the omega w dipolar cell.

In situ profiling of eastern Arabian Sea coastal waters using a new autonomous vertical profiler

Digital Repository Service at National Institute of Oceanography (India)

Desa, E.S.; Madhan, R.; Dabholkar, N.A.; Prabhudesai, S.P.; Navelkar, G.S.; Mascarenhas, A.A.M.Q.; Afzulpurkar, S.; Phaldesai, M.; Maurya, P.

The autonomous vertical profiler (AVP) presented here offers a fast, cost-effective, optimized approach to profiling in coastal waters. It consists of a hands-free, slightly buoyant, motor-driven in situ robot profiler that requires no operator...

A GIS-based Computational Tool for Multidimensional Flow Velocity by Acoustic Doppler Current Profilers

International Nuclear Information System (INIS)

Kim, D; Winkler, M; Muste, M

2015-01-01

Acoustic Doppler Current Profilers (ADCPs) provide efficient and reliable flow measurements compared to other tools for characteristics of the riverine environments. In addition to originally targeted discharge measurements, ADCPs are increasingly utilized to assess river flow characteristics. The newly developed VMS (Velocity Mapping Software) aims at providing an efficient process for quality assurance, mapping velocity vectors for visualization and facilitating comparison with physical and numerical model results. VMS was designed to provide efficient and smooth work flows for processing groups of transects. The software allows the user to select group of files and subsequently to conduct statistical and graphical quality assurance on the files as a group or individually as appropriate. VMS also enables spatial averaging in horizontal and vertical plane for ADCP data in a single or multiple transects over the same or consecutive cross sections. The analysis results are displayed in numerical and graphical formats. (paper)

Simulation-Based Optimization of a Vector Showerhead System for the Control of Flow Field Profile in a Vertical Reactor Chamber

Directory of Open Access Journals (Sweden)

Huanxiong Xia

2014-03-01

Full Text Available Optimization of a vector showerhead in a vertical reactor involves thousands of holes on the showerhead face plate and the spatial distribution of physical fields, so parameterizing the geometry configuration of the holes in high resolution is very difficult, which makes the conventional optimization methods hard to deal with. To solve this problem, a profile error feedback (PEF optimization solution was proposed to optimize a vector showerhead gas delivery system for the control of mass transport. The gas velocity profile in the reactor and the continuous-feature impedance distribution profile on the showerhead face plate are defined as design objective and variables, respectively. A cyclic iterative approximation idea was implemented in this solution. The algorithm was started from a guessed initial design model and then cyclically adjusted the design variables by the constructed PEF iterative formula to generate a better model and to make the gas velocity profile in the critical domain of the new model continually approximate to the expected profile, until it could be accepted. Finally, the optimized impedance profile was mapped to the holes geometry configuration through the established equivalent impedance model for the showerhead face plate.

Proposed method for reconstructing velocity profiles using a multi-electrode electromagnetic flow meter

International Nuclear Information System (INIS)

Kollár, László E; Lucas, Gary P; Zhang, Zhichao

2014-01-01

An analytical method is developed for the reconstruction of velocity profiles using measured potential distributions obtained around the boundary of a multi-electrode electromagnetic flow meter (EMFM). The method is based on the discrete Fourier transform (DFT), and is implemented in Matlab. The method assumes the velocity profile in a section of a pipe as a superposition of polynomials up to sixth order. Each polynomial component is defined along a specific direction in the plane of the pipe section. For a potential distribution obtained in a uniform magnetic field, this direction is not unique for quadratic and higher-order components; thus, multiple possible solutions exist for the reconstructed velocity profile. A procedure for choosing the optimum velocity profile is proposed. It is applicable for single-phase or two-phase flows, and requires measurement of the potential distribution in a non-uniform magnetic field. The potential distribution in this non-uniform magnetic field is also calculated for the possible solutions using weight values. Then, the velocity profile with the calculated potential distribution which is closest to the measured one provides the optimum solution. The reliability of the method is first demonstrated by reconstructing an artificial velocity profile defined by polynomial functions. Next, velocity profiles in different two-phase flows, based on results from the literature, are used to define the input velocity fields. In all cases, COMSOL Multiphysics is used to model the physical specifications of the EMFM and to simulate the measurements; thus, COMSOL simulations produce the potential distributions on the internal circumference of the flow pipe. These potential distributions serve as inputs for the analytical method. The reconstructed velocity profiles show satisfactory agreement with the input velocity profiles. The method described in this paper is most suitable for stratified flows and is not applicable to axisymmetric flows in

Inferring regional vertical crustal velocities from averaged relative sea level trends: A proof of concept

Directory of Open Access Journals (Sweden)

Bâki Iz H.

2017-02-01

Full Text Available This study demonstrates that relative sea level trends calculated from long-term tide gauge records can be used to estimate relative vertical crustal velocities in a region with high accuracy. A comparison of the weighted averages of the relative sea level trends estimated at six tide gauge stations in two clusters along the Eastern coast of United States, in Florida and in Maryland, reveals a statistically significant regional vertical crustal motion of Maryland with respect to Florida with a subsidence rate of −1.15±0.15 mm/yr identified predominantly due to the ongoing glacial isostatic adjustment process. The estimate is a consilience value to validate vertical crustal velocities calculated from GPS time series as well as towards constraining predictive GIA models in these regions.

High-resolution vertical velocities and their power spectrum observed with the MAARSY radar - Part 1: frequency spectrum

Science.gov (United States)

Li, Qiang; Rapp, Markus; Stober, Gunter; Latteck, Ralph

2018-04-01

The Middle Atmosphere Alomar Radar System (MAARSY) installed at the island of Andøya has been run for continuous probing of atmospheric winds in the upper troposphere and lower stratosphere (UTLS) region. In the current study, we present high-resolution wind measurements during the period between 2010 and 2013 with MAARSY. The spectral analysis applying the Lomb-Scargle periodogram method has been carried out to determine the frequency spectra of vertical wind velocity. From a total of 522 days of observations, the statistics of the spectral slope have been derived and show a dependence on the background wind conditions. It is a general feature that the observed spectra of vertical velocity during active periods (with wind velocity > 10 m s-1) are much steeper than during quiet periods (with wind velocity wind conditions considered together the general spectra are obtained and their slopes are compared with the background horizontal winds. The comparisons show that the observed spectra become steeper with increasing wind velocities under quiet conditions, approach a spectral slope of -5/3 at a wind velocity of 10 m s-1 and then roughly maintain this slope (-5/3) for even stronger winds. Our findings show an overall agreement with previous studies; furthermore, they provide a more complete climatology of frequency spectra of vertical wind velocities under different wind conditions.

Determination of vertical velocities in the equatorial part of the western Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Bahulayan, N.; Varadachari, V.V.R.

Using steady state two-dimensional turbulent diffusion equations of salt and heat some important characteristics of vertical circulation in the equatorial part of the Indian Ocean have been evaluated and discussed. Upwelling and sinking velocities...

Ultrasonic velocity profiling rheometry based on a widened circular Couette flow

International Nuclear Information System (INIS)

Shiratori, Takahisa; Tasaka, Yuji; Oishi, Yoshihiko; Murai, Yuichi

2015-01-01

We propose a new rheometry for characterizing the rheological properties of fluids. The technique produces flow curves, which represent the relationship between the fluid shear rate and shear stress. Flow curves are obtained by measuring the circumferential velocity distribution of tested fluids in a circular Couette system, using an ultrasonic velocity profiling technique. By adopting a widened gap of concentric cylinders, a designed range of the shear rate is obtained so that velocity profile measurement along a single line directly acquires flow curves. To reduce the effect of ultrasonic noise on resultant flow curves, several fitting functions and variable transforms are examined to best approximate the velocity profile without introducing a priori rheological models. Silicone oil, polyacrylamide solution, and yogurt were used to evaluate the applicability of this technique. These substances are purposely targeted as examples of Newtonian fluids, shear thinning fluids, and opaque fluids with unknown rheological properties, respectively. We find that fourth-order Chebyshev polynomials provide the most accurate representation of flow curves in the context of model-free rheometry enabled by ultrasonic velocity profiling. (paper)

A measurement system for vertical seawater profiles close to the air-sea interface

Science.gov (United States)

Sims, Richard P.; Schuster, Ute; Watson, Andrew J.; Yang, Ming Xi; Hopkins, Frances E.; Stephens, John; Bell, Thomas G.

2017-09-01

This paper describes a near-surface ocean profiler, which has been designed to precisely measure vertical gradients in the top 10 m of the ocean. Variations in the depth of seawater collection are minimized when using the profiler compared to conventional CTD/rosette deployments. The profiler consists of a remotely operated winch mounted on a tethered yet free-floating buoy, which is used to raise and lower a small frame housing sensors and inlet tubing. Seawater at the inlet depth is pumped back to the ship for analysis. The profiler can be used to make continuous vertical profiles or to target a series of discrete depths. The profiler has been successfully deployed during wind speeds up to 10 m s-1 and significant wave heights up to 2 m. We demonstrate the potential of the profiler by presenting measured vertical profiles of the trace gases carbon dioxide and dimethylsulfide. Trace gas measurements use an efficient microporous membrane equilibrator to minimize the system response time. The example profiles show vertical gradients in the upper 5 m for temperature, carbon dioxide and dimethylsulfide of 0.15 °C, 4 µatm and 0.4 nM respectively.

How Informative are the Vertical Buoyancy and the Prone Gliding Tests to Assess Young Swimmers’ Hydrostatic and Hydrodynamic Profiles?

Science.gov (United States)

Barbosa, Tiago M.; Costa, Mário J.; Morais, Jorge E; Moreira, Marc; Silva, António J.; Marinho, Daniel A.

2012-01-01

The aim of this research was to develop a path-flow analysis model to highlight the relationships between buoyancy and prone gliding tests and some selected anthropometrical and biomechanical variables. Thirty-eight young male swimmers (12.97 ± 1.05 years old) with several competitive levels were evaluated. It were assessed the body mass, height, fat mass, body surface area, vertical buoyancy, prone gliding after wall push-off, stroke length, stroke frequency and velocity after a maximal 25 [m] swim. The confirmatory model included the body mass, height, fat mass, prone gliding test, stroke length, stroke frequency and velocity. All theoretical paths were verified except for the vertical buoyancy test that did not present any relationship with anthropometrical and biomechanical variables nor with the prone gliding test. The good-of-fit from the confirmatory path-flow model, assessed with the standardized root mean square residuals (SRMR), is considered as being close to the cut-off value, but even so not suitable of the theory (SRMR = 0.11). As a conclusion, vertical buoyancy and prone gliding tests are not the best techniques to assess the swimmer’s hydrostatic and hydrodynamic profile, respectively. PMID:23486528

Velocity measurement of model vertical axis wind turbines

Energy Technology Data Exchange (ETDEWEB)

Johnson, D.A.; McWilliam, M. [Waterloo Univ., ON (Canada). Dept. of Mechanical Engineering

2006-07-01

An increasingly popular solution to future energy demand is wind energy. Wind turbine designs can be grouped according to their axis of rotation, either horizontal or vertical. Horizontal axis wind turbines have higher power output in a good wind regime than vertical axis turbines and are used in most commercial class designs. Vertical axis Savonius-based wind turbine designs are still widely used in some applications because of their simplistic design and low wind speed performance. There are many design variables that must be considered in order to optimize the power output in a given wind regime in a typical wind turbine design. Using particle image velocimetry, a study of the air flow around five different model vertical axis wind turbines was conducted in a closed loop wind tunnel. A standard Savonius design with two semi-circular blades overlapping, and two variations of this design, a deep blade and a shallow blade design were among the turbine models included in this study. It also evaluated alternate designs that attempt to increase the performance of the standard design by allowing compound blade curvature. Measurements were collected at a constant phase angle and also at random rotor orientations. It was found that evaluation of the flow patterns and measured velocities revealed consistent and stable flow patterns at any given phase angle. Large scale flow structures are evident in all designs such as vortices shed from blade surfaces. An important performance parameter was considered to be the ability of the flow to remain attached to the forward blade and redirect and reorient the flow to the following blade. 6 refs., 18 figs.

Characterization of the structure of the Salar de Atacama Basin through gravimetric profiles and interval velocity analysis.

Science.gov (United States)

Becerra, J.; Bascunan, S. A.; Maksymowicz, A.; Martínez, F.; Arriagada, C.

2017-12-01

The structure of the basins found in the Preandean Depression in the northern Central Andes has remained elusive, partly due to a poor understanding of the structural styles and stratigraphy beneath their surface. An independent approach to the multiple interpretations of seismic lines available is the analysis of 2D gravity profiles. An E-W profile was performed across the basin, closely matching the surficial trace of previous seismic lines. The profile shows three gravimetric lows, the most relevant being one beneath the Llano de la Paciencia- Cordillera de la Sal, comprised of deformed evaporitic and terrigenous deposits of Oligocene-Early Miocene age. The structure which bounds this gravity low has a steeper dip on its eastern side, bounding the eastern side of the Cordillera de la Sal, which is at odds with previous studies that interpreted its western contact with Cretaceous outcrops as the possible basin boundary. The 3-D analyses of seismic interval velocity data around the gravimetric survey reveal a major vertical contrast in the eastern portion of the profile, interpreted as the bottom of the evaporite successions, followed to the west by a complex, narrow and deep zone of low velocities. Westward, the Cretaceous rocks record higher velocities than its post-Paleocene counterparts, and an almost uniform increase in velocity with depth. The major gravity anomaly is closely related to the Cordillera de la Sal, which consists of an array of folds and reverse faults involving Oligocene to recent deposits. We propose that the faults which generated Oligocene extension are not at the western border of the basin, but around the Cordillera de la Sal, which is the result of Miocene inversion of the same system. Strike-slip deformation was also probably a major contributor in basin formation, as shown by the narrow yet deep shape of the depocenter.

A Remote Sensing Approach to Estimate Vertical Profile Classes of Phytoplankton in a Eutrophic Lake

Directory of Open Access Journals (Sweden)

Kun Xue

2015-10-01

Full Text Available The extension and frequency of algal blooms in surface waters can be monitored using remote sensing techniques, yet knowledge of their vertical distribution is fundamental to determine total phytoplankton biomass and understanding temporal variability of surface conditions and the underwater light field. However, different vertical distribution classes of phytoplankton may occur in complex inland lakes. Identification of the vertical profile classes of phytoplankton becomes the key and first step to estimate its vertical profile. The vertical distribution profile of phytoplankton is based on a weighted integral of reflected light from all depths and is difficult to determine by reflectance data alone. In this study, four Chla vertical profile classes (vertically uniform, Gaussian, exponential and hyperbolic were found to occur in three in situ vertical surveys (28 May, 19–24 July and 10–12 October in a shallow eutrophic lake, Lake Chaohu. We developed and validated a classification and regression tree (CART to determine vertical phytoplankton biomass profile classes. This was based on an algal bloom index (Normalized Difference algal Bloom Index, NDBI applied to both in situ remote sensing reflectance (Rrs and MODIS Rayleigh-corrected reflectance (Rrc data in combination with data of local wind speed. The results show the potential of retrieving Chla vertical profiles information from integrated information sources following a decision tree approach.

Use of acoustic backscatter and vertical velocity to estimate concentration and dynamics of suspended solids in Upper Klamath Lake, south-central Oregon: Implications for Aphanizomenon flos-aquae

Science.gov (United States)

Wood, Tamara M.; Gartner, Jeffrey W.

2010-01-01

Vertical velocity and acoustic backscatter measurements by acoustic Doppler current profilers were used to determine seasonal, subseasonal (days to weeks), and diel variation in suspended solids in a freshwater lake where massive cyanobacterial blooms occur annually. During the growing season, the suspended material in the lake is dominated by the buoyancy-regulating cyanobacteria, Aphanizomenon flos-aquae. Measured variables (water velocity, relative backscatter [RB], wind speed, and air and water temperatures) were averaged over the deployment season at each sample time of day to determine average diel cycles. Phase shifts between diel cycles in RB and diel cycles in wind speed, vertical water temperature differences (delta T(degree)), and horizontal current speeds were found by determining the lead or lag that maximized the linear correlation between the respective diel cycles. Diel cycles in RB were more in phase with delta T(degree) cycles, and, to a lesser extent, wind cycles, than to water current cycles but were out of phase with the cycle that would be expected if the vertical movement of buoyant cyanobacteria colonies was controlled primarily by light. Clear evidence of a diel cycle in vertical velocity was found only at the two deepest sites in the lake. Cycles of vertical velocity, where present, were out of phase with expected vertical motion of cyanobacterial colonies based on the theoretical cycle for light-driven vertical movement. This suggests that water column stability and turbulence were more important factors in controlling vertical distribution of colonies than light. Variations at subseasonal time scales were determined by filtering data to pass periods between 1.2 and 15 days. At subseasonal time scales, correlations between RB and currents or air temperature were consistent with increased concentration of cyanobacterial colonies near the surface when water column stability increased (higher air temperatures or weaker currents) and

A measurement system for vertical seawater profiles close to the air–sea interface

Directory of Open Access Journals (Sweden)

R. P. Sims

2017-09-01

Full Text Available This paper describes a near-surface ocean profiler, which has been designed to precisely measure vertical gradients in the top 10 m of the ocean. Variations in the depth of seawater collection are minimized when using the profiler compared to conventional CTD/rosette deployments. The profiler consists of a remotely operated winch mounted on a tethered yet free-floating buoy, which is used to raise and lower a small frame housing sensors and inlet tubing. Seawater at the inlet depth is pumped back to the ship for analysis. The profiler can be used to make continuous vertical profiles or to target a series of discrete depths. The profiler has been successfully deployed during wind speeds up to 10 m s−1 and significant wave heights up to 2 m. We demonstrate the potential of the profiler by presenting measured vertical profiles of the trace gases carbon dioxide and dimethylsulfide. Trace gas measurements use an efficient microporous membrane equilibrator to minimize the system response time. The example profiles show vertical gradients in the upper 5 m for temperature, carbon dioxide and dimethylsulfide of 0.15 °C, 4 µatm and 0.4 nM respectively.

Variation of velocity profile according to blood viscosity in a microfluidic channel

Science.gov (United States)

Yeom, Eunseop; Kang, Yang Jun; Lee, Sang-Joon

2014-11-01

The shear-thinning effect of blood flows is known to change blood viscosity. Since blood viscosity and motion of red blood cells (RBCs) are closely related, hemorheological variations have a strong influence on hemodynamic characteristics. Therefore, understanding on the relationship between the hemorheological and hemodynamic properties is importance for getting more detailed information on blood circulation in microvessels. In this study, the blood viscosity and velocity profiles in a microfluidic channel were systematically investigated. Rat blood was delivered in the microfluidic device which can measure blood viscosity by monitoring the flow-switching phenomenon. Velocity profiles of blood flows in the microchannel were measured by using a micro-particle image velocimetry (PIV) technique. Shape of velocity profiles measured at different flow rates was quantified by using a curve-fitting equation. It was observed that the shape of velocity profiles is highly correlated with blood viscosity. The study on the relation between blood viscosity and velocity profile would be helpful to understand the roles of hemorheological and hemodynamic properties in cardiovascular diseases. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP) (No. 2008-0061991).

The boundary condition for vertical velocity and its interdependence with surface gas exchange

Science.gov (United States)

Kowalski, Andrew S.

2017-07-01

The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w) in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E) and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface). This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example) but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux-gradient relationships (eddy diffusivities) requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube - with vapour transport into an overlying, horizontal airstream - was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

The Reliability of Individualized Load-Velocity Profiles.

Science.gov (United States)

Banyard, Harry G; Nosaka, K; Vernon, Alex D; Haff, G Gregory

2017-11-15

This study examined the reliability of peak velocity (PV), mean propulsive velocity (MPV), and mean velocity (MV) in the development of load-velocity profiles (LVP) in the full depth free-weight back squat performed with maximal concentric effort. Eighteen resistance-trained men performed a baseline one-repetition maximum (1RM) back squat trial and three subsequent 1RM trials used for reliability analyses, with 48-hours interval between trials. 1RM trials comprised lifts from six relative loads including 20, 40, 60, 80, 90, and 100% 1RM. Individualized LVPs for PV, MPV, or MV were derived from loads that were highly reliable based on the following criteria: intra-class correlation coefficient (ICC) >0.70, coefficient of variation (CV) ≤10%, and Cohen's d effect size (ES) 0.05) between trials, movement velocities, or between linear regression versus second order polynomial fits. PV 20-100% , MPV 20-90% , and MV 20-90% are reliable and can be utilized to develop LVPs using linear regression. Conceptually, LVPs can be used to monitor changes in movement velocity and employed as a method for adjusting sessional training loads according to daily readiness.

The boundary condition for vertical velocity and its interdependence with surface gas exchange

Directory of Open Access Journals (Sweden)

A. S. Kowalski

2017-07-01

Full Text Available The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface. This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux–gradient relationships (eddy diffusivities requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube – with vapour transport into an overlying, horizontal airstream – was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

Numerical calculation of velocity distribution near a vertical flat plate immersed in bubble flow

International Nuclear Information System (INIS)

Matsuura, Akihiro; Nakamura, Hajime; Horihata, Hideyuki; Hiraoka, Setsuro; Aragaki, Tsutomu; Yamada, Ikuho; Isoda, Shinji.

1992-01-01

Liquid and gas velocity distributions for bubble flow near a vertical flat plate were calculated numerically by using the SIMPLER method, where the flow was assumed to be laminar, two-dimensional, and at steady state. The two-fluid flow model was used in the numerical analysis. To calculate the drag force on a small bubble, Stokes' law for a rigid sphere is applicable. The dimensionless velocity distributions which were arranged with characteristic boundary layer thickness and maximum liquid velocity were adjusted with a single line and their forms were similar to that for single-phase wall-jet flow. The average wall shear stress derived from the velocity gradient at the plate wall was strongly affected by bubble diameter but not by inlet liquid velocity. The present dimensionless velocity distributions obtained numerically agreed well with previous experimental results, and the proposed numerical algorithm was validated. (author)

Velocity Profiles of Slow Blood Flow in a Narrow Tube

Science.gov (United States)

Chen, Jinyu; Huang, Zuqia; Zhuang, Fengyuan; Zhang, Hui

1998-04-01

A fractal model is introduced into the slow blood motion. When blood flows slowly in a narrow tube, red cell aggregation results in the formation of an approximately cylindrical core of red cells. By introducing the fractal model and using the power law relation between area fraction φ and distance from tube axis ρ, rigorous velocity profiles of the fluid in and outside the aggregated core and of the core itself are obtained analytically for different fractal dimensions. It shows a blunted velocity distribution for a relatively large fractal dimension (D ˜ 2), which can be observed in normal blood; a pathological velocity profile for moderate dimension (D = 1), which is similar to the Segre-Silberberg effect; and a parabolic profile for negligible red cell concentration (D = 0), which likes in the Poiseuille flow. The project supported by the National Basic Research Project "Nonlinear Science", National Natural Science Foundation of China and the State Education Commission through the Foundation of Doctoral Training

Magnetometer-inferred, Equatorial, Daytime Vertical ExB Drift Velocities Observed in the African Longitude Sector

Science.gov (United States)

Anderson, D. N.; Yizengaw, E.

2011-12-01

A recent paper has investigated the sharp longitude gradients in the dayside ExB drift velocities associated with the 4-cell, non-migrating structures thought to be connected with the eastward propagating, diurnal, non-migrating (DE3) tides. Observations of vertical ExB drift velocities obtained from the Ion Velocity Meter (IVM) on the Communication/Navigation Outage Forecast System (C/NOFS) satellite were obtained in the Western Pacific, Eastern Pacific, Peruvian and Atlantic sectors for a few days during the months of October, March and December, 2009. Respective ExB drift velocity gradients at the cell boundaries for these 4 longitude sectors were a.) -1.3m/sec/degree, b.) 3m/sec/degree, c.) -4m/sec/degree and d.) 1m/sec/degree and were observed on a day-to-day basis. In this talk, we estimate the longitude gradients in the dayside, vertical ExB drift velocities from magnetometer H-component observations in the African sector. We briefly describe the technique for obtaining realistic ExB drift velocities associated with the difference in the H-component values between a magnetometer on the magnetic equator and one off the magnetic equator at 6 to 9 degrees dip latitude (delta H). We present magnetometer-inferred, dayside ExB drift velocities obtained from the AMBER (African Meridian B-field Education and Research) magnetometer chain in the East Africa (Ethiopian) longitude sector and the West African (Nigerian) longitude sector. We compare the longitude gradients in ExB drift velocities in the African sector with the C/NOFS- observed longitude gradients mentioned above. We also discuss the advantages of using ground-based magnetometer observations to infer ExB drift velocities compared with the C/NOFS satellite observations.

Effects of Unsteady Flow Past An Infinite Vertical Plate With Variable ...

African Journals Online (AJOL)

The effects of unsteady flow past an infinite vertical plate with variable temperature and constant mass flux are investigated. Laplace transform technique is used to obtain velocity and concentration fields. The computation of the results indicates that the velocity profiles increase with increase in Grashof numbers, mass ...

Application of Depth-Averaged Velocity Profile for Estimation of Longitudinal Dispersion in Rivers

Directory of Open Access Journals (Sweden)

Mohammad Givehchi

2010-01-01

Full Text Available River bed profiles and depth-averaged velocities are used as basic data in empirical and analytical equations for estimating the longitudinal dispersion coefficient which has always been a topic of great interest for researchers. The simple model proposed by Maghrebi is capable of predicting the normalized isovel contours in the cross section of rivers and channels as well as the depth-averaged velocity profiles. The required data in Maghrebi’s model are bed profile, shear stress, and roughness distributions. Comparison of depth-averaged velocities and longitudinal dispersion coefficients observed in the field data and those predicted by Maghrebi’s model revealed that Maghrebi’s model had an acceptable accuracy in predicting depth-averaged velocity.

Techniques for obtaining velocity distributions of atoms or ions from Doppler-broadened spectral line profiles

International Nuclear Information System (INIS)

Moran, T.G.

1986-12-01

Analysis of the doppler-broadened profiles of spectral lines radiated by atoms or ions in plasmas yields information about their velocity distributions. Researchers have analysed profiles of lines radiated by atoms in isotropic velocity distributions in several ways, one being the inversion of the integral equation which relates the velocity distribution to the line profile. This inversion formula was derived for a separate application and was given to within an arbitrary multiplicative constant. This paper presents a new derivation which obtains the inversion exactly, using a method which is easily generalized for determination of anisotropic velocity distribution functions. The technique to obtain an anisotropic velocity distribution function from line profiles measured at different angles is outlined

Velocity profiles in idealized model of human respiratory tract

Science.gov (United States)

Elcner, J.; Jedelsky, J.; Lizal, F.; Jicha, M.

2013-04-01

This article deals with numerical simulation focused on velocity profiles in idealized model of human upper airways during steady inspiration. Three r gimes of breathing were investigated: Resting condition, Deep breathing and Light activity which correspond to most common regimes used for experiments and simulations. Calculation was validated with experimental data given by Phase Doppler Anemometry performed on the model with same geometry. This comparison was made in multiple points which form one cross-section in trachea near first bifurcation of bronchial tree. Development of velocity profile in trachea during steady inspiration was discussed with respect for common phenomenon formed in trachea and for future research of transport of aerosol particles in human respiratory tract.

Velocity profiles in idealized model of human respiratory tract

Directory of Open Access Journals (Sweden)

Jicha M.

2013-04-01

Full Text Available This article deals with numerical simulation focused on velocity profiles in idealized model of human upper airways during steady inspiration. Three r gimes of breathing were investigated: Resting condition, Deep breathing and Light activity which correspond to most common regimes used for experiments and simulations. Calculation was validated with experimental data given by Phase Doppler Anemometry performed on the model with same geometry. This comparison was made in multiple points which form one cross-section in trachea near first bifurcation of bronchial tree. Development of velocity profile in trachea during steady inspiration was discussed with respect for common phenomenon formed in trachea and for future research of transport of aerosol particles in human respiratory tract.

Modeling direction discrimination thresholds for yaw rotations around an earth-vertical axis for arbitrary motion profiles.

Science.gov (United States)

Soyka, Florian; Giordano, Paolo Robuffo; Barnett-Cowan, Michael; Bülthoff, Heinrich H

2012-07-01

Understanding the dynamics of vestibular perception is important, for example, for improving the realism of motion simulation and virtual reality environments or for diagnosing patients suffering from vestibular problems. Previous research has found a dependence of direction discrimination thresholds for rotational motions on the period length (inverse frequency) of a transient (single cycle) sinusoidal acceleration stimulus. However, self-motion is seldom purely sinusoidal, and up to now, no models have been proposed that take into account non-sinusoidal stimuli for rotational motions. In this work, the influence of both the period length and the specific time course of an inertial stimulus is investigated. Thresholds for three acceleration profile shapes (triangular, sinusoidal, and trapezoidal) were measured for three period lengths (0.3, 1.4, and 6.7 s) in ten participants. A two-alternative forced-choice discrimination task was used where participants had to judge if a yaw rotation around an earth-vertical axis was leftward or rightward. The peak velocity of the stimulus was varied, and the threshold was defined as the stimulus yielding 75 % correct answers. In accordance with previous research, thresholds decreased with shortening period length (from ~2 deg/s for 6.7 s to ~0.8 deg/s for 0.3 s). The peak velocity was the determining factor for discrimination: Different profiles with the same period length have similar velocity thresholds. These measurements were used to fit a novel model based on a description of the firing rate of semi-circular canal neurons. In accordance with previous research, the estimates of the model parameters suggest that velocity storage does not influence perceptual thresholds.

Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

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Luan Pan

2014-07-01

Full Text Available Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

Development of an autonomous vertical profiler for oceanographic studies

Digital Repository Service at National Institute of Oceanography (India)

Dabholkar, N.; Desa, E.; Afzulpurkar, S.; Madhan, R.; Mascarenhas, A.A.M.Q.; Navelkar, G.; Maurya, P.K.; Prabhudesai, S.; Nagvekar, S.; Martins, H.; Sawkar, G.; Fernandes, P.; Manoj, K.K.

groups. This paper is based on a concept patent on a thruster driven Autonomous Vertical profiler [AVP], and describes the developmental steps being taken on the integration of sensors, control electronics, communications and a Graphical User interface...

Air-water flow in a vertical pipe with sudden changes of superficial water velocity

International Nuclear Information System (INIS)

Horst-Michael Prasser; Eckhard Krepper; Thomas Frank

2005-01-01

Full text of publication follows: For further model development and the validation of CFD codes for two-phase flow applications experiments were carried out with a sudden change of the superficial velocity of water. The tests were performed in a vertical pipe of 51.2 mm diameter. The gas was injected through 19 capillaries of 0.8 mm inner diameter equally distributed over the cross section of the pipe. Measurements were taken by two wire-mesh sensors (24 x 24 points, 2500 Hz) mounted in a short distance (16 mm) behind each other. This sensor assembly was placed 3030 mm downstream of the gas injection. The change of the superficial water velocity was produced by a butterfly valve, the flap of which was perforated. In this way, a rapid closure of the valve caused a jump-like reduction of the liquid flow rate. The valve was located upstream of the gas injection. In a second series of tests a jump-like increase of the water flow rate was studied. Time sequences of the gas fraction profile were calculated from the wire-mesh sensor data over sampling periods of 0.2 s per profile. To increase the statistical reliability of the data, the transient was repeated several times and the data superposed (ensemble averaging). Gas velocity distributions were determined by correlation of the signals with the measurements of the second sensor. The tests enable the observation of the restructuring process of bubbly flow between two steady state conditions. The process is subdivided into three main stages: (1) the undisturbed flow before the velocity jump, (2) the passage of the bubbly flow formed under initial conditions, but travelling with the new velocity and (3) the bubbly flow generated under the new boundary conditions. Transient behaviour between these stages is reflected by the measured data. Special attention was paid to stage 2, where the radial gas fraction profiles change shape due to the excitation of the force balance acting on the bubbles. The experimental results for

POLARIZED LINE FORMATION IN NON-MONOTONIC VELOCITY FIELDS

Energy Technology Data Exchange (ETDEWEB)

Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bengaluru 560034 (India)

2016-12-10

For a correct interpretation of the observed spectro-polarimetric data from astrophysical objects such as the Sun, it is necessary to solve the polarized line transfer problems taking into account a realistic temperature structure, the dynamical state of the atmosphere, a realistic scattering mechanism (namely, the partial frequency redistribution—PRD), and the magnetic fields. In a recent paper, we studied the effects of monotonic vertical velocity fields on linearly polarized line profiles formed in isothermal atmospheres with and without magnetic fields. However, in general the velocity fields that prevail in dynamical atmospheres of astrophysical objects are non-monotonic. Stellar atmospheres with shocks, multi-component supernova atmospheres, and various kinds of wave motions in solar and stellar atmospheres are examples of non-monotonic velocity fields. Here we present studies on the effect of non-relativistic non-monotonic vertical velocity fields on the linearly polarized line profiles formed in semi-empirical atmospheres. We consider a two-level atom model and PRD scattering mechanism. We solve the polarized transfer equation in the comoving frame (CMF) of the fluid using a polarized accelerated lambda iteration method that has been appropriately modified for the problem at hand. We present numerical tests to validate the CMF method and also discuss the accuracy and numerical instabilities associated with it.

Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe

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A. Weigelt

2016-03-01

Full Text Available The knowledge of the vertical distribution of atmospheric mercury (Hg plays an important role in determining the transport and cycling of mercury. However, measurements of the vertical distribution are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS project, four vertical profiles were taken on board research aircraft (CASA-212 in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM and total gaseous mercury (TGM were measured with Tekran 2537X and Tekran 2537B analysers. In addition to the mercury measurements, SO2, CO, O3, NO, and NO2, basic meteorological parameters (pressure, temperature, relative humidity have been measured. Additional ground-based mercury measurements at the GMOS master site in Waldhof, Germany and measurements onboard the CARIBIC passenger aircraft were used to extend the profile to the ground and upper troposphere respectively. No vertical gradient was found inside the well-mixed boundary layer (variation of less than 0.1 ng m−3 at different sites, with GEM varying from location to location between 1.4 and 1.6 ng m−3 (standard temperature and pressure, STP: T  =  273.15 K, p  =  1013.25 hPa. At all locations GEM dropped to 1.3 ng m−3 (STP when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013 over Leipzig, Germany, with the CARIBIC measurements during ascent and descent to

Velocity of large bubble in liquid-solid mixture in a vertical tube

International Nuclear Information System (INIS)

Hamaguchi, H.; Sakaguchi, T.

1995-01-01

The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V o in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V * (=V/V o ), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V * decreases linearly against the volumetric solid fraction ε of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V * and ε is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid

Velocity of large bubble in liquid-solid mixture in a vertical tube

Energy Technology Data Exchange (ETDEWEB)

Hamaguchi, H.; Sakaguchi, T. [Kobe Univ., Kobe (Japan)

1995-09-01

The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V{sub o} in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V{sup *}(=V/V{sub o}), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V{sup *} decreases linearly against the volumetric solid fraction {epsilon} of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V{sup *} and {epsilon} is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid.

Modeling the vertical soil organic matter profile using Bayesian parameter estimation

NARCIS (Netherlands)

Braakhekke, M.C.; Wutzler, T.; Beer, C.; Kattge, J.; Schrumpf, M.; Schöning, I.; Hoosbeek, M.R.; Kruijt, B.; Kabat, P.

2012-01-01

The vertical distribution of soil organic matter (SOM) in the profile may constitute a significant factor for soil carbon cycling. However, the formation of the SOM profile is currently poorly understood due to equifinality, caused by the entanglement of several processes: input from roots, mixing

Modeling the vertical soil organic matter profile using Bayesian parameter estimation

NARCIS (Netherlands)

Braakhekke, M.C.; Wutzler, T.; Beer, C.; Kattge, J.; Schrumpf, M.; Ahrens, B.; Schoning, I.; Hoosbeek, M.R.; Kruijt, B.; Kabat, P.; Reichstein, M.

2013-01-01

The vertical distribution of soil organic matter (SOM) in the profile may constitute an important factor for soil carbon cycling. However, the formation of the SOM profile is currently poorly understood due to equifinality, caused by the entanglement of several processes: input from roots, mixing

Characteristics of low-mass-velocity vertical gas-liquid two-phase flow

International Nuclear Information System (INIS)

Adachi, Hiromichi; Abe, Yutaka; Kimura, Ko-ji

1995-01-01

In the present paper, characteristics of low mass velocity two-phase flow was analyzed based on a concept that pressure energy of two-phase flow is converted into acceleration work, gravitational work and frictional work, and the pressure energy consumption rate should be minimum at the stable two-phase flow condition. Experimental data for vertical upward air-water two-phase flow at atmospheric pressure was used to verify this concept and the turbulent model used in this method is optimized with the data. (author)

CAMEX-3 AIRBORNE VERTICAL ATMOSPHERE PROFILING SYSTEM (AVAPS) V1

Data.gov (United States)

National Aeronautics and Space Administration — The CAMEX-3 DC-8 Airborne Vertical Atmosphere Profiling System (AVAPS) uses dropwindsonde and Global Positioning System (GPS) receivers to measure the atmospheric...

Seismic velocity site characterization of 10 Arizona strong-motion recording stations by spectral analysis of surface wave dispersion

Science.gov (United States)

Kayen, Robert E.; Carkin, Brad A.; Corbett, Skye C.

2017-10-19

Vertical one-dimensional shear wave velocity (VS) profiles are presented for strong-motion sites in Arizona for a suite of stations surrounding the Palo Verde Nuclear Generating Station. The purpose of the study is to determine the detailed site velocity profile, the average velocity in the upper 30 meters of the profile (VS30), the average velocity for the entire profile (VSZ), and the National Earthquake Hazards Reduction Program (NEHRP) site classification. The VS profiles are estimated using a non-invasive continuous-sine-wave method for gathering the dispersion characteristics of surface waves. Shear wave velocity profiles were inverted from the averaged dispersion curves using three independent methods for comparison, and the root-mean-square combined coefficient of variation (COV) of the dispersion and inversion calculations are estimated for each site.

RADIALLY MAGNETIZED PROTOPLANETARY DISK: VERTICAL PROFILE

International Nuclear Information System (INIS)

Russo, Matthew; Thompson, Christopher

2015-01-01

This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field B r ∼ (10 −4 –10 −2 )(r/ AU) −2 G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ∼1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10 −8 M ⊙ yr −1 are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper

Geological affinity of reflecting boundaries in the intermediate structural stage of the Chu Sarysuyskiy depression based on results of vertical seismic profilling

Energy Technology Data Exchange (ETDEWEB)

Davydov, N.G.; Kiselevskiy, Yu.N.

1983-01-01

A computer (EVM) and an ASOI-VSP-SK program complex are used to analyze data from seismic exploration and acoustical logging with interval by interval calculation of the velocity every four meters. Vertical seismic profilling (VSP) results are used to identify all the upper layers as reference layers. The basic reference level, the third, which corresponds to the floor of the carbonate middle to upper Visean series, is not sustained due to the thin layered state of the terrigeneous section. Based on data from vertical seismic profilling, the reflected wave method (MOV) and the common depth point method (MOGT), the reference 3-a and 6-a levels are identified. Deep reflections of the seventh, 7-a and Rf, approximately confined to the roof and floor of the lower Paleozoic deposits and the upper part of the upper reef series, are noted in the series of the Caledonian cap of the Prebaykal massifs based on vertical seismic profilling. Collector levels are noted on the basis of the frequency of the wave spectra and from the absorption coefficient in the Testas structure and in other low amplitude structures. The insufficiency of the depth capability of the common depth point method and the poor knowledge level of seismic exploration of the section of the lower Paleozoa and the upper Proterozoa of the Chu Sarysuyskiy depresion are noted.

Vertical profiles of urban aerosol complex refractive index in the frame of ESQUIF airborne measurements

Science.gov (United States)

Raut, J.-C.; Chazette, P.

2008-02-01

A synergy between lidar, sunphotometer and in situ measurements has been applied to airborne observations performed during the Etude et Simulation de la QUalité de l'air en Ile-de-France (ESQUIF), enabling the retrieval of vertical profiles for the aerosol complex refractive index (ACRI) and single-scattering albedo with a vertical resolution of 200 m over Paris area. The averaged value over the entire planetary boundary layer (PBL) for the ACRI is close to 1.51(±0.02)-i0.017(±0.003) at 532 nm. The single-scattering albedo of the corresponding aerosols is found to be ~0.9 at the same wavelength. A good agreement is found with previous studies for urban aerosols. A comparison of vertical profiles of ACRI with simulations combining in situ measurements and relative humidity (RH) profiles has highlighted a modification in aerosol optical properties linked to their history and the origin of the air mass. The determination of ACRI in the atmospheric column enabled to retrieve vertical profiles of extinction coefficient in accordance with lidar profiles measurements.

Satellite-derived vertical profiles of temperature and dew point for mesoscale weather forecast

Science.gov (United States)

Masselink, Thomas; Schluessel, P.

1995-12-01

Weather forecast-models need spatially high resolutioned vertical profiles of temperature and dewpoint for their initialisation. These profiles can be supplied by a combination of data from the Tiros-N Operational Vertical Sounder (TOVS) and the imaging Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA polar orbiting sate!- lites. In cloudy cases the profiles derived from TOVS data only are of insufficient accuracy. The stanthrd deviations from radiosonde ascents or numerical weather analyses likely exceed 2 K in temperature and 5Kin dewpoint profiles. It will be shown that additional cloud information as retrieved from AVHIRR allows a significant improvement in theaccuracy of vertical profiles. The International TOVS Processing Package (ITPP) is coupled to an algorithm package called AVHRR Processing scheme Over cLouds, Land and Ocean (APOLLO) where parameters like cloud fraction and cloud-top temperature are determined with higher accuracy than obtained from TOVS retrieval alone. Furthermore, a split-window technique is applied to the cloud-free AVHRR imagery in order to derive more accurate surface temperatures than can be obtained from the pure TOVS retrieval. First results of the impact of AVHRR cloud detection on the quality of the profiles are presented. The temperature and humidity profiles of different retrieval approaches are validated against analyses of the European Centre for Medium-Range Weatherforecasts.

Vertical profiles of droplet effective radius in shallow convective clouds

Directory of Open Access Journals (Sweden)

S. Zhang

2011-05-01

>f_ad becomes smaller, representing a higher degree of mixing, and r_e becomes smaller (~10 % and more variable. However, for the clean case, smaller f_ad corresponds to larger r_e (and larger r_e variability, reflecting the additional influence of droplet collision-coalescence and sedimentation on r_e. Finally, profiles of the vertically inhomogeneous clouds as simulated by the LES and those of the vertically homogeneous clouds are used as input to a radiative transfer model to study the effect of cloud vertical inhomogeneity on shortwave radiative forcing. For clouds that have the same liquid water path, r_e of a vertically homogeneous cloud must be about 76–90 % of the cloud-top r_e of the vertically inhomogeneous cloud in order for the two clouds to have the same shortwave radiative forcing.

Mechanistic modelling of the vertical soil organic matter profile

NARCIS (Netherlands)

Braakhekke, M.C.

2014-01-01

Soil organic matter (SOM) constitutes a large global pool of carbon that may play a considerable role for future climate. The vertical distribution of SOM in the profile may be important due to depth-dependence of physical, chemical, and biological conditions, and links to physical processes

RADIALLY MAGNETIZED PROTOPLANETARY DISK: VERTICAL PROFILE

Energy Technology Data Exchange (ETDEWEB)

Russo, Matthew [Department of Physics, University of Toronto, 60 St. George St., Toronto, ON M5S 1A7 (Canada); Thompson, Christopher [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada)

2015-11-10

This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field B{sub r} ∼ (10{sup −4}–10{sup −2})(r/ AU){sup −2} G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ∼1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10{sup −8} M{sub ⊙} yr{sup −1} are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper.

Imaging water velocity and volume fraction distributions in water continuous multiphase flows using inductive flow tomography and electrical resistance tomography

International Nuclear Information System (INIS)

Meng, Yiqing; Lucas, Gary P

2017-01-01

This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas–water and oil–gas–water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the

Imaging water velocity and volume fraction distributions in water continuous multiphase flows using inductive flow tomography and electrical resistance tomography

Science.gov (United States)

Meng, Yiqing; Lucas, Gary P.

2017-05-01

This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas-water and oil-gas-water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the water

More vertical etch profile using a Faraday cage in plasma etching

Science.gov (United States)

Cho, Byeong-Ok; Hwang, Sung-Wook; Ryu, Jung-Hyun; Moon, Sang Heup

1999-05-01

Scanning electron microscope images of sidewalls obtained by plasma etching of an SiO2 film with and without a Faraday cage have been compared. When the substrate film is etched in the Faraday cage, faceting is effectively suppressed and the etch profile becomes more vertical regardless of the process conditions. This is because the electric potential in the cage is nearly uniform and therefore distortion of the electric field at the convex corner of a microfeature is prevented. The most vertical etch profile is obtained when the cage is used in fluorocarbon plasmas, where faceting is further suppressed due to the decrease in the chemical sputtering yield and the increase in the radical/ion flux on the substrate.

High resolution measurement of the velocity profiles of channel flows using the particle image velocimetry technique

International Nuclear Information System (INIS)

Nor Azizi Mohamed

2000-01-01

The high resolution velocity profiles of a uniform steady channel flow and a flow beneath waves were obtained using the particle image velocimetry (PIV) technique. The velocity profiles for each flow were calculated for both components. It is shown that the profiles obtained are very precise, displaying the point velocities from a few millimeters from the bottom of the channel up to the water surface across the water depth. In the case of the wave-induced flow, the profiles are shown under the respective wave phases and given in a plane representation. High resolution measurement of point velocities in a flow is achievable using PIV and invaluable when applied to a complex flow. (Author)

Results from a three-month intercomparison of boundary-layer wind profiler and sodar wind measurements at Lindenberg, Germany

Energy Technology Data Exchange (ETDEWEB)

Beyrich, F.; Goersdorf, U.; Neisser, J.; Steinhagen, H.; Weisensee, U. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorologisches Observatorium

1998-10-01

Intercomparison experiments with a wind profiler and a Doppler sodar have been performed at the meteorological observatory Lindenberg of the German weather service in summer, 1994, and in autumn, 1995, over a total period of about three months. The paper presents selected results of the wind measurements performed with the two systems. Sodar and wind profiler are shown to complement each other quite well. Therefore, a combination of both is a promising tool for continuous, high-resolution measurements of the wind profile. A problem to be solved is the construction of composite wind profiles when the measurements with the two systems disagree in the height range of overlapping. Measurements of the vertical velocity are difficult to assess due to their small absolute values. Long-term averages of the vertical velocity show slightly negative values, especially for the wind profiler. However, similar signatures have been found in the vertical velocity time series during frontal passages or during well-developed convection. (orig.) 7 refs.

Vertical Rise Velocity of Equatorial Plasma Bubbles Estimated from Equatorial Atmosphere Radar Observations and High-Resolution Bubble Model Simulations

Science.gov (United States)

Yokoyama, T.; Ajith, K. K.; Yamamoto, M.; Niranjan, K.

2017-12-01

Equatorial plasma bubble (EPB) is a well-known phenomenon in the equatorial ionospheric F region. As it causes severe scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPBs from a space weather point of view. The development of EPBs is presently believed as an evolution of the generalized Rayleigh-Taylor instability. We have already developed a 3D high-resolution bubble (HIRB) model with a grid spacing of as small as 1 km and presented nonlinear growth of EPBs which shows very turbulent internal structures such as bifurcation and pinching. As EPBs have field-aligned structures, the latitude range that is affected by EPBs depends on the apex altitude of EPBs over the dip equator. However, it was not easy to observe the apex altitude and vertical rise velocity of EPBs. Equatorial Atmosphere Radar (EAR) in Indonesia is capable of steering radar beams quickly so that the growth phase of EPBs can be captured clearly. The vertical rise velocities of the EPBs observed around the midnight hours are significantly smaller compared to those observed in postsunset hours. Further, the vertical growth of the EPBs around midnight hours ceases at relatively lower altitudes, whereas the majority of EPBs at postsunset hours found to have grown beyond the maximum detectable altitude of the EAR. The HIRB model with varying background conditions are employed to investigate the possible factors that control the vertical rise velocity and maximum attainable altitudes of EPBs. The estimated rise velocities from EAR observations at both postsunset and midnight hours are, in general, consistent with the nonlinear evolution of EPBs from the HIRB model.

Modeling of Aerosol Vertical Profiles Using GIS and Remote Sensing

Directory of Open Access Journals (Sweden)

Kwon Ho Lee

2009-06-01

Full Text Available The use of Geographic Information Systems (GIS and Remote Sensing (RS by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future.

Airborne Vertical Profiling of Mercury Speciation near Tullahoma, TN, USA

Directory of Open Access Journals (Sweden)

Steve Brooks

2014-08-01

Full Text Available Atmospheric transport and in situ oxidation are important factors influencing mercury concentrations at the surface and wet and dry deposition rates. Contributions of both natural and anthropogenic processes can significantly impact burdens of mercury on local, regional and global scales. To address these key issues in atmospheric mercury research, airborne measurements of mercury speciation and ancillary parameters were conducted over a region near Tullahoma, Tennessee, USA, from August 2012 to June 2013. Here, for the first time, we present vertical profiles of Hg speciation from aircraft for an annual cycle over the same location. These airborne measurements included gaseous elemental mercury (GEM, gaseous oxidized mercury (GOM and particulate bound mercury (PBM, as well as ozone (O3, sulfur dioxide (SO2, condensation nuclei (CN and meteorological parameters. The flights, each lasting ~3 h, were conducted typically one week out of each month to characterize seasonality in mercury concentrations. Data obtained from 0 to 6 km altitudes show that GEM exhibited a relatively constant vertical profile for all seasons with an average concentration of 1.38 ± 0.17 ng∙m−3. A pronounced seasonality of GOM was observed, with the highest GOM concentrations up to 120 pg∙m−3 in the summer flights and lowest (0–20 pg∙m−3 in the winter flights. Vertical profiles of GOM show the maximum levels at altitudes between 2 and 4 km. Limited PBM measurements exhibit similar levels to GOM at all altitudes. HYSPLIT back trajectories showed that the trajectories for elevated GOM (>70 pg∙m−3 or PBM concentrations (>30 pg∙m−3 were largely associated with air masses coming from west/northwest, while events with low GOM (<20 pg∙m−3 or PBM concentrations (<5 pg∙m−3 were generally associated with winds from a wider range of wind directions. This is the first set of speciated mercury vertical profiles collected in a single location over the course

Effects of Wind Velocity Driven by Alfven Waves on the Line Profiles for 32 CYG

Directory of Open Access Journals (Sweden)

Kyung-Mee Kim

1996-06-01

Full Text Available We calculate the theoretical line profiles for 32 Cyg in order to investigate the influence of various velocity fields. Line profiles are calculated with wind accelerations driven by Alfven waves and described by velocity parameters. The results for Alfvenic wave model show weakened line profiles. For the orbital phases ¥÷=0.78 and ¥÷=0.06 the Alfvenic models show strong absorption part due to very low densities at the surface of the supergiant. Hence, we conclude the velocity gradient of the wind near the supergiant could influence on the theoretical line formation.

A case study using kinematic quantities derived from a triangle of VHF Doppler wind profilers

Science.gov (United States)

Carlson, Catherine A.; Forbes, Gregory S.

1989-01-01

Horizontal divergence, relative vorticity, kinematic vertical velocity, and geostrophic and ageostrophic winds are computed from Colorado profiler network data to investigate an upslope snowstorm in northeastern Colorado. Horizontal divergence and relative vorticity are computed using the Gauss and Stokes theorems, respectively. Kinematic vertical velocities are obtained from the surface to 9 km by vertically integrating the continuity equation. The geostrophic and ageostrophic winds are computed by applying a finite differencing technique to evaluate the derivatives in the horizontal equations of motion. Comparison of the synoptic-scale data with the profiler network data reveals that the two datasets are generally consistent. Also, the profiler-derived quantities exhibit coherent vertical and temporal patterns consistent with conceptual and theoretical flow fields of various meteorological phenomena. It is suggested that the profiler-derived quantities are of potential use to weather forecasters in that they enable the dynamic and kinematic interpretation of weather system structure to be made and thus have nowcasting and short-term forecasting value.

Fatigue influences lower extremity angular velocities during a single-leg drop vertical jump

OpenAIRE

Tamura, Akihiro; Akasaka, Kiyokazu; Otsudo, Takahiro; Shiozawa, Junya; Toda, Yuka; Yamada, Kaori

2017-01-01

[Purpose] Fatigue alters lower extremity landing strategies and decreases the ability to attenuate impact during landing. The purpose of this study was to reveal the influence of fatigue on dynamic alignment and joint angular velocities in the lower extremities during a single leg landing. [Subjects and Methods] The 34 female college students were randomly assigned to either the fatigue or control group. The fatigue group performed single-leg drop vertical jumps before, and after, the fatigue...

Twilight vertical migrations of zooplankton in a Chilean fjord

Science.gov (United States)

Valle-Levinson, Arnoldo; Castro, Leonardo; Cáceres, Mario; Pizarro, Oscar

2014-12-01

Time series of acoustic backscatter and vertical velocity profiles were obtained at three sites along a Chilean fjord with the purpose of determining dominant structures of vertical migrations of the sound scattering layer. Ancillary data obtained with stratified net samples indicated that the sound scattering layer may have been dominated by euphausiids and decapods. Therefore, distributions of acoustic backscatter anomalies and vertical velocities were attributed to vertical migrations of predominantly these organisms. Migration patterns were dominated by twilight excursions in which organisms swam toward the water surface at sunset, spent 100 m). This migration strategy can also be termed 'semidiel migration' as two double excursions were linked to light levels. The reasons for this twilight migration remain uncertain. But it is possible that the up and down motion around sunset was related to predation avoidance, hunger-satiation state, ontogeny, seaward transport evasion, or reaction to the environmental shock from the pycnocline, or a combination of all or some of them. In contrast, the sunrise double excursion was probably linked to feeding requirements by organisms that need to spend the day at great depth with no food available. This study demonstrated the existence of semidiel patterns throughout the fjord and through prolonged periods. In addition, identification of this pattern by acoustic backscatter was complemented by direct vertical velocity measurements. It is proposed that twilight vertical migration is a common strategy in Chilean fjords.

Comparison of vertical E × B drift velocities and ground-based magnetometer observations of DELTA H in the low latitude under geomagnetically disturbed conditions

Science.gov (United States)

Prabhu, M.; Unnikrishnan, K.

2018-04-01

In the present work, we analyzed the daytime vertical E × B drift velocities obtained from Jicamarca Unattended Long-term Ionosphere Atmosphere (JULIA) radar and ΔH component of geomagnetic field measured as the difference between the magnitudes of the horizontal (H) components between two magnetometers deployed at two different locations Jicamarca, and Piura in Peru for 22 geomagnetically disturbed events in which either SC has occurred or Dstmax values of daytime vertical E × B drift velocity and peak value of ΔH for the three consecutive days of the events. It was observed that 45% of the events have daytime vertical E × B drift velocity peak in the magnitude range 10-20 m/s and 20-30 m/s and 20% have peak ΔH in the magnitude range 50-60 nT and 80-90 nT. It was observed that the time of occurrence of the peak value of both the vertical E × B drift velocity and the ΔH have a maximum (40%) probability in the same time range 11:00-13:00 LT. We also investigated the correlation between E × B drift velocity and Dst index and the correlation between delta H and Dst index. A strong positive correlation is found between E × B drift and Dst index as well as between delta H and Dst Index. Three different techniques of data analysis - linear, polynomial (order 2), and polynomial (order 3) regression analysis were considered. The regression parameters in all the three cases were calculated using the Least Square Method (LSM), using the daytime vertical E × B drift velocity and ΔH. A formula was developed which indicates the relationship between daytime vertical E × B drift velocity and ΔH, for the disturbed periods. The E × B drift velocity was then evaluated using the formulae thus found for the three regression analysis and validated for the 'disturbed periods' of 3 selected events. The E × B drift velocities estimated by the three regression analysis have a fairly good agreement with JULIA radar observed values under different seasons and solar activity

Using the Vertical Component of the Surface Velocity Field to Map the Locked Zone at Cascadia Subduction Zone

Science.gov (United States)

Moulas, E.; Brandon, M. T.; Podladchikov, Y.; Bennett, R. A.

2014-12-01

At present, our understanding of the locked zone at Cascadia subduction zone is based on thermal modeling and elastic modeling of horizontal GPS velocities. The thermal model by Hyndman and Wang (1995) provided a first-order assessment of where the subduction thrust might be cold enough for stick-slip behavior. The alternative approach by McCaffrey et al. (2007) is to use a Green's function that relates horizontal surface velocities, as recorded by GPS, to interseismic elastic deformation. The thermal modeling approach is limited by a lack of information about the amount of frictional heating occurring on the thrust (Molnar and England, 1990). The GPS approach is limited in that the horizontal velocity component is fairly insensitive to the structure of the locked zone. The vertical velocity component is much more useful for this purpose. We are fortunate in that vertical velocities can now be measured by GPS to a precision of about 0.2 mm/a. The dislocation model predicts that vertical velocities should range up to about 20 percent of the subduction velocity, which means maximum values of ~7 mm/a. The locked zone is generally entirely offshore at Cascadia, except for the Olympic Peninsula region, where the underlying Juan De Fuca plate has an anomalously low dip. Previous thermal and GPS modeling, as well as tide gauge data and episodic tremors indicate the locked zone there extends about 50 to 75 km onland. This situation provides an opportunity to directly study the locked zone. With that objective in mind, we have constructed a full 3D geodynamic model of the Cascadia subduction zone. At present, the model provides a full representation of the interseismic elastic deformation due to variations of slip on the subduction thrust. The model has been benchmarked against the Savage (2D) and Okada (3D) analytical solutions. This model has an important advantage over traditional dislocation modeling in that we include temperature-sensitive viscosity for the upper and

Constitutive Curve and Velocity Profile in Entangled Polymers during Start-Up of Steady Shear Flow

KAUST Repository

Hayes, Keesha A.

2010-05-11

Time-dependent shear stress versus shear rate, constitutive curve, and velocity profile measurements are reported in entangled polymer solutions during start-up of steady shear flow. By combining confocal microscopy and particle image velocimetry (PIV), we determine the time-dependent velocity profile in polybutadiene and polystyrene solutions seeded with fluorescent 150 nm silica and 7.5 μm melamine particles. By comparing these profiles with time-dependent constitutive curves obtained from experiment and theory, we explore the connection between transient nonmonotonic regions in the constitutive curve for an entangled polymer and its susceptibility to unstable flow by shear banding [Adams et al. Phys. Rev. Lett. 2009, 102, 067801-4]. Surprisingly, we find that even polymer systems which exhibit transient, nonmonotonic shear stress-shear rate relationships in bulk rheology experiments manifest time-dependent velocity profiles that are decidedly linear and show no evidence of unstable flow. We also report that interfacial slip plays an important role in the steady shear flow behavior of entangled polymers at shear rates above the reciprocal terminal relaxation time but has little, if any, effect on the shape of the velocity profile. © 2010 American Chemical Society.

High-Latitude Topside Ionospheric Vertical Electron Density Profile Changes in Response to Large Magnetic Storms

Science.gov (United States)

Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

2016-01-01

Large magnetic-storm-induced changes were detected in high-latitude topside vertical electron density profiles Ne(h) in a database of profiles and digital topside ionograms, from the International Satellites for Ionospheric Studies (ISIS) program, that enabled Ne(h) profiles to be obtained in nearly the same region of space before, during, and after a major magnetic storm (Dst -100nT). Storms where Ne(h) profiles were available in the high-latitude Northern Hemisphere had better coverage of solar wind parameters than storms with available Ne(h) profiles in the high-latitude Southern Hemisphere. Large Ne(h) changes were observed during all storms, with enhancements and depletions sometimes near a factor of 10 and 0.1, respectively, but with substantial differences in the responses in the two hemispheres. Large spatial andor temporal Ne(h) changes were often observed during Dst minimum and during the storm recovery phase. The storm-induced Ne(h) changes were the most pronounced and consistent in the Northern Hemisphere in that large enhancements were observed during winter nighttime and large depletions during winter and spring daytime. The limited available cases suggested that these Northern Hemisphere enhancements increased with increases of the time-shifted solar wind velocity v, magnetic field B, and with more negative values of the B components except for the highest common altitude (1100km) of the profiles. There was also some evidence suggesting that the Northern Hemisphere depletions were related to changes in the solar wind parameters. Southern Hemisphere storm-induced enhancements and depletions were typically considerably less with depletions observed during summer nighttime conditions and enhancements during summer daytime and fall nighttime conditions.

The velocity distribution caused by an airplane at the points of a vertical plane containing the span

Science.gov (United States)

Munk, Max M

1925-01-01

A formula for the computation of the vertical velocity component on all sides of an airplane is deduced and discussed. The formation is of value for the interpretation of such free flight tests where two airplanes fly alongside each other to facilitate observation.

Further experiments for mean velocity profile of pipe flow at high Reynolds number

Science.gov (United States)

Furuichi, N.; Terao, Y.; Wada, Y.; Tsuji, Y.

2018-05-01

This paper reports further experimental results obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to Reτ = 5.3 × 104. This high Reynolds number was achieved by using water as the working fluid and adopting a large-diameter pipe (387 mm) while controlling the flow rate and temperature with high accuracy and precision. The streamwise velocity was measured by laser Doppler velocimetry close to the wall, and the mean velocity profile, called log-law profile U+ = (1/κ) ln(y+) + B, is especially focused. After careful verification of the mean velocity profiles in terms of the flow rate accuracy and an evaluation of the consistency of the present results with those from previously measurements in a smaller pipe (100 mm), it was found that the value of κ asymptotically approaches a constant value of κ = 0.384.

Propagation velocity profile in a cross-section of a cardiac muscle bundle from PSpice simulation

Directory of Open Access Journals (Sweden)

Sperelakis Nicholas

2006-08-01

Full Text Available Abstract Background The effect of depth on propagation velocity within a bundle of cardiac muscle fibers is likely to be an important factor in the genesis of some heart arrhythmias. Model and methods The velocity profile of simulated action potentials propagated down a bundle of parallel cardiac muscle fibers was examined in a cross-section of the bundle using a PSpice model. The model (20 × 10 consisted of 20 chains in parallel, each chain being 10 cells in length. All 20 chains were stimulated simultaneously at the left end of the bundle using rectangular current pulses (0.25 nA, 0.25 ms duration applied intracellularly. The simulated bundle was symmetrical at the top and bottom (including two grounds, and voltage markers were placed intracellularly only in cells 1, 5 and 10 of each chain to limit the total number of traces to 60. All electrical parameters were standard values; the variables were (1 the number of longitudinal gap-junction (G-j channels (0, 1, 10, 100, (2 the longitudinal resistance between the parallel chains (Rol2 (reflecting the closeness of the packing of the chains, and (3 the bundle termination resistance at the two ends of the bundle (RBT. The standard values for Rol2 and RBT were 200 KΩ. Results The velocity profile was bell-shaped when there was 0 or only 1 gj-channel. With standard Rol2 and RBT values, the velocity at the surface of the bundle (θ1 and θ20 was more than double (2.15 × that at the core of the bundle (θ10, θ11. This surface:core ratio of velocities was dependent on the values of Rol2 and RBT. When Rol2 was lowered 10-fold, θ1 increased slightly and θ2decreased slightly. When there were 100 gj-channels, the velocity profile was flat, i.e. the velocity at the core was about the same as that at the surface. Both velocities were more than 10-fold higher than in the absence of gj-channels. Varying Rol2 and RBT had almost no effect. When there were 10 gj-channels, the cross-sectional velocity profile

Molecular dynamic simulation of Ar-Kr mixture across a rough walled nanochannel: Velocity and temperature profiles

International Nuclear Information System (INIS)

Pooja,; Ahluwalia, P. K.; Pathania, Y.

2015-01-01

This paper presents the results from a molecular dynamics simulation of mixture of argon and krypton in the Poiseuille flow across a rough walled nanochannel. The roughness effect on liquid nanoflows has recently drawn attention The computational software used for carrying out the molecular dynamics simulations is LAMMPS. The fluid flow takes place between two parallel plates and is bounded by horizontal rough walls in one direction and periodic boundary conditions are imposed in the other two directions. Each fluid atom interacts with other fluid atoms and wall atoms through Leenard-Jones (LJ) potential with a cut off distance of 5.0. To derive the flow a constant force is applied whose value is varied from 0.1 to 0.3 and velocity profiles and temperature profiles are noted for these values of forces. The velocity profile and temperature profiles are also looked at different channel widths of nanochannel and at different densities of mixture. The velocity profile and temperature profile of rough walled nanochannel are compared with that of smooth walled nanochannel and it is concluded that mean velocity increases with increase in channel width, force applied and decrease in density also with introduction of roughness in the walls of nanochannel mean velocity again increases and results also agree with the analytical solution of a Poiseuille flow

Analytical models of lateral power devices with arbitrary vertical doping profiles in the drift region

International Nuclear Information System (INIS)

Hua Ting-Ting; Guo Yu-Feng; Yu Ying; Jian Tong; Yao Jia-Fei; Sheu Gene

2013-01-01

By solving the 2D Poisson's equation, analytical models are proposed to calculate the surface potential and electric field distributions of lateral power devices with arbitrary vertical doping profiles. The vertical and the lateral breakdown voltages are formulized to quantify the breakdown characteristic in completely-depleted and partially-depleted cases. A new reduced surface field (RESURF) criterion which can be used in various drift doping profiles is further derived for obtaining the optimal trade-off between the breakdown voltage and the on-resistance. Based on these models and the numerical simulation, the electric field modulation mechanism and the breakdown characteristics of lateral power devices are investigated in detail for the uniform, linear, Gaussian, and some discrete doping profiles along the vertical direction in the drift region. Then, the mentioned vertical doping profiles of these devices with the same geometric parameters are optimized, and the results show that the optimal breakdown voltages and the effective drift doping concentrations of these devices are identical, which are equal to those of the uniform-doped device, respectively. The analytical results of these proposed models are in good agreement with the numerical results and the previous experimental results, confirming the validity of the models presented here. (interdisciplinary physics and related areas of science and technology)

Analytical models of lateral power devices with arbitrary vertical doping profiles in the drift region

Science.gov (United States)

Hua, Ting-Ting; Guo, Yu-Feng; Yu, Ying; Gene, Sheu; Jian, Tong; Yao, Jia-Fei

2013-05-01

By solving the 2D Poisson's equation, analytical models are proposed to calculate the surface potential and electric field distributions of lateral power devices with arbitrary vertical doping profiles. The vertical and the lateral breakdown voltages are formulized to quantify the breakdown characteristic in completely-depleted and partially-depleted cases. A new reduced surface field (RESURF) criterion which can be used in various drift doping profiles is further derived for obtaining the optimal trade-off between the breakdown voltage and the on-resistance. Based on these models and the numerical simulation, the electric field modulation mechanism and the breakdown characteristics of lateral power devices are investigated in detail for the uniform, linear, Gaussian, and some discrete doping profiles along the vertical direction in the drift region. Then, the mentioned vertical doping profiles of these devices with the same geometric parameters are optimized, and the results show that the optimal breakdown voltages and the effective drift doping concentrations of these devices are identical, which are equal to those of the uniform-doped device, respectively. The analytical results of these proposed models are in good agreement with the numerical results and the previous experimental results, confirming the validity of the models presented here.

Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

Science.gov (United States)

Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

2016-07-01

The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

Vertical profile of fog microphysics : a case study

Science.gov (United States)

Burnet, Frédéric; Brilouet, Pierre-Etienne; Mazoyer, Marie; Bourrianne, Thierry; Etcheberry, Jean-Michel; Gaillard, Brigitte; Legain, Dominique; Tzanos, Diane; Barrié, Joel; Barrau, Sébastien; Defoy, Stephan

2016-04-01

The occurrence and development of fogs result from the non-linear interaction of competing radiative, thermodynamic, microphysical and dynamical processes and the forecasting of their life cycle still remains a challenging issue. Several field campaigns have been carried out at the SIRTA observatory in the Paris suburb area (France). These experiments have shown that fog events exhibit large differences of the microphysical properties and various evolutions during their life cycle. To better understand relationships between the different processes and to validate numerical simulations it is necessary however to document the vertical profile of the fog microphysics. A CDP (Cloud Droplet Spectrometer) from DMT (Droplet Measurement Technology, Boulder, CO) has been modified to allow measurements of the droplet size distribution in fog layers with a tethered balloon. This instrumental set-up has been used during a field campaign during the winter 2013-214 in the Landes area in the South West of France. To validate the vertical profiles provided by the modified CDP, a mast was equipped with microphysical instruments at 2 altitude levels with an another CDP at 24 m and a Fog Monitor FM100 at 42 m. The instrumental set-up deployed during this campaign is presented. Data collected during a fog event that occurred during the night of 5-6 March 2014 are analysed. We show that microphysical properties such as droplet number concentration, LWC and mean droplet size, exhibit different time evolution during the fog life cycle depending on the altitude level. Droplet size distribution measurements are also investigated. They reveal sharp variations along the vertical close to the top of the fog layer. In addition it is shown that the shape of the size distributions at the top follows a time evolution typical of a quasi-adiabatic droplet growth.

Ground-based lidar and microwave radiometry synergy for high vertical resolution absolute humidity profiling

Science.gov (United States)

Barrera-Verdejo, María; Crewell, Susanne; Löhnert, Ulrich; Orlandi, Emiliano; Di Girolamo, Paolo

2016-08-01

Continuous monitoring of atmospheric humidity profiles is important for many applications, e.g., assessment of atmospheric stability and cloud formation. Nowadays there are a wide variety of ground-based sensors for atmospheric humidity profiling. Unfortunately there is no single instrument able to provide a measurement with complete vertical coverage, high vertical and temporal resolution and good performance under all weather conditions, simultaneously. For example, Raman lidar (RL) measurements can provide water vapor with a high vertical resolution, albeit with limited vertical coverage, due to sunlight contamination and the presence of clouds. Microwave radiometers (MWRs) receive water vapor information throughout the troposphere, though their vertical resolution is poor. In this work, we present an MWR and RL system synergy, which aims to overcome the specific sensor limitations. The retrieval algorithm combining these two instruments is an optimal estimation method (OEM), which allows for an uncertainty analysis of the retrieved profiles. The OEM combines measurements and a priori information, taking the uncertainty of both into account. The measurement vector consists of a set of MWR brightness temperatures and RL water vapor profiles. The method is applied to a 2-month field campaign around Jülich (Germany), focusing on clear sky periods. Different experiments are performed to analyze the improvements achieved via the synergy compared to the individual retrievals. When applying the combined retrieval, on average the theoretically determined absolute humidity uncertainty is reduced above the last usable lidar range by a factor of ˜ 2 with respect to the case where only RL measurements are used. The analysis in terms of degrees of freedom per signal reveal that most information is gained above the usable lidar range, especially important during daytime when the lidar vertical coverage is limited. The retrieved profiles are further evaluated using

Vertical profile of aerosols in the Himalayan region using an ultralight aircraft platform

Science.gov (United States)

Singh, A.; Mahata, K.; Rupakheti, M.; Lawrence, M. G.; Junkermann, W.

2017-12-01

Indo-gangetic plain (IGP) and Himalayan foothills have large spatial and temporal heterogeneity in aerosols characteristics. Regional meteorology around 850-500 mb plays an important role in the transformation and transportation of aerosols from west Asia to IGP, into Himalayan foothill, as well to high-altitude region of the Himalayas. In order to quantify the vertical and horizontal variation of aerosol properties in the Himalayan , an airborne campaign was carried out in the Pokhara Valley/Nepal (83°50'-84°10' E, 25°7'-28°15' N, 815 masl ) in two phases: test flights during May 2016 and an intensive airborne sampling flight in December-January 2017. This paper provides an overview of airborne measurement campaign from the first phase of measurements in May 2016. A two-seater microlight aircraft (IKARUS C 42) was used as the aerial platform. This was deemed the feasible option in Nepal for an aerial campaign; technical specification of the aircraft include an approximately 6 hrs of flying time, short-take off run, > 100 kgs of payload, suitable for spiral upward and downward profiling. The instrument package consist of GRIMM 1.108 for particle size distribution from 0.3 to 20 um at 6 seconds time resolution, and TSI CPC 3375 for total ultrafine particle (UFP) concentration at 1 s. The package also includes a Magee Scientific Aethalometer (AE42) for aerosol absorption at seven different wavelengths. Meteorological parameters include temperature and dew point at a sampling rate of 1 Hz or higher. The paper provides a snapshot of observed vertical profile (from 800 to 4500masl) of aerosols size, number and black carbon over one of populated mountain valley in Nepal during the pre-monsoon season. During the airborne measurement, local fires- mostly agriculture burn were observed, however no large scale forest fire was captured. Sharp morning and afternoon gradients were observed in the vertical profile for aerosol number and size, mostly dominated by 2000 masl

Nine-component vertical seismic profiling at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Balch, A.H.; Erdemir, C.; Spengler, R.W.; Hunter, W.C.

1996-01-01

Nine-component vertical seismic profiling has been conducted at the UE-25 UZ No. 16 borehole at Yucca Mountain, Nevada, in support of investigation of the hydrologic significance of fault and fracture systems. A large data set from multi-component sources and receivers allows state-of-the-art advances in processing using polarization filtering and reverse time migration, for enhanced interpretation of geologic features

The load-velocity profile differs more between men and women than between individuals with different strength levels.

Science.gov (United States)

Torrejón, Alejandro; Balsalobre-Fernández, Carlos; Haff, G Gregory; García-Ramos, Amador

2018-03-21

This study aimed to determine the suitability of the load-velocity relationship to prescribe the relative load (%1RM) in women, as well as to compare the load-velocity profile between sexes and participants with different strength levels. The load-velocity relationship of 14 men (1RM: 1.17 ± 0.19) and 14 women (1RM: 0.66 ± 0.13) were evaluated in the bench press exercise. The main findings revealed that: (I) the load-velocity relationship was always strong and linear (R 2 range: 0.987-0.993), (II) a steeper load-velocity profile was observed in men compared to women (Effect size [ES]: 1.09), with men showing higher velocities for light loads (ES: - 0.81 and - 0.40 for the y-intercept and 30%1RM, respectively), but women reporting higher velocities for the heavy loads (ES: 1.14 and 1.50 at 90%1RM and 100%1RM, respectively); and (III) while the slope of the load-velocity profile was moderately steeper for weak men compared to their strong counterpart (ES: 1.02), small differences were observed between strong and weak women (ES: - 0.39). While these results support the use of the individual load-velocity relationship to prescribe the %1RM in the bench press exercise for women, they also highlight the large disparities in their load-velocity profile compared to men.

Modeling the vertical soil organic matter profile using Bayesian parameter estimation

Directory of Open Access Journals (Sweden)

M. C. Braakhekke

2013-01-01

Full Text Available The vertical distribution of soil organic matter (SOM in the profile may constitute an important factor for soil carbon cycling. However, the formation of the SOM profile is currently poorly understood due to equifinality, caused by the entanglement of several processes: input from roots, mixing due to bioturbation, and organic matter leaching. In this study we quantified the contribution of these three processes using Bayesian parameter estimation for the mechanistic SOM profile model SOMPROF. Based on organic carbon measurements, 13 parameters related to decomposition and transport of organic matter were estimated for two temperate forest soils: an Arenosol with a mor humus form (Loobos, the Netherlands, and a Cambisol with mull-type humus (Hainich, Germany. Furthermore, the use of the radioisotope ²¹⁰Pb_ex as tracer for vertical SOM transport was studied. For Loobos, the calibration results demonstrate the importance of organic matter transport with the liquid phase for shaping the vertical SOM profile, while the effects of bioturbation are generally negligible. These results are in good agreement with expectations given in situ conditions. For Hainich, the calibration offered three distinct explanations for the observations (three modes in the posterior distribution. With the addition of ²¹⁰Pb_ex data and prior knowledge, as well as additional information about in situ conditions, we were able to identify the most likely explanation, which indicated that root litter input is a dominant process for the SOM profile. For both sites the organic matter appears to comprise mainly adsorbed but potentially leachable material, pointing to the importance of organo-mineral interactions. Furthermore, organic matter in the mineral soil appears to be mainly derived from root litter, supporting previous studies that highlighted the importance of root input for soil carbon sequestration. The ²¹⁰

Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

Science.gov (United States)

Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Cacciari, C.; Clementini, C.

2016-05-01

We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a least squares deconvolution (LSD) of the line profiles in order to an- alyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (+- 2 kms^-1) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 kms^-1 even with a low number of high- resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

Velocity profile measurement of lead-lithium flows by high-temperature ultrasonic doppler velocimetry

International Nuclear Information System (INIS)

Ueki, Y.; Kunugi, T.; Hirabayashi, Masaru; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Morley, N.B.

2014-01-01

This paper describes a high-temperature ultrasonic Doppler Velocimetry (HT-UDV) technique that has been successfully applied to measure velocity profiles of the lead-lithium eutectic alloy (PbLi) flows. The impact of tracer particles is investigated to determine requirements for HT-UDV measurement of PbLi flows. The HT-UDV system is tested on a PbLi flow driven by a rotating-disk in an inert atmosphere. We find that a sufficient amount of particles contained in the molten PbLi are required to successfully measure PbLi velocity profiles by HT-UDV. An X-ray diffraction analysis is performed to identify those particles in PbLi, and indicates that those particles were made of the lead mono-oxide (PbO). Since the specific densities of PbLi and PbO are close to each other, the PbO particles are expected to be well-dispersed in the bulk of molten PbLi. We conclude that the excellent dispersion of PbO particles enables in HT-UDV to obtain reliable velocity profiles for operation times of around 12 hours. (author)

Far-Field and Middle-Field Vertical Velocities Associated with Megathrust Earthquakes

Science.gov (United States)

Fleitout, L.; Trubienko, O.; Klein, E.; Vigny, C.; Garaud, J.; Shestakov, N.; Satirapod, C.; Simons, W. J.

2013-12-01

The recent megathrust earthquakes (Sumatra, Chili and Japan) have induced far-field postseismic subsidence with velocities from a few mm/yr to more than 1cm/yr at distances from 500 to 1500km from the earthquake epicentre, for several years following the earthquake. This subsidence is observed in Argentina, China, Korea, far-East Russia and in Malaysia and Thailand as reported by Satirapod et al. ( ASR, 2013). In the middle-field a very pronounced uplift is localized on the flank of the volcanic arc facing the trench. This is observed both over Honshu, in Chile and on the South-West coast of Sumatra. In Japan, the deformations prior to Tohoku earthquake are well measured by the GSI GPS network: While the East coast was slightly subsiding, the West coast was raising. A 3D finite element code (Zebulon-Zset) is used to understand the deformations through the seismic cycle in the areas surrounding the last three large subduction earthquakes. The meshes designed for each region feature a broad spherical shell portion with a viscoelastic asthenosphere. They are refined close to the subduction zones. Using these finite element models, we find that the pattern of the predicted far-field vertical postseismic displacements depends upon the thicknesses of the elastic plate and of the low viscosity asthenosphere. A low viscosity asthenosphere at shallow depth, just below the lithosphere is required to explain the subsidence at distances from 500 to 1500km. A thick (for example 600km) asthenosphere with a uniform viscosity predicts subsidence too far away from the trench. Slip on the subduction interface is unable tot induce the observed far-field subsidence. However, a combination of relaxation in a low viscosity wedge and slip or relaxation on the bottom part of the subduction interface is necessary to explain the observed postseismic uplift in the middle-field (volcanic arc area). The creep laws of the various zones used to explain the postseismic data can be injected in

PHL10/460: Cancerfacts.com - Vertical Portal with Newly Developed Health Profiler

OpenAIRE

Lenz, C; Brucksch, M

1999-01-01

Introduction Unlike general health portals such as WebMD and Drkoop.com that cover everything from the flu to heart disease, Silicon Valley-based cancerfacts.com is a so-called vertical portal. It covers only one small vertical niche of health care: cancer, and in particular, prostate cancer. As a value-added proprietary technology, the company offers its newly developed profile engine to health information retrievers. Methods Users are enabled to insert their specific medical information - r...

Fluid dynamics of air in a packed bed: velocity profiles and the continuum model assumption

Directory of Open Access Journals (Sweden)

NEGRINI A. L.

1999-01-01

Full Text Available Air flow through packed beds was analyzed experimentally under conditions ranging from those that reinforce the effect of the wall on the void fraction to those that minimize it. The packing was spherical particles, with a tube-to-particle diameter ratio (D/dp between 3 and 60. Air flow rates were maintained between 1.3 and 4.44 m3/min, and gas velocity was measured with a Pitot tube positioned above the bed exit. Measurements were made at various radial and angular coordinate values, allowing the distribution of air flow across the bed to be described in detail. Comparison of the experimentally observed radial profiles with those derived from published equations revealed that at high D/dp ratios the measured and calculated velocity profiles behaved similarly. At low ratios, oscillations in the velocity profiles agreed with those in the voidage profiles, signifying that treating the porous medium as a continuum medium is questionable in these cases.

Solutions of the Bogoliubov–de Gennes equation with position dependent Fermi-velocity and gap profiles

Energy Technology Data Exchange (ETDEWEB)

Presilla, M. [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Panella, O., E-mail: orlando.panella@pg.infn.it [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Roy, P. [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India)

2017-02-19

It is shown that bound state solutions of the one dimensional Bogoliubov–de Gennes (BdG) equation may exist when the Fermi velocity becomes dependent on the space coordinate. The existence of bound states in continuum (BIC) like solutions has also been confirmed both in the normal phase as well as in the super-conducting phase. We also show that a combination of Fermi velocity and gap parameter step-like profiles provides scattering solutions with normal reflection and transmission. - Highlights: • Bound states of BdG equation via Fermi velocity modulation. • Existence of bound states in continuum in both the normal and the superconducting phase. • Scattering solutions and bound states within a combination of step-like Fermi velocity and gap profiles.

Off-Nadir Hyperspectral Sensing for Estimation of Vertical Profile of Leaf Chlorophyll Content within Wheat Canopies.

Science.gov (United States)

Kong, Weiping; Huang, Wenjiang; Casa, Raffaele; Zhou, Xianfeng; Ye, Huichun; Dong, Yingying

2017-11-23

Monitoring the vertical profile of leaf chlorophyll (Chl) content within winter wheat canopies is of significant importance for revealing the real nutritional status of the crop. Information on the vertical profile of Chl content is not accessible to nadir-viewing remote or proximal sensing. Off-nadir or multi-angle sensing would provide effective means to detect leaf Chl content in different vertical layers. However, adequate information on the selection of sensitive spectral bands and spectral index formulas for vertical leaf Chl content estimation is not yet available. In this study, all possible two-band and three-band combinations over spectral bands in normalized difference vegetation index (NDVI)-, simple ratio (SR)- and chlorophyll index (CI)-like types of indices at different viewing angles were calculated and assessed for their capability of estimating leaf Chl for three vertical layers of wheat canopies. The vertical profiles of Chl showed top-down declining trends and the patterns of band combinations sensitive to leaf Chl content varied among different vertical layers. Results indicated that the combinations of green band (520 nm) with NIR bands were efficient in estimating upper leaf Chl content, whereas the red edge (695 nm) paired with NIR bands were dominant in quantifying leaf Chl in the lower layers. Correlations between published spectral indices and all NDVI-, SR- and CI-like types of indices and vertical distribution of Chl content showed that reflectance measured from 50°, 30° and 20° backscattering viewing angles were the most promising to obtain information on leaf Chl in the upper-, middle-, and bottom-layer, respectively. Three types of optimized spectral indices improved the accuracy for vertical leaf Chl content estimation. The optimized three-band CI-like index performed the best in the estimation of vertical distribution of leaf Chl content, with R² of 0.84-0.69, and RMSE of 5.37-5.56 µg/cm² from the top to the bottom layers

Slug Flow Analysis in Vertical Large Diameter Pipes

Science.gov (United States)

Roullier, David

The existence of slug flow in vertical co-current two-phase flow is studied experimentally and theoretically. The existence of slug flow in vertical direction implies the presence of Taylor bubbles separated by hydraulically sealed liquid slugs. Previous experimental studies such as Ombere-Ayari and Azzopardi (2007) showed the evidence of the non-existence of Taylor bubbles for extensive experimental conditions. Models developed to predict experimental behavior [Kocamustafaogullari et al. (1984), Jayanti and Hewitt. (1990) and Kjoolas et al. (2017)] suggest that Taylor bubbles may disappear at large diameters and high velocities. A 73-ft tall and 101.6-mm internal diameter test facility was used to conduct the experiments allowing holdup and pressure drop measurements at large L/D. Superficial liquid and gas velocities varied from 0.05-m/s to 0.2 m/s and 0.07 m/s to 7.5 m/s, respectively. Test section pressure varied from 38 psia to 84 psia. Gas compressibility effect was greatly reduced at 84 psia. The experimental program allowed to observe the flow patterns for flowing conditions near critical conditions predicted by previous models (air-water, 1016 mm ID, low mixture velocities). Flow patterns were observed in detail using wire-mesh sensor measurements. Slug-flow was observed for a narrow range of experimental conditions at low velocities. Churn-slug and churn-annular flows were observed for most of the experimental data-points. Cap-bubble flow was observed instead of bubbly flow at low vSg. Wire-mesh measurements showed that the liquid has a tendency to remain near to the walls. The standard deviation of radial holdup profile correlates to the flow pattern observed. For churn-slug flow, the profile is convex with a single maximum near the pipe center while it exhibits a concave shape with two symmetric maxima close to the wall for churn-annular flow. The translational velocity was measured by two consecutive wire-mesh sensor crosscorrelation. The results show

Recovery of Stokes waves from velocity measurements on an axis of symmetry

International Nuclear Information System (INIS)

Matioc, Bogdan-Vasile

2015-01-01

We provide a new method to recover the profile of Stokes waves, and more generally of waves with smooth vorticity, from measurements of the horizontal velocity component on a vertical axis of symmetry of the wave surface. Although we consider periodic waves only, the extension to solitary waves is straightforward. (paper)

Measurement for the MLC leaf velocity profile by considering the leaf leakage using a radiographic film

International Nuclear Information System (INIS)

Chow, James C L; Grigorov, Grigor N

2006-01-01

A method to measure the velocity profile of a multi-leaf collimator (MLC) leaf along its travel range using a radiographic film is reported by considering the intra-leaf leakage. A specific dynamic MLC field with leaves travelling from the field edge to the isocentre line was designed. The field was used to expose a radiographic film, which was then scanned, and the dose profile along the horizontal leaf axis was measured. The velocity at a sampling point on the film can be calculated by considering the horizontal distance between the sampling point and the isocentre line, dose at the sampling point, dose rate of the linear accelerator, the total leaf travel time from the field edge to isocentre line and the pre-measured dose rate of leaf leakage. With the leaf velocities and velocity profiles for all MLC leaves measured routinely, a comprehensive and simple QA for the MLC can be set up to test the consistency of the leaf velocity performance which is essential to the IMRT delivery using a sliding window technique. (note)

Transition of unsteady velocity profiles with reverse flow

OpenAIRE

Das, Debopam; Arakeri, Jaywant H

1998-01-01

This paper deals with the stability and transition to turbulence of wall-bounded unsteady velocity profiles with reverse flow. Such flows occur, for example, during unsteady boundary layer separation and in oscillating pipe flow. The main focus is on results from experiments in time-developing flow in a long pipe, which is decelerated rapidly. The flow is generated by the controlled motion of a piston. We obtain analytical solutions for laminar flow in the pipe and in a two-dimensional channe...

Vertical profiles of aerosol absorption coefficient from micro-Aethalometer data and Mie calculation over Milan.

Science.gov (United States)

Ferrero, L; Mocnik, G; Ferrini, B S; Perrone, M G; Sangiorgi, G; Bolzacchini, E

2011-06-15

Vertical profiles of aerosol number-size distribution and black carbon (BC) concentration were measured between ground-level and 500m AGL over Milan. A tethered balloon was fitted with an instrumentation package consisting of the newly-developed micro-Aethalometer (microAeth® Model AE51, Magee Scientific, USA), an optical particle counter, and a portable meteorological station. At the same time, PM(2.5) samples were collected both at ground-level and at a high altitude sampling site, enabling particle chemical composition to be determined. Vertical profiles and PM(2.5) data were collected both within and above the mixing layer. Absorption coefficient (b(abs)) profiles were calculated from the Aethalometer data: in order to do so, an optical enhancement factor (C), accounting for multiple light-scattering within the filter of the new microAeth® Model AE51, was determined for the first time. The value of this parameter C (2.05±0.03 at λ=880nm) was calculated by comparing the Aethalometer attenuation coefficient and aerosol optical properties determined from OPC data along vertical profiles. Mie calculations were applied to the OPC number-size distribution data, and the aerosol refractive index was calculated using the effective medium approximation applied to aerosol chemical composition. The results compare well with AERONET data. The BC and b(abs) profiles showed a sharp decrease at the mixing height (MH), and fairly constant values of b(abs) and BC were found above the MH, representing 17±2% of those values measured within the mixing layer. The BC fraction of aerosol volume was found to be lower above the MH: 48±8% of the corresponding ground-level values. A statistical mean profile was calculated, both for BC and b(abs), to better describe their behaviour; the model enabled us to compute their average behaviour as a function of height, thus laying the foundations for valid parametrizations of vertical profile data which can be useful in both remote sensing

Vertical profiles of black carbon concentration and particle number size distribution in the North China Plain

Science.gov (United States)

Ran, L.; Deng, Z.

2013-12-01

The vertical distribution of aerosols is of great importance to our understanding in the impacts of aerosols on radiation balance and climate, as well as air quality and public health. To better understand and estimate the effects of atmospheric components including trace gases and aerosols on atmospheric environment and climate, an intensive field campaign, Vertical Observations of trace Gases and Aerosols in the North China Plain (VOGA-NCP), was carried out from late July to early August 2013 over a rural site in the polluted NCP. During the campaign, vertical profiles of black carbon (BC) concentration and particle number size distribution were measured respectively by a micro-Aethalometer and an optical particle counter attached to a tethered balloon within 1000 m height. Meteorological parameters, including temperature, relative humidity, wind speed and wind direction, were measured simultaneously by a radiosonde also attached to the tethered balloon. Preliminary results showed distinct diurnal variations of the vertical distribution of aerosol total number concentration and BC concentration, following the development of the mixing layer. Generally, there was a well mixing of aerosols within the mixing layer and a sharp decrease above the mixing layer. Particularly, a small peak of BC concentrations was observed around 400-500 m height for several profiles. Further analysis would be needed to explain such phenomenon. It was also found that measured vertical profiles of BC using the filter-based method might be affected by the vertical distribution of relative humidity.

Field evaluation of a direct push deployed sensor probe for vertical soil water content profiling

Science.gov (United States)

Vienken, Thomas; Reboulet, Ed; Leven, Carsten; Kreck, Manuel; Zschornack, Ludwig; Dietrich, Peter

2015-04-01

Reliable high-resolution information about vertical variations in soil water content, i.e. total porosity in the saturated zone, is essential for flow and transport predictions within the subsurface. However, porosity measurements are often associated with high efforts and high uncertainties, e.g. caused by soil disturbance during sampling or sensor installation procedures. In hydrogeological practice, commonly applied tools for the investigation of vertical soil water content distribution include gravimetric laboratory analyses of soil samples and neutron probe measurements. A yet less well established technique is the use of direct push-deployed sensor probes. Each of these methods is associated with inherent advantages and limitations due to their underlying measurement principles and operation modes. The presented study describes results of a joint field evaluation of the individual methods under different depositional and hydrogeological conditions with special focus on the performance on the direct push-deployed water content profiler. Therefore, direct push-profiling results from three different test sites are compared with results obtained from gravimetric analysis of soil cores and neutron probe measurements. In direct comparison, the applied direct push-based sensor probe proved to be a suitable alternative for vertical soil water content profiling to neutron probe technology, and, in addition, proved to be advantageous over gravimetric analysis in terms vertical resolution and time efficiency. Results of this study identify application-specific limitations of the methods and thereby highlight the need for careful data evaluation, even though neutron probe measurements and gravimetric analyses of soil samples are well established techniques (see Vienken et al. 2013). Reference: Vienken, T., Reboulet, E., Leven, C., Kreck, M., Zschornack, L., Dietrich, P., 2013. Field comparison of selected methods for vertical soil water content profiling. Journal of

Waveform inversion of lateral velocity variation from wavefield source location perturbation

KAUST Repository

Choi, Yun Seok

2013-09-22

It is challenge in waveform inversion to precisely define the deep part of the velocity model compared to the shallow part. The lateral velocity variation, or what referred to as the derivative of velocity with respect to the horizontal distance, with well log data can be used to update the deep part of the velocity model more precisely. We develop a waveform inversion algorithm to obtain the lateral velocity variation by inverting the wavefield variation associated with the lateral shot location perturbation. The gradient of the new waveform inversion algorithm is obtained by the adjoint-state method. Our inversion algorithm focuses on resolving the lateral changes of the velocity model with respect to a fixed reference vertical velocity profile given by a well log. We apply the method on a simple-dome model to highlight the methods potential.

Experimental study of vertical stress profiles of a confined granular bed under static and dynamic conditions.

Science.gov (United States)

Mandato, S; Cuq, B; Ruiz, T

2012-07-01

In a wet agglomeration process inside a low shear mixer, the blade function is to induce i) homogenization of the liquid sprayed on the powder surface and ii) a stress field able to transfer the mechanical energy at the particle scale. In this work we study the mechanical state of a confined powder bed through the analysis of stress distributions (by force measurements) in a rectangular cell in two cases: for a classical model powder (i.e. glass beads) and a complex powder (i.e. wheat semolina). Two types of vertical stress profiles are obtained according to the type of measurements carried out in the powder bed, either locally (at different positions in the cell) or globally (at the entire base). The global vertical stress profile follows Janssen's model and the local vertical stress profile highlights a critical length, identified as the percolation threshold of the force network, and a shielding length near the bottom, which is similar to an influence length of the side walls. In the context of wet agglomeration, the results allow to consider the role of the characteristic lengths in the mixing bowl under vertical mechanical solicitation.

Tidal asymmetries of velocity and stratification over a bathymetric depression in a tropical inlet

Science.gov (United States)

Waterhouse, Amy F.; Valle-Levinson, Arnoldo; Morales Pérez, Rubén A.

2012-10-01

Observations of current velocity, sea surface elevation and vertical profiles of density were obtained in a tropical inlet to determine the effect of a bathymetric depression (hollow) on the tidal flows. Surveys measuring velocity profiles were conducted over a diurnal tidal cycle with mixed spring tides during dry and wet seasons. Depth-averaged tidal velocities during ebb and flood tides behaved according to Bernoulli dynamics, as expected. The dynamic balance of depth-averaged quantities in the along-channel direction was governed by along-channel advection and pressure gradients with baroclinic pressure gradients only being important during the wet season. The vertical structure of the along-channel flow during flood tides exhibited a mid-depth maximum with lateral shear enhanced during the dry season as a result of decreased vertical stratification. During ebb tides, along-channel velocities in the vicinity of the hollow were vertically sheared with a weak return flow at depth due to choking of the flow on the seaward slope of the hollow. The potential energy anomaly, a measure of the amount of energy required to fully mix the water column, showed two peaks in stratification associated with ebb tide and a third peak occurring at the beginning of flood. After the first mid-ebb peak in stratification, ebb flows were constricted on the seaward slope of the hollow resulting in a bottom return flow. The sinking of surface waters and enhanced mixing on the seaward slope of the hollow reduced the potential energy anomaly after maximum ebb. The third peak in stratification during early flood occurred as a result of denser water entering the inlet at mid-depth. This dense water mixed with ambient deep waters increasing the stratification. Lateral shear in the along-channel flow across the hollow allowed trapping of less dense water in the surface layers further increasing stratification.

Asymmetric Velocity Distributions from Halo Density Profiles in the Eddington Approach

International Nuclear Information System (INIS)

Vergados, J. D.

2015-01-01

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.

Employing Beam-Gas Interaction Vertices for Transverse Profile Measurements

CERN Document Server

Rihl, Mariana; Baglin, Vincent; Barschel, Colin; Bay, Aurelio; Blanc, Frederic; Bravin, Enrico; Bregliozzi, Giuseppe; Chritin, Nicolas; Dehning, Bernd; Ferro-Luzzi, Massimiliano; Gaspar, Clara; Gianì, Sebastiana; Giovannozzi, Massimo; Greim, Roman; Haefeli, Guido; Hopchev, Plamen; Jacobsson, Richard; Jensen, Lars; Jones, Owain Rhodri; Jurado, Nicolas; Kain, Verena; Karpinski, Waclaw; Kirn, Thomas; Kuhn, Maria; Luthi, Berengere; Magagnin, Paolo; Matev, Rosen; Nakada, Tatsuya; Neufeld, Niko; Panman, Jaap; Rakotomiaramanana, Barinjaka; Salustino Guimaraes, Valdir; Salvant, Benoit; Schael, Stefan; Schneider, Olivier; Schwering, Georg; Tobin, Mark; Veness, Raymond; Veyrat, Quentin; Vlachos, Sotiris; Wlochal, Michael; Xu, Zhirui; von Dratzig, Arndt

2016-01-01

Interactions of high-energy beam particles with residual gas offer a unique opportunity to measure the beam profile in a non-intrusive fashion. Such a method was successfully pioneered* at the LHCb experiment using a silicon microstrip vertex detector. During the recent Large Hadron Collider shutdown at CERN, a demonstrator Beam-Gas Vertexing system based on eight scintillating-fibre modules was designed**, constructed and installed on Ring 2 to be operated as a pure beam diagnostics device. The detector signals are read out and collected with LHCb-type front-end electronics and a DAQ system consisting of a CPU farm. Tracks and vertices will be reconstructed to obtain a beam profile in real time. Here, first commissioning results are reported. The advantages and potential for future applications of this technique are discussed.

Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

Science.gov (United States)

Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

2017-07-01

Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

Development of a Climatology of Vertically Complete Wind Profiles from Doppler Radar Wind Profiler Systems

Science.gov (United States)

Barbre, Robert E., Jr.

2015-01-01

This paper describes in detail the QC and splicing methodology for KSC's 50- and 915-MHz DRWP measurements that generates an extensive archive of vertically complete profiles from 0.20-18.45 km. The concurrent POR from each archive extends from April 2000 to December 2009. MSFC NE applies separate but similar QC processes to each of the 50- and 915-MHz DRWP archives. DRWP literature and data examination provide the basis for developing and applying the automated and manual QC processes on both archives. Depending on the month, the QC'ed 50- and 915-MHz DRWP archives retain 52-65% and 16-30% of the possible data, respectively. The 50- and 915-MHz DRWP QC archives retain 84-91% and 85-95%, respectively, of all the available data provided that data exist in the non- QC'ed archives. Next, MSFC NE applies an algorithm to splice concurrent measurements from both DRWP sources. Last, MSFC NE generates a composite profile from the (up to) five available spliced profiles to effectively characterize boundary layer winds and to utilize all possible 915-MHz DRWP measurements at each timestamp. During a given month, roughly 23,000-32,000 complete profiles exist from 0.25-18.45 km from the composite profiles' archive, and approximately 5,000- 27,000 complete profiles exist from an archive utilizing an individual 915-MHz DRWP. One can extract a variety of profile combinations (pairs, triplets, etc.) from this sample for a given application. The sample of vertically complete DRWP wind measurements not only gives launch vehicle customers greater confidence in loads and trajectory assessments versus using balloon output, but also provides flexibility to simulate different DOL situations across applicable altitudes. In addition to increasing sample size and providing more flexibility for DOL simulations in the vehicle design phase, the spliced DRWP database provides any upcoming launch vehicle program with the capability to utilize DRWP profiles on DOL to compute vehicle steering

CFD simulations of a bubbly flow in a vertical pipe

International Nuclear Information System (INIS)

Krepper, E.

2000-01-01

Even at the very simple conditions of two phase flow in a vertical pipe, strong 3D effects are observed. The distribution of the gas phase over the cross section varies significantly between the different flow patterns, which are known for the vertical two-phase flow. The air water flow in a vertical tube having a diameter of 50 mm and a length of about 3 m was investigated in steady state tests for different liquid and gas superficial velocities. Several two phase flow measuring techniques were used. Applying a wire mesh sensor, developed in FZR, the void fraction could be determined over the whole cross section of the pipe. The working principle is based on the measurement of the local instantaneous conductivity of the two-phase mixture. At the investigated flow velocities, the rate of the image acquisition is sufficient to record the same bubble several times. This enables to determine bubble diameter distributions. Applying two similar wire mesh sensors with a distance of 50 mm one above the other, the influence of the wire mesh to the flow could be investigated. No essential disturbances of the two-phase flow by the mesh could be found for the investigated flow regimes. Performing an auto correlation between the signals of both sensors, also profiles of the gas velocity were determined. In the CFD code CFX-4.2 several two-phase flow models were available. Using the code, volume fraction profiles were calculated and compared to the measured results for bubble flow regimes, to investigate the capability of these models (see also Krepper and Prasser [4] (1999)). (orig.)

Explicit wave action conservation for water waves on vertically sheared flows

Science.gov (United States)

Quinn, Brenda; Toledo, Yaron; Shrira, Victor

2016-04-01

Water waves almost always propagate on currents with a vertical structure such as currents directed towards the beach accompanied by an under-current directed back toward the deep sea or wind-induced currents which change magnitude with depth due to viscosity effects. On larger scales they also change their direction due to the Coriolis force as described by the Ekman spiral. This implies that the existing wave models, which assume vertically-averaged currents, is an approximation which is far from realistic. In recent years, ocean circulation models have significantly improved with the capability to model vertically-sheared current profiles in contrast with the earlier vertically-averaged current profiles. Further advancements have coupled wave action models to circulation models to relate the mutual effects between the two types of motion. Restricting wave models to vertically-averaged non-turbulent current profiles is obviously problematic in these cases and the primary goal of this work is to derive and examine a general wave action equation which accounts for these shortcoming. The formulation of the wave action conservation equation is made explicit by following the work of Voronovich (1976) and using known asymptotic solutions of the boundary value problem which exploit the smallness of the current magnitude compared to the wave phase velocity and/or its vertical shear and curvature. The adopted approximations are shown to be sufficient for most of the conceivable applications. This provides correction terms to the group velocity and wave action definition accounting for the shear effects, which are fitting for application to operational wave models. In the limit of vanishing current shear, the new formulation reduces to the commonly used Bretherton & Garrett (1968) no-shear wave action equation where the invariant is calculated with the current magnitude taken at the free surface. It is shown that in realistic oceanic conditions, the neglect of the vertical

Combined estimation of kappa and shear-wave velocity profile of the Japanese rock reference

Science.gov (United States)

Poggi, Valerio; Edwards, Benjamin; Fäh, Donat

2013-04-01

The definition of a common soil or rock reference is a key issue in probabilistic seismic hazard analysis (PSHA), microzonation studies, local site-response analysis and, more generally, when predicted or observed ground motion is compared for sites of different characteristics. A scaling procedure, which accounts for a common reference, is then necessary to avoid bias induced by the differences in the local geology. Nowadays methods requiring the definition of a reference condition generally prescribe the characteristic of a rock reference, calibrated using indirect estimation methods based on geology or on surface proxies. In most cases, a unique average shear-wave velocity value is prescribed (e.g. Vs30 = 800m/s as for class A of the EUROCODE8). Some attempts at defining the whole shape of a reference rock velocity profile have been described, often without a clear physical justification of how such a selection was performed. Moreover, in spite of its relevance in affecting the high-frequency part of the spectrum, the definition of the associated reference attenuation is in most cases missing or, when present, still remains quite uncertain. In this study we propose an approach that is based on the comparison between empirical anelastic amplification functions from spectral modeling of earthquakes and average S-wave velocities computed using the quarter-wavelength approach. The method is an extension of the approach originally proposed by Poggi et al. (2011) for Switzerland, and is here applied to Japan. For the analysis we make use of a selection of 36 stiff-soil and rock sites from the Japanese KiK-net network, for which a measured velocity profile is available. With respect to the previous study, however, we now analyze separately the elastic and anelastic contributions of the estimated empirical amplification. In a first step - which is consistent with the original work - only the elastic part of the amplification spectrum is considered. This procedure allows

Study on Rayleigh Wave Inversion for Estimating Shear-wave Velocity Profile

Directory of Open Access Journals (Sweden)

T.A. Sanny

2003-05-01

Full Text Available Rayleigh wave or ground roll is a noise in seismic body waves. However, how to use this noise for soil characterization is very interesting since Rayleigh wave phase velocity is a function of compression-wave velocity, shear-wave velocity, density and layer thickness. In layered-medium Rayleigh wave velocity also depends on wavelength or frequency, and this phenomenon is called dispersion. Inversion procedure to get shear-wave velocity profile needs a priori information about the solution of the problem to limit the unknown parameters. The Lagrange multiplier method was used to solve the constrained optimization problems or well known as a smoothing parameter in inversion problems. The advantage of our inversion procedure is that it can guarantee the convergence of solution even though the field data is incomplete, insufficient, and inconsistent. The addition of smoothing parameter can reduce the time to converge. Beside numerical stability, the statistical stability is also involved in inversion procedure. In field experiment we extracted ground roll data from seismic refraction record. The dispersion curves had been constructed by applying f-k analysis and f-k dip filtering. The dispersion curves show the dependence of Rayleigh wave phase velocities in layered media to frequency. The synthetic models also demonstrate the stability and the speed of inversion procedure.

Vertical dispersion from surface and elevated releases: An investigation of a Non-Gaussian plume model

International Nuclear Information System (INIS)

Brown, M.J.; Arya, S.P.; Snyder, W.H.

1993-01-01

The vertical diffusion of a passive tracer released from surface and elevated sources in a neutrally stratified boundary layer has been studied by comparing field and laboratory experiments with a non-Gaussian K-theory model that assumes power-law profiles for the mean velocity and vertical eddy diffusivity. Several important differences between model predictions and experimental data were discovered: (1) the model overestimated ground-level concentrations from surface and elevated releases at distances beyond the peak concentration; (2) the model overpredicted vertical mixing near elevated sources, especially in the upward direction; (3) the model-predicted exponent α in the exponential vertical concentration profile for a surface release [bar C(z)∝ exp(-z α )] was smaller than the experimentally measured exponent. Model closure assumptions and experimental short-comings are discussed in relation to their probable effect on model predictions and experimental measurements. 42 refs., 13 figs., 3 tabs

Importance of A Priori Vertical Ozone Profiles for TEMPO Air Quality Retrievals

Science.gov (United States)

Johnson, M. S.; Sullivan, J. T.; Liu, X.; Zoogman, P.; Newchurch, M.; Kuang, S.; McGee, T. J.; Leblanc, T.

2017-12-01

Ozone (O3) is a toxic pollutant which plays a major role in air quality. Typically, monitoring of surface air quality and O3 mixing ratios is conducted using in situ measurement networks. This is partially due to high-quality information related to air quality being limited from space-borne platforms due to coarse spatial resolution, limited temporal frequency, and minimal sensitivity to lower tropospheric and surface-level O3. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite is designed to address the limitations of current space-based platforms and to improve our ability to monitor North American air quality. TEMPO will provide hourly data of total column and vertical profiles of O3 with high spatial resolution to be used as a near-real-time air quality product. TEMPO O3 retrievals will apply the Smithsonian Astrophysical Observatory profile algorithm developed based on work from GOME, GOME-2, and OMI. This algorithm is suggested to use a priori O3 profile information from a climatological data-base developed from long-term ozone-sonde measurements (tropopause-based (TB-Clim) O3 climatology). This study evaluates the TB-Clim dataset and model simulated O3 profiles, which could potentially serve as a priori O3 profile information in TEMPO retrievals, from near-real-time data assimilation model products (NASA GMAO's operational GEOS-5 FP model and reanalysis data from MERRA2) and a full chemical transport model (CTM), GEOS-Chem. In this study, vertical profile products are evaluated with surface (0-2 km) and tropospheric (0-10 km) TOLNet observations and the theoretical impact of individual a priori profile sources on the accuracy of TEMPO O3 retrievals in the troposphere and at the surface are presented. Results indicate that while the TB-Clim climatological dataset can replicate seasonally-averaged tropospheric O3 profiles, model-simulated profiles from a full CTM resulted in more accurate tropospheric and surface-level O3 retrievals from

Simulation of air velocity in a vertical perforated air distributor

Science.gov (United States)

Ngu, T. N. W.; Chu, C. M.; Janaun, J. A.

2016-06-01

Perforated pipes are utilized to divide a fluid flow into several smaller streams. Uniform flow distribution requirement is of great concern in engineering applications because it has significant influence on the performance of fluidic devices. For industrial applications, it is crucial to provide a uniform velocity distribution through orifices. In this research, flow distribution patterns of a closed-end multiple outlet pipe standing vertically for air delivery in the horizontal direction was simulated. Computational Fluid Dynamics (CFD), a tool of research for enhancing and understanding design was used as the simulator and the drawing software SolidWorks was used for geometry setup. The main purpose of this work is to establish the influence of size of orifices, intervals between outlets, and the length of tube in order to attain uniformity of exit flows through a multi outlet perforated tube. However, due to the gravitational effect, the compactness of paddy increases gradually from top to bottom of dryer, uniform flow pattern was aimed for top orifices and larger flow for bottom orifices.

Vortex shedding induced by a solitary wave propagating over a submerged vertical plate

International Nuclear Information System (INIS)

Lin Chang; Ho, T.-C.; Chang, S.-C.; Hsieh, S.-C.; Chang, K.-A.

2005-01-01

Experimental study was conducted on the vortex shedding process induced by the interaction between a solitary wave and a submerged vertical plate. Particle image velocimetry (PIV) was used for quantitative velocity measurement while a particle tracing technique was used for qualitative flow visualization. Vortices are generated at the tip of each side of the plate. The largest vortices at each side of the plate eventually grow to the size of the water depth. Although the fluid motion under the solitary wave is only translatory, vortices are shed in both the upstream and downstream directions due to the interaction of the generated vortices as well as the vortices with the plate and the bottom. The process can be divided into four phases: the formation of a separated shear layer, the generation and shedding of vortices, the formation of a vertical jet, and the impingement of the jet onto the free surface. Similarity velocity profiles were found both in the separated shear layer and in the vertical jet

Temperature profiles in the Harwell boreholes

International Nuclear Information System (INIS)

Robins, N.S.

1983-03-01

Heat flow at Harwell is estimated at 45 mWm -2 (milli Watt per metre squared is the unit of heat flow). Thermal conductivity values for the formations penetrated range from 1.0 to 4.6 Wm -1 K -1 . The temperature profiles recorded in the boreholes enable the vertical groundwater flow patterns within two poorly permeable mudrock units to be evaluated. The two mudrock units act as leaky barriers each separating a pair of aquifer units which induce a vertical hydraulic gradient across the mudrocks. The flow velocity results for the upper mudrock units derived from the temperature profile are compatible with values for groundwater potential derived from hydraulic data (10 -9 ms -1 from the temperature profile and 10 -12 ms -1 from the hydraulic observations). The results from the lower mudrock sequence are incompatible and this may be due to some other overiding influence upon the temperature profile. (author)

Analysis of photonic spot profile converter and bridge structure on SOI platform for horizontal and vertical integration

Science.gov (United States)

Majumder, Saikat; Jha, Amit Kr.; Biswas, Aishik; Banerjee, Debasmita; Ganguly, Dipankar; Chakraborty, Rajib

2017-08-01

Horizontal spot size converter required for horizontal light coupling and vertical bridge structure required for vertical integration are designed on high index contrast SOI platform in order to form more compact integrated photonic circuits. Both the structures are based on the concept of multimode interference. The spot size converter can be realized by successive integration of multimode interference structures with reducing dimension on horizontal plane, whereas the optical bridge structure consists of a number of vertical multimode interference structure connected by single mode sections. The spot size converter can be modified to a spot profile converter when the final single mode waveguide is replaced by a slot waveguide. Analysis have shown that by using three multimode sections in a spot size converter, an Gaussian input having spot diameter of 2.51 μm can be converted to a spot diameter of 0.25 μm. If the output single mode section is replaced by a slot waveguide, this input profile can be converted to a flat top profile of width 50 nm. Similarly, vertical displacement of 8μm is possible by using a combination of two multimode sections and three single mode sections in the vertical bridge structure. The analyses of these two structures are carried out for both TE and TM modes at 1550 nm wavelength using the semi analytical matrix method which is simple and fast in computation time and memory. This work shows that the matrix method is equally applicable for analysis of horizontally as well as vertically integrated photonic circuit.

Elastic full-waveform inversion and parameterization analysis applied to walk-away vertical seismic profile data for unconventional (heavy oil) reservoir characterization

Science.gov (United States)

Pan, Wenyong; Innanen, Kristopher A.; Geng, Yu

2018-03-01

Seismic full-waveform inversion (FWI) methods hold strong potential to recover multiple subsurface elastic properties for hydrocarbon reservoir characterization. Simultaneously updating multiple physical parameters introduces the problem of interparameter tradeoff, arising from the covariance between different physical parameters, which increases nonlinearity and uncertainty of multiparameter FWI. The coupling effects of different physical parameters are significantly influenced by model parameterization and acquisition arrangement. An appropriate choice of model parameterization is critical to successful field data applications of multiparameter FWI. The objective of this paper is to examine the performance of various model parameterizations in isotropic-elastic FWI with walk-away vertical seismic profile (W-VSP) dataset for unconventional heavy oil reservoir characterization. Six model parameterizations are considered: velocity-density (α, β and ρ΄), modulus-density (κ, μ and ρ), Lamé-density (λ, μ΄ and ρ‴), impedance-density (IP, IS and ρ″), velocity-impedance-I (α΄, β΄ and I_P^'), and velocity-impedance-II (α″, β″ and I_S^'). We begin analyzing the interparameter tradeoff by making use of scattering radiation patterns, which is a common strategy for qualitative parameter resolution analysis. In this paper, we discuss the advantages and limitations of the scattering radiation patterns and recommend that interparameter tradeoffs be evaluated using interparameter contamination kernels, which provide quantitative, second-order measurements of the interparameter contaminations and can be constructed efficiently with an adjoint-state approach. Synthetic W-VSP isotropic-elastic FWI experiments in the time domain verify our conclusions about interparameter tradeoffs for various model parameterizations. Density profiles are most strongly influenced by the interparameter contaminations; depending on model parameterization, the inverted density

Elastic full-waveform inversion and parametrization analysis applied to walk-away vertical seismic profile data for unconventional (heavy oil) reservoir characterization

Science.gov (United States)

Pan, Wenyong; Innanen, Kristopher A.; Geng, Yu

2018-06-01

Seismic full-waveform inversion (FWI) methods hold strong potential to recover multiple subsurface elastic properties for hydrocarbon reservoir characterization. Simultaneously updating multiple physical parameters introduces the problem of interparameter trade-off, arising from the simultaneous variations of different physical parameters, which increase the nonlinearity and uncertainty of multiparameter FWI. The coupling effects of different physical parameters are significantly influenced by model parametrization and acquisition arrangement. An appropriate choice of model parametrization is important to successful field data applications of multiparameter FWI. The objective of this paper is to examine the performance of various model parametrizations in isotropic-elastic FWI with walk-away vertical seismic profile (W-VSP) data for unconventional heavy oil reservoir characterization. Six model parametrizations are considered: velocity-density (α, β and ρ΄), modulus-density (κ, μ and ρ), Lamé-density (λ, μ΄ and ρ‴), impedance-density (IP, IS and ρ″), velocity-impedance-I (α΄, β΄ and I_P^' }) and velocity-impedance-II (α″, β″ and I_S^' }). We begin analysing the interparameter trade-off by making use of scattering radiation patterns, which is a common strategy for qualitative parameter resolution analysis. We discuss the advantages and limitations of the scattering radiation patterns and recommend that interparameter trade-offs be evaluated using interparameter contamination kernels, which provide quantitative, second-order measurements of the interparameter contaminations and can be constructed efficiently with an adjoint-state approach. Synthetic W-VSP isotropic-elastic FWI experiments in the time domain verify our conclusions about interparameter trade-offs for various model parametrizations. Density profiles are most strongly influenced by the interparameter contaminations; depending on model parametrization, the inverted density

Accelerated and Decelerated Flows in a Circular Pipe : 1st Report, Velocity Profile and Friction Coefficient

OpenAIRE

Kurokawa, Junichi; Morikawa, Masahiro

1986-01-01

In order to determine the flow characteristics of a transient flow in a circular pipe, an accelerated and a decelerated flow are studied, and effects of acceleration upon the formation of a velocity profile, transition and a friction coefficient are determined for a wide range of accelerations. The results of the accelerated flow show that there are two patterns in the formation of a sectional velocity profile and transition, one of which is observed when the acceleration is relatively large ...

On vertical velocity fluctuations and internal tides in an upwelling region off the west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.; Antony, M.K.

.28 at 40 m (between two stations separated by a distance of 27 km), we obtain u a T/ax = 0.26 x 10m5 “C sP ‘. If the minimum value of AT over 1 h is taken as 0.3”C, aTlatz8.3 x lOA “C s-l, which is an order of Vertical velocity and internal tides 869 60...

Determination of Vertical Velocity Field of Southernmost Longitudinal Valley in Eastern Taiwan: A Joint Analysis of Leveling and GPS Measurements

Directory of Open Access Journals (Sweden)

Horng-Yue Chen

2012-01-01

Full Text Available In order to provide a detailed vertical velocity field in southernmost Longitudinal Valley where shows a complex three-fault system at the plate suture between Philippine Sea plate and Eurasia, we conducted leveling and GPS measurements, compiled data from previous surveys and combined them into a single data set. We compiled precise leveling results from 1984 to 2009, include 5 E-W trending and one N-S trending routes. We calculated the GPS vertical component from 10 continuous stations and from 89 campaign-mode stations from 1995 to 2010. The interseismic vertical rates are estimated by removing the co- and post-seismic effects of major large regional and nearby earthquakes. A stable continuous station S104 in the study area was adopted as the common reference station. We finally establish a map of the interseismic vertical velocity field. The interseismic vertical deformation was mainly accommodated by creeping/thrusting along two east-dipping strands of the three-fault system: the Luyeh and Lichi faults. The most dominant uplift of 30 mm yr-1 occurs at the hanging wall of the Lichi fault on the western Coastal Range. However the rate diminishes away from the fault in the hanging wall. The Quaternary tablelands inside of the Longitudinal Valley reveals uplift with a rate of 5 - 10 mm yr-1. Outside of the tablelands, the rest of the Longitudinal Valley flat area indicates substantial subsidence of -10 to -20 mm yr-1. Finally, it appears that the west-dipping blind fault under the eastern side of the Central Range does not play a significant role on interseismic deformation with subsidence rate of -5 to -10 mm yr-1.

Heat transfer effects on flow past an exponentially accelerated vertical plate with variable temperature

Directory of Open Access Journals (Sweden)

Muthucumaraswamy R.

2008-01-01

Full Text Available An exact solution to the problem of flow past an exponentially accelerated infinite vertical plate with variable temperature is analyzed. The temperature of the plate is raised linearly with time t. The dimensionless governing equations are solved using Laplace-transform technique. The velocity and temperature profiles are studied for different physical parameters like thermal Grashof number Gr, time and an accelerating parameter a. It is observed that the velocity increases with increasing values of a or Gr.

Velocity measurements and identification of the flow pattern of vertical air-water flows with light-beam detectors

International Nuclear Information System (INIS)

Luebbesmeyer, D.; Leoni, B.

1980-07-01

A new detector for measuring fluid velocities in two-phase flows by means of Noise-Analysis (especially Transient-Cross-Correlation-technique) has been developed. The detector utilizes a light-beam which is modulated by changes in the transparency of the two-phase flow. The results of nine measurements for different flow-regimes of vertical air/water-flows are shown. A main topic of these investigations was to answer the question if it is possible to identify the flow-pattern by looking at the shape of different 'Noise-Analytical-functions' (like APSD, CPSD, CCF etc.). The results prove that light-beam sensors are good detectors for fluid-velocity measurements in different flow regimes and in a wide range of fluid velocities starting with values of about 0.08 m/s up to values of 40 m/s. With respect to flow-pattern identification only the time-signals and the shape of the cross-power-density-function (CPSD) seem to be useful. (Auth.)

CFD simulations of a bubbly flow in a vertical pipe

International Nuclear Information System (INIS)

Krepper, E.

1999-01-01

Even at the very simple conditions of two phase flow in a vertical pipe, strong 3D effects are observed. The distribution of the gas phase over the cross section varies significantly between the different flow patterns, which are known for the vertical two-phase flow. The air water flow in a vertical tube having a diameter of 50 mm and a length of about 3 m was investigated in steady state tests for different liquid and gas superficial velocities. Several two phase flow measuring techniques were used. Applying a wire mesh sensor, developed in FZR, the void fraction could be determined over the whole cross section of the pipe. The working principle is based on the measurement of the local instantaneous conductivity of the two-phase mixture. At the investigated flow velocities, the rate of the image acquisition is sufficient to record the same bubble several times. This enables to determine bubble diameter distributions. Applying two similar wire mesh sensors with a distance of 50 mm one above the other, the influence of the wire mesh to the flow could be investigated. No essential disturbances of the two-phase flow by the mesh could be found for the investigated flow regimes. Performing an auto correlation between the signals of both sensors, also profiles of the gas velocity were determined. (orig.)

Differences in the Load-Velocity Profile Between 4 Bench-Press Variants.

Science.gov (United States)

García-Ramos, Amador; Pestaña-Melero, Francisco Luis; Pérez-Castilla, Alejandro; Rojas, Francisco Javier; Haff, Guy Gregory

2018-03-01

To compare the load-velocity relationship between 4 variants of the bench-press (BP) exercise. The full load-velocity relationship of 30 men was evaluated by means of an incremental loading test starting at 17 kg and progressing to the individual 1-repetition maximum (1RM) in 4 BP variants: concentric-only BP, concentric-only BP throw (BPT), eccentric-concentric BP, and eccentric-concentric BPT. A strong and fairly linear relationship between mean velocity (MV) and %1RM was observed for the 4 BP variants (r 2  > .96 for pooled data and r 2  > .98 for individual data). The MV associated with each %1RM was significantly higher in the eccentric-concentric technique than in the concentric-only technique. The only significant difference between the BP and BPT variants was the higher MV with the light to moderate loads (20-70%1RM) in the BPT using the concentric-only technique. MV was significantly and positively correlated between the 4 BP variants (r = .44-.76), which suggests that the subjects with higher velocities for each %1RM in 1 BP variant also tend to have higher velocities for each %1RM in the 3 other BP variants. These results highlight the need for obtaining specific equations for each BP variant and the existence of individual load-velocity profiles.

The Dynamics of M15: Observations of the Velocity Dispersion Profile and Fokker-Planck Models

Science.gov (United States)

Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.; Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.

1997-05-01

We report a new measurement of the velocity dispersion profile within 1' (3 pc) of the center of the globular cluster M15 (NGC 7078), using long-slit spectra from the 4.2 m William Herschel Telescope at La Palma Observatory. We obtained spatially resolved spectra for a total of 23 slit positions during two observing runs. During each run, a set of parallel slit positions was used to map out the central region of the cluster; the position angle used during the second run was orthogonal to that used for the first. The spectra are centered in wavelength near the Ca II infrared triplet at 8650 Å, with a spectral range of about 450 Å. We determined radial velocities by cross-correlation techniques for 131 cluster members. A total of 32 stars were observed more than once. Internal and external comparisons indicate a velocity accuracy of about 4 km s-1. The velocity dispersion profile rises from about σ = 7.2 +/- 1.4 km s-1 near 1' from the center of the cluster to σ = 13.9 +/- 1.8 km s-1 at 20". Inside of 20", the dispersion remains approximately constant at about 10.2 +/- 1.4 km s-1 with no evidence for a sharp rise near the center. This last result stands in contrast with that of Peterson, Seitzer, & Cudworth who found a central velocity dispersion of 25 +/- 7 km s-1, based on a line-broadening measurement. Our velocity dispersion profile is in good agreement with those determined in the recent studies of Gebhardt et al. and Dubath & Meylan. We have developed a new set of Fokker-Planck models and have fitted these to the surface brightness and velocity dispersion profiles of M15. We also use the two measured millisecond pulsar accelerations as constraints. The best-fitting model has a mass function slope of x = 0.9 (where 1.35 is the slope of the Salpeter mass function) and a total mass of 4.9 × 105 M⊙. This model contains approximately 104 neutron stars (3% of the total mass), the majority of which lie within 6" (0.2 pc) of the cluster center. Since the

Clogging of granular material in vertical pipes discharged at constant velocity

Directory of Open Access Journals (Sweden)

López-Rodríguez Diego

2017-01-01

Full Text Available We report an experimental study on the flow of spherical particles through a vertical pipe discharged at constant velocity by means of a conveyor belt placed at the bottom. For a pipe diameter 3.67 times the diameter of the particles, we observe the development of hanging arches that stop the flow as they are able to support the weight of the particles above them. We find that the distribution of times that it takes until a stable clog develops, decays exponentially. This is compatible with a clogging probability that remains constant during the discharge. We also observe that the probability of clogging along the pipe decreases with the height, i.e. most of the clogs are developed near the bottom. This spatial dependence may be attributed to different pressure values within the pipe which might also be related to a spontaneous development of an helical structure of the grains inside the pipe.

The influence of turbulence and vertical wind profile in wind turbine power curve

Energy Technology Data Exchange (ETDEWEB)

Honrubia, A.; Gomez-Lazaro, E. [Castilla-La Mancha Univ., Albacete (Spain). Renewable Energy Research Inst.; Vigueras-Rodriguez, A. [Albacete Science and Technolgy Park, Albacete (Spain)

2012-07-01

To identify the influence of turbulence and vertical wind profile in wind turbine performance, wind speed measurements at different heights have been performed. Measurements have been developed using a cup anemometer and a LIDAR equipment, specifically a pulsed wave one. The wind profile has been recorded to study the effect of the atmospheric conditions over the energy generated by a wind turbine located close to the LIDAR system. The changes in the power production of the wind turbine are relevant. (orig.)

Observation of E×B Flow Velocity Profile Change Using Doppler Reflectometry in HL-2A

Institute of Scientific and Technical Information of China (English)

XIAO Wei-Wen; ZOU Xiao-Lan; DING Xuan-Tong; DONG Jia-Qi; LIU Ze-Tian; SONG Shao-Dong; GAO Ya-Dong; YAO Liang-Hua; FENG Bei-Bin; SONG Xian-Ming; CHEN Cheng-Yuan; SUN Hong-Juan; LI Yong-Gao; YANG Qing-Wei; YAN Long-Wen; LIU Yi; DUAN Xu-Ru; PAN Chuan-Hong; LIU Yong

2009-01-01

A broadband,O-mode sweeping Doppler reflectometry designed for measuring plasma E×B flow velocity profiles is operated in HL-2A.The main feature of the Doppler reflectometry is its capability to be tuned to any selected frequency in total waveband from 26-40 GHz.This property enables us to probe several plasma layers within a short time interval during a discharge,permitting the characterization of the radial distribution of plasma fluctuations.The system allows us to extract important information about the velocity change layer,namely its spatial localization.In purely Ohmic discharge a change of the E×B flow velocity profiles has been observed in the region for 28 ＜ r ＜ 30cm if only the line average density exceeds 2.2×1019 m-3.The density gradient change is measured in the same region,too.

Local Void Fractions and Bubble Velocity in Vertical Air-Water Two-Phase Flows Measured by Needle-Contact Capacitance Probe

Directory of Open Access Journals (Sweden)

Shanfang Huang

2018-01-01

Full Text Available Multiphase flow measurements have become increasingly important in a wide range of industrial fields. In the present study, a dual needle-contact capacitance probe was newly designed to measure local void fractions and bubble velocity in a vertical channel, which was verified by digital high-speed camera system. The theoretical analyses and experiments show that the needle-contact capacitance probe can reliably measure void fractions with the readings almost independent of temperature and salinity for the experimental conditions. In addition, the trigger-level method was chosen as the signal processing method for the void fraction measurement, with a minimum relative error of −4.59%. The bubble velocity was accurately measured within a relative error of 10%. Meanwhile, dynamic response of the dual needle-contact capacitance probe was analyzed in detail. The probe was then used to obtain raw signals for vertical pipe flow regimes, including plug flow, slug flow, churn flow, and bubbly flow. Further experiments indicate that the time series of the output signals vary as the different flow regimes and are consistent with each flow structure.

Hemispheric aerosol vertical profiles: anthropogenic impacts on optical depth and cloud nuclei.

Science.gov (United States)

Clarke, Antony; Kapustin, Vladimir

2010-09-17

Understanding the effect of anthropogenic combustion upon aerosol optical depth (AOD), clouds, and their radiative forcing requires regionally representative aerosol profiles. In this work, we examine more than 1000 vertical profiles from 11 major airborne campaigns in the Pacific hemisphere and confirm that regional enhancements in aerosol light scattering, mass, and number are associated with carbon monoxide from combustion and can exceed values in unperturbed regions by more than one order of magnitude. Related regional increases in a proxy for cloud condensation nuclei (CCN) and AOD imply that direct and indirect aerosol radiative effects are coupled issues linked globally to aged combustion. These profiles constrain the influence of combustion on regional AOD and CCN suitable for challenging climate model performance and informing satellite retrievals.

Retrieving Vertical Air Motion and Raindrop Size Distributions from Vertically Pointing Doppler Radars

Science.gov (United States)

Williams, C. R.; Chandra, C. V.

2017-12-01

The vertical evolution of falling raindrops is a result of evaporation, breakup, and coalescence acting upon those raindrops. Computing these processes using vertically pointing radar observations is a two-step process. First, the raindrop size distribution (DSD) and vertical air motion need to be estimated throughout the rain shaft. Then, the changes in DSD properties need to be quantified as a function of height. The change in liquid water content is a measure of evaporation, and the change in raindrop number concentration and size are indicators of net breakup or coalescence in the vertical column. The DSD and air motion can be retrieved using observations from two vertically pointing radars operating side-by-side and at two different wavelengths. While both radars are observing the same raindrop distribution, they measure different reflectivity and radial velocities due to Rayleigh and Mie scattering properties. As long as raindrops with diameters greater than approximately 2 mm are in the radar pulse volumes, the Rayleigh and Mie scattering signatures are unique enough to estimate DSD parameters using radars operating at 3- and 35-GHz (Williams et al. 2016). Vertical decomposition diagrams (Williams 2016) are used to explore the processes acting on the raindrops. Specifically, changes in liquid water content with height quantify evaporation or accretion. When the raindrops are not evaporating, net raindrop breakup and coalescence are identified by changes in the total number of raindrops and changes in the DSD effective shape as the raindrops. This presentation will focus on describing the DSD and air motion retrieval method using vertical profiling radar observations from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility in Northern Oklahoma.

Investigation of the vertical nitrogen dioxide distribution above a frequented street

Energy Technology Data Exchange (ETDEWEB)

Malissa, H; Juette, W; Alidad, I

1975-01-01

Knowledge of the vertical nitrogen dioxide concentration profile in the atmosphere within a street canyon would enable the estimation of pollutant concentrations in street site living or working rooms and furthermore the calculation of pollutant concentrations at ground level from data measured at roof levels by means of long-line remote sensing methods. A formula was therefore derived under simplified conditions and examined by simultaneous measurements of the nitrogen dioxide concentration, wind velocity, and wind direction at roof level and ground level. The data thus obtained were average values for half an hour. The knowledge of the local vertical wind profile and the influence of the traffic density in neighboring urban areas is essential for the calculation. The verification of the derived model shows a correlation coefficient of r equals 0.88 between calculated and measured data.

Gas-hydrate concentration estimated from P- and S-wave velocities at the Mallik 2L-38 research well, Mackenzie Delta, Canada

Science.gov (United States)

Carcione, José M.; Gei, Davide

2004-05-01

We estimate the concentration of gas hydrate at the Mallik 2L-38 research site using P- and S-wave velocities obtained from well logging and vertical seismic profiles (VSP). The theoretical velocities are obtained from a generalization of Gassmann's modulus to three phases (rock frame, gas hydrate and fluid). The dry-rock moduli are estimated from the log profiles, in sections where the rock is assumed to be fully saturated with water. We obtain hydrate concentrations up to 75%, average values of 37% and 21% from the VSP P- and S-wave velocities, respectively, and 60% and 57% from the sonic-log P- and S-wave velocities, respectively. The above averages are similar to estimations obtained from hydrate dissociation modeling and Archie methods. The estimations based on the P-wave velocities are more reliable than those based on the S-wave velocities.

Global mapping of vertical injection profiles of wild-fire emission

Science.gov (United States)

Sofiev, M.; Vankevich, R.; Ermakova, T.; Hakkarainen, J.

2012-08-01

A problem of a characteristic vertical profile of smoke released from wild-land fires is considered. A methodology for bottom-up evaluation of this profile is suggested and a corresponding global dataset is calculated. The profile estimation is based on: (i) a semi-empirical formula for plume-top height recently suggested by the authors, (ii) MODIS satellite observations of active wild-land fires, and (iii) meteorological conditions evaluated at each fireplace using output of ECMWF weather prediction model. Plumes from all fires recorded globally during two arbitrarily picked years 2001 and 2008 are evaluated and their smoke injection profiles are estimated with a time step of 3 h. The resulting 4-dimensional dataset is split to day- and night-time subsets. Each of the subsets is projected to global grid with resolution 1° × 1° × 500 m, averaged to monthly level, and normalised with total emission. Evaluation of the obtained dataset was performed at several levels. Firstly, the quality of the semi-empirical formula for plume-top computations was evaluated using recent additions to the MISR fire plume-height dataset. Secondly, the obtained maps of injection profiles are compared with another global distribution available from literature. Thirdly, the upper percentiles of the profiles are compared with an independent dataset of space-based lidar CALIOP. Finally, the stability of the calculated profiles with regard to inter-annual variations of the fire activity and meteorological conditions is roughly estimated by comparing the sub-sets for 2001 and 2008.

Effects of parabolic motion on an isothermal vertical plate with constant mass flux

Directory of Open Access Journals (Sweden)

R. Muthucumaraswamy

2014-12-01

Full Text Available An analytical study of free convection flow near a parabolic started infinite vertical plate with isothermal in the presence of uniform mass flux was considered. The mathematical model is reduced to a system of linear partial differential equations for the velocity, the concentration and the temperature; the closed form exact solutions were obtained by the Laplace transform technique. The velocity, temperature and concentration profiles for the different parameters as thermal Grashof number Gr, mass Grashof number Gc, Prandtl number Pr, Schmidt number Sc and time t were graphed and the numerical values for the skin friction were as tabulated. It is observed that the velocity is enhanced as the time increased and the velocity is decreased as the Prandtl number increased.

Multifractal analysis of vertical profiles of soil penetration resistance at the field scale

Directory of Open Access Journals (Sweden)

G. M. Siqueira

2013-07-01

Full Text Available Soil penetration resistance (PR is widely used as an indirect indicator of soil strength. Soil PR is linked to basic soil properties and correlated to root growth and plant production, and as such it is extensively used as a practical tool for assessing soil compaction and to evaluate the effects of soil management. This study investigates how results from multifractal analysis can quantify key elements of depth-dependent soil PR profiles and how this information can be used at the field scale. We analysed multifractality of 50 PR vertical profiles, measured from 0 to 60 cm depth and randomly located on a 6.5 ha sugar cane field in northeastern Brazil. The scaling property of each profile was typified by singularity, and Rényi spectra estimated by the method of moments. The Hurst exponent was used to parameterize the autocorrelation of the vertical PR data sets. The singularity and Rènyi spectra showed that the vertical PR data sets exhibited a well-defined multifractal structure. Hurst exponent values were close to 1, ranging from 0.944 to 0.988, indicating strong persistence in PR variation with soil depth. Also, the Hurst exponent was negatively and significantly correlated to coefficient of variation (CV, skewness and maximum values of the depth-dependent PR. Multifractal analysis added valuable information to describe the spatial arrangement of depth-dependent penetrometer data sets, which was not taken into account by classical statistical indices. Multifractal parameters were mapped over the experimental field and compared with mean and maximum values of PR. Combination of spatial variability survey and multifractal analysis appear to be useful to manage soil compaction.

Multifractal analysis of vertical profiles of soil penetration resistance at the field scale

Science.gov (United States)

Siqueira, G. M.; Silva, E. F. F.; Montenegro, A. A. A.; Vidal Vázquez, E.; Paz-Ferreiro, J.

2013-07-01

Soil penetration resistance (PR) is widely used as an indirect indicator of soil strength. Soil PR is linked to basic soil properties and correlated to root growth and plant production, and as such it is extensively used as a practical tool for assessing soil compaction and to evaluate the effects of soil management. This study investigates how results from multifractal analysis can quantify key elements of depth-dependent soil PR profiles and how this information can be used at the field scale. We analysed multifractality of 50 PR vertical profiles, measured from 0 to 60 cm depth and randomly located on a 6.5 ha sugar cane field in northeastern Brazil. The scaling property of each profile was typified by singularity, and Rényi spectra estimated by the method of moments. The Hurst exponent was used to parameterize the autocorrelation of the vertical PR data sets. The singularity and Rènyi spectra showed that the vertical PR data sets exhibited a well-defined multifractal structure. Hurst exponent values were close to 1, ranging from 0.944 to 0.988, indicating strong persistence in PR variation with soil depth. Also, the Hurst exponent was negatively and significantly correlated to coefficient of variation (CV), skewness and maximum values of the depth-dependent PR. Multifractal analysis added valuable information to describe the spatial arrangement of depth-dependent penetrometer data sets, which was not taken into account by classical statistical indices. Multifractal parameters were mapped over the experimental field and compared with mean and maximum values of PR. Combination of spatial variability survey and multifractal analysis appear to be useful to manage soil compaction.

Unsteady natural convection flow past an accelerated vertical plate in a thermally stratified fluid

Directory of Open Access Journals (Sweden)

Deka Rudra Kt.

2009-01-01

Full Text Available An exact solution to one-dimensional unsteady natural convection flow past an infinite vertical accelerated plate, immersed in a viscous thermally stratified fluid is investigated. Pressure work term and the vertical temperature advection are considered in the thermodynamic energy equation. The dimensionless governing equations are solved by Laplace Transform techniques for the Prandtl number unity. The velocity and temperature profiles as well as the skin-friction and the rate of heat transfer are presented graphically and discussed the effects of the Grashof number Gr, stratification parameter S at various times t.

Relationships among cloud occurrence frequency, overlap, and effective thickness derived from CALIPSO and CloudSat merged cloud vertical profiles

Science.gov (United States)

Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

2010-01-01

A cloud frequency of occurrence matrix is generated using merged cloud vertical profiles derived from the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and cloud profiling radar. The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical profiles can be related by a cloud overlap matrix when the correlation length of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches random overlap with increasing distance separating cloud layers and that the probability of deviating from random overlap decreases exponentially with distance. One month of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat data (July 2006) support these assumptions, although the correlation length sometimes increases with separation distance when the cloud top height is large. The data also show that the correlation length depends on cloud top hight and the maximum occurs when the cloud top height is 8 to 10 km. The cloud correlation length is equivalent to the decorrelation distance introduced by Hogan and Illingworth (2000) when cloud fractions of both layers in a two-cloud layer system are the same. The simple relationships derived in this study can be used to estimate the top-of-atmosphere irradiance difference caused by cloud fraction, uppermost cloud top, and cloud thickness vertical profile differences.

Measurement of the near-wall velocity profile for a nanofluid flow inside a microchannel

Science.gov (United States)

Kanjirakat, Anoop; Sadr, Reza

2015-11-01

Hydrodynamics and anomalous heat transfer enhancements have been reported in the past for colloidal suspensions of nano-sized particles dispersed in a fluid (nanofluids). However, such augmentations may manifest itself by study of fluid flow characteristics near in the wall region. Present experimental study reports near-wall velocity profile for nanofluids (silicon dioxide nanoparticles in water) measured inside a microchannel. An objective-based nano-Particle Image Velocimetry (nPIV) technique is used to measure fluid velocity within three visible depths, O(100nm), from the wall. The near-wall fluid velocity profile is estimated after implementing the required corrections for optical properties and effects caused by hindered Brownian motion, wall-particle interactions, and non-uniform exponential illumination on the measurement technique. The fluid velocities of nanofluids at each of the three visible depths are observed to be higher than that of the base fluid resulting in a higher shear rate in this region. The relative increase in shear rates for nanofluids is believed to be the result of the near-wall shear-induced particle migration along with the Brownian motion of the nanoparticles. This research is funded by NPRP grant # 08-574-2-239 from the Qatar National Research Fund (a member of Qatar Foundation).

Radial profiles of velocity and pressure for condensation-induced hurricanes

International Nuclear Information System (INIS)

Makarieva, A.M.; Gorshkov, V.G.

2011-01-01

The Bernoulli integral in the form of an algebraic equation is obtained for the hurricane air flow as the sum of the kinetic energy of wind and the condensational potential energy. With an account for the eye rotation energy and the decrease of angular momentum towards the hurricane center it is shown that the theoretical profiles of pressure and velocity agree well with observations for intense hurricanes. The previous order of magnitude estimates obtained in pole approximation are confirmed.

Radial profiles of velocity and pressure for condensation-induced hurricanes

Science.gov (United States)

Makarieva, A. M.; Gorshkov, V. G.

2011-02-01

The Bernoulli integral in the form of an algebraic equation is obtained for the hurricane air flow as the sum of the kinetic energy of wind and the condensational potential energy. With an account for the eye rotation energy and the decrease of angular momentum towards the hurricane center it is shown that the theoretical profiles of pressure and velocity agree well with observations for intense hurricanes. The previous order of magnitude estimates obtained in pole approximation are confirmed.

Radial profiles of velocity and pressure for condensation-induced hurricanes

Energy Technology Data Exchange (ETDEWEB)

Makarieva, A.M., E-mail: ammakarieva@gmail.co [Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Gorshkov, V.G. [Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation)

2011-02-14

The Bernoulli integral in the form of an algebraic equation is obtained for the hurricane air flow as the sum of the kinetic energy of wind and the condensational potential energy. With an account for the eye rotation energy and the decrease of angular momentum towards the hurricane center it is shown that the theoretical profiles of pressure and velocity agree well with observations for intense hurricanes. The previous order of magnitude estimates obtained in pole approximation are confirmed.

Detailed investigation on the effect of wall spring stiffness on velocity profile in molecular dynamics simulation

International Nuclear Information System (INIS)

Namvar, S; Karimian, S M H

2012-01-01

In this paper, motion of 576 monatomic argon molecules is studied in a channel with two 2-layered wall molecules. The effect of wall spring stiffness (K) on maximum value of velocity profile is investigated in the channel. It was observed that for K −2 , there is a decrease in the maximum value of velocity profile with an increase in K. This observation has been already reported by Sofos et al. To investigate a wider range of spring stiffness, in this paper the value of K was increased to more than 500εσ −2 . In this range of wall spring stiffness the behavior of maximum value of velocity profile changed; it increased with an increase in K. In a separate simulation the external force applied to the molecules was also increased and the same non-monotonic behavior of maximum value of velocity was observed. To clarify the reason of this behavior, the concepts of original and effective wall are introduced and through several test it is inferred that the mentioned concepts are not successful to demonstrate the reason of such behavior. It is suggested to obtain non-dimensional parameters governing the simulation in order to investigate the effect of every involved parameter on such a behavior. It is finally concluded that while wall spring stiffness affects the maximum velocity magnitude within the flow, the interaction of the two has not been clearly shown yet. The behavior of the maximum velocity is non-monotonic with the change of K. This is why no specific criterion has been reported for suitable value of wall spring stiffness in molecular dynamics simulation.

Air velocity profiles near sleeve blockages in an unheated 7 x 7 rod bundle. [PWR

Energy Technology Data Exchange (ETDEWEB)

Creer, J. M.; Bates, J. M.

1979-04-01

Local air velocity measurements were obtained with a laser Doppler anemometer near flow blockages in an unheated 7 x 7 rod bundle. Sleeve blockages were positioned on the center nine rods to create an area reduction of 90% in the center four subchannels of the bundle. Experimental results indicated that severe flow disturbances occurred downstream from the blockage cluster but showed only minor flow disturbances upstream from the blockage. Flow reversals were detected downstream from the blockage and persisted for approximately five subchannel hydraulic diameters. The air velocity profiles were in excellent agreement with water velocity data previously obtained at essentially the same Reynolds number. Subchannel average velocity predictions obtained with the COBRA computer program were in good agreement with subchannel average velocities estimated using the measured local velocity data.

Development of three-dimensional phasic-velocity distribution measurement in a large-diameter pipe

International Nuclear Information System (INIS)

Kanai, Taizo; Furuya, Masahiro; Arai, Takahiro; Shirakawa, Kenetsu

2011-01-01

A wire-mesh sensor (WMS) can acquire a void fraction distribution at a high temporal and spatial resolution and also estimate the velocity of a vertical rising flow by investigating the signal time-delay of the upstream WMS relative to downstream. Previously, one-dimensional velocity was estimated by using the same point of each WMS at a temporal resolution of 1.0 - 5.0 s. The authors propose to extend this time series analysis to estimate the multi-dimensional velocity profile via cross-correlation analysis between a point of upstream WMS and multiple points downstream. Bubbles behave in various ways according to size, which is used to classify them into certain groups via wavelet analysis before cross-correlation analysis. This method was verified by air-water straight and swirl flows within a large-diameter vertical pipe. The results revealed that for the rising straight and swirl flows, large scale bubbles tend to move to the center, while the small bubble is pushed to the outside or sucked into the space where the large bubbles existed. Moreover, it is found that this method can estimate the rotational component of velocity of the swirl flow as well as measuring the multi-dimensional velocity vector at high temporal resolutions of 0.2s. (author)

Convenient method for estimating underground s-wave velocity structure utilizing horizontal and vertical components microtremor spectral ratio; Bido no suiheido/jogedo supekutoru hi wo riyoshita kan`i chika s ha sokudo kozo suiteiho

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, H; Yoshioka, M; Saito, T [Iwate University, Iwate (Japan). Faculty of Engineering

1996-05-01

Studies were conducted about the method of estimating the underground S-wave velocity structure by inversion making use of the horizontal/vertical motion spectral ratio of microtremors. For this purpose, a dynamo-electric velocity type seismograph was used, capable of processing the east-west, north-south, and vertical components integratedly. For the purpose of sampling the Rayleigh wave spectral ratio, one out of all the azimuths was chosen, whose horizontal motion had a high Fourier frequency component coherency with the vertical motions. For the estimation of the underground S-wave velocity structure, parameters (P-wave velocity, S-wave velocity, density, and layer thickness) were determined from the minimum residual sum of squares involving the observed microtremor spectral ratio and the theoretical value calculated by use of a model structure. The known boring data was utilized for the study of the S-wave velocity in the top layer, and it was determined using an S-wave velocity estimation formula for the Morioka area constructed using the N-value, depth, and geological classification. It was found that the optimum S-wave velocity structure even below the top layer well reflects the S-wave velocity obtained by the estimation formula. 5 refs., 6 figs.

Comparisons of Crosswind Velocity Profile Estimates Used in Fast-Time Wake Vortex Prediction Models

Science.gov (United States)

Pruis, Mathew J.; Delisi, Donald P.; Ahmad, Nashat N.

2011-01-01

Five methods for estimating crosswind profiles used in fast-time wake vortex prediction models are compared in this study. Previous investigations have shown that temporal and spatial variations in the crosswind vertical profile have a large impact on the transport and time evolution of the trailing vortex pair. The most important crosswind parameters are the magnitude of the crosswind and the gradient in the crosswind shear. It is known that pulsed and continuous wave lidar measurements can provide good estimates of the wind profile in the vicinity of airports. In this study comparisons are made between estimates of the crosswind profiles from a priori information on the trajectory of the vortex pair as well as crosswind profiles derived from different sensors and a regional numerical weather prediction model.

Alignment of stress, mean wind, and vertical gradient of the velocity vector

DEFF Research Database (Denmark)

Berg, Jacob; Mann, Jakob; Patton, E.G.

2012-01-01

In many applications in the atmospheric surface layer the turbulent-viscosity hypothesis is applied, i.e. the stress vector can be described through the vertical gradient of velocity. In the atmospheric surface layer, where the Coriolis force and baroclinic effects are considered negligible......, this is supposedly a good approximation. High resolution large-eddy simulation (LES) data show that it is indeed the case. Through analysis of WindCube lidar measurements accompanied by sonic measurements we show that this is, on the other hand, rarely the case in the real atmosphere. This might indicate that large...... of atmospheric boundary layer modeling. The measurements are from the Danish wind turbine test sites at Høvsøre. With theWindCube lidar we are able to reach heights of 250 meters and hence capture the entire atmospheric surface layer both in terms of wind speed and the direction of the mean stress vector....

Method of solution for the determination of the velocity profiles in turbulent flow through annular tobes

Energy Technology Data Exchange (ETDEWEB)

Schmal, M; Russo, Q [Rio de Janeiro Univ. (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Almeida, M S; Bozzo, S [Rio de Janeiro Univ. (Brazil). Instituto de Quimica

1975-03-01

A method of solutions is presented for the determination of the velocity profiles in turbulent flow through annular tubes, based on the Von Karman similarity theory developed by Quarmby. The parameters found by Quarmby appearing in the velocity profiles and determined experimentally by different authors were approximated by polynonial functions of variable degree, as function of the Reynolds numbers. The Runge-Kutta-Nystrom method was used in the integration of the differential equations and the systematic of solution is presented in a computer program. The calculated results were compared to the experimental date and presented a deviation of 10/sup -2/%.

Temperature and Relative Humidity Vertical Profiles within Planetary Boundary Layer in Winter Urban Airshed

Science.gov (United States)

Bendl, Jan; Hovorka, Jan

2017-12-01

The planetary boundary layer is a dynamic system with turbulent flow where horizontal and vertical air mixing depends mainly on the weather conditions and geomorphology. Normally, air temperature from the Earth surface decreases with height but inversion situation may occur, mainly during winter. Pollutant dispersion is poor during inversions so air pollutant concentration can quickly rise, especially in urban closed valleys. Air pollution was evaluated by WHO as a human carcinogen (mostly by polycyclic aromatic hydrocarbons) and health effects are obvious. Knowledge about inversion layer height is important for estimation of the pollution impact and it can give us also information about the air pollution sources. Temperature and relative humidity vertical profiles complement ground measurements. Ground measurements were conducted to characterize comprehensively urban airshed in Svermov, residential district of the city of Kladno, about 30 km NW of Prague, from the 2nd Feb. to the 3rd of March 2016. The Svermov is an air pollution hot-spot for long time benzo[a]pyrene (B[a]P) limit exceedances, reaching the highest B[a]P annual concentration in Bohemia - west part of the Czech Republic. Since the Svermov sits in a shallow valley, frequent vertical temperature inversion in winter and low emission heights of pollution sources prevent pollutant dispersal off the valley. Such orography is common to numerous small settlements in the Czech Republic. Ground measurements at the sports field in the Svermov were complemented by temperature and humidity vertical profiles acquired by a Vaisala radiosonde positioned at tethered He-filled balloon. Total number of 53 series of vertical profiles up to the height of 300 m was conducted. Meteorology parameters were acquired with 4 Hz frequency. The measurements confirmed frequent early-morning and night formation of temperature inversion within boundary layer up to the height of 50 m. This rather shallow inversion had significant

Analyses of Current And Wave Forces on Velocity Caps

DEFF Research Database (Denmark)

Christensen, Erik Damgaard; Buhrkall, Jeppe; Eskesen, Mark C. D.

2015-01-01

Velocity caps are often used in connection with for instance offshore intake sea water for the use of for cooling water for power plants or as a source for desalinization plants. The intakes can also be used for river intakes. The velocity cap is placed on top of a vertical pipe. The vertical pipe......) this paper investigates the current and wave forces on the velocity cap and the vertical cylinder. The Morison’s force model was used in the analyses of the extracted force time series in from the CFD model. Further the distribution of the inlet velocities around the velocity cap was also analyzed in detail...

Laminar free convection in a vertical tube with constant wall temperature considering the variation of fluid properties

International Nuclear Information System (INIS)

Senna, J.G.

1981-01-01

A model to analyze Laminar Free convection with variable properties in the entrance of a vertical open tube with constant wall temperature and for one Prandtl number (0.7), is studied. The velocity and temperature profiles are determined by finite difference methods for different rates of wall to ambient temperatures and different values of the velocity in the entrance of the tube. The results will be compared with those obtained in the same problem with constant properties. (Author) [pt

In vitro confocal micro-PIV measurements of blood flow in a square microchannel: the effect of the haematocrit on instantaneous velocity profiles.

Science.gov (United States)

Lima, Rui; Wada, Shigeo; Takeda, Motohiro; Tsubota, Ken-ichi; Yamaguchi, Takami

2007-01-01

A confocal microparticle image velocimetry (micro-PIV) system was used to obtain detailed information on the velocity profiles for the flow of pure water (PW) and in vitro blood (haematocrit up to 17%) in a 100-microm-square microchannel. All the measurements were made in the middle plane of the microchannel at a constant flow rate and low Reynolds number (Re=0.025). The averaged ensemble velocity profiles were found to be markedly parabolic for all the working fluids studied. When comparing the instantaneous velocity profiles of the three fluids, our results indicated that the profile shape depended on the haematocrit. Our confocal micro-PIV measurements demonstrate that the root mean square (RMS) values increase with the haematocrit implying that it is important to consider the information provided by the instantaneous velocity fields, even at low Re. The present study also examines the potential effect of the RBCs on the accuracy of the instantaneous velocity measurements.

Acoustic and Shear-Wave Velocities in Hydrate-Bearing Sediments Offshore Southwestern Taiwan: Tomography, Converted Waves Analysis and Reverse-Time Migration of OBS Records

Directory of Open Access Journals (Sweden)

Philippe Schnurle

2006-01-01

Full Text Available A 2.5-D combined seismic reflection and refraction survey has been conducted in the accretionary complex offshore of southwestern Taiwan where BSRs (Bottom Simulating Reflectors are highly concentrated and geochemical signals for the presence of gas hydrate are strong. In this study, we perform velocity analysis of the 6 4-component OBS (Ocean-Bottom Seismometer records along the southernmost transect of this seismic experiment. We utilize 3 independent methods in order to accurately determine the acoustic and shear-wave velocities of the sediments: 1-D Root Mean Square (RMS analysis of the P-P and P-S reflected events on individual datumed components, 2-D inversion of the P-P and P-S reflected and refracted events along the in-line transect, and 3-D acoustic inversion of the first arrivals. The principal sources of bias in the determination of the velocities are the 3-dimentional nature of the topography and the complexity of the underlying structures. The three methods result in consistent velocity profiles. Rapid lateral and vertical variations of the velocities are observed. We then investigate the large scale gas hydrate content through rock physic modeling: at the vertical of each OBS, shear-waves velocities are utilized to estimate the water-filled porosities, and the acoustic velocities predicted for a set of gas hydrate, quartz and clay contents are compared to the observed profiles.

Experimental Studies of Low-Pressure Turbine Flows and Flow Control. Streamwise Pressure Profiles and Velocity Profiles

Science.gov (United States)

Volino, Ralph

2012-01-01

faculties. The geometry corresponded to "Pak B" LPT airfoil. The test section simulated LPT flow in a passage. Three experimental studies were performed: (a) Boundary layer measurements for ten baseline cases under high and low freestream turbulence conditions at five Reynolds numbers of 25,000, 50,000, 100,000, 200,000, and 300,000, based on passage exit velocity and suction surface wetted length; (b) Passive flow control studies with three thicknesses of two-dimensional bars, and two heights of three-dimensional circular cylinders with different spanwise separations, at same flow conditions as the 10 baseline cases; (c) Active flow control with oscillating synthetic (zero net mass flow) vortex generator jets, for one case with low freestream turbulence and a low Reynolds number of 25,000. The Passive flow control was successful at controlling the separation problem at low Reynolds numbers, with varying degrees of success from case to case and varying levels of impact at higher Reynolds numbers. The active flow control successfully eliminated the large separation problem for the low Reynolds number case. Very detailed data was acquired using hot-wire anemometry, including single and two velocity components, integral boundary layer quantities, turbulence statistics and spectra, turbulent shear stresses and their spectra, and intermittency, documenting transition, separation and reattachment. Models were constructed to correlate the results. The report includes a summary of the work performed and reprints of the publications describing the various studies. The folders in this supplement contain processed data in ASCII format. Streamwise pressure profiles and velocity profiles are included. The velocity profiles were acquired using single sensor and cross sensor hot-wire probes which were traversed from the wall to the freestream at various streamwise locations. In some of the flow control cases (3D Trips and Jets) profiles were acquired at multiple spanwise locations.

MHD free convection and mass transfer flow over an infinite vertical porous plate with viscous dissipation

Directory of Open Access Journals (Sweden)

Poonia Hemant

2010-01-01

Full Text Available An unsteady, two-dimensional, hydromagnetic, laminar mixed convective boundary layer flow of an incompressible and electrically-conducting fluid along an infinite vertical plate embedded in the porous medium with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer are discussed. The results show that increased cooling (Gr > 0 of the plate and the Eckert number leads to a rise in the velocity profile. Also, an increase in Eckert number leads to an increase in the temperature. Effects of Sc on velocity and concentration are discussed and shown graphically.

Prediction of the Inlet Nozzle Velocity Profiles for the CANDU-6 Moderator Analysis

International Nuclear Information System (INIS)

Yoon, Churl; Park, Joo Hwan

2006-01-01

For the moderator analysis of the CANDU reactors in Korea, predicting local moderator subcooling in the Calandria vessels is one of the main concerns for the estimation of heat sink capability of moderator under LOCA transients. The moderator circulation pattern is determined by the combined forces of the inlet jet momentum and the buoyancy flow. Even though the inlet boundary condition plays an important role in determining the moderator circulations, no measured data of detailed inlet velocity profiles is available. The purpose of this study is to produce the velocity profiles at the inlet nozzles by a CFD simulation. To produce the velocity vector fields at the inlet nozzle surfaces, the internal flows in the nozzle assembly were simulated by using a commercial CFD code, CFX-5.7. In the reference, the analytical capability of CFX-5.7 had been estimated by a validation of the CFD code against available experimental data for separate flow phenomena. Various turbulence models and grid spacing had been also tested. In the following section, the interface treatment between the computational domains would be explained. In section 3, the inlet nozzle flow through the CANDU moderator nozzle assembly was predicted by using the obtained technology of the CFD simulation

Determination of wall shear stress from mean velocity and Reynolds shear stress profiles

Science.gov (United States)

Volino, Ralph J.; Schultz, Michael P.

2018-03-01

An analytical method is presented for determining the Reynolds shear stress profile in steady, two-dimensional wall-bounded flows using the mean streamwise velocity. The method is then utilized with experimental data to determine the local wall shear stress. The procedure is applicable to flows on smooth and rough surfaces with arbitrary pressure gradients. It is based on the streamwise component of the boundary layer momentum equation, which is transformed into inner coordinates. The method requires velocity profiles from at least two streamwise locations, but the formulation of the momentum equation reduces the dependence on streamwise gradients. The method is verified through application to laminar flow solutions and turbulent DNS results from both zero and nonzero pressure gradient boundary layers. With strong favorable pressure gradients, the method is shown to be accurate for finding the wall shear stress in cases where the Clauser fit technique loses accuracy. The method is then applied to experimental data from the literature from zero pressure gradient studies on smooth and rough walls, and favorable and adverse pressure gradient cases on smooth walls. Data from very near the wall are not required for determination of the wall shear stress. Wall friction velocities obtained using the present method agree with those determined in the original studies, typically to within 2%.

Retrieval of vertical concentration profiles from OSIRIS UV-visible limb spectra

International Nuclear Information System (INIS)

Strong, K.; Joseph, B.M.; Dosanjh, R.; McDade, I.C.; McLinden, C.A.; McConnell, J.C.; Stegman, J.; Murtagh, D.P.; Llewellyn, E.J.

2002-01-01

The OSIRIS instrument, launched on the Odin satellite in February 2001, includes an optical spectrograph that will record UV-visible spectra of sunlight scattered from the limb over a range of tangent heights. These spectra will be used to retrieve vertical profiles of ozone, NO 2 , OC1O, BrO, NO 3 , O 2 , and aerosols, for the investigation of both stratospheric and mesospheric processes, particularly those related to ozone chemistry. In this work, the retrieval of vertical profiles of trace-gas concentrations from OSIRIS limb-radiance spectra is described. A forward model has been developed to simulate these spectra, and it consists of a single-scattering radiative-transfer model with partial spherical geometry, trace-gas absorption, Mic scattering by stratospheric aerosols, a Lambertian surface contribution, and OSIRIS instrument response and noise. Number-density profiles have been retrieved by using optimal estimation (OE) to combine an a priori profile with the information from sets of synthetic 'measurements'. For ozone, OE has been applied both to limb radiances at one or more discrete wavelengths and to effective-column abundances retrieved over a broad spectral range using differential optical absorption spectroscopy (DOAS). The results suggest that, between 15 and 35 km, ozone number densities can be retrieved to 10% accuracy or better on 1 and 2 km grids and to 5% on a 5 km grid. The combined DOAS-OE approach has also been used to retrieve NO 2 number densities, yielding 13% accuracy or better for altitudes from 18 to 36 km (in a 2 km grid. Differential optical absorption spectroscopy - optimal estimation retrievals of BrO and OC1O reproduce the true profiles above 15 km in the noise-free case, but the quality of the retrievals is highly sensitive to noise on the simulated OSIRIS spectra because of the weak absorption of these two gases. The development of inversion methods for the retrieval of trace-gas concentrations from OSIRIS spectra is continuing

Vertical profiles of nitrous acid in the nocturnal urban atmosphere of Houston, TX

Directory of Open Access Journals (Sweden)

K. W. Wong

2011-04-01

Full Text Available Nitrous acid (HONO often plays an important role in tropospheric photochemistry as a major precursor of the hydroxyl radical (OH in early morning hours and potentially during the day. However, the processes leading to formation of HONO and its vertical distribution at night, which can have a considerable impact on daytime ozone formation, are currently poorly characterized by observations and models. Long-path differential optical absorption spectroscopy (LP-DOAS measurements of HONO during the 2006 TexAQS II Radical and Aerosol Measurement Project (TRAMP, near downtown Houston, TX, show nocturnal vertical profiles of HONO, with mixing ratios of up to 2.2 ppb near the surface and below 100 ppt aloft. Three nighttime periods of HONO, NO₂ and O₃ observations during TRAMP were used to perform model simulations of vertical mixing ratio profiles. By adjusting vertical mixing and NO_x emissions the modeled NO₂ and O₃ mixing ratios showed very good agreement with the observations.

Using a simple conversion of NO₂ to HONO on the ground, direct HONO emissions, as well as HONO loss at the ground and on aerosol, the observed HONO profiles were reproduced by the model for 1–2 and 7–8 September in the nocturnal boundary layer (NBL. The unobserved increase of HONO to NO₂ ratio (HONO/NO₂ with altitude that was simulated by the initial model runs was found to be due to HONO uptake being too small on aerosol and too large on the ground. Refined model runs, with adjusted HONO uptake coefficients, showed much better agreement of HONO and HONO/NO₂ for two typical nights, except during morning rush hour, when other HONO formation pathways are most likely active. One of the nights analyzed showed an increase of HONO mixing ratios together with decreasing NO₂ mixing ratios that the model was unable to reproduce, most likely due to the impact of

Visualisation of air–water bubbly column flow using array Ultrasonic Velocity Profiler

Directory of Open Access Journals (Sweden)

Munkhbat Batsaikhan

2017-11-01

Full Text Available In the present work, an experimental study of bubbly two-phase flow in a rectangular bubble column was performed using two ultrasonic array sensors, which can measure the instantaneous velocity of gas bubbles on multiple measurement lines. After the sound pressure distribution of sensors had been evaluated with a needle hydrophone technique, the array sensors were applied to two-phase bubble column. To assess the accuracy of the measurement system with array sensors for one and two-dimensional velocity, a simultaneous measurement was performed with an optical measurement technique called particle image velocimetry (PIV. Experimental results showed that accuracy of the measurement system with array sensors is under 10% for one-dimensional velocity profile measurement compared with PIV technique. The accuracy of the system was estimated to be under 20% along the mean flow direction in the case of two-dimensional vector mapping.

A theory for natural convection turbulent boundary layers next to heated vertical surfaces

International Nuclear Information System (INIS)

George, W.K. Jr.; Capp, S.P.

1979-01-01

The turbulent natural convection boundary layer next to a heated vertical surface is analyzed by classical scaling arguments. It is shown that the fully developed turbulent boundary layer must be treated in two parts: and outer region consisting of most of the boundary layer in which viscous and conduction terms are negligible and an inner region in which the mean convection terms are negligible. The inner layer is identified as a constant heat flux layer. A similarity analysis yields universal profiles for velocity and temperature in the outer and constant heat flux layers. An asymptotic matching of these profiles in an intermediate layer (the buoyant sublayer) yields analytical expressions for the buoyant sublayer profiles. Asymptotic heat transfer and friction laws are obtained for the fully developed boundary layers. Finally, conductive and thermo-viscous sublayers characterized by a linear variation of velocity and temperature are shown to exist at the wall. All predictions are seen to be in excellent agreement with the abundant experimental data. (author)

Measurement of the dark matter velocity anisotropy profile in galaxy clusters

International Nuclear Information System (INIS)

Host, Ole

2009-01-01

Dark matter halos contribute the major part of the mass of galaxy clusters and the formation of these cosmological structures have been investigated in numerical simulations. Observations have been found to be in good agreement with the numerical predictions regarding the spatial distribution of dark matter, i.e. the mass profile. However, the dynamics of dark matter in halos has so far proved a greater challenge to probe observationally. We have used observations of 16 relaxed galaxy clusters to show that the dark matter velocity dispersion is larger along the radial direction than along the tangential, and that the magnitude of this velocity anisotropy β varies with radius. This measurement implies that the collective behaviour of dark matter particles is fundamentally different from that of baryonic particles and constrains the self-interaction per unit mass. The radial variation of the anisotropy velocity agrees with the predictions so that, on cluster scales, there is now excellent agreement between numerical predictions and observations regarding the phase space of dark matter.

Numerical performance analysis of acoustic Doppler velocity profilers in the wake of an axial-flow marine hydrokinetic turbine

Energy Technology Data Exchange (ETDEWEB)

Richmond, Marshall C.; Harding, Samuel F.; Romero Gomez, Pedro DJ

2015-09-01

The use of acoustic Doppler current profilers (ADCPs) for the characterization of flow conditions in the vicinity of both experimental and full scale marine hydrokinetic (MHK) turbines is becoming increasingly prevalent. The computation of a three dimensional velocity measurement from divergent acoustic beams requires the assumption that the flow conditions are homogeneous between all beams at a particular axial distance from the instrument. In the near wake of MHK devices, the mean fluid motion is observed to be highly spatially dependent as a result of torque generation and energy extraction. This paper examines the performance of ADCP measurements in such scenarios through the modelling of a virtual ADCP (VADCP) instrument in the velocity field in the wake of an MHK turbine resolved using unsteady computational fluid dynamics (CFD). This is achieved by sampling the CFD velocity field at equivalent locations to the sample bins of an ADCP and performing the coordinate transformation from beam coordinates to instrument coordinates and finally to global coordinates. The error in the mean velocity calculated by the VADCP relative to the reference velocity along the instrument axis is calculated for a range of instrument locations and orientations. The stream-wise velocity deficit and tangential swirl velocity caused by the rotor rotation lead to significant misrepresentation of the true flow velocity profiles by the VADCP, with the most significant errors in the transverse (cross-flow) velocity direction.

Reproducing {sup 137}Cs vertical migration in Spanish soils - Reproducing {sup 137}Cs and {sup 90}Sr vertical migration in Spanish mainland

Energy Technology Data Exchange (ETDEWEB)

Olondo, C.; Legarda, F.; Herranz, M.; Idoeta, R. [The University of the Basque Country - UPV/EHU, Nuclear Engineering and Fluid Mechanics Dept. Faculty of Engineering, Alda. Urquijo 48013, Bilbao (Spain)

2014-07-01

As a result of caesium's and strontium's activity migration study developed in Spanish mainland soils, there has been obtained convective - diffusive migration equation that will reproduce adequately the movement that an activity deposit would follow in this land. Taking into account the dependence on rain that apparent convection velocity shows, it has been defined a new migration parameter that depends only on soil's properties. By means of a least square method and fitting the migration equation to experimental activity profiles, the values showed by the migration parameters in the studied soils, characteristics of that area, have been obtained. After that, there have been obtained the mean values of these parameters for each defined group that, depending on soil's texture, have been observed in the study performed about the movement of both radionuclides in soils and to whom these soils belong. Using these mean values and obtained equation, it has been properly reproduce those vertical activity profiles that were experimentally determined. In order to validate these values, a new sampling programme is carrying out in the north of Spain and, with obtained new sampling points' information, is going to verify if, indeed, obtained mean values also reproduce these new sampling points' activity vertical profile. (authors)

Time-resolved wave-profile measurements at impact velocities of 10 km/s

Energy Technology Data Exchange (ETDEWEB)

Chhabildas, L.C.; Furnish, M.D.; Reinhart, W.D.

1998-06-01

Development of well-controlled hypervelocity launch capabilities is the first step to understand material behavior at extreme pressures and temperatures not available using conventional gun technology. In this paper, techniques used to extend both the launch capabilities of a two-stage light-gas gun to 10 km/s and their use to determine material properties at pressures and temperature states higher than those ever obtained in the laboratory are summarized. Time-resolved interferometric techniques have been used to determine shock loading and release characteristics of materials impacted by titanium and aluminum fliers launched by the only developed three-stage light-gas gun at 10 km/s. In particular, the Sandia three stage light gas gun, also referred to as the hypervelocity launcher, HVL, which is capable of launching 0.5 mm to 1.0 mm thick by 6 mm to 19 mm diameter plates to velocities approaching 16 km/s has been used to obtain the necessary impact velocities. The VISAR, interferometric particle-velocity techniques has been used to determine shock loading and release profiles in aluminum and titanium at impact velocities of 10 km/s.

Velocity Deficits in the Wake of Model Lemon Shark Dorsal Fins Measured with Particle Image Velocimetry

Science.gov (United States)

Terry, K. N.; Turner, V.; Hackett, E.

2017-12-01

Aquatic animals' morphology provides inspiration for human technological developments, as their bodies have evolved and become adapted for efficient swimming. Lemon sharks exhibit a uniquely large second dorsal fin that is nearly the same size as the first fin, the hydrodynamic role of which is unknown. This experimental study looks at the drag forces on a scale model of the Lemon shark's unique two-fin configuration in comparison to drag forces on a more typical one-fin configuration. The experiments were performed in a recirculating water flume, where the wakes behind the scale models are measured using particle image velocimetry. The experiments are performed at three different flow speeds for both fin configurations. The measured instantaneous 2D distributions of the streamwise and wall-normal velocity components are ensemble averaged to generate streamwise velocity vertical profiles. In addition, velocity deficit profiles are computed from the difference between these mean streamwise velocity profiles and the free stream velocity, which is computed based on measured flow rates during the experiments. Results show that the mean velocities behind the fin and near the fin tip are smallest and increase as the streamwise distance from the fin tip increases. The magnitude of velocity deficits increases with increasing flow speed for both fin configurations, but at all flow speeds, the two-fin configurations generate larger velocity deficits than the one-fin configurations. Because the velocity deficit is directly proportional to the drag force, these results suggest that the two-fin configuration produces more drag.

Vertical Transport of Momentum by the Inertial-Gravity Internal Waves in a Baroclinic Current

Directory of Open Access Journals (Sweden)

A. A. Slepyshev

2017-08-01

Full Text Available When the internal waves break, they are one of the sources of small-scale turbulence. Small-scale turbulence causes the vertical exchange in the ocean. However, internal waves with regard to the Earth rotation in the presence of vertically inhomogeneous two-dimensional current are able to contribute to the vertical transport. Free inertial-gravity internal waves in a baroclinic current in a boundless basin of a constant depth are considered in the Bussinesq approximation. Boundary value problem of linear approximation for the vertical velocity amplitude of internal waves has complex coefficients when current velocity component, which is transversal to the wave propagation direction, depends on the vertical coordinate (taking into account the rotation of the Earth. Eigenfunction and wave frequency are complex, and it is shown that a weak wave damping takes place. Dispersive relation and wave damping decrement are calculated in the linear approximation. At a fixed wave number damping decrement of the second mode is larger (in the absolute value than the one of the first mode. The equation for vertical velocity amplitude for real profiles of the Brunt – Vaisala frequency and current velocity are numerically solved according to implicit Adams scheme of the third order of accuracy. The dispersive curves of the first two modes do not reach inertial frequency in the low-frequency area due to the effect of critical layers in which wave frequency of the Doppler shift is equal to the inertial one. Termination of the second mode dispersive curves takes place at higher frequency than the one of the first mode. In the second order of the wave amplitude the Stokes drift speed is determined. It is shown that the Stokes drift speed, which is transversal to the wave propagation direction, differs from zero if the transversal component of current velocity depends on the vertical coordinate. In this case, the Stokes drift speed in the second mode is lower than

A method of solution for the determination of the velocity profiles in turbulent flow through annular tobes

International Nuclear Information System (INIS)

Schmal, M.; Russo, Q.; Almeida, M.S.; Bozzo, S.

1975-01-01

A method of solutions is presented for the determination of the velocity profiles in turbulent flow through annular tubes, based on the Von Karman similarity theory developed by Quarmby. The parameters found by Quarmby appearing in the velocity profiles and determined experimentally by different authors were approximated by polynonial functions of variable degree, as function of the Reynolds numbers. The Runge-Kutta-Nystrom method was used in the integration of the differential equations and the systematic of solution is presented in a computer program. The calculated results were compared to the experimental date and presented a deviation of 10 -2 % [pt

Ultrasound propagation in steel piping at electric power plant using clamp-on ultrasonic pulse doppler velocity-profile flowmeter

International Nuclear Information System (INIS)

Tezuka, Kenichi; Mori, Michitsugu; Wada, Sanehiro; Aritomi, Masanori; Kikura, Hiroshige

2008-01-01

Venturi nozzles are widely used to measure the flow rates of reactor feedwater. This flow rate of nuclear reactor feedwater is an important factor in the operation of nuclear power reactors. Some other types of flowmeters have been proposed to improve measurement accuracy. The ultrasonic pulse Doppler velocity-profile flowmeter is expected to be a candidate method because it can measure the flow profiles across the pipe cross sections. For the accurate estimation of the flow velocity, the incidence angle of ultrasonic entering the fluid should be carefully estimated by the theoretical approach. However, the evaluation of the ultrasound propagation is not straightforward for the several reasons such as temperature gradient in the wedge or mode conversion at the interface between the wedge and pipe. In recent years, the simulation code for ultrasound propagation has come into use in the nuclear field for nondestructive testing. This article analyzes and discusses ultrasound propagation in steel piping and water, using the 3D-FEM simulation code and the Kirchhoff method, as it relates to the flow profile measurements in power plants with the ultrasonic pulse Doppler velocity-profile flowmeter. (author)

Monte Carlo-based subgrid parameterization of vertical velocity and stratiform cloud microphysics in ECHAM5.5-HAM2

Directory of Open Access Journals (Sweden)

J. Tonttila

2013-08-01

Full Text Available A new method for parameterizing the subgrid variations of vertical velocity and cloud droplet number concentration (CDNC is presented for general circulation models (GCMs. These parameterizations build on top of existing parameterizations that create stochastic subgrid cloud columns inside the GCM grid cells, which can be employed by the Monte Carlo independent column approximation approach for radiative transfer. The new model version adds a description for vertical velocity in individual subgrid columns, which can be used to compute cloud activation and the subgrid distribution of the number of cloud droplets explicitly. Autoconversion is also treated explicitly in the subcolumn space. This provides a consistent way of simulating the cloud radiative effects with two-moment cloud microphysical properties defined at subgrid scale. The primary impact of the new parameterizations is to decrease the CDNC over polluted continents, while over the oceans the impact is smaller. Moreover, the lower CDNC induces a stronger autoconversion of cloud water to rain. The strongest reduction in CDNC and cloud water content over the continental areas promotes weaker shortwave cloud radiative effects (SW CREs even after retuning the model. However, compared to the reference simulation, a slightly stronger SW CRE is seen e.g. over mid-latitude oceans, where CDNC remains similar to the reference simulation, and the in-cloud liquid water content is slightly increased after retuning the model.

Ultrasonic Doppler Velocity Profiler for Fluid Flow

CERN Document Server

2012-01-01

The ultrasonic velocity profile (UVP) method, first developed in medical engineering, is now widely used in clinical settings. The fluid mechanical basis of UVP was established in investigations by the author and his colleagues with work demonstrating that UVP is a powerful new tool in experimental fluid mechanics. There are diverse examples, ranging from problems in fundamental fluid dynamics to applied problems in mechanical, chemical, nuclear, and environmental engineering. In all these problems, the methodological principle in fluid mechanics was converted from point measurements to spatio-temporal measurements along a line. This book is the first monograph on UVP that offers comprehensive information about the method, its principles, its practice, and applied examples, and which serves both current and new users. Current users can confirm that their application configurations are correct, which will help them to improve the configurations so as to make them more efficient and effective. New users will be...

The hydraulic diffusivity and conductivity determination of structured purple soil and purple latosol by vertical infiltration

International Nuclear Information System (INIS)

Appoloni, C.R.; Souza, A.D.B. de; Fante Junior, L.; Oliveira Junior, J.M. de; Oliveira, J.C.M. de.

1990-01-01

The hydraulic diffusivity and conductivity functions of LR (purple latosol) and TE (structured purple soil) (levels A and B) soil samples from the Londrina-PR region were calculated by means of the moisture profile and data from the time evolution of the wet front, taken through measurements of the water infiltration in a soil column and a variational of the vertical flow. The wet front data were taken in a acrylic column coupled in bits base with a porous plate that permitted the water flow against the gravitational field with a suitable velocity of 0.12 cm/min. The moisture profile data were obtained by the gamma ray attenuation method, with a 60 Co source and a Na I (TL) scintillation detector. With a vertical and horizontal measurement table the moisture profile data θ (z,t) were taken in many points of the soil column. (author)

Two-dimensional, average velocity field across the Asal Rift, Djibouti from 1997-2008 RADARSAT data

Science.gov (United States)

Tomic, J.; Doubre, C.; Peltzer, G.

2009-12-01

Located at the western end of the Aden ridge, the Asal Rift is the first emerged section of the ridge propagating into Afar, a region of intense volcanic and tectonic activity. We construct a two-dimensional surface velocity map of the 200x400 km2 region covering the rift using the 1997-2008 archive of InSAR data acquired from ascending and descending passes of the RADARSAT satellite. The large phase signal due to turbulent troposphere conditions over the Afar region is mostly removed from the 11-year average line of sight (LOS) velocity maps, revealing a clear deformation signal across the rift. We combine the ascending and descending pass LOS velocity fields with the Arabia-Somalia pole of rotation adjusted to regional GPS velocities (Vigny et al., 2007) to compute the fields of the vertical and horizontal, GPS-parallel components of the velocity over the rift. The vertical velocity field shows a ~40 km wide zone of doming centered over the Fieale caldera associated with shoulder uplift and subsidence of the rift inner floor. Differential movement between shoulders and floor is accommodated by creep at 6 mm/yr on Fault γ and 2.7 mm/yr on Fault E. The horizontal field shows that the two shoulders open at a rate of ~15 mm/yr, while the horizontal velocity decreases away from the rift to the plate motion rate of ~11 mm/yr. Part of the opening is concentrated on faults γ (5 mm/yr) and E (4 mm/yr) and about 4 mm/yr is distributed between Fault E and Fault H in the southern part of the rift. The observed velocity field along a 60 km-long profile across the eastern part of the rift can be explained with a 2D mechanical model involving a 5-9 km-deep, vertical dyke expanding horizontally at a rate of 5 cm/yr, a 2 km-wide, 7 km-deep sill expanding vertically at 1cm/yr, and down-dip and opening of faults γ and E. Results from 3D rift models describing along-strike velocity decrease away from the Goubbet Gulf and the effects of a pressurized magma chamber will be

Relation of Cloud Occurrence Frequency, Overlap, and Effective Thickness Derived from CALIPSO and CloudSat Merged Cloud Vertical Profiles

Science.gov (United States)

Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

2009-01-01

A cloud frequency of occurrence matrix is generated using merged cloud vertical profile derived from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR). The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical pro les can be related by a set of equations when the correlation distance of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches the random overlap with increasing distance separating cloud layers and that the probability of deviating from the random overlap decreases exponentially with distance. One month of CALIPSO and CloudSat data support these assumptions. However, the correlation distance sometimes becomes large, which might be an indication of precipitation. The cloud correlation distance is equivalent to the de-correlation distance introduced by Hogan and Illingworth [2000] when cloud fractions of both layers in a two-cloud layer system are the same.

Examples of invasive and non-invasive methods for estimation of shear-wave velocity profile in Bucharest

International Nuclear Information System (INIS)

Aldea, A.; Albota, E.; Yamanaka, H.; Fukumoto, S.; Poiata, N.

2007-01-01

The estimation of subsurface shear-wave velocity is of major importance for understanding and modelling site-response and surface ground motion. The shear-wave velocity profile strongly influence the shear-wave part of the seismic motion that proved to be the most damaging one. The improvement of input seismic ground motion for design is one of the long-term objectives within the Japan International Cooperation Agency (JICA) Project in Romania. Two approaches were used: installation of a digital seismic network and soil investigations (in situ and in laboratory). National Center for Seismic Risk Reduction (NCSRR, Romania), the implementing agency of JICA Project, performed these activities in cooperation with Japanese partner institutions, and an efficient know-how transfer was achieved. Between the soil investigation activities, a special importance was given to the estimation of shear-wave velocity profile. The present paper presents results from PS logging tests at NCSRR seismic station sites, and from single-station and array microtremor measurements. Other results from PS logging tests, surface-wave method and in situ and laboratory geotechnical investigations are presented in other papers in these proceedings. In future, a joint-collaborative effort of Romanian institutions may allow an improved characterisation of the soil profile beneath Bucharest. (authors)

Dependence of energy characteristics of ascending swirling air flow on velocity of vertical blowing

Science.gov (United States)

Volkov, R. E.; Obukhov, A. G.; Kutrunov, V. N.

2018-05-01

In the model of a compressible continuous medium, for the complete Navier-Stokes system of equations, an initial boundary problem is proposed that corresponds to the conducted and planned experiments and describes complex three-dimensional flows of a viscous compressible heat-conducting gas in ascending swirling flows that are initiated by a vertical cold blowing. Using parallelization methods, three-dimensional nonstationary flows of a polytropic viscous compressible heat-conducting gas are constructed numerically in different scaled ascending swirling flows under the condition when gravity and Coriolis forces act. With the help of explicit difference schemes and the proposed initial boundary conditions, approximate solutions of the complete system of Navier-Stokes equations are constructed as well as the velocity and energy characteristics of three-dimensional nonstationary gas flows in ascending swirling flows are determined.

Skeleton sled velocity profiles: a novel approach to understand critical aspects of the elite athletes' start phases.

Science.gov (United States)

Colyer, Steffi L; Stokes, Keith A; Bilzon, James L J; Salo, Aki I T

2018-06-01

The development of velocity across the skeleton start is critical to performance, yet poorly understood. We aimed to understand which components of the sled velocity profile determine performance and how physical abilities influence these components. Thirteen well-trained skeleton athletes (>85% of athletes in the country) performed dry-land push-starts alongside countermovement jump and sprint tests at multiple time-points. A magnet encoder attached to the sled wheel provided velocity profiles, which were characterised using novel performance descriptors. Stepwise regression revealed four variables (pre-load velocity, pre-load distance, load effectiveness, velocity drop) to explain 99% variance in performance (β weights: 1.70, -0.81, 0.25, -0.07, respectively). Sprint times and jump ability were associated (r ± 90% CI) with pre-load velocity (-0.70 ± 0.27 and 0.88 ± 0.14, respectively) and distance (-0.48 ± 0.39 and 0.67 ± 0.29, respectively), however, unclear relationships between both physical measures and load effectiveness (0.33 ± 0.44 and -0.35 ± 0.48, respectively) were observed. Athletes should develop accelerative ability to attain higher velocity earlier on the track. Additionally, the loading phase should not be overlooked and may be more influenced by technique than physical factors. Future studies should utilise this novel approach when evaluating skeleton starts or interventions to enhance performance.

A catalogue of masses, structural parameters and velocity dispersion profiles of 112 Milky Way globular clusters

Science.gov (United States)

Baumgardt, H.; Hilker, M.

2018-05-01

We have determined masses, stellar mass functions and structural parameters of 112 Milky Way globular clusters by fitting a large set of N-body simulations to their velocity dispersion and surface density profiles. The velocity dispersion profiles were calculated based on a combination of more than 15,000 high-precision radial velocities which we derived from archival ESO/VLT and Keck spectra together with ˜20, 000 published radial velocities from the literature. Our fits also include the stellar mass functions of the globular clusters, which are available for 47 clusters in our sample, allowing us to self-consistently take the effects of mass segregation and ongoing cluster dissolution into account. We confirm the strong correlation between the global mass functions of globular clusters and their relaxation times recently found by Sollima & Baumgardt (2017). We also find a correlation of the escape velocity from the centre of a globular cluster and the fraction of first generation stars (FG) in the cluster recently derived for 57 globular clusters by Milone et al. (2017), but no correlation between the FG star fraction and the global mass function of a globular cluster. This could indicate that the ability of a globular cluster to keep the wind ejecta from the polluting star(s) is the crucial parameter determining the presence and fraction of second generation stars and not its later dynamical mass loss.

Gas-liquid flow around an obstacle in a vertical pipe

International Nuclear Information System (INIS)

Prasser, Horst-Michael; Beyer, Matthias; Frank, Thomas; Al Issa, Suleiman; Carl, Helmar; Pietruske, Heiko; Schuetz, Peter

2008-01-01

This paper presents a novel technique to study the two-phase flow field around an asymmetric obstruction in a vertical pipe with a nominal diameter of DN200. Main feature of the experiments is the shifting of a half-moon shaped diaphragm causing the obstruction along the axis of the pipe. In this way, the 3D void field is scanned with a stationary wire-mesh sensor that supplies data with a spatial resolution of 3 mm over the cross-section and a measuring frequency of 2.5 kHz. Besides the measurement of time-averaged void fraction fields and bubble-size distributions, novel data evaluation methods were developed to extract estimated liquid velocity profiles as well as lateral components of bubble velocities from the wire-mesh sensor data. The combination of void fraction fields and velocity profiles offer the opportunity to analyse a two-phase flow in a geometry that owns a series of features characteristic for complex components of power and chemical plant equipment. Such characteristics are sharp edges with flow separation, recirculation areas, jet formation, stagnation points and curved stream-lines. The tests were performed with an air-water flow at nearly ambient conditions and with a saturated steam-water mixture at 6.5 MPa. The superficial velocities of liquid and gas or, respectively, vapour were varied in a wide range. The flow structure upstream and downstream of the obstacle is characterized in detail. Bubble size dependent effects of bubble accumulation and migration are discussed on basis of void-fraction profiles decomposed into bubble-size classes. A pronounced influence of the fluid parameters was found in the behaviour of bubbles at the boundary of the jet coming from the non-obstructed part of the cross-section. In case of an air-water flow, bubbles are restrained from entering the jet, a phenomenon which was not observed in high-pressure steam-water flow. A detailed uncertainty analyse of the velocity assessments finishes the presented paper. A

Depth-dependence of time-lapse seismic velocity change detected by a joint interferometric analysis of vertical array data

Science.gov (United States)

Sawazaki, K.; Saito, T.; Ueno, T.; Shiomi, K.

2015-12-01

In this study, utilizing depth-sensitivity of interferometric waveforms recorded by co-located Hi-net and KiK-net sensors, we separate the responsible depth of seismic velocity change associated with the M6.3 earthquake occurred on November 22, 2014, in central Japan. The Hi-net station N.MKGH is located about 20 km northeast from the epicenter, where the seismometer is installed at the 150 m depth. At the same site, the KiK-net has two strong motion seismometers installed at the depths of 0 and 150 m. To estimate average velocity change around the N.MKGH station, we apply the stretching technique to auto-correlation function (ACF) of ambient noise recorded by the Hi-net sensor. To evaluate sensitivity of the Hi-net ACF to velocity change above and below the 150 m depth, we perform a numerical wave propagation simulation using 2-D FDM. To obtain velocity change above the 150 m depth, we measure response waveform from the depths of 150 m to 0 m by computing deconvolution function (DCF) of earthquake records obtained by the two KiK-net vertical array sensors. The background annual velocity variation is subtracted from the detected velocity change. From the KiK-net DCF records, the velocity reduction ratio above the 150 m depth is estimated to be 4.2 % and 3.1 % in the periods of 1-7 days and 7 days - 4 months after the mainshock, respectively. From the Hi-net ACF records, the velocity reduction ratio is estimated to be 2.2 % and 1.8 % in the same time periods, respectively. This difference in the estimated velocity reduction ratio is attributed to depth-dependence of the velocity change. By using the depth sensitivity obtained from the numerical simulation, we estimate the velocity reduction ratio below the 150 m depth to be lower than 1.0 % for both time periods. Thus the significant velocity reduction and recovery are observed above the 150 m depth only, which may be caused by strong ground motion of the mainshock and following healing in the shallow ground.

One Year of Vertical Wind Profiles Measurements at a Mediterranean Coastal Site of South Italy

DEFF Research Database (Denmark)

Calidonna, Claudia Roberta; Gullì, Daniel; Avolio, Elenio

2015-01-01

To exploit wind energy both onshore and offshore in coastal area the effect of the coastal discontinuity is important. The shape of the vertical wind profiles and the related c parameter of the Weibull distribution are impacted by the atmospheric internal boundary layers developing from the coast...

Constitutive Curve and Velocity Profile in Entangled Polymers during Start-Up of Steady Shear Flow

KAUST Repository

Hayes, Keesha A.; Buckley, Mark R.; Qi, Haibo; Cohen, Itai; Archer, Lynden A.

2010-01-01

-4]. Surprisingly, we find that even polymer systems which exhibit transient, nonmonotonic shear stress-shear rate relationships in bulk rheology experiments manifest time-dependent velocity profiles that are decidedly linear and show no evidence of unstable flow

Validation of vertical profile from atmosphere using ATOVS products and its impact over Indian region.

Science.gov (United States)

Mahandru, Riddhi; Kumar, Adarsh; Mitra, Ashim kumar

This research paper summarizes the validation of atmospheric vertical profile using NOAA(National Oceanic and Atmospheric Administration)/ MetOp satellite derived data over India with radiosonde observations over a span of 8 months. NOAA's International Advanced Television and Infrared Observations satellite Vertical Sounder (ATOVS) processing package (IAPP) obtains temperature and moisture profiles in different pressure levels ranging from 1000hpa to 10hpa from real time direct broadcast (DB) receiving system installed at India Meteorological department. Different pressure levels were substituted to the same pressure levels for calculations of standard deviation, bias and RMSE (root mean square error) The sounder derived products like Total precipitable water vapor (TPW) and Lifting index(LI) from NOAA Satellite was also validated with radiosonde data which provided significant results for weather forecasting. The validation shows that the sounder provides unique information about the state of atmosphere and monitoring the convective environment for severe weather forecasting In addition to this, case study on severe weather events was analyzed using ATOVS products.

Coding of Velocity Storage in the Vestibular Nuclei

Directory of Open Access Journals (Sweden)

Sergei B. Yakushin

2017-08-01

Full Text Available Semicircular canal afferents sense angular acceleration and output angular velocity with a short time constant of ≈4.5 s. This output is prolonged by a central integrative network, velocity storage that lengthens the time constants of eye velocity. This mechanism utilizes canal, otolith, and visual (optokinetic information to align the axis of eye velocity toward the spatial vertical when head orientation is off-vertical axis. Previous studies indicated that vestibular-only (VO and vestibular-pause-saccade (VPS neurons located in the medial and superior vestibular nucleus could code all aspects of velocity storage. A recently developed technique enabled prolonged recording while animals were rotated and received optokinetic stimulation about a spatial vertical axis while upright, side-down, prone, and supine. Firing rates of 33 VO and 8 VPS neurons were studied in alert cynomolgus monkeys. Majority VO neurons were closely correlated with the horizontal component of velocity storage in head coordinates, regardless of head orientation in space. Approximately, half of all tested neurons (46% code horizontal component of velocity in head coordinates, while the other half (54% changed their firing rates as the head was oriented relative to the spatial vertical, coding the horizontal component of eye velocity in spatial coordinates. Some VO neurons only coded the cross-coupled pitch or roll components that move the axis of eye rotation toward the spatial vertical. Sixty-five percent of these VO and VPS neurons were more sensitive to rotation in one direction (predominantly contralateral, providing directional orientation for the subset of VO neurons on either side of the brainstem. This indicates that the three-dimensional velocity storage integrator is composed of directional subsets of neurons that are likely to be the bases for the spatial characteristics of velocity storage. Most VPS neurons ceased firing during drowsiness, but the firing

Numerical and experimental analysis of vertical spray control patternators

Directory of Open Access Journals (Sweden)

F. Sarghini

2013-09-01

Full Text Available The experimental vertical spray control walls have the purpose of picking up the liquid delivered by trained sprayer for providing the liquid distribution profile in height. Theoretically this should correspond to the ideal profile, which consists in a uniform distribution on the vegetation. If the profile is different from the ideal, a parameter setup is required on the sprayer. Nonetheless, some problems are hidden in the aforementioned statements: i no wall measures exactly the distribution profile (i.e. the flow through the sections in the vertical plane, parallel to the direction of advancement of the sprayer. Compared to real profile, sensitive errors are introduced: the evaporation of the drops, the deviation of the air flows caused by the sensors panel themselves; by the possibility that the drops bounce on the wall panels, also due to the current of air that can push the liquid veil laterally or upwards, Moreover, everything varies depending on the geometry of the sensors, air velocity, air humidity; ii no one knows what exactly is the optimal distribution profile. It is often considered as optimal a profile that reflects the amount of leaf area subtended by each section absorber: however, it is evident that the path of the droplets changes according to the sprayer typology (eg. radial-flow or horizontal flows. In this work a combined numerical-experimental approach is adopted, in order to assess some of the aforementioned issues: numerical data obtained by using computational fluid dynamics models are compared and validated with experimental data, in order to assess the reliability of numerical simulations in configurations which are difficult to analyze using an experimental setup.

Quantitative precipitation estimation in complex orography using quasi-vertical profiles of dual polarization radar variables

Science.gov (United States)

Montopoli, Mario; Roberto, Nicoletta; Adirosi, Elisa; Gorgucci, Eugenio; Baldini, Luca

2017-04-01

Weather radars are nowadays a unique tool to estimate quantitatively the rain precipitation near the surface. This is an important task for a plenty of applications. For example, to feed hydrological models, mitigate the impact of severe storms at the ground using radar information in modern warning tools as well as aid the validation studies of satellite-based rain products. With respect to the latter application, several ground validation studies of the Global Precipitation Mission (GPM) products have recently highlighted the importance of accurate QPE from ground-based weather radars. To date, a plenty of works analyzed the performance of various QPE algorithms making use of actual and synthetic experiments, possibly trained by measurement of particle size distributions and electromagnetic models. Most of these studies support the use of dual polarization variables not only to ensure a good level of radar data quality but also as a direct input in the rain estimation equations. Among others, one of the most important limiting factors in radar QPE accuracy is the vertical variability of particle size distribution that affects at different levels, all the radar variables acquired as well as rain rates. This is particularly impactful in mountainous areas where the altitudes of the radar sampling is likely several hundred of meters above the surface. In this work, we analyze the impact of the vertical profile variations of rain precipitation on several dual polarization radar QPE algorithms when they are tested a in complex orography scenario. So far, in weather radar studies, more emphasis has been given to the extrapolation strategies that make use of the signature of the vertical profiles in terms of radar co-polar reflectivity. This may limit the use of the radar vertical profiles when dual polarization QPE algorithms are considered because in that case all the radar variables used in the rain estimation process should be consistently extrapolated at the surface

Daytime, low latitude, vertical ExB drift velocities, inferred from ground-based magnetometer observations in the Peruvian, Philippine and Indian longitude sectors under quiet and disturbed conditions

CERN Document Server

Anderson, D; Chau, J; Yumoto, K; Bhattacharya, A; Alex, S

2006-01-01

Daytime, low latitude, vertical ExB drift velocities, inferred from ground-based magnetometer observations in the Peruvian, Philippine and Indian longitude sectors under quiet and disturbed conditions

Lorentz force effect on mixed convection micropolar flow in a vertical conduit

Science.gov (United States)

Abdel-wahed, Mohamed S.

2017-05-01

The present work provides a simulation of control and filtration process of hydromagnetic blood flow with Hall current under the effect of heat source or sink through a vertical conduit (pipe). This work meets other engineering applications, such as nuclear reactors cooled during emergency shutdown, geophysical transport in electrically conducting and heat exchangers at low velocity conditions. The problem is modeled by a system of partial differential equations taking the effect of viscous dissipation, and these equations are simplified and solved analytically as a series solution using the Differential Transformation Method (DTM). The velocities and temperature profiles of the flow are plotted and discussed. Moreover, the conduit wall shear stress and heat flux are deduced and explained.

Turbulent structure of thermal plume. Velocity field

International Nuclear Information System (INIS)

Guillou, B.; Brahimi, M.; Doan-kim-son

1986-01-01

An experimental investigation and a numerical study of the dynamics of a turbulent plume rising from a strongly heated source are described. This type of flow is met in thermal effluents (air, vapor) from, e.g., cooling towers of thermal power plants. The mean and fluctuating values of the vertical component of the velocity were determined using a Laser-Doppler anemometer. The measurements allow us to distinguish three regions in the plume-a developing region near the source, an intermediate region, and a self-preserving region. The characteristics of each zone have been determined. In the self-preserving zone, especially, the turbulence level on the axis and the entrainment coefficient are almost twice of the values observed in jets. The numerical model proposed takes into account an important phenomenon, the intermittency, observed in the plume. This model, established with the self-preserving hypothesis, brings out analytical laws. These laws and the predicted velocity profile are in agreement with the experimental evolutions [fr

Investigation for vertical, two-phase steam-water flow of three turbine models

International Nuclear Information System (INIS)

Silverman, S.; Goodrich, L.D.

1977-01-01

One of the basic quantities of interest during a loss-of-coolant experiment (LOCE) is the primary system mass flow rate. Presently, there are no transducers commercially available which continuously measure this parameter. Therefore, a transducer was designed at EG and G Idaho, Inc. which combines a drag-disc and turbine into a single unit. The basis for the design was that the drag-disc would measure momentum flux (rhoV 2 ), the turbine would measure velocity and the mass flow rate could then be calculated from the two quantities by assuming a flow profile. For two-phase flow, the outputs are approximately proportional to the desired parameter, but rather large errors can be expected under those assumptions. Preliminary evaluation of the experimental two- and single-phase calibration data has resulted in uncertainty estimates of +-8% of range for the turbine and +-20% of range for the drag-disc. In an effort to reduce the errors, further investigations were made to determine what the drag-disc and turbine really measure. In the present paper, three turbine models for vertical, two-phase, steam/water flow are investigated; the Aya Model, the Rouhani Model, and a volumetric flow model. Theoretical predictions are compared with experimental data for vertical, two-phase steam/water flow. For the purposes of the mass flow calculation, velocity profiles were assumed to be flat for the free-field condition. It is appreciated that this may not be true for all cases investigated, but for an initial inspection, flat profiles were assumed

On Active Current Selection for Lagrangian Profilers

Directory of Open Access Journals (Sweden)

J. Jouffroy

2013-01-01

Full Text Available Autonomous Lagrangian profilers are now widely used as measurement and monitoring platforms, notably in observation programs as Argo. In a typical mode of operation, the profilers drift passively at their parking depthbefore making a vertical profile to go back to the surface. This paperpresents simple and computationally-efficient control strategies to activelyselect and use ocean currents so that a profiler can autonomously reach adesired destination. After briefly presenting a typical profiler andpossible mechanical modifications for a coastal environment, we introducesimple mathematical models for the profiler and the currents it will use. Wethen present simple feedback controllers that, using the direction of thecurrents and taking into account the configuration of the environment(coastal or deep-sea, is able to steer the profiler to any desiredhorizontal location. To illustrate the approach, a few results are presentedusing both simulated currents and real current velocity profiles from theNorth Sea.

ACTRIS aerosol vertical profile data and observations: potentiality and first examples of integrated studies with models

Science.gov (United States)

Mona, Lucia; Benedetti, Angela; D'Amico, Giuseppe; Myhre, Cathrine Lund; Schulz, Michael; Wandinger, Ulla; Laj, Paolo; Pappalardo, Gelsomina

2016-04-01

The ACTRIS-2 project, funded by Horizon 2020, addresses the scope of integrating state-of-the-art European ground-based stations for long term observations of aerosols, clouds and short lived gases, capitalizing on the work of FP7-ACTRIS. It aims at achieving the construction of a user-oriented RI, unique in the EU-RI landscape for providing 4-D integrated high-quality data from near-surface to high altitude (vertical profiles and total-column) which are relevant to climate and air-quality research. ACTRIS-2 develops and implements, in a large network of stations in Europe and beyond, observational protocols that permit the harmonization of collected data and their dissemination. ACTRIS secures provision and dissemination of a unique set of data and data-products that would not otherwise be available with the same level of quality and standardization. This results from a 10-year plus effort in constructing a research infrastructure capable of responding to community needs and requirements, and has been engaged since the start of the FP5 EU commission program. ACTRIS ensures compliance with reporting requirements (timing, format, traceability) defined by the major global observing networks. EARLINET (European Aerosol research Lidar NETwork), the aerosol vertical profiling component of ACTRIS, is providing since May 2000 vertical profiles of aerosol extinction and backscatter over Europe. A new structure of the EARLINET database has been designed in a more user oriented approach reporting new data products which are more effective for specific uses of different communities. In particular, a new era is starting with the Copernicus program during which the aerosol vertical profiling capability will be fundamental for assimilation and validation purposes. The new data products have been designed thanks to a strong link with EARLINET data users, first of all modeling and satellite communities, established since the beginning of EARLINET and re-enforced within ACTRIS2

Constraining the 0-20 km Vertical Profile of Water Vapor in the Martian Atmosphere with MGS-TES Limb Sounding

Science.gov (United States)

McConnochie, T. H.; Smith, M. D.; McDonald, G. D.

2016-12-01

The vertical profile of water vapor in the lower atmosphere of Mars is a crucial but poorly-measured detail of the water cycle. Most of our existing water vapor data sets (e.g. Smith, 2002, JGR 107; Smith et al., 2009, JGR 114; Maltagliati et al., 2011, Icarus 213) rely on the traditional assumption of uniform mass mixing from the surface up to a saturation level, but GCM models (Richardson et al., 2002, JGR 107; Navarro et al., 2014, JGR 119) imply that this is not the case in at least some important seasons and locations. For example at the equator during northern summer the water vapor mixing ratio in aforementioned GCMs increases upwards by a factor of two to three in the bottom scale height. This might influence the accuracy of existing precipitable water column (PWC) data sets. Even if not, the correct vertical distribution is critical for determining the extent to which high-altitude cold trapping interferes with inter-hemispheric transport, and its details in the lowest scale heights will be a critical test of the accuracy of modeled water vapor transport. Meanwhile attempts to understand apparent interactions of water vapor with surface soils (e.g. Ojha et al. 2015, Nature Geoscience 8; Savijärvi et al., 2016, Icarus 265) need an estimate for the amount of water vapor in the boundary layer, and existing PWC data sets can't provide this unless the lower atmospheric vertical distribution is known or constrained. Maltagliati et al. (2013, Icarus 223) have obtained vertical profiles of water vapor at higher altitudes with SPICAM on Mars Express, but these are commonly limited to altitudes greater 20 km and they never extend below 10 km. We have previously used Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) limb-sounding to measure the vertical profile of water vapor (e.g. McConnochie and Smith, 2009, Fall AGU #P54B-06), but these preliminary results were clearly not quantitatively accurate in the lower atmosphere. We will present improved TES

EFFECTS OF NITROGEN PHOTOABSORPTION CROSS SECTION RESOLUTION ON MINOR SPECIES VERTICAL PROFILES IN TITAN’S UPPER ATMOSPHERE

International Nuclear Information System (INIS)

Luspay-Kuti, A.; Mandt, K. E.; Greathouse, T. K.; Plessis, S.

2015-01-01

The significant variations in both measured and modeled densities of minor species in Titan’s atmosphere call for the evaluation of possible influencing factors in photochemical modeling. The effect of nitrogen photoabsorption cross section selection on the modeled vertical profiles of minor species is analyzed here, with particular focus on C 2 H 6 and HCN. Our results show a clear impact of cross sections used on all neutral and ion species studied. Affected species include neutrals and ions that are not primary photochemical products, including species that do not even contain nitrogen. The results indicate that photochemical models that employ low-resolution cross sections may significantly miscalculate the vertical profiles of minor species. Such differences are expected to have important implications for Titan’s overall atmospheric structure and chemistry

EFFECTS OF NITROGEN PHOTOABSORPTION CROSS SECTION RESOLUTION ON MINOR SPECIES VERTICAL PROFILES IN TITAN’S UPPER ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Luspay-Kuti, A.; Mandt, K. E.; Greathouse, T. K. [Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Plessis, S., E-mail: aluspaykuti@swri.edu [ICES, The University of Texas at Austin, 201 East 24th Street, Austin, TX 78712 (United States)

2015-03-01

The significant variations in both measured and modeled densities of minor species in Titan’s atmosphere call for the evaluation of possible influencing factors in photochemical modeling. The effect of nitrogen photoabsorption cross section selection on the modeled vertical profiles of minor species is analyzed here, with particular focus on C{sub 2}H{sub 6} and HCN. Our results show a clear impact of cross sections used on all neutral and ion species studied. Affected species include neutrals and ions that are not primary photochemical products, including species that do not even contain nitrogen. The results indicate that photochemical models that employ low-resolution cross sections may significantly miscalculate the vertical profiles of minor species. Such differences are expected to have important implications for Titan’s overall atmospheric structure and chemistry.

Vertical profiles of aerosol and black carbon in the Arctic: a seasonal phenomenology along 2 years (2011–2012 of field campaigns

Directory of Open Access Journals (Sweden)

L. Ferrero

2016-10-01

Full Text Available We present results from a systematic study of vertical profiles of aerosol number size distribution and black carbon (BC concentrations conducted in the Arctic, over Ny-Ålesund (Svalbard. The campaign lasted 2 years (2011–2012 and resulted in 200 vertical profiles measured by means of a tethered balloon (up to 1200 m a.g.l. during the spring and summer seasons. In addition, chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. The collected experimental data allowed a classification of the vertical profiles into different typologies, which allowed us to describe the seasonal phenomenology of vertical aerosol properties in the Arctic. During spring, four main types of profiles were found and their behavior was related to the main aerosol and atmospheric dynamics occurring at the measuring site. Background conditions generated homogenous profiles. Transport events caused an increase of aerosol concentration with altitude. High Arctic haze pollution trapped below thermal inversions promoted a decrease of aerosol concentration with altitude. Finally, ground-based plumes of locally formed secondary aerosol determined profiles with decreasing aerosol concentration located at different altitude as a function of size. During the summer season, the impact from shipping caused aerosol and BC pollution plumes to be constrained close to the ground, indicating that increasing shipping emissions in the Arctic could bring anthropogenic aerosol and BC in the Arctic summer, affecting the climate.

Predicting the liquefaction phenomena from shear velocity profiling: Empirical approach to 6.3 Mw, May 2006 Yogyakarta earthquake

Energy Technology Data Exchange (ETDEWEB)

Hartantyo, Eddy, E-mail: hartantyo@ugm.ac.id [PhD student, Physics Department, FMIPA, UGM. Sekip Utara Yogyakarta 55281 Indonesia (Indonesia); Brotopuspito, Kirbani S.; Sismanto; Waluyo [Geophysics Laboratory, FMIPA, Universitas Gadjah Mada, Sekip Utara Yogyakarta 55281 (Indonesia)

2015-04-24

The liquefactions phenomena have been reported after a shocking 6.5Mw earthquake hit Yogyakarta province in the morning at 27 May 2006. Several researchers have reported the damage, casualties, and soil failure due to the quake, including the mapping and analyzing the liquefaction phenomena. Most of them based on SPT test. The study try to draw the liquefaction susceptibility by means the shear velocity profiling using modified Multichannel Analysis of Surface Waves (MASW). This paper is a preliminary report by using only several measured MASW points. The study built 8-channel seismic data logger with 4.5 Hz geophones for this purpose. Several different offsets used to record the high and low frequencies of surface waves. The phase-velocity diagrams were stacked in the frequency domain rather than in time domain, for a clearer and easier dispersion curve picking. All codes are implementing in Matlab. From these procedures, shear velocity profiling was collected beneath each geophone’s spread. By mapping the minimum depth of shallow water table, calculating PGA with soil classification, using empirical formula for saturated soil weight from shear velocity profile, and calculating CRR and CSR at every depth, the liquefaction characteristic can be identify in every layer. From several acquired data, a liquefiable potential at some depth below water table was obtained.

Design of container velocity profile for the suppression of liquid sloshing

Science.gov (United States)

Kim, Dongjoo

2016-11-01

In many industrial applications, high-speed position control of a liquid container causes undesirable liquid vibrations called 'sloshing' which poses a control challenge in fast maneuvering and accurate positioning of containers. Recently, it has been shown that a control theory called 'input shaping' is successfully applied to reduce the sloshing, but its success comes at a cost of longer process time. Therefore, we aim to minimize liquid sloshing without increasing the process time when a container moves horizontally by a target distance within a limited time. In this study, sensing and feedback actuation are not permitted but the container velocity is allowed to be modified from a given triangular profile. A new design is proposed by applying input shaping to the container velocity with carefully selected acceleration time. That is, the acceleration time is chosen to be the 1st mode natural period, and the input shaper is determined based on the 3rd mode natural frequency. The proposed approach is validated by performing numerical simulations, which show that the simple modification of container velocity reduces the sloshing significantly without additional process time in a feedforward manner. Supported by the NRF programs (NRF-2015R1D1A1A01059675) of Korean government.

Application of one-dimensional model to calculate water velocity distributions over elastic elements simulating Canadian waterweed plants (Elodea Canadensis)

Science.gov (United States)

Kubrak, Elżbieta; Kubrak, Janusz; Rowiński, Paweł

2013-02-01

One-dimensional model for vertical profiles of longitudinal velocities in open-channel flows is verified against laboratory data obtained in an open channel with artificial plants. Those plants simulate Canadian waterweed which in nature usually forms dense stands that reach all the way to the water surface. The model works particularly well for densely spaced plants.

Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

Science.gov (United States)

Sheridan P. J.; Andrews, E.; Ogren, J A.; Tackett, J. L.; Winker, D. M.

2012-01-01

Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe.

Simultaneous Determination of Source Wavelet and Velocity Profile Using Impulsive Point-Source Reflections from a Layered Fluid

National Research Council Canada - National Science Library

Bube, K; Lailly, P; Sacks, P; Santosa, F; Symes, W. W

1987-01-01

.... We show that a quasi-impulsive, isotropic point source may be recovered simultaneously with the velocity profile from reflection data over a layered fluid, in linear (perturbation) approximation...

Impact of the vertical emission profiles on background gas-phase pollution simulated from the EMEP emissions over Europe

Directory of Open Access Journals (Sweden)

S. Mailler

2013-06-01

Full Text Available Five one-year air quality simulations over a domain covering Europe have been performed using the CHIMERE chemistry transport model and the EMEP emission dataset for Europe. These five simulations differ only by the representation of the effective emission heights for anthropogenic emissions: one has been run using the EMEP standard recommendations, three others with vertical injection profiles derived from the EMEP recommendations but multiplying the injection height by 0.75, 0.50 and 0.25, respectively, while the last one uses vertical profiles derived from the recent literature. It is shown that using injection heights lower than the EMEP recommendations leads to significantly improved simulation of background SO2, NO2 and O3 concentrations when compared to the Airbase station measurements.

Stratospheric NO2 vertical profile retrieved from ground-based Zenith-Sky DOAS observations at Kiruna, Sweden

Science.gov (United States)

Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Pukite, Janis; Van Roozendael, Michel; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

2014-05-01

Stratospheric NO2 destroys ozone and acts as a buffer against halogen-catalyzed ozone loss through the formation of reservoir species (ClONO2, BrONO2). Since the importance of both mechanisms depends on the altitude, the investigation of stratospheric NO2 vertical distribution can provide more insight into the role of nitrogen compounds in the destruction of ozone. Here we present stratospheric NO2 vertical profiles retrieved from twilight ground-based zenith-sky DOAS observations at Kiruna, Sweden (68.84°N, 20.41°E) covering 1997 - 2013 periods. This instrument observes zenith scattered sunlight. The sensitivity for stratospheric trace gases is highest during twilight due to the maximum altitude of the scattering profile and the light path through the stratosphere, which vary with the solar zenith angle. The profiling algorithm, based on the Optimal Estimation Method, has been developed by IASB-BIRA and successfully applied at other stations (Hendrick et al., 2004). The basic principle behind this profiling approach is that during twilight, the mean Rayleigh scattering altitude scans the stratosphere rapidly, providing height-resolved information on the absorption by stratospheric NO2. In this study, the long-term evolution of the stratospheric NO2 profile at polar latitude will be investigated. Hendrick, F., B. Barret, M. Van Roozendael, H. Boesch, A. Butz, M. De Mazière, F. Goutail, C. Hermans, J.-C. Lambert, K. Pfeilsticker, and J.-P. Pommereau, Retrieval of nitrogen dioxide stratospheric profiles from ground-based zenith-sky UV-visible observations: Validation of the technique through correlative comparisons, Atmospheric Chemistry and Physics, 4, 2091-2106, 2004

Two Years of Ozone Vertical Profiles Collected from Aircraft over California and the Pacific Ocean

Science.gov (United States)

Austerberry, D.; Yates, E. L.; Roby, M.; Chatfield, R. B.; Iraci, L. T.; Pierce, B.; Fairlie, T. D.; Johnson, B. J.; Ives, M.

2012-12-01

Tropospheric ozone transported across the Pacific Ocean has been strongly suggested to contribute substantially to surface ozone levels at several sites within Northern California's Sacramento Valley. Because this contribution can affect a city's ability to meet regulatory ozone limits, the influence of Pacific ozone transport has implications for air quality control strategies in the San Joaquin Valley (SJV). The Alpha Jet Atmospheric Experiment is designed to collect a multi-year data set of tropospheric ozone vertical profiles. Forty-four flights with ozone profiles were conducted between February 2nd, 2011 and August 9th, 2012, and approximately ten more flights are expected in the remainder of 2012. Twenty marine air profiles have been collected at sites including Trinidad Head and two locations tens of kilometers offshore at 37° N latitude. Good agreement is seen with ozonesondes launched from Trinidad Head. Additional profiles over Merced, California were obtained on many of these flight days. These in-situ measurements were conducted during spiral descents of H211's Alpha Jet at mid-day local times using a 2B Technologies Dual Beam Ozone Monitor. Hourly surface ambient ozone data were obtained from the California Air Resources Board's SJV monitoring sites. For each site, the Pearson linear correlation coefficient was calculated between ozone in a 300m vertical layer of an offshore profile and the surface site at varying time offsets from the time of the profile. Each site's local and regional ozone production component was estimated and removed. The resulting correlations suggest instances of Pacific ozone transport following some of the offshore observations. Real-Time Air Quality Modeling System (RAQMS) products constrained by assimilated satellite data model the transport of ozone enhancements and guide flight planning. RAQMS hindcasts also suggest that ozone transport to the surface of the SJV basin occurred following some of these offshore profiles

Development of an optimal velocity selection method with velocity obstacle

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Geuk; Oh, Jun Ho [KAIST, Daejeon (Korea, Republic of)

2015-08-15

The Velocity obstacle (VO) method is one of the most well-known methods for local path planning, allowing consideration of dynamic obstacles and unexpected obstacles. Typical VO methods separate a velocity map into a collision area and a collision-free area. A robot can avoid collisions by selecting its velocity from within the collision-free area. However, if there are numerous obstacles near a robot, the robot will have very few velocity candidates. In this paper, a method for choosing optimal velocity components using the concept of pass-time and vertical clearance is proposed for the efficient movement of a robot. The pass-time is the time required for a robot to pass by an obstacle. By generating a latticized available velocity map for a robot, each velocity component can be evaluated using a cost function that considers the pass-time and other aspects. From the output of the cost function, even a velocity component that will cause a collision in the future can be chosen as a final velocity if the pass-time is sufficiently long enough.

Spectra and gross features of vertical temperature and salinity profiles off the central west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Varkey, M.J.; Nagarajan, R.

Continuous vertical profiles of temperature and salinity recorded by a CTD-system from the continental slope and the continental rise off Goa, west coast of India, were used for delineating the gross statistical features of the fine structure...

Mesoscale kinematics derived from X-band Doppler radar observations of convective versus stratiform precipitation and comparison with GPS radiosonde profiles

Science.gov (United States)

Deshpande, Sachin M.; Dhangar, N.; Das, S. K.; Kalapureddy, M. C. R.; Chakravarty, K.; Sonbawne, S.; Konwar, M.

2015-11-01

Single Doppler analysis techniques known as velocity azimuth display (VAD) and volume velocity processing (VVP) are used to analyze kinematics of mesoscale flow such as horizontal wind and divergence using X-band Doppler weather radar observations, for selected cases of convective, stratiform, and shallow cloud systems near tropical Indian sites Pune (18.58°N, 73.92°E, above sea level (asl) 560 m) and Mandhardev (18.51°N, 73.85°E, asl 1297 m). The vertical profiles of horizontal wind estimated from radar VVP/VAD methods agree well with GPS radiosonde profiles, with the low-level jet at about 1.5 km during monsoon season well depicted in both. The vertical structure and temporal variability of divergence and reflectivity profiles are indicative of the dynamical and microphysical characteristics of shallow convective, deep convective, and stratiform cloud systems. In shallow convective systems, vertical development of reflectivity profiles is limited below 5 km. In deep convective systems, reflectivity values as large as 55 dBZ were observed above freezing level. The stratiform system shows the presence of a reflectivity bright band (~35 dBZ) near the melting level. The diagnosed vertical profiles of divergence in convective and stratiform systems are distinct. In shallow convective conditions, convergence was seen below 4 km with divergence above. Low-level convergence and upper level divergence are observed in deep convective profiles, while stratiform precipitation has midlevel convergence present between lower level and upper level divergence. The divergence profiles in stratiform precipitation exhibit intense shallow layers of "melting convergence" at 0°C level, near 4.5 km altitude, with a steep gradient on the both sides of the peak. The level of nondivergence in stratiform situations is lower than that in convective situations. These observed vertical structures of divergence are largely indicative of latent heating profiles in the atmosphere, an

Effects of wall roughness and entry length on void profile in vertical bubbly flow

International Nuclear Information System (INIS)

Takamasa, Tomoji

1988-01-01

An experimental study of upward air-water bubbly two-phase flow in an entry region was performed with various rough wall test tubes. The objective of the work is to clarify the effects of wall roughness and entry length on void profile. The fluid flows in the vertical circular test tube of 25 mm I.D. under nearly atmospheric pressure, at room temperature. The void profile changes from a pattern similar in appearance to the saddle shape which has local void peaks near the wall, into the power law shape whose curve is approximated by a power law formula, with increasing wall roughness and/or entry length. That is, wall roughness and entry length have a similar effect upon void profile. There are two patterns in the power law shape, a pattern with sharp center peak and a pattern with obtuse center peak. As wall roughness and/or entry length increase, the void profile changes from the former pattern to the latter pattern. At enough long entry length (L/D ≅ 150), every void profile has almost the same power law shape independent of wall roughness. Some void profiles are asymmetric to the axis. (author)

A study of the river velocity measurement techniques and analysis methods

Science.gov (United States)

Chung Yang, Han; Lun Chiang, Jie

2013-04-01

Velocity measurement technology can be traced back to the pitot tube velocity measurement method in the 18th century and today's velocity measurement technology use the acoustic and radar technology, with the Doppler principle developed technology advances, in order to develop the measurement method is more suitable for the measurement of velocity, the purpose is to get a more accurate measurement data and with the surface velocity theory, the maximum velocity theory and the indicator theory to obtain the mean velocity. As the main research direction of this article is to review the literature of the velocity measurement techniques and analysis methods, and to explore the applicability of the measurement method of the velocity measurement instruments, and then to describe the advantages and disadvantages of the different mean velocity profiles analysis method. Adequate review of the references of this study will be able to provide a reference for follow-up study of the velocity measurement. Review velocity measurement literature that different velocity measurement is required to follow the different flow conditions measured be upgraded its accuracy, because each flow rate measurement method has its advantages and disadvantages. Traditional velocity instrument can be used at low flow and RiverRAD microwave radar or imaging technology measurement method may be applied in high flow. In the tidal river can use the ADCP to quickly measure river vertical velocity distribution. In addition, urban rivers may be used the CW radar to set up on the bridge, and wide rivers can be used RiverRAD microwave radar to measure the velocities. Review the relevant literature also found that using Ultrasonic Doppler Current Profiler with the Chiu's theory to the velocity of observing automation work can save manpower and resources to improve measurement accuracy, reduce the risk of measurement, but the great variability of river characteristics in Taiwan and a lot of drifting floating

Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

Science.gov (United States)

Mamali, Dimitra; Marinou, Eleni; Sciare, Jean; Pikridas, Michael; Kokkalis, Panagiotis; Kottas, Michael; Binietoglou, Ioannis; Tsekeri, Alexandra; Keleshis, Christos; Engelmann, Ronny; Baars, Holger; Ansmann, Albert; Amiridis, Vassilis; Russchenberg, Herman; Biskos, George

2018-05-01

In situ measurements using unmanned aerial vehicles (UAVs) and remote sensing observations can independently provide dense vertically resolved measurements of atmospheric aerosols, information which is strongly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse mode (i.e. particles having radii > 0.5 µm), where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.

Mass flow and velocity profiles in Neurospora hyphae: partial plug flow dominates intra-hyphal transport.

Science.gov (United States)

Abadeh, Aryan; Lew, Roger R

2013-11-01

Movement of nuclei, mitochondria and vacuoles through hyphal trunks of Neurospora crassa were vector-mapped using fluorescent markers and green fluorescent protein tags. The vectorial movements of all three were strongly correlated, indicating the central role of mass (bulk) flow in cytoplasm movements in N. crassa. Profiles of velocity versus distance from the hyphal wall did not match the parabolic shape predicted by the ideal Hagen-Poiseuille model of flow at low Reynolds number. Instead, the profiles were flat, consistent with a model of partial plug flow due to the high concentration of organelles in the flowing cytosol. The intra-hyphal pressure gradients were manipulated by localized external osmotic treatments to demonstrate the dependence of velocity (and direction) on pressure gradients within the hyphae. The data support the concept that mass transport, driven by pressure gradients, dominates intra-hyphal transport. The transport occurs by partial plug flow due to the organelles in the cytosol.

Experimental study of the spatial distribution of the velocity field of sedimenting particles: mean velocity, pseudo-turbulent fluctuations, intrinsic convection

International Nuclear Information System (INIS)

Bernard-Michel, G.

2001-01-01

This work follows previous experiments from Nicolai et al. (95), Peysson and Guazzelli (98) and Segre et al. (97), which consisted in measures of the velocity of particles sedimenting in a liquid at low particular Reynolds numbers. Our goal, introduced in the first part with a bibliographic study, is to determinate the particles velocity fluctuations properties. The fluctuations are indeed of the same order as the mean velocity. We are proceeding with PIV Eulerian measures. The method is described in the second part. Its originality comes from measures obtained in a thin laser light sheet, from one side to the other of the cells, with a square section: the measures are therefore spatially localised. Four sets of cells and three sets of particles were used, giving access to ratios 'cell width over particle radius' ranging from about 50 up to 800. In the third part, we present the results concerning the velocity fluctuations structure and their spatial distribution. The intrinsic convection between to parallel vertical walls is also studied. The velocity fluctuations are organised in eddy structures. Their size (measured with correlation length) is independent of the volume fraction, contradicting the results of Segre et al. (97). The results concerning the velocity fluctuations spatial profiles - from one side to the other of the cell - confirm those published by Peysson and Guazzelli (98) in the case of stronger dilution. The evolution of the spatial mean velocity fluctuations confirms the results obtained by Segre et al. (97). The intrinsic convection is also observed in the case of strong dilutions. (author)

Investigation and visualization of liquid–liquid flow in a vertically mounted Hele-Shaw cell: flow regimes, velocity and shape of droplets

International Nuclear Information System (INIS)

Shad, S; Gates, I D; Maini, B B

2009-01-01

The motion and shape of a liquid drop flowing within a continuous, conveying liquid phase in a vertical Hele-Shaw cell were investigated experimentally. The continuous phase was more viscous and wetted the bounding walls of the Hele-Shaw cell. The gap between the Hele-Shaw plates was set equal to 0.0226 cm. Four different flow regimes were observed: (a) small-droplet flow, (b) elongated-droplet flow, (c) churn flow and (d) channel flow. At low capillary number, that is, when capillary forces are larger than viscous forces, the droplet shape was irregular and changed with time and distance, and it moved with lower velocity than that of the conveying phase. At higher capillary number, several different shapes of stabilized elongated and flattened drops were observed. In contrast to gas–liquid systems, the velocities of droplets are higher than that of conveying liquid. New correlations derived from dimensionless analysis and fitted to the experimental data were generated to predict the elongated-drop velocity and aspect ratio

Investigation and visualization of liquid-liquid flow in a vertically mounted Hele-Shaw cell: flow regimes, velocity and shape of droplets

Science.gov (United States)

Shad, S.; Gates, I. D.; Maini, B. B.

2009-11-01

The motion and shape of a liquid drop flowing within a continuous, conveying liquid phase in a vertical Hele-Shaw cell were investigated experimentally. The continuous phase was more viscous and wetted the bounding walls of the Hele-Shaw cell. The gap between the Hele-Shaw plates was set equal to 0.0226 cm. Four different flow regimes were observed: (a) small-droplet flow, (b) elongated-droplet flow, (c) churn flow and (d) channel flow. At low capillary number, that is, when capillary forces are larger than viscous forces, the droplet shape was irregular and changed with time and distance, and it moved with lower velocity than that of the conveying phase. At higher capillary number, several different shapes of stabilized elongated and flattened drops were observed. In contrast to gas-liquid systems, the velocities of droplets are higher than that of conveying liquid. New correlations derived from dimensionless analysis and fitted to the experimental data were generated to predict the elongated-drop velocity and aspect ratio.

The Spanwise Distribution of Losses in Prismatic Turbine Cascade with Non-Uniform Inlet Velocity Profile

Czech Academy of Sciences Publication Activity Database

Fürst, J.; Luxa, Martin; Šimurda, David

2014-01-01

Roč. 21, č. 2 (2014), s. 135-141 ISSN 1802-1484 R&D Projects: GA ČR(CZ) GAP101/10/1329 Institutional support: RVO:61388998 Keywords : prismatic turbine cascade * losses * velocity profile Subject RIV: BK - Fluid Dynamics http://www.engineeringmechanics.cz/obsahy.html?R=21&C=2

The shape of velocity dispersion profiles and the dynamical state of galaxy clusters

Science.gov (United States)

Costa, A. P.; Ribeiro, A. L. B.; de Carvalho, R. R.

2018-01-01

Motivated by the existence of the relationship between the dynamical state of clusters and the shape of the velocity dispersion profiles (VDPs), we study the VDPs for Gaussian (G) and non-Gaussian (NG) systems for a subsample of clusters from the Yang catalogue. The groups cover a redshift interval of 0.03 ≤ z ≤ 0.1 with halo mass ≥1014 M⊙. We use a robust statistical method, Hellinger Distance, to classify the dynamical state of the systems according to their velocity distribution. The stacked VDP of each class, G and NG, is then determined using either Bright or Faint galaxies. The stacked VDP for G groups displays a central peak followed by a monotonically decreasing trend which indicates a predominance of radial orbits, with the Bright stacked VDP showing lower velocity dispersions in all radii. The distinct features we find in NG systems are manifested not only by the characteristic shape of VDP, with a depression in the central region, but also by a possible higher infall rate associated with galaxies in the Faint stacked VDP.

HURRICANE AND SEVERE STORM SENTINEL (HS3) GLOBAL HAWK ADVANCED VERTICAL ATMOSPHERIC PROFILING SYSTEM (AVAPS) DROPSONDE SYSTEM V2

Data.gov (United States)

National Aeronautics and Space Administration — The Hurricane and Severe Storm Sentinel (HS3) Global Hawk Advanced Vertical Atmospheric Profiling System (AVAPS) Dropsonde System dataset was collected by the...

Application of wind-profiling radar data to the analysis of dust weather in the Taklimakan Desert.

Science.gov (United States)

Wang, Minzhong; Wei, Wenshou; Ruan, Zheng; He, Qing; Ge, Runsheng

2013-06-01

The Urumqi Institute of Desert Meteorology of the China Meteorological Administration carried out an atmospheric scientific experiment to detect dust weather using a wind-profiling radar in the hinterland of the Taklimakan Desert in April 2010. Based on the wind-profiling data obtained from this experiment, this paper seeks to (a) analyze the characteristics of the horizontal wind field and vertical velocity of a breaking dust weather in a desert hinterland; (b) calculate and give the radar echo intensity and vertical distribution of a dust storm, blowing sand, and floating dust weather; and (c) discuss the atmosphere dust counts/concentration derived from the wind-profiling radar data. Studies show that: (a) A wind-profiling radar is an upper-air atmospheric remote sensing system that effectively detects and monitors dust. It captures the beginning and ending of a dust weather process as well as monitors the sand and dust being transported in the air in terms of height, thickness, and vertical intensity. (b) The echo intensity of a blowing sand and dust storm weather episode in Taklimakan is about -1~10 dBZ while that of floating dust -1~-15 dBZ, indicating that the dust echo intensity is significantly weaker than that of precipitation but stronger than that of clear air. (c) The vertical shear of horizontal wind and the maintenance of low-level east wind are usually dynamic factors causing a dust weather process in Taklimakan. The moment that the low-level horizontal wind field finds a shear over time, it often coincides with the onset of a sand blowing and dust storm weather process. (d) When a blowing sand or dust storm weather event occurs, the atmospheric vertical velocity tends to be of upward motion. This vertical upward movement of the atmosphere supported with a fast horizontal wind and a dry underlying surface carries dust particles from the ground up to the air to form blown sand or a dust storm.

Vertical profiles of black carbon measured by a micro-aethalometer in summer in the North China Plain

Science.gov (United States)

Ran, Liang; Deng, Zhaoze; Xu, Xiaobin; Yan, Peng; Lin, Weili; Wang, Ying; Tian, Ping; Wang, Pucai; Pan, Weilin; Lu, Daren

2016-08-01

Black carbon (BC) is a dominant absorber in the visible spectrum and a potent factor in climatic effects. Vertical profiles of BC were measured using a micro-aethalometer attached to a tethered balloon during the Vertical Observations of trace Gases and Aerosols (VOGA) field campaign, in summer 2014 at a semirural site in the North China Plain (NCP). The diurnal cycle of BC vertical distributions following the evolution of the mixing layer (ML) was investigated for the first time in the NCP region. Statistical parameters including identified mixing height (Hm) and average BC mass concentrations within the ML (Cm) and in the free troposphere (Cf) were obtained for a selected dataset of 67 vertical profiles. Hm was usually lower than 0.2 km in the early morning and rapidly rose thereafter due to strengthened turbulence. The maximum height of the ML was reached in the late afternoon. The top of a full developed ML exceeded 1 km on sunny days in summer, while it stayed much lower on cloudy days. The sunset triggered the collapse of the ML, and a stable nocturnal boundary layer (NBL) gradually formed. Accordingly, the highest level Cm was found in the early morning and the lowest was found in the afternoon. In the daytime, BC was almost uniformly distributed within the ML and significantly decreased above the ML. During the field campaign, Cm averaged about 5.16 ± 2.49 µg m-3, with a range of 1.12 to 14.49 µg m-3, comparable with observational results in many polluted urban areas such as Milan in Italy and Shanghai in China. As evening approached, BC gradually built up near the surface and exponentially declined with height. In contrast to the large variability found both in Hm and Cm, Cf stayed relatively unaffected through the day. Cf was less than 10 % of the ground level under clean conditions, while it amounted to half of the ground level in some polluted cases. In situ measurements of BC vertical profiles would hopefully have an important implication for

A Laboratory Study of Vortical Structures in Rotating Convection Plumes

Science.gov (United States)

Fu, Hao; Sun, Shiwei; Wang, Yuan; Zhou, Bowen; Thermal Turbulence Research Team

2015-11-01

A laboratory study of the columnar vortex structure in rotating Rayleigh-Bénard convection is conducted. A rectangular water tank is uniformly heated from below and cooled from above, with Ra = (6 . 35 +/- 0 . 77) ×107 , Ta = 9 . 84 ×107 , Pr = 7 . 34 . The columnar vortices are vertically aligned and quasi steady. Two 2D PIV systems were used to measure velocity field. One system performs horizontal scans at 9 different heights every 13.6s, covering 62% of the total depth. The other system scans vertically to obtain the vertical velocity profile. The measured vertical vorticity profiles of most vortices are quasi-linear with height while the vertical velocities are nearly uniform with only a small curvature. A simple model to deduce vertical velocity profile from vertical vorticity profile is proposed. Under quasi-steady and axisymmetric conditions, a ``vortex core'' assumption is introduced to simplify vertical vorticity equation. A linear ODE about vertical velocity is obtained whenever a vertical vorticity profile is given and solved with experimental data as input. The result is approximately in agreement with the measurement. This work was supported by Undergraduates Training Project (J1103410).

Visualizing flow fields using acoustic Doppler current profilers and the Velocity Mapping Toolbox

Science.gov (United States)

Jackson, P. Ryan

2013-01-01

The purpose of this fact sheet is to provide examples of how the U.S. Geological Survey is using acoustic Doppler current profilers for much more than routine discharge measurements. These instruments are capable of mapping complex three-dimensional flow fields within rivers, lakes, and estuaries. Using the Velocity Mapping Toolbox to process the ADCP data allows detailed visualization of the data, providing valuable information for a range of studies and applications.

Vertical velocity variances and Reynold stresses at Brookhaven

DEFF Research Database (Denmark)

Busch, Niels E.; Brown, R.M.; Frizzola, J.A.

1970-01-01

Results of wind tunnel tests of the Brookhaven annular bivane are presented. The energy transfer functions describing the instrument response and the numerical filter employed in the data reduction process have been used to obtain corrected values of the normalized variance of the vertical wind v...

Coma Berenices: The First Evidence for Incomplete Vertical Phase-mixing in Local Velocity Space with RAVE—Confirmed with Gaia DR2

Science.gov (United States)

Monari, G.; Famaey, B.; Minchev, I.; Antoja, T.; Bienaymé, O.; Gibson, B. K.; Grebel, E. K.; Kordopatis, G.; McMillan, P.; Navarro, J.; Parker, Q. A.; Quillen, A. C.; Reid, W.; Seabroke, G.; Siebert, A.; Steinmetz, M.; Wyse, R. F. G.; Zwitter, T.

2018-05-01

Before the publication of the Gaia DR2 we confirmed with RAVE and TGAS an observation recently made with the GALAH survey by Quillen ey al. concerning the Coma Berenices moving group in the Solar neighbourhood, namely that it is only present at negative Galactic latitudes. This allowed us to show that it is coherent in vertical velocity, providing a first evidence for incomplete vertical phase-mixing. We estimated for the first time from dynamical arguments that the moving group must have formed at most ~ 1.5 Gyr ago, and related this to a pericentric passage of the Sagittarius dwarf satellite galaxy. The present note is a rewritten version of the original arXiv post on this result now also including a confirmation of our finding with Gaia DR2.

Retrieval of convective boundary layer wind field statistics from radar profiler measurements in conjunction with large eddy simulation

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Danny Scipión

2009-05-01

Full Text Available The daytime convective boundary layer (CBL is characterized by strong turbulence that is primarily forced by buoyancy transport from the heated underlying surface. The present study focuses on an example of flow structure of the CBL as observed in the U.S. Great Plains on June 8, 2007. The considered CBL flow has been reproduced using a numerical large eddy simulation (LES, sampled with an LES-based virtual boundary layer radar (BLR, and probed with an actual operational radar profiler. The LES-generated CBL flow data are then ingested by the virtual BLR and treated as a proxy for prevailing atmospheric conditions. The mean flow and turbulence parameters retrieved via each technique (actual radar profiler, virtual BLR, and LES have been cross-analyzed and reasonable agreement was found between the CBL wind parameters obtained from the LES and those measured by the actual radar. Averaged vertical velocity variance estimates from the virtual and actual BLRs were compared with estimates calculated from the LES for different periods of time. There is good agreement in the estimates from all three sources. Also, values of the vertical velocity skewness retrieved by all three techniques have been inter-compared as a function of height for different stages of the CBL evolution, showing fair agreement with each other. All three retrievals contain positively skewed vertical velocity structure throughout the main portion of the CBL. Radar estimates of the turbulence kinetic energy (eddy dissipation rate (ε have been obtained based on the Doppler spectral width of the returned signal for the vertical radar beam. The radar estimates were averaged over time in the same fashion as the LES output data. The agreement between estimates was generally good, especially within the mixing layer. Discrepancies observed above the inversion layer may be explained by a weak turbulence signal in particular flow configurations. The virtual BLR produces voltage

Study of flow past an exponentially accelerated isothermal vertical plate in the presence of chemical reaction

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Muthucumaraswamy R.

2010-01-01

Full Text Available Theoretical study of unsteady flow past an exponentially accelerated infinite isothermal vertical plate with variable mass diffusion has been presented in the presence of homogeneous chemical reaction of first order. The plate temperature is raised to Tw and species concentration level near the plate is made to rise linearly with time. The dimensionless governing equations are solved using Laplace-transform technique. The velocity profiles are studied for different physical parameters like chemical reaction parameter, thermal Grashof number, mass Grashof number, a and time. It is observed that the velocity increases with increasing values of a or t. But the trend is just reversed with respect to K.

Effects of rotation on MHD flow past an accelerated isothermal vertical plate with heat and mass diffusion

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Muthucumaraswamy R.

2010-01-01

Full Text Available An exact analysis of rotation effects on unsteady flow of an incompressible and electrically conducting fluid past a uniformly accelerated infinite isothermal vertical plate, under the action of transversely applied magnetic field has been presented. The plate temperature is raised to Tw and the concentration level near the plate is also raised to C′w . The dimensionless governing equations are solved using Laplace-transform technique. The velocity profiles, temperature and concentration are studied for different physical parameters like thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that the velocity increases with increasing values of thermal Grashof number or mass Grashof number. It is also observed that the velocity increases with decreasing magnetic field parameter.

Spatial distribution and vertical variation of arsenic in Guangdong soil profiles, China

International Nuclear Information System (INIS)

Zhang, H.H.; Yuan, H.X.; Hu, Y.G.; Wu, Z.F.; Zhu, L.A.; Zhu, L.; Li, F.B.; LI, D.Q.

2006-01-01

Total of 260 soil profiles were reported to investigate the arsenic spatial distribution and vertical variation in Guangdong province. The arsenic concentration followed an approximately lognormal distribution. The arsenic geometric mean concentration of 10.4 mg/kg is higher than that of China. An upper baseline concentration of 23.4 mg/kg was estimated for surface soils. The influence of soil properties on arsenic concentration was not important. Arsenic spatial distributions presented similar patterns that high arsenic concentration mainly located in limestone, and sandshale areas, indicating that soil arsenic distribution was dependent on bedrock properties than anthropogenic inputs. Moreover, from A- to C-horizon arsenic geometric mean concentrations had an increasing tendency of 10.4, 10.7 to 11.3 mg/kg. This vertical variation may be related to the lower soil organic matter and soil degradation and erosion. Consequently, the soil arsenic export into surface and groundwaters would reach 1040 t year -1 in the study area. - Soil arsenic movement export is a potential threat to the water quality of the study area

Eulerian-Lagrangian analysis for particle velocities and trajectories in a pure wave motion using particle image velocimetry.

Science.gov (United States)

Umeyama, Motohiko

2012-04-13

This paper investigates the velocity and the trajectory of water particles under surface waves, which propagate at a constant water depth, using particle image velocimetry (PIV). The vector fields and vertical distributions of velocities are presented at several phases in one wave cycle. The third-order Stokes wave theory was employed to express the physical quantities. The PIV technique's ability to measure both temporal and spatial variations of the velocity was proved after a series of attempts. This technique was applied to the prediction of particle trajectory in an Eulerian scheme. Furthermore, the measured particle path was compared with the positions found theoretically by integrating the Eulerian velocity to the higher order of a Taylor series expansion. The profile of average travelling distance is also presented with a solution of zero net mass flux in a closed wave flume.

Seismic Velocity Structure across the Hayward Fault Zone Near San Leandro, California

Science.gov (United States)

Strayer, L. M.; Catchings, R.; Chan, J. H.; Richardson, I. S.; McEvilly, A.; Goldman, M.; Criley, C.; Sickler, R. R.

2017-12-01

In Fall 2016 we conducted the East Bay Seismic Investigation, a NEHRP-funded collaboration between California State University, East Bay and the United State Geological Survey. The study produced a large volume of seismic data, allowing us to examine the subsurface across the East Bay plain and hills using a variety of geophysical methods. We know of no other survey performed in the past that has imaged this area, at this scale, and with this degree of resolution. Initial models show that seismic velocities of the Hayward Fault Zone (HFZ), the East Bay plain, and the East Bay hills are illuminated to depths of 5-6 km. We used explosive sources at 1-km intervals along a 15-km-long, NE-striking ( 055°), seismic line centered on the HFZ. Vertical- and horizontal-component sensors were spaced at 100 m intervals along the entire profile, with vertical-component sensors at 20 m intervals across mapped or suspected faults. Preliminary seismic refraction tomography across the HFZ, sensu lato, (includes sub-parallel, connected, and related faults), shows that the San Leandro Block (SLB) is a low-velocity feature in the upper 1-3 km, with nearly the same Vp as the adjacent Great Valley sediments to the east, and low Vs values. In our initial analysis we can trace the SLB and its bounding faults (Hayward, Chabot) nearly vertically, to at least 2-4 km depth. Similarly, preliminary migrated reflection images suggest that many if not all of the peripheral reverse, strike-slip and oblique-slip faults of the wider HFZ dip toward the SLB, into a curtain of relocated epicenters that define the HFZ at depth, indicative of a `flower-structure'. Preliminary Vs tomography identifies another apparently weak zone at depth, located about 1.5 km east of the San Leandro shoreline, that may represent the northward continuation of the Silver Creek Fault. Centered 4 km from the Bay, there is a distinctive, 2 km-wide, uplifted, horst-like, high-velocity structure (both Vp & Vs) that bounds the

The spectral link in mean-velocity profile of turbulent plane-Couette flows

Science.gov (United States)

Zhang, Dongrong; Gioia, Gustavo; Chakraborty, Pinaki

2015-03-01

In turbulent pipe and plane-Couette flows, the mean-velocity profile (MVP) represents the distribution of local mean (i.e., time-averaged) velocity on the cross section of a flow. The spectral theory of MVP in pipe flows (Gioia et al., PRL, 2010) furnishes a long-surmised link between the MVP and turbulent energy spectrum. This missing spectral link enables new physical insights into an imperfectly understood phenomenon (the MVP) by building on the well-known structure of the energy spectrum. Here we extend this theory to plane-Couette flows. Similar to pipe flows, our analysis allows us to express the MVP as a functional of the spectrum, and to relate each feature of the MVP relates to a specific spectral range: the buffer layer to the dissipative range, the log layer to the inertial range, and the wake (or the lack thereof) to the energetic range. We contrast pipe and plane-Couette flows in light of the theory.

Free Convection Heat and Mass Transfer MHD Flow in a Vertical Channel in the Presence of Chemical Reaction

Directory of Open Access Journals (Sweden)

R. N. Barik

2013-09-01

Full Text Available An analysis is made to study the effects of diffusion-thermo and chemical reaction on fully developed laminar MHD flow of electrically conducting viscous incompressible fluid in a vertical channel formed by two vertical parallel plates was taken into consideration with uniform temperature and concentration. The analytical solution by Laplace transform technique of partial differential equations is used to obtain the expressions for the velocity, temperature and concentration. It is interesting to note that during the course of computation, the transient solution at large time coincides with steady state solution derived separately and the diffusion-thermo effect creates an anomalous situation in temperature and velocity profiles for small Prandtl numbers. The study is restricted to only destructive reaction and non-conducting case cannot be derived as a particular case still it is quite interesting and more realistic than the earlier one.

A COMPARITIVE STUDY USING GEOMETRIC AND VERTICAL PROFILE FEATURES DERIVED FROM AIRBORNE LIDAR FOR CLASSIFYING TREE GENERA

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C. Ko

2012-07-01

Full Text Available We present a comparative study between two different approaches for tree genera classification using descriptors derived from tree geometry and those derived from the vertical profile analysis of LiDAR point data. The different methods provide two perspectives for processing LiDAR point clouds for tree genera identification. The geometric perspective analyzes individual tree crowns in relation to valuable information related to characteristics of clusters and line segments derived within crowns and overall tree shapes to highlight the spatial distribution of LiDAR points within the crown. Conversely, analyzing vertical profiles retrieves information about the point distributions with respect to height percentiles; this perspective emphasizes of the importance that point distributions at specific heights express, accommodating for the decreased point density with respect to depth of canopy penetration by LiDAR pulses. The targeted species include white birch, maple, oak, poplar, white pine and jack pine at a study site northeast of Sault Ste. Marie, Ontario, Canada.

Vertical profiles of ozone, carbon monoxide, and dew-point temperature obtained during GTE/CITE 1, October-November 1983. [Chemical Instrumentation Test and Evaluation

Science.gov (United States)

Fishman, Jack; Gregory, Gerald L.; Sachse, Glen W.; Beck, Sherwin M.; Hill, Gerald F.

1987-01-01

A set of 14 pairs of vertical profiles of ozone and carbon monoxide, obtained with fast-response instrumentation, is presented. Most of these profiles, which were measured in the remote troposphere, also have supporting fast-response dew-point temperature profiles. The data suggest that the continental boundary layer is a source of tropospheric ozone, even in October and November, when photochemical activity should be rather small. In general, the small-scale vertical variability between CO and O3 is in phase. At low latitudes this relationship defines levels in the atmosphere where midlatitude air is being transported to lower latitudes, since lower dew-point temperatures accompany these higher CO and O3 concentrations. A set of profiles which is suggestive of interhemispheric transport is also presented. Independent meteorological analyses support these interpretations.

LOCAL VELOCITY PROFILES MEASURED BY PIV IN AN VESSEL AGITATED BY RUSHTON TURBINE

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Radek Šulc

2014-12-01

Full Text Available The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV. The experiments were carried out in a fully baffled cylindrical flat bottom vessel 300 mm in inner diameter. The tank was agitated by a Rushton turbine 100 mm in diameter. The velocity fields were measured for three impeller rotation speeds 300 rpm, 450 rpm and 600 rpm and the corresponding Reynolds numbers in the range 50 000 < Re < 100 000, which means that the fully-developed turbulent flow was reached. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller rotational speed. The velocity profiles were averaged, and were expressed by Chebyshev polynomials of the 1st order. Although the experimentally investigated area was relatively far from the impeller, and it was located in upward flow to the impeller, no state of local isotropy was found. The ratio of the axial rms fluctuation velocity to the radial component was found to be in the range from 0.523 to 0.768. The axial turbulence intensity was found to be in the range from 0.293 to 0.667, which corresponds to a high turbulence intensity.

Stochastic Analysis of Natural Convection in Vertical Channels with Random Wall Temperature

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Ryoichi Chiba

2017-01-01

Full Text Available This study attempts to derive the statistics of temperature and velocity fields of laminar natural convection in a heated vertical channel with random wall temperature. The wall temperature is expressed as a random function with respect to time, or a random process. First, analytical solutions of the transient temperature and flow velocity fields for an arbitrary temporal variation in the channel wall temperature are obtained by the integral transform and convolution theorem. Second, the autocorrelations of the temperature and velocity are formed from the solutions, assuming a stationarity in time. The mean square values of temperature and velocity are computed under the condition that the fluctuation in the channel wall temperature can be considered as white noise or a stationary Markov process. Numerical results demonstrate that a decrease in the Prandtl number or an increase in the correlation time of the random process increases the level of mean square velocity but does not change its spatial distribution tendency, which is a bell-shaped profile with a peak at a certain horizontal distance from the channel wall. The peak position is not substantially affected by the Prandtl number or the correlation time.

Vertical profiles of lung deposited surface area concentration of particulate matter measured with a drone in a street canyon.

Science.gov (United States)

Kuuluvainen, Heino; Poikkimäki, Mikko; Järvinen, Anssi; Kuula, Joel; Irjala, Matti; Dal Maso, Miikka; Keskinen, Jorma; Timonen, Hilkka; Niemi, Jarkko V; Rönkkö, Topi

2018-05-23

The vertical profiles of lung deposited surface area (LDSA) concentration were measured in an urban street canyon in Helsinki, Finland, by using an unmanned aerial system (UAS) as a moving measurement platform. The street canyon can be classified as an avenue canyon with an aspect ratio of 0.45 and the UAS was a multirotor drone especially modified for emission measurements. In the experiments of this study, the drone was equipped with a small diffusion charge sensor capable of measuring the alveolar LDSA concentration of particles. The drone measurements were conducted during two days on the same spatial location at the kerbside of the street canyon by flying vertically from the ground level up to an altitude of 50 m clearly above the rooftop level (19 m) of the nearest buildings. The drone data were supported by simultaneous measurements and by a two-week period of measurements at nearby locations with various instruments. The results showed that the averaged LDSA concentrations decreased approximately from 60 μm 2 /cm 3 measured close to the ground level to 36-40 μm 2 /cm 3 measured close to the rooftop level of the street canyon, and further to 16-26 μm 2 /cm 3 measured at 50 m. The high-resolution measurement data enabled an accurate analysis of the functional form of vertical profiles both in the street canyon and above the rooftop level. In both of these regions, exponential fits were used and the parameters obtained from the fits were thoroughly compared to the values found in literature. The results of this study indicated that the role of turbulent mixing caused by traffic was emphasized compared to the street canyon vortex as a driving force of the dispersion. In addition, the vertical profiles above the rooftop level showed a similar exponential decay compared to the profiles measured inside the street canyon. Copyright © 2018 Elsevier Ltd. All rights reserved.

3-D x-ray mirror metrology with a vertical scanning long trace profiler

International Nuclear Information System (INIS)

Takacs, P.Z.; Li, H.; Li, X.; Grindel, M.W.

1996-01-01

The long trace profiler (LTP) was originally developed at Brookhaven National Laboratory for the specific purpose of measuring the surface figure of large cylindrical mirrors used at grazing incidence in synchrotron radiation (SR) beamlines. In its original configuration, it could measure only along one line down the center of the cylinder. A single linear profile is often sufficient to gauge the quality of the optical surface on these kinds of mirrors. For some applications it is necessary to measure the topography of the entire surface, not just along one line but over a grid that covers the entire surface area. We have modified a standard LTP to enable measurement of the complete surface of Wolter telescope optics in a vertical configuration. The vertical scanning LTP (VSLTP) is capable of producing a complete 3-D map of the surface topography errors relative to the ideal desired surface on complete segments of paraboloids and hyperboloids. The instrument uses a penta prism assembly to scan the probe beam in the longitudinal direction parallel to the mirror symmetry axis and uses a precision rotary stage to provide scans in the azimuthal direction. A Risley prism pair and a dove prism are used to orient the probe beam in the proper direction for the azimuthal scans. The repeatability of the prototype instrument is better than 20 nm over trace lengths of 35 mm with a slope measurement accuracy of about 1 microradian. copyright 1996 American Institute of Physics

CFD modelling and validation of upward bubbly flow in an adiabatic vertical pipe using the quadrature method of moments

International Nuclear Information System (INIS)

Peña-Monferrer, C.; Passalacqua, A.; Chiva, S.; Muñoz-Cobo, J.L.

2016-01-01

Highlights: • A population balance equation solved with QMOM approximation is implemented in OpenFOAM. • Available models for interfacial forces and bubble induced turbulence are analyzed. • A vertical pipe flow is simulated for different bubbly flow conditions. • Two-phase flow characteristics in vertical pipes are properly predicted. - Abstract: An Eulerian–Eulerian approach was investigated to model adiabatic bubbly flow with CFD techniques. In the framework of the OpenFOAM"® software, a two-fluid model solver was modified to include a population balance equation, solved with the quadrature method of moments approximation to predict upward bubbly flow in vertical pipes considering the polydisperse nature of two-phase flow. Some progress have been made recently solving population balance equations in OpenFOAM"® and this research aims to extend its application to the case of vertical pipes under different conditions of liquid and gas velocities. In order to test the solver for nuclear applications, interfacial forces and bubble induced turbulence models were included to provide to this solver the capability to correctly predict the behavior of the continuous and disperse phases. Two-phase flow experiments with different superficial velocities of gas and liquid are used to validate the model and its implementation. Radial profiles of void fraction, gas and liquid velocities, Sauter mean diameter and turbulence intensity are compared to the computational results. These results are in satisfactory agreement with the experiments, showing the capability of the solver to predict two-phase flow characteristics.

Developing Buoyancy Driven Flow of a Nanofluid in a Vertical Channel Subject to Heat Flux

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Nirmal C. Sacheti

2014-01-01

Full Text Available The developing natural convective flow of a nanofluid in an infinite vertical channel with impermeable bounding walls has been investigated. It is assumed that the nanofluid is dominated by two specific slip mechanisms and that the channel walls are subject to constant heat flux and isothermal temperature, respectively. The governing nonlinear partial differential equations coupling different transport processes have been solved numerically. The variations of velocity, temperature, and nanoparticles concentration have been discussed in relation to a number of physical parameters. It is seen that the approach to the steady-state profiles of velocity and temperature in the present work is different from the ones reported in a previous study corresponding to isothermal wall conditions.

Reexamination of the Classical View of how Drag-Reducing Polymer Solutions Modify the Mean Velocity Profile: Baseline Results

Science.gov (United States)

Farsiani, Yasaman; Baade, Jacquelyne; Elbing, Brian

2016-11-01

Recent numerical and experimental data have shown that the classical view of how drag-reducing polymer solutions modify the mean turbulent velocity profile is incorrect. The classical view is that the log-region is unmodified from the traditional law-of-the-wall for Newtonian fluids, though shifted outward. Thus the current study reexamines the modified velocity distribution and its dependence on flow and polymer properties. Based on previous work it is expected that the behavior will depend on the Reynolds number, Weissenberg number, ratio of solvent viscosity to the zero-shear viscosity, and the ratio between the coiled and fully extended polymer chain lengths. The long-term objective for this study includes a parametric study to assess the velocity profile sensitivity to each of these parameters. This study will be performed using a custom design water tunnel, which has a test section that is 1 m long with a 15.2 cm square cross section and a nominal speed range of 1 to 10 m/s. The current presentation focuses on baseline (non-polymeric) measurements of the velocity distribution using PIV, which will be used for comparison of the polymer modified results. Preliminary polymeric results will also be presented. This work was supported by NSF Grant 1604978.

Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

KAUST Repository

Yu, Han

2016-04-26

We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green\\'s function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

Eccentricity samples: Implications on the potential and the velocity distribution

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Cubarsi R.

2017-01-01

Full Text Available Planar and vertical epicycle frequencies and local angular velocity are related to the derivatives up to the second order of the local potential and can be used to test the shape of the potential from stellar disc samples. These samples show a more complex velocity distribution than halo stars and should provide a more realistic test. We assume an axisymmetric potential allowing a mixture of independent ellipsoidal velocity distributions, of separable or Staeckel form in cylindrical or spherical coordinates. We prove that values of local constants are not consistent with a potential separable in addition in cylindrical coordinates and with a spherically symmetric potential. The simplest potential that fits the local constants is used to show that the harmonical and non-harmonical terms of the potential are equally important. The same analysis is used to estimate the local constants. Two families of nested subsamples selected for decreasing planar and vertical eccentricities are used to borne out the relation between the mean squared planar and vertical eccentricities and the velocity dispersions of the subsamples. According to the first-order epicycle model, the radial and vertical velocity components provide accurate information on the planar and vertical epicycle frequencies. However, it is impossible to account for the asymmetric drift which introduces a systematic bias in estimation of the third constant. Under a more general model, when the asymmetric drift is taken into account, the rotation velocity dispersions together with their asymmetric drift provide the correct fit for the local angular velocity. The consistency of the results shows that this new method based on the distribution of eccentricities is worth using for kinematic stellar samples. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. No 176011: Dynamics and Kinematics of Celestial Bodies and Systems

Vertical profiles of aerosol optical properties over central Illinois and comparison with surface and satellite measurements

Directory of Open Access Journals (Sweden)

P. J. Sheridan

2012-12-01

Full Text Available Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1 measure the in situ aerosol properties and determine their vertical and temporal variability and (2 relate these aircraft measurements to concurrent surface and satellite measurements. The primary profile location was within 15 km of the NOAA/ESRL surface aerosol monitoring station near Bondville, Illinois. Identical instruments at the surface and on the aircraft ensured that the data from both platforms would be directly comparable and permitted a determination of how representative surface aerosol properties were of the lower column. Aircraft profiles were also conducted occasionally at two other nearby locations to increase the frequency of A-Train satellite underflights for the purpose of comparing in situ and satellite-retrieved aerosol data. Measurements of aerosol properties conducted at low relative humidity over the Bondville site compare well with the analogous surface aerosol data and do not indicate any major sampling issues or that the aerosol is radically different at the surface compared with the lowest flyby altitude of ~ 240 m above ground level. Statistical analyses of the in situ vertical profile data indicate that aerosol light scattering and absorption (related to aerosol amount decreases substantially with increasing altitude. Parameters related to the nature of the aerosol (e.g., single-scattering albedo, Ångström exponent, etc., however, are relatively constant throughout the mixed layer, and do not vary as much as the aerosol amount throughout the profile. While individual profiles often showed more variability, the median in situ single-scattering albedo was 0.93–0.95 for all sampled altitudes. Several parameters (e.g., submicrometer scattering fraction, hemispheric backscattering fraction, and

High-resolution humidity profiles retrieved from wind profiler radar measurements

Science.gov (United States)

Saïd, Frédérique; Campistron, Bernard; Di Girolamo, Paolo

2018-03-01

The retrieval of humidity profiles from wind profiler radars has already been documented in the past 30 years and is known to be neither as straightforward and nor as robust as the retrieval of the wind velocity. The main constraint to retrieve the humidity profile is the necessity to combine measurements from the wind profiler and additional measurements (such as observations from radiosoundings at a coarser time resolution). Furthermore, the method relies on some assumptions and simplifications that restrict the scope of its application. The first objective of this paper is to identify the obstacles and limitations and solve them, or at least define the field of applicability. To improve the method, we propose using the radar capacity to detect transition levels, such as the top level of the boundary layer, marked by a maximum in the radar reflectivity. This forces the humidity profile from the free troposphere and from the boundary layer to coincide at this level, after an optimization of the calibration coefficients, and reduces the error. The resulting mean bias affecting the specific humidity profile never exceeds 0.25 g kg-1. The second objective is to explore the capability of the algorithm to retrieve the humidity vertical profiles for an operational purpose by comparing the results with observations from a Raman lidar.

Moisture profile measurements of concrete samples in vertical flow by gamma ray attenuation method. Medidas do perfil de umidade de amostras de concreto em infiltracao vertical, atraves da atenuacao de raios gama

Energy Technology Data Exchange (ETDEWEB)

Appoloni, C R; Nardocci, A C; Obuti, M M [Universidade Estadual de Londrina, PR (Brazil). Dept. de Fisica

1988-04-01

This work deals with the study of the water diffusion in concrete by the gamma ray attenuation method. The moisture profiles, [theta] (z,t), of the vertical water flow were determined in concrete samples of different trace and porosity. The data were taken with a vertical and horizontal measurement table, a [sup 60] Co gamma ray source, a NaI (T) scintillation detector and the standard gamma ray spectrometry electronic. The [theta] (z,t) data analysis is presented using a phenomenological model of the moisture profile temporal evolution in heterogeneous materials. Two other models, Cell and Sandwich, were also applied to determine the attenuation coefficient of a non-homogeneous media from the attenuation coefficients of the components, taking into account particles-size effects. (author).

Analysis of photosynthate translocation velocity and measurement of weighted average velocity in transporting pathway of crops

International Nuclear Information System (INIS)

Ge Cailin; Luo Shishi; Gong Jian; Zhang Hao; Ma Fei

1996-08-01

The translocation profile pattern of 14 C-photosynthate along the transporting pathway in crops were monitored by pulse-labelling a mature leaf with 14 CO 2 . The progressive spreading of translocation profile pattern along the sheath or stem indicates that the translocation of photosynthate along the sheath or stem proceed with a range of velocities rather than with just a single velocity. The method for measuring the weighted average velocity of photosynthate translocation along the sheath or stem was established in living crops. The weighted average velocity and the maximum velocity of photosynthate translocation along the sheath in rice and maize were measured actually. (4 figs., 3 tabs.)

Approximation of wave action flux velocity in strongly sheared mean flows

Science.gov (United States)

Banihashemi, Saeideh; Kirby, James T.; Dong, Zhifei

2017-08-01

Spectral wave models based on the wave action equation typically use a theoretical framework based on depth uniform current to account for current effects on waves. In the real world, however, currents often have variations over depth. Several recent studies have made use of a depth-weighted current U˜ due to [Skop, R. A., 1987. Approximate dispersion relation for wave-current interactions. J. Waterway, Port, Coastal, and Ocean Eng. 113, 187-195.] or [Kirby, J. T., Chen, T., 1989. Surface waves on vertically sheared flows: approximate dispersion relations. J. Geophys. Res. 94, 1013-1027.] in order to account for the effect of vertical current shear. Use of the depth-weighted velocity, which is a function of wavenumber (or frequency and direction) has been further simplified in recent applications by only utilizing a weighted current based on the spectral peak wavenumber. These applications do not typically take into account the dependence of U˜ on wave number k, as well as erroneously identifying U˜ as the proper choice for current velocity in the wave action equation. Here, we derive a corrected expression for the current component of the group velocity. We demonstrate its consistency using analytic results for a current with constant vorticity, and numerical results for a measured, strongly-sheared current profile obtained in the Columbia River. The effect of choosing a single value for current velocity based on the peak wave frequency is examined, and we suggest an alternate strategy, involving a Taylor series expansion about the peak frequency, which should significantly extend the range of accuracy of current estimates available to the wave model with minimal additional programming and data transfer.

Influence of Saharan dust outbreaks and atmospheric stability upon vertical profiles of size-segregated aerosols and water vapor

Science.gov (United States)

Giménez, Joaquín; Pastor, Carlos; Castañer, Ramón; Nicolás, José; Crespo, Javier; Carratalá, Adoración

2010-01-01

Vertical profiles of aerosols and meteorological parameters were obtained using a hot air balloon and motorized paraglider. They were studied under anticyclonic conditions in four different contexts. Three flights occurred near sunrise, and one took place in the central hours of the day. The effects of North African dust intrusions were analyzed, whose entrance to the study area took place above the Stable Boundary Layer (SBL) in flight 1 and below it in flight 2. These flights have been compared with a non-intrusion situation (flight 3). A fourth flight characterized the profiles in the central hours of the day with a well-formed Convective Boundary Layer (CBL). With respect to the particle number distribution, the results show that not all sizes increase within the presence of an intrusion; during the first flight the smallest particles were not affected. The particle sizes affected in the second flight fell within the 0.35-2.5 μm interval. Under situations of convective dynamics, the reduction percentage of the particle number concentration reduces with increasing altitude, independently of their size, with respect to stability conditions. The negative vertical gradient for aerosols and water vapor, characteristic of a highly stable SBL (flight 3) becomes a constant profile within a CBL (flight 4). There are two situations that seem to alter the negative vertical gradient of the water vapor mixing ratio within the SBL: the presence of an intrusion and the possible stratification of the SBL based on different degrees of stability.

Vertical profiles of black carbon measured by a micro-aethalometer in summer in the North China Plain

Directory of Open Access Journals (Sweden)

L. Ran

2016-08-01

Full Text Available Black carbon (BC is a dominant absorber in the visible spectrum and a potent factor in climatic effects. Vertical profiles of BC were measured using a micro-aethalometer attached to a tethered balloon during the Vertical Observations of trace Gases and Aerosols (VOGA field campaign, in summer 2014 at a semirural site in the North China Plain (NCP. The diurnal cycle of BC vertical distributions following the evolution of the mixing layer (ML was investigated for the first time in the NCP region. Statistical parameters including identified mixing height (Hm and average BC mass concentrations within the ML (Cm and in the free troposphere (Cf were obtained for a selected dataset of 67 vertical profiles. Hm was usually lower than 0.2 km in the early morning and rapidly rose thereafter due to strengthened turbulence. The maximum height of the ML was reached in the late afternoon. The top of a full developed ML exceeded 1 km on sunny days in summer, while it stayed much lower on cloudy  days. The sunset triggered the collapse of the ML, and a stable nocturnal boundary layer (NBL gradually formed. Accordingly, the highest level Cm was found in the early morning and the lowest was found in the afternoon. In the daytime, BC was almost uniformly distributed within the ML and significantly decreased above the ML. During the field campaign, Cm averaged about 5.16 ± 2.49 µg m−3, with a range of 1.12 to 14.49 µg m−3, comparable with observational results in many polluted urban areas such as Milan in Italy and Shanghai in China. As evening approached, BC gradually built up near the surface and exponentially declined with height. In contrast to the large variability found both in Hm and Cm, Cf stayed relatively unaffected through the day. Cf was less than 10 % of the ground level under clean conditions, while it amounted to half of the ground level in some polluted cases. In situ measurements of BC vertical profiles would hopefully

Water velocity meter

Science.gov (United States)

Roberts, C. W.; Smith, D. L.

1970-01-01

Simple, inexpensive drag sphere velocity meter with a zero to 6 ft/sec range measures steady-state flow. When combined with appropriate data acquisition system, it is suited to applications where large numbers of simultaneous measurements are needed for current mapping or velocity profile determination.

Characterization of the slug flow formation in vertical-to-horizontal channels with obstructions

International Nuclear Information System (INIS)

Onder, E.N.

2004-01-01

This thesis presents the results of the work carried out to study the formation of slugs under conditions of vertical-to-horizontal counter-current flow with obstructions. A flow instability is the mechanism proposed for the formation of slugs in a co-current flow. However, to the best of author's knowledge no work has been carried out for the formation of slugs in a vertical-to-horizontal counter-current flow with obstructions. Despite the existence of a few studies on counter-current vertical-to-horizontal slug flow with obstructions, it is in particular of great importance in the area of nuclear reactor safety analysis of a CANDU reactor. A test section manufactured of 63.5 mm inner diameter (ID) plexiglass was used for this work. The test section consists of 2022 mm long vertical and 3327 mm long horizontal legs connected by a 90 o PVC elbow. The horizontal leg contains flanges in which an orifice may be installed. These flanges are located at the distance of 1110 mm and 2217 mm from the elbow. The experiments were carried out to study the frequency of the formation of slugs, the slug propagation velocity and the averaged void fraction of slugs. We also carried out experiments for the characterisation of the propagation of waves. This allowed us to obtain the initial conditions required by the present model in order to predict the formation of slugs. In this model, the initial profile of waves was used to start calculations. Therefore, the aim of these experiments was to obtain the initial profile of these waves. The comparison of the experimental data collected at the onset of flooding with that collected at the onset of slugging shows that the results are very close to each other. This reflects the fact that flooding is simultaneously accompanied by the formation of slugs in the horizontal leg. We found that, for a given liquid flow rate, the gas flow rate, necessary to form the slugs as well as to provoke flooding, decreases as the severity of the

Comparison of the GOSAT TANSO-FTS TIR CH volume mixing ratio vertical profiles with those measured by ACE-FTS, ESA MIPAS, IMK-IAA MIPAS, and 16 NDACC stations

Directory of Open Access Journals (Sweden)

K. S. Olsen

2017-10-01

Full Text Available The primary instrument on the Greenhouse gases Observing SATellite (GOSAT is the Thermal And Near infrared Sensor for carbon Observations (TANSO Fourier transform spectrometer (FTS. TANSO-FTS uses three short-wave infrared (SWIR bands to retrieve total columns of CO2 and CH4 along its optical line of sight and one thermal infrared (TIR channel to retrieve vertical profiles of CO2 and CH4 volume mixing ratios (VMRs in the troposphere. We examine version 1 of the TANSO-FTS TIR CH4 product by comparing co-located CH4 VMR vertical profiles from two other remote-sensing FTS systems: the Canadian Space Agency's Atmospheric Chemistry Experiment FTS (ACE-FTS on SCISAT (version 3.5 and the European Space Agency's Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat (ESA ML2PP version 6 and IMK-IAA reduced-resolution version V5R_CH4_224/225, as well as 16 ground stations with the Network for the Detection of Atmospheric Composition Change (NDACC. This work follows an initial inter-comparison study over the Arctic, which incorporated a ground-based FTS at the Polar Environment Atmospheric Research Laboratory (PEARL at Eureka, Canada, and focuses on tropospheric and lower-stratospheric measurements made at middle and tropical latitudes between 2009 and 2013 (mid-2012 for MIPAS. For comparison, vertical profiles from all instruments are interpolated onto a common pressure grid, and smoothing is applied to ACE-FTS, MIPAS, and NDACC vertical profiles. Smoothing is needed to account for differences between the vertical resolution of each instrument and differences in the dependence on a priori profiles. The smoothing operators use the TANSO-FTS a priori and averaging kernels in all cases. We present zonally averaged mean CH4 differences between each instrument and TANSO-FTS with and without smoothing, and we examine their information content, their sensitive altitude range, their correlation, their a priori dependence, and the

Application of vertical advection-diffusion model for studying CO2 and O2 profiles in central Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

AnilKumar, N.; Singbal, S.Y.S.

The vertical advection-diffusion model proposed by Craig has been applied to the study of CO sub(2) and O sub(2) profiles in Central Arabian Sea. Distributions of total CO Sub(2) and O sub(2) are explained better by expressions involving exponential...

Evolution of the two-phase flow in a vertical tube-decomposition of gas fraction profiles according to bubble size classes using wire-mesh sensors

Energy Technology Data Exchange (ETDEWEB)

Prasser, H.M.; Krepper, E.; Lucas, D. [Forschungszentrum Rossendorf e.V., Dresden (Germany)

2002-01-01

The wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of instantaneous gas fraction distributions in a cross section with a time resolution of 1200 frames per second and a spatial resolution of about 2-3 mm. At moderate flow velocities (up to 1-2 m.s{sup -1}), bubble size distributions can be obtained, since each individual bubble is mapped in several successive distributions. The method was used to study the evolution of the bubble size distribution in a vertical two-phase flow. For this purpose, the sensor was placed downstream of an air injector, the distance between air injection and sensor was varied. The bubble identification algorithm allows to select bubbles of a given range of the effective diameter and to calculate partial gas fraction profiles for this diameter range. In this way, the different behaviour of small and large bubbles in respect to the action of the lift force was observed in a mixture of small and large bubbles. (authors)

The turbulent mean-velocity profile: it is all in the spectrum

Science.gov (United States)

Gioia, Gustavo; Guttenberg, Nicholas; Goldenfeld, Nigel; Chakraborty, Pinaki

2010-11-01

It has long been surmised that the mean-velocity profile (MVP) of a pipe flow is closely related to the spectrum of turbulent energy. Here we perform a spectral analysis to identify the eddies that dominate the production of shear stress via momentum transfer. This analysis allows us to express the MVP as a functional of the spectrum. Each part of the MVP relates to a specific spectral range: the buffer layer to the dissipative range, the log layer to the inertial range, and the wake to the energetic range. The parameters of the spectrum set the thickness of the viscous layer, the amplitude of the buffer layer, and the amplitude of the wake.

Measurement of the wetting profile in concrete samples with vertical water by gamma radiation transmission method

International Nuclear Information System (INIS)

Silva, L.M. da; Rocha, M.C. da; Appoloni, C.R.; Portezan Filho, O.; Lopes, F.; Melquiades, F.L.; Santos, E.A. dos; Santos, A.O. dos; Moreira, A.C.; Poetker, W.E.; Almeida, E. de; Tannous, C.Q.; Kuramoto, R.; Cavalcante, F.H. de M.; Barbieri, P.F.

2000-01-01

Samples of concrete for popular habitation (0,1x0,03x0,1 m) and cellular concrete (0,1x0,05x0,1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137 Cs (3,7x10 10 Bq, 0662 MeV) source, NaI (Tl) of 2x2' detector coupled to between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. (author)

Modeling of radial gas fraction profiles for bubble flow in vertical pipes

Energy Technology Data Exchange (ETDEWEB)

Lucas, D.; Krepper, E.; Prasser, H.-M. [Forschungszentrum Rossendorf e.V., Institute of Safety Research, Dresden (Germany)

2001-07-01

The paper presents a method for the prediction of radial gas fraction profiles from a given bubble size distribution. The method is based on the assumption of the equilibrium of the forces acting on a bubble perpendicularly to the flow direction. Assuming a large number of bubble size classes radial distributions are calculated separately for all bubble classes. The sum of these distributions is the radial profile of the gas fraction. The results of the model are compared with experimental data for a number of gas and liquid volume flow rates. The experiments were performed at a vertical test loop (inner diameter 50 mm) in FZ-Rossendorf using a wire mesh sensor. The sensor enables the determination of void distributions in the cross section of the loop. A special evaluation procedure supplies bubble size distributions as well as local distributions of bubbles within a predefined interval of bubble sizes. There is a good agreement between experimental and calculated data. In particular the change from wall peaking to core peaking is well predicted. (authors)

Modeling of radial gas fraction profiles for bubble flow in vertical pipes

International Nuclear Information System (INIS)

Lucas, D.; Krepper, E.; Prasser, H.-M.

2001-01-01

The paper presents a method for the prediction of radial gas fraction profiles from a given bubble size distribution. The method is based on the assumption of the equilibrium of the forces acting on a bubble perpendicularly to the flow direction. Assuming a large number of bubble size classes radial distributions are calculated separately for all bubble classes. The sum of these distributions is the radial profile of the gas fraction. The results of the model are compared with experimental data for a number of gas and liquid volume flow rates. The experiments were performed at a vertical test loop (inner diameter 50 mm) in FZ-Rossendorf using a wire mesh sensor. The sensor enables the determination of void distributions in the cross section of the loop. A special evaluation procedure supplies bubble size distributions as well as local distributions of bubbles within a predefined interval of bubble sizes. There is a good agreement between experimental and calculated data. In particular the change from wall peaking to core peaking is well predicted. (authors)

Hip joint kinetics in the table tennis topspin forehand: relationship to racket velocity.

Science.gov (United States)

Iino, Yoichi

2018-04-01

The purpose of this study was to determine hip joint kinetics during a table tennis topspin forehand, and to investigate the relationship between the relevant kinematic and kinetic variables and the racket horizontal and vertical velocities at ball impact. Eighteen male advanced table tennis players hit cross-court topspin forehands against backspin balls. The hip joint torque and force components around the pelvis coordinate system were determined using inverse dynamics. Furthermore, the work done on the pelvis by these components was also determined. The peak pelvis axial rotation velocity and the work done by the playing side hip pelvis axial rotation torque were positively related to the racket horizontal velocity at impact. The sum of the work done on the pelvis by the backward tilt torques and the upward joint forces was positively related to the racket vertical velocity at impact. The results suggest that the playing side hip pelvis axial rotation torque exertion is important for acquiring a high racket horizontal velocity at impact. The pelvis backward tilt torques and upward joint forces at both hip joints collectively contribute to the generation of the racket vertical velocity, and the mechanism for acquiring the vertical velocity may vary among players.

The TEXT upgrade vertical interferometer

International Nuclear Information System (INIS)

Hallock, G.A.; Gartman, M.L.; Li, W.; Chiang, K.; Shin, S.; Castles, R.L.; Chatterjee, R.; Rahman, A.S.

1992-01-01

A far-infrared interferometer has been installed on TEXT upgrade to obtain electron density profiles. The primary system views the plasma vertically through a set of large (60-cm radialx7.62-cm toroidal) diagnostic ports. A 1-cm channel spacing (59 channels total) and fast electronic time response is used, to provide high resolution for radial profiles and perturbation experiments. Initial operation of the vertical system was obtained late in 1991, with six operating channels

Study on particle deposition in vertical square ventilation duct flows by different models

International Nuclear Information System (INIS)

Zhang Jinping; Li Angui

2008-01-01

A proper representation of the air flow in a ventilation duct is crucial for adequate prediction of the deposition velocity of particles. In this paper, the mean turbulent air flow fields are predicted by two different numerical models (the Reynolds stress transport model (RSM) and the realizable k-εmodel). Contours of mean streamwise velocity deduced from the k-ε model are compared with those obtained from the Reynolds stress transport model. Dimensionless deposition velocities of particles in downward and upward ventilation duct flows are also compared based on the flow fields presented by the two different numerical models. Trajectories of the particles are tracked using a one way coupling Lagrangian eddy-particle interaction model. Thousands of individual particles are released in the represented flow, and dimensionless deposition velocities are evaluated for the vertical walls in fully developed smooth vertical downward and upward square duct flows generated by the RSM and realizable k-ε model. The effects of particle diameter, dimensionless relaxation time, flow direction and air speed in vertical upward and downward square duct flows on the particle deposition velocities are discussed. The effects of lift and gravity on the particle deposition velocities are evaluated in vertical flows presented by the RSM. It is shown that the particle deposition velocities based on the RSM and realizable k-εmodel have subtle differences. The flow direction and the lift force significantly affect the particle deposition velocities in vertical duct flows. The simulation results are compared with earlier experimental data and the numerical results for fully developed duct flows. It is shown that the deposition velocities predicted are in agreement with the experimental data and the numerical results

The LISST-SL streamlined isokinetic suspended-sediment profiler

Science.gov (United States)

Gray, John R.; Agrawal, Yogesh C.; Pottsmith, H. Charles

2004-01-01

The new manually deployed Laser In Situ Scattering Transmissometer-StreamLined profiler (LISST-SL) represents a major technological advance for suspended-sediment measurements in rivers. The LISST-SL is being designed to provide real-time data on sediment concentrations and particle-size distributions. A pressure sensor and current meter provide real-time depth and ambient velocity data, respectively. The velocity data are also used to control pumpage across an internal laser so that the intake velocity is constantly adjusted to match the ambient stream velocity. Such isokinetic withdrawal is necessary for obtaining representative sedimentary measurements in streamflow, and ensures compliance with established practices. The velocity and sediment-concentration data are used to compute fluxes for up to 32 particle-size classes at points, verticals, or in the entire stream cross section. All data are stored internally, as well as transmitted via a 2-wire conductor to the operator using a specially developed communication protocol. The LISST-SL's performance will be measured and compared to published sedimentological accuracy criteria, and a performance summary will be placed on-line.

Multichannel analysis of surface-waves and integration of downhole acoustic televiewer imaging, ultrasonic Vs and Vp, and vertical seismic profiling in an NEHRP-standard classification, South of Concordia, Kansas, USA

Science.gov (United States)

Raef, Abdelmoneam; Gad, Sabreen; Tucker-Kulesza, Stacey

2015-10-01

Seismic site characteristics, as pertaining to earthquake hazard reduction, are a function of the subsurface elastic moduli and the geologic structures. This study explores how multiscale (surface, downhole, and laboratory) datasets can be utilized to improve "constrained" average Vs30 (shear-wave velocity to a 30-meter depth). We integrate borehole, surface and laboratory measurements for a seismic site classification based on the standards of the National Earthquake Hazard Reduction Program (NEHRP). The seismic shear-wave velocity (Vs30) was derived from a geophysical inversion workflow that utilized multichannel analysis of surface-waves (MASW) and downhole acoustic televiewer imaging (DATI). P-wave and S-wave velocities, based on laboratory measurements of arrival times of ultrasonic-frequency signals, supported the workflow by enabling us to calculate Poisson's ratio, which was incorporated in building an initial model for the geophysical inversion of MASW. Extraction of core samples from two boreholes provided lithology and thickness calibration of the amplitudes of the acoustic televiewer imaging for each layer. The MASW inversion, for calculating Vs sections, was constrained with both ultrasonic laboratory measurements (from first arrivals of Vs and Vp waveforms at simulated in situ overburden stress conditions) and the downhole acoustic televiewer (DATV) amplitude logs. The Vs30 calculations enabled categorizing the studied site as NEHRP-class "C" - very dense soil and soft rock. Unlike shallow fractured carbonates in the studied area, S-wave and P-wave velocities at ultrasonic frequency for the deeper intact shale core-samples from two boreholes were in better agreement with the corresponding velocities from both a zero-offset vertical seismic profiling (VSP) and inversion of Rayleigh-wave velocity dispersion curves.

Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

Energy Technology Data Exchange (ETDEWEB)

Rosenfeld, Daniel [Hebrew Univ. of Jerusalem (Israel)

2015-12-23

Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.

A Simple Method for Assessing Upper-Limb Force-Velocity Profile in Bench Press.

Science.gov (United States)

Rahmani, Abderrahmane; Samozino, Pierre; Morin, Jean-Benoit; Morel, Baptiste

2018-02-01

To analyze the reliability and validity of a field computation method based on easy-to-measure data to assess the mean force ([Formula: see text]) and velocity ([Formula: see text]) produced during a ballistic bench-press movement and to verify that the force-velocity profile (F-v) obtained with multiple loaded trials is accurately described. Twelve participants performed ballistic bench presses against various lifted mass from 30% to 70% of their body mass. For each trial, [Formula: see text] and [Formula: see text] were determined from an accelerometer (sampling rate 500 Hz; reference method) and a simple computation method based on upper-limb mass, barbell flight height, and push-off distance. These [Formula: see text] and [Formula: see text] data were used to establish the F-v relationship for each individual and method. A strong to almost perfect reliability was observed between the 2 trials (ICC > .90 for [Formula: see text] and .80 for [Formula: see text], CV%  .80, P push-off distance).

High Resolution Vertical Seismic Profile from the Chicxulub IODP/ICDP Expedition 364 Borehole: Wave Speeds and Seismic Reflectivity.

Science.gov (United States)

Nixon, C.; Kofman, R.; Schmitt, D. R.; Lofi, J.; Gulick, S. P. S.; Christeson, G. L.; Saustrup, S., Sr.; Morgan, J. V.

2017-12-01

We acquired a closely-spaced vertical seismic profile (VSP) in the Chicxulub K-Pg Impact Crater drilling program borehole to calibrate the existing surface seismic profiles and provide complementary measurements of in situ seismic wave speeds. Downhole seismic records were obtained at spacings ranging from 1.25 m to 5 m along the borehole from 47.5 m to 1325 mwsf (meters wireline below sea floor) (Fig 1a) using a Sercel SlimwaveTM geophone chain (University of Alberta). The seismic source was a 30/30ci Sercel Mini GI airgun (University of Texas), fired a minimum of 5 times per station. Seismic data processing used a combination of a commercial processing package (Schlumberger's VISTA) and MatlabTM codes. The VSP displays detailed reflectivity (Fig. 1a) with the strongest reflection seen at 600 mwsf (280 ms one-way time), geologically corresponding to the sharp contact between the post-impact sediments and the target peak ring rock, thus confirming the pre-drilling interpretations of the seismic profiles. A two-way time trace extracted from the separated up-going wavefield matches the major reflection both in travel time and character. In the granitic rocks that form the peak ring of the Chicxulub impact crater, we observe P-wave velocities of 4000-4500 m/s which are significantly less than the expected values of granitoids ( 6000 m/s) (Fig. 1b). The VSP measured wave speeds are confirmed against downhole sonic logging and in laboratory velocimetry measurements; these data provide additional evidence that the crustal material displaced by the impact experienced a significant amount of damage. Samples and data provided by IODP. Samples can be requested at http://web.iodp.tamu.edu/sdrm after 19 October 2017. Expedition 364 was jointly funded by ECORD, ICDP, and IODP with contributions and logistical support from the Yucatan State Government and UNAM. The downhole seismic chain and wireline system is funded by grants to DRS from the Canada Foundation for Innovation and

CFD modelling and validation of upward bubbly flow in an adiabatic vertical pipe using the quadrature method of moments

Energy Technology Data Exchange (ETDEWEB)

Peña-Monferrer, C., E-mail: cmonfer@upv.es [Institute for Energy Engineering, Universitat Politècnica de València, 46022 València (Spain); Passalacqua, A., E-mail: albertop@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Chiva, S., E-mail: schiva@emc.uji.es [Department of Mechanical Engineering and Construction, Universitat Jaume I, 12080 Castelló de la Plana (Spain); Muñoz-Cobo, J.L., E-mail: jlcobos@iqn.upv.es [Institute for Energy Engineering, Universitat Politècnica de València, 46022 València (Spain)

2016-05-15

Highlights: • A population balance equation solved with QMOM approximation is implemented in OpenFOAM. • Available models for interfacial forces and bubble induced turbulence are analyzed. • A vertical pipe flow is simulated for different bubbly flow conditions. • Two-phase flow characteristics in vertical pipes are properly predicted. - Abstract: An Eulerian–Eulerian approach was investigated to model adiabatic bubbly flow with CFD techniques. In the framework of the OpenFOAM{sup ®} software, a two-fluid model solver was modified to include a population balance equation, solved with the quadrature method of moments approximation to predict upward bubbly flow in vertical pipes considering the polydisperse nature of two-phase flow. Some progress have been made recently solving population balance equations in OpenFOAM{sup ®} and this research aims to extend its application to the case of vertical pipes under different conditions of liquid and gas velocities. In order to test the solver for nuclear applications, interfacial forces and bubble induced turbulence models were included to provide to this solver the capability to correctly predict the behavior of the continuous and disperse phases. Two-phase flow experiments with different superficial velocities of gas and liquid are used to validate the model and its implementation. Radial profiles of void fraction, gas and liquid velocities, Sauter mean diameter and turbulence intensity are compared to the computational results. These results are in satisfactory agreement with the experiments, showing the capability of the solver to predict two-phase flow characteristics.

Addendum: ``The Dynamics of M15: Observations of the Velocity Dispersion Profile and Fokker-Planck Models'' (ApJ, 481, 267 [1997])

Science.gov (United States)

Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.; Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.

2003-03-01

It has recently come to our attention that there are axis scale errors in three of the figures presented in Dull et al. (1997, hereafter D97). This paper presented Fokker-Planck models for the collapsed-core globular cluster M15 that include a dense, centrally concentrated population of neutron stars and massive white dwarfs. These models do not include a central black hole. Figure 12 of D97, which presents the predicted mass-to-light profile, is of particular interest, since it was used by Gerssen et al. (2002) as an input to their Jeans equation analysis of the Hubble Space Telescope (HST) STIS velocity measurements reported by van der Marel et al. (2002). On the basis of the original, incorrect version of Figure 12, Gerssen et al. (2002) concluded that the D97 models can fit the new data only with the addition of an intermediate-mass black hole. However, this is counter to our previous finding, shown in Figure 6 of D97, that the Fokker-Planck models predict the sort of moderately rising velocity dispersion profile that Gerssen et al. (2002) infer from the new data. Baumgardt et al. (2003) have independently noted this apparent inconsistency. We appreciate the thoughtful cooperation of Roeland van der Marel in resolving this issue. Using our corrected version of Figure 12 (see below), Gerssen et al. (2003) now find that the velocity dispersion profile that they infer from the D97 mass-to-light ratio profile is entirely consistent with the velocity dispersion profile presented in Figure 6 of D97. Gerssen et al. (2003) further find that there is no statistically significant difference between the fit to the van der Marel et al. (2002) velocity measurements provided by the D97 intermediate-phase model and that provided by their model, which supplements this D97 model with a 1.7+2.7-1.7×103Msolar black hole. Thus, the choice between models with and without black holes will require additional model predictions and observational tests. We present corrected versions of

Inventory and vertical migration of 137Cs in Spanish mainland soils

International Nuclear Information System (INIS)

Legarda, F.; Romero, L.M.; Herranz, M.; Barrera, M.; Idoeta, R.; Valino, F.; Olondo, C.; Caro, A.

2011-01-01

In this study the total activity of 137 Cs deposited per unit area over the Spanish peninsular territory was analysed using a 150 x 150 km 2 mesh grid, with samples taken from 29 points. The deposited activities ranged between 251 and 6074 Bq/m 2 . A linear relationship was obtained between these values and the mean annual rainfall at each sampling point which allowed a map to be drawn, using GIS software, which shows the distribution of total deposited 137 Cs activity across the Spanish mainland. At twelve of these sampling points the vertical migration profile of 137 Cs was obtained. These profiles are separated into two groups with different behaviour, one of which includes clay and loam soils and the other containing sandy soils. For both groups of profiles the parameters of the convective-diffusive model, which describes the vertical migration of 137 Cs in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) were calculated. - Highlights: → Measured the 137 Cs activity in Spanish mainland, being within a range of [251, 6074] Bq/m 2 , with a mean value of 1726 Bq/m 2 . → Establishment of the 137 Cs background by means of a 137 Cs inventory map showing its distribution in the Spanish mainland. → 137 Cs shows two different behaviour tendencies in soil depending on it. → The parameters which govern the applied model have been obtained for the analysed profiles. → Analysed those parameters, the two tendencies have been reflected in the obtained values.

Improving 1D Site Specific Velocity Profiles for the Kik-Net Network

Science.gov (United States)

Holt, James; Edwards, Benjamin; Pilz, Marco; Fäh, Donat; Rietbrock, Andreas

2017-04-01

Ground motion predication equations (GMPEs) form the cornerstone of modern seismic hazard assessments. When produced to a high standard they provide reliable estimates of ground motion/spectral acceleration for a given site and earthquake scenario. This information is crucial for engineers to optimise design and for regulators who enforce legal minimum safe design capacities. Classically, GMPEs were built upon the assumption that variability around the median model could be treated as aleatory. As understanding improved, it was noted that the propagation could be segregated into the response of the average path from the source and the response of the site. This is because the heterogeneity of the near-surface lithology is significantly different from that of the bulk path. It was then suggested that the semi-ergodic approach could be taken if the site response could be determined, moving uncertainty away from aleatory to epistemic. The determination of reliable site-specific response models is therefore becoming increasingly critical for ground motion models used in engineering practice. Today it is common practice to include proxies for site response within the scope of a GMPE, such as Vs30 or site classification, in an effort to reduce the overall uncertainty of the predication at a given site. However, these proxies are not always reliable enough to give confident ground motion estimates, due to the complexity of the near-surface. Other approaches of quantifying the response of the site include detailed numerical simulations (1/2/3D - linear, EQL, non-linear etc.). However, in order to be reliable, they require highly detailed and accurate velocity and, for non-linear analyses, material property models. It is possible to obtain this information through invasive methods, but is expensive, and not feasible for most projects. Here we propose an alternative method to derive reliable velocity profiles (and their uncertainty), calibrated using almost 20 years of

Entropy generation in natural convection in a symmetrically and uniformly heated vertical channel

Energy Technology Data Exchange (ETDEWEB)

Andreozzi, Assunta [Dipartimento di Energetica, Termofluidodinamica applicata e Condizionamenti ambientali, Universita degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Napoli (Italy); Auletta, Antonio [CIRA - Centro Italiano Ricerche Aerospaziali, Via Maiorise 1, 81043 Capua (CE) (Italy); Manca, Oronzio [Dipartimento di Ingegneria Aerospaziale e Meccanica, Seconda Universita degli Studi di Napoli, Real Casa dell' Annunziata, Via Roma 29, 81031 Aversa (CE) (Italy)

2006-08-15

In this study numerical predictions of local and global entropy generation rates in natural convection in air in a vertical channel symmetrically heated at uniform heat flux are reported. Results of entropy generation analysis are obtained by solving the entropy generation equation based on the velocity and temperature data. The analyzed regime is two-dimensional, laminar and steady state. The numerical procedure expands an existing computer code on natural convection in vertical channels. Results in terms of fields and profiles of local entropy generation, for various Rayleigh number, Ra, and aspect ratio values, L/b, are given. The distributions of local values show different behaviours for the different Ra values. A correlation between global entropy generation rates, Rayleigh number and aspect ratio is proposed in the ranges 10{sup 3}=

Inversely estimating the vertical profile of the soil CO2 production rate in a deciduous broadleaf forest using a particle filtering method.

Science.gov (United States)

Sakurai, Gen; Yonemura, Seiichiro; Kishimoto-Mo, Ayaka W; Murayama, Shohei; Ohtsuka, Toshiyuki; Yokozawa, Masayuki

2015-01-01

Carbon dioxide (CO2) efflux from the soil surface, which is a major source of CO2 from terrestrial ecosystems, represents the total CO2 production at all soil depths. Although many studies have estimated the vertical profile of the CO2 production rate, one of the difficulties in estimating the vertical profile is measuring diffusion coefficients of CO2 at all soil depths in a nondestructive manner. In this study, we estimated the temporal variation in the vertical profile of the CO2 production rate using a data assimilation method, the particle filtering method, in which the diffusion coefficients of CO2 were simultaneously estimated. The CO2 concentrations at several soil depths and CO2 efflux from the soil surface (only during the snow-free period) were measured at two points in a broadleaf forest in Japan, and the data were assimilated into a simple model including a diffusion equation. We found that there were large variations in the pattern of the vertical profile of the CO2 production rate between experiment sites: the peak CO2 production rate was at soil depths around 10 cm during the snow-free period at one site, but the peak was at the soil surface at the other site. Using this method to estimate the CO2 production rate during snow-cover periods allowed us to estimate CO2 efflux during that period as well. We estimated that the CO2 efflux during the snow-cover period (about half the year) accounted for around 13% of the annual CO2 efflux at this site. Although the method proposed in this study does not ensure the validity of the estimated diffusion coefficients and CO2 production rates, the method enables us to more closely approach the "actual" values by decreasing the variance of the posterior distribution of the values.

Characteristics of aerosol vertical profiles in Tsukuba, Japan, and their impacts on the evolution of the atmospheric boundary layer

Science.gov (United States)

Kudo, Rei; Aoyagi, Toshinori; Nishizawa, Tomoaki

2018-05-01

Vertical profiles of the aerosol physical and optical properties, with a focus on seasonal means and on transport events, were investigated in Tsukuba, Japan, by a synergistic remote sensing method that uses lidar and sky radiometer data. The retrieved aerosol vertical profiles of the springtime mean and five transport events were input to our developed one-dimensional atmospheric model, and the impacts of the aerosol vertical profiles on the evolution of the atmospheric boundary layer (ABL) were studied by numerical sensitivity experiments. The characteristics of the aerosol vertical profiles in Tsukuba are as follows: (1) the retrieval results in the spring showed that aerosol optical thickness at 532 nm in the free atmosphere (FA) was 0.13, greater than 0.08 in the ABL owing to the frequent occurrence of transported aerosols in the FA. In other seasons, optical thickness in the FA was almost the same as that in the ABL. (2) The aerosol optical and physical properties in the ABL showed a dependency on the extinction coefficient. With an increase in the extinction coefficient from 0.00 to 0.24 km-1, the Ångström exponent increased from 0.0 to 2.0, the single-scattering albedo increased from 0.87 to 0.99, and the asymmetry factor decreased from 0.75 to 0.50. (3) The large variability in the physical and optical properties of aerosols in the FA were attributed to transport events, during which the transported aerosols consisted of varying amounts of dust and smoke particles depending on where they originated (China, Mongolia, or Russia). The results of the numerical sensitivity experiments using the aerosol vertical profiles of the springtime mean and five transport events in the FA are as follows: (1) numerical sensitivity experiments based on simulations conducted with and without aerosols showed that aerosols caused the net downward radiation and the sensible and latent heat fluxes at the surface to decrease. The decrease in temperature in the ABL (-0.2 to -0

Programs to obtain vertical heights from mean sea level and for computing volume of sand/mineral along beaches:A case study with Kalbadevi beach profiling data and results.

Digital Repository Service at National Institute of Oceanography (India)

Ganesan, P.

vertical heights along profiles from M.S.L.? is given below: The reduced level over the bench mark pillar (BP:1 in this case, from where the profile starts) should be added with the first staff reading taken over it, which forms the height... of collimation (H.C.) of the instrument. From this H.C., all the successive staff readings (taken at regular distance interval, along the profile) should be deducted to get the vertical heights (called reduced level (R.L.) in survey terms). i) R...

Approaching space-time through velocity in doubly special relativity

International Nuclear Information System (INIS)

Aloisio, R.; Galante, A.; Grillo, A.F.; Luzio, E.; Mendez, F.

2004-01-01

We discuss the definition of velocity as dE/d vertical bar p vertical bar, where E, p are the energy and momentum of a particle, in doubly special relativity (DSR). If this definition matches dx/dt appropriate for the space-time sector, then space-time can in principle be built consistently with the existence of an invariant length scale. We show that, within different possible velocity definitions, a space-time compatible with momentum-space DSR principles cannot be derived

Shear-wave velocities beneath the Harrat Rahat volcanic field, Saudi Arabia, using ambient seismic noise analysis

Science.gov (United States)

Civilini, F.; Mooney, W.; Savage, M. K.; Townend, J.; Zahran, H. M.

2017-12-01

We present seismic shear-velocities for Harrat Rahat, a Cenozoic bimodal alkaline volcanic field in west-central Saudi Arabia, using seismic tomography from natural ambient noise. This project is part of an overall effort by the Saudi Geological Survey and the United States Geological Survey to describe the subsurface structure and assess hazards within the Saudi Arabian shield. Volcanism at Harrat Rahat began approximately 10 Ma, with at least three pulses around 10, 5, and 2 Ma, and at least several pulses in the Quaternary from 1.9 Ma to the present. This area is instrumented by 14 broadband Nanometrics Trillium T120 instruments across an array aperture of approximately 130 kilometers. We used a year of recorded natural ambient noise to determine group and phase velocity surface wave dispersion maps with a 0.1 decimal degree resolution for radial-radial, transverse-transverse, and vertical-vertical components of the empirical Green's function. A grid-search method was used to carry out 1D shear-velocity inversions at each latitude-longitude point and the results were interpolated to produce pseudo-3D shear velocity models. The dispersion maps resolved a zone of slow surface wave velocity south-east of the city of Medina spatially correlated with the 1256 CE eruption. A crustal layer interface at approximately 20 km depth was determined by the inversions for all components, matching the results of prior seismic-refraction studies. Cross-sections of the 3D shear velocity models were compared to gravity measurements obtained in the south-east edge of the field. We found that measurements of low gravity qualitatively correlate with low values of shear-velocity below 20 km along the cross-section profile. We apply these methods to obtain preliminary tomography results on the entire Arabian Shield.

Technical Note: Variance-covariance matrix and averaging kernels for the Levenberg-Marquardt solution of the retrieval of atmospheric vertical profiles

Directory of Open Access Journals (Sweden)

S. Ceccherini

2010-03-01

Full Text Available The variance-covariance matrix (VCM and the averaging kernel matrix (AKM are widely used tools to characterize atmospheric vertical profiles retrieved from remote sensing measurements. Accurate estimation of these quantities is essential for both the evaluation of the quality of the retrieved profiles and for the correct use of the profiles themselves in subsequent applications such as data comparison, data assimilation and data fusion. We propose a new method to estimate the VCM and AKM of vertical profiles retrieved using the Levenberg-Marquardt iterative technique. We apply the new method to the inversion of simulated limb emission measurements. Then we compare the obtained VCM and AKM with those resulting from other methods already published in the literature and with accurate estimates derived using statistical and numerical estimators. The proposed method accounts for all the iterations done in the inversion and provides the most accurate VCM and AKM. Furthermore, it correctly estimates the VCM and the AKM also if the retrieval iterations are stopped when a physically meaningful convergence criterion is fulfilled, i.e. before achievement of the numerical convergence at machine precision. The method can be easily implemented in any Levenberg-Marquardt iterative retrieval scheme, either constrained or unconstrained, without significant computational overhead.

Ground-Based Remote or In Situ Measurement of Vertical Profiles of Wind in the Lower Troposphere

Energy Technology Data Exchange (ETDEWEB)

Clifton, Andrew; Newman, Jennifer

2017-02-24

Knowledge of winds in the lower troposphere is essential for a range of applications, including weather forecasting, transportation, natural hazards, and wind energy. This presentation focuses on the measurement of vertical profiles of wind in the lower troposphere for wind energy applications. This presentation introduces the information that wind energy site development and operations require, how it used, and the benefits and problems of current measurements from in-situ measurements and remote sensing. The development of commercial Doppler wind lidar systems over the last 10 years are shown, along with the lessons learned from this experience. Finally, potential developments in wind profiling aimed at reducing uncertainty and increasing data availability are introduced.

SOMPROF: A vertically explicit soil organic matter model

NARCIS (Netherlands)

Braakhekke, M.C.; Beer, M.; Hoosbeek, M.R.; Kruijt, B.; Kabat, P.

2011-01-01

Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to

Total solar eclipse of 16 February 1980 and the vertical profiles of atmospheric parameters in the lowest 200M

Digital Repository Service at National Institute of Oceanography (India)

RameshBabu, V.; Sastry, J.S.

Vertical profiles of air temperature, wind and humidity at Raichur (16 degrees 12'N and 77 degrees 21'E) in the lowest 200m of the atmosphere are presented for the period 15-18 February 1980. The effect of the total solar eclipse, on 16 February...

A new software suite for NO2 vertical profile retrieval from ground-based zenith-sky spectrometers

International Nuclear Information System (INIS)

Denis, L.; Roscoe, H.K.; Chipperfield, M.P.; Roozendael, M. van; Goutail, F.

2005-01-01

Here we present an operational method to improve accuracy and information content of ground-based measurements of stratospheric NO 2 . The motive is to improve the investigation of trends in NO 2 , and is important because the current trend in NO 2 appears to contradict the trend in its source, suggesting that the stratospheric circulation has changed. To do so, a new software package for retrieving NO 2 vertical profiles from slant columns measured by zenith-sky spectrometers has been created. It uses a Rodgers optimal linear inverse method coupled with a radiative transfer model for calculations of transfer functions between profiles and columns, and a chemical box model for taking into account the NO 2 variations during twilight and during the day. Each model has parameters that vary according to season and location. Forerunners of each model have been previously validated. The scheme maps random errors in the measurements and systematic errors in the models and their parameters on to the retrieved profiles. Initialisation for models is derived from well-established climatologies. The software has been tested by comparing retrieved profiles to simultaneous balloon-borne profiles at mid-latitudes in spring

A look inside the San Andreas Fault at Parkfield through vertical seismic profiling.

Science.gov (United States)

Chavarria, J Andres; Malin, Peter; Catchings, Rufus D; Shalev, Eylon

2003-12-05

The San Andreas Fault Observatory at Depth pilot hole is located on the southwestern side of the Parkfield San Andreas fault. This observatory includes a vertical seismic profiling (VSP) array. VSP seismograms from nearby microearthquakes contain signals between the P and S waves. These signals may be P and S waves scattered by the local geologic structure. The collected scattering points form planar surfaces that we interpret as the San Andreas fault and four other secondary faults. The scattering process includes conversions between P and S waves, the strengths of which suggest large contrasts in material properties, possibly indicating the presence of cracks or fluids.

A fully consistent and conservative vertically adaptive coordinate system for SLIM 3D v0.4 with an application to the thermocline oscillations of Lake Tanganyika

Science.gov (United States)

Delandmeter, Philippe; Lambrechts, Jonathan; Legat, Vincent; Vallaeys, Valentin; Naithani, Jaya; Thiery, Wim; Remacle, Jean-François; Deleersnijder, Eric

2018-03-01

The discontinuous Galerkin (DG) finite element method is well suited for the modelling, with a relatively small number of elements, of three-dimensional flows exhibiting strong velocity or density gradients. Its performance can be highly enhanced by having recourse to r-adaptivity. Here, a vertical adaptive mesh method is developed for DG finite elements. This method, originally designed for finite difference schemes, is based on the vertical diffusion of the mesh nodes, with the diffusivity controlled by the density jumps at the mesh element interfaces. The mesh vertical movement is determined by means of a conservative arbitrary Lagrangian-Eulerian (ALE) formulation. Though conservativity is naturally achieved, tracer consistency is obtained by a suitable construction of the mesh vertical velocity field, which is defined in such a way that it is fully compatible with the tracer and continuity equations at a discrete level. The vertically adaptive mesh approach is implemented in the three-dimensional version of the geophysical and environmental flow Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM 3D; www.climate.be/slim). Idealised benchmarks, aimed at simulating the oscillations of a sharp thermocline, are dealt with. Then, the relevance of the vertical adaptivity technique is assessed by simulating thermocline oscillations of Lake Tanganyika. The results are compared to measured vertical profiles of temperature, showing similar stratification and outcropping events.

Vertical random variability of the distribution coefficient in the soil and its effect on the migration of fallout radionuclides

International Nuclear Information System (INIS)

Bunzl, K.

2002-01-01

In the field, the distribution coefficient, K d , for the sorption of a radionuclide by the soil cannot be expected to be constant. Even in a well defined soil horizon, K d will vary stochastically in horizontal as well as in vertical direction around a mean value. The horizontal random variability of K d produce a pronounced tailing effect in the concentration depth profile of a fallout radionuclide, much less is known on the corresponding effect of the vertical random variability. To analyze this effect theoretically, the classical convection-dispersion model in combination with the random-walk particle method was applied. The concentration depth profile of a radionuclide was calculated one year after deposition assuming constant values of the pore water velocity, the diffusion/dispersion coefficient, and the distribution coefficient (K d = 100 cm 3 x g -1 ) and exhibiting a vertical variability for K d according to a log-normal distribution with a geometric mean of 100 cm 3 x g -1 and a coefficient of variation of CV 0.53. The results show that these two concentration depth profiles are only slightly different, the location of the peak is shifted somewhat upwards, and the dispersion of the concentration depth profile is slightly larger. A substantial tailing effect of the concentration depth profile is not perceivable. Especially with respect to the location of the peak, a very good approximation of the concentration depth profile is obtained if the arithmetic mean of the K d -values (K d = 113 cm 3 x g -1 ) and a slightly increased dispersion coefficient are used in the analytical solution of the classical convection-dispersion equation with constant K d . The evaluation of the observed concentration depth profile with the analytical solution of the classical convection-dispersion equation with constant parameters will, within the usual experimental limits, hardly reveal the presence of a log-normal random distribution of K d in the vertical direction in

Comparison of index velocity measurements made with a horizontal acoustic Doppler current profiler

Science.gov (United States)

Jackson, P. Ryan; Johnson, Kevin K.; Duncker, James J.

2012-01-01

The State of Illinois' annual withdrawal from Lake Michigan is limited by a U.S. Supreme Court decree, and the U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Every 5 years, a technical review committee consisting of practicing engineers and academics is convened to review the U.S. Geological Survey's streamgage practices in the CSSC near Lemont, Illinois. The sixth technical review committee raised a number of questions concerning the flows and streamgage practices in the CSSC near Lemont and this report provides answers to many of those questions. In addition, it is the purpose of this report to examine the index velocity meters in use at Lemont and determine whether the acoustic velocity meter (AVM), which is now the primary index velocity meter, can be replaced by the horizontal acoustic Doppler current profiler (H-ADCP), which is currently the backup meter. Application of the AVM and H-ADCP to index velocity measurements in the CSSC near Lemont, Illinois, has produced good ratings to date. The site is well suited to index velocity measurements in spite of the large range of velocities and highly unsteady flows at the site. Flow variability arises from a range of sources: operation of the waterway through control structures, lockage-generated disturbances, commercial and recreational traffic, industrial withdrawals and discharges, natural inflows, seiches, and storm events. The influences of these factors on the index velocity measurements at Lemont is examined in detail in this report. Results of detailed data comparisons and flow analyses show that use of bank-mounted instrumentation such as the AVM and H-ADCP appears to be the best option for index velocity measurement in the CSSC near Lemont. Comparison of the rating curves for the AVM and H-ADCP demonstrates

Mitigating the negative impacts of tall wind turbines on bats: Vertical activity profiles and relationships to wind speed.

Science.gov (United States)

Wellig, Sascha D; Nusslé, Sébastien; Miltner, Daniela; Kohle, Oliver; Glaizot, Olivier; Braunisch, Veronika; Obrist, Martin K; Arlettaz, Raphaël

2018-01-01

Wind turbines represent a source of hazard for bats, especially through collision with rotor blades. With increasing technical development, tall turbines (rotor-swept zone 50-150 m above ground level) are becoming widespread, yet we lack quantitative information about species active at these heights, which impedes proposing targeted mitigation recommendations for bat-friendly turbine operation. We investigated vertical activity profiles of a bat assemblage, and their relationships to wind speed, within a major valley of the European Alps where tall wind turbines are being deployed. To monitor bat activity we installed automatic recorders at sequentially increasing heights from ground level up to 65 m, with the goal to determine species-specific vertical activity profiles and to link them to wind speed. Bat call sequences were analysed with an automatic algorithm, paying particular attention to mouse-eared bats (Myotis myotis and Myotis blythii) and the European free-tailed bat (Tadarida teniotis), three locally rare species. The most often recorded bats were the Common pipistrelle (Pipistrellus pipistrellus) and Savi's pipistrelle (Hypsugo savii). Mouse-eared bats were rarely recorded, and mostly just above ground, appearing out of risk of collision. T. teniotis had a more evenly distributed vertical activity profile, often being active at rotor level, but its activity at that height ceased above 5 ms-1 wind speed. Overall bat activity in the rotor-swept zone declined with increasing wind speed, dropping below 5% above 5.4 ms-1. Collision risk could be drastically reduced if nocturnal operation of tall wind turbines would be restricted to wind speeds above 5 ms-1. Such measure should be implemented year-round because T. teniotis remains active in winter. This operational restriction is likely to cause only small energy production losses at these tall wind turbines, although further analyses are needed to assess these losses precisely.

The Design of Ocean Turbulence Measurement with a Free Fall Vertical Profiler

Science.gov (United States)

Luan, Xin; Xin, Jia; Zhu, Tieyi; Yang, Hua; Teng, Yuru; Song, Dalei

2018-03-01

The newly designed instrument Free Fall Vertical Profiler (FFVP) developed by Ocean University of China (OUC) had been deployed in the Western Pacific in March 08, 2017 and succeed to collect turbulence signals about 350-m-deep water. According to the requirements of turbulence measurement, the mechanical design was developed for turbulence platform to achieve stability and good flow tracking. By analysing the Heading, Pitch and Roll, the results suggested that the platform satisfies the requirements of stability. The power spectrum of the cleaned shear signals using the noise correction algorithm match well with the theoretical Nasmyth spectrum and the rate of turbulence dissipation are approximately 10-8 W/kg. In general, the FFVP was rationally designed and provided a good measurement platform for turbulence observation.

Inventory and vertical migration of {sup 137}Cs in Spanish mainland soils

Energy Technology Data Exchange (ETDEWEB)

Legarda, F. [Dept. Nuclear Engineering and Fluid Mechanics, University of the Basque Country, Alda Urquijo, s/n, E-48013 Bilbao (Spain); Romero, L.M. [CIEMAT, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Av. Complutense 22, 28040 Madrid (Spain); Herranz, M. [Dept. Nuclear Engineering and Fluid Mechanics, University of the Basque Country, Alda Urquijo, s/n, E-48013 Bilbao (Spain); Barrera, M. [CIEMAT, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Av. Complutense 22, 28040 Madrid (Spain); Idoeta, R. [Dept. Nuclear Engineering and Fluid Mechanics, University of the Basque Country, Alda Urquijo, s/n, E-48013 Bilbao (Spain); Valino, F. [CIEMAT, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Av. Complutense 22, 28040 Madrid (Spain); Olondo, C., E-mail: kontxi.olondo@ehu.es [Dept. Nuclear Engineering and Fluid Mechanics, University of the Basque Country, Alda Urquijo, s/n, E-48013 Bilbao (Spain); Caro, A. [CIEMAT, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Av. Complutense 22, 28040 Madrid (Spain)

2011-06-15

In this study the total activity of {sup 137}Cs deposited per unit area over the Spanish peninsular territory was analysed using a 150 x 150 km{sup 2} mesh grid, with samples taken from 29 points. The deposited activities ranged between 251 and 6074 Bq/m{sup 2}. A linear relationship was obtained between these values and the mean annual rainfall at each sampling point which allowed a map to be drawn, using GIS software, which shows the distribution of total deposited {sup 137}Cs activity across the Spanish mainland. At twelve of these sampling points the vertical migration profile of {sup 137}Cs was obtained. These profiles are separated into two groups with different behaviour, one of which includes clay and loam soils and the other containing sandy soils. For both groups of profiles the parameters of the convective-diffusive model, which describes the vertical migration of {sup 137}Cs in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) were calculated. - Highlights: > Measured the {sup 137}Cs activity in Spanish mainland, being within a range of [251, 6074] Bq/m{sup 2}, with a mean value of 1726 Bq/m{sup 2}. > Establishment of the {sup 137}Cs background by means of a {sup 137}Cs inventory map showing its distribution in the Spanish mainland. > {sup 137}Cs shows two different behaviour tendencies in soil depending on it. > The parameters which govern the applied model have been obtained for the analysed profiles. > Analysed those parameters, the two tendencies have been reflected in the obtained values.

A Universal Velocity Dispersion Profile for Pressure Supported Systems: Evidence for MONDian Gravity across Seven Orders of Magnitude in Mass

Energy Technology Data Exchange (ETDEWEB)

Durazo, R.; Hernandez, X.; Sánchez, S. F. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264 C.P. 04510 México D.F., México (Mexico); Sodi, B. Cervantes [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

2017-03-10

For any MONDian extended theory of gravity where the rotation curves of spiral galaxies are explained through a change in physics rather than the hypothesis of dark matter, a generic dynamical behavior is expected for pressure supported systems: an outer flattening of the velocity dispersion profile occurring at a characteristic radius, where both the amplitude of this flat velocity dispersion and the radius at which it appears are predicted to show distinct scalings with the total mass of the system. By carefully analyzing the dynamics of globular clusters and elliptical galaxies, we are able to significantly extend the astronomical diversity of objects in which MONDian gravity has been tested, from spiral galaxies to the much larger mass range covered by pressure supported systems. We show that a universal projected velocity dispersion profile accurately describes various classes of pressure supported systems, and further, that the expectations of extended gravity are met across seven orders of magnitude in mass. These observed scalings are not expected under dark matter cosmology, and would require particular explanations tuned at the scales of each distinct astrophysical system.

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.

Measured and modelled concentrations and vertical profiles of airborne particulate matter within the boundary layer of a street canyon

International Nuclear Information System (INIS)

Colls, J.J.; Micallef, A.

1999-01-01

Concentrations and vertical profiles of various fractions of airborne particulate matter (suspended particulate matter (SPM), PM 10 and PM 2.5 ) have been measured over the first three metres from ground in a street canyon. Measurements were carried out using automated near real-time apparatus called the Kinetic Sequential Sampling (KSS) system. KSS system is essentially an electronically-controlled lift carrying a real-time particle monitor for sampling air sequentially, at different heights within the breathing zone, which includes all heights within the surface layer of a street canyon at which people may breathe. Data is automatically logged at the different receptor levels, for the determination of the average vertical concentration profile of airborne particulate matter. For measuring the airborne particle concentration, a Grimm Dust Monitor 1.104/5 was used. The recorded data also allows for time series analysis of airborne particulate matter concentration at different heights. Time series data and hourly-average vertical concentration profiles in the boundary layer of the confines of a street are thought to be mainly determined by traffic emissions and traffic associated processes. Hence the measured data were compared with results of a street canyon emission-dispersion model in time and space. This Street Level Air Quality (SLAQ) model employs the plume-box technique and includes modules for simulating vehicle-generated effects such as thermally- and mechanically-generated turbulence and resuspension of road dust. Environmental processes, such as turbulence resulting from surface sensible heat and the formation of sulphate aerosol from sulphur dioxide exhaust emissions, are taken into account. The paper presents an outline description of the measuring technique and model used, and a comparison of the measured and modelled data

Optimal Balance Between Force and Velocity Differs Among World-Class Athletes.

Science.gov (United States)

Giroux, Caroline; Rabita, Giuseppe; Chollet, Didier; Guilhem, Gaël

2016-02-01

Performance during human movements is highly related to force and velocity muscle capacities. Those capacities are highly developed in elite athletes practicing power-oriented sports. However, it is still unclear whether the balance between their force and velocity-generating capacities constitutes an optimal profile. In this study, we aimed to determine the effect of elite sport background on the force-velocity relationship in the squat jump, and evaluate the level of optimization of these profiles. Ninety-five elite athletes in cycling, fencing, taekwondo, and athletic sprinting, and 15 control participants performed squat jumps in 7 loading conditions (range: 0%-60% of the maximal load they were able to lift). Theoretical maximal power (Pm), force (F0), and velocity (v0) were determined from the individual force-velocity relationships. Optimal profiles were assessed by calculating the optimal force (F0th) and velocity (v0th). Athletic sprinters and cyclists produced greater force than the other groups (P balanced force-velocity profiles. Moreover, the differences between measured and optimal force-velocity profiles raise potential sources of performance improvement in elite athletes.

High-Latitude Topside Ionospheric Vertical Electron-Density-Profile Changes in Response to Large Magnetic Storms

Science.gov (United States)

Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

2015-01-01

Large magnetic-storm induced changes have been detected in high-latitude topside vertical electron-density profiles Ne(h). The investigation was based on the large database of topside Ne(h) profiles and digital topside ionograms from the International Satellites for Ionospheric Studies (ISIS) program available from the NASA Space Physics Data Facility (SPDF) at http://spdf.gsfc.nasa.gov/isis/isis-status.html. This large database enabled Ne(h) profiles to be obtained when an ISIS satellite passed through nearly the same region of space before, during, and after a major magnetic storm. A major goal was to relate the magnetic-storm induced high-latitude Ne(h) profile changes to solar-wind parameters. Thus an additional data constraint was to consider only storms where solar-wind data were available from the NASA/SPDF OMNIWeb database. Ten large magnetic storms (with Dst less than -100 nT) were identified that satisfied both the Ne(h) profile and the solar-wind data constraints. During five of these storms topside ionospheric Ne(h) profiles were available in the high-latitude northern hemisphere and during the other five storms similar ionospheric data were available in the southern hemisphere. Large Ne(h) changes were observed during each one of these storms. Our concentration in this paper is on the northern hemisphere. The data coverage was best for the northern-hemisphere winter. Here Ne(h) profile enhancements were always observed when the magnetic local time (MLT) was between 00 and 03 and Ne(h) profile depletions were always observed between 08 and 10 MLT. The observed Ne(h) deviations were compared with solar-wind parameters, with appropriate time shifts, for four storms.

Experimental Study on The Two-Phase Flow Characteristics Using Conductivity Probes And Laser Doppler Anemometry In A Vertical Pipe

Science.gov (United States)

Chiva, S.; Mendez, S.; Muñoz-Cobo, J. L.; Julia, J. E.; Hernandez, L.

2007-06-01

An upward isothermal co-current air-water flow in a vertical pipe (50.2 mm inner diameter) has been experimental investigated. Local measurements of void fraction, interfacial area concentration (IAC), interfacial velocity and Sauter mean diameter were measured using a double sensor conductivity probe. Liquid velocity and turbulence intensity were measured using Laser Doppler Anemometry (LDA). Different air-water flow configurations was investigated for a liquid flow rate ranged from 0.491 m/s to 0.981 m/s and a void fraction up to 10 %. For each two-phase flow configuration twenty five radial position and three axial locations were measured by the conductivity probe methodology, and several radial profiles was measured with LDA at different axial positions.

Seismic Technology Adapted to Analyzing and Developing Geothermal Systems Below Surface-Exposed High-Velocity Rocks Final Report

Energy Technology Data Exchange (ETDEWEB)

Hardage, Bob A. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; DeAngelo, Michael V. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Ermolaeva, Elena [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Hardage, Bob A. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Remington, Randy [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Sava, Diana [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Wagner, Donald [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Wei, Shuijion [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology

2013-02-01

The objective of our research was to develop and demonstrate seismic data-acquisition and data-processing technologies that allow geothermal prospects below high-velocity rock outcrops to be evaluated. To do this, we acquired a 3-component seismic test line across an area of exposed high-velocity rocks in Brewster County, Texas, where there is high heat flow and surface conditions mimic those found at numerous geothermal prospects. Seismic contractors have not succeeded in creating good-quality seismic data in this area for companies who have acquired data for oil and gas exploitation purposes. Our test profile traversed an area where high-velocity rocks and low-velocity sediment were exposed on the surface in alternating patterns that repeated along the test line. We verified that these surface conditions cause non-ending reverberations of Love waves, Rayleigh waves, and shallow critical refractions to travel across the earth surface between the boundaries of the fast-velocity and slow-velocity material exposed on the surface. These reverberating surface waves form the high level of noise in this area that does not allow reflections from deep interfaces to be seen and utilized. Our data-acquisition method of deploying a box array of closely spaced geophones allowed us to recognize and evaluate these surface-wave noise modes regardless of the azimuth direction to the surface anomaly that backscattered the waves and caused them to return to the test-line profile. With this knowledge of the surface-wave noise, we were able to process these test-line data to create P-P and SH-SH images that were superior to those produced by a skilled seismic data-processing contractor. Compared to the P-P data acquired along the test line, the SH-SH data provided a better detection of faults and could be used to trace these faults upward to the boundaries of exposed surface rocks. We expanded our comparison of the relative value of S-wave and P-wave seismic data for geothermal

Airborne in situ vertical profiling of HDO / H216O in the subtropical troposphere during the MUSICA remote sensing validation campaign

Science.gov (United States)

Dyroff, C.; Sanati, S.; Christner, E.; Zahn, A.; Balzer, M.; Bouquet, H.; McManus, J. B.; Gonzalez-Ramos, Y.; Schneider, M.

2015-05-01

Vertical profiles of water vapor (H2O) and its isotope ratio D / H expressed as δD(H2O) were measured in situ by the ISOWAT II diode-laser spectrometer during the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA) airborne campaign. We present recent modifications of the instrument design. The instrument calibration on the ground as well as in flight is described. Based on the calibration measurements, the humidity-dependent uncertainty of our airborne data is determined. For the majority of the airborne data we achieved an accuracy (uncertainty of the mean) of Δ(δD) ≈10‰. Vertical profiles between 150 and ~7000 m were obtained during 7 days in July and August 2013 over the subtropical North Atlantic Ocean near Tenerife. The flights were coordinated with ground-based (Network for the Detection of Atmospheric Composition Change, NDACC) and space-based (Infrared Atmospheric Sounding Interferometer, IASI) FTIR remote sensing measurements of δD(H2O) as a means to validate the remote sensing humidity and δD(H2O) data products. The results of the validation are presented in detail in a separate paper (Schneider et al., 2014). The profiles were obtained with a high vertical resolution of around 3 m. By analyzing humidity and δD(H2O) correlations we were able to identify different layers of air masses with specific isotopic signatures. The results are discussed.

Investigation of vertical slug flow with advanced two-phase flow instrumentation

International Nuclear Information System (INIS)

Mi, Y.; Ishii, M.; Tsoukalas, L.H.

2001-01-01

Extensive experiments of vertical slug flow were carried out with an electromagnetic flowmeter and an impedance void-meter in an air-water two-phase experimental loop. The basic principles of these instruments in vertical slug flow measurements are discussed. Time series of the liquid velocity and the impedance were separated into two parts corresponding to the Taylor bubble and the liquid slug. Characteristics of slug flow, such as the void fractions, probabilities and lengths of the Taylor bubble and liquid slug, slug unit velocity, area-averaged liquid velocity, and liquid film velocity of the Taylor bubble tail, etc., were obtained. For the first time, the area-averaged liquid velocity of slug flow was revealed by the electromagnetic flowmeter. It is realized that the void fraction of the liquid slug is determined by the turbulent intensity due to the relative liquid motion between the Taylor bubble tail region and its wake region. A correlation of the void fraction of the liquid slug is developed based on experimental results obtained from a test section with 50.8 mm i.d. The results of this study suggest a promising improvement in understanding of vertical slug flow

Study of Variable Turbulent Prandtl Number Model for Heat Transfer to Supercritical Fluids in Vertical Tubes

Science.gov (United States)

Tian, Ran; Dai, Xiaoye; Wang, Dabiao; Shi, Lin

2018-06-01

In order to improve the prediction performance of the numerical simulations for heat transfer of supercritical pressure fluids, a variable turbulent Prandtl number (Prt) model for vertical upward flow at supercritical pressures was developed in this study. The effects of Prt on the numerical simulation were analyzed, especially for the heat transfer deterioration conditions. Based on the analyses, the turbulent Prandtl number was modeled as a function of the turbulent viscosity ratio and molecular Prandtl number. The model was evaluated using experimental heat transfer data of CO2, water and Freon. The wall temperatures, including the heat transfer deterioration cases, were more accurately predicted by this model than by traditional numerical calculations with a constant Prt. By analyzing the predicted results with and without the variable Prt model, it was found that the predicted velocity distribution and turbulent mixing characteristics with the variable Prt model are quite different from that predicted by a constant Prt. When heat transfer deterioration occurs, the radial velocity profile deviates from the log-law profile and the restrained turbulent mixing then leads to the deteriorated heat transfer.

Light hydrocarbons vertical profiles and fluxes in a french rural area

Science.gov (United States)

Kanakidou, M.; Bonsang, B.; Lambert, G.

By means of manned hot air balloon flights, in July 1986, an experiment was conducted in a rural area of southwest France in order to determine the production at ground level of non-methane hydrocarbons in the C 2-C 6 range. Flux determinations were based on vertical profiles before and after the development of a temperature inversion layer which allowed the measurement of the NMHC accumulation close to ground level. The main species produced in the late afternoon were acetylene, propane, ethene, propene and ethane with production rates of the order of 0.5 to 2 × 10 -4g of C m -2 h -1. Isoprene was found to be the main other unsaturated species also produced. The fluxes and the atmospheric content of the air column before the inversion are consistent with an average OH radical concentration of 2 × 10 6 cm -3.

Rain cell-based identification of the vertical profile of reflectivity as observed by weather radar and its use for precipitation uncertainty estimation

Science.gov (United States)

Hazenberg, P.; Torfs, P. J. J. F.; Leijnse, H.; Uijlenhoet, R.

2012-04-01

The wide scale implementation of weather radar systems over the last couple of decades has increased our understanding concerning spatio-temporal precipitation dynamics. However, the quantitative estimation of precipitation by these devices is affected by many sources of error. A very dominant source of error results from vertical variations in the hydrometeor size distribution known as the vertical profile of reflectivity (VPR). Since the height of the measurement as well as the beam volume increases with distance from the radar, for stratiform precipitation this results in a serious underestimation (overestimation) of the surface reflectivity while sampling within the snow (bright band) region. This research presents a precipitation cell-based implementation to correct volumetric weather radar measurements for VPR effects. Using the properties of a flipping carpenter square, a contour-based identification technique was developed, which is able to identify and track precipitation cells in real time, distinguishing between convective, stratiform and undefined precipitation. For the latter two types of systems, for each individual cell, a physically plausible vertical profile of reflectivity is estimated using a Monte Carlo optimization method. Since it can be expected that the VPR will vary within a given precipitation cell, a method was developed to take the uncertainty of the VPR estimate into account. As a result, we are able to estimate the amount of precipitation uncertainty as observed by weather radar due to VPR for a given precipitation type and storm cell. We demonstrate the possibilities of this technique for a number of winter precipitation systems observed within the Belgian Ardennes. For these systems, in general, the precipitation uncertainty estimate due to vertical reflectivity profile variations varies between 10-40%.

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds.

Science.gov (United States)

Miller, Daniel J; Zhang, Zhibo; Ackerman, Andrew S; Platnick, Steven; Baum, Bryan A

2016-04-27

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness ( τ ) and effective radius ( r e ) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5-10 g/m 2 . In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic r e profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques.

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds

Science.gov (United States)

Miller, Daniel J.; Zhang, Zhibo; Ackerman, Andrew S.; Platnick, Steven; Baum, Bryan A.

2018-01-01

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness (τ) and effective radius (re) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5–10 g/m2. In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic re profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques. PMID:29637042

Referencing geostrophic velocities using ADCP data Referencing geostrophic velocities using ADCP data

Directory of Open Access Journals (Sweden)

Isis Comas-Rodríguez

2010-06-01

Full Text Available Acoustic Doppler Current Profilers (ADCPs have proven to be a useful oceanographic tool in the study of ocean dynamics. Data from D279, a transatlantic hydrographic cruise carried out in spring 2004 along 24.5°N, were processed, and lowered ADCP (LADCP bottom track data were used to assess the choice of reference velocity for geostrophic calculations. The reference velocities from different combinations of ADCP data were compared to one another and a reference velocity was chosen based on the LADCP data. The barotropic tidal component was subtracted to provide a final reference velocity estimated by LADCP data. The results of the velocity fields are also shown. Further studies involving inverse solutions will include the reference velocity calculated here.

A multi-model analysis of vertical ozone profiles

Directory of Open Access Journals (Sweden)

J. E. Jonson

2010-06-01

Full Text Available A multi-model study of the long-range transport of ozone and its precursors from major anthropogenic source regions was coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP under the Convention on Long-range Transboundary Air Pollution (LRTAP. Vertical profiles of ozone at 12-h intervals from 2001 are available from twelve of the models contributing to this study and are compared here with observed profiles from ozonesondes. The contributions from each major source region are analysed for selected sondes, and this analysis is supplemented by retroplume calculations using the FLEXPART Lagrangian particle dispersion model to provide insight into the origin of ozone transport events and the cause of differences between the models and observations.

In the boundary layer ozone levels are in general strongly affected by regional sources and sinks. With a considerably longer lifetime in the free troposphere, ozone here is to a much larger extent affected by processes on a larger scale such as intercontinental transport and exchange with the stratosphere. Such individual events are difficult to trace over several days or weeks of transport. This may explain why statistical relationships between models and ozonesonde measurements are far less satisfactory than shown in previous studies for surface measurements at all seasons. The lowest bias between model-calculated ozone profiles and the ozonesonde measurements is seen in the winter and autumn months. Following the increase in photochemical activity in the spring and summer months, the spread in model results increases, and the agreement between ozonesonde measurements and the individual models deteriorates further.

At selected sites calculated contributions to ozone levels in the free troposphere from intercontinental transport are shown. Intercontinental transport is identified based on differences in model calculations with unperturbed emissions and

LIMS/Nimbus-7 Level 2 Vertical Profiles of O3, NO2, H2O, HNO3, Geopotential Height, and Temperature V006

Data.gov (United States)

National Aeronautics and Space Administration — The Limb Infrared Monitor of the Stratosphere (LIMS) version 6 Level-2 data product consists of daily, geolocated, vertical profiles of temperature, geopotential...

Muscle Force-Velocity Relationships Observed in Four Different Functional Tests.

Science.gov (United States)

Zivkovic, Milena Z; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan

2017-02-01

The aims of the present study were to investigate the shape and strength of the force-velocity relationships observed in different functional movement tests and explore the parameters depicting force, velocity and power producing capacities of the tested muscles. Twelve subjects were tested on maximum performance in vertical jumps, cycling, bench press throws, and bench pulls performed against different loads. Thereafter, both the averaged and maximum force and velocity variables recorded from individual trials were used for force-velocity relationship modeling. The observed individual force-velocity relationships were exceptionally strong (median correlation coefficients ranged from r = 0.930 to r = 0.995) and approximately linear independently of the test and variable type. Most of the relationship parameters observed from the averaged and maximum force and velocity variable types were strongly related in all tests (r = 0.789-0.991), except for those in vertical jumps (r = 0.485-0.930). However, the generalizability of the force-velocity relationship parameters depicting maximum force, velocity and power of the tested muscles across different tests was inconsistent and on average moderate. We concluded that the linear force-velocity relationship model based on either maximum or averaged force-velocity data could provide the outcomes depicting force, velocity and power generating capacity of the tested muscles, although such outcomes can only be partially generalized across different muscles.

A new software suite for NO{sub 2} vertical profile retrieval from ground-based zenith-sky spectrometers

Energy Technology Data Exchange (ETDEWEB)

Denis, L. [British Antarctic Survey/NERC, Madingley Road, Cambridge CB3 0ET (United Kingdom); Roscoe, H.K. [British Antarctic Survey/NERC, Madingley Road, Cambridge CB3 0ET (United Kingdom)]. E-mail: h.roscoe@bas.ac.uk; Chipperfield, M.P. [Environment Centre, University of Leeds, Leeds LS2 9JT (United Kingdom); Roozendael, M. van [Belgian Institute for Space Aeronomy (BIRA/IASB), 1180 Brussels (Belgium); Goutail, F. [Service d' Aeronomie du CNRS, BP3, 91271 Verrieres le Buisson (France)

2005-05-15

Here we present an operational method to improve accuracy and information content of ground-based measurements of stratospheric NO{sub 2}. The motive is to improve the investigation of trends in NO{sub 2}, and is important because the current trend in NO{sub 2} appears to contradict the trend in its source, suggesting that the stratospheric circulation has changed. To do so, a new software package for retrieving NO{sub 2} vertical profiles from slant columns measured by zenith-sky spectrometers has been created. It uses a Rodgers optimal linear inverse method coupled with a radiative transfer model for calculations of transfer functions between profiles and columns, and a chemical box model for taking into account the NO{sub 2} variations during twilight and during the day. Each model has parameters that vary according to season and location. Forerunners of each model have been previously validated. The scheme maps random errors in the measurements and systematic errors in the models and their parameters on to the retrieved profiles. Initialisation for models is derived from well-established climatologies. The software has been tested by comparing retrieved profiles to simultaneous balloon-borne profiles at mid-latitudes in spring.

Validation of the iPhone app using the force platform to estimate vertical jump height.

Science.gov (United States)

Carlos-Vivas, Jorge; Martin-Martinez, Juan P; Hernandez-Mocholi, Miguel A; Perez-Gomez, Jorge

2018-03-01

Vertical jump performance has been evaluated with several devices: force platforms, contact mats, Vertec, accelerometers, infrared cameras and high-velocity cameras; however, the force platform is considered the gold standard for measuring vertical jump height. The purpose of this study was to validate an iPhone app called My Jump, that measures vertical jump height by comparing it with other methods that use the force platform to estimate vertical jump height, namely, vertical velocity at take-off and time in the air. A total of 40 sport sciences students (age 21.4±1.9 years) completed five countermovement jumps (CMJs) over a force platform. Thus, 200 CMJ heights were evaluated from the vertical velocity at take-off and the time in the air using the force platform, and from the time in the air with the My Jump mobile application. The height obtained was compared using the intraclass correlation coefficient (ICC). Correlation between APP and force platform using the time in the air was perfect (ICC=1.000, PJump, is an appropriate method to evaluate the vertical jump performance; however, vertical jump height is slightly overestimated compared with that of the force platform.

A passive air sampler for characterizing the vertical concentration profile of gaseous phase polycyclic aromatic hydrocarbons in near soil surface air

International Nuclear Information System (INIS)

Zhang Yuzhong; Deng Shuxing; Liu Yanan; Shen Guofeng; Li Xiqing; Cao Jun; Wang Xilong; Reid, Brian; Tao Shu

2011-01-01

Air-soil exchange is an important process governing the fate of polycyclic aromatic hydrocarbons (PAHs). A novel passive air sampler was designed and tested for measuring the vertical concentration profile of 4 low molecular weight PAHs in gaseous phase (PAH LMW4 ) in near soil surface air. Air at various heights from 5 to 520 mm above the ground was sampled by polyurethane foam disks held in down-faced cartridges. The samplers were tested at three sites: A: an extremely contaminated site, B: a site near A, and C: a background site on a university campus. Vertical concentration gradients were revealed for PAH LMW4 within a thin layer close to soil surface at the three sites. PAH concentrations either decreased (Site A) or increased (Sites B and C) with height, suggesting either deposition to or evaporation from soils. The sampler is a useful tool for investigating air-soil exchange of gaseous phase semi-volatile organic chemicals. - Research highlights: → Design, field test and calibration of the novel passive air sampler, PAS-V-I. → Vertical concentration gradients of PAH LMW4 within a thin layer close to soil. → Comparison of results between PAS-V-I measurement and fugacity approach. → Potential application of PAS-V-I and further modifications. - A novel passive sampling device was developed and tested for measuring vertical concentration profile of gaseous phase polycyclic aromatic hydrocarbons in near soil surface air.

Evaluating vertical concentration profile of carbon source released from slow-releasing carbon source tablets and in situ biological nitrate denitrification activity

Science.gov (United States)

Yeum, Y.; HAN, K.; Yoon, J.; Lee, J. H.; Song, K.; Kang, J. H.; Park, C. W.; Kwon, S.; Kim, Y.

2017-12-01

Slow-releasing carbon source tablets were manufactured during the design of a small-scale in situ biological denitrification system to reduce high-strength nitrate (> 30 mg N/L) from a point source such as livestock complexes. Two types of slow-releasing tablets, precipitating tablet (PT, apparent density of 2.0 g/mL) and floating tablet (FT), were prepared to achieve a vertically even distribution of carbon source (CS) in a well and an aquifer. Hydroxypropyl methylcellulose (HPMC) was used to control the release rate, and microcrystalline cellulose pH 101 (MCC 101) was added as a binder. The #8 sand was used as a precipitation agent for the PTs, and the floating agents for the FTs were calcium carbonate and citric acid. FTs floated within 30 min. and remained in water because of the buoyance from carbon dioxide, which formed during the acid-base reaction between citric acid and calcium carbonate. The longevities of PTs with 300 mg of HPMC and FTs with 400 mg of HPMC were 25.4 days and 37.3 days, respectively. We assessed vertical CS profile in a continuous flowing physical aquifer model (release test, RT) and its efficiency on biological nitrate denitrification (denitrification test, DT). During the RT, PTs, FTs and a tracer (as 1 mg rhodamine B/L) were initially injected into a well of physical aquifer model (PAM). Concentrations of CS and the tracer were monitored along the streamline in the PAM to evaluate vertical profile of CS. During the DT, the same experiment was performed as RT, except continuous injection of solution containing 30 mg N/L into the PAM to evaluate biological denitrification activity. As a result of RT, temporal profiles of CS were similar at 3 different depths of monitoring wells. These results suggest that simultaneous addition of PT and FT be suitable for achieving a vertically even distribution of the CS in the injection well and an aquifer. In DT, similar profile of CS was detected in the injection well, and nitrate was biologically

Measurement of turbulent flow fields in a agitated vessel with four baffles by laser-doppler velocimetry. Mean velocity fields and flow pattern; Buffle tsuki heiento kakuhan sonai nagare no LDV ni yoru keisoku. Heikin sokudoba to flow pattern

Energy Technology Data Exchange (ETDEWEB)

Suzukawa, K [Ube Industries, Ltd., Tokyo (Japan); hashimoto, T [Yamaguchi University, Yamaguchi (Japan); Osaka, H [Yamaguchi University, Yamaguchi (Japan). Faclty of Engineering

1997-12-25

The three dimensional complex turbulent flow fields induced by a four flat blade paddle impeller in agitated vessel were measured by laser Doppler velocimetry. Mixing vessel used was a closed cylindrical tank of 490 mm diameter with a flat bottom and four vertical buffles, giving water volumes of about 1001. The impellers were at the midnight of the water level in the tank. A height of liquid (water) was equal to the vessel diameter. Three components of mean velocity were measured at three vertical sections {theta}=7.5deg, 45deg and 85deg, in several horizontal planes. Mixing Reynolds number NRe was 1.2 times 10{sup 5}. It can be found from the results that circumferential mean velocity profiles show the symmetrical shape in the upper and lower sides of impeller. Secondary velocity components, such as axial and radial velocities, however, were not in symmetry. For this reason, the ratio of circulation flow volume which enter in upper and lower sides of impeller was roughly 7/3. In both the middle and buffle regions, mean flow velocities (flow patterns) were different, dependent of three vertical planes with different circumferential angle measured from buffle. 10 refs., 8 figs., 1 tab.

Unsteady hydromagnetic flow of dusty fluid and heat transfer over a vertical stretching sheet with thermal radiation

Energy Technology Data Exchange (ETDEWEB)

Isa, Sharena Mohamad; Ali, Anati [Department of Mathematical Sciences, Faculty of Science Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia sharena-ina@yahoo.com, anati@utm.my (Malaysia)

2015-10-22

In this paper, the hydromagnetic flow of dusty fluid over a vertical stretching sheet with thermal radiation is investigated. The governing partial differential equations are reduced to nonlinear ordinary differential equations using similarity transformation. These nonlinear ordinary differential equations are solved numerically using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The behavior of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid is analyzed and discussed for different parameters of interest such as unsteady parameter, fluid-particle interaction parameter, the magnetic parameter, radiation parameter and Prandtl number on the flow.

Visual guidance of forward flight in hummingbirds reveals control based on image features instead of pattern velocity.

Science.gov (United States)

Dakin, Roslyn; Fellows, Tyee K; Altshuler, Douglas L

2016-08-02

Information about self-motion and obstacles in the environment is encoded by optic flow, the movement of images on the eye. Decades of research have revealed that flying insects control speed, altitude, and trajectory by a simple strategy of maintaining or balancing the translational velocity of images on the eyes, known as pattern velocity. It has been proposed that birds may use a similar algorithm but this hypothesis has not been tested directly. We examined the influence of pattern velocity on avian flight by manipulating the motion of patterns on the walls of a tunnel traversed by Anna's hummingbirds. Contrary to prediction, we found that lateral course control is not based on regulating nasal-to-temporal pattern velocity. Instead, birds closely monitored feature height in the vertical axis, and steered away from taller features even in the absence of nasal-to-temporal pattern velocity cues. For vertical course control, we observed that birds adjusted their flight altitude in response to upward motion of the horizontal plane, which simulates vertical descent. Collectively, our results suggest that birds avoid collisions using visual cues in the vertical axis. Specifically, we propose that birds monitor the vertical extent of features in the lateral visual field to assess distances to the side, and vertical pattern velocity to avoid collisions with the ground. These distinct strategies may derive from greater need to avoid collisions in birds, compared with small insects.

The effect of sediment thermal conductivity on vertical groundwater flux estimates

Science.gov (United States)

Sebok, Eva; Müller, Sascha; Engesgaard, Peter; Duque, Carlos

2015-04-01

The interaction between groundwater and surface water is of great importance both from ecological and water management perspective. The exchange fluxes are often estimated based on vertical temperature profiles taken from shallow sediments assuming a homogeneous standard value of sediment thermal conductivity. Here we report on a field investigation in a stream and in a fjord, where vertical profiles of sediment thermal conductivity and temperatures were measured in order to, (i) define the vertical variability in sediment thermal conductivity, (ii) quantify the effect of heterogeneity in sediment thermal conductivity on the estimated vertical groundwater fluxes. The study was carried out at field sites located in Ringkøbing fjord and Holtum stream in Western Denmark. Both locations have soft, sandy sediments with an upper organic layer at the fjord site. First 9 and 12 vertical sediment temperature profiles up to 0.5 m depth below the sediment bed were collected in the fjord and in the stream, respectively. Later sediment cores of 0.05 m diameter were removed at the location of the temperature profiles. Sediment thermal conductivity was measured in the sediment cores at 0.1 m intervals with a Decagon KD2 Pro device. A 1D flow and heat transport model (HydroGeoSphere) was set up and vertical groundwater fluxes were estimated based on the measured vertical sediment temperature profiles by coupling the model with PEST. To determine the effect of heterogeneity in sediment thermal conductivity on estimated vertical groundwater fluxes, the model was run by assigning (i) a homogeneous thermal conductivity for all sediment layers, calculated as the average sediment thermal conductivity of the profile, (ii) measured sediment thermal conductivities to the different model layers. The field survey showed that sediment thermal conductivity over a 0.5 m profile below the sediment bed is not uniform, having the largest variability in the fjord where organic sediments were also

Study on of Seepage Flow Velocity in Sand Layer Profile as Affected by Water Depth and Slope Gradience

Science.gov (United States)

Han, Z.; Chen, X.

2017-12-01

BACKGROUND: The subsurface water flow velocity is of great significance in understanding the hydrodynamic characteristics of soil seepage and the influence of interaction between seepage flow and surface runoff on the soil erosion and sediment transport process. OBJECTIVE: To propose a visualized method and equipment for determining the seepage flow velocity and measuring the actual flow velocity and Darcy velocity as well as the relationship between them.METHOD: A transparent organic glass tank is used as the test soil tank, the white river sand is used as the seepage test material and the fluorescent dye is used as the indicator for tracing water flow, so as to determine the thickness and velocity of water flow in a visualized way. Water is supplied at the same flow rate (0.84 L h-1) to the three parts with an interval of 1m at the bottom of the soil tank and the pore water velocity and the thickness of each water layer are determined under four gradient conditions. The Darcy velocity of each layer is calculated according to the water supply flow and the discharge section area. The effective discharge flow pore is estimated according to the moisture content and porosity and then the relationship between Darcy velocity and the measured velocity is calculated based on the water supply flow and the water layer thickness, and finally the correctness of the calculation results is verified. RESULTS: According to the velocity calculation results, Darcy velocity increases significantly with the increase of gradient; in the sand layer profile, the flow velocity of pore water at different depths increases with the increase of gradient; under the condition of the same gradient, the lower sand layer has the maximum flow velocity of pore water. The air-filled porosity of sand layer determines the proportional relationship between Darcy velocity and pore flow velocity. CONCLUSIONS: The actual flow velocity and Darcy velocity can be measured by a visualized method and the

Profile of capillary bridges between two vertically stacked cylindrical fibers under gravitational effect

Science.gov (United States)

Sun, Xiaohang; Lee, Hoon Joo; Michielsen, Stephen; Wilusz, Eugene

2018-05-01

Although profiles of axisymmetric capillary bridges between two cylindrical fibers have been extensively studied, little research has been reported on capillary bridges under external forces such as the gravitational force. This is because external forces add significant complications to the Laplace-Young equation, making it difficult to predict drop profiles based on analytical approaches. In this paper, simulations of capillary bridges between two vertically stacked cylindrical fibers with gravitational effect taken into consideration are studied. The asymmetrical structure of capillary bridges that are hard to predict based on analytical approaches was studied via a numerical approach based on Surface Evolver (SE). The axial and the circumferential spreading of liquids on two identical fibers in the presence of gravitational effects are predicted to determine when the gravitational effects are significant or can be neglected. The effect of liquid volume, equilibrium contact angle, the distance between two fibers and fiber radii. The simulation results were verified by comparing them with experimental measurements. Based on SE simulations, curves representing the spreading of capillary bridges along the two cylindrical fibers were obtained. The gravitational effect was scaled based on the difference of the spreading on upper and lower fibers.

Development of two-phase flow along a large vertical pipe

International Nuclear Information System (INIS)

Dirk Lucas; Prasser, H.M.

2005-01-01

Full text of publication follows: To qualify CFD codes for two-phase flow simulations, closure laws describing the interaction between the phases are needed. Vertical pipe flow is a suitable object for studying the corresponding phenomena in case of dispersed bubbly flow. Here, the bubbles move under clear boundary conditions, resulting in a shear field of nearly constant structure where the bubbles rise for a comparatively long time. This allows to study the lateral motion of the bubbles in a shear flow as well as bubble coalescence and break-up by comparing gas volume fraction distributions and bubble size distributions at different heights. Very detailed data were obtained at the TOPFLOW facility of the Forschungszentrum Rossendorf using an advanced wire-mesh sensor. This sensor measures the instantaneous conductivity distribution over the pipe cross section. The high frequency of the measurement (2500 frames/s) allows the detection of single bubbles by a special evaluation procedure. Bubble size distributions, gas volume fraction distributions and also gas fraction distributions decomposed according to the bubble size are delivered as result of the evaluation procedure. The use of two sensors allows to measure the profile of the gas velocity. In previous works similar data for pipe of 51.2 mm inner diameter were used for the validation of non-drag bubble forces [1] and the evaluation of the influence of radial profiles on the development of the flow pattern [2]. First investigations on scaling effects were done using data obtained at a pipe with an inner diameter of 194 mm [3]. A constant distance between gas injection and measuring plane of L/D ∼ 40 was used. From a new test series now measurements are available for varying distances between the injection device and the wire-mesh sensor. This allows the evaluation of the development of the flow along the pipe. The data are used for the development and validation of mesoscale models for the forces acting on

Thermal and hydrodynamic characteristics of forced and mixed convection flow through vertical rectangular channels

Directory of Open Access Journals (Sweden)

Hanafi Abdalla S.

2008-01-01

Full Text Available This paper presents experimental and numerical studies for the case of turbulent forced and mixed convection flow of water through narrow vertical rectangular channel. The channel is composed of two parallel plates which are heated at a uniform heat flux, whereas, the other two sides of the channel are thermally insulated. The plates are of 64 mm in width, 800 mm in height, and separated from each other at a narrow gap of 2.7 mm. The Nusselt number distribution along the flow direction normalized by the Nusselt number for the case of turbulent forced convection flow is obtained experimentally with a comparison with the numerical results obtained from a commercial computer code. The quantitative determination of the nor- malized Nusselt number with respect to the dimension-less number Z = (Gr/Re21/8Pr0.5 is presented with a comparison with previous experimental results. Qualitative results are presented for the normalized temperature and velocity profiles in the transverse direction with a comparison between the forced and mixed convection flow for both the cases of upward and downward flow directions. The effect of the axial locations and the parameter Gr/Re on the variation of the normalized temperature profiles in the transverse direction for both the regions of forced and mixed convection and for both of the upward and downward flow directions are obtained. The normalized velocity profiles in the transverse directions are also determined at different inlet velocity and heat fluxes for the previous cases. It is found that the normalized Nusselt number is greater than one in the mixed convection region for both the cases of upward and downward flow and correlated well with the dimension-less parameter Z for both of the forced and mixed convection regions. The temperature profiles increase with increasing the axial location along the flow direction or the parameter Gr/Re for both of the forced and mixed convection regions, but this increase is

Magnetic and velocity fields MHD flow of a stretched vertical ...

African Journals Online (AJOL)

Analytical solutions for heat and mass transfer by laminar flow of Newtonian, viscous, electrically conducting and heat generation/absorbing fluid on a continuously moving vertical permeable surface with buoyancy in the presence of a magnetic field and a first order chemical reaction are reported. The solutions for magnetic ...

Vertical distribution of organochlorine pesticides in humus along Alpine altitudinal profiles in relation to ambiental parameters

Energy Technology Data Exchange (ETDEWEB)

Kirchner, M., E-mail: kirchner@helmholtz-muenchen.d [Helmholtz Zentrum Muenchen, GmbH, Institutes of Ecological Chemistry, Developmental Genetics and Soil Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Faus-Kessler, T.; Jakobi, G.; Levy, W.; Henkelmann, B.; Bernhoeft, S.; Kotalik, J.; Zsolnay, A. [Helmholtz Zentrum Muenchen, GmbH, Institutes of Ecological Chemistry, Developmental Genetics and Soil Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Bassan, R. [Regional Agency for Environmental Prevention and Protection of Veneto (Italy); Belis, C. [Regional Agency for Environmental Protection of Lombardy (Italy); Kraeuchi, N. [Swiss Federal Institute for Forest, Snow and Landscape Research (Switzerland); Moche, W. [Federal Environment Agency Ltd. (Austria); Simoncic, P. [Slovenian Forestry Institute (Slovenia); Uhl, M.; Weiss, P. [Federal Environment Agency Ltd. (Austria); Schramm, K.-W. [Helmholtz Zentrum Muenchen, GmbH, Institutes of Ecological Chemistry, Developmental Genetics and Soil Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

2009-12-15

In forest soils along vertical profiles located in different parts of the Alps, concentrations of persistent organic pollutants (POPs), namely organochlorine pesticides (OCPs) like dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), heptachlor, aldrin, dieldrin and mirex, were measured. Though local characteristics of the sites are influenced by numerous factors like orographic and meteorological parameters, forest stand characteristics and humus parameters, we ascertained a marked vertical increase of concentrations of some organochlorine compounds in the soil. On the basis of climatological values of each site, we found that the contamination increase with altitude can be ascribed to a certain 'cold condensation effect'. In addition, the perennial atmospheric deposition of POPs is controlled by precipitation. Other key parameters explaining the accumulation of POPs are the soil organic carbon stocks, the turnover times, the re-volatilisation and degradation processes, which vary with altitude. - Caused by temperature-dependent processes regarding deposition, re-volatilization and decomposition of POPs, the concentration of organochlorine pesticides varies in the Alpine region with altitude.

Role of the vertical pressure gradient in wave boundary layers

DEFF Research Database (Denmark)

Jensen, Karsten Lindegård; Sumer, B. Mutlu; Vittori, Giovanna

2014-01-01

By direct numerical simulation (DNS) of the flow in an oscillatory boundary layer, it is possible to obtain the pressure field. From the latter, the vertical pressure gradient is determined. Turbulent spots are detected by a criterion involving the vertical pressure gradient. The vertical pressure...... gradient is also treated as any other turbulence quantity like velocity fluctuations and statistical properties of the vertical pressure gradient are calculated from the DNS data. The presence of a vertical pressure gradient in the near bed region has significant implications for sediment transport....

A study of the horizontal and vertical profile of submicrometer particles in relation to a busy road

Science.gov (United States)

Morawska, Lidia; Thomas, Stephen; Gilbert, Dale; Greenaway, Chris; Rijnders, Esther

Epidemiological studies are consistently reporting an association between fine particulate pollution and ill-health. Motor vehicle emissions are considered to be the main source of fine particles in ambient urban air of cities which are not directly influenced by industrial emissions. The aim of this work was to assess the influence of a major arterial road on concentration levels of airborne fine particles in its vicinity. Measurements of over 500 particle size distributions in the particle size range 16-626 nm, were made using two scanning mobility particle sizers (SMPS). A subsequent comparison of the recorded values from differing locations is discussed, with reference made to topographic and climatic influences. Both horizontal and vertical profile measurements of fine particle number size distributions are described; the combination of the two yielding information as to the relative exposures of occupants of buildings in the vicinity of a major arterial route. With the exception of measurements in close proximity to the freeway (about 15 m), the horizontal profile measurements did not provide any evidence of a statistically significant difference in fine particle number concentration with respect to distance at ground level up to a distance of 200 m within the study area. The vertical profile measurements also revealed no significant correlation between particle concentration and height. However, for buildings in the immediate proximity to the arterial road (about 15 m) concentrations around the building envelope are very high, comparable to those in the immediate vicinity of the road, indicating undiluted concentrations drawn directly from the freeway. This finding has a significant implication for management of indoor air quality in the buildings located in the immediate vicinity of major roads.

Velocity profile of water vapor inside a cavity with two axial inlets and two outlets

Science.gov (United States)

Guadarrama-Cetina, José; Ruiz Chavarría, Gerardo

2014-03-01

To study the dynamics of Breath Figure phenomenon, a control of both the rate of flow and temperature of water vapor is required. The experimental setup widely used is a non hermetically closed chamber with cylindrical geometry and axial inlets and outlets. In this work we present measurements in a cylindrical chamber with diameter 10 cm and 1.5 cm height, keeping a constant temperature (10 °C). We are focused in the velocity field when a gradient of the temperatures is produced between the base plate and the vapor. With a flux of water vapor of 250 mil/min at room temperature (21 °C), the Reynolds number measured in one inlet is 755. Otherwise, the temperatures of water vapor varies from 21 to 40 °C. The velocity profile is obtained by hot wire anemometry. We identify the stagnations and the possibly instabilities regions for an empty plate and with a well defined shape obstacle as a fashion sample. Facultad de Ciencias, UNAM.

Cloud vertical profiles derived from CALIPSO and CloudSat and a comparison with MODIS derived clouds

Science.gov (United States)

Kato, S.; Sun-Mack, S.; Miller, W. F.; Rose, F. G.; Minnis, P.; Wielicki, B. A.; Winker, D. M.; Stephens, G. L.; Charlock, T. P.; Collins, W. D.; Loeb, N. G.; Stackhouse, P. W.; Xu, K.

2008-05-01

CALIPSO and CloudSat from the a-train provide detailed information of vertical distribution of clouds and aerosols. The vertical distribution of cloud occurrence is derived from one month of CALIPSO and CloudSat data as a part of the effort of merging CALIPSO, CloudSat and MODIS with CERES data. This newly derived cloud profile is compared with the distribution of cloud top height derived from MODIS on Aqua from cloud algorithms used in the CERES project. The cloud base from MODIS is also estimated using an empirical formula based on the cloud top height and optical thickness, which is used in CERES processes. While MODIS detects mid and low level clouds over the Arctic in April fairly well when they are the topmost cloud layer, it underestimates high- level clouds. In addition, because the CERES-MODIS cloud algorithm is not able to detect multi-layer clouds and the empirical formula significantly underestimates the depth of high clouds, the occurrence of mid and low-level clouds is underestimated. This comparison does not consider sensitivity difference to thin clouds but we will impose an optical thickness threshold to CALIPSO derived clouds for a further comparison. The effect of such differences in the cloud profile to flux computations will also be discussed. In addition, the effect of cloud cover to the top-of-atmosphere flux over the Arctic using CERES SSF and FLASHFLUX products will be discussed.

A relaxed eddy accumulation system for measuring vertical fluxes of nitrous acid

Directory of Open Access Journals (Sweden)

X. Ren

2011-10-01

Full Text Available A relaxed eddy accumulation (REA system combined with a nitrous acid (HONO analyzer was developed to measure atmospheric HONO vertical fluxes. The system consists of three major components: (1 a fast-response sonic anemometer measuring both vertical wind velocity and air temperature, (2 a fast-response controlling unit separating air motions into updraft and downdraft samplers by the sign of vertical wind velocity, and (3 a highly sensitive HONO analyzer based on aqueous long path absorption photometry that measures HONO concentrations in the updrafts and downdrafts. A dynamic velocity threshold (±0.5σ_w, where σ_w is a standard deviation of the vertical wind velocity was used for valve switching determined by the running means and standard deviations of the vertical wind velocity. Using measured temperature as a tracer and the average values from two field deployments, the flux proportionality coefficient, β, was determined to be 0.42 ± 0.02, in good agreement with the theoretical estimation. The REA system was deployed in two ground-based field studies. In the California Research at the Nexus of Air Quality and Climate Change (CalNex study in Bakersfield, California in summer 2010, measured HONO fluxes appeared to be upward during the day and were close to zero at night. The upward HONO flux was highly correlated to the product of NO₂ and solar radiation. During the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX 2009 at Blodgett Forest, California in July 2009, the overall HONO fluxes were small in magnitude and were close to zero. Causes for the different HONO fluxes in the two different environments are briefly discussed.

Extraction of Vertical Profiles of Atmospheric Variables from Gridded Binary, Edition 2 (GRIB2) Model Output Files

Science.gov (United States)

2018-01-18

new_grid will generate a smaller grid interpolated from the fields of the parent grid (http://www.cpc.ncep.noaa.gov/ products/wesley/wgrib2/new_grid.html...the grid or undefined. “latlon” for –new_grid results in a new grid interpolated from the parent (old) grid, where the listed latitude and longitude...by-2 horizontal grid 0.0001° apart, which translates to about a 10-m separation . 2.2 Extract the Vertical Profile Data The second step is to

Measurement of sound velocity profiles in fluids for process monitoring

International Nuclear Information System (INIS)

Wolf, M; Kühnicke, E; Lenz, M; Bock, M

2012-01-01

In ultrasonic measurements, the time of flight to the object interface is often the only information that is analysed. Conventionally it is only possible to determine distances or sound velocities if the other value is known. The current paper deals with a novel method to measure the sound propagation path length and the sound velocity in media with moving scattering particles simultaneously. Since the focal position also depends on sound velocity, it can be used as a second parameter. Via calibration curves it is possible to determine the focal position and sound velocity from the measured time of flight to the focus, which is correlated to the maximum of averaged echo signal amplitude. To move focal position along the acoustic axis, an annular array is used. This allows measuring sound velocity locally resolved without any previous knowledge of the acoustic media and without a reference reflector. In previous publications the functional efficiency of this method was shown for media with constant velocities. In this work the accuracy of these measurements is improved. Furthermore first measurements and simulations are introduced for non-homogeneous media. Therefore an experimental set-up was created to generate a linear temperature gradient, which also causes a gradient of sound velocity.

Radiation and mass transfer effects on an unsteady MHD free convection flow past a heated vertical plate in a porous medium with viscous dissipation

Directory of Open Access Journals (Sweden)

Prasad Ramachandra V.

2007-01-01

Full Text Available An unsteady, two-dimensional, hydromagnetic, laminar free convective boundary-layer flow of an incompressible, Newtonian, electrically-conducting and radiating fluid past an infinite heated vertical porous plate with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer and tabulated results for the skin-friction coefficient, Nusselt number and Sherwood number are presented and discussed. It is observed that, when the radiation parameter increases, the velocity and temperature decrease in the boundary layer, whereas when thermal and solutal Grashof increases the velocity increases.

Hydromagnetic flow and radiative heat transfer of nanofluid past a vertical plate

Directory of Open Access Journals (Sweden)

B. Ganga

2017-11-01

Full Text Available Hydromagnetic flow of an incompressible viscous nanofluid past a vertical plate in the presence of thermal radiation is investigated both analytically and numerically. The radiative heat flux is described by the Rosseland diffusion approximation in the energy equation. The governing non-linear partial differential equations are converted into a set of ordinary differential equations by suitable similarity transformations. The resulting ordinary differential equations are successfully solved analytically with the help of homotopy analysis method and numerically by the fourth order Runge–Kutta method with shooting technique. The effects of various physical parameters are analyzed and discussed in graphical and tabular forms. The effects of some physical parameters such as Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, radiation parameter and magnetic parameter are analyzed on the velocity, temperature and solid volume fraction profiles as well as on the reduced Nusselt number and the local Sherwood number. An excellent agreement is observed between present analytical and numerical results. Keywords: Nanofluid, Hydromagnetic, Homotopy analysis method, Vertical plate and thermal radiation

Dynamics of the standard deviations of three wind velocity components from the data of acoustic sounding

Science.gov (United States)

Krasnenko, N. P.; Kapegesheva, O. F.; Shamanaeva, L. G.

2017-11-01

Spatiotemporal dynamics of the standard deviations of three wind velocity components measured with a mini-sodar in the atmospheric boundary layer is analyzed. During the day on September 16 and at night on September 12 values of the standard deviation changed for the x- and y-components from 0.5 to 4 m/s, and for the z-component from 0.2 to 1.2 m/s. An analysis of the vertical profiles of the standard deviations of three wind velocity components for a 6-day measurement period has shown that the increase of σx and σy with altitude is well described by a power law dependence with exponent changing from 0.22 to 1.3 depending on the time of day, and σz depends linearly on the altitude. The approximation constants have been found and their errors have been estimated. The established physical regularities and the approximation constants allow the spatiotemporal dynamics of the standard deviation of three wind velocity components in the atmospheric boundary layer to be described and can be recommended for application in ABL models.

Comparison of the inversion algorithms applied to the ozone vertical profile retrieval from SCIAMACHY limb measurements

Directory of Open Access Journals (Sweden)

A. Rozanov

2007-09-01

Full Text Available This paper is devoted to an intercomparison of ozone vertical profiles retrieved from the measurements of scattered solar radiation performed by the SCIAMACHY instrument in the limb viewing geometry. Three different inversion algorithms including the prototype of the operational Level 1 to 2 processor to be operated by the European Space Agency are considered. Unlike usual validation studies, this comparison removes the uncertainties arising when comparing measurements made by different instruments probing slightly different air masses and focuses on the uncertainties specific to the modeling-retrieval problem only. The intercomparison was performed for 5 selected orbits of SCIAMACHY showing a good overall agreement of the results in the middle stratosphere, whereas considerable discrepancies were identified in the lower stratosphere and upper troposphere altitude region. Additionally, comparisons with ground-based lidar measurements are shown for selected profiles demonstrating an overall correctness of the retrievals.

Low profile, high load vertical rolling positioning stage

Science.gov (United States)

Shu, Deming; Barraza, Juan

1996-01-01

A stage or support platform assembly for use in a synchrotron accurately positions equipment to be used in the beam line of the synchrotron. The support platform assembly includes an outer housing in which is disposed a lifting mechanism having a lifting platform or stage at its upper extremity on which the equipment is mounted. A worm gear assembly is located in the housing and is adapted to raise and lower a lifting shaft that is fixed to the lifting platform by an anti-binding connection. The lifting platform is moved vertically as the lifting shaft is moved vertically. The anti-binding connection prevents the shaft from rotating with respect to the platform, but does permit slight canting of the shaft with respect to the lifting platform so as to eliminate binding and wear due to possible tolerance mismatches. In order to ensure that the lifting mechanism does not move in a horizontal direction as it is moved vertically, at least three linear roller bearing assemblies are arranged around the outer-periphery of the lifting mechanism. One of the linear roller bearing assemblies can be adjusted so that the roller bearings apply a loading force against the lifting mechanism. Alternatively, a cam mechanism can be used to provide such a loading force.

Liquid velocity in upward and downward air-water flows

International Nuclear Information System (INIS)

Sun Xiaodong; Paranjape, Sidharth; Kim, Seungjin; Ozar, Basar; Ishii, Mamoru

2004-01-01

Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral laser Doppler anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void-weighted area-averaged drift velocity were obtained based on the definitions

Autonomous vertical profiler data management

Digital Repository Service at National Institute of Oceanography (India)

Afzulpurkar, S.; Navelkar, G.S.; Desa, E.S.; Madhan, R.; Dabholkar, N.; Prabhudesai, S.P.; Mascarenhas, A.A.M.Q.

the data management. It is expected that there would be multiple profilers operating at various locations, such as coastal seas, dams and other water bodies. Data would be relayed for archival, processing and be made available to the communities who...

Effect of moment of inertia to H type vertical axis wind turbine aerodynamic performance

International Nuclear Information System (INIS)

Yang, C X; Li, S T

2013-01-01

The main aerodynamic performances (out power out power coefficient torque torque coefficient and so on) of H type Vertical Axis wind Turbine (H-VAWT) which is rotating machinery will be impacted by moment of inertia. This article will use NACA0018 airfoil profile to analyze that moment of inertia through impact performance of H type VAWT by utilizing program of Matlab and theory of Double-Multiple Streamtube. The results showed that the max out power coefficient was barely impacted when moment of inertia is changed in a small area,but the lesser moment of inertia's VAWT needs a stronger wind velocity to obtain the max out power. The lesser moment of inertia's VAWT has a big out power coefficient, torque coefficient and out power before it gets to the point of max out power coefficient. Out power coefficient, torque and torque coefficient will obviously change with wind velocity increased for VAWT of the lesser moment of inertia

Turbulent flow velocity distribution at rough walls

International Nuclear Information System (INIS)

Baumann, W.

1978-08-01

Following extensive measurements of the velocity profile in a plate channel with artificial roughness geometries specific investigations were carried out to verify the results obtained. The wall geometry used was formed by high transverse square ribs having a large pitch. The measuring position relative to the ribs was varied as a parameter thus providing a statement on the local influence of roughness ribs on the values measured. As a fundamental result it was found that the gradient of the logarithmic rough wall velocity profiles, which differs widely from the value 2.5, depends but slightly on the measuring position relative to the ribs. The gradients of the smooth wall velocity profiles deviate from 2.5 near the ribs, only. This fact can be explained by the smooth wall shear stress varying with the pitch of the ribs. (orig.) 891 GL [de

Effects of Isometric Scaling on Vertical Jumping Performance

Science.gov (United States)

Bobbert, Maarten F.

2013-01-01

Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli’s law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations. PMID:23936494

Effects of isometric scaling on vertical jumping performance.

Directory of Open Access Journals (Sweden)

Maarten F Bobbert

Full Text Available Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli's law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations.

HEAT AND MASS TRANSFER EFFECTS ON FLOW PAST PARABOLIC STARTING MOTION OF ISOTHERMAL VERTICAL PLATE IN THE PRESENCE OF FIRST ORDER CHEMICAL REACTION

Directory of Open Access Journals (Sweden)

R. Muthucumaraswamy

2013-06-01

Full Text Available An exact solution of unsteady flow past a parabolic starting motion of the infinite isothermal vertical plate with uniform mass diffusion, in the presence of a homogeneous chemical reaction of the first order, has been studied. The plate temperature and the concentration level near the plate are raised uniformly. The dimensionless governing equations are solved using the Laplace transform technique. The effect of velocity profiles are studied for different physical parameters, such as chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, and time. It is observed that velocity increases with increasing values of thermal Grashof number or mass Grashof number. The trend is reversed with respect to the chemical reaction parameter.

Modeling tides and vertical tidal mixing: A reality check

International Nuclear Information System (INIS)

Robertson, Robin

2010-01-01

Recently, there has been a great interest in the tidal contribution to vertical mixing in the ocean. In models, vertical mixing is estimated using parameterization of the sub-grid scale processes. Estimates of the vertical mixing varied widely depending on which vertical mixing parameterization was used. This study investigated the performance of ten different vertical mixing parameterizations in a terrain-following ocean model when simulating internal tides. The vertical mixing parameterization was found to have minor effects on the velocity fields at the tidal frequencies, but large effects on the estimates of vertical diffusivity of temperature. Although there was no definitive best performer for the vertical mixing parameterization, several parameterizations were eliminated based on comparison of the vertical diffusivity estimates with observations. The best performers were the new generic coefficients for the generic length scale schemes and Mellor-Yamada's 2.5 level closure scheme.

Premotor neurons encode torsional eye velocity during smooth-pursuit eye movements

Science.gov (United States)

Angelaki, Dora E.; Dickman, J. David

2003-01-01

Responses to horizontal and vertical ocular pursuit and head and body rotation in multiple planes were recorded in eye movement-sensitive neurons in the rostral vestibular nuclei (VN) of two rhesus monkeys. When tested during pursuit through primary eye position, the majority of the cells preferred either horizontal or vertical target motion. During pursuit of targets that moved horizontally at different vertical eccentricities or vertically at different horizontal eccentricities, eye angular velocity has been shown to include a torsional component the amplitude of which is proportional to half the gaze angle ("half-angle rule" of Listing's law). Approximately half of the neurons, the majority of which were characterized as "vertical" during pursuit through primary position, exhibited significant changes in their response gain and/or phase as a function of gaze eccentricity during pursuit, as if they were also sensitive to torsional eye velocity. Multiple linear regression analysis revealed a significant contribution of torsional eye movement sensitivity to the responsiveness of the cells. These findings suggest that many VN neurons encode three-dimensional angular velocity, rather than the two-dimensional derivative of eye position, during smooth-pursuit eye movements. Although no clear clustering of pursuit preferred-direction vectors along the semicircular canal axes was observed, the sensitivity of VN neurons to torsional eye movements might reflect a preservation of similar premotor coding of visual and vestibular-driven slow eye movements for both lateral-eyed and foveate species.

Derivation of gravity wave intrinsic parameters and vertical wavelength using a single scanning OH(3-1) airglow spectrometer

Science.gov (United States)

Wüst, Sabine; Offenwanger, Thomas; Schmidt, Carsten; Bittner, Michael; Jacobi, Christoph; Stober, Gunter; Yee, Jeng-Hwa; Mlynczak, Martin G.; Russell, James M., III

2018-05-01

For the first time, we present an approach to derive zonal, meridional, and vertical wavelengths as well as periods of gravity waves based on only one OH* spectrometer, addressing one vibrational-rotational transition. Knowledge of these parameters is a precondition for the calculation of further information, such as the wave group velocity vector.OH(3-1) spectrometer measurements allow the analysis of gravity wave ground-based periods but spatial information cannot necessarily be deduced. We use a scanning spectrometer and harmonic analysis to derive horizontal wavelengths at the mesopause altitude above Oberpfaffenhofen (48.09° N, 11.28° E), Germany for 22 nights in 2015. Based on the approximation of the dispersion relation for gravity waves of low and medium frequencies and additional horizontal wind information, we calculate vertical wavelengths. The mesopause wind measurements nearest to Oberpfaffenhofen are conducted at Collm (51.30° N, 13.02° E), Germany, ca. 380 km northeast of Oberpfaffenhofen, by a meteor radar.In order to compare our results, vertical temperature profiles of TIMED-SABER (thermosphere ionosphere mesosphere energetics dynamics, sounding of the atmosphere using broadband emission radiometry) overpasses are analysed with respect to the dominating vertical wavelength.

Velocity Dispersions Across Bulge Types

International Nuclear Information System (INIS)

Fabricius, Maximilian; Bender, Ralf; Hopp, Ulrich; Saglia, Roberto; Drory, Niv; Fisher, David

2010-01-01

We present first results from a long-slit spectroscopic survey of bulge kinematics in local spiral galaxies. Our optical spectra were obtained at the Hobby-Eberly Telescope with the LRS spectrograph and have a velocity resolution of 45 km/s (σ*), which allows us to resolve the velocity dispersions in the bulge regions of most objects in our sample. We find that the velocity dispersion profiles in morphological classical bulge galaxies are always centrally peaked while the velocity dispersion of morphologically disk-like bulges stays relatively flat towards the center--once strongly barred galaxies are discarded.

Air-driven viscous film flow coating the interior of a vertical tube

Science.gov (United States)

Ogrosky, H. Reed; Camassa, Roberto; Olander, Jeffrey

2017-11-01

We discuss a model for the flow of a viscous liquid film coating the interior of a vertical tube when the film is driven upwards against gravity by airflow through the center of the tube. The model consists of two components: (i) a nonlinear model, exploiting the slowly-varying liquid-air interface, for the interfacial stresses created by the airflow, and (ii) a long-wave asymptotic model for the air-liquid interface. The stability of small interfacial disturbances is studied analytically, and it is shown that the modeled free surface stresses contribute to both an increased upwards disturbance velocity and a more rapid instability growth than those of a previously developed model. Numerical solutions to the long-wave model exhibit saturated waves whose profiles and velocities show improvement, with respect to the previous model, in matching experiments. The model results are then compared with additional experiments for a slightly modified version of the problem. We gratefully acknowledge funding from NSF DMS-0509423, DMS-0908423, DMS-1009750, DMS-1517879, RTG DMS-0943851, CMG ARC-1025523 and NIEHS 534197-3411.