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Profile Measurements (profile + measurement)

Distribution by Scientific Domains

Physics and Astronomy	33%

Selected Abstracts

QUANTIFICATION AND DISCRIMINATION OF LITHIC USE-WEAR: SURFACE PROFILE MEASUREMENTS AND LENGTH-SCALE FRACTAL ANALYSIS*

ARCHAEOMETRY, Issue 3 2009
W. J. STEMP
This experimental programme employs length-scale analysis of measured profiles to quantitatively discriminate the surface textures of stone flakes manufactured from East Anglian chalk flint used on four contact materials (shell, wood, dry hide and soaked antler). It presents a method for evaluating texture characterization parameters based on their ability to discriminate wear types, and to determine a level of confidence to the discrimination, using the F -test. The results of this experimental work demonstrate that relative lengths, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials. [source]

Fast Reciprocating Probe Assembly for the KSTAR

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2006
J. G. Bak
Abstract A fast reciprocating probe assembly (FRPA) that can scan a distance of up to 32.5 cm with a maximum speed of 1.7 m/s was fabricated to obtain the spatial profile of basic plasma parameters in the edge region of the KSTAR plasma during a plasma discharge of 20 s. The probe driving mechanism consists of two parts; first a slow movement driven by a servo motor system and then a fast reciprocating movement actuated by a pneumatic system. A performance test of the drive system, which is remotely controlled by a PC, was carried out. The prototype of the probe head for the KSTAR FRPA was fabricated as a modular type for easy replacement. It was installed in the fast injection probe assembly (FIPA) in the Hanbit magnetic mirror device, and a radial plasma parameter profile measurement was carried out. The performance test results of the drive system and the profile measurements using the probe head are presented. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Mechanism of Local Fluidization in Converging Packed Beds

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2003
Baoquan Zhang
Abstract The velocity profile on the bed surface of two-dimensional linear-converging beds with 15° and 30° wall angles was measured at different superficial velocities using hot-wire anemometry. The results of the velocity measurements indicate that local fluidization in the corners is caused by the geometry-induced maldistribution of fluid flow, and it occurs when the velocity in the corners exceeds the minimum fluidization velocity of particles. The results of pressure measurements within the bed show the same trend as the velocity profile, providing a qualitative verification of the velocity profile measurement. It is shown that the variation of measured pressure drop over the bed with velocity does not agree with the Ergun equation at high superficial velocities due to the severe maldistribution of fluid flow. Le profil de vitesse à la surface du lit de lits linéaires-convergents bidimensionnels avec des angles de paroi de 15 et 30∞ a été mesuré à différentes vitesses superficielles par anémométrie à fil chaud. Les résultats des mesures de vitesse indiquent que la fluidisation locale dans les coins provient de la mauvaise distribution causée par la géométrie de l'écoulement du fluide, et qu'elle survient lorsque la vitesse dans les coins excède la vitesse de fluidisation minimale des particules. Les résultats des mesures de pression dans le lit montrent la même tendance que le profil de vitesse, permettant ainsi une vérification qualitative de la mesure des profils de vitesse. On montre que la variation de la perte de charge mesurée dans le lit en fonction de la vitesse ne concorde pas avec l'équation d'Ergun à des vitesses superficielles élevées en raison de la très mauvaise distribution de l'écoulement du fluide. [source]

Fast Reciprocating Probe Assembly for the KSTAR

Modelling night-time ecosystem respiration by a constrained source optimization method

GLOBAL CHANGE BIOLOGY, Issue 2 2002
Chun-Ta Lai
Abstract One of the main challenges to quantifying ecosystem carbon budgets is properly quantifying the magnitude of night-time ecosystem respiration. Inverse Lagrangian dispersion analysis provides a promising approach to addressing such a problem when measured mean CO2 concentration profiles and nocturnal velocity statistics are available. An inverse method, termed ,Constrained Source Optimization' or CSO, which couples a localized near-field theory (LNF) of turbulent dispersion to respiratory sources, is developed to estimate seasonal and annual components of ecosystem respiration. A key advantage to the proposed method is that the effects of variable leaf area density on flow statistics are explicitly resolved via higher-order closure principles. In CSO, the source distribution was computed after optimizing key physiological parameters to recover the measured mean concentration profile in a least-square fashion. The proposed method was field-tested using 1 year of 30-min mean CO2 concentration and CO2 flux measurements collected within a 17-year-old (in 1999) even-aged loblolly pine (Pinus taeda L.) stand in central North Carolina. Eddy-covariance flux measurements conditioned on large friction velocity, leaf-level porometry and forest-floor respiration chamber measurements were used to assess the performance of the CSO model. The CSO approach produced reasonable estimates of ecosystem respiration, which permits estimation of ecosystem gross primary production when combined with daytime net ecosystem exchange (NEE) measurements. We employed the CSO approach in modelling annual respiration of above-ground plant components (c. 214 g C m,2 year,1) and forest floor (c. 989 g C m,2 year,1) for estimating gross primary production (c. 1800 g C m,2 year,1) with a NEE of c. 605 g C m,2 year,1 for this pine forest ecosystem. We conclude that the CSO approach can utilise routine CO2 concentration profile measurements to corroborate forest carbon balance estimates from eddy-covariance NEE and chamber-based component flux measurements. [source]

Vadose Zone Flow Model Uncertainty as Conditioned on Geophysical Data

GROUND WATER, Issue 2 2003
Andrew Binley
An approach to estimating the uncertainty in model descriptions based on a landscape space to model space mapping concept is described. The approach is illustrated by an application making use of plot scale geophysical estimates of changes in water content profiles to condition a model of recharge to the Sherwood Sandstone Aquifer in the United Kingdom. It is demonstrated that the mapping is highly uncertain and that many different parameter sets give acceptable simulations of the observations. Multiple profile measurements over time offer only limited additional constraints on the mapping. The resulting mapping weights may be used to evaluate uncertainty in the predictions of vadose zone flow dynamics for the site. [source]

Non-neurogenic urinary retention (Fowler's syndrome) in two sisters

NEUROUROLOGY AND URODYNAMICS, Issue 7 2006
Simon Podnar
Abstract Aims To report for the first time occurrence of obstructed voiding due to excessive activity of the urethral sphincter (US) muscle in two sisters with polycystic ovaries (Fowler's syndrome). Methods In both patients precise micturition history was obtained. In addition, clinical neurological and gynecological examinations, cystometry, urethral pressure profile measurements, gynecological ultrasound, measurement of gonadotropic hormone levels, and concentric needle electromyography (EMG) of the US muscle were performed. Results Both sisters reported symptoms of severely obstructed voiding. Clinical examination, and filling cystometries were normal. Urethral pressures were increased (99,134 cm water). The first sister was not able to void, and the urinary flow was slow and intermittent in the second on voiding studies. Profuse complex repetitive discharges and decelerating burst activity were found on concentric needle EMG of the US in both of them. Both sisters had increased LH/FSH ratio (2.96 and 2.64), and ultrasonographic abnormalities compatible with polycystic ovaries. Conclusions Diagnosis of Fowler's syndrome was made in both sisters. Due to very low incidence rate of this syndrome (0.2/100.000 per year), we think that it is highly unlikely to find it in two sisters just by chance. We suggest that the probable explanation is a genetic predisposition to polycystic ovaries, with which this condition has been shown to be associated. Neurourol. Urodynam. 25:739,741, 2006. © 2006 Wiley-Liss, Inc. [source]

Positron experiments at the new positron beam facility NEPOMUC at FRM II

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007
C. Hugenschmidt
Abstract The in-pile positron source NEPOMUC of the Munich research reactor FRM II delivers a low-energy positron beam of highest intensity. Different source potentials can be applied in order to vary the primary kinetic energy of the positrons in the range between 15 eV and 1 keV. The maximum yield of slow positrons is up to 4 × 107 and 5 × 108 moderated positrons per second, respectively. New instruments for beam diagnostics have been implemented for the determination of the positron intensity and for positron beam profile measurements. The long-term stability and the degradation of the platinum moderator as well as the recovery procedure were investigated. In the present arrangement of NEPOMUC's instrumentation the monoenergetic positron beam is magnetically guided to different experiments: a coincident Doppler broadening spectrometer (CDBS) and an analysis chamber for positron induced Auger electron spectroscopy (PAES). In addition, an apparatus for the production of the negatively charged positronium ion was connected to the beam line in order to investigate this bound leptonic system in collaboration with the Max-Planck Institute for nuclear physics. An overview of the beam performance, the current status of the positron beam facility and the experiments is presented. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effects of shear sheltering in a stable atmospheric boundary layer with strong shear

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 596 2004
Ann-Sofi Smedman
Abstract Data from two marine field experiments in the Baltic Sea with stable stratification have been analysed. The purpose was to test the concept of the ,detached' or ,top-down' eddies and the ,shear-sheltering' mechanism in the presence of a low-level wind speed maximum in the atmosphere. Data used include turbulence and profile measurements on two 30 m towers and concurrent wind profiles throughout the boundary layer obtained from pilot-balloon soundings. Measurements show that large eddies are being suppressed when there is a low-level wind speed maximum present somewhere in the layer 40,300 m above the water surface and when the stratification is slightly stable. The effect is seen both in normalized standard deviations of the velocity components and in corresponding component spectra. In previous work it was argued that the relatively large eddies, which dominate the low wave number spectra in measurements in the surface layer, are detached or top-down eddies generated higher up in the boundary layer, that interact with the surface layer. The low-level wind maximum introduces a distinct layer with strong vorticity which, according to the shear-sheltering hypothesis, prevents these eddies from penetrating downwards. In the limit of the wind maximum occurring at a very low height (less than about 100 m), usual turbulence statistics characteristic of the ,canonical' boundary layer are found. Combining all the statistics, it is demonstrated that the wavelength of maximum spectral energy is locally related to a turbulence length-scale, which shows that for values of the Richardson number of unity or less the effect of the local wind gradient is greater than that of static stability. The reduction of length-scale with the strength of a low-level wind maximum, explains the observed reduction (by a factor of two) of the turbulent flux of sensible heat at the surface. This result indicates that the shear-sheltering mechanism is likely to play an important role in the turbulent exchange process at the surface in sea areas where low-level wind maxima are a frequently occurring phenomenon, such as the Baltic and other large water bodies surrounded by landmasses. Copyright © 2004 Royal Meteorological Society [source]