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Sample records for volumetric flow rate

  1. Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation.

    Science.gov (United States)

    Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang

    2017-12-01

    Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

  2. Accurate measurements of experimental parameters in supercritical fluid chromatography. I. Extent of variations of the mass and volumetric flow rates.

    Science.gov (United States)

    Tarafder, Abhijit; Guiochon, Georges

    2013-04-12

    Previous reports have highlighted the influence of the properties of the mobile phase flow rate on the column performance achieved in supercritical fluid chromatography (SFC). In SFC both the mass and the volumetric flow rates have unique influences on the chromatographic performance and the determination of their exact values is critical. It is well understood that the mass flow rate stays constant along an SFC system whereas the volumetric flow rate may vary considerably, but the extent of these variations and the role of the individual operating parameters in influencing these variations have not been clearly reported yet. The factors that control the mass and the volumetric flow rates in an SFC system are discussed and the possible extent of variations of these flow rates under different operating pressures and temperatures are demonstrate quantitatively. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. In vivo label-free measurement of lymph flow velocity and volumetric flow rates using Doppler optical coherence tomography.

    Science.gov (United States)

    Blatter, Cedric; Meijer, Eelco F J; Nam, Ahhyun S; Jones, Dennis; Bouma, Brett E; Padera, Timothy P; Vakoc, Benjamin J

    2016-07-05

    Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates. We overcome the challenge of very low scattering by employing a Doppler algorithm that operates on low signal-to-noise measurements. We show that this technique can measure lymph velocity at sufficiently high temporal resolution to resolve the dynamic pulsatile flow in collecting lymphatic vessels.

  4. Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

    Directory of Open Access Journals (Sweden)

    Bieliński Henryk

    2016-09-01

    Full Text Available The current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.

  5. Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

    Science.gov (United States)

    Bieliński, Henryk

    2016-09-01

    The current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.

  6. Driving Fast Flows with Volumetric Current Drive

    Science.gov (United States)

    Milhone, Jason; Endrizzi, D.; Flanagan, K.; Nornberg, M. D.; Peterson, E. E.; Forest, C. B.

    2017-10-01

    Volumetric current drive has been shown to be an efficient method for driving fast flows with high Rm for studying the onset of flow-driven plasma instabilities. High performance plasmas are produced with 20 kW of electron cyclotron heating (ECH) and thermally emissive lanthanum hexaboride cathodes. Plasma flow is achieved by injecting current through the plasma across an externally applied weak magnetic field setting up a J × B body force on the plasma volume. Two scenarios for volumetric current drive have been demonstrated. The first injects current across a weak uniform axial magnetic field driving a Keplerian-like flow for magneto-rotational instability (MRI) studies. The second injects current across a weak quadrupole magnetic field for driving a von Karman-like flow for dynamo studies. First results measuring velocity and ion temperature profiles measured by a Fabry-Perot interferometer are shown. Detailed mach probe flow measurements show stronger flow shear in volumetric current drive compared to previous edge-driven plasma flow experiments. Worked funded by NSF and DOE.

  7. Volumetric lattice Boltzmann simulation for blood flow in aorta arteries

    Science.gov (United States)

    Deep, Debanjan; Yu, Huidan (Whitney); Teague, Shawn

    2012-11-01

    Complicated moving boundaries pose a major challenge in computational fluid dynamics for complex flows, especially in the biomechanics of both blood flow in the cardiovascular system and air flow in the respiratory system where the compliant nature of the vessels can have significant effects on the flow rate and wall shear stress. We develop a computation approach to treat arbitrarily moving boundaries using a volumetric representation of lattice Boltzmann method, which distributes fluid particles inside lattice cells. A volumetric bounce-back procedure is applied in the streaming step while momentum exchange between the fluid and moving solid boundary are accounted for in the collision sub-step. Additional boundary-induced migration is introduced to conserve fluid mass as the boundary moves across fluid cells. The volumetric LBM (VLBM) is used to simulate blood flow in both normal and dilated aorta arteries. We first compare flow structure and pressure distribution in steady state with results from Navier-Stokes based solver and good agreements are achieved. Then we focus on wall stress within the aorta for different heart pumping condition and present quantitative measurement of wall shear and normal stress.

  8. Designing remote web-based mechanical-volumetric flow meter ...

    African Journals Online (AJOL)

    Today, in water and wastewater industry a lot of mechanical-volumetric flow meters are used for the navigation of the produced water and the data of these flow meters, due to use in a wide geographical range, is done physically and by in person presence. All this makes reading the data costly and, in some cases, due to ...

  9. Volumetric velocity measurements on flows through heart valves

    Science.gov (United States)

    Troolin, Daniel; Amatya, Devesh; Longmire, Ellen

    2009-11-01

    Volumetric velocity fields inside two types of artificial heart valves were obtained experimentally through the use of volumetric 3-component velocimetry (V3V). Index matching was used to mitigate the effects of optical distortions due to interfaces between the fluid and curved walls. The steady flow downstream of a mechanical valve was measured and the results matched well with previously obtained 2D PIV results, such as those of Shipkowitz et al. (2002). Measurements upstream and downstream of a deformable silicone valve in a pulsatile flow were obtained and reveal significant three-dimensional features of the flow. Plots and movies will be shown, and a detailed discussion of the flow and various experimental considerations will be included. Reference: Shipkowitz, T, Ambrus J, Kurk J, Wickramasinghe K (2002) Evaluation technique for bileaflet mechanical valves. J. Heart Valve Disease. 11(2) pp. 275-282.

  10. Volumetric flow around a swimming lamprey

    Science.gov (United States)

    Lehn, Andrea M.; Colin, Sean P.; Costello, John H.; Leftwich, Megan C.; Tytell, Eric D.

    2015-11-01

    A primary experimental technique for studying fluid-structure interactions around swimming fish has been planar dimensional particle image velocimetry (PIV). Typically, two components of the velocity vector are measured in a plane, in the case of swimming studies, directly behind the animal. While useful, this approach provides little to no insight about fluid structure interactions above and below the fish. For fish with a small height relative to body length, such as the long and approximately cylindrical lamprey, 3D information is essential to characterize how these fish interact with their fluid environment. This study presents 3D flow structures along the body and in the wake of larval lamprey, P etromyzon m arinus , which are 10-15 cm long. Lamprey swim through a 1000 cm3 field of view in a standard 10 gallon tank illuminated by a green laser. Data are collected using the three component velocimeter V3V system by TSI, Inc. and processed using Insight 4G software. This study expands on previous works that show two pairs of vortices each tail beat in the mid-plane of the lamprey wake. NSF DMS 1062052.

  11. Volumetric Velocity Measurements of Pulsating Flow through a Model Aneurysm

    Science.gov (United States)

    Troolin, Daniel; Amatya, Devesh; Longmire, Ellen

    2010-11-01

    Volumetric 3-component velocimetry (V3V) was used to examine the flow structure inside of a scaled-up transparent urethane model of a saccular aneurysm. The model was fabricated to match the geometry of an in vivo case. Index matching was used to minimize optical distortions caused by the curved walls of the model. The model and a surrounding visualization box were integrated into a custom-built pulse duplicator system with in-line flow meter and pressure transducers. The pulsing frequency and amplitude were controlled independently to generate two flow conditions each having a non-dimensional peak Reynolds (Re) and Womersley (Wo) Number: Re = 250, Wo = 10.4 and Re = 125, Wo = 7.4. Phase-locked and instantaneous measurements of the pulsatile flow upstream, downstream, and within the aneurysm reveal significant three-dimensional features including zones of separation, recirculation, impingement, and relative inactivity. Plots and movies will be shown, and a detailed discussion of the flow and various experimental considerations will be included.

  12. GPU accelerated OCT processing at megahertz axial scan rate and high resolution video rate volumetric rendering

    Science.gov (United States)

    Jian, Yifan; Wong, Kevin; Sarunic, Marinko V.

    2013-03-01

    In this report, we describe how to highly optimize a CUDA based platform to perform real time optical coherence tomography data processing and 3D volumetric rendering using commercially-available cost-effective graphic processing units (GPUs). The maximum complete attainable axial scan processing rate (including memory transfer and rendering frame) was 2.2 megahertz for 16 bits pixel depth and 2048 pixels/A-scan, the maximum 3D volumetric rendering speed is 23 volumes/second (size:1024×256×200). To the best of our knowledge, this is the fastest processing rate reported to date with single-chip GPU and the first implementation of real time video rate volumetric OCT processing and rendering that is capable of matching the ultrahigh-speed OCT acquisition rates.

  13. Environmental Consequences of Volumetric Traffic Flow in Calabar ...

    African Journals Online (AJOL)

    Findings revealed that, Air pollutant such as carbon dioxide (C02) nitrogen oxides (N0) Sulphur dioxide (SO2), Carbon monoxide (C0) and particulate concentrations were above threshold level. With this result of analyses, it shows that there is a positive relationship between air pollutants concentration and volumetric traffic ...

  14. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    , current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI...

  15. Mathematical Modeling of Electrolyte Flow Dynamic Patterns and Volumetric Flow Penetrations in the Flow Channel over Porous Electrode Layered System in Vanadium Flow Battery with Serpentine Flow Field Design

    CERN Document Server

    Ke, Xinyou; Alexander, J Iwan D; Savinell, Robert F

    2016-01-01

    In this work, a two-dimensional mathematical model is developed to study the flow patterns and volumetric flow penetrations in the flow channel over the porous electrode layered system in vanadium flow battery with serpentine flow field design. The flow distributions at the interface between the flow channel and porous electrode are examined. It is found that the non-linear pressure distributions can distinguish the interface flow distributions under the ideal plug flow and ideal parabolic flow inlet boundary conditions. However, the volumetric flow penetration within the porous electrode beneath the flow channel through the integration of interface flow velocity reveals that this value is identical under both ideal plug flow and ideal parabolic flow inlet boundary conditions. The volumetric flow penetrations under the advection effects of flow channel and landing/rib are estimated. The maximum current density achieved in the flow battery can be predicted based on the 100% amount of electrolyte flow reactant ...

  16. Power Outputs and Volumetric Eruption Rates for Ionian Volcanoes from Galileo-NIMS Data

    Science.gov (United States)

    Davies, A. G.

    2001-01-01

    Volumetric eruption rates for a number of Io volcanoes are calculated as a function of volcanic thermal output. Thermal output is determined using 2-temperature fits to NIMS data. Typical eruption rates are larger than terrestrial eruptions of similar style. Additional information is contained in the original extended abstract.

  17. Peak expiratory flow at increased barometric pressure: comparison of peak flow meters and volumetric spirometer.

    Science.gov (United States)

    Thomas, P S; Ng, C; Bennett, M

    2000-01-01

    Increasing numbers of patients are receiving hyperbaric oxygen therapy as an intensive care treatment, some of whom have pre-existing airway obstruction. Spirometers are the ideal instruments for measuring airway obstruction, but peak flow meters are useful and versatile devices. The behaviour of both types of device was therefore studied in a hyperbaric unit under conditions of increased pressure. It is important to have a non-electrical indicator of airway obstruction, to minimize the fire risk in the hyperoxic environment. The hypothesis was tested that, assuming that dynamic resistance is unchanged, both the Wright's standard and mini-peak flow meters would over-read peak expiratory flow (PEF) under increased pressure when compared with a volumetric spirometer, as the latter is unaffected by air density. It was postulated that a correction factor could be derived so that PEF meters could be used in this setting. Seven normal subjects performed volume-dependent spirometry to derive PEF, and manoeuvres using both standard and mini PEF meters at sea level, under hyperbaric conditions at 303, 253 and 152 kPa (3, 2.5 and 1.5 atmospheres respectively; 1 atmosphere absolute=101.08 kPa), and again at sea level. There was a progressive and significant decline in PEF with increasing pressure as measured by the spirometer (69.46+/-0.8% baseline at 303 kPa compared with 101 kPa), while the PEF meters showed a progressive increase in their readings (an increase of 7.86+/-1.69% at 303 kPa with the mini PEF meter). Using these data points, a correction factor was derived which allows appropriate values to be calculated from the Wright's meter readings under these conditions.

  18. Stereo vision for fully automatic volumetric flow measurement in urban drainage structures

    Science.gov (United States)

    Sirazitdinova, Ekaterina; Pesic, Igor; Schwehn, Patrick; Song, Hyuk; Satzger, Matthias; Weingärtner, Dorothea; Sattler, Marcus; Deserno, Thomas M.

    2017-06-01

    Overflows in urban drainage structures, or sewers, must be prevented on time to avoid their undesirable consequences. An effective monitoring system able to measure volumetric flow in sewers is needed. Existing stateof-the-art technologies are not robust against harsh sewer conditions and, therefore, cause high maintenance expenses. Having the goal of fully automatic, robust and non-contact volumetric flow measurement in sewers, we came up with an original and innovative idea of a vision-based system for volumetric flow monitoring. On the contrast to existing video-based monitoring systems, we introduce a second camera to the setup and exploit stereo-vision aiming of automatic calibration to the real world. Depth of the flow is estimated as the difference between distances from the camera to the water surface and from the camera to the canal's bottom. Camerato-water distance is recovered automatically using large-scale stereo matching, while the distance to the canal's bottom is measured once upon installation. Surface velocity is calculated using cross-correlation template matching. Individual natural particles in the flow are detected and tracked throughout the sequence of images recorded over a fixed time interval. Having the water level and the surface velocity estimated and knowing the geometry of the canal we calculate the discharge. The preliminary evaluation has shown that the average error of depth computation was 3 cm, while the average error of surface velocity resulted in 5 cm/s. Due to the experimental design, these errors are rough estimates: at each acquisition session the reference depth value was measured only once, although the variation in volumetric flow and the gradual transitions between the automatically detected values indicated that the actual depth level has varied. We will address this issue in the next experimental session.

  19. Environmental Consequences of Volumetric Traffic Flow in Calabar ...

    African Journals Online (AJOL)

    User

    2011-05-20

    May 20, 2011 ... Lagos, over 62 percent of motor accident was recorded in Lagos in 2001. ... the situation is not different as the abolition of motor cyclist transport in the ..... Hydrogen sulphide. 0.005 mg3 per day. Chloride. 0.03 mg3 per day. Source: FEPA (1991). Table 4: Estimated yearly accident rate in Calabar metropo lis.

  20. An Investigation of the High Rate Volumetric Properties of Snow.

    Science.gov (United States)

    1981-11-01

    v: IV$ LIEA < VISCOELAS TIC LIEA MA TERIA L TIME t () CREEP TEST EI>L LINEA R V/SC QELASTIcI MA 7CR/A L U (b) DEFORMATION - RATE TEST i iqur,. 1...GRAIN and NECK GEOMETRY 7 2 I~~~~~~r b.IELZE RI GOER I ~ ~ ~ 1 z~g~ P9 . A~peetto fgan~dbodgoer o ekgot tuc ~ ~ ~ ~ReIO ofIo efrain ITT I 34 during the...Spontaneous Fracture Invitation in Mountain Snowpacks. J. of Glaciology, Vol. 19, No. 81. Salm, B. (1974) A Constitutive Equation for Creeping Snow

  1. Mathematical Modeling of Electrolyte Flow Dynamic Patterns and Volumetric Flow Penetrations in the Flow Channel over Porous Electrode Layered System in Vanadium Flow Battery with Serpentine Flow Field Design

    OpenAIRE

    Ke, Xinyou; Prahl, Joseph M.; Alexander, J. Iwan D.; Savinell, Robert F.

    2016-01-01

    In this work, a two-dimensional mathematical model is developed to study the flow patterns and volumetric flow penetrations in the flow channel over the porous electrode layered system in vanadium flow battery with serpentine flow field design. The flow distributions at the interface between the flow channel and porous electrode are examined. It is found that the non-linear pressure distributions can distinguish the interface flow distributions under the ideal plug flow and ideal parabolic fl...

  2. Digital image processing based mass flow rate measurement of gas/solid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Song Ding; Peng Lihui; Lu Geng; Yang Shiyuan [Tsinghua National Laboratory for Information Science and Technology, Department of Automation, Tsinghua University, Beijing, 100084 (China); Yan Yong, E-mail: lihuipeng@tsinghua.edu.c [University of Kent, Canterbury, Kent CT2 7NT (United Kingdom)

    2009-02-01

    With the rapid growth of the process industry, pneumatic conveying as a tool for the transportation of a wide variety of pulverized and granular materials has become widespread. In order to improve plant control and operational efficiency, it is essential to know the parameters of the particle flow. This paper presents a digital imaging based method which is capable of measuring multiple flow parameters, including volumetric concentration, velocity and mass flow rate of particles in the gas/solid two phase flow. The measurement system consists of a solid state laser for illumination, a low-cost CCD camera for particle image acquisition and a microcomputer with bespoke software for particle image processing. The measurements of particle velocity and volumetric concentration share the same sensing hardware but use different exposure time and different image processing methods. By controlling the exposure time of the camera a clear image and a motion blurred image are obtained respectively. The clear image is thresholded by OTSU method to identify the particles from the dark background so that the volumetric concentration is determined by calculating the ratio between the particle area and the total area. Particle velocity is derived from the motion blur length, which is estimated from the motion blurred images by using the travelling wave equation method. The mass flow rate of particles is calculated by combining the particle velocity and volumetric concentration. Simulation and experiment results indicate that the proposed method is promising for the measurement of multiple parameters of gas/solid two-phase flow.

  3. Graphics processing unit accelerated optical coherence tomography processing at megahertz axial scan rate and high resolution video rate volumetric rendering.

    Science.gov (United States)

    Jian, Yifan; Wong, Kevin; Sarunic, Marinko V

    2013-02-01

    In this report, we describe how to highly optimize a computer unified device architecture based platform to perform real-time processing of optical coherence tomography interferometric data and three-dimensional (3-D) volumetric rendering using a commercially available, cost-effective, graphics processing unit (GPU). The maximum complete attainable axial scan processing rate, including memory transfer and displaying B-scan frame, was 2.24 MHz for 16 bits pixel depth and 2048 fast Fourier transform size; the maximum 3-D volumetric rendering rate, including B-scan, en face view display, and 3-D rendering, was ~23 volumes/second (volume size: 1024×256×200). To the best of our knowledge, this is the fastest processing rate reported to date with a single-chip GPU and the first implementation of real-time video-rate volumetric optical coherence tomography (OCT) processing and rendering that is capable of matching the acquisition rates of ultrahigh-speed OCT.

  4. Graphics processing unit accelerated optical coherence tomography processing at megahertz axial scan rate and high resolution video rate volumetric rendering

    Science.gov (United States)

    Jian, Yifan; Wong, Kevin; Sarunic, Marinko V.

    2013-02-01

    In this report, we describe how to highly optimize a computer unified device architecture based platform to perform real-time processing of optical coherence tomography interferometric data and three-dimensional (3-D) volumetric rendering using a commercially available, cost-effective, graphics processing unit (GPU). The maximum complete attainable axial scan processing rate, including memory transfer and displaying B-scan frame, was 2.24 MHz for 16 bits pixel depth and 2048 fast Fourier transform size; the maximum 3-D volumetric rendering rate, including B-scan, en face view display, and 3-D rendering, was ˜23 volumes/second (volume size: 1024×256×200). To the best of our knowledge, this is the fastest processing rate reported to date with a single-chip GPU and the first implementation of real-time video-rate volumetric optical coherence tomography (OCT) processing and rendering that is capable of matching the acquisition rates of ultrahigh-speed OCT.

  5. Very high frame rate volumetric integration of depth images on mobile devices.

    Science.gov (United States)

    Kähler, Olaf; Adrian Prisacariu, Victor; Yuheng Ren, Carl; Sun, Xin; Torr, Philip; Murray, David

    2015-11-01

    Volumetric methods provide efficient, flexible and simple ways of integrating multiple depth images into a full 3D model. They provide dense and photorealistic 3D reconstructions, and parallelised implementations on GPUs achieve real-time performance on modern graphics hardware. To run such methods on mobile devices, providing users with freedom of movement and instantaneous reconstruction feedback, remains challenging however. In this paper we present a range of modifications to existing volumetric integration methods based on voxel block hashing, considerably improving their performance and making them applicable to tablet computer applications. We present (i) optimisations for the basic data structure, and its allocation and integration; (ii) a highly optimised raycasting pipeline; and (iii) extensions to the camera tracker to incorporate IMU data. In total, our system thus achieves frame rates up 47 Hz on a Nvidia Shield Tablet and 910 Hz on a Nvidia GTX Titan XGPU, or even beyond 1.1 kHz without visualisation.

  6. Preliminary performance analysis of a transverse flow spectrally selective two-slab packed bed volumetric receiver

    CSIR Research Space (South Africa)

    Roos, TH

    2016-05-01

    Full Text Available A new volumetric receiver concept has been investigated, based on an adaptation of the spectrally selective, two-slab packed bed volumetric receiver concept of Flamant et al. Both slabs comprise spheres of identical size – borosilicate...

  7. Columbus Payloads Flow Rate Anomalies

    Science.gov (United States)

    Quaranta, Albino; Bufano, Gaetana; DePalo, Savino; Holt, James M.; Szigetvari, Zoltan; Palumberi, Sergio; Hinderer, S.

    2011-01-01

    The Columbus Active Thermal Control System (ATCS) is the main thermal bus for the pressurized racks working inside the European laboratory. One of the ATCS goals is to provide proper water flow rate to each payload (P/L) by controlling actively the pressure drop across the common plenum distribution piping. Overall flow measurement performed by the Water Pump Assembly (WPA) is the only flow rate monitor available at system level and is not part of the feedback control system. At rack activation the flow rate provided by the system is derived on ground by computing the WPA flow increase. With this approach, several anomalies were raised during these 3 years on-orbit, with the indication of low flow rate conditions on the European racks FSL, BioLab, EDR and EPM. This paper reviews the system and P/Ls calibration approach, the anomalies occurred, the engineering evaluation on the measurement approach and the accuracy improvements proposed, the on-orbit test under evaluation with NASA and finally discusses possible short and long term solutions in case of anomaly confirmation.

  8. In vitro validation of endovascular Doppler-derived flow rates in models of the cerebral circulation.

    Science.gov (United States)

    McGah, P M; Nerva, J D; Morton, R P; Barbour, M C; Levitt, M R; Mourad, P D; Kim, L J; Aliseda, A

    2015-11-01

    This study presents validation of endovascular Doppler velocimetry-based volumetric flow rate measurements conducted in a pulsatile flow loop simulating conditions in both the internal carotid and basilar artery. In vitro models of cerebral vessels, each containing an aneurysm, were fabricated from patient anatomies extracted from 3D rotational angiography. Flow velocity measurements were collected with three different experimental techniques: an endovascular Doppler wire, Particle Image Velocimetry, and a time-resolved ultrasonic flow meter. Womersley's theory of pulsatile flow in a cylindrical vessel was used to compute time-resolved volumetric flow rates from the endovascular Doppler velocity. The volumetric flow rates computed from the Doppler measurements were compared to those from the Particle Image Velocimetry profile measurements, and the direct measurements from the ultrasonic flow meter. The study establishes confidence intervals for any systematic or random errors associated with the wire-derived flow rates as benchmarked to the other two modalities. There is an approximately 10% random error in the Doppler-derived peak and time-averaged flow rates. There is a measurable uniform bias, about 15% too low, in the time-averaged Doppler-derived flow rates. There is also a small proportional bias in the peak systolic Doppler-derived flow rates. Potential sources of error are also discussed.

  9. Volumetric 3-component velocimetry measurements of the flow field on the rear window of a generic car model

    Directory of Open Access Journals (Sweden)

    Tounsi Nabil

    2012-01-01

    Full Text Available Volumetric 3-component Velocimetry measurements are carried out in the flow field around the rear window of a generic car model, the so-called Ahmed body. This particular flow field is known to be highly unsteady, three dimensional and characterized by strong vortices. The volumetric velocity measurements from the present experiments provide the most comprehensive data for this flow field to date. The present study focuses on the wake flow modifications which result from using a simple flow control device, such as the one recently employed by Fourrié et al. [1]. The mean data clearly show the structure of this complex flow and confirm the drag reduction mechanism suggested by Fourrié et al. The results show that strengthening the separated flow leads to weakening the longitudinal vortices and vice versa. The present paper shows that the Volumetric 3-component Velocimetry technique is a powerful tool used for a better understanding of a threedimensional unsteady complex flow such that developing around a bluffbody.

  10. Vitreous flow rates through dual pneumatic cutters: effects of duty cycle and cut rate.

    Science.gov (United States)

    Abulon, Dina Joy K

    2015-01-01

    We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes. The CONSTELLATION(®) Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT(®) vitrectomy probes of each diameter (25+(®), 25, 23, and 20 gauge) operated from 500 cuts per minute (cpm) up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale. At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates. Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration.

  11. Vitreous flow rates through dual pneumatic cutters: effects of duty cycle and cut rate

    Directory of Open Access Journals (Sweden)

    Abulon DJK

    2015-02-01

    Full Text Available Dina Joy K Abulon Medical Affairs, Alcon Research, Ltd, Lake Forest, CA, USA Purpose: We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes. Methods: The CONSTELLATION® Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT® vitrectomy probes of each diameter (25+®, 25, 23, and 20 gauge operated from 500 cuts per minute (cpm up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale. Results: At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates. Conclusion: Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration. Keywords: enhanced 25-gauge vitrectomy, 25-gauge vitrectomy, 20-gauge vitrectomy, 23-gauge vitrectomy, aspiration, Constellation Vision System

  12. Feasibility study of volumetric modulated arc therapy with constant dose rate for endometrial cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ruijie [Department of Radiation Oncology, Peking University Third Hospital, Beijing (China); Wang, Junjie, E-mail: junjiewang47@yahoo.com [Department of Radiation Oncology, Peking University Third Hospital, Beijing (China); Xu, Feng [Department of Biomedical Engineering, Peking University Third Hospital, Beijing (China); Li, Hua [Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing (China); Zhang, Xile [Department of Radiation Oncology, Peking University Third Hospital, Beijing (China)

    2013-10-01

    To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. The nine-field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry run was performed to assess the dosimetric accuracy with MatriXX from IBA. Compared with IMRT, the VMAT-CDR plans delivered a slightly greater V{sub 20} of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability.

  13. Assessment of volumetric-modulated arc therapy for constant and variable dose rates

    Directory of Open Access Journals (Sweden)

    Mariluz De Ornelas-Couto

    2017-01-01

    Full Text Available Purpose: The aim of this study is to compare the effects of dose rate on volumetric-modulated arc therapy plans to determine optimal dose rates for prostate and head and neck (HN cases. Materials and Methods: Ten prostate and ten HN cases were retrospectively studied. For each case, seven plans were generated: one variable dose rate (VDR and six constant dose rate (CDR (100–600 monitor units [MUs]/min plans. Prescription doses were: 80 Gy to planning target volume (PTV for the prostate cases, and 70, 60, and 54 Gy to PTV1, PTV2, and PTV3, respectively, for HN cases. Plans were normalized to 95% of the PTV and PTV1, respectively, with the prescription dose. Plans were assessed using Dose-Volume-Histogram metrics, homogeneity index, conformity index, MUs, and delivery time. Results: For the prostate cases, significant differences were found for rectum D35 between VDR and all CDR plans, except CDR500. Furthermore, VDR was significantly different than CDR100 and 200 for bladder D50. Delivery time for all CDR plans and MUs for CDR400–600 were significantly higher when compared to VDR. HN cases showed significant differences between VDR and CDR100, 500 and 600 for D2 to the cord and brainstem. Significant differences were found for delivery time and MUs for all CDR plans, except CDR100 for number of MUs. Conclusion: The most significant differences were observed in delivery time and number of MUs. All-in-all, the best CDR for prostate cases was found to be 300 MUs/min and 200 or 300 MUs/min for HN cases. However, VDR plans are still the choice in terms of MU efficiency and plan quality.

  14. Modeling Flow Rate to Estimate Hydraulic Conductivity in a Parabolic Ceramic Water Filter

    Directory of Open Access Journals (Sweden)

    Ileana Wald

    2012-01-01

    Full Text Available In this project we model volumetric flow rate through a parabolic ceramic water filter (CWF to determine how quickly it can process water while still improving its quality. The volumetric flow rate is dependent upon the pore size of the filter, the surface area, and the height of water in the filter (hydraulic head. We derive differential equations governing this flow from the conservation of mass principle and Darcy's Law and find the flow rate with respect to time. We then use methods of calculus to find optimal specifications for the filter. This work is related to the research conducted in Dr. James R. Mihelcic's Civil and Environmental Engineering Lab at USF.

  15. HANARO core channel flow-rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Tae; Im, Don Soon; Kim, Seon Duk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    HANARO core consists of 23 hexagonal flow tubes and 16 cylindrical flow tubes. To get the core flow distribution, we used 6 flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies). The differential pressures were measured and converted to flow-rates using the predetermined relationship between AP and flow-rate for each instrumented dummy fuel assemblies. The flow-rate for the cylindrical flow channels shows +-7% relative errors and that for the hexagonal flow channels shows +-3.5% relative errors. Generally the flow-rates of outer core channels show smaller values compared to those of inner core. The channels near to the core inlet pipe and outlet pipes also show somewhat lower flow-rates. For the lower flow channels, the thermal margin was checked by considering complete linear power histories. From the experimental results, the gap flow-rate was estimated to be 49.4 kg/s (cf. design flow of 50 kg/s). 15 tabs., 9 figs., 10 refs. (Author) .new.

  16. Volumetric 3-D Vector Flow Measurements using a 62+62 Row-Column Addressed Array

    DEFF Research Database (Denmark)

    Holbek, Simon; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2017-01-01

    Experimental results from volumetric 3-D vector flow measurements using a 62+62 row-column addressed (RCA) array are presented. A plane-by-plane steered transmit sequence and its post processing steps are described for obtaining 3-D vector flow in a volume. A modified version of the transverse...

  17. Follow-up after gamma knife radiosurgery for vestibular schwannomas: volumetric and axial control rates

    NARCIS (Netherlands)

    Timmer, F.C.A.; Hanssens, P.E.; Haren, A.E. van; Overbeeke, J.J. van; Mulder, J.J.S.; Cremers, C.W.R.J.; Graamans, K.

    2011-01-01

    OBJECTIVES/HYPOTHESIS: A prospective long-term follow-up study was conducted to evaluate the results of gamma knife radiosurgery (GKRS) for vestibular schwannoma (VS) patients. Both axial and volumetric measurements are used to determine tumor size during follow-up. STUDY DESIGN: Individual

  18. Coriolis mass flow rate meters for low flows

    NARCIS (Netherlands)

    Mehendale, A.

    2008-01-01

    The accurate and quick measurement of small mass flow rates (~10 mg/s) of fluids is considered an “enabling technology��? in semiconductor, fine-chemical, and food & drugs industries. Flowmeters based on the Coriolis effect offer the most direct sensing of the mass flow rate, and for this reason do

  19. Flexible Membrane Micro Flow-rate Threshold Flow Sensor

    Directory of Open Access Journals (Sweden)

    Hee C. LIM

    2007-12-01

    Full Text Available A piezoresistive flow sensor that functions as a threshold flow switch, independent of input supply voltage, is designed, fabricated, and tested. The test flow rate is in the 10s ml/hr range. The sensor is fabricated using doped hydrogenated amorphous silicon thin film with MEMs on flexible polyimide substrate. The flow sensor is highly sensitive and able to distinguish between distilled water and 0.1 % NaCl saline solution in terms of threshold switch-on flow rate. The switch-on threshold of the flow sensor is observed to be independent of the applied input voltage. These turn-on threshold levels are adaptable to user’s application.

  20. Stability of flow focusing: The minimum attainable flow rate

    Science.gov (United States)

    Montanero, J. M.; Rebollo, N.; Acero, A.; Ferrera, C.; Herrada, M. A.; Ganan-Calvo, A. M.

    2011-11-01

    We analyze both theoretically and experimentally the stability of the steady jetting regime reached when liquid jets are focused by coaxial gas streams. In the low-viscosity case, viscous dissipation in the feeding capillary and liquid meniscus seem to be the origin of the instability. For high-viscosity liquids, the breakdown of the jetting regime takes place when the pressure drop cannot overcome the resistance force offered by surface tension. The characteristic flow rates for which the tapering menisci become unstable do not depend on the pressure drop applied to the system to produce the micro-jet. They increase (decrease) with viscosity for very low (high) viscosity liquids. Experiments confirmed the validity of the above conclusions. For each applied pressure drop, there is a minimum liquid flow rate below which the liquid meniscus drips. The minimum flow rates become practically independent of the applied pressure drop for sufficiently large values of this quantity. There exists an optimum value of the capillary-to-orifice distance for which the minimum flow rate attains a limiting value, which constitutes the lowest flow rate attainable with a given configuration in the steady jetting regime. A two-dimensional stability map with a high degree of validity is plotted on the plane defined by the Reynolds and capillary numbers based on the limiting flow rate.

  1. Flow rate measurements by means of tracers

    Energy Technology Data Exchange (ETDEWEB)

    Mosetti, F. (Trieste Univ. (Italy). Istituto di Geodesia e Geofisica)

    The application of some sources of diffusion for the flow rate measurement of water or other fluids is here presented. The laminar instantaneous source, obtained in practice with easy devices, is very useful in river or channel measurements. The analysis of the measurements could supply the flow rate and the presence of water losses or recharges. The section of the channel can also be determined by such a method.

  2. Optimum solar collector fluid flow rates

    DEFF Research Database (Denmark)

    Furbo, Simon; Shah, Louise Jivan

    1996-01-01

    Experiments showed that by means of a standard electronically controlled pump, type UPE 2000 from Grundfos it is possible to control the flow rate in a solar collector loop in such a way that the flow rate is strongly influenced by the temperature of the solar collector fluid passing the pump...... the energy consumption of a normal ciculation pump in the solar heating system.Calculations showed that the highest thermal performances for small SDHW systems based on mantle tanks with constant volume flow rates in the solar collector loops are achieved if the flow rate is situated in the interval from 0.......2 to 0.3 l/min. per m^2 solar collector for combi tank systems and in the interval from 0.3 to 0.4 l/min. per m^2 solar collector for preheating systems. Further, calculations showed that by means of an advanced control strategy for the flow rate - for instance if the flow rate is directly proportional...

  3. Ultrasonic rate measurement of multiphase flow

    Science.gov (United States)

    Dannert, David A.; Horne, Roland N.

    1993-01-01

    One of the most important tools in production logging and well testing is the downhole flowmeter. Unfortunately, existing tools are inaccurate outside of an idealized single phase flow regime. Spinner tools are inaccurate at extremely high or low flow rates and when the flow rate is variable. Radioactive tracer tools have similar inaccuracies and are extremely sensitive to the flow regime. Both tools completely fail in the presence of multiphase flow, whether for gas/oil, gas/water, or fluid/solid. Downhole flowmetering is important for locating producing zones and thief zones and monitoring production and injection rates. The effects of stimulation can also be determined. The goal of this project is the investigation of accurate downhole flowmetering techniques for all single phase flow regimes and multiphase flows. The measurement method investigated in this report is the use of ultrasound. There are two ways to use ultrasound for fluid velocity measurement. The first method, examined in Chapter 2, is the contrapropagation, or transit-time, method which compares travel times with and against fluid flow. Chapter 3 details the second method which measures the Doppler frequency shift of a reflected sound wave in the moving fluid. Both of these technologies need to be incorporated in order to build a true multiphase flowmeter. Chapter 4 describes the proposed downhole multiphase flowmeter.

  4. Volumetric TAN Conversion Rate - Reduction in Energy Consumption Using Moving Bed Biofilter

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Land-based reuse systems offer many advantages over netpens or flow-through systems. This includes reduced siting problems, better control of water quality, and...

  5. Flow rates for sharp-edged orifices

    Science.gov (United States)

    Groesbeck, W. A.; Manning, F. L.

    1975-01-01

    Two charts are proposed for calculating the flow coefficient and the area correction factor used in the equation for the flow rate through a sharp-edged orifice. The proposed charts account for variations in the discharge coefficient of sharp-edged orifices and can be used with any pressure ratio for both subcritical and supercritical flow conditions. They can also be used for any gas by using the appropriate gas constant and ratio of specific heats. The application of the charts is illustrated by examples.

  6. Controlling a wide range of flow rates

    Science.gov (United States)

    Perkins, G. S.

    1979-01-01

    Servo-operated valve and two flowmeters allow accurate control over 1,900:1 flow-rate range. It was developed as part of laboratory instrument for measuring properties of confined fluids under conditions analogous to those encountered in deep drilling operations.

  7. Volumetric flow imaging reveals the importance of vortex ring formation in squid swimming tail-first and arms-first.

    Science.gov (United States)

    Bartol, Ian K; Krueger, Paul S; Jastrebsky, Rachel A; Williams, Sheila; Thompson, Joseph T

    2016-02-01

    Squids use a pulsed jet and fin movements to swim both arms-first (forward) and tail-first (backward). Given the complexity of the squid multi-propulsor system, 3D velocimetry techniques are required for the comprehensive study of wake dynamics. Defocusing digital particle tracking velocimetry, a volumetric velocimetry technique, and high-speed videography were used to study arms-first and tail-first swimming of brief squid Lolliguncula brevis over a broad range of speeds [0-10 dorsal mantle lengths (DML) s(-1)] in a swim tunnel. Although there was considerable complexity in the wakes of these multi-propulsor swimmers, 3D vortex rings and their derivatives were prominent reoccurring features during both tail-first and arms-first swimming, with the greatest jet and fin flow complexity occurring at intermediate speeds (1.5-3.0 DML s(-1)). The jet generally produced the majority of thrust during rectilinear swimming, increasing in relative importance with speed, and the fins provided no thrust at speeds >4.5 DML s(-1). For both swimming orientations, the fins sometimes acted as stabilizers, producing negative thrust (drag), and consistently provided lift at low/intermediate speeds (swimming orientation, and η for swimming sequences with clear isolated jet vortex rings was significantly greater (η=78.6±7.6%, mean±s.d.) than that for swimming sequences with clear elongated regions of concentrated jet vorticity (η=67.9±19.2%). This study reveals the complexity of 3D vortex wake flows produced by nekton with hydrodynamically distinct propulsors. © 2016. Published by The Company of Biologists Ltd.

  8. New findings on the minimum flow rate in Flow Focusing

    Science.gov (United States)

    Bluth, Benjamin; Ganan-Calvo, Alfonso M.

    2006-11-01

    Recently published works on spatial-temporal instability analyses have dealt with flow-focused micro-jets. Those works have revealed that the minimum rate of fluid that can be focused is, in many cases, linked to an absolute/convective instability transition of the focused fluid micro-jet. Further to this, a series of very recent experiments indicate that the minimum flow rate may result very plausibly from the breakdown of a stability ``chain'', a link of it --and possibly not the weakest one- being the micro jet. The dripping-jetting transition curves in the Reynolds-Weber parametrical space show a conspicuous, consistent and interesting turning point. Whether this behaviour reflects a possible cross-over between the instability of the jet and that of the cusp-like meniscus is here discussed. Indeed, these new results are now set in perspective along with those recently published ones.

  9. Volumetric flow imaging reveals the importance of vortex ring formation in squid swimming tail-first and arms-first

    National Research Council Canada - National Science Library

    Bartol, Ian K; Krueger, Paul S; Jastrebsky, Rachel A; Williams, Sheila; Thompson, Joseph T

    2016-01-01

    .... Defocusing digital particle tracking velocimetry, a volumetric velocimetry technique, and high-speed videography were used to study arms-first and tail-first swimming of brief squid Lolliguncula...

  10. Megahertz rate, volumetric imaging of bubble clouds in sonothrombolysis using a sparse hemispherical receiver array

    Science.gov (United States)

    Acconcia, Christopher N.; Jones, Ryan M.; Goertz, David E.; O'Reilly, Meaghan A.; Hynynen, Kullervo

    2017-09-01

    It is well established that high intensity focused ultrasound can be used to disintegrate clots. This approach has the potential to rapidly and noninvasively resolve clot causing occlusions in cardiovascular diseases such as deep vein thrombosis (DVT). However, lack of an appropriate treatment monitoring tool is currently a limiting factor in its widespread adoption. Here we conduct cavitation imaging with a large aperture, sparse hemispherical receiver array during sonothrombolysis with multi-cycle burst exposures (0.1 or 1 ms burst lengths) at 1.51 MHz. It was found that bubble cloud generation on imaging correlated with the locations of clot degradation, as identified with high frequency (30 MHz) ultrasound following exposures. 3D images could be formed at integration times as short as 1 µs, revealing the initiation and rapid development of cavitation clouds. Equating to megahertz frame rates, this is an order of magnitude faster than any other imaging technique available for in vivo application. Collectively, these results suggest that the development of a device to perform DVT therapy procedures would benefit greatly from the integration of receivers tailored to bubble activity imaging.

  11. 3D Volumetric Measurements of GH Secreting Adenomas Correlate with Baseline Pituitary Function, Initial Surgery Success Rate, and Disease Control.

    Science.gov (United States)

    Tirosh, Amit; Papadakis, Georgios Z; Chittiboina, Prashant; Lyssikatos, Charalampos; Belyavskaya, Elena; Keil, Meg; Lodish, Maya B; Stratakis, Constantine A

    2017-06-01

    There is scarce data on the clinical utility of volume measurement for growth hormone (GH)-secreting pituitary adenomas. The current study objective was to assess the association between pituitary adenoma volumes and baseline endocrine evaluation, initial surgical success rate, and disease control among patients with acromegaly. A retrospective cohort study was conducted at a clinical research center including patients with acromegaly due to GH-secreting pituitary adenomas. Baseline hormonal evaluation and adenoma characteristics according to MRI were collected. Volumetric measurements of pituitary adenomas were performed using a semi-automated lesion segmentation and tumor-volume assessment tools. Rates of post-operative medical treatment, radiation therapy, and re-operation were gathered from the patients' medical records. Twenty seven patients (11 females) were included, median age 21.0 years (interquartile range 29 years, range 3-61 years). Patients harboring adenomas with a volume <2 000 mm 3 had higher chance to achieve disease remission [94.1% (n=16) vs. 50.0% (n=4), p<0.05]. Adenoma volumes positively correlated with baseline plasma GH levels before and after oral glucose administration, and with plasma IGF-I and PRL levels. Adenoma volume had negative correlation with morning plasma cortisol levels. Finally, patients harboring larger adenomas required 2nd surgery and/or medical treatment more often compared with subjects with smaller adenomas. Accurate 3D volume measurement of GH-secreting pituitary adenomas may be used for the prediction of initial surgery success and for disease control rates among patients with a GH-secreting pituitary adenomas and performs better than standard size assessments. © Georg Thieme Verlag KG Stuttgart · New York.

  12. SU-E-T-421: Feasibility Study of Volumetric Modulated Arc Therapy with Constant Dose Rate for Endometrial Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Wang, J [Peking University Third Hospital, Beijing, Beijing (China)

    2014-06-01

    Purpose: To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. Methods: The nine-Field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry Run was performed to assess the dosimetric accuracy with MatriXX from IBA. Results: Compared with IMRT, the VMAT-CDR plans delivered a slightly greater V20 of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs Decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. Conclusion: VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability. This work is supported by the grant project, National Natural; Science Foundation of China (No. 81071237)

  13. Reproducibility of Volumetric Computed Tomography of Stable Small Pulmonary Nodules with Implications on Estimated Growth Rate and Optimal Scan Interval.

    Directory of Open Access Journals (Sweden)

    Gary T Smith

    Full Text Available To use clinically measured reproducibility of volumetric CT (vCT of lung nodules to estimate error in nodule growth rate in order to determine optimal scan interval for patient follow-up.We performed quantitative vCT on 89 stable non-calcified nodules and 49 calcified nodules measuring 3-13 mm diameter in 71 patients who underwent 3-9 repeat vCT studies for clinical evaluation of pulmonary nodules. Calculated volume standard deviation as a function of mean nodule volume was used to compute error in estimated growth rate. This error was then used to determine the optimal patient follow-up scan interval while fixing the false positive rate at 5%.Linear regression of nodule volume standard deviation versus the mean nodule volume for stable non-calcified nodules yielded a slope of 0.057 ± 0.002 (r2 = 0.79, p<0.001. For calcified stable nodules, the regression slope was 0.052 ± 0.005 (r2 = 0.65, p = 0.03. Using this with the error propagation formula, the optimal patient follow-up scan interval was calculated to be 81 days, independent of initial nodule volume.Reproducibility of vCT is excellent, and the standard error is proportional to the mean calculated nodule volume for the range of nodules examined. This relationship constrains statistical certainty of vCT calculated doubling times and results in an optimal scan interval that is independent of the initial nodule volume.

  14. Electromechanically Actuated Valve for Controlling Flow Rate

    Science.gov (United States)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  15. Peak expiratory flow rate and Pulse Pressure values during the ...

    African Journals Online (AJOL)

    This study assessed the peak expiratory flow rate and pulse pressure during the luteal and menstruation phases of the menstrual cycle. The peak expiratory flow rate and pulse pressure were measured using the Wright's Peak Flow Meter and Mercury Sphygmomanometer respectively. The peak expiratory flow rate and ...

  16. Solids flow rate measurement in dense slurries

    Energy Technology Data Exchange (ETDEWEB)

    Porges, K.G.; Doss, E.D.

    1993-09-01

    Accurate and rapid flow rate measurement of solids in dense slurries remains an unsolved technical problem, with important industrial applications in chemical processing plants and long-distance solids conveyance. In a hostile two-phase medium, such a measurement calls for two independent parameter determinations, both by non-intrusive means. Typically, dense slurries tend to flow in laminar, non-Newtonian mode, eliminating most conventional means that usually rely on calibration (which becomes more difficult and costly for high pressure and temperature media). These issues are reviewed, and specific solutions are recommended in this report. Detailed calculations that lead to improved measuring device designs are presented for both bulk density and average velocity measurements. Cross-correlation, chosen here for the latter task, has long been too inaccurate for practical applications. The cause and the cure of this deficiency are discussed using theory-supported modeling. Fluid Mechanics are used to develop the velocity profiles of laminar non-Newtonian flow in a rectangular duct. This geometry uniquely allows the design of highly accurate `capacitive` devices and also lends itself to gamma transmission densitometry on an absolute basis. An absolute readout, though of less accuracy, is also available from a capacitive densitometer and a pair of capacitive sensors yields signals suitable for cross-correlation velocity measurement.

  17. Tidal Volume and Instantaneous Respiration Rate Estimation using a Volumetric Surrogate Signal Acquired via a Smartphone Camera.

    Science.gov (United States)

    Reyes, Bersain A; Reljin, Natasa; Kong, Youngsun; Nam, Yunyoung; Chon, Ki H

    2017-05-01

    Two parameters that a breathing status monitor should provide include tidal volume ( VT) and respiration rate (RR). Recently, we implemented an optical monitoring approach that tracks chest wall movements directly on a smartphone. In this paper, we explore the use of such noncontact optical monitoring to obtain a volumetric surrogate signal, via analysis of intensity changes in the video channels caused by the chest wall movements during breathing, in order to provide not only average RR but also information about VT and to track RR at each time instant (IRR). The algorithm, implemented on an Android smartphone, is used to analyze the video information from the smartphone's camera and provide in real time the chest movement signal from N = 15 healthy volunteers, each breathing at VT ranging from 300 mL to 3 L. These measurements are performed separately for each volunteer. Simultaneous recording of volume signals from a spirometer is regarded as reference. A highly linear relationship between peak-to-peak amplitude of the smartphone-acquired chest movement signal and spirometer VT is found ( r2 = 0.951 ±0.042, mean ± SD). After calibration on a subject-by-subject basis, no statistically significant bias is found in terms of VT estimation; the 95% limits of agreement are -0.348 to 0.376 L, and the root-mean-square error (RMSE) was 0.182 ±0.107 L. In terms of IRR estimation, a highly linear relation between smartphone estimates and the spirometer reference was found ( r2 = 0.999 ±0.002). The bias, 95% limits of agreement, and RMSE are -0.024 breaths-per-minute (bpm), -0.850 to 0.802 bpm, and 0.414 ±0.178 bpm, respectively. These promising results show the feasibility of developing an inexpensive and portable breathing monitor, which could provide information about IRR as well as VT, when calibrated on an individual basis, using smartphones. Further studies are required to enable practical implementation of the proposed approach.

  18. In Vivo Three-Dimensional Velocity Vector Imaging and Volumetric Flow Rate Measurements

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev

    2013-01-01

    The three-dimensional (3-D) Transverse Oscillation (TO) method is used to obtain 3-D velocity vector estimates in two orthogonal planes. The method is suitable for a real-time implementation. Data are acquired using a Vermon 3.0 MHz 32x32 element 2-D phased array and the experimental ultrasound s...

  19. Hypersonic Air Flow with Finite Rate Chemistry

    National Research Council Canada - National Science Library

    Boyd, Ian

    1997-01-01

    ... describe the effects of non-equilibrium flow chemistry, shock interaction, and turbulent mixing and combustion on the performance of vehicles and air breathing engines designed to fly in the hypersonic flow...

  20. Ni foam cathode enables high volumetric H2 production in a microbial electrolysis cell

    NARCIS (Netherlands)

    Jeremiasse, A.W.; Hamelers, H.V.M.; Saakes, M.; Buisman, C.J.N.

    2010-01-01

    Valuable, “green” H2 can be produced with a microbial electrolysis cell (MEC). To achieve a high volumetric production rate of high purity H2, a continuous flow MEC with an anion exchange membrane, a flow through bioanode and a flow through Ni foam cathode was constructed. At an electrical energy

  1. Empirical Constraints on the Origin of Fast Radio Bursts: Volumetric Rates and Host Galaxy Demographics as a Test of Millisecond Magnetar Connection

    Science.gov (United States)

    Nicholl, M.; Williams, P. K. G.; Berger, E.; Villar, V. A.; Alexander, K. D.; Eftekhari, T.; Metzger, B. D.

    2017-07-01

    The localization of the repeating fast radio burst (FRB) 121102 to a low-metallicity dwarf galaxy at z = 0.193, and its association with a luminous quiescent radio source, suggests the possibility that FRBs originate from magnetars, formed by the unusual supernovae that occur in such galaxies. We investigate this possibility via a comparison of magnetar birth rates, the FRB volumetric rate, and host galaxy demographics. We calculate average volumetric rates of possible millisecond magnetar production channels, such as superluminous supernovae (SLSNe), long and short gamma-ray bursts (GRBs), and general magnetar production via core-collapse supernovae (CCSNe). For each channel, we also explore the expected host galaxy demographics using their known properties. We determine for the first time the number density of FRB emitters (the product of their volumetric birth rate and lifetime), {R}{FRB}τ ≈ {10}4 Gpc-3, assuming that FRBs are predominantly emitted from repetitive sources similar to FRB 121102 and adopting a beaming factor of 0.1. By comparing rates, we find that production via rare channels (SLSNe, GRBs) implies a typical FRB lifetime of ˜30-300 years, in good agreement with other lines of argument. The total energy emitted over this time is consistent with the available energy stored in the magnetic field. On the other hand, any relation to magnetars produced via normal CCSNe leads to a very short lifetime of ˜0.5 years, in conflict with both theory and observation. We demonstrate that due to the diverse host galaxy distributions of the different progenitor channels, many possible sources of FRB birth can be ruled out with ≲ 10 host galaxy identifications. Conversely, targeted searches of galaxies that have previously hosted decades-old SLSNe and GRBs may be a fruitful strategy for discovering new FRBs and related quiescent radio sources, and determining the nature of their progenitors.

  2. Milk Flow Rates from bottle nipples used after hospital discharge.

    Science.gov (United States)

    Pados, Britt Frisk; Park, Jinhee; Thoyre, Suzanne M; Estrem, Hayley; Nix, W Brant

    To test the milk flow rates and variability in flow rates of bottle nipples used after hospital discharge. Twenty-six nipple types that represented 15 common brands as well as variety in price per nipple and store location sold (e.g., Babies R' Us, Walmart, Dollar Store) were chosen for testing. Ten of each nipple type (n = 260 total) were tested by measuring the amount of infant formula expressed in 1 minute using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated. Flow rates of nipples within brand were compared statistically. Milk flow rates varied from 1.68 mL/min for the Avent Natural Newborn Flow to 85.34 mL/min for the Dr. Brown's Standard Y-cut. Variability between nipple types also varied widely, from .03 for the Dr. Brown's Standard Level 3 to .37 for MAM Nipple 1 Slow Flow. The extreme range of milk flow rates found may be significant for medically fragile infants being discharged home who are continuing to develop oral feeding skills. The name of the nipple does not provide clear information about the flow rate to guide parents in decision making. Variability in flow rates within nipples of the same type may complicate oral feeding for the medically fragile infant who may not be able to adapt easily to change in flow rates. Both flow rate and variability should be considered when guiding parents to a nipple choice.

  3. Experimental investigation of the liquid volumetric mass transfer coefficient for upward gas-liquid two-phase flow in rectangular microchannels

    Directory of Open Access Journals (Sweden)

    X. Y. Ji

    2010-12-01

    Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.

  4. Higher flow rates improve heating during hyperthermic intraperitoneal chemoperfusion.

    Science.gov (United States)

    Furman, Matthew J; Picotte, Robert J; Wante, Mark J; Rajeshkumar, Barur R; Whalen, Giles F; Lambert, Laura A

    2014-12-01

    Heated intraperitoneal chemotherapy (HIPEC) kills cancer cells via thermal injury and improved chemotherapeutic cytotoxicity. We hypothesize that higher HIPEC flow rates improve peritoneal heating and HIPEC efficacy. (1) A HIPEC-model (30.8 L cooler with attached extracorporeal pump) was filled with 37°C water containing a suspended 1 L saline bag (SB) wrapped in a cooling sleeve, creating a constant heat sink. (2) HIPECs were performed in a swine model. Inflow, outflow, and peritoneal temperatures were monitored as flow rates varied. (3) Flow rates and temperatures during 20 HIPECs were reviewed. Higher flow rates decreased time required to increase water bath (WB) and SB temperature to 43°C. With a constant heat sink, the minimum flow rate required to reach 43°C in the WB was 1.75 L/min. Higher flow rates lead to greater temperature gradients between the WB and SB. In the swine model, the minimum flow rate required to reach 43°C outflow was 2.5-3.0 L/min. Higher flows led to more rapid heating of the peritoneum and greater peritoneal/outflow temperature gradients. Increased flow during clinical HIPEC suggested improved peritoneal heating with lower average visceral temperatures. There is a minimum flow rate required to reach goal temperature during HIPEC. Flow rate is an important variable in achieving and maintaining goal temperatures during HIPEC. © 2014 Wiley Periodicals, Inc.

  5. Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer.

    Science.gov (United States)

    Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

    2016-01-01

    To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D90 of 34Gy in 8.5Gy per fraction, and 145Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2Gy per fraction, EQD2) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The Dmean (EQD2) of rectum decreased 22.36Gy in HDR and 17.01Gy in LDR from 30.24Gy in VMAT, respectively. The Dmean (EQD2) of bladder decreased 6.91Gy in HDR and 2.53Gy in LDR from 13.46Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD2) was 80.26, 70.23, and 104.91Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  6. A longitudinal observational study of brain atrophy rate reflecting four decades of multiple sclerosis: a comparison of serial 1D, 2D, and volumetric measurements from MRI images

    Energy Technology Data Exchange (ETDEWEB)

    Martola, Juha; Zhang, Yi; Aspelin, Peter; Kristoffersen Wiberg, Maria [Karolinska Institutet, Division of Radiology, Department of Clinical Science, Intervention, and Technology, Stockholm (Sweden); Bergstroem, Jakob [Karolinska Institutet, The Medical Statistics Unit, Department of Learning, Informatics, Management and Ethics (LIME), Stockholm (Sweden); Fredrikson, Sten; Stawiarz, Leszek; Hillert, Jan [Karolinska Institutet, Division of Neurology, Department of Clinical Neuroscience, Stockholm (Sweden); Flodmark, Olof; Lilja, Anders [Karolinska University Hospital, Department of Neuroradiology, Department of Clinical Neuroscience, Stockholm (Sweden); Ekbom, Anders [Karolinska Institutet, Clinical Epidemiology Unit, Stockholm (Sweden)

    2010-02-15

    Multiple sclerosis (MS) has a variable progression with an early onset of atrophy. Individual longitudinal radiological evaluations (over decades) are difficult to perform due to the limited availability of magnetic resonance imaging (MRI) in the past, patients lost in follow-up, and the continuous updating of scanners. We studied a cohort with widespread disease duration at baseline. The observed individual atrophy rates over time of 10 years represented four decades of disease span. Thirty-seven MS patients (age range 24-65 years with disease duration 1-33 years) were consecutively selected and evaluated with MRI at baseline 1995 and in 1996. They were followed up for a decade (mean of 9.25 years, range 7.3-10 years) up to 2003-2005. Brain parenchymal volume and volumes of the supratentorial ventricles were analyzed with semi-automated volumetric measurements at three time points (1995, 1996, and 2003-2005). Volumetric differences were found over shorter periods of time (1-7 months); however, differences vanished by the end of follow-up. A uniform longitudinal decrease in brain volume and increase in ventricle volumes were found. Frontal horn width (1D) correlated strongest to 3D measures. No statistical differences of atrophy rates between MS courses were found. Supratentorial ventricular volumes were associated with disability and this association persisted during follow-up. Despite variable clinical courses, the degenerative effects of MS progression expressed in brain atrophy seem to uniformly progress over longer periods of time. These volumetric changes can be detected using 1D and 2D measurements performed on a routine PACS workstation. (orig.)

  7. Milk flow rates from bottle nipples used after hospital discharge

    Science.gov (United States)

    Pados, Britt Frisk; Park, Jinhee; Thoyre, Suzanne M.; Estrem, Hayley; Nix, W. Brant

    2016-01-01

    Purpose To test the milk flow rates and variability in flow rates of bottle nipples used after hospital discharge. Study Design and Methods Twenty-six nipple types that represented 15 common brands as well as variety in price per nipple and store location sold (e.g., Babies R’ Us, Walmart, Dollar Store) were chosen for testing. Ten of each nipple type (n=260 total) were tested by measuring the amount of infant formula expressed in one minute using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated. Flow rates of nipples within brand were compared statistically. Results Milk flow rates varied from 1.68 mL/min for the Avent Natural Newborn Flow to 85.34 mL/min for the Dr. Brown’s Standard Y-cut. Variability between nipple types also varied widely, from .03 for the Dr. Brown’s Standard Level 3 to .37 for MAM Nipple 1 Slow Flow. Clinical Implications The extreme range of milk flow rates found may be significant for medically fragile infants being discharged home who are continuing to develop oral feeding skills. The name of the nipple does not provide clear information about the flow rate to guide parents in decision-making. Variability in flow rates within nipples of the same type may complicate oral feeding for the medically fragile infant who may not be able to adapt easily to change in flow rates. Both flow rate and variability should be considered when guiding parents to a nipple choice. PMID:27008466

  8. Peak Expiratory Flow Rate In Cigarette Smokers | Ukoli | Highland ...

    African Journals Online (AJOL)

    Objective: To compare lung function between smokers and non-smokers using Peak Expiratory Flow Rate (PEFR). Methods: This study examines the peak expiratory flow rate (PEFR) of three hundred and forty cigarette smokers, age and sex-matched with PEFR of equal number of non-smokers. Results: The mean PEFR of ...

  9. GROWTH RATE DISTRIBUTION OF BORAX SINGLE CRYSTALS ON THE (001 FACE UNDER VARIOUS FLOW RATES

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax single crystals from aqueous solutions at various flow rates in the (001 direction were measured using in situ cell method. From the growth rate data obtained, the growth rate distribution of borax crystals was investigated using Minitab Software and SPSS Software at relative supersaturation of 0807 and temperature of 25 °C. The result shows that normal, gamma, and log-normal distribution give a reasonably good fit to GRD. However, there is no correlation between growth rate distribution and flow rate of solution.   Keywords: growth rate dispersion (GRD, borax, flow rate

  10. Responses of prawn to water flow rates

    Energy Technology Data Exchange (ETDEWEB)

    Vascotto, G.L.; Nilas, P.U.

    1987-05-28

    An aquarium study to determine the responses of postlarval macrobrachium rosenbergii to varying water changes was carried out. Six week old postlarvae were raised in glass aquaria receiving 0, 1.15, 7.2 and 14.4 water changes per day over a 12 week period. The treatments had significant influences on survival, biomass, and average size of the animals. Maximum survival and highest biomass were found in the 1.15 water turnover treatment; however, this treatment also produced the smallest average size animals. Early high mortalities were attributed to poor growing conditions in the high and low flow treatments, while later mortality appeared to be biomass dependent.

  11. Performance of high flow rate samplers for respirable particle collection.

    Science.gov (United States)

    Lee, Taekhee; Kim, Seung Won; Chisholm, William P; Slaven, James; Harper, Martin

    2010-08-01

    The American Conference of Governmental Industrial hygienists (ACGIH) lowered the threshold limit value (TLV) for respirable crystalline silica (RCS) exposure from 0.05 to 0.025 mg m(-3) in 2006. For a working environment with an airborne dust concentration near this lowered TLV, the sample collected with current standard respirable aerosol samplers might not provide enough RCS for quantitative analysis. Adopting high flow rate sampling devices for respirable dust containing silica may provide a sufficient amount of RCS to be above the limit of quantification even for samples collected for less than full shift. The performances of three high flow rate respirable samplers (CIP10-R, GK2.69, and FSP10) have been evaluated in this study. Eleven different sizes of monodisperse aerosols of ammonium fluorescein were generated with a vibrating orifice aerosol generator in a calm air chamber in order to determine the sampling efficiency of each sampler. Aluminum oxide particles generated by a fluidized bed aerosol generator were used to test (i) the uniformity of a modified calm air chamber, (ii) the effect of loading on the sampling efficiency, and (iii) the performance of dust collection compared to lower flow rate cyclones in common use in the USA (10-mm nylon and Higgins-Dewell cyclones). The coefficient of variation for eight simultaneous samples in the modified calm air chamber ranged from 1.9 to 6.1% for triplicate measures of three different aerosols. The 50% cutoff size ((50)d(ae)) of the high flow rate samplers operated at the flow rates recommended by manufacturers were determined as 4.7, 4.1, and 4.8 microm for CIP10-R, GK2.69, and FSP10, respectively. The mass concentration ratio of the high flow rate samplers to the low flow rate cyclones decreased with decreasing mass median aerodynamic diameter (MMAD) and high flow rate samplers collected more dust than low flow rate samplers by a range of 2-11 times based on gravimetric analysis. Dust loading inside the

  12. Increased flow resistance and decreased flow rate in patients with acute respiratory distress syndrome: The role of autonomic nervous modulation

    Directory of Open Access Journals (Sweden)

    I-Chen Chen

    2016-01-01

    Conclusion: The flow rate is decreased and the flow resistance increased in patients with ARDS. PEEP is one of the causes of increased flow resistance and decreased flow rate in patients with ARDS. Another cause of decreased flow rate and increased flow resistance in ARDS patients is the increased vagal activity and decreased sympathetic activity. The monitoring of flow rate and flow resistance during mechanical ventilation might be useful for the proper management of ARDS patients.

  13. Large-scale volumetric flow measurement in a pure thermal plume by dense tracking of helium-filled soap bubbles

    Science.gov (United States)

    Huhn, Florian; Schanz, Daniel; Gesemann, Sebastian; Dierksheide, Uwe; van de Meerendonk, Remco; Schröder, Andreas

    2017-09-01

    We present a spatially and temporally highly resolved flow measurement covering a large volume ( 0.6 m3) in a pure thermal plume in air. The thermal plume develops above an extended heat source and is characterized by moderate velocities ( U 0.35 m/s) with a Reynolds number of Re ˜ 500 and a Rayleigh number of {Ra}˜ 106. We demonstrate the requirements and capabilities of the measurement equipment and the particle tracking approach to be able to probe measurement volumes up to and beyond one cubic meter. The use of large tracer particles (300 μm), helium-filled soap bubbles (HFSBs), is crucial and yields high particle image quality over large-volume depths when illuminated with arrays of pulsed high-power LEDs. The experimental limitations of the HFSBs—their limited lifetime and their intensity loss over time—are quantified. The HFSBs' uniform particle images allows an accurate reconstruction of the flow using Shake-The-Box particle tracking with high particle concentrations up to 0.1 particles per pixel. This enables tracking of up to 275,000 HFSBs simultaneously. After interpolating the scattered data onto a regular grid with a Navier-Stokes regularization, the velocity field of the thermal plume reveals a multitude of vortices with a smooth temporal evolution and a remarkable coherence in time (see animation, supplementary data). Acceleration fields are also derived from interpolated particle tracks and complement the flow measurement. Additionally, the flow map, the basis of a large class of Lagrangian coherent structures, is computed directly from observed particle tracks. We show entrainment regions and coherent vortices of the thermal plume in the flow map and compute fields of the finite-time Lyapunov exponent.

  14. Biventricular MR volumetric analysis and MR flow quantification in the ascending aorta and pulmonary trunk for quantification of valvular regurgitation; Biventrikulaere MR-Volumetrie und MR-Flussmessungen in Aorta ascendens und Truncus pulmonalis zur Quantifizierung von Klappeninsuffizienzen

    Energy Technology Data Exchange (ETDEWEB)

    Rominger, M.B. [Marburg Univ. (Germany). Abt. Strahlendiagnostik; Kluge, A.; Bachmann, G.F. [Diagnostische Radiologie, Kerckhoff-Klinik GmbH, Bad Nauheim (Germany)

    2004-03-01

    Purpose: To test the value of biventricular volumetric analysis and the combination of biventricular volumetric analysis with flow quantification in the ascending aorta (Ao) and pulmonary trunk (Pu) for quantification of regurgitation volume and cardiac function in valvular regurgitation (VR) according to location and presence of single or multivalvular disease. Materials and Methods: In 106 patients, the stroke volumes were assessed by measuring the biventricular volumes and the forward-stroke volumes in the great and small circulation by measuring the flow in the Ao and Pu. Valve regurgitation volumes and quotients were calculated for single and multivalvular disease and correlated with semiquantitative 2D-echocardiography (grade I-IV). For the assessment of the cardiac function in VR, the volumetric parameters of ejection fraction and end-diastolic (EDV) and end-systolic (ESV) volumes were determined. Results: The detection rate was 49% for left ventricular (LV) VR and 42% for right ventricular (RV) VR. Low LV VR and RV VR usually could not be detected quantitatively, with the detection rate improving with echocardiographically higher insufficiency grades. Quantitative MRI could detect a higher grade solitary aortic valve insufficiency ({>=}2) in 11 of 12 patients and higher grade mitral valve insufficiency in 4 of 10 patients. A significant increase in RV and LV ventricular EDV and ESV was seen more often with increased MR regurgitation volumes. Aortic stenosis did not interfere with flow measurements in the Ao. Conclusions: Biventricular volumetry combined with flow measurements in Ao and Pu is a robust, applicable and simple method to assess higher grade regurgitation volumes and the cardiac function in single and multivalvular regurgitation at different locations. It is an important application for the diagnosis of VR by MRI. [German] Ziel: Untersuchung der Wertigkeit der biventrikulaeren Volumetrie und der Kombination von biventrikulaerer Volumetrie und

  15. Exchange Flow Rate Measurement Technique in Density Different Gases

    Directory of Open Access Journals (Sweden)

    Motoo Fumizawa

    2012-04-01

    Full Text Available Buoyancy-driven exchange flows of helium-air through inclined a narrow tube was investigated. Exchange flows may occur following the opening of a window for ventilation, as well as when a pipe ruptures in a high temperature gas-cooled reactor. The experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. A high-speed camera recorded the flow behavior. The image of the flow was transferred to digital data, and the slow flow velocity, i.e. micro flow rate was measured by PIV software. Numerical simulation was carried out by the code of moving particle method with Lagrange method.

  16. Estimation of blood flow rates in large microvascular networks.

    Science.gov (United States)

    Fry, Brendan C; Lee, Jack; Smith, Nicolas P; Secomb, Timothy W

    2012-08-01

    Recent methods for imaging microvascular structures provide geometrical data on networks containing thousands of segments. Prediction of functional properties, such as solute transport, requires information on blood flow rates also, but experimental measurement of many individual flows is difficult. Here, a method is presented for estimating flow rates in a microvascular network based on incomplete information on the flows in the boundary segments that feed and drain the network. With incomplete boundary data, the equations governing blood flow form an underdetermined linear system. An algorithm was developed that uses independent information about the distribution of wall shear stresses and pressures in microvessels to resolve this indeterminacy, by minimizing the deviation of pressures and wall shear stresses from target values. The algorithm was tested using previously obtained experimental flow data from four microvascular networks in the rat mesentery. With two or three prescribed boundary conditions, predicted flows showed relatively small errors in most segments and fewer than 10% incorrect flow directions on average. The proposed method can be used to estimate flow rates in microvascular networks, based on incomplete boundary data, and provides a basis for deducing functional properties of microvessel networks. © 2012 John Wiley & Sons Ltd.

  17. Fluid/Vapor Separator for Variable Flow Rates

    Science.gov (United States)

    Lee, J. M.; Chuang, C.; Frederking, T. H.; Brown, G. S.; Kamioka, Y.; Vorreiter, J.

    1984-01-01

    Shutter varies gas throughput of porous plug. Variable area exposed on porous plug allows to pass varying rates of vapor flow while blocking flow of liquid helium II from cryogenic bath. Applications in refining operations, industrial chemistry, and steam-powered equipment.

  18. eaf tissue flows in ryegrass managed under different stocking rates

    Directory of Open Access Journals (Sweden)

    Mônique Foggiato da Silva

    2015-05-01

    Full Text Available Morphogenetic, structural variables and leaf biomass flows of Italian ryegrass (Lolium multiflorum Lam. were evaluated under two stocking rates: ‘Low’ and ‘High’. These rates were determined by heifers exclusively on pasture or on pasture and supplemented with corn grain. The experimental design was completely randomized following a repeated measure arrangement, two stocking rates, two and four replications of area for the stocking rates ‘low’ and ‘high’, respectively. The morphogenetic variables, the number of green leaves and tiller density were similar in both stocking rates. Leaf senescence rate was higher with low stocking rate. Heifers grazed with similar intensity and frequency in both stocking rates. The increase by 33.6% in the stocking rate caused by the use of supplement does not change the leaf biomass flow of Italian ryegrass, but alters its potential efficiency of use near the reproductive stage of the plant.

  19. variant formula for predicting peak expiratory flow rate in pregnant ...

    African Journals Online (AJOL)

    DR. AMINU

    Accepted: November, 2009. VARIANT FORMULA FOR PREDICTING PEAK EXPIRATORY FLOW RATE IN. PREGNANT WOMEN IN KURA LOCAL GOVERNMENT AREA, KANO STATE,. NIGERIA. A. I. Salisu. Department of Human Physiology, Faculty of Medicine, Bayero University, Kano salisahmedibrahim@yahoo.co.uk;.

  20. Design and Implementation of Automatic Air Flow Rate Control System

    Science.gov (United States)

    Akbar, A.; Saputra, C.; Munir, M. M.; Khairurrijal

    2016-08-01

    Venturimeter is an apparatus that can be used to measure the air flow rate. In this experiment we designed a venturimeter which equipped with a valve that is used to control the air flow rate. The difference of pressure between the cross sections was measured with the differential pressure sensor GA 100-015WD which can calculate the difference of pressures from 0 to 3737.33 Pa. A 42M048C Z36 stepper motor was used to control the valve. The precision of this motor rotation is about 0.15 °. A Graphical User Interface (GUI) was developed to monitor and set the value of flow rate then an 8-bit microcontroller was used to process the control system In this experiment- the venturimeter has been examined to get the optimal parameter of controller. The results show that the controller can set the stable output air flow rate.

  1. Maximizing the productivity of the microalgae Scenedesmus AMDD cultivated in a continuous photobioreactor using an online flow rate control.

    Science.gov (United States)

    McGinn, Patrick J; MacQuarrie, Scott P; Choi, Jerome; Tartakovsky, Boris

    2017-01-01

    In this study, production of the microalga Scenedesmus AMDD in a 300 L continuous flow photobioreactor was maximized using an online flow (dilution rate) control algorithm. To enable online control, biomass concentration was estimated in real time by measuring chlorophyll-related culture fluorescence. A simple microalgae growth model was developed and used to solve the optimization problem aimed at maximizing the photobioreactor productivity. When optimally controlled, Scenedesmus AMDD culture demonstrated an average volumetric biomass productivity of 0.11 g L-1 d-1 over a 25 day cultivation period, equivalent to a 70 % performance improvement compared to the same photobioreactor operated as a turbidostat. The proposed approach for optimizing photobioreactor flow can be adapted to a broad range of microalgae cultivation systems.

  2. Flow rates through intravenous access devices: an in vitro study.

    Science.gov (United States)

    Khoyratty, Saleem I; Gajendragadkar, Pushpaj R; Polisetty, Kiran; Ward, Sue; Skinner, Tim; Gajendragadkar, Parag R

    2016-06-01

    Fluid administration using intravenous (IV) access devices is required in many settings. There are a lack of quantitative data comparing traditional cannulas and modern access devices. We aimed to investigate flow rates through modern intravenous access devices using an in vitro system. This is an experimental study. Rates of flow of intravenous fluids (crystalloid and colloid) were measured through various access devices using a uroflowmeter. Standardized conditions and repeat measurements ensured validity. Fluid was administered with or without the addition of a pressure bag and needle-free valve. Increasing the size of cannulas improved flow. Fourteen-gauge cannulas had significantly higher mean flow rates compared to 14G central venous lines in all conditions (136% higher with no pressure bag/valve; 95% CI, +130% to +152%; P Flow rates in IV devices can be maximized by pressure bag use and removal of needle-free valves. The rapid infusion catheter and emergency infusion catheter allow some increase in flow over a 14G cannula. Familiarity with varying flow rates across IV access devices could better inform clinical decisions. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  3. Evaluation of IOM personal sampler at different flow rates.

    Science.gov (United States)

    Zhou, Yue; Cheng, Yung-Sung

    2010-02-01

    The Institute of Occupational Medicine (IOM) personal sampler is usually operated at a flow rate of 2.0 L/min, the rate at which it was designed and calibrated, for sampling the inhalable mass fraction of airborne particles in occupational environments. In an environment of low aerosol concentrations only small amounts of material are collected, and that may not be sufficient for analysis. Recently, a new sampling pump with a flow rate up to 15 L/min became available for personal samplers, with the potential of operating at higher flow rates. The flow rate of a Leland Legacy sampling pump, which operates at high flow rates, was evaluated and calibrated, and its maximum flow was found to be 10.6 L/min. IOM samplers were placed on a mannequin, and sampling was conducted in a large aerosol wind tunnel at wind speeds of 0.56 and 2.22 m/s. Monodisperse aerosols of oleic acid tagged with sodium fluorescein in the size range of 2 to 100 microm were used in the test. The IOM samplers were operated at flow rates of 2.0 and 10.6 L/min. Results showed that the IOM samplers mounted in the front of the mannequin had a higher sampling efficiency than those mounted at the side and back, regardless of the wind speed and flow rate. For the wind speed of 0.56 m/s, the direction-averaged (the average value of all orientations facing the wind direction) sampling efficiency of the samplers operated at 2.0 L/min was slightly higher than that of 10.6 L/min. For the wind speed of 2.22 m/s, the sampling efficiencies at both flow rates were similar for particles flow rates follows the inhalable mass curve for particles in the size range of 2 to 20 microm. The test results indicate that the IOM sampler can be used at higher flow rates.

  4. Blood flow rate measurements with indicator techniques revisited

    DEFF Research Database (Denmark)

    Sejrsen, Per; Bülow, Jens

    2009-01-01

    In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions......, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues....

  5. Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

    Science.gov (United States)

    Zhou, Xiaowei; Xia, Chunming; Stephen, Gandy; Khan, Faisel; Corner, George A; Hoskins, Peter R; Huang, Zhihong

    2017-05-01

    Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors. Copyright © 2017. Published by Elsevier Inc.

  6. Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation.

    Science.gov (United States)

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed; Pihl, Michael Johannes; Hansen, Kristoffer Lindskov; Stuart, Matthias Bo; Thomsen, Carsten; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

    2017-03-01

    Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames/s in a plane, and was used to estimate 3-D vector flow in a cross-sectional image plane. The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom ( ∅=8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow-rig compared with the expected 79.8 L/min, and to 2.68 ± 0.04 mL/stroke in the pulsating environment compared with the expected 2.57 ± 0.08 mL/stroke. Flow rates estimated in the common carotid artery of a healthy volunteer are compared with magnetic resonance imaging (MRI) measured flow rates using a 1-D through-plane velocity sequence. Mean flow rates were 333 ± 31 mL/min for the presented method and 346 ± 2 mL/min for the MRI measurements.

  7. Numerical study on flow rate limitation of open capillary channel flow through a wedge

    Directory of Open Access Journals (Sweden)

    Ting-Ting Zhang

    2016-04-01

    Full Text Available The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.

  8. Pricing and Unresponsive Flows Purging for Global Rate Enhancement

    Directory of Open Access Journals (Sweden)

    G. Abbas

    2010-01-01

    Full Text Available Pricing-based Active Queue Management (AQM, such as Random Exponential Marking (REM, outperforms other probabilistic counterpart techniques, like Random Early Detection (RED, in terms of both high utilization and negligible loss and delay. However, the pricing-based protocols do not take account of unresponsive flows that can significantly alter the subsequent rate allocation. This letter presents Purge (Pricing and Un-Responsive flows purging for Global rate Enhancement that extends the REM framework to regulate unresponsive flows. We show that Purge is effective at providing fairness and requires small memory and low-complexity operations.

  9. Variability of cutaneous lymphatic flow rates in melanoma patients.

    Science.gov (United States)

    Uren, R F; Howman-Giles, R B; Thompson, J F; Roberts, J; Bernard, E

    1998-06-01

    Preoperative lymphoscintigraphy was performed in 198 consecutive patients with cutaneous melanoma prior to their definitive surgical treatment. After intradermal injection of antimony sulphide colloid labelled with technetium-99m, lymphatic flow rates were measured in each patient and found to vary according to the location of the primary tumour. The fastest flow rates occurred from melanoma sites on the distal limbs, particularly the lower limbs. The slowest flow rates were from the head and neck region and the proximal limbs, especially the upper arms and shoulders. Lack of flow in the early dynamic images occurred most commonly for tumours on the upper arms and shoulders. These results can be used to optimize the timing of blue dye injection prior to surgery and may influence the sentinel node biopsy method to be used in individuals who show no early drainage.

  10. Does Ramadan fasting affect expiratory flow rates in healthy subjects?

    Science.gov (United States)

    Subhan, Mirza M F; Siddiqui, Qamar A; Khan, Mohammed N; Sabir, Salman

    2006-11-01

    To assess whether Ramadan fasting affects the expiratory flow rates in healthy subjects, and to know if these effects correlate to a change in other variables. This unmatched case-control longitudinal study includes 46 non-smoking healthy subjects who undertook lung function testing at the Aga Khan University, Pakistan. Expiratory flow rates and body mass were measured in 3 Islamic months, corresponding to November 2001 to January 2002. There was a significant reduction in body mass in Ramadan compared to pre and post Ramadan. No significant changes in expiratory flows were seen during Ramadan as compared to the pre Ramadan period. However, forced expiratory flow rates at 75% of vital capacity (FEF(75)) and between 75% and 85% of vital capacity (FEF(75-85)) showed a significant increase in the post Ramadan period compared to Ramadan. Changes in FEF(75) were negatively correlated to changes in body mass between Ramadan and post Ramadan. This study shows that Ramadan fasting will not affect expiratory flow rates in healthy subjects. Post Ramadan values did show an increase in FEF(75) and FEF(75-85), possibly due to changes in body water and fat content. The reductions in body mass were most probably due to lack of nutrition and not dehydration as the fasts were performed in winter. Collection of reference values or early phase clinical trials measuring expiratory flow rates should not be affected by Ramadan fasting.

  11. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    Directory of Open Access Journals (Sweden)

    M.A. Chowdhury

    2012-12-01

    Full Text Available Solid thin films have been deposited on stainless steel 202 (SS 202 substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in gas flow rate within the observed range. It is also found that deposition rate increases with the decrease in gap between activation heater and substrate. In addition, friction coefficient and wear rate of SS 202 sliding against SS 304 under different sliding velocities are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate is obtained after deposition than that of before deposition.

  12. Penetrometry and estimation of the flow rate of powder excipients.

    Science.gov (United States)

    Zatloukal, Z; Sklubalová, Z

    2007-03-01

    In this work, penetrometry with a sphere was employed to study the flow properties of non-consolidated pharmaceutical powder excipients: sodium chloride, sodium citrate, boric acid, and sorbitol. In order to estimate flow rate, the pressure of penetration in Pascals was used. Penetrometry measurement with a sphere requires modification of the measurement container, in particular by decreasing the diameter of the container, to prevent undesirable movement of material in a direction opposite to that in which the sphere penetrates. Thus penetrometry by a sphere seems to be similar to indentation by the Brinell hardness tester. The pressure of penetration was determined from the depth of penetration by analogy with the Brinell hardness number and an equation for the inter conversion of the two variables is presented. The penetration pressure allowed direct estimation of the flow rate only for those powder excipients with a size fraction in the range of 0.250-0.630 mm. Using the ratio of penetration pressure to bulk density, a polynomial quadratic equation was generated from which the flow rates for the group of all tested powders could be estimated. Finally, if the inverse ratio of bulk density and penetration pressure was used as an independent variable, the flow rate could be estimated by linear regression with the coefficient of determination r2 = 0.9941. In conclusion, using sphere penetrometry, the flow properties of non-consolidated powder samples could be investigated by indentation. As a result, a linear regression in which the flow rate was directly proportional to the powder bulk density and inversely proportional to the penetration pressure could be best recommended for the estimation of the flow rate of powder excipients.

  13. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse Rate Following Ingestion of Increased Coffee Concentrations in Healthy Male Adults. ... It further indicates that, mild doses of coffee confer benefits on airflow in the lungs. While higher doses are also beneficial in improving airflow in the airway, such doses ...

  14. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    We studied the effect of different concentrations of coffee on peak expiratory flow rate (PEFR), blood pressure and pulse rate in an attempt to determine some physiological effects of coffee intake. 18 apparently healthy adult males, age range 20 to 30 years, were recruited for the study over a three day period. Varying ...

  15. Influence of gain adjustment on 3-dimensional power Doppler indices and on spatiotemporal image correlation volumetric pulsatility indices using a flow phantom.

    Science.gov (United States)

    Miyague, Andre H; Raine-Fenning, Nicholas J; Pavan, Theo Z; Polanski, Lukasz T; Baumgarten, Miriam N; Nastri, Carolina O; Martins, Wellington P

    2013-10-01

    Spatiotemporal image correlation can be used to acquire 3-dimensional power Doppler information across a single cardiac cycle. Assessment and comparison of the systolic and diastolic components of the data sets allow measurement of the recently introduced "volumetric pulsatility index" (vPI) through algorithms comparable with those used in 2-dimensional Doppler waveform analysis. The vPI could potentially overcome the dependency on certain machine settings, such as power, color gain, pulse repetition frequency, and attenuation, since these factors would affect the power Doppler signal equally throughout the cardiac cycle. The objective of this study was to compare the effect of color gain on the vascularization index (VI), vascularization-flow index (VFI), and vPI using an in vitro flow phantom model. We separated gains into 3 bands: -8 to -1 (no noise), -1 to +5 (low noise), and +5 to +8 (obvious noise). The vPI was determined from the 3-dimensional VI or VFI using the formula vPI = (maximum - minimum)/mean. Using no-noise gains, we observed that although the VI and VFI increased linearly with gain, the vPI was substantially less dependent on this adjustment. The VI and VFI continued to increase linearly with gain, whereas the vPI decreased slightly using low-noise gains. When gain was increased above the lower limit of obvious noise (+5), the VI and VFI increased noticeably, and there were marked reductions in both vPI values. We conclude that the vPI is less affected by changes in color gain than the VI and VFI at no-noise gains.

  16. Melt volume flow rate and melt flow rate of kenaf fibre reinforced Floreon/magnesium hydroxide biocomposites.

    Science.gov (United States)

    Lee, C H; Sapuan, S M; Lee, J H; Hassan, M R

    2016-01-01

    A study of the melt volume flow rate (MVR) and the melt flow rate (MFR) of kenaf fibre (KF) reinforced Floreon (FLO) and magnesium hydroxide (MH) biocomposites under different temperatures (160-180 °C) and weight loadings (2.16, 5, 10 kg) is presented in this paper. FLO has the lowest values of MFR and MVR. The increment of the melt flow properties (MVR and MFR) has been found for KF or MH insertion due to the hydrolytic degradation of the polylactic acid in FLO. Deterioration of the entanglement density at high temperature, shear thinning and wall slip velocity were the possible causes for the higher melt flow properties. Increasing the KF loadings caused the higher melt flow properties while the higher MH contents created stronger bonding for higher macromolecular chain flow resistance, hence lower melt flow properties were recorded. However, the complicated melt flow behaviour of the KF reinforced FLO/MH biocomposites was found in this study. The high probability of KF-KF and KF-MH collisions was expected and there were more collisions for higher fibre and filler loading causing lower melt flow properties.

  17. Estimation of Saturation Flow Rates at Signalized Intersections

    Directory of Open Access Journals (Sweden)

    Chang-qiao Shao

    2012-01-01

    Full Text Available The saturation flow rate is a fundamental parameter to measure the intersection capacity and time the traffic signals. However, it is revealed that traditional methods which are mainly developed using the average value of observed queue discharge headways to estimate the saturation headway might lead to underestimate saturation flow rate. The goal of this paper is to study the stochastic nature of queue discharge headways and to develop a more accurate estimate method for saturation headway and saturation flow rate. Based on the surveyed data, the characteristics of queue discharge headways and the estimation method of saturated flow rate are studied. It is found that the average value of queue discharge headways is greater than the median value and that the skewness of the headways is positive. Normal distribution tests were conducted before and after a log transformation of the headways. The goodness-of-fit test showed that for some surveyed sites, the queue discharge headways can be fitted by the normal distribution and for other surveyed sites, the headways can be fitted by lognormal distribution. According to the queue discharge headway characteristics, the median value of queue discharge headways is suggested to estimate the saturation headway and a new method of estimation saturation flow rates is developed.

  18. A MEMS-Based Flow Rate and Flow Direction Sensing Platform with Integrated Temperature Compensation Scheme

    Directory of Open Access Journals (Sweden)

    Chia-Yen Lee

    2009-07-01

    Full Text Available This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD. In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5o error.

  19. Doppler-Based Flow Rate Sensing in Microfluidic Channels

    Directory of Open Access Journals (Sweden)

    Liron Stern

    2014-09-01

    Full Text Available We design, fabricate and experimentally demonstrate a novel generic method to detect flow rates and precise changes of flow velocity in microfluidic devices. Using our method we can measure flow rates of ~2 mm/s with a resolution of 0.08 mm/s. The operation principle is based on the Doppler shifting of light diffracted from a self-generated periodic array of bubbles within the channel and using self-heterodyne detection to analyze the diffracted light. As such, the device is appealing for variety of “lab on chip” bio-applications where a simple and accurate speed measurement is needed, e.g., for flow-cytometry and cell sorting.

  20. A novel concept of measuring mass flow rates using flow induced ...

    Indian Academy of Sciences (India)

    1555–1566. c Indian Academy of Sciences. A novel concept of measuring mass flow rates using flow induced stresses. P I JAGAD1,∗, B P PURANIK2 and A W DATE2. 1Department of Mechanical Engineering, Sinhgad College of Engineering,. Vadgaon (Bk), Pune 411 041, India. 2Department of Mechanical Engineering, ...

  1. Efficiencies of flat plate solar collectors at different flow rates

    DEFF Research Database (Denmark)

    Chen, Ziqian; Furbo, Simon; Perers, Bengt

    2012-01-01

    Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...

  2. Effects of contrast administration on cardiac MRI volumetric, flow and pulse wave velocity quantification using manual and software-based analysis.

    Science.gov (United States)

    Fathi, Amir; Weir-McCall, Jonathan R; Struthers, Allan D; Lipworth, Brian J; Houston, Graeme

    2018-01-19

    The aim of the current study was to determine the effects of gadolinium contrast agent on right (RV) and left ventricular (LV) volumetric, aortic flow and pulse wave velocity (PWV) quantification using manual, semi-automatic and fully automatic analysis techniques. 61 participants free from known cardiovascular disease were recruited. Cardiac MR was performed on a 3 T scanner. A balanced steady-state free precession stack was acquired of the ventricles with phase contrast imaging of the aorta performed pre- and post-administration of 10 ml 0.5 mmol ml -1 gadoterate meglumine. The images were analysed manually, and using a semi-automated and a fully automated technique. 54 completed the study. Gadolinium-based contrast administration significantly increase the signal-to-noise ratio (pre: 830 ± 398 vs post: 1028 ± 540, p = 0.003) with no significant change in contrast-to-noise ratio (pre: 583 ± 302 vs post: 559 ± 346, p = 0.54). On LV analysis, post-contrast analysis yielded significantly higher end systolic volume (54 ± 20 vs 57 ± 18 ml, p = 0.04), and lower ejection fraction (59 ± 9 vs 57 ± 8%, p = 0.023). On RV analysis, gadolinium contrast resulted in no significant differences. Similar results were seen using the semi-automated and fully-automated techniques but with a larger magnitude of difference. Conversely, using both manual and software analysis aortic flow and PWV quantification proved robust to the effects of contrast agent producing only small non-significant differences. Gadolinium contrast administration significantly alters LV endocardial contour detection with this effect amplified when using semi-automated analysis techniques. In comparison, RV and PWV analysis is robust to these effects. Advances in knowledge: Contrast administration alters LV quantification but not flow analysis. However, these differences are small.

  3. Taylor dispersion analysis in coiled capillaries at high flow rates.

    Science.gov (United States)

    Lewandrowska, Anna; Majcher, Aldona; Ochab-Marcinek, Anna; Tabaka, Marcin; Hołyst, Robert

    2013-04-16

    Taylor Dispersion Analysis (TDA) has been performed for analytes moving at high flow rates in long, coiled capillaries. A thin injection zone of the analyte is stretched by the flow and final distribution of concentration of the analyte at the end of the capillary has the gaussian shape. The high flow rates in coiled capillary generate vortices. They convectively mix the analyte across the capillary. This mixing reduces the width of the gaussian distribution several times in comparison to the width obtained in a straight capillary in standard TDA. We have determined an empirical, scaling equation for the width as a function of the flow rate, molecular diffusion coefficient of the analyte, viscosity of the carrier phase, internal radius of the cylindrical capillary, and external radius of the coiled capillary. This equation can be used for different sizes of capillaries in a wide range of parameters without an additional calibration procedure. Our experimental results of flow in the coiled capillary could not be explained by current models based on approximate solutions of the Navier-Stokes equation. We applied the technique to determine the diffusion coefficients of the following analytes: salts, drugs, single amino acids, peptides (from dipeptides to hexapeptides), and proteins.

  4. Ultrasonic Enrichment of Flowing Blood Cells in Capillars: Influence of the Flow Rate

    Science.gov (United States)

    Carreras, Pilar; Gonzalez, Itziar; Ahumada, Oscar

    Red blood cells subjected to standing waves collect at the pressure nodes during their flow motion. Blood is a non-newtonian fluid whose density and other properties are defined by its flow velocity. Their drift motion is governed by the radiation force together with hydrodynamic conditions. This work presents a study of the blood cell enrichment performed in a rectangular capillar at f=1 MHz as a function of their flow motion. The cells collect along the central axis of the capillary in very few seconds, with a clearance in other lateral areas. Optimal flow rates below 100uL/min were found in the experiments.

  5. Flow rate and flow equation of pharmaceutical free-flowable powder excipients.

    Science.gov (United States)

    Sklubalová, Zdenka; Zatloukal, Zdenek

    2013-02-01

    Basic aspect of powder handling is powder flow which depends on mechanical properties of the solid material. This experimental work presents the results of flowability testing of the free-flowable particle size fraction of 0.0250-0.0315 cm of five powder excipients. The single-point determination of the mass flow rate from a cylindrical, flat-bottomed hopper was primarily influenced by the diameter of a circular orifice. The significant effect of the orifice height was also noted. Increasing the orifice height, the flow under gravity is directed resulting in the sudden acceleration of the flow rate. The critical zone relates to the orifice diameter. The multi-point determination of flowability employed the actual parameters of the flow equation which allows the prediction of the mass flow rate. The precision of the prediction was the basic criterion in optimization of the orifice geometry. Based on the results, the orifice height of 1.6 cm can be recommended for the correction of faster powder flow. For the slower powder flow, an orifice height of 0.2 cm can be used alternatively. In conclusion, the information about the orifice height used should be referred to whenever test the powder flowability and compare the results.

  6. A model for reaction rates in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.; Evans, J. S.

    1984-01-01

    To account for the turbulent temperature and species-concentration fluctuations, a model is presented on the effects of chemical reaction rates in computer analyses of turbulent reacting flows. The model results in two parameters which multiply the terms in the reaction-rate equations. For these two parameters, graphs are presented as functions of the mean values and intensity of the turbulent fluctuations of the temperature and species concentrations. These graphs will facilitate incorporation of the model into existing computer programs which describe turbulent reacting flows. When the model was used in a two-dimensional parabolic-flow computer code to predict the behavior of an experimental, supersonic hydrogen jet burning in air, some improvement in agreement with the experimental data was obtained in the far field in the region near the jet centerline. Recommendations are included for further improvement of the model and for additional comparisons with experimental data.

  7. Peak Expiratory Flow Rate in Petroleum Depot Workers and Petrol ...

    African Journals Online (AJOL)

    Peak Expiratory Flow Rate (PEFR) values in litres per minute were determined in petrol depot loaders, petrol station attendants and in control subjects. The PEFR values were 315 ± 94, 386 + 91 and 529 + 94 litres/min. in depot workers, petrol attendants and control subjects respectively. The value in the control subjects ...

  8. High flow rate microsieve for bio medical applications

    NARCIS (Netherlands)

    van Rijn, C.J.M.; Nijdam, W.; Elwenspoek, Michael Curt

    1995-01-01

    A new composite filtration membrane having a thin filtration or sieving layer has been developed. This filtration membrane with a high pore density and a narrow pore size distribution on a macro porous support shows good separation behaviour and a high flow rate. Because of the construction method,

  9. Peak expiratory flow rate and respiratory symptoms following ...

    African Journals Online (AJOL)

    Peak expiratory flow rate (PEFR) of 350 rural women aged (20-70 years) in Edo State, Nigeria who actively used wood as a source of fuel for cooking was measured. The height, chest circumference, weight and blood pressure of the women were also measured. Respiratory symptoms of cough with sputum production, ...

  10. variations of peak expiratory flow rate with anthropometric

    African Journals Online (AJOL)

    admin

    Summary: PEFR was measured in 300 healthy adult male and female staff and students of the. University of Benin, Benin City, and the College of Education, Ekiadolor, near Benin. The variations of. Peak Expiratory Flow Rate (PEFR) with respect to height (ht), weight (wt) and chest circumference (cc) were determined in ...

  11. Assessment of salivary flow rate: biologic variation and measure error.

    NARCIS (Netherlands)

    Jongerius, P.H.; Limbeek, J. van; Rotteveel, J.J.

    2004-01-01

    OBJECTIVE: To investigate the applicability of the swab method in the measurement of salivary flow rate in multiple-handicap drooling children. To quantify the measurement error of the procedure and the biologic variation in the population. STUDY DESIGN: Cohort study. METHODS: In a repeated

  12. Variability of flow rate when collecting stimulated human parotid saliva

    NARCIS (Netherlands)

    Burlage, FR; Pijpe, J; Coppes, RP; Hemels, MEW; Meertens, H; Canrinus, A; Vissink, A

    2005-01-01

    The aim of this study was to estimate the accuracy and reproducibility of citric-acid-stimulated parotid saliva sampling. In healthy volunteers a strong correlation (r(2) = 0.79) between flow rates from the left and right parotid gland was observed. In patients with Sjogren's syndrome this

  13. 3D modeling and characterization of a calorimetric flow rate sensor for sweat rate sensing applications

    Science.gov (United States)

    Iftekhar, Ahmed Tashfin; Ho, Jenny Che-Ting; Mellinger, Axel; Kaya, Tolga

    2017-03-01

    Sweat-based physiological monitoring has been intensively explored in the last decade with the hopes of developing real-time hydration monitoring devices. Although the content of sweat (electrolytes, lactate, urea, etc.) provides significant information about the physiology, it is also very important to know the rate of sweat at the time of sweat content measurements because the sweat rate is known to alter the concentrations of sweat compounds. We developed a calorimetric based flow rate sensor using PolydimethylSiloxane that is suitable for sweat rate applications. Our simple approach on using temperature-based flow rate detection can easily be adapted to multiple sweat collection and analysis devices. Moreover, we have developed a 3D finite element analysis model of the device using COMSOL Multiphysics™ and verified the flow rate measurements. The experiment investigated flow rate values from 0.3 μl/min up to 2.1 ml/min, which covers the human sweat rate range (0.5 μl/min-10 μl/min). The 3D model simulations and analytical model calculations covered an even wider range in order to understand the main physical mechanisms of the device. With a verified 3D model, different environmental heat conditions could be further studied to shed light on the physiology of the sweat rate.

  14. Effect of gas flow rate on titanium sponge reaction

    Science.gov (United States)

    Wang, Zhiliang; Feng, Gaoping; Wang, Mingdong; Hong, Yanji

    2017-08-01

    This paper expounds the important application of titanium sponge adsorption in inert gas purification, the reaction mechanism of titanium with nitrogen and oxygen was introduced. Explored the relationship between the absorption capacity of sponge titanium on the active gas in air samples and the gas flow rate. The model of sponge titanium for flowing air absorption was established by data analysis. The designed experiment verified the relationship between the titanium processing capacity and the gas collecting device. Finally, the influence of the mass of the sponge titanium on the degassing capacity was studied through experiments.

  15. Gravity current model of the volumetric growth of volcanic clouds: remote assessment with satellite imagery and estimation of mass eruption rate

    Science.gov (United States)

    Pouget, S.; Bursik, M. I.; Sparks, R. S.; Hogg, A. J.; Johnson, C. G.; Singh, T.; Pavolonis, M. J.

    2013-12-01

    The eruption of Eyjafjallajökull, Iceland in April and May, 2010, brought to light the hazards of airborne volcanic ash and the importance of being able to estimate the concentration of ash with time. This can be done using Volcanic Ash Transport and Dispersion models (VATD). These models require Eruption Source Parameters (ESP) such as the mass eruption rate (MER), as input. MER can be estimated from volumetric flux assuming gravity current behavior of the atmospheric intrusion. We used a gravity current model for the umbrella cloud and downwind plume in which the predominantly horizontal spreading through the atmosphere is driven by buoyancy forces and wind drag. Ash is advected by these atmospheric motions and settles out relatively slowly under the action of gravity. Given the importance of knowing ESP for VATD, we explored the use of the gravity current model applied to satellite imagery, using the geometric characteristics of ash clouds. To test the gravity current model on the use of satellite imagery, we estimated ESP from five well-studied and well-characterized historical eruptions: Mount St. Helens, 1980; Pinatubo, 1991, Redoubt, 1990; Hekla, 2000 and Eyjafjallajökull, 2010. These tests show that the methodologies yield results comparable to currently accepted methodologies of ESP estimation. We then applied the methodology to umbrella clouds produced by the eruptions of Okmok, 12 July 2008, and Sarychev Peak, 12 June 2009, and to the downwind plume produced by the eruptions of Hekla, 2000; Kliuchevsko'i, 1 October 1994; Kasatochi 7-8 August 2008 and Bezymianny, 1 September 2012; none of which had previous estimates of MER.

  16. Good production rate forecast based on flow, reservoir analysis

    Energy Technology Data Exchange (ETDEWEB)

    El-Feky, S.A.

    1987-03-16

    Well bore flow efficiencies under expected modes of production operations, coupled with a detailed reservoir description, are necessary for an accurate evaluation of production rate forecast. A production rate forecast for an offshore water-drive oil reservoir in the Gulf of Suez has been prepared. The best overall completion that exhibits both the highest initial producing rates and the long term producing efficiencies was determined for different wells. Three different flow configurations were examined. The wells were classified according to their productivity indices into Group I, Group II, and Group III, having average productivity indices of 53, 18 and 6 b/d/psi, respectively. The study was based on the performance of the three well groups. The Orkiszewski correlation for vertical multiphase pressure gradient calculation program available from Garrett Computing Systems was used to calculate bottom hole flowing pressures at a wide range of oil and water production rates with and without gas lift. Analysis of the expected reservoir performance was essential in evaluating the production forecast. Based on the results of the evaluation, reservoir operations, including well completions, control of water production, and gas lift requirements, have been recommended.

  17. Exchange Rate Regime, Real Exchange Rate, Trade Flows and Foreign Direct Investments: The case of Morocco

    OpenAIRE

    Bouoiyour, Jamal; Rey, Serge

    2005-01-01

    We study the behavior of the Real Effective Exchange Rate (REER) of the dirham against the European currencies (Europe of the 15), over the period 1960-2000 (annual data). We measure the volatility using standard deviation, and the misalignments as the difference between the actual REER and the equilibrium REER (NATREX model). We show that a rise of the volatility of the dirham reduces the trade flows (exports and imports). The misalignments affect also the trade flows: an overvaluation leads...

  18. A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.

    Science.gov (United States)

    Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric

    2012-03-07

    We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.

  19. Innovative model-based flow rate optimization for vanadium redox flow batteries

    Science.gov (United States)

    König, S.; Suriyah, M. R.; Leibfried, T.

    2016-11-01

    In this paper, an innovative approach is presented to optimize the flow rate of a 6-kW vanadium redox flow battery with realistic stack dimensions. Efficiency is derived using a multi-physics battery model and a newly proposed instantaneous efficiency determination technique. An optimization algorithm is applied to identify optimal flow rates for operation points defined by state-of-charge (SoC) and current. The proposed method is evaluated against the conventional approach of applying Faraday's first law of electrolysis, scaled to the so-called flow factor. To make a fair comparison, the flow factor is also optimized by simulating cycles with different charging/discharging currents. It is shown through the obtained results that the efficiency is increased by up to 1.2% points; in addition, discharge capacity is also increased by up to 1.0 kWh or 5.4%. Detailed loss analysis is carried out for the cycles with maximum and minimum charging/discharging currents. It is shown that the proposed method minimizes the sum of losses caused by concentration over-potential, pumping and diffusion. Furthermore, for the deployed Nafion 115 membrane, it is observed that diffusion losses increase with stack SoC. Therefore, to decrease stack SoC and lower diffusion losses, a higher flow rate during charging than during discharging is reasonable.

  20. THE OPTIMIZATION OF FLOW RATES OF AN EXTRUDER

    Directory of Open Access Journals (Sweden)

    I.O. Popoola

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: The article addresses how the flow rates of an extruder can be optimized. It mentions the plastic recycling industry as an example, which is only one of many solid waste recycling industries. The literature on flow rates is reviewed to demonstrate a gap that the current study aims to fills, in the hope that it will stimulate further research in a fertile area.

    AFRIKAANSE OPSOMMING: Die artikel adresseer die vraagstuk van vloeitempo van ‘n ekstrusieproses. Dit handel met ‘n voorbeeld van ‘n plastiekherwinningsproses wat spruit uit soliede afvalverwerking. ‘n Literatuurstudie toon hoedat die navorsing verdere areas wat braak lê, aanspreek in die hoop dat verdere studie gestimuleer sal word.

  1. Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

    OpenAIRE

    Bieliński Henryk

    2016-01-01

    The current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the low...

  2. Low-Flow-Rate Dry-Powder Feeder

    Science.gov (United States)

    Ramsey, Keith E.

    1994-01-01

    Apparatus feeds small, precise flow of dry powder through laser beam of optical analyzer, measuring patterns of light created by forward scattering (Fraunhofer diffraction) of laser beam from powder particles. From measurement, statistical distribution of sizes of powder particles computed. Developed for analyzing particle-size distributions of solid-propellant powders. Also adapted to use in pharmaceutical industry, in manufacture of metal powder, and in other applications in which particle-size distributions of materials used to control rates of chemical reactions and/or physical characteristics of processes.

  3. Remote Quantification of Smokestack Total Effluent Mass Flow Rates Using Imaging Fourier-Transform Spectroscopy

    Science.gov (United States)

    2011-03-01

    total effluent mass flow rates by combining spectrally-determined species concentrations with flow rates estimated via analysis of sequential images...of the flow velocity. Final effluent mass flow rates for CO2 and SO2 of 13.5 +- 3.78 kg/s and 71.3 +- 19.3 g/s were in good agreement with in situ

  4. Anomalous accumulation rates resulting from ice flow over Lake Vostok

    Science.gov (United States)

    Leonard, K. C.; Studinger, M.; Bell, R. E.; Tremblay, B.

    2004-12-01

    The accumulation rate of snow is crucial to the development of accurate age-depth models for ice-cores. The dating of the Vostok ice-core generally assumes that accumulation rates vary linearly between the core site and the ice divide 250 km to the west [Jouzel et al., 1996; Lorius et al., 1985; Petit et al., 1999], an assumption which impacts the timing of prominent climatic transitions. We present evidence for a local accumulation rate anomaly at the ice surface above the western shoreline of Lake Vostok. A significant thickening between isochronous layers results from this geographically fixed high accumulation zone which can be stratigraphically traced to a depth of 820-1100 m in the Vostok ice-core, a portion known for its high accumulation rates and paleoclimate records that deviate from other Antarctic ice-core records. This non-climatic accumulation anomaly in the Vostok ice-core impacts the flow dependent age models and subsequent interpretations of sequencing of global climate shifts during the last glacial. These previously unreported geographically fixed accumulation rate anomalies are introduced into ice-cores drilled away from ice domes (i.e., Byrd and Vostok) and should be considered in age depth models.

  5. Adiabatic flow curves of metallic materials at high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    El-Magd, E. [Technische Hochschule Aachen (Germany); Scholles, H. [Rheinmetall Industrie GmbH, Unterluess (Germany); Weisshaupt, H. [Rheinmetall Industrie GmbH, Unterluess (Germany)

    1996-08-01

    Dynamic compression tests are carried out on Armco iron, Cr-V-steel, Ni-Cr-Mo-V-steel, an austenitic Ni-Cr-Mo-steel, tantalum, nickel and Ni{sub 3}Al and magnesium. The flow curves are analysed to determine the influence of the deformation energy which is transformed into heat on the flow behaviour and mechanical stability. Not only the material properties but also the conditions of friction between the specimen and the compresion tool are found to have a greate influence on the flow stress reduction and stability. High frictional forces promote mechanical instability of materials with low strain hardening and low strain rate sensitivity. (orig.) [Deutsch] Schlagdruckversuche werden an Armcoeisen, CrV-Stahl, NiCr-MoV-Stahl, austenitischen NiCrMo-Stahl, Tantal, Nickel, Ni{sub 3}Al und Magnesium durchgefuehrt. Die ermittelten Fliesskurven werden analysiert, um den Einfluss der in Waerme umgewandelte Verformungsarbeit auf das Fliessverhalten und die mechanische Stabilitaet zu erfassen. Nicht nur die Werkstoffeigenschaften sondern auch die Reibungsbedingungen erweisen sich als massgebliche Einflussgroessen fuer Fliessspannungsabnahme und die Stabilitaet. Hohe Reibungskraefte foerdern die Verformungslokalisierung und die mechanische Instabilitaet von Werkstoffen mit niedriger Verfestigung und niedriger Geschwindigkeitsempfindlichkeit. (orig.)

  6. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    Hydrologic turnover of the hyporheic zone (HZ) is the process of HZ flowpaths receiving water and solutes from the stream channel while simultaneously contributing water and solutes from the HZ back to the stream channel. The influence of hydrologic turnover on HZ solute storage depends on the relative magnitude of hyporheic exchange rates (i.e. physical transport) and biogeochemical reaction rates. Because both exchange rates and reaction rates are unsteady in natural systems, the availability of solutes in the HZ is controlled by the legacy of hydraulic and biological conditions. In this study, we quantify the influence of unsteady flows on hydrologic turnover of the HZ. We study a glacial melt stream in the McMurdo Dry Valleys of Antarctica (MDVs). The MDVs provide an ideal setting for investigating hydrologic and chemical storage characteristics of HZs, because nearly all streamflow is generated from glacier melt and the HZ is vertically bounded by continuous permafrost. A dense network of shallow groundwater wells and piezometers was installed along a 60-meter reach of Von Guerard Stream. 12 days of continuous water level data in each well was used to compute the magnitude and direction of 2D hydraulic gradients between the stream channel and lateral hyporheic aquifer. Piezometers were sampled daily for stable isotope abundances. The direction and magnitude of the cross-valley (CV), perpendicular to the thalweg, component of hydraulic gradients is sensitive to daily flood events and exhibits significant spatial heterogeneity. CV gradients are consistently oriented from the hyporheic aquifer towards the stream channel on 2 sections of the study reach, whereas CV gradients are consistently oriented from the stream channel towards the hyporheic aquifer on 1 section. Three sections show diel changes in orientation of CV gradients, coincident with the passage of daily flood events. During a 4-day period of low flows, the HZ is isotopically distinct from the stream

  7. High flow rates during modified ultrafiltration decrease cerebral blood flow velocity and venous oxygen saturation in infants.

    Science.gov (United States)

    Rodriguez, Rosendo A; Ruel, Marc; Broecker, Lothar; Cornel, Garry

    2005-07-01

    The intracranial hemodynamic effects of modified ultrafiltration in children are unknown. We investigated the effects of different blood flow rates during modified ultrafiltration on the cerebral hemodynamics of children with weights above and below 10 kg. Thirty-one children (weights: 10 kg, n = 10) undergoing cardiopulmonary bypass were studied. Middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations were measured before, five minutes from the beginning, and at the end of ultrafiltration. Patients were classified according to their blood flow rates during ultrafiltration in three groups: high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rates (flow rates of ultrafiltration and the decline in mean cerebral blood flow velocity (r = - 0.48; p = 0.005) and cerebral oxygen saturation (r = - 0.49; p = 0.005) or hematocrit increase (r = 0.59; p = 0.001). Infants exposed to high flow rates had greater reduction of cerebral blood flow velocity and regional mixed venous saturation and higher hematocrit at the end of ultrafiltration compared with those subjected to moderate and low flow rates (p flow rates through the ultrafilter during modified ultrafiltration transiently decrease the cerebral circulation in young infants compared with lower blood flow rates. These effects may be related to an increased diastolic runoff from the aorta into the ultrafiltration circuit that leads to a "stealing" effect from the intracranial circulation, which may be important in infants with dysfunctional cerebral autoregulation.

  8. The Piece Wise Linear Reactive Flow Rate Model

    Science.gov (United States)

    Vitello, Peter; Souers, P. Clark

    2006-07-01

    For non-ideal explosives a wide range of behavior is observed in experiments dealing with differing sizes and geometries. A predictive detonation model must be able to reproduce many phenomena including such effects as: variations in the detonation velocity with the radial diameter of rate sticks; slowing of the detonation velocity around gentle corners; production of dead zones for abrupt corner turning; failure of small diameter rate sticks; and failure for rate sticks with sufficiently wide cracks. Most models have been developed to explain one effect at a time. Often, changes are made in the input parameters used to fit each succeeding case with the implication that this is sufficient for the model to be valid over differing regimes. We feel that it is important to develop a model that is able to fit experiments with one set of parameters. To address this we are creating a new generation of models that are able to produce better fitting to individual data sets than prior models and to simultaneous fit distinctly different regimes of experiments. Presented here are details of our new Piece Wise Linear reactive flow model applied to LX-17.

  9. Effect of Flow Characteristics in the Downstream of Butterfly Valve on the Flow Rate Measurement using Venturi Tube

    Science.gov (United States)

    Yoon, Seok Ho; Lee, Jungho; Yu, Cheong Hwan; Park, San-Jin; Chung, Chang-Hwan

    2010-06-01

    For testing large-capacity pump, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, butterfly-type valve is generally used due to its compactness. However, butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using venturi tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. PIV system is used to visualize and analyze flow in the downstream region of butterfly valve. According to valve opening angle, the flow characteristics and the accuracy of flow rate measurement are investigated.

  10. Copepod feeding currents : flow patterns, filtration rates and energetics

    NARCIS (Netherlands)

    van Duren, L.A; Stamhuis, E.J; Videler, J.J

    Particle image velocimetry was used to construct a quasi 3-dimensional image of the flow generated by the feeding appendages of the calanoid copepod Temora longicornis. By scanning layers of flow, detailed information was obtained on flow velocity and velocity gradients. The flow around feeding T.

  11. Design and construction of a novel Coriolis mass flow rate meter

    NARCIS (Netherlands)

    Mehendale, A.; Zwikker, Rini; Jouwsma, Wybren

    2009-01-01

    The Coriolis principle for measuring flow rates has great advantages compared to other flow measurement principles, the most important being that mass flow is measured directly. Up to now the measurement of low flow rates posed a great challenge. In a joint research project, the University of Twente

  12. Solid Hydrogen Particles and Flow Rates Analyzed for Atomic Fuels

    Science.gov (United States)

    Palaszewski, Bryan A.

    2003-01-01

    The experiments were conducted at Glenn's Small Multipurpose Research Facility (SMIRF, ref. 5). The experimental setup was placed in the facility's vacuum tank to prevent heat leaks and subsequent boiloff of the liquid helium. Supporting systems maintained the temperature and pressure of the liquid helium bath where the solid particles were created. Solid hydrogen particle formation was tested from February 23 to April 2, 2001. Millimeter-sized solid-hydrogen particles were formed in a Dewar of liquid helium as a prelude to creating atomic fuels and propellants for aerospace vehicles. Atomic fuels or propellants are created when atomic boron, carbon, or hydrogen is stored in solid hydrogen particles. The current testing characterized the solid hydrogen particles without the atomic species, as a first step to creating a feed system for the atomic fuels and propellants. This testing did not create atomic species, but only sought to understand the solid hydrogen particle formation and behavior in the liquid helium. In these tests, video images of the solid particle formation were recorded, and the total mass flow rate of the hydrogen was measured. The mass of hydrogen that went into the gaseous phase was also recorded using a commercially available residual gas analyzer. The temperatures, pressures, and flow rates of the liquids and gases in the test apparatus were recorded as well. Testing conducted in 1999 recorded particles as small as 2 to 5 mm in diameter. The current testing extended the testing conditions to a very cold Dewar ullage gas of about 20 to 90 K above the 4 K liquid helium. With the very cold Dewar gas, the hydrogen freezing process took on new dimensions, in some cases creating particles so small that they seemed to be microscopic, appearing as infinitesimally small scintillations on the videotaped images.

  13. The influence of urinary flow rate on mercury excretion in children.

    Science.gov (United States)

    Trachtenberg, Felicia; Barregård, Lars; McKinlay, Sonja

    2010-01-01

    There is limited literature concerning the effect of urinary flow rate on mercury excretion at low-level exposure. The aim of the present study is to examine the influence of urinary flow rate on mercury excretion in children. Also of interest is the influence of flow rate on creatinine excretion and creatinine-corrected mercury, which arisearises with spot urine samples. A substudy of the New England Children's Amalgam Trial collected pairs of urine samples from children aged 10-16 years: a timed overnight collection and a spot daytime sample collected the following day. These samples were analyzed for mercury and creatinine concentration. Regression analysis was used to model the effect of urinary flow rate in the timed overnight samples. A paired t-test compared concentrations and creatinine-corrected mercury between overnight and daytime samples. Creatinine excretion rate (mg/h) increased significantly with urinary flow rate (mL/h), whereas creatinine concentration (g/L) decreased with flow rate. We found a non-significant increase in mercury excretion rate (ng/h) with flow rate, and mercury concentration decreased with flow rate. Mercury and creatinine concentrations were significantly higher in the overnight compared to daytime samples. For creatinine-corrected mercury, no significant impact of urinary flow rate was found. Although the creatinine excretion rate, and probably the mercury excretion rate, increased with urinary flow rate, the mercury/creatinine ratio seemed relatively unaffected by urinary flow rate. Copyright 2009 Elsevier GmbH. All rights reserved.

  14. Analysis of flow decay potential on Galileo. [oxidizer flow rate reduction by iron nitrate precipitates

    Science.gov (United States)

    Cole, T. W.; Frisbee, R. H.; Yavrouian, A. H.

    1987-01-01

    The risks posed to the NASA's Galileo spacecraft by the oxidizer flow decay during its extended mission to Jupiter is discussed. The Galileo spacecraft will use nitrogen tetroxide (NTO)/monomethyl hydrazine bipropellant system with one large engine thrust-rated at a nominal 400 N, and 12 smaller engines each thrust-rated at a nominal 10 N. These smaller thrusters, because of their small valve inlet filters and small injector ports, are especially vulnerable to clogging by iron nitrate precipitates formed by NTO-wetted stainless steel components. To quantify the corrosion rates and solubility levels which will be seen during the Galileo mission, corrosion and solubility testing experiments were performed with simulated Galileo materials, propellants, and environments. The results show the potential benefits of propellant sieving in terms of iron and water impurity reduction.

  15. Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    B. Zahed

    2013-01-01

    Full Text Available The growth rate and uniformity of Carbon Nano Tubes (CNTs based on Chemical Vapor Deposition (CVD technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as carbon source and mixture of argon and hydrogen as  carrier gas enters into a horizontal CVD reactor at atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.

  16. GROWTH RATE DISPERSION (GRD OF THE (010 FACE OF BORAX CRYSTALS IN FLOWING SOLUTION

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax crystals from aqueous solutions in the (010 direction at various flow rates were measured. The observed variations of the growth rate can be represented by a normal distribution.  It was found that there is no correlation between growth rate distribution and solution flow under these experimental conditions.   Keywords: Growth rate dispersion (GRD, borax, flow rate

  17. Investigations for effect of Al2O3–H2O nanofluid flow rate on the efficiency of direct absorption solar collector

    Directory of Open Access Journals (Sweden)

    Hemant Kumar Gupta

    2015-03-01

    Full Text Available The efficiency of conventional tube‐ in plate type solar collectors is limited due to higher heat losses for surface based solar energy absorption and indirect transfer of heat from hot absorber surface to working fluid having poor heat transfer properties flowing through tubes. In this paper, a prototype direct absorption solar collector having gross area 1.4 m2 working on volumetric absorption principle is developed to investigate the effect of using Al2O3–H2O nanofluid as heat transfer fluid at different flow rates. Experimentation was carried using distilled water and 0.005% volume fractions of 20 nm size Al2O3 nanoparticles at three flow rates of 1.5, 2 and 2.5 lpm. ASHRAE standard 93-86 was followed for calculation of instantaneous efficiency of solar collector. Use of nanofluid improves the optical and thermo physical properties that result into an increase in the efficiency of the collector in all cases of using nanofluids in place of water. Collector efficiency enhancement of 8.1% and 4.2% has been observed for 1.5 and 2 lpm flow rate of nanofluid respectively. Optimum flow rate of 2.5 and 2 lpm towards maximum collector efficiency have also been observed for water and nanofluid respectively.

  18. Dependence of Selected Water Quality Parameters on Flow Rates in River Profiles in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Eduard Hanslík

    2016-06-01

    The results show that in the monitored profiles, there is a direct relationship with flow rate in case of N-NO3-, suspended solids and O2. Temperature shows an inverse relationship with the flow rate. Other parameters show different relationship with the flow rate in individual monitored profiles or do not show statistically significant relation.

  19. Volumetric composition of nanocomposites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Mannila, Juha

    2015-01-01

    Detailed characterisation of the properties of composite materials with nanoscale fibres is central for the further progress in optimization of their manufacturing and properties. In the present study, a methodology for the determination and analysis of the volumetric composition of nanocomposites...... significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials. The known gravimetric composition of the nanocomposites is converted into a volumetric composition....... An analytical model, previously established for conventional fibre composites, is used for the analysis of the volumetric composition. For the aluminosilicate/polylactate nanocomposites, based on the established linear relationship between the porosity content and the fibre volume content, the fibre correlated...

  20. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas

    2015-01-01

    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect......L/min diastolic BP, mean arterial pressure, PR and CO remained unchanged. CONCLUSION: Our study does not show any consistent trend in BP changes by a reduction in EBFR. Reduction in EBFR if BP falls during IDH is thus not supported. However, none of the patients experienced IDH. Further studies are required...... to evaluate the impact of changes in EBFR on BP during IDH....

  1. Solenoidal filtering of volumetric velocity measurements using Gaussian process regression

    NARCIS (Netherlands)

    Azijli, I.; Dwight, R.P.

    2015-01-01

    Volumetric velocity measurements of incompressible flows contain spurious divergence due to measurement noise, despite mass conservation dictating that the velocity field must be divergence-free (solenoidal). We investigate the use of Gaussian process regression to filter spurious divergence,

  2. Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

    Science.gov (United States)

    Fang, Min; Xu, Ke-Jun; Zhu, Wen-Jiao; Shen, Zi-Wen

    2016-01-01

    Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

  3. Ventilator gas flow rates affect inspiratory time and ventilator efficiency index in term lambs.

    Science.gov (United States)

    Bach, Katinka P; Kuschel, Carl A; Oliver, Mark H; Bloomfield, Frank H

    2009-01-01

    Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high gas flow rates. We hypothesised that altering bias gas flow rates would change the efficiency of ventilation and thereby affect ventilatory parameters. We tested this hypothesis using an artificial lung followed by ventilation of 8 term lambs. Between flows of 2 and 15 l/min, inflation time (Ti) in the artificial lung was inversely related to the bias gas flow rate. In the ventilated lambs, Ti was inversely related to flow rates up to 10 l/min, with no statistically significant effect at flow rates >10 l/min. There were no adverse effects on gas exchange or cardiovascular parameters until a flow rate of 3 l/min was used, when inadequate gas exchange occurred. Ti is inversely associated with the bias gas flow rate. Flow rates much lower than those used in many neonatal units seem to provide adequate ventilation. We suggest that the role of ventilator gas flow rates, which may potentially influence shear stress in ventilator-induced lung injury, merits further investigation. Copyright 2009 S. Karger AG, Basel.

  4. A COMPREHENSIVE STUDY OF HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS.

    Science.gov (United States)

    FOGARTY, WILLIAM J.; REEDER, MILTON E.

    A DETERMINATION OF THE HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS WAS MADE TO IDENTIFY THE FLOW CHARACTERISTICS AND TO PROVIDE A MORE PRECISE BASIS FOR THE ESTABLISHMENT OF DESIGN CRITERIA FOR SEWAGE DISPOSAL FACILITIES IN SCHOOLS. WATER FLOW DATA WAS COLLECTED FOR 158 SCHOOLS AND SEWAGE FLOW DATA FROM 42 SCHOOLS. THE FINDINGS…

  5. Unstimulated salivary flow rate, pH and buffer capacity of saliva in healthy volunteers.

    Science.gov (United States)

    Fenoll-Palomares, C; Muñoz Montagud, J V; Sanchiz, V; Herreros, B; Hernández, V; Mínguez, M; Benages, A

    2004-11-01

    To assess the salivary flow rate, pH, and buffer capacity of healthy volunteers, and their relationships with age, gender, obesity, smoking, and alcohol consumption, and to establish the lower-end value of normal salivary flow (oligosialia). A prospective study was conducted in 159 healthy volunteers (age > 18 years, absence of medical conditions that could decrease salivary flow). Unstimulated whole saliva was collected during ten minutes, and salivary flow rate (ml/min), pH, and bicarbonate concentration (mmol/l) were measured using a Radiometer ABL 520. The 5 percentile of salivary flow rate and bicarbonate concentration was considered the lower limit of normality. Median salivary flow rate was 0.48 ml/min (range: 0.1-2 ml/min). Age younger than 44 years was associated with higher flow rates (OR 2.10). Compared with women, men presented a higher flow rate (OR 3.19) and buffer capacity (OR 2.81). Bicarbonate concentration correlated with salivary flow rate. The lower-end values of normal flow rate and bicarbonate concentration were 0.15 ml/min and 1.800 mmol/l, respectively. The presence of obesity, smoking, and alcohol consumption did not influence salivary parameters. In healthy volunteers, salivary flow rate depends on age and gender, and correlates with buffer capacity. Obesity, smoking, and alcohol use do not influence salivary secretion.

  6. Energy savings and higher volumetric loading rate achieved in the conventional anoxic-oxic process for sewage treatment by enhancing biomass retention in the secondary clarifier.

    Science.gov (United States)

    Zhang, Xueyu; Liu, Fengyuan; Zheng, Shaokui

    2017-06-01

    This is the first study to achieve a short HRT (∼2h for the A/O reactor), high MLSS (∼10gL(-1)), and high volumetric loading (∼3.7kg CODm(-3)d(-1) and ∼0.6kg NH4-Nm(-3)d(-1)) in the A/O process for sewage treatment by enhancing biomass retention in the secondary clarifier (∼4h settling time), which we refer to as the high-performance A/O process (HP-A/O) in this paper. Over 258days of continuous operation, with a decrease in HRT from 12 to 2h, remarkable COD (95±3%), NH4(+)-N (98±2%), TN (79±5%), and TP (74±10%) removals were stably achieved, while the air requirement significantly decreased by 22%. The HP-A/O process offers advantages over the conventional A/O process (6-8h for A/O reactor, 3-5gL(-1)MLSS, and ∼1.0kg CODm(-3)d(-1)) for sewage treatment in terms of its lower energy consumption, smaller footprint and reactor requirements. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Measurement of retinal blood flow rate in diabetic rats: disparity between techniques due to redistribution of flow.

    Science.gov (United States)

    Leskova, Wendy; Watts, Megan N; Carter, Patsy R; Eshaq, Randa S; Harris, Norman R

    2013-04-26

    Reports of altered retinal blood flow in experimental models of type I diabetes have provided contrasting results, which leads to some confusion as to whether flow is increased or decreased. The purpose of our study was to evaluate early diabetes-induced changes in retinal blood flow in diabetic rats, using two distinctly different methods. Diabetes was induced by injection of streptozotocin (STZ), and retinal blood flow rate was measured under anesthesia by a microsphere infusion technique, or by an index of flow based on the mean circulation time between arterioles and venules. Measurements in STZ rats were compared to age-matched nondiabetic controls. In addition, the retinal distribution of fluorescently-labeled red blood cells (RBCs) was viewed by confocal microscopy in excised flat mounts. Retinal blood flow rate was found to decrease by approximately 33% in the STZ rats compared to controls (P contrast, the mean circulation time through the retina was found to be almost 3× faster in the STZ rats (P < 0.01). This contradiction could be explained by flow redistribution through the superficial vessels of the diabetic retina, with this possibility supported by our observation of significantly fewer RBCs flowing through the deeper capillaries. We conclude that retinal blood flow rate is reduced significantly in the diabetic rat, with a substantial decrease of flow through the capillaries due to shunting of blood through the superficial layer, allowing rapid transit from arterioles to venules.

  8. Study on solid-liquid two-phase unsteady flow characteristics with different flow rates in screw centrifugal pump

    Science.gov (United States)

    Li, R. N.; Y Wang, H.; Han, W.; Ma, W.; Shen, Z. J.

    2013-12-01

    The screw centrifugal pump is used as an object, and the unsteady numerical simulation of solid-liquid two-phase flow is carried out under different flow rate conditions in one circle by choosing the two-phase flow of sand and water as medium, using the software FLUENT based on the URANS equations, combining with sliding mesh method, and choosing the Mixture multiphase flow model and the SIMPLE algorithm. The results show that, with the flow rate increasing, the change trends for the pressure on volute outlet are almost constant, the fluctuation trends of the impeller axial force have a little change, the pressure and the axial force turn to decrease on the whole, the radial force gradually increases when the impeller maximum radius passes by half a cycle near the volute outlet, and the radial force gradually decreases when the maximum radius passes by the other half a cycle in a rotation cycle. The distributions of the solid particles are very uneven under a small flow rate condition on the face. The solid particles under a big flow rate condition are distributed more evenly than the ones under a small flow rate condition on the back. The theoretical basis and reference are provided for improving its working performance.

  9. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates.

    Science.gov (United States)

    Mauri, Tommaso; Alban, Laura; Turrini, Cecilia; Cambiaghi, Barbara; Carlesso, Eleonora; Taccone, Paolo; Bottino, Nicola; Lissoni, Alfredo; Spadaro, Savino; Volta, Carlo Alberto; Gattinoni, Luciano; Pesenti, Antonio; Grasselli, Giacomo

    2017-10-01

    Limited data exist on the correlation between higher flow rates of high-flow nasal cannula (HFNC) and its physiologic effects in patients with acute hypoxemic respiratory failure (AHRF). We assessed the effects of HFNC delivered at increasing flow rate on inspiratory effort, work of breathing, minute ventilation, lung volumes, dynamic compliance and oxygenation in AHRF patients. A prospective randomized cross-over study was performed in non-intubated patients with patients AHRF and a PaO2/FiO2 (arterial partial pressure of oxygen/fraction of inspired oxygen) ratio of ≤300 mmHg. A standard non-occlusive facial mask and HFNC at different flow rates (30, 45 and 60 l/min) were randomly applied, while maintaining constant FiO2 (20 min/step). At the end of each phase, we measured arterial blood gases, inspiratory effort, based on swings in esophageal pressure (ΔPes) and on the esophageal pressure-time product (PTPPes), and lung volume, by electrical impedance tomography. Seventeen patients with AHRF were enrolled in the study. At increasing flow rate, HFNC reduced ΔPes (p flow rate also progressively reduced minute ventilation (p flow rates was better described by exponential fitting, while ΔEELV, V T/ΔPes and oxygenation improved linearly. In this cohort of patients with AHRF, an increasing HFNC flow rate progressively decreased inspiratory effort and improved lung aeration, dynamic compliance and oxygenation. Most of the effect on inspiratory workload and CO2 clearance was already obtained at the lowest flow rate.

  10. Nonequilibrium volumetric response of shocked polymers

    Energy Technology Data Exchange (ETDEWEB)

    Clements, B E [Los Alamos National Laboratory

    2009-01-01

    Polymers are well known for their non-equilibrium deviatoric behavior. However, investigations involving both high rate shock experiments and equilibrium measured thermodynamic quantities remind us that the volumetric behavior also exhibits a non-equilibrium response. Experiments supporting the notion of a non-equilibrium volumetric behavior will be summarized. Following that discussion, a continuum-level theory is proposed that will account for both the equilibrium and non-equilibrium response. Upon finding agreement with experiment, the theory is used to study the relaxation of a shocked polymer back towards its shocked equilibrium state.

  11. Gas phase dispersion in compost as a function of different water contents and air flow rates

    Science.gov (United States)

    Sharma, Prabhakar; Poulsen, Tjalfe G.

    2009-07-01

    Gas phase dispersion in a natural porous medium (yard waste compost) was investigated as a function of gas flow velocity and compost volumetric water content using oxygen and nitrogen as tracer gases. The compost was chosen because it has a very wide water content range and because it represents a wide range of porous media, including soils and biofilter media. Column breakthrough curves for oxygen and nitrogen were measured at relatively low pore gas velocities, corresponding to those observed in for instance soil vapor extraction systems or biofilters for air cleaning at biogas plants or composting facilities. Total gas mechanical dispersion-molecular diffusion coefficients were fitted from the breakthrough curves using a one-dimensional numerical solution to the advection-dispersion equation and used to determine gas dispersivities at different volumetric gas contents. The results showed that gas mechanical dispersion dominated over molecular diffusion with mechanical dispersion for all water contents and pore gas velocities investigated. Importance of mechanical dispersion increased with increasing pore gas velocity and compost water content. The results further showed that gas dispersivity was relatively constant at high values of compost gas-filled porosity but increased with decreasing gas-filled porosity at lower values of gas-filled porosity. Results finally showed that measurement uncertainty in gas dispersivity is generally highest at low values of pore gas velocity.

  12. Measuring Flow Rate in Crystalline Bedrock Wells Using the Dissolved Oxygen Alteration Method.

    Science.gov (United States)

    Vitale, Sarah A; Robbins, Gary A

    2017-07-01

    Determination of vertical flow rates in a fractured bedrock well can aid in planning and implementing hydraulic tests, water quality sampling, and improving interpretations of water quality data. Although flowmeters are highly accurate in flow rate measurement, the high cost and logistics may be limiting. In this study the dissolved oxygen alteration method (DOAM) is expanded upon as a low-cost alternative to determine vertical flow rates in crystalline bedrock wells. The method entails altering the dissolved oxygen content in the wellbore through bubbler aeration, and monitoring the vertical advective movement of the dissolved oxygen over time. Measurements were taken for upward and downward flows, and under ambient and pumping conditions. Vertical flow rates from 0.06 to 2.30 Lpm were measured. To validate the method, flow rates determined with the DOAM were compared to pump discharge rates and found to be in agreement within 2.5%. © 2017, National Ground Water Association.

  13. High Sensitivity Carbon Nanotubes Flow-Rate Sensors and Their Performance Improvement by Coating

    Directory of Open Access Journals (Sweden)

    Xing Yang

    2010-05-01

    Full Text Available A new type of hot-wire flow-rate sensor (HWFS with a sensing element made of a macro-sized carbon nanotube (CNT strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate.

  14. High Sensitivity Carbon Nanotubes Flow-Rate Sensors and Their Performance Improvement by Coating

    Science.gov (United States)

    Yang, Xing; Zhou, Zhaoying; Wang, Dingqu; Liu, Xiaoli

    2010-01-01

    A new type of hot-wire flow-rate sensor (HWFS) with a sensing element made of a macro-sized carbon nanotube (CNT) strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt) HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate. PMID:22399913

  15. Unified system for holographic measurement in fluid and solid mechanics: application of the system to volumetric flow measurement in an internal combustion engine

    Science.gov (United States)

    Chan, Victor S. S.; Barnhart, Donald H.; Garner, Colin P.; Halliwell, Neil A.; Coupland, Jeremy M.

    1999-10-01

    This paper reports holographic measurements of full-field 3D flows inside a production geometry 4-stoke internal combustion engine with extensive optical access through both the cylinder wall and the piston crown. The seeded flow is recorda at two instants as a reflection hologram of high numerical aperture. A purpose built holographic camera using a phase conjugate holographic optical element is used to compensate for the gross aberrations caused by imaging through a thick walled, glass cylinder. Fiber-optic, conjugate recognition and subsequent correlation of the complex amplitude recorded by the hologram facilitates sub- wavelength measurement of particle displacement without directional ambiguity. Preliminary measurements of the flow field within the cylinder at the bottom of the induction stroke are discussed. The results clearly show the potential of this technique to extract 3D velocity information in hostile environments.

  16. Heating capabilities of the Hotline and Autoline at low flow rates.

    Science.gov (United States)

    Schnoor, Joerg; Weber, Ingo; Macko, Stephan; Heussen, Nicole; Rossaint, Rolf

    2006-04-01

    At low flow rates, fluid warmers using coaxial warming tubes are superior in preventing heat loss. This laboratory investigation was performed in order to compare the heating capabilities of two coaxial fluid warmers. The Hotline and the Autoline were investigated by using normal saline at various flow rates (10-99 ml x h(-1)). Final infusion temperatures were measured six times in a row at the end of the tubing by using a rapid-response thermometer. Final temperatures were compared with those of infusions, which passed through disposable i.v. tubing covered and warmed using an 'off label' convective air warming system (WarmTouch). Measurements were performed at two different room temperatures (20 and 24 degrees C). Each group was analyzed with respect to differences between various flow rates as well as differences between the groups at comparable flow rates by using a three-way anova with multiple comparisons according to Tukey's procedure. Significance was defined at P flow rates efficiently above 34 degrees C, with the Hotline being more effective than the Autoline (P flow rates (10-60 and 80 ml x h(-1)), the Autoline demonstrated lower infusion temperatures throughout elevated room temperature at flow rates between 20 and 90 ml x h(-1). Both devices heated infusions more efficiently compared with 'off label used' convective air warmer (each with P flow rates. However, the heating capability of the Hotline was superior and can further be increased at low flow rates by increasing the room temperature.

  17. [The Effect of Dialysate Flow Rate on Dialysis Adequacy and Fatigue in Hemodialysis Patients].

    Science.gov (United States)

    Cha, Sun Mi; Min, Hye Sook

    2016-10-01

    In this single repeated measures study, an examination was done on the effects of dialysate flow rate on dialysis adequacy and fatigue in patients receiving hemodialysis. This study was a prospective single center study in which repeated measures analysis of variance were used to compare Kt/V urea (Kt/V) and urea reduction ratio (URR) as dialysis adequacy measures and level of fatigue at different dialysate flow rates: twice as fast as the participant's own blood flow, 500 mL/min, and 700 mL/min. Thirty-seven hemodialysis patients received all three dialysate flow rates using counterbalancing. The Kt/V (M±SD) was 1.40±0.25 at twice the blood flow rate, 1.41±0.23 at 500 mL/min, and 1.46±0.24 at 700 mL/min. The URR (M±SD) was 68.20±5.90 at twice the blood flow rate, 68.67±5.22 at 500 mL/min, and 70.11±5.13 at 700 mL/min. When dialysate flow rate was increased from twice the blood flow rate to 700 mL/min and from 500 mL/min to 700 mL/min, Kt/V and URR showed relative gains. There was no difference in fatigue according to dialysate flow rate. Increasing the dialysate flow rate to 700 mL/min is associated with a significant nicrease in dialysis adequacy. Hemodialysis with a dialysate flow rate of 700 mL/min should be considered in selected patients not achieving adequacy despite extended treatment times and optimized blood flow rate.

  18. Litter ammonia losses amplified by higher air flow rates

    Science.gov (United States)

    ABSTRACT Broiler litter utilization has largely been associated with land application as fertilizer. Reducing ammonia (NH3) released from litter enhances its fertilizer value and negates detrimental impacts to the environment. A laboratory study was conducted to quantify the effect of air flow var...

  19. Behavior of free surface vortices in cylindrical vessel under fluctuating flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Hideaki Monji; Toshinori Akimoto; Daisuke Miwa [Graduate School of System and Information Engineering University of Tsukuba Tsukuba 305-8573 (Japan); Hideaki Kamide [New Thechnology Development Group, Advanced Technology Division O-arai Engineering Center, Japan Nucler Cycle Development Institute O-arai 311-1393 (Japan)

    2005-07-01

    Full text of publication follows: This paper deals with characteristics of free surface vortices at an upper plenum in a Fast Breeder Reactor. The free surface vortex is one of the most important mechanisms causing gas entrainment. Because the gas entrainment affects on reactivity of the reactor, the estimation of the onset condition of gas entrainment is an important factor for design of the reactor. The gas entrainment due to the free surface vortex is a time series phenomena; (i) formation of a vortex dimple on the free surface, (ii) development of the gas core of the vortex by a downward flow, and (iii) gas entrainment by the separation of bubbles at a tip of the gas core. In this study, the gas entrainment by the bubble separation is focused on and the unsteady behavior of the gas core by the fluctuations of the flow conditions is investigated experimentally. In the experiment, the free surface vortex was generated in a cylindrical vessel with a tangential slit injection and the downward flow was by a suction pipe at the bottom. The working fluid was water and the vessel is under the atmospheric air. The gas core developed due to the circulating and downward flow. In order to know the unsteady behavior of the gas core, the injection flow rate into the vessel was changed as a sine wave, and the time series of the gas core geometry was measured by a stereo image processing. The results of the study are mainly as follows; (i) The gas core length changed with the water flow rate but the shape of the fluctuation of gas core length was not a sine wave. The core length decreased suddenly when the water flow rate decreased. This corresponds that the characteristic time of the flow for the increasing flow rate is longer than that for the decreasing flow rate. (ii) The gas core length under the fluctuating flow rate was shorter than that under the condition of the fixed water flow rate which is the same as the maximum water flow rate of the fluctuating flow. This fact

  20. Measurement of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Kalyanova, Olena; Jensen, Rasmus Lund; Heiselberg, Per

    2007-01-01

    Air flow rate in a naturally ventilated space is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes three different methods to measure the air flow in a full-scale outdoor test facility with a nat...

  1. Economic method for measuring ultra-low flow rates of fluids

    Science.gov (United States)

    Bogdanovic, J. A.; Keller, W. F.

    1970-01-01

    Capillary tube flowmeter measures ultra-low flows of very corrosive fluids /such as chlorine trifluoride and liquid fluorine/ and other liquids with reasonable accuracy. Flowmeter utilizes differential pressure transducer and operates on the principle that for laminar flow in the tube, pressure drop is proportional to flow rate.

  2. A high rate flow-focusing foam generator

    OpenAIRE

    Lorenceau, Elise; Sang, Yann Yip Cheung; Hohler, Reinhard; Cohen-Addad, Sylvie

    2006-01-01

    We use a rigid axisymetric microfluidic flow focusing device to produce monodisperse bubbles, dispersed in a surfactant solution. The gas volume fraction of the dispersion collected out of this device can be as large as 90%, demonstrating that foam with solid-like viscoelastic properties can be produced in this way. The polydispersity of the bubbles is so low that we observe crystallization of our foam. We measure the diameter of the bubbles and compare these data to recent theoretical predic...

  3. Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

    Science.gov (United States)

    Kenny, R Jeremy; Hulka, James R.

    2008-01-01

    Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

  4. Normalizing parameters for the critical flow rate of simple fluids through nozzles

    Science.gov (United States)

    Hendricks, R. C.

    1974-01-01

    It is shown that two-phase critical nozzle flow of simple fluids almost obeys the principle of corresponding states. Quantum fluid departures from the principle are resolved as a function of temperature for para-hydrogen and helium. The critical flow rates are normalized, using a normalizing parameter for which the critical flow rates of all simple fluids reduce to a single isothermal curve. The expression obtained for the normalizing parameter is shown to provide good agreement with the experiment for the critical flow rates of nitrogen, oxygen, and para-hydrogen.

  5. Flow Rates in Liquid Chromatography, Gas Chromatography and Supercritical Fluid Chromatography: A Tool for Optimization

    Directory of Open Access Journals (Sweden)

    Joris Meurs

    2016-08-01

    Full Text Available This paper aimed to develop a standalone application for optimizing flow rates in liquid chromatography (LC, gas chromatography (GC and supercritical fluid chromatography (SFC. To do so, Van Deemter’s equation, Knox’ equation and Golay’s equation were implemented in a MATLAB script and subsequently a graphical user interface (GUI was created. The application will show the optimal flow rate or linear velocity and the corresponding plate height for the set input parameters. Furthermore, a plot will be shown in which the plate height is plotted against the linear flow velocity. Hence, this application will give optimized flow rates for any set conditions with minimal effort.

  6. Rate of coronary flow adaptation in response to changes in heart rate before and during anesthesia for coronary artery surgery

    NARCIS (Netherlands)

    van Wezel, H. B.; Kal, J. E.; Vergroesen, I.; Vroom, M. B.; de Graaf, R.; Dankelman, J.; Porsius, M.; Spaan, J. A.

    1996-01-01

    BACKGROUND: The rate of adaptation of coronary blood flow in response to stepwise changes in heart rate (HR) has been extensively studied in dogs and goats to improve our understanding of the dynamics of coronary regulation processes and their pathophysiology and to obtain time constants for

  7. Linear genetic programming for time-series modelling of daily flow rate

    Indian Academy of Sciences (India)

    In this study linear genetic programming (LGP), which is a variant of Genetic Programming, and two versions of Neural Networks (NNs) are used in predicting time-series of daily flow rates at a station on Schuylkill River at Berne, PA, USA. Daily flow rate at present is being predicted based on different time-series scenarios.

  8. Effect of Retarding Force on Mass Flow Rates of Fluid at Different ...

    African Journals Online (AJOL)

    ... mathematical model and software visualization to view the effect of retarding forces on the mass flow rate in term of visualization. C-sharp (C#) is the chosen program and this enable compares and us to determine the mass flow rates patterns in relation to retarding force in form of graphical tables at different temperature.

  9. Drop-box Weir for Measuring Flow Rates Under Extreme Flow Conditions

    Science.gov (United States)

    Sediment and large rocks often are transported in runoff during extreme events. The sediment can deposit in a runoff-measuring structure and give erroneous readings. The drop-box weir (DBW) is one of only a few flow-measuring devices capable of measuring sediment-laden flows. Recent studies have ...

  10. Influence of transient strain rates on material flow stress and microstructure evolution

    Science.gov (United States)

    Dierdorf, Jens; Lohmar, Johannes; Hirt, Gerhard

    2017-10-01

    A comprehensive knowledge about the material flow stress is a key parameter for a reliable design of hot forming processes using Finite Element (FE) software codes. Due to the microstructure evolution caused by the interaction of hardening and softening phenomena that take place during hot forming operations, the material flow stress is influenced by strain rate and temperature. While transient strain rates and temperatures typically characterize the industrial forming processes, the flow curves used in FE simulations are normally determined at arbitrary constant temperatures and strain rates. To calculate the flow stress evolution in between the measured strain rates, FE programs use linear interpolation. Hence, the material relaxation behavior caused by the microstructure evolution during transient strain rates is not considered. Previous investigations by various authors have shown that for a rapid strain rate change by one order of magnitude significant deviations between measured flow stress and linear interpolation appear before the flow stress approximates the flow curve obtained at the new constant strain rate again. However as mentioned before, industrial forming processes are characterized by more or less smooth than instantaneous changes in strain rate. Therefore, in this study, changing strain rates with different linear slopes are investigated. For this purpose, isothermal cylinder compression tests of an industrial case hardening steel are conducted at elevated temperatures. The resulting flow stress is compared with the linear interpolation of the flow curves determined at constant strain rates. Additionally, the grain size evolution during the strain rate change is analyzed to better understand the microstructural changes. The current investigation shows that the slope of the strain rate increase significantly influences the deviation from the linear interpolation. This observation can be explained by the time dependent microstructure evolution

  11. Cold flow mixing rate data for pulverized coal reactors

    Energy Technology Data Exchange (ETDEWEB)

    Memmott, V.J.; Smoot, L.D.

    1978-05-01

    To elucidate the mixing characteristics of particle-laden, confined jets in entrained-bed coal gasifiers, Brigham Young University examined the effects of velocity, density, injection angle, particle loading level, and particle size on the rate of particle and gas mixing. Researchers measured the gas velocity, particle mass flux, and gas composition at various radial and axial locations downstream of the primary jet exit plane. Increases in injection angle and secondary velocity significantly raised gas and particle mixing rates, while the effects of other variables were much less significant. Dispersion of particles lagged that of the gas in all cases investigated. Controlling the mixing processes may lead to increases in combustion efficiency or to a reduction in the rate of pollutant formation.

  12. Characteristics of the saliva flow rates of minor salivary glands in healthy people.

    Science.gov (United States)

    Wang, Zhen; Shen, Ming-Ming; Liu, Xiao-Jing; Si, Yan; Yu, Guang-Yan

    2015-03-01

    To investigate the normal range and characteristics of saliva secretion in the minor salivary glands (MSGs). The flow rates of MSGs were measured in 4 anatomical locations of oral mucosa, and the relationship between MSG flow rates and whole saliva flow rates were assessed in 300 healthy subjects stratified by age and sex. An additional 30 young females were further evaluated for flow symmetry, effects of stimulation, circadian effects in MSGs, and the relationship with the flow rates of major salivary glands. (1) The mean saliva flow rates were 2.10 ± 0.66 (lower labial glands), 2.14 ± 0.62 (upper labial glands), 2.88 ± 0.72 (buccal glands) and 2.15 ± 0.51 (palatal glands) μl/min/cm(2), respectively. The flow rate of buccal glands was significantly higher than the rates of SMGs in other locations (P 0.05), right vs. left (P > 0.05), and citric acid (2.5%) stimulation (P > 0.05). (4) Only labial MSG displayed a significant secretory circadian rhythm with the highest rate in the evening (P glands and that of unstimulated whole saliva (r = 0.195, P = 0.007). Our findings provide a reference for functional evaluation of MSGs and for donor site selection of MSG transplantation for treatment of severe dry eye syndrome. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. The effect of temperature fluctuations of reaction rate constants in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.; Antaki, P. J.; Kassar, G. M.

    1981-01-01

    Current models of turbulent reacting flows frequently use Arrhenius reaction rate constants obtained from static or laminar flow theory and/or experiments, or from best fits of static, laminar, and turbulent data. By treating the reaction rate constant as a continuous random variable which is temperature-dependent, the present study assesses the effect of turbulent temperature fluctuations on the reaction rate constant. This model requires that a probability density function (PDF) describing the nature of the fluctuations be specified. Three PDFs are examined: the clipped Gaussian, the beta PDF, and the ramp model. All the models indicate that the reaction rate constant is greater in a turbulent flow field than in an equivalent laminar flow. In addition, an amplification ratio, which is the ratio of the turbulent rate constant to the laminar rate constant, is defined and its behavior as a function of the mean temperature fluctuations is described

  14. Computed Tomography Angiography With High Flow Rates: An In Vitro and In Vivo Feasibility Study.

    Science.gov (United States)

    Mihl, Casper; Kok, Madeleine; Wildberger, Joachim E; Turek, Jakub; Muehlenbruch, Georg; Das, Marco

    2015-07-01

    The aims of this study were to test high-flow application of contrast media (CM) using novel high-flow needles and to assess injection- and flow-related parameters in a circulation phantom and in an in vivo population. A circulation phantom simulating physiological parameters was used. Preheated CM (300 mg/mL) was injected at flow rates varying between 5 and 15 mL/s through a novel 18-gauge high-flow intravenous injection needle. In addition, feasibility of these high-flow needles was tested with administration of flow rates of 9 mL/s in 20 patients referred for pre-transcatheter aortic valve implantation assessment. Injection parameters (eg, peak pressures, peak flow rates) in both phantom and in vivo setup were continuously monitored by a data acquisition program. Attenuation at predefined levels of the aorta (eg, aortic root to common femoral arteries) was measured in all patients to determine clinical applicability. In the phantom setup, injection rates up to 15 mL/s were feasible. An enhancement plateau was reached at 11 mL/s (464 [20] HU). In patients, no pressure- or flow-related complications (eg, extravasation) were recorded (mean [SD] peak pressure, 154 [8] psi; mean [SD] peak flow rate, 9.2 [0.1 mL/s; range, 9.1-9.6]). Diagnostic attenuation values were reached at all predefined levels of the aorta (330.8 [113.1] HU to 622.9 [81.5] HU). These results indicate that injections with 9 mL/s using high-flow injection needles are safe. The pressure limit of 325 psi was not reached, and the injections resulted in diagnostic attenuation values. Using this dedicated needle, high flow rates should not be considered a drawback for CM application in routine CT angiography examinations.

  15. A generalized Forchheimer radial flow model for constant-rate tests

    Science.gov (United States)

    Liu, Ming-Ming; Chen, Yi-Feng; Zhan, Hongbin; Hu, Ran; Zhou, Chuang-Bing

    2017-09-01

    Models used for data interpretation of constant-rate tests (CRTs) are commonly derived with the assumption of Darcian flow in an idealized integer flow dimension, where the non-Darcian nature of fluid flow and the complexity of flow geometry are disregarded. In this study, a Forchheimer's law-based analytical model is proposed with the assumption of buildup (or drawdown) decomposition for characterizing the non-Darcian flow in a generalized radial formation where the flow dimension n may become non-integer. The proposed model immediately reduces to Barker's (1988) model for Darcian flow in the generalized radial formation and to Mathias et al.'s (2008) model for non-Darcian flow in a two-dimensional confined aquifer. A comparison with numerical simulations shows that the proposed model behaves well at late times for flow dimension n > 1.5. The proposed model is finally applied for data interpretation of the constant-rate pumping tests performed at Ploemeur (Le Borgne et al., 2004), showing that the intrinsic hydraulic conductivity of formations will be underestimated and the specific storage will be overestimated if the non-Darcian effect is ignored. The proposed model is an extension of the generalized radial flow (GRF) model based on Forchheimer's law, which would be of significance for data interpretation of CRTs in aquifers of complex flow geometry in which non-Darcian flow occurs.

  16. Aminophylline Improves Urine Flow Rates but Not Survival in ...

    African Journals Online (AJOL)

    Introduction: Acute kidney injury (AKI) morbidity and mortality rates remain high. Variable AKI outcomes have been reported in association with aminophylline treatment. This study evaluated AKI outcome in a group of Nigerian children treated with aminophylline. Methods: This is a retrospective study of AKI in children ...

  17. Local and Nonlocal Strain Rate Fields and Vorticity Alignment in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    Local and nonlocal contributions to the total strain rate tensor at any point in a flow are formulated from an expansion of the vorticity field in a local spherical neighborhood of radius R centered on x. The resulting exact expression allows the nonlocal (background) strain rate tensor to be obtained from the total strain rate tensor. In turbulent flows, where the vorticity naturally concentrates into relatively compact structures, this allows the local alignment of vorticity with the most e...

  18. Flow rates of large animal fluid delivery systems used for high-volume crystalloid resuscitation.

    Science.gov (United States)

    Nolen-Walston, Rose D

    2012-12-01

    Large animal species in states of shock can require particularly high flow rates for volume resuscitation and the ability to deliver adequate volumes rapidly may be a rate-limiting step. The objective of this study was to determine the maximum flow rates of common combinations of IV catheter, extension set, and fluid administration sets. University veterinary teaching hospital. In vitro experimental study. Maximum flow rates were measured using combinations of 4 IV catheters (3 14-Ga and a single 10-Ga), 2 IV catheter extension sets (small bore and large bore), and 2 types of fluid administration sets (standard 2-lead large animal coiled IV set and nonpressurized 4-lead arthroscopic irrigation set). The catheter, extension sets, and administration sets were arranged in 16 configurations, and flow rates measured in triplicate using tap water flowing into an open receptacle. Flow rates ranged from 7.4 L/h with an over-the-wire 14-Ga catheter, small-bore extension, and coil set, to 51.2 L/h using a 10-Ga catheter, no extension, and arthroscopic irrigation set. There was an increase of 1.3-8.9% in flow rates between the large- versus small-bore extension sets. Crystalloid delivery in vivo to an adult horse was 21% slower (9.1 L/h versus 11.5 L/h) than the corresponding in vitro measurement. Extremely high flow rates can be achieved in vitro using large-bore catheters and delivery systems, although the clinical necessity for rates >50 L/h has not been determined. The use of large-bore extension sets resulted in only a minimal increase in flow rate. © Veterinary Emergency and Critical Care Society 2012.

  19. In vitro simulation of in vivo pharmacokinetic model with intravenous administration via flow rate modulation.

    Science.gov (United States)

    Chen, Yuan-Cheng; Liang, Wang; Hu, Jia-Li; He, Gao-Li; Wu, Xiao-Jie; Liu, Xiao-Fang; Zhang, Jing; Hu, Xue-Qian

    2015-02-01

    The aim of this paper was to propose a method of flow rate modulation for simulation of in vivo pharmacokinetic (PK) model with intravenous injection based on a basic in vitro PK model. According to the rule of same relative change rate of concentration per unit time in vivo and in vitro, the equations for flow rate modulation were derived using equation method. Four examples from literature were given to show the application of flow rate modulation in the simulation of PK model of antimicrobial agents in vitro. Then an experiment was performed to confirm the feasibility of flow rate modulation method using levo-ornidazole as an example. The accuracy and precision of PK simulations were evaluated using average relative deviation (ARD), mean error and root mean squared error. In vitro model with constant flow rate could mimic one-compartment model, while the in vitro model with decreasing flow rate could simulate the linear mammillary model with multiple compartments. Zero-order model could be simulated using the in vitro model with elevating flow rate. In vitro PK model with gradually decreasing flow rate reproduced the two-compartment kinetics of levo-ornidazole quite well. The ARD was 0.925 % between in vitro PK parameters and in vivo values. Results suggest that various types of PK model could be simulated using flow rate modulation method without modifying the structure. The method provides uniform settings for the simulation of linear mammillary model and zero-order model based on in vitro one-compartment model, and brings convenience to the pharmacodynamic study.

  20. Passive sampling of perfluorinated chemicals in water: flow rate effects on chemical uptake.

    Science.gov (United States)

    Kaserzon, Sarit L; Vermeirssen, Etiënne L M; Hawker, Darryl W; Kennedy, Karen; Bentley, Christie; Thompson, Jack; Booij, Kees; Mueller, Jochen F

    2013-06-01

    A recently developed modified polar organic chemical integrative sampler (POCIS) provides a means for monitoring perfluorinated chemicals (PFCs) in water. However, changes in external flow rates may alter POCIS sampling behaviour and consequently affect estimated water concentrations of analytes. In this work, uptake kinetics of selected PFCs, over 15 days, were investigated. A flow-through channel system was employed with spiked river water at flow rates between 0.02 and 0.34 m s(-1). PFC sampling rates (Rs) (0.09-0.29 L d(-1) depending on analyte and flow rate) increased from the lowest to highest flow rate employed for some PFCs (MW ≤ 464) but not for others (MW ≥ 500). Rs's for some of these smaller PFCs were increasingly less sensitive to flow rate as this increased within the range investigated. This device shows promise as a sampling tool to support monitoring efforts for PFCs in a range of flow rate conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Feasibility of exhaled nitric oxide measurements at various flow rates in children with asthma.

    Science.gov (United States)

    Robroeks, Charlotte M H H T; van Vliet, Dillys; Hendriks, Han J E; Dompeling, Edward; Jöbsis, Quirijn

    2010-02-01

    Measurement of bronchial and alveolar exhaled nitric oxide (NO) levels could be of clinical importance for the treatment of asthma. To discriminate between alveolar and bronchial NO, measurements need to be assessed at various flow rates. To study the feasibility, linearity, and long-term repeatability of NO measurements at four different exhalation flow rates in children with asthma. Twenty-one children with moderate persistent asthma, aged 6-12 yrs, were included in the study. NO was measured according to the ATS/ERS guidelines, using the NIOX analyzer with flow restrictors of 30, 50, 100, and 200 ml/s. Duration of the measurements ranged from 6-10 s, depending on the flow rate. The tests were repeated 3 and 6 months after the first NO measurement. Feasibility of NO measurements at these four flow rates increased from 67% to 91% and 95% at the first, second and third visit, respectively. A significant learning effect was present. Age and lung function indices did not influence success or failure of the tests. At the first measurements occasions, no problems occurred during the NO analysis at a 100 ml/s flow rate. There was a 75-90% success rate when performing the test using flow rates of 30, 50, and 200 ml/s. However, repeating the tests resulted in a 100% success rate. Measurements were not successful if: (i) children ran out of air; (ii) NO concentration exceeded 200 ppb; (iii) the measured NO flow was unstable; and (iv) the NO plateau was not formed. This study showed good feasibility and linearity of NO measurements in asthmatic children of 6 yrs and over at flow rates between 50-200 ml/s. A significant learning effect was present. The long-term reproducibility of alveolar and bronchial NO values during 6 months was moderate. © 2010 The Authors. Journal compilation © 2010 Blackwell Munksgaard.

  2. Mercury flow experiments. 4th report Measurements of erosion rate caused by mercury flow

    CERN Document Server

    Kinoshita, H; Hino, R; Kaminaga, M

    2002-01-01

    The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a construction plan of the Material-Life Science Facility, which is consisted of a Muon Science Facility and a Neutron Scattering Facility, in order to open up the new science fields. The Neutron Scattering Facility will be utilized for advanced fields of Material and Life science using high intensity neutron generated by the spallation reaction of a 1 MW pulsed proton beam and mercury target. Design of the spallation mercury target system aims to obtain high neutron performance with high reliability and safety. Since the target system is using mercury as the target material and contains large amount of radioactive spallation products, it is necessary to estimate reliability for strength of instruments in a mercury flow system during lifetime of the facility. Piping and components in the mercury flow system would be damaged by erosion with mercury flow, since these components will be we...

  3. Effect of different river flow rates on biomarker responses in common carp (Cyprinus carpio).

    Science.gov (United States)

    Hackenberger, Branimir K; Velki, Mirna; Lončarić, Zeljka; Hackenberger, Davorka K; Ečimović, Sandra

    2015-02-01

    The present study investigated effects of different river flow rates on basal activities of selected biomarkers and the occurrence of oxidative stress in the common carp (Cyprinus carpio). Juvenile carp were exposed to different river flow rates (5-120 cm/s) by caging for 3 weeks. After this period, one half of the fish were sacrificed and used for analysis. The other half received a single intraperitoneal injection of 3-methylcholanthrene (3-MC) and after 6 days were sacrificed and used for analysis. In order to investigate whether the physical activity of carp in the environment will influence the condition status of carp, following biomarkers were measured - activities of glutathione S-transferase (GST), catalase (CAT) and ethoxyresorufin-O-deethylase (EROD) and concentration of protein carbonyls (PC). The results showed that different flow rates significantly influenced biochemical biomarkers. The basal activity of GST did not change significantly after exposure to different river flow rates, whereas the activity of CAT increased with increasing river flow rates. The application of 3-MC caused significant increases in GST and CAT activities, but there were no difference between 3-MC control and 3-MC different flow rates. The occurrence of oxidative stress as a result of exposure to increased physical activity, i.e. increased river flow rates, was confirmed by measurement of PC levels - the level of PC increased with increasing river flow rates. Measurement of EROD basal activity showed that at lower river flow rates the EROD activity increased and at higher river flow rates decreased towards control levels demonstrating a close relationship between oxidative stress, PC levels and EROD activity. Obviously, biomarker responses in carp of different condition status can differ substantially. It can be concluded that flow rate may be an important factor in biomonitoring of rivers using biomarkers and since at different locations river water flow rate can vary

  4. Analysis of Winter Low-Flow Rates in New Hampshire Streams

    Science.gov (United States)

    1990-08-01

    AD-A229 512 TI1P FILE COPY * Analysis of Winter Low- Flow Rates in New Hampshire Streams Rae Ann Melloh August 1990 a DTIC fpIm ELECTE iN O V21WOl D i...Winter Low- Flow Rates in New Hampshire Streams Rae Ann Melloh August 1990 Prepared for OFFICE OF THE CHIEF OF ENGINEERS Approved for public release...Analysis of Winter Low- Flow Rates in New Hampshire Streams RAE ANN MELLOH INTRODUCTION watercourse from the drainage area divide and water- course storage

  5. Quartz measurement in coal dust with high-flow rate samplers: laboratory study.

    Science.gov (United States)

    Lee, Taekhee; Lee, Eun Gyung; Kim, Seung Won; Chisholm, William P; Kashon, Michael; Harper, Martin

    2012-05-01

    A laboratory study was performed to measure quartz in coal dust using high-flow rate samplers (CIP10-R, GK2.69 cyclone, and FSP10 cyclone) and low-flow rate samplers [10-mm nylon and Higgins-Dewell type (BGI4L) cyclones] and to determine whether an increased mass collection from high-flow rate samplers would affect the subsequent quartz measurement by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analytical procedures. Two different sizes of coal dusts, mass median aerodynamic diameter 4.48 μm (Coal Dust A) and 2.33 μm (Coal Dust B), were aerosolized in a calm air chamber. The mass of coal dust collected by the samplers was measured gravimetrically, while the mass of quartz collected by the samplers was determined by FTIR (NIOSH Manual of Analytical Method 7603) and XRD (NIOSH Manual of Analytical Method 7500) after one of two different indirect preparations. Comparisons between high-flow rate samplers and low-flow rate samplers were made by calculating mass concentration ratios of coal dusts, net mass ratios of coal dusts, and quartz net mass. Mass concentrations of coal dust from the FSP10 cyclone were significantly higher than those from other samplers and mass concentrations of coal dust from 10-mm nylon cyclone were significantly lower than those from other samplers, while the CIP10-R, GK2.69, and BGI4L samplers did not show significant difference in the comparison of mass concentration of coal dusts. The BGI4L cyclone showed larger mass concentration of ∼9% compared to the 10-mm nylon cyclone. All cyclones provided dust mass concentrations that can be used in complying with the International Standard Organization standard for the determination of respirable dust concentration. The amount of coal dust collected from the high-flow rate samplers was found to be higher with a factor of 2-8 compared to the low-flow rate samplers but not in direct proportion of increased flow rates. The high-flow rate samplers collected more quartz compared to

  6. Validation of simultaneous volumetric and HPLC methods for the determination of pridinol mesylate in raw material.

    Science.gov (United States)

    Simionato, Laura D; Ferello, Leonardo; Stamer, Sebastián; Zubata, Patricia D; Segall, Adriana I

    2013-01-01

    Simple, sensitive, and economical simultaneous volumetric and HPLC methods for the determination of pridinol mesylate in raw material have been developed. The volumetric method is based on the reaction of pridinol with sodium lauryl sulphate in diluted sulphuric acid. Dimethyl yellow was used as indicator to detect the end point of the titration in aqueous/organic layer. The HPLC method for the determination of pridinol mesylate employs a reverse phase C18 column at ambient temperature with a mobile phase consisting of acetonitrile: 0.05 M potassium dihydrogen phosphate, pH adjusted to 5.0 (1 : 2, v/v). The flow rate was 0.8 mL/min. Quantitation was achieved with UV detection at 258 nm based on peak area. Both methods were found to be suitable for the quality control of pridinol mesylate in raw material.

  7. TWO PHASE FLOW SPLIT MODEL FOR PARALLEL CHANNELS

    African Journals Online (AJOL)

    Ifeanyichukwu Onwuka

    Volumetric Flux. ϕ. Wall Heat Addition Rate Watts. N. Number of Channels with. Lower Plenum entry and Upper plenum exit. M. Number of Cross-flow paths. K .... Phase Split Equation. One way of obtaining the additional information is to define (N+M-l) phase relationships between the liquid and vapour flows at the channel ...

  8. Tangential stretching rate (TSR) analysis of non premixed reactive flows

    KAUST Repository

    Valorani, Mauro

    2016-10-16

    We discuss how the Tangential stretching rate (TSR) analysis, originally developed and tested for spatially homogeneous systems (batch reactors), is extended to spatially non homogeneous systems. To illustrate the effectiveness of the TSR diagnostics, we study the ignition transient in a non premixed, reaction–diffusion model in the mixture fraction space, whose dependent variables are temperature and mixture composition. The reactive mixture considered is syngas/air. A detailed H2/CO mechanism with 12 species and 33 chemical reactions is employed. We will discuss two cases, one involving only kinetics as a model of front propagation purely driven by spontaneous ignition, the other as a model of deflagration wave involving kinetics/diffusion coupling. We explore different aspects of the system dynamics such as the relative role of diffusion and kinetics, the evolution of kinetic eigenvalues, and of the tangential stretching rates computed by accounting for the combined action of diffusion and kinetics as well for kinetics only. We propose criteria based on the TSR concept which allow to identify the most ignitable conditions and to discriminate between spontaneous ignition and deflagration front.

  9. Measurement and Modelling of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Heiselberg, Per; Kalyanova, Olena; Jensen, Rasmus Lund

    2008-01-01

    Air flow rate in a naturally ventilated double skin façade (DSF) is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes the results of two different methods to measure the air flow in a full......-scale outdoor test facility with a naturally ventilated double skin façade. Although both methods are difficult to use under such dynamic air flow conditions, they show reasonable agreement and can be used for experimental validation of numerical models of natural ventilation air flow in DSF. Simulations...... by the thermal simulation program, BSim, based on measured weather boundary conditions are compared to the measured air temperature, temperature gradient and mass flow rate in the DSF cavity. The results show that it is possible to predict the temperature distribution and airflow in the DSF although some...

  10. Does water content or flow rate control colloid transport in unsaturated porous media?

    Science.gov (United States)

    Knappenberger, Thorsten; Flury, Markus; Mattson, Earl D; Harsh, James B

    2014-04-01

    Mobile colloids can play an important role in contaminant transport in soils: many contaminants exist in colloidal form, and colloids can facilitate transport of otherwise immobile contaminants. In unsaturated soils, colloid transport is, among other factors, affected by water content and flow rate. Our objective was to determine whether water content or flow rate is more important for colloid transport. We passed negatively charged polystyrene colloids (220 nm diameter) through unsaturated sand-filled columns under steady-state flow at different water contents (effective water saturations Se ranging from 0.1 to 1.0, with Se = (θ - θr)/(θs - θr)) and flow rates (pore water velocities v of 5 and 10 cm/min). Water content was the dominant factor in our experiments. Colloid transport decreased with decreasing water content, and below a critical water content (Se colloid transport was inhibited, and colloids were strained in water films. Pendular ring and water film thickness calculations indicated that colloids can move only when pendular rings are interconnected. The flow rate affected retention of colloids in the secondary energy minimum, with less colloids being trapped when the flow rate increased. These results confirm the importance of both water content and flow rate for colloid transport in unsaturated porous media and highlight the dominant role of water content.

  11. Indicators of Student Flow Rates in Honduras: An Assessment of an Alternative Methodology, with Two Methodologies for Estimating Student Flow Rates. BRIDGES Research Report No. 6.

    Science.gov (United States)

    Cuadra, Ernesto; Crouch, Luis

    Student promotion, repetition, and dropout rates constitute the basic data needed to forecast future enrollment and new resources. Information on student flow is significantly related to policy formulation aimed at improving internal efficiency, because dropping out and grade repetition increase per pupil cost, block access to eligible school-age…

  12. Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Sheikh, S P; Jørgensen, J

    1990-01-01

    The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY......+. In contrast, intracoronary NPY (0.01-10 micrograms) induced a considerable degree of vasoconstriction; the reduction of blood flow rate was dose related, with a maximum reduction to 52% of control values. The effect of intracoronary NPY (1 microgram) on maximally relaxed arterioles elicited by 30 s...... of ischemia was studied in separate experiments during reactive hyperemia. NPY induced a decrease in maximum blood flow during reactive hyperemia (166.6 vs. 214.6% of preocclusive blood flow rate, mean values; P = 0.05), an increase in the cumulative excess blood flow (61.0 vs. 35.3 ml/100 g; P = 0...

  13. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  14. Inspiratory flow rates during hard work when breathing through different respirator inhalation and exhalation resistances.

    Science.gov (United States)

    Coyne, Karen; Caretti, David; Scott, William; Johnson, Arthur; Koh, Frank

    2006-09-01

    There has been a long-standing debate regarding the adequacy of airflow rates used in respirator certification testing and whether these test flow rates underestimate actual values. This study investigated breath by breath inspiratory peak flow rate, minute ventilation, and instantaneous flow rates of eight young, healthy volunteers walking on a treadmill at 80-85% of maximal aerobic capacity until exhaustion while wearing an air-purifying respirator with one of eight combinations of inhalation and exhalation resistance. An analysis of variance was performed to identify differences among the eight conditions. Scheffe's post hoc analysis indicated which means differed. The group of conditions with the highest average value for each parameter was identified and considered to represent a worst-case scenario. Data was reported for these conditions. A Gaussian distribution was fit to the data and the 99.9% probability levels determined. The 99.9% probability level for the peak and instantaneous flow rates were 374 L/min and 336 L/min, respectively. The minute ventilation distribution was not Gaussian. Less than 1% of the recorded minute ventilations exceeded 135 L/min. Instantaneous flow rates exceeded the National Institute for Occupational Safety and Health's respirator test standards of 64, 85, and 100 L/min constant flow 91%, 87%, and 82% of the time, respectively. The recorded minute ventilations exceeded the 40 L/min minute ventilation test standard (for tests with a sinusoidal flow pattern) 100% of the time. This study showed that young, healthy respirator wearers generated peak flow rates, minute ventilations, and instantaneous flow rates that consistently exceeded current test standards. Their flow rates should be higher than those of a respirator wearer performing occupational work and could be considered upper limits. Testing respirators and respirator cartridges using a sinusoidal breathing pattern with a minute ventilation of 135 L/min (peak flow rate

  15. Erythrocyte filtrability measurement by the initial flow rate method.

    Science.gov (United States)

    Hanss, M

    1983-01-01

    A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5 mu Nucleopore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about +/- 10%. The filtration index is shown to be an intrinsic RBC filterability property.

  16. Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation

    DEFF Research Database (Denmark)

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed

    2017-01-01

    Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented....

  17. Flow rate dependency of critical wall shear stress in a radial-flow cell

    DEFF Research Database (Denmark)

    Detry, J.G.; Jensen, Bo Boye Busk; Sindic, M.

    2009-01-01

    In the present work, a radial-flow cell was used to study the removal of starch particle aggregates from several solid substrates (glass, stainless steel, polystyrene and PTFE) in order to determine the critical wall shear stress value for each case. The particle aggregates were formed by aspersi...

  18. Synthesis of Core@Shell Nanostructures in a Continuous Flow Droplet Reactor: Controlling Structure through Relative Flow Rates.

    Science.gov (United States)

    Santana, Joshua S; Koczkur, Kallum M; Skrabalak, Sara E

    2017-06-20

    Bimetallic nanostructures are primarily synthesized in small volume batches. However, droplet-based reactors are receiving attention due to their ability to maintain thermal and compositional equilibrium within and between droplets, enabling flow operations for inline analyses and the scale-up of nanomaterial syntheses. Here, the syntheses of shape-controlled core@shell Au@Pd nanostructures with variable shell thicknesses are reported through control of the relative flow rates of reagents within the microreactor. Specifically, Pd shells were grown on cubic or octahedral Au seeds, selected as a model system. In batch reactions, shell thickness is determined by precursor concentration; however, as shown here, precursor feedstock concentration can be held constant, with the precursor concentration within the droplets being controlled through relative flow rates. This approach allows process conditions to be modified inline rather than from batch to batch to achieve particles with different shell thicknesses, and this procedure should be applicable to other multicomponent systems.

  19. Standard blood flow rates of cardiopulmonary bypass are adequate in awake on-pump cardiac surgery.

    Science.gov (United States)

    Porizka, Michal; Stritesky, Martin; Semrad, Michal; Dobias, Milos; Dohnalova, Alena; Korinek, Josef

    2011-04-01

    Standard blood flow rates for cardiopulmonary bypass have been assumed to be the same for awake cardiac surgery with thoracic epidural anesthesia (TEA) as for general anesthesia. However, compared with general anesthesia, awake cardiac surgery with epidural anesthesia may be associated with higher oxygen consumption and may result in lactic acidosis when standard blood flow rates were used. The aim of our study was to investigate if standard blood flow rates are adequate in awake cardiac surgery. Forty-five patients undergoing elective on-pump cardiac surgery were assigned to receive either epidural (Group TEA, n=15), combined (Group TEA-GA, n=15) or general (Group GA, n=15) anesthesia. To monitor the adequacy of standard blood flow rates, arterial lactate, acid base parameters, and central venous and jugular bulb saturation were measured at six time points (before, during, and after the surgery) in all groups. Blood flow rates were adjusted when needed. No lactic acidosis has developed in any group (p=NS). TEA as compared with TEA-GA and GA groups had lower central venous (67±4%, 75±11%, and 72±13%, respectively, pflow rates adjustments in any study group and no ventilatory support in TEA group were required. Under careful monitoring, the use of standard blood flow rates is adequate for patients undergoing awake on-pump normothermic cardiac surgery. Copyright © 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

  20. The Effect of Electric Current and Strain Rate on Serrated Flow of Sheet Aluminum Alloy 5754

    Science.gov (United States)

    Zhao, Kunmin; Fan, Rong; Wang, Limin

    2016-03-01

    Electrically assisted tensile tests are carried out on sheet aluminum alloy AA5754 at electric current densities ranging from 0 to 30.4 A/mm2 and strain rates ranging from 10-3 to 10-1 s-1. The strain rate sensitivity and the serrated flow behavior are investigated in accordance with dynamic strain aging mechanism. The strain rate sensitivity changes from negative to positive and keeps increasing with current density. The tendency toward serrated flow is characterized by the onset of Portevin-Le Chatelier (PLC) instabilities, which are influenced by strain rate, temperature, and electric current. The evolutions of three types of serrated flow are observed and analyzed with respect to strain rate and current density. The magnitude of serration varies with strain rate and current density. The serrated flow can be suppressed by a high strain rate, a high temperature, or a strong electric current. The threshold values of these parameters are determined and discussed. Conventional oven-heated tensile tests are conducted to distinguish the electroplasticity. The flow stress reduces more in electrically assisted tension compared to oven-heated tension at the same temperature level. The electric current helps suppress the serrated flow at the similar temperature level of oven-heating.

  1. Customer Order Flow, Intermediaries, and Discovery of the Equilibrium Risk-Free Rate

    NARCIS (Netherlands)

    Menkveld, A.J.; Sarkar, A.; van der Wel, M.

    2012-01-01

    Macro announcements change the equilibrium risk-free rate. We find that Treasury prices reflect part of the impact instantaneously, but intermediaries rely on their customer order flow after the announcement to discover the full impact. This customer flow informativeness is strongest when analyst

  2. Characterisation of medical microfluidic systems regarding fast changing flow rates using optical front tracking methods.

    Science.gov (United States)

    Schroeter, Joerg; Del Bianco, Lino; Damiani, Christian; Klein, Stephan; Nestler, Bodo

    2017-10-01

    The presented optical flow metering methods are appropriate to characterise the dynamic properties of microfluidic systems. The dynamic behaviour of clinical or medical devices, micro pumps and flow sensors based on thermal methods were investigated. The Camera-System covers a flow range from 50nl/min to 500µl/min. The uncertainty is less than 4%, sample rates up to 5kS/s. The Displacement-Sensor-System covers a flow range between 100µl/min and 50ml/min. The uncertainty is less than 3% at sample rates up to 49kS/s. It was shown that measuring pulsating flow rates with thermal flow sensors is possible, but the signal is low pass filtered. The low pass behaviour is determined by the thermal properties, thermal resistance and heat capacity, of the flow channel. But the mean flow rate was always measured properly. The fluidic properties of two different types of micro pumps were examined and characterised exemplary. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Passive sampling of perfluorinated chemicals in water: Flow rate effects on chemical uptake

    NARCIS (Netherlands)

    Kaserzon, S.L.; Vermeirssen, E.L.M.; Hawker, D.W.; Kennedy, K.; Bentley, C.; Thompson, J.; Booij, K.; Mueller, J.F.

    2013-01-01

    A recently developed modified polar organic chemical integrative sampler (POCIS) provides a means for monitoring perfluorinated chemicals (PFCs) in water. However, changes in external flow rates may alter POCIS sampling behaviour and consequently affect estimated water concentrations of analytes. In

  4. The relationship between sap-flow rate and sap volume in dormant sugar maples

    Science.gov (United States)

    William J. Gabriel; Russell S. Walters; Donald W. Seegrist

    1972-01-01

    Sap-flow rate is closely correlated with the sap volume produced by dormant sugar maple trees (Acer saccharum Marsh.) and could be used in making phenotypic selections of trees for superior sap production.

  5. Regional variations in nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B

    1991-01-01

    hyperaemic response was demonstrated at both the medial and lateral aspect of the leg. As for the degree of hyperaemia and the absolute blood flow rates in the different phases, there were some deviations between the medial and the lateral locations. However, a highly significant positive correlation......The purpose of the study was to investigate possible regional variations in recently discovered nocturnal fluctuations in subcutaneous blood flow rates. Approximately 90 min after going to sleep, a 100% blood flow rate increment, lasting about 100 min, has been demonstrated in the distal and medial...... aspect of the right lower leg of normal human subjects. In the present study subcutaneous adipose tissue blood flow rates were measured simultaneously in the right and left lower legs of 16 normal human subjects over 12-20 h ambulatory conditions. The 133Xe wash-out technique, portable CdTe(Cl) detectors...

  6. The effects of antioxidant vitamin supplementation on expiratory flow rates at rest and during exercise.

    Science.gov (United States)

    Chenoweth, Leonie M; Smith, Joshua R; Ferguson, Christine S; Downey, Amy E; Harms, Craig A

    2015-10-01

    Previous studies suggest that pulmonary function is associated with fruit and vegetable consumption and plasma concentrations of antioxidant vitamins. Also, expiratory flow limitation (EFL) has been reported to limit ventilation during exercise in healthy individuals. We hypothesized antioxidant vitamin supplementation (AVS) would increase resting expiratory flow rates in healthy subjects and reduce EFL during exercise. Ten healthy, nonsmoking subjects (5 M/5 W), consuming flow rates (FEF25-75, FEF50) by ~9%. Following AVS, %EFL was significantly reduced by ~15% at minute 15, 20, and end-exercise with no change (p > 0.05) in end-expiratory lung volumes. Breathing frequency and ratings of perceived exertion and dyspnea were also lower (p 0.05) were evident at rest or during exercise with PLA. These results suggest that AVS can increase TAS, improve resting expiratory flow rates and reduce EFL during exercise in healthy subjects who are not meeting fruit and vegetable recommendations.

  7. Oral glucose retention, saliva viscosity and flow rate in 5-year-old children.

    Science.gov (United States)

    Negoro, M; Nakagaki, H; Tsuboi, S; Adachi, K; Hanaki, M; Tanaka, D; Takami, Y; Nakano, T; Kuwahara, M; Thuy, T T

    2000-11-01

    There are significant differences of glucose retention in site-specificity and individuals. Sixty-two 5-year-old nursery schoolchildren participated in this study on the relation between the viscosity of saliva and flow rate and glucose retention. Each child was instructed to rinse his/her mouth with a glucose solution (0.5 M, 5 ml) and then to spit out. Three minutes after rinsing, glucose retention was determined. Resting saliva was collected by a natural outflow method, then the flow rate was determined. A rotational viscometer was used to determine the viscosity. Glucose retention and flow rate were correlated at the left maxillary primary molars, and glucose retention and viscosity were correlated at the maxillary central primary incisors. It was concluded that glucose retention after glucose mouth rinsing was site-specific, and that glucose retention and the index of decayed, missing and filled primary teeth (dmft) were slightly correlated with the salivary viscosity and flow rate.

  8. The effect of carbon dioxide flow rate on the euthanasia of laboratory mice

    National Research Council Canada - National Science Library

    Moody, CM; Chua, B; Weary, DM

    2014-01-01

    .... Sensations of dyspnea may explain why rodents find CO2 concentrations >3% aversive. This study aimed to assess the effect of CO2 flow rates on time between the onset of dyspnea and various measures of insensibility...

  9. Measuring and modelling air mass flow rate in the injection stretch blow moulding process

    OpenAIRE

    Salomeia, Y.; Menary, G. H.; Armstrong, C G; Nixon, J; S. Yan

    2016-01-01

    The injection stretch blow moulding process involves the inflation and stretching of a hot preform into a mould to form bottles. A critical process variable and an essential input for process simulations is the rate of pressure increase within the preform during forming, which is regulated by an air flow restrictor valve. The paper describes a set of experiments for measuring the air flow rate within an industrial ISBM machine and the subsequent modelling of it with the FEA package ABAQUS. Tw...

  10. Long-Run Determinants of the Real Exchange Rate; A Stock-Flow Perspective

    OpenAIRE

    Hamid Faruqee

    1994-01-01

    This paper examines the long-run determinants of the real exchange rate from a stock-flow perspective. The empirical analysis estimates a long-run relationship between the real exchange rate, net foreign assets, and other factors affecting trade flows. Using postwar data for the United States and Japan, cointegration analysis supports the finding that the structural factors underlying each country's net trade and net foreign asset positions determine the long-run path for the real value of th...

  11. The effect of carbon dioxide flow rate on the euthanasia of laboratory mice.

    Science.gov (United States)

    Moody, C M; Chua, B; Weary, D M

    2014-10-01

    Laboratory rodents are commonly euthanized by exposure to gradually increasing concentrations of carbon dioxide (CO2). Current recommended flow rates range between 10 and 30% chamber vol/min and result in insensibility before exposure to painful concentrations (humans dyspnea is associated with a negative affective experience. Sensations of dyspnea may explain why rodents find CO2 concentrations >3% aversive. This study aimed to assess the effect of CO2 flow rates on time between the onset of dyspnea and various measures of insensibility (recumbency, loss of the righting reflex and loss of the pedal withdrawal reflex) to identify flow rates that minimize the potential experience of dyspnea. The results of this study indicate that a flow rate of 50% chamber vol/min, while holding the CO2 cage concentration just below 40%, minimizes the interval between the onset of labored breathing and recumbency. Using a 50% flow rate this interval averaged (± SE) 30.3 ± 2.9 s versus 49.7 ± 2.9 s at 20% chamber vol/min (F3,22 = 7.83, P = 0.0013). Similarly, the interval between the onset of labored breathing and loss of the righting reflex averaged 38.2 ± 2.4 s at a flow rate of 50% versus 59.2 ± 2.4 s at 20% chamber vol/min of CO2 (F3,22 = 13.62, P < 0.0001). We conclude that higher flow rates reduce the duration of dyspnea, but even at the highest flow rate mice experience more than 30 s between the onset of dyspnea and the most conservative estimate of insensibility. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  12. Fluid-Structure Interaction Effects on Mass Flow Rates in Solid Rocket Motors

    Science.gov (United States)

    2015-09-02

    in Solid Rocket Motors 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) William Harrigan 5d. PROJECT NUMBER...Determination of mass flow rate in a solid rocket motor is critical in the design of a new motor due to its effect on the thrust produced. Fluid...mass flow rates. The FSI analyses with two‐way coupling provided a more accurate assessment of solid rocket motor internal ballistics. 15. SUBJECT

  13. A Distributed Flow Rate Control Algorithm for Networked Agent System with Multiple Coding Rates to Optimize Multimedia Data Transmission

    Directory of Open Access Journals (Sweden)

    Shuai Zeng

    2013-01-01

    Full Text Available With the development of wireless technologies, mobile communication applies more and more extensively in the various walks of life. The social network of both fixed and mobile users can be seen as networked agent system. At present, kinds of devices and access network technology are widely used. Different users in this networked agent system may need different coding rates multimedia data due to their heterogeneous demand. This paper proposes a distributed flow rate control algorithm to optimize multimedia data transmission of the networked agent system with the coexisting various coding rates. In this proposed algorithm, transmission path and upload bandwidth of different coding rate data between source node, fixed and mobile nodes are appropriately arranged and controlled. On the one hand, this algorithm can provide user nodes with differentiated coding rate data and corresponding flow rate. On the other hand, it makes the different coding rate data and user nodes networked, which realizes the sharing of upload bandwidth of user nodes which require different coding rate data. The study conducts mathematical modeling on the proposed algorithm and compares the system that adopts the proposed algorithm with the existing system based on the simulation experiment and mathematical analysis. The results show that the system that adopts the proposed algorithm achieves higher upload bandwidth utilization of user nodes and lower upload bandwidth consumption of source node.

  14. Risk Factors for Reduced Salivary Flow Rate in a Japanese Population: The Hisayama Study

    Directory of Open Access Journals (Sweden)

    Kenji Takeuchi

    2015-01-01

    Full Text Available The purpose of this study was to determine distinct risk factors causing reduced salivary flow rate in a community-dwelling population using a prospective cohort study design. This was a 5-year follow-up survey of 1,377 community-dwelling Japanese individuals aged ≥40 years. The salivary flow rate was evaluated at baseline and follow-up by collecting stimulated saliva. Data on demographic characteristics, use of medication, and general and oral health status were obtained at baseline. The relationship between reduced salivary flow rate during the follow-up period and its predictors was evaluated after adjustment for confounding factors. In a multivariate logistic regression model, higher age and plaque score and lower serum albumin levels were significantly associated with greater odds of an obvious reduction in salivary flow rate (age per decade, odds ratio [OR] = 1.25, 95% confidence interval [CI] = 1.03–1.51; serum albumin levels <4 g/dL, OR = 1.60, 95% CI = 1.04–2.46; plaque score ≥1, OR = 1.53, 95% CI = 1.04–2.24. In a multivariate linear regression model, age and plaque score remained independently associated with the increased rate of reduced salivary flow. These results suggest that aging and plaque score are important predictors of reduced salivary flow rate in Japanese adults.

  15. Factors influencing the flow rate through a surgical defect in human fetal membranes.

    Science.gov (United States)

    Devlieger, R; Gratacos, E; Ardon, H; Vanstraelen, S; Deprest, J

    2002-03-01

    In order to determine factors influencing the flow rate trough a created defect in human fetal membranes, an ex vivo set-up was used with fetal membranes collected from patients undergoing Caesarean section at term. The membranes were secured at the bottom of a plastic tube and traumatised with needles ranging from 14-26 Gauges (Ga), under a hydrostatic pressure of 10 to 20 cm H(2)O and an angle of 45 degrees or 90 degrees. The column was filled with amniotic fluid or Hartmann's solution. The duration of the puncture was 1 s or the time it takes to aspirate 10 ml through the needle. The flow rate through the defect in the fetal membranes and size of the defect were measured. The flow rate and defect size increased with increasing diameter of the needle. Increasing the pressure in the column resulted in a significant linear increase in the flow rate. Replacing the saline solution with amniotic fluid did not result in significant changes in the measured flow rates, except for the small needle size (24 Ga). Increasing the duration of the puncture did not result in increased flow rates, except for small needle size (24 Ga). These experiments suggest that needle diameter, angle of needle insertion, duration of the procedure, amniotic fluid pressure and composition could influence the incidence of amniotic fluid leakage following amniocentesis. Copyright 2002 John Wiley & Sons, Ltd.

  16. Experiments in a flighted conveyor comparing shear rates in compressed versus free surface flows

    Science.gov (United States)

    Pohlman, Nicholas; Higgins, Hannah; Krupiarz, Kamila; O'Connor, Ryan

    2017-11-01

    Uniformity of granular flow rate is critical in industry. Experiments in a flighted conveyor system aim to fill a gap in knowledge of achieving steady mass flow rate by correlating velocity profile data with mass flow rate measurements. High speed images were collected for uniformly-shaped particles in a bottom-driven flow conveyor belt system from which the velocity profiles can be generated. The correlation of mass flow rates from the velocity profiles to the time-dependent mass measurements will determine energy dissipation rates as a function of operating conditions. The velocity profiles as a function of the size of the particles, speed of the belt, and outlet size, will be compared to shear rate relationships found in past experiments that focused on gravity-driven systems. The dimension of the linear shear and type of decaying transition to the stationary bed may appear different due to the compression versus dilation space in open flows. The application of this research can serve to validate simulations in discrete element modeling and physically demonstrate a process that can be further developed and customized for industry applications, such as feeding a biomass conversion reactor. Sponsored by NIU's Office of Student Engagement and Experiential Learning.

  17. Direct Assessment of Vorticity Alignment with Local and Nonlocal Strain Rates in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    A direct Biot-Savart integration is used to decompose the strain rate into its local and nonlocal constituents, allowing the vorticity alignment with the local and nonlocal strain rate eigenvectors to be investigated. These strain rate tensor constituents are evaluated in a turbulent flow using data from highly-resolved direct numerical simulations. While the vorticity aligns preferentially with the intermediate eigenvector of the \\textit{combined} strain rate, as has been observed previously...

  18. Impact of flow rate on lactate uptake and gluconeogenesis in glucagon-stimulated perfused livers.

    Science.gov (United States)

    Sumida, Ken D; Urdiales, Jerry H; Donovan, Casey M

    2006-01-01

    The impact of reduced hepatic flow on lactate uptake and gluconeogenesis was examined in isolated glucagon-stimulated perfused livers from 24-h-fasted rats. After surgical isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit (KH) bicarbonate buffer, fresh bovine erythrocytes (hematocrit approximately 20%), and no added substrate. After this "washout" period, steady-state perfusions were initiated with a second reservoir containing the KH buffer, bovine erythrocytes, [U-(14)C]lactate (10,000 dpm/ml), lactate (2.5 mM), and glucagon (250 microg/ml). Perfusion flow rate was adjusted to one of five rates (i.e., 1.8, 2.7, 3.9, 7.4, and 11.0 ml.min(-1).100 g body wt(-1)). After the perfusion, the liver was dissected out and weighed so as to establish the actual flow rate per gram of liver. The resulting flow rates ranged from 0.52 to 4.03 ml.min(-1).g liver(-1). As a function of flow rate, lactate uptake rose in a hyperbolic fashion to an apparent plateau of 2.34 micromol.min(-1).g liver(-1). Fractional extraction (FX) of lactate from the perfusate demonstrated an exponential decline with increased flow rates (r=0.97). At flow rates above 1.0 ml.min(-1).g liver(-1), adjustments in FX compensated for changes in lactate delivery, resulting in steady rates of lactate uptake and gluconeogenesis. Below 1.0.min(-1).g liver(-1) the increased FX was unable to compensate for the decline in lactate delivery and lactate uptake declined rapidly. Gluconeogenesis demonstrated similar kinetics to lactate uptake, reflecting its dominant role among pathways for lactate removal under the current conditions.

  19. Salivary flow rate and pH during prolonged gum chewing in humans.

    Science.gov (United States)

    Polland, K E; Higgins, F; Orchardson, R

    2003-09-01

    Gum chewing for 20 min causes an increase in salivary flow rate and salivary pH. Most people chew gum for longer than 20 min, and our aim was to determine how whole mouth salivary flow rate and pH might adapt during prolonged gum chewing. Resting saliva was collected over 5 min; gum-stimulated saliva was collected at intervals during 90 min, chewing a single pellet (1.5 g) of mint-flavoured, sugar-free gum (n = 19). Subjects chewed at their own preferred rate and style. Both salivary flow rate and pH were increased above resting levels for the entire 90 min. The salivary flow was significantly greater (anovaP chewing. The saliva pH remained significantly higher (P pH even after 90-min chewing. When the experiment was repeated with the gum pellets replaced at 30 and 60 min (n = 9), similar increases in salivary flow rate and pH were found. In the latter experiment, there was no evidence of any cumulative effects on flow or pH. The persistent increase in salivary pH in particular could be beneficial to oral and dental health.

  20. The role of unsteady effusion rates on inflation in long-lived lava flow fields

    Science.gov (United States)

    Rader, E.; Vanderkluysen, L.; Clarke, A.

    2017-11-01

    The emission of volcanic gases and particles can have global and lasting environmental effects, but their timing, tempo, and duration can be problematic to quantify for ancient eruptions where real-time measurements are absent. Lava flows, for example, may be long-lasting, and their impact is controlled by the rate, tempo, and vigor of effusion. These factors are currently difficult to derive from the geologic record but can have large implications for the atmospheric impact of an eruption. We conducted a set of analogue experiments on lava flow inflation aiming at connecting lava morphologies preserved in the rock record to eruption tempo and dynamics through pulsating effusion rates. Inflation, a process where molten material is injected beneath the crust of an active lava flow and lifts it upwards, is a common phenomenon in basaltic volcanic systems. This mechanism requires three components: a) a coherent, insulating crust; b) a wide-spread molten core; and c) pressure built up beneath the crust from a sustained supply of molten material. Inflation can result in a lava flow growing tens of meters thick, even in flow fields that expand hundreds of square kilometers. It has been documented that rapid effusion rates tend to create channels and tubes, isolating the active part of the flow from the stagnant part, while slow effusion rates may cause crust to form quickly and seize up, forcing lava to overtop the crust. However, the conditions that allow for inflation of large flow fields have not previously been evaluated in terms of effusion rate. By using PEG 600 wax and a programmable pump, we observe how, by pulsating effusion rate, inflation occurs even in very low viscosity basaltic eruptions. We show that observations from inflating Hawaiian lava flows correlate well with experimental data and indicate that instantaneous effusion rates may have been 3 times higher than average effusion rates during the emplacement of the 23 January 1988 flow at Kīlauea (Hawai

  1. A Computational Framework to Optimize Subject-Specific Hemodialysis Blood Flow Rate to Prevent Intimal Hyperplasia

    Science.gov (United States)

    Mahmoudzadeh, Javid; Wlodarczyk, Marta; Cassel, Kevin

    2017-11-01

    Development of excessive intimal hyperplasia (IH) in the cephalic vein of renal failure patients who receive chronic hemodialysis treatment results in vascular access failure and multiple treatment complications. Specifically, cephalic arch stenosis (CAS) is known to exacerbate hypertensive blood pressure, thrombosis, and subsequent cardiovascular incidents that would necessitate costly interventional procedures with low success rates. It has been hypothesized that excessive blood flow rate post access maturation which strongly violates the venous homeostasis is the main hemodynamic factor that orchestrates the onset and development of CAS. In this article, a computational framework based on a strong coupling of computational fluid dynamics (CFD) and shape optimization is proposed that aims to identify the effective blood flow rate on a patient-specific basis that avoids the onset of CAS while providing the adequate blood flow rate required to facilitate hemodialysis. This effective flow rate can be achieved through implementation of Miller's surgical banding method after the maturation of the arteriovenous fistula and is rooted in the relaxation of wall stresses back to a homeostatic target value. The results are indicative that this optimized hemodialysis blood flow rate is, in fact, a subject-specific value that can be assessed post vascular access maturation and prior to the initiation of chronic hemodialysis treatment as a mitigative action against CAS-related access failure. This computational technology can be employed for individualized dialysis treatment.

  2. Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

    Science.gov (United States)

    Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

    2017-08-01

    Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r2 of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Silica Measurement with High Flow Rate Respirable Size Selective Samplers: A Field Study.

    Science.gov (United States)

    Lee, Taekhee; Harper, Martin; Kashon, Michael; Lee, Larry A; Healy, Catherine B; Coggins, Marie A; Susi, Pam; O'Brien, Andrew

    2016-04-01

    High and low flow rate respirable size selective samplers including the CIP10-R (10 l min(-1)), FSP10 (11.2 l min(-1)), GK2.69 (4.4 l min(-1)), 10-mm nylon (1.7 l min(-1)), and Higgins-Dewell type (2.2 l min(-1)) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio 3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2015.

  4. Acute short-term mental stress does not influence salivary flow rate dynamics.

    Directory of Open Access Journals (Sweden)

    Ella A Naumova

    Full Text Available BACKGROUND: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. METHODS: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI data were obtained. The subjects were divided into stress subgroup (S1 (psychological reactivity, stress subgroup (S2 (psychological and physiological reactivity and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. RESULTS: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. CONCLUSIONS: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine

  5. Contraction rate, flow modification and bed layering impact on scour at the elliptical guide banks

    Science.gov (United States)

    Gjunsburgs, B.; Jaudzems, G.; Bizane, M.; Bulankina, V.

    2017-10-01

    Flow contraction by the bridge crossing structures, intakes, embankments, piers, abutments and guide banks leads to general scour and the local scour in the vicinity of the structures. Local scour is depending on flow, river bed and structures parameters and correct understanding of the impact of each parameter can reduce failure possibility of the structures. The paper explores hydraulic contraction, the discharge redistribution between channel and floodplain during the flood, local flow modification and river bed layering on depth, width and volume of scour hole near the elliptical guide banks on low-land rivers. Experiments in a flume, our method for scour calculation and computer modelling results confirm a considerable impact of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater and river bed layering on the depth, width, and volume of scour hole in steady and unsteady flow, under clear water condition. With increase of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater values, the scour depth increases. At the same contraction rate, but at a different Fr number, the scour depth is different: with increase in the Fr number, the local velocity, backwater, scour depth, width, and volume is increasing. Acceptance of the geometrical contraction of the flow, approach velocity and top sand layer of the river bed for scour depth calculation as accepted now, may be the reason of the structures failure and human life losses.

  6. Milk Flow Rates From Bottle Nipples Used for Feeding Infants Who Are Hospitalized

    Science.gov (United States)

    Park, Jinhee; Thoyre, Suzanne M.; Estrem, Hayley; Nix, W. Brant

    2015-01-01

    Purpose This study tested the milk flow rates and variability in flow of currently available nipples used for bottle-feeding infants who are hospitalized. Method Clinicians in 3 countries were surveyed regarding nipples available to them for feeding infants who are hospitalized. Twenty-nine nipple types were identified, and 10 nipples of each type were tested by measuring the amount of infant formula expressed in 1 min using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation were used to compare nipples within brand and within category (i.e., Slow, Standard, Premature). Results Flow rates varied widely between nipples, ranging from 2.10 mL/min for the Enfamil Cross-Cut to 85.34 mL/min for the Dr. Brown's Y-Cut Standard Neck. Variability of flow rates among nipples of the same type ranged from a coefficient of variation of 0.05 for Dr. Brown's Level 1 Standard- and Wide-Neck to 0.42 for the Enfamil Cross-Cut. Mean coefficient of variation by brand ranged from 0.08 for Dr. Brown's to 0.36 for Bionix. Conclusions Milk flow is an easily manipulated variable that may contribute to the degree of physiologic instability experienced by infants who are medically fragile during oral feeding. This study provides clinicians with information to guide appropriate selection of bottle nipples for feeding infants who are hospitalized. PMID:26172340

  7. Milk Flow Rates From Bottle Nipples Used for Feeding Infants Who Are Hospitalized.

    Science.gov (United States)

    Pados, Britt F; Park, Jinhee; Thoyre, Suzanne M; Estrem, Hayley; Nix, W Brant

    2015-11-01

    This study tested the milk flow rates and variability in flow of currently available nipples used for bottle-feeding infants who are hospitalized. Clinicians in 3 countries were surveyed regarding nipples available to them for feeding infants who are hospitalized. Twenty-nine nipple types were identified, and 10 nipples of each type were tested by measuring the amount of infant formula expressed in 1 min using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation were used to compare nipples within brand and within category (i.e., Slow, Standard, Premature). Flow rates varied widely between nipples, ranging from 2.10 mL/min for the Enfamil Cross-Cut to 85.34 mL/min for the Dr. Brown's Y-Cut Standard Neck. Variability of flow rates among nipples of the same type ranged from a coefficient of variation of 0.05 for Dr. Brown's Level 1 Standard- and Wide-Neck to 0.42 for the Enfamil Cross-Cut. Mean coefficient of variation by brand ranged from 0.08 for Dr. Brown's to 0.36 for Bionix. Milk flow is an easily manipulated variable that may contribute to the degree of physiologic instability experienced by infants who are medically fragile during oral feeding. This study provides clinicians with information to guide appropriate selection of bottle nipples for feeding infants who are hospitalized.

  8. On rating curve variability in presence of movable bed and unsteady flow. Applications to Tuscan rivers.

    Science.gov (United States)

    Minatti, Lorenzo; Nicoletta De Cicco, Pina; Paris, Enio

    2014-05-01

    In common engineering practice, rating curves are obtained from direct stage-discharge measurements or, more often, from stage measurements coupled with flow simulations. The present work mainly focuses on the latter technique, where stage-measuring gauges are usually installed on bridges with flow conditions likely to be influenced by local geometry constraints. In such cases, backwater flow and flow transition to supercritical state may occur, influencing sediment transport capacity and triggering more intense changes in river morphology. The unsteadiness of the flow hydrograph may play an important role too, according to the velocity of its rising and falling limbs. Nevertheless, the simulations conducted to build a rating curve are often carried out with steady flow and fixed bed conditions where the afore-mentioned effects are not taken into account at all. Numerical simulations with mobile bed and different unsteady flow conditions have been conducted on some real case studies in the rivers of Tuscany (Italy), in order to assess how rating curves change with respect to the "standard" one (that is, the classical steady flow rating curve). A 1D finite volume numerical model (REMo, River Evolution Modeler) has been employed for the simulations. The model solves the 1D Shallow Water equations coupled with the sediments continuity equation in composite channels, where the overbanks are treated with fixed bed conditions while the main channel can either aggrade or be scoured. The model employs an explicit scheme with 2nd order accuracy in both space and time: this allows the correct handling of moderately stiff source terms via a local corrector step. Such capability is very important for the applications of the present work as it allows the modelling of abrupt contractions and jumps in bed bottom elevations which often occur near bridges. The outcomes of the simulations are critically analyzed in order to provide a first insight on the conditions inducing

  9. Molecule-based approach for computing chemical-reaction rates in upper atmosphere hypersonic flows.

    Energy Technology Data Exchange (ETDEWEB)

    Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert

    2009-08-01

    This report summarizes the work completed during FY2009 for the LDRD project 09-1332 'Molecule-Based Approach for Computing Chemical-Reaction Rates in Upper-Atmosphere Hypersonic Flows'. The goal of this project was to apply a recently proposed approach for the Direct Simulation Monte Carlo (DSMC) method to calculate chemical-reaction rates for high-temperature atmospheric species. The new DSMC model reproduces measured equilibrium reaction rates without using any macroscopic reaction-rate information. Since it uses only molecular properties, the new model is inherently able to predict reaction rates for arbitrary nonequilibrium conditions. DSMC non-equilibrium reaction rates are compared to Park's phenomenological non-equilibrium reaction-rate model, the predominant model for hypersonic-flow-field calculations. For near-equilibrium conditions, Park's model is in good agreement with the DSMC-calculated reaction rates. For far-from-equilibrium conditions, corresponding to a typical shock layer, the difference between the two models can exceed 10 orders of magnitude. The DSMC predictions are also found to be in very good agreement with measured and calculated non-equilibrium reaction rates. Extensions of the model to reactions typically found in combustion flows and ionizing reactions are also found to be in very good agreement with available measurements, offering strong evidence that this is a viable and reliable technique to predict chemical reaction rates.

  10. On the use of in vivo measured flow rates as boundary conditions for image-based hemodynamic models of the human aorta: implications for indicators of abnormal flow.

    Science.gov (United States)

    Gallo, D; De Santis, G; Negri, F; Tresoldi, D; Ponzini, R; Massai, D; Deriu, M A; Segers, P; Verhegghe, B; Rizzo, G; Morbiducci, U

    2012-03-01

    The purpose of this study is to investigate how the imposition of personalized, non-invasively measured blood flow rates as boundary conditions (BCs) influences image-based computational hemodynamic studies in the human aorta. We extracted from 4D phase-contrast MRI acquisitions of a healthy human (1) the geometry of the thoracic aorta with supra-aortic arteries and (2) flow rate waveforms at all boundaries. Flow simulations were carried out, and the implications that the imposition of different BC schemes based on the measured flow rates have on wall shear stress (WSS)-based indicators of abnormal flow were analyzed. Our results show that both the flow rate repartition among the multiple outlets of the aorta and the distribution and magnitude of the WSS-based indicators are strongly influenced by the adopted BC strategy. Keeping as reference hemodynamic model the one where the applied BC scheme allowed to obtain a satisfactory agreement between the computed and the measured flow rate waveforms, differences in WSS-based indicators up to 49% were observed when the other BC strategies were applied. In conclusion, we demonstrate that in subject-specific computational hemodynamics models of the human aorta the imposition of BC settings based on non-invasively measured flow rate waveforms influences indicators of abnormal flow to a large extent. Hence, a BCs set-up assuring realistic, subject-specific instantaneous flow rate distribution must be applied when BCs such as flow rates are prescribed.

  11. Can hydraulic-modelled rating curves reduce uncertainty in high flow data?

    Science.gov (United States)

    Westerberg, Ida; Lam, Norris; Lyon, Steve W.

    2017-04-01

    Flood risk assessments rely on accurate discharge data records. Establishing a reliable rating curve for calculating discharge from stage at a gauging station normally takes years of data collection efforts. Estimation of high flows is particularly difficult as high flows occur rarely and are often practically difficult to gauge. Hydraulically-modelled rating curves can be derived based on as few as two concurrent stage-discharge and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be derived much faster than a traditional rating curve based on numerous stage-discharge gaugings. In this study we compared the uncertainty in discharge data that resulted from these two rating curve modelling approaches. We applied both methods to a Swedish catchment, accounting for uncertainties in the stage-discharge gauging and water-surface slope data for the hydraulic model and in the stage-discharge gauging data and rating-curve parameters for the traditional method. We focused our analyses on high-flow uncertainty and the factors that could reduce this uncertainty. In particular, we investigated which data uncertainties were most important, and at what flow conditions the gaugings should preferably be taken. First results show that the hydraulically-modelled rating curves were more sensitive to uncertainties in the calibration measurements of discharge than water surface slope. The uncertainty of the hydraulically-modelled rating curves were lowest within the range of the three calibration stage-discharge gaugings (i.e. between median and two-times median flow) whereas uncertainties were higher outside of this range. For instance, at the highest observed stage of the 24-year stage record, the 90% uncertainty band was -15% to +40% of the official rating curve. Additional gaugings at high flows (i.e. four to five times median flow) would likely substantially reduce those uncertainties. These first results show

  12. Effect of Various Sugary Beverages on Salivary pH, Flow Rate, and Oral Clearance Rate amongst Adults

    Directory of Open Access Journals (Sweden)

    Rinki Hans

    2016-01-01

    Full Text Available Introduction. Diet is a major aetiological factor for dental caries and enamel erosion. This study was undertaken with the aim of assessing the effect of selected locally available beverages on salivary pH, flow rate, and oral clearance rate amongst adults. Materials and Method. This clinical trial comprised 120 subjects. Test beverages undertaken were pepsi, fruit drink, coffee, and sweetened milk. Statistical analysis was carried out using SPSS version 17. Descriptive statistics, one-way ANOVA, and post hoc Tukey’s test were applied in the statistical tests. Results. It was found that salivary pH decreased for all the beverages immediately after consumption and the salivary flow rate increased after their consumption. The oral clearance rate of sweetened milk was found to be the least at 6.5 minutes and that of pepsi was found to be 13 minutes. However, the oral clearance rates of fruit drink and coffee were found to be equal at 15 minutes. Conclusion. Although it was found out that liquids cleared rapidly from the oral cavity, they had a significant cariogenic and erosive potential. Hence, it is always advised to minimise the consumption of beverages, especially amongst children and young adults to maintain a good oral health.

  13. Measuring device for purging water flow rate in control rod drive

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Hiroshi.

    1993-11-12

    The device of the present invention enables highly accurate measurement for an amount of purging water supplied to control rod drives of a BWR type reactor. That is, purging water is supplied from an inlet of a scram line of the control rod drives. A temperature measuring portion is disposed, for measuring temperature fluctuation of purging water, to a hydropressure control unit for providing pressure and flow rate of water required for supplying the purging water and scram operation. An instrumentation section is disposed for calculating the flow rate of purging water based on the measured data obtained in the section. An output device is disposed for outputting a flow rate value of the purging water based on the result of the calculation obtained therein. With such a constitution, flow rate of the purging water can be measured quantitatively at the hydropressure control unit. Accordingly, influences, such as fluctuation of reactor core temperature are reduced, and accuracy for the measurement of the purging water flow rate is improved. As a result, reactor safety and maintainability can be improved. (I.S.).

  14. Using acoustics to estimate inspiratory flow rate and drug removed from a dry powder inhaler.

    Science.gov (United States)

    Holmes, Martin S; Seheult, Jansen; Geraghty, Colm; D'Arcy, Shona; Costello, Richard W; Reilly, Richard B

    2013-01-01

    Morbidity and mortality rates of chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) are rising. There is a strong requirement for more effective management of these chronic diseases. Dry powder inhalers (DPIs) are one kind of devices currently employed to deliver medication aimed at controlling asthma and COPD symptoms. Despite their proven effectiveness when used correctly, some patients are unable to reach the inspiratory flow rate required to remove medication from the breath actuated devices and as a result, the medication does not reach the airways. This study employs an acoustic recording device, attached to a common DPI to record the audio signals of simulated inhalations. A rotameter was used to measure the flow rate through the inhaler while a milligram weighing scale was used to measure the amount of drug removed from each simulated inhalation. It was found that a strong correlation existed (R(2)>0.96) when average power, median amplitude, root mean square and mean absolute deviation were used to predict peak inspiratory flow rate. At a flow of 30 L/Min (mean absolute deviation=0.0049), it was found that 77% of the total emitted dose was removed from the inhaler. Results indicate that acoustic measurements may be used in the prediction of inspiratory flow rate and quantity of medication removed from an inhaler.

  15. Impact of physical incompatibility on drug mass flow rates: example of furosemide-midazolam incompatibility

    Science.gov (United States)

    2012-01-01

    Background Patients in intensive care units receive many drugs simultaneously but through limited venous accesses. Several intravenous therapies have to be administered through the same catheter, thus increasing the risk of physicochemical incompatibility. The purpose of this work was to assess and to quantify the impact of physical incompatibility on the mass flow rates of drugs infused simultaneously to the patient, through an in vitro study. Methods Furosemide-midazolam incompatibility was used to assess the impact of physical incompatibility on drug mass flow rates. Furosemide, midazolam, and saline were simultaneously infused. A filter was added at the end of the infusion line to retain visible particles. Two infusion conditions were tested with and without visible particles. A partial least square method on UV spectra was used to determine simultaneously the concentrations of the two drugs at the egress of the terminal extension line. The drug mass flow rate (expressed as mg/h) was calculated as the product of drug concentration versus total flow rate. Observed/theoretical mass flow rate ratios for each drug (%) were determined per infusion condition. Results Even in the absence of visible particles, precipitation of furosemide led to a drug loss estimated at between 10% and 15%. Furosemide is more impacted by interaction because the pH of the mixture is acid and this form is poorly soluble in an aqueous solution. Conclusions Physical incompatibility between furosemide and midazolam leads to a significant reduction in drug delivered to the patient and may result in treatment failure. PMID:22794308

  16. Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals.

    Science.gov (United States)

    Wong, David M; Alcott, Cody J; Wang, Chong; Hay-Kraus, Bonnie L; Buchanan, Benjamin R; Brockus, Charles W

    2010-09-01

    To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (FIO2) and other arterial blood gas variables in healthy neonatal foals. 9 healthy neonatal (3- to 4-day-old) foals. In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal FIO2, intratracheal end-tidal partial pressure of carbon dioxide, and arterial blood gas variables were measured before (baseline) and during unilateral and bilateral nasopharyngeal delivery of 50, 100, 150, and 200 mL of oxygen/kg/min. No adverse reactions were associated with administration of supplemental oxygen except at the highest flow rate, at which the foals became agitated. At individual flow rates, significant and dose-dependent increases in FIO2, PaO2, and oxygen saturation of hemoglobin (SaO2) were detected, compared with baseline values. Comparison of unilateral and bilateral delivery of oxygen at similar cumulative flow rates revealed no differences in evaluated variables. Results indicated that administration of supplemental oxygen via nasal cannulae appeared to be a highly effective means of increasing FIO2, PaO2, and SaO2 in neonatal foals. These findings may provide guidance for implementation of oxygen treatment in hypoxemic neonatal foals.

  17. Influence Of Lixiviant Flow Rate On Heap Leaching Of Low Grade Manganese Carbonate Ore

    Science.gov (United States)

    Fobi, C. M.

    2008-12-01

    A study was carried out to ascertain the influence of lixiviant flow rate on leaching of low grade manganese carbonate ore from Nsuta, Ghana, and also the levels of impurities in the resulting leachate when the ore is heap-leached for 24 hours at two different flow rates. It was found out that the lixiviant flow rate has influence on the dissolution of manganese; about 8.42% recovery of manganese was obtained when the ore was leached at a flow rate of 5 ml/min whilst 99.28% was obtained in the case of 10 ml/min. It was also observed that some levels of impurities such as iron and magnesium were in the leachate: 4075 mg/l of iron and 2575 mg/l of magnesium were in the leachate when the ore was leached at a flow rate of 5 ml/min and 2500 mg/l of iron and 3970 mg/l of magnesium were in the leachate in the case of 10 ml/min. The results indicate that leachate should be purified before the final recovery of manganese from solution.

  18. Miniaturized microDMFC using silicon microsystems techniques: performances at low fuel flow rates

    Science.gov (United States)

    Kamitani, Ai; Morishita, Satoshi; Kotaki, Hiroshi; Arscott, Steve

    2008-12-01

    This paper reports the design, fabrication and characterization of high performance miniaturized micro direct methanol fuel cells (microDMFC) functioning at room temperature under a forced low input fuel flow rate (fuel flow rate of 5.52 µL min-1 for a fuel cell surface area as small as 0.3 cm2 (corresponding to a fuel use efficiency of 14.1% at 300 K). At a lower flow rate of 1.38 µL min-1, the fuel use efficiency rises to 20.1% although the power density falls to 4.3 mW cm-2. The study revealed that improved room temperature cell performances in terms of power density can be achieved at low flow rates (fuel cell area and (ii) reducing the microchannel cross-section. The study also revealed that higher fuel use efficiencies are obtained at lower fuel flow rates. Fuel (methanol) for the anode and an oxidant (air) for the cathode are supplied via a compact serpentine network of micron-size microfluidic and gas microchannels; by using silicon microsystems techniques we also render the fuel cell compatible with other silicon technologies such as microelectronics and micro- and nanoelectromechanical systems (MEMS/NEMS).

  19. ChargeOut! : discounted cash flow compared with traditional machine-rate analysis

    Science.gov (United States)

    Ted Bilek

    2008-01-01

    ChargeOut!, a discounted cash-flow methodology in spreadsheet format for analyzing machine costs, is compared with traditional machine-rate methodologies. Four machine-rate models are compared and a common data set representative of logging skidders’ costs is used to illustrate the differences between ChargeOut! and the machine-rate methods. The study found that the...

  20. Control of skin blood flow, sweating, and heart rate - Role of skin vs. core temperature

    Science.gov (United States)

    Wyss, C. R.; Brengelmann, G. L.; Johnson, J. M.; Rowell, L. B.; Niederberger, M.

    1974-01-01

    A study was conducted to generate quantitative expressions for the influence of core temperature, skin temperature, and the rate of change of skin temperature on sweat rate, skin blood flow, and heart rate. A second goal of the study was to determine whether the use of esophageal temperature rather than the right atrial temperature as a measure of core temperature would lead to different conclusions about the control of measured effector variables.

  1. Impact of syringe size on the performance of infusion pumps at low flow rates.

    Science.gov (United States)

    Schmidt, Nadia; Saez, Claudia; Seri, Istvan; Maturana, Andrés

    2010-03-01

    To evaluate the impact of syringe size on start-up delay and the time to reach 50% and 90% of target flow rates, using two commercially available syringe infusion pumps at infusion rates of < or =1 mL/hr. Two syringes (Terumo) of different size (10-mL and 50-mL), using two syringe infusion pumps (Pump A, Terumo Terufusion Infusion Pump TE-331; and Pump B, Braun Perfusor Compact S) were studied. Effective fluid delivery was measured at 0.4 mL/hr, 0.8 mL/hr, and 1.0 mL/hr for the initial 60 mins, using the gravimetric method. Instant flow was calculated as volume difference for every 1-min interval per minute. Start-up delay was defined as time in minutes of 0 flow from the start of infusion. Syringe placement, bubble removal, infusion line priming, and positioning were standardized for all measurements, using new syringes and infusion lines. Each experiment was repeated six times. Statistical analysis was performed, using a nonparametric test (Mann-Whitney U test). None. None. None. Using the 50-mL syringe, the start-up delay was consistently higher and the time to reach 50% and 90% of target flow were significantly longer, independent of which syringe infusion pump was used. At every flow rate studied, the pumps did not reach the target flow rate before 60 mins with the 50-mL syringe. With the 10-mL syringe, target flow rate was achieved before 20 mins for both pumps. Our findings demonstrate a clinically relevant impact of syringe size on syringe infusion pump performance at low flow rates. The time to reach 50% and 90% of target flow are significantly longer, using the 50-mL syringe compared with the 10-mL syringe, and the time to reach 50% of target flow is independent of the longer start-up delay. Based on our findings, we speculate that smaller syringe sizes and higher infusion rates are preferable for continuous drug infusions, particularly when prompt establishment of the drug effect is critical.

  2. Optimal power flow calculation for power system with UPFC considering load rate equalization

    Science.gov (United States)

    Liu, Jiankun; Chen, Jing; Zhang, Qingsong

    2017-06-01

    Unified power flow controller (UPFC) device can change system electrical quantity (such as voltage, impedance, phase angle, etc.) rapidly and flexibly under the premise of maintain security, stability and reliability of power system, thus can improve the transmission power and transmission line utilization, so as to enhance the power supply capacity of the power grid. Based on a thorough study of the steady-state model of UPFC, taking load rate equalization as objective function, the optimal power flow model is established with UPFC, and simplified interior point method is used to solve it. Finally, optimal power flow of 24 continuous sections actual data is calculated on a typical day of Nanjing network. The results show that the optimal power flow calculation with UPFC can optimize the load rate equalization on the basis of eliminating line overload, improving the voltage level of local power network.

  3. Studies with sample conductivity, insertion rates, and particle deflection in a continuous flow electrophoresis system

    Science.gov (United States)

    Williams, G., Jr.

    1982-01-01

    The continuous flow electrophoresis system makes electrophoresis possible in a free-flowing film of aqueous electrolyte medium. The sample continuously enters the electrolyte at the top of the chamber and is subjected to the action of a lateral dc field. This divides the sample into fractions since each component has a distinctive electrophoretic mobility. Tests were made using monodisperse polystyrene latex microspheres to determine optimum sample conductivity, insertion rates and optimum electric field applications as baseline data for future STS flight experiments. Optimum sample flow rates for the selected samples were determined to be approximately 26 micro-liters/min. Experiments with samples in deionized water yielded best results and voltages in the 20 V/cm to 30 V/cm range were optimum. Deflections of formaldehyde fixed turkey and bovine erythrocytes were determined using the continuous flow electrophoresis system. The effects of particle interactions on sample resolution and migration in the chamber was also evaluated.

  4. A generalized volumetric dispersion model for a class of two-phase separation/reaction: finite difference solutions

    Science.gov (United States)

    Siripatana, Chairat; Thongpan, Hathaikarn; Promraksa, Arwut

    2017-03-01

    This article explores a volumetric approach in formulating differential equations for a class of engineering flow problems involving component transfer within or between two phases. In contrast to conventional formulation which is based on linear velocities, this work proposed a slightly different approach based on volumetric flow-rate which is essentially constant in many industrial processes. In effect, many multi-dimensional flow problems found industrially can be simplified into multi-component or multi-phase but one-dimensional flow problems. The formulation is largely generic, covering counter-current, concurrent or batch, fixed and fluidized bed arrangement. It was also intended to use for start-up, shut-down, control and steady state simulation. Since many realistic and industrial operation are dynamic with variable velocity and porosity in relation to position, analytical solutions are rare and limited to only very simple cases. Thus we also provide a numerical solution using Crank-Nicolson finite difference scheme. This solution is inherently stable as tested against a few cases published in the literature. However, it is anticipated that, for unconfined flow or non-constant flow-rate, traditional formulation should be applied.

  5. The influence of orifice height on flow rate of powder excipients.

    Science.gov (United States)

    Zatloukal, Z; Sklubalová, Z

    2011-12-01

    The influence of the orifice height of a cylindrical, flat-bottomed hopper on the mass flow rate of the free-flowable size fractions of sodium chloride and boric acid was investigated. It was observed that a zone of sudden acceleration of the mass flow under gravity occurred when a critical orifice height had been achieved. Based on the results, an orifice diameter equal to 12 mm with a height of between 8-16 mm is recommended for the faster flow of sodium chloride while an orifice diameter equal to 8 mm with a height of less than 8mm is appropriate for the slower flow of boric acid. In summary, the orifice height should be taken into consideration as an important parameter of a cylindrical test hopper in order to obtain a reproducible and comparable mass flow as the single-point characteristic of powder flowability.

  6. The effect of chewing gum's flavor on salivary flow rate and pH

    OpenAIRE

    Karami-Nogourani, Maryam; Kowsari-Isfahan, Raha; Hosseini-Beheshti, Mozhgan

    2011-01-01

    Background: Chewing sugar-free gums is a convenient way to increase salivary flow. Salivary flow increases in response to both gustatory (taste) and mechanical (chewing) stimuli, and chewing gum can provide both of these stimuli. The aim of this study was to compare the effect of five different flavors of sugar-free chewing gum on the salivary flow rate (SFR) and pH. Materials and Methods: Fifteen dental students volunteered at the same time on six consecutive days, to collect one minute u...

  7. In Vivo High Frame Rate Vector Flow Imaging Using Plane Waves and Directional Beamforming

    DEFF Research Database (Denmark)

    Jensen, Jonas; Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo

    2016-01-01

    oscillation (TO) estimators and only 3 directional beamformed lines. The suggested DB vector flow estimator is employed with steered plane wave transmissions for high frame rate imaging.Two distinct plane wave sequences are used: a short sequence(3 angles) for fast flow and an interleaved long sequence (21....... The long sequence has a higher sensitivity, and when used forestimation of slow flow with a peak velocity of 0.04 m/s, the SDis 2.5 % and bias is 0.1 %. This is a factor of 4 better than ifthe short sequence is used. The carotid bifurcation was scanned on a healthy volunteer, and the short sequence...

  8. The relationship between drained angle and flow rate of size fractions of powder excipients.

    Science.gov (United States)

    Sklubalová, Z; Zatloukal, Z

    2009-12-01

    The influence of powder size of chosen pharmaceutical powder excipients on drained angle as well as the correlation between drained angle and the mass flow rate of certain powder size fractions were investigated in this work. A method of the indirect estimation of the three-dimensional drained angle from the mass of the residual powder was used experimentally to study the influence of powder size fractions in range of 0.200-0.630 mm for sodium chloride, sodium citrate, potassium chloride, and potassium citrate. Failures of flow significantly increased the drained angles for powder size fraction of 0.200-0.250 mm. For the uniformly flowable powder size fraction of 0.400-0.500 mm, the faster the flow rate, the smaller drained angles were observed for excipients investigated. To estimate parameters of the flow equation, the measurement of material flow rates from the hopper of different orifice sizes is needed, while the estimation of drained angle is much easier needing only one hopper. Finally, the increase of the hopper wall angle of the standard conical hopper to 70 degrees could be recommended to achieve uniform mass flow and to reduce the adverse effect of powder gliding along the hopper walls.

  9. Force and vortical flow development on pitching wings at high rates

    Science.gov (United States)

    Bernal, Luis; Yu, Huai-Te; Ol, Michael; Granlund, Kenneth

    2014-11-01

    Recent experimental results of pitching flat plate wings are presented. High pitch-rate perching maneuvers are frequently used by birds for feeding and landing. Insects use very fast rotation rates at the end of each flapping stroke, which results in high thrust and precise flight. These wing motions are also of interest for engineered micro air vehicles to achieve semi-autonomous landing by unskilled operators. The wing motion considered is a constant rotation rate pitch motion from 0 to 45 degrees of an aspect-ratio-4 flat-plate wing. The goal is to gain a better understanding of force generation mechanisms and their relationship to two- and three-dimensional vortical flow structures. Leading edge, trailing edge, and tip vortices form with large separated flow regions over the wing, however comparison with linear potential flow theory gives good agreement. The evolution of the leading edge vortex is delayed for pivot axes locations downstream of the leading edge. Large forces at the end of the motion slowly return to the steady state value over more than 30 convective times. The flow in the near wake shows a brief period of vortex shedding and strong three dimensional effects. Two different three-dimensional flow features are observed: A rapid development of three-dimensionality in the core of the leading and trailing edge vortices and a swirl motion in the near wake. However the impact of these three-dimensional flow features on force development is small.

  10. A high sensitivity fiber optic macro-bend based gas flow rate transducer for low flow rates: Theory, working principle, and static calibration

    Science.gov (United States)

    Schena, Emiliano; Saccomandi, Paola; Silvestri, Sergio

    2013-02-01

    A novel fiber optic macro-bend based gas flowmeter for low flow rates is presented. Theoretical analysis of the sensor working principle, design, and static calibration were performed. The measuring system consists of: an optical fiber, a light emitting diode (LED), a Quadrant position sensitive Detector (QD), and an analog electronic circuit for signal processing. The fiber tip undergoes a deflection in the flow, acting like a cantilever. The consequent displacement of light spot center is monitored by the QD generating four unbalanced photocurrents which are function of fiber tip position. The analog electronic circuit processes the photocurrents providing voltage signal proportional to light spot position. A circular target was placed on the fiber in order to increase the sensing surface. Sensor, tested in the measurement range up to 10 l min-1, shows a discrimination threshold of 2 l min-1, extremely low fluid dynamic resistance (0.17 Pa min l-1), and high sensitivity, also at low flow rates (i.e., 33 mV min l-1 up to 4 l min-1 and 98 mV min l-1 from 4 l min-1 up to 10 l min-1). Experimental results agree with the theoretical predictions. The high sensitivity, along with the reduced dimension and negligible pressure drop, makes the proposed transducer suitable for medical applications in neonatal ventilation.

  11. Salivary flow rates among women diagnosed with benign and malignant tumors.

    Science.gov (United States)

    Napeñas, Joel J; Miles, Leslie; Guajardo-Streckfus, Cynthia; Streckfus, Charles F

    2013-01-01

    The purpose of this study was to compare salivary flow rates (SWS) among patients diagnosed with benign and varying malignant solid tumors with the comparison group, prior to the initiation of any treatment. An evaluation of the results found that mean baseline SWS flow rates were higher for healthy patients (1.55 ml/min) when compared to patients diagnosed with benign tumors (1.13 ml/min), breast cancer (1.09 ml/min), and reproductive carcinomas (0.94 ml/min). The overall model (F = 7.76; p flow rates. The results suggest that salivary secretion is lower among both benign and malignant tumor subjects prior to the initiation of treatment. Salivary evaluations of subjects prior to treatment may be useful in identifying individuals at risk for oral complications during chemotherapy. ©2013 Special Care Dentistry Association and Wiley Periodicals, Inc.

  12. Experimental Studies for Determining Gas Flow Rate Accidental Release on Linear Part of Pipeline

    Science.gov (United States)

    Fetisov, V. G.; Nikolaev, A. K.; Lykov, Y. V.

    2017-10-01

    The method of determining the flow rate of gas in the gas-dynamic resistance of a medium gas stream with high linear speed was studied. The reduction of the density of the gas is a result of its expansion. Multiple calculations of gas losses were evaluated. Calculation is set by loss of gas depending on the area of the pipeline damage. A comparative analysis was done. In order to establish a functional empirical dependence of the flow rate on the whole on the parameters of the leakage process, a series of experiments was conducted on a test bench and their processing was carried out. In experiments conducted, the effect of pressure and temperature in the receiver was evaluated, the physical properties of the gas and the diameter of the hole were predetermined by the limits of the amount of the whole flow rate in critical conditions, as well as the critical regime of gas leakage.

  13. Retrograde flow and shear rate acutely impair endothelial function in humans.

    Science.gov (United States)

    Thijssen, Dick H J; Dawson, Ellen A; Tinken, Toni M; Cable, N Timothy; Green, Daniel J

    2009-06-01

    Changes in arterial shear stress induce functional and structural vasculature adaptations. Recent studies indicate that substantial retrograde flow and shear can occur through human conduit arteries. In animals, retrograde shear is associated with atherogenic effects. The aim of this study was to examine the impact of incremental levels of retrograde shear on endothelial function in vivo. On 3 separate days, we examined bilateral brachial artery flow-mediated dilation, an index of NO-mediated endothelial function, in healthy men (24+/-3 years) before and after a 30-minute intervention consisting of cuff inflation to 25, 50, or 75 mm Hg. Cuff inflations resulted in "dose"-dependent increases in retrograde shear rate, compared with the noncuffed arm, within subjects (P<0.001). Flow-mediated dilation in the cuffed arm did not change in response to the 25-mm Hg stimulus but decreased significantly after both the 50- and 75-mm Hg interventions (P<0.05). The decrease in flow-mediated dilation after the 75-mm Hg intervention was significantly larger than that observed after a 50-mm Hg intervention (P=0.03). In the noncuffed arm, no changes in shear rate or flow-mediated dilation were observed. These results demonstrate that an increase in retrograde shear rate induces a dose-dependent attenuation of endothelial function in humans. This finding contributes to our understanding regarding the possible detrimental effects of retrograde shear rate in vivo.

  14. Estimation of Leak Flow Rate during Post-LOCA Using Cascaded Fuzzy Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)

    2016-10-15

    In this study, important parameters such as the break position, size, and leak flow rate of loss of coolant accidents (LOCAs), provide operators with essential information for recovering the cooling capability of the nuclear reactor core, for preventing the reactor core from melting down, and for managing severe accidents effectively. Leak flow rate should consist of break size, differential pressure, temperature, and so on (where differential pressure means difference between internal and external reactor vessel pressure). The leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this paper, a cascaded fuzzy neural network (CFNN) model is appropriately proposed to estimate the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). The CFNN is a data-based model, it requires data to develop and verify itself. Because few actual severe accident data exist, it is essential to obtain the data required in the proposed model using numerical simulations. In this study, a CFNN model was developed to predict the leak flow rate before proceeding to severe LOCAs. The simulations showed that the developed CFNN model accurately predicted the leak flow rate with less error than 0.5%. The CFNN model is much better than FNN model under the same conditions, such as the same fuzzy rules. At the result of comparison, the RMS errors of the CFNN model were reduced by approximately 82 ~ 97% of those of the FNN model.

  15. Comparison of Gravity Flow Rates Between ENFit and Legacy Feeding Tubes.

    Science.gov (United States)

    Mundi, Manpreet S; Duellman, Wanda; Epp, Lisa; Davidson, Jacob; Hurt, Ryan T

    2017-04-01

    Misconnections between enteral supplies and other access devices have led to significant morbidity and mortality. To reduce misconnections, a standard small-bore connector has been developed (International Organization for Standards 80369-8; ENFit). The full impact of transition to this connector is not known, however. Working with major manufacturers and Food and Drug Administration, we obtained ENFit and comparative legacy tubes of variable sizes (low-profile, 14F, 18F, 20F, and 24F balloon gastrostomies). Gravity enteral feeding was simulated with an empty bolus syringe attached to the feeding tube to be tested. The tube was clamped and filled to the 60-mL mark with liquid (water, Jevity 1 Cal, Isosource HN, Isosource 1.5 Cal, Two Cal HN, and Nourish). The clamp was released, and time for formula to leave the syringe was recorded. There was no difference in flow rate between the aggregate legacy and ENFit tubes for the low-profile, 18F, and 20F sizes. The ENFit 14F tubes had a lower flow rate versus the legacy tubes, largely due to the low flow rates seen with the 1 ENFit tube. Similarly, 24F ENFit tubes with some formulas yielded lower flow rates as opposed to legacy. Overall, for the low-profile, 18F, and 20F sizes, the ENFit tubes had similar flow rates when compared with the legacy tubes. For the 14F and 24F sizes, the flow rate of ENFit tubes was significantly lower, which could result in longer EN delivery for patients who are using these tubes to provide gravity feeding.

  16. Co-relationships between glandular salivary flow rates and dental caries.

    Science.gov (United States)

    Diaz de Guillory, Carolina; Schoolfield, John D; Johnson, Dorthea; Yeh, Chih-Ko; Chen, Shuo; Cappelli, David P; Bober-Moken, Irene G; Dang, Howard

    2014-09-01

    This study was designed to evaluate the relationship of age, gender, ethnicity and salivary flow rates on dental caries in an adult population using data collected from the Oral Health San Antonio Longitudinal Study of Aging (OH: SALSA). Saliva is essential to maintain a healthy oral environment and diminished output can result in dental caries. Although gender and age play a role in the quantity of saliva, little is known about the interaction of age, gender and ethnicity on dental caries and salivary flow rates. Data from the 1147 participants in the OH: SALSA were analysed. The dependent variables were the number of teeth with untreated coronal caries, number of teeth with root caries and the number of coronal and root surfaces with untreated caries. The independent variables were stimulated and unstimulated glandular salivary flow rates along with the age, sex and ethnicity (e.g. European or Mexican ancestry) of the participants. Coronal caries experience was greater in younger participants while root surface caries experience was greater in the older participants. Coronal caries was lower in the older age groups while the root caries experience increased. Men had a statistically significant (p flow rates showed no age difference and remained constant with age, whereas the age differences in the unstimulated and stimulated submandibular/sublingual salivary flow rates were significant. The mean number of teeth with coronal and root caries was higher in Mexican-Americans than in European-Americans. Over one-fourth of the adults between the ages of 60 and 79 have untreated root caries over one-third having untreated coronal caries. Lower salivary flow rates play a significant role in both the number of teeth and the number of surfaces developing caries in these adults. Women and individuals of European-American ancestry experience less caries. © 2013 The Gerodontology Society and John Wiley & Sons A/S.

  17. Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates.

    Science.gov (United States)

    Longest, P Worth; Tian, Geng; Khajeh-Hosseini-Dalasm, Navvab; Hindle, Michael

    2016-12-01

    The objective of this study was to compare aerosol deposition predictions of a new whole-airway CFD model with available in vivo data for a dry powder inhaler (DPI) considered across multiple inhalation waveforms, which affect both the particle size distribution (PSD) and particle deposition. The Novolizer DPI with a budesonide formulation was selected based on the availability of 2D gamma scintigraphy data in humans for three different well-defined inhalation waveforms. Initial in vitro cascade impaction experiments were conducted at multiple constant (square-wave) particle sizing flow rates to characterize PSDs. The whole-airway CFD modeling approach implemented the experimentally determined PSDs at the point of aerosol formation in the inhaler. Complete characteristic airway geometries for an adult were evaluated through the lobar bronchi, followed by stochastic individual pathway (SIP) approximations through the tracheobronchial region and new acinar moving wall models of the alveolar region. It was determined that the PSD used for each inhalation waveform should be based on a constant particle sizing flow rate equal to the average of the inhalation waveform's peak inspiratory flow rate (PIFR) and mean flow rate [i.e., AVG(PIFR, Mean)]. Using this technique, agreement with the in vivo data was acceptable with <15% relative differences averaged across the three regions considered for all inhalation waveforms. Defining a peripheral to central deposition ratio (P/C) based on alveolar and tracheobronchial compartments, respectively, large flow-rate-dependent differences were observed, which were not evident in the original 2D in vivo data. The agreement between the CFD predictions and in vivo data was dependent on accurate initial estimates of the PSD, emphasizing the need for a combination in vitro-in silico approach. Furthermore, use of the AVG(PIFR, Mean) value was identified as a potentially useful method for characterizing a DPI aerosol at a constant flow rate.

  18. Effects of Chewing Different Flavored Gums on Salivary Flow Rate and pH

    OpenAIRE

    Karami Nogourani, Maryam; Janghorbani, Mohsen; Kowsari Isfahan, Raha; Hosseini Beheshti, Mozhgan

    2012-01-01

    Chewing gum increases salivary flow rate (SFR) and pH, but differences in preferences of gum flavor may influence SFR and pH. The aim of this paper was to assess the effect of five different flavors of sucrose-free chewing gum on the salivary flow rate and pH in healthy dental students in Isfahan, Iran. Fifteen (7 men and 8 women) healthy dental student volunteers collected unstimulated saliva and then chewed one of five flavored gums for 6 min. The whole saliva was collected and assessed for...

  19. The rate dependence of the saturation flow stress of Cu and 1100 Al

    Energy Technology Data Exchange (ETDEWEB)

    Preston, D.L.; Tonks, D.L.; Wallace, D.C.

    1991-01-01

    The strain-rate dependence of the saturation flow stress of OFHC Cu and 1100 Al from 10{sup {minus}3}s{sup {minus}1} to nearly to 10{sup 12}s{sup {minus}1} is examined. The flow stress above 10{sup 9}s{sup {minus}1} is estimated using Wallace's theory of overdriven shocks in metals. A transition to the power-law behavior {Psi} {approximately} {tau}{sub s}{sup 5} occurs at a strain rate of order 10{sup 5}s{sup {minus}1}. 10 refs., 2 figs.

  20. Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

    DEFF Research Database (Denmark)

    Svendsen, J H; Sheikh, S P; Jørgensen, J

    1990-01-01

    The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY-like immunoreac......The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY...

  1. Peak expiratory flow rates produced with the Laerdal and Mapleson-C bagging circuits.

    Science.gov (United States)

    Jones, A; Hutchinson, R; Lin, E; Oh, T

    1992-01-01

    This study compared the peak expiratory flow rates (PEFR) at different inspiratory pause pressures (IPP) produced by the Mapleson-C circuit and the Laerdal self-inflating resuscitator. The difference in PEFR produced by the two circuits was significantly different at the lowest and the highest IPP studied (I3 and 38cm H20). The greatest differences in the mean expiratory flow rates produced was, however, only 0.07 litre sec(-7). The authors suggest that the choice of bagging circuit should depend on the experience and familiarity of the therapist with the circuit. Copyright © 1992 Australian Physiotherapy Association. Published by . All rights reserved.

  2. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  3. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    Science.gov (United States)

    Villagómez-Hoyos, Carlos A.; Stuart, Matthias B.; Bechsgaard, Thor; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow angle in the ROI was 86.22° +/- 6.66° with a true flow angle of 90°. A relative velocity bias of -39% with a standard deviation of 13% was found. In-vivo acquisitions show complex flow patterns in the heart. In the aortic valve view, blood is seen exiting the left ventricle cavity through the aortic valve into the aorta during the systolic phase of the cardiac cycle. In the left ventricle view, blood flow is seen entering the left ventricle cavity through the mitral valve and splitting in two ways when approximating the left ventricle wall. The work presents 2-D velocity estimates on the heart from a non-invasive transthoracic scan. The ability of the method detecting flow regardless of the beam angle could potentially reveal a more complete view of the flow patterns presented on the heart.

  4. Meta-Analysis of Salivary Flow Rates in Young and Older Adults.

    Science.gov (United States)

    Affoo, Rebecca H; Foley, Norine; Garrick, Rushlee; Siqueira, Walter L; Martin, Ruth E

    2015-10-01

    To determine whether salivary flow decreases as a function of aging. Meta-analysis. Literature review. Individuals aged 18 and older reported to be free of major systemic disease. Relevant studies were identified through a literature search of several databases, from their inception to June 2013. Studies were included if saliva had been collected on at least one occasion in subjects aged 18 and older and if the data were presented in a manner that enabled comparisons of younger and older participants. Differences in salivary flow rates between age groups were calculated for each salivary source and condition and reported as standardized mean differences (SMDs), standard errors (SEs) and 95% confidence intervals (CIs). The results were pooled using a random effects model. A separate analysis examining medication use was also conducted. Forty-seven studies were included. Whole (SMD = 0.551, SE = 0.056, 95% CI = 0.423-0.678, P flow rates were reduced significantly in older participants and in unstimulated and stimulated conditions. In contrast, parotid and minor gland salivary flow rates were not significantly reduced with increasing age. Additionally, unstimulated and stimulated SMSL, and unstimulated whole salivary flow rates were significantly lower in older adults, regardless of medication usage. The aging process is associated with reduced salivary flow in a salivary-gland-specific manner; this reduction in salivary flow cannot be explained on the basis of medications. These findings have important clinical implications for maintaining optimal oral health in older adults. © 2015, Copyright the Authors Journal compilation © 2015, The American Geriatrics Society.

  5. A non-contact optical procedure for precise measurement of respiration rate and flow

    Science.gov (United States)

    Scalise, Lorenzo; Marchionni, Paolo; Ercoli, Ilaria

    2010-04-01

    The use of standard instrumentation for the assessment of the respiration rate as of flow is an important goal in medicine. Spirometers, textile-based capacitive sensors or photopletismography are standard contact instrumentations used for such aim; the main drawback in the use of such instrumentations is the necessity to have a direct contact of the instrument with the patient. In this paper, we present an optical no-contact method for monitoring of both the respiration rate and flow. This method is based on the measurement of external chest wall movement by a laser Doppler vibrometer. The measurement procedure has already been demonstrated to be extremely well performing for what concern the monitoring of the cardiac activity. The proposed method can be operated at a distance of 1.5 m, on different point of the patient thoracic and abdominal area. We have monitored respiration rate and flow on 8 patients with a spirometer and simultaneously with the proposed noncontact measurement procedure. Bland-Altman analysis of the respiration rate measured with both instruments demonstrate a mean error on the determination of the respiration rate of < 1% and of the < 4% for the instantaneous flow. We also report a study on the optimal position on the thoracic area based on quality of the signal measured on the same population of subject.

  6. The Effect of Insulating Blood Warmer Output Tubing on the Temperature of Packed Red Blood Cells at Low Flow Rates

    Science.gov (United States)

    1989-01-01

    blood cells at the point of patient entry at low flow rates . Utilizing a surgical suite, every attempt was made to replicate a true surgical setting...Flow control pumps were used to regulate flow rates of 300, 600, and 900 milliliters per hour (ml/hr) through Fenwall Laboratories blood warming coils

  7. Expanding the range for predicting critical flow rates of gas wells producing from normally pressured waterdrive reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Upchurch, E.R. (Thums Long Beach Co. (US))

    1989-08-01

    The critical flow rate of a gas well is the minimum flow rate required to prevent accumulation of liquids in the tubing. Theoretical models currently available for estimating critical flow rates are restricted to wells with water/gas ratios less than 150bbl/MMcf (0.84 X 10/sup -3/ m/sup 3//m/sup 3/). For wells producing at higher water/gas ratios from normally pressured waterdrive reservoirs, a method of estimating critical flow rates is derived through use of an empirical multiphase-flow correlation.

  8. Determination of flow rates of oil, water and gas in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Roach, G.J.; Watt, J.S.; Zastawny, H.W. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lucas Heights, NSW (Australia). Div. of Mineral Physics

    1993-12-31

    This paper describes a multiphase flow meter developed by CSIRO for determining of the flow rates of oil, water and gas in high pressure pipelines, and the results of a trial of this flow meter on an offshore oil platform. Two gamma-ray transmission gauges are mounted about a pipeline carrying the full flow of oil, water and gas. The flow rates are determined by combining single energy gamma-ray transmission measurements which determine the mass per unit area of fluids in the gamma-ray beam as a function of time, dual energy gamma-ray transmission (DUET) which determine the approximate mass fraction of oil in the liquids, cross-correlation of gamma-ray transmission measurements, with one gauge upstream of the other, which determines flow velocity, pressure and temperature measurements, and knowledge of the specific gravities of oil and (salt) water, and solubility of the gas in the liquids, all as a function of pressure and temperature. 3 figs.

  9. Research on Gas-liquid Flow Rate Optimization in Foam Drilling

    Science.gov (United States)

    Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

    2010-03-01

    With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

  10. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    Science.gov (United States)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  11. Cerberus Fossae and Elysium Planitia Lavas, Mars: Source Vents, Flow Rates, Edifice Styles and Water Interactions

    Science.gov (United States)

    Sakimoto, S. E. H.; Gregg, T. K. P.

    2004-01-01

    The Cerberus Fossae and Elysium Planitia regions have been suggested as some of the youngest martian surfaces since the Viking mission, although there was doubt whether the origins were predominantly volcanic or fluvial. The Mars Global Surveyor and Mars Odyssey Missions have shown that the region is certainly young in terms of the topographic preservation and the youthful crater counts (e.g. in the tens to a few hundred million yrs.). Numerous authors have shown that fluvial and volcanic features share common flow paths and vent systems, and that there is evidence for some interaction between the lava flows and underlying volatiles as well as the use by lavas and water of the same vent system. Given the youthful age and possible water-volcanism interaction environment, we'd like constraints on water and volcanic flux rates and interactions. Here, we model ranges of volcanic flow rates where we can well-constrain them, and consider the modest flow rate results results in context with local eruption styles, and track vent locations, edifice volumes, and flow sources and data.

  12. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H

    1991-01-01

    Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage uni.......0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.......Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...

  13. Rapid mapping of volumetric errors

    Energy Technology Data Exchange (ETDEWEB)

    Krulewich, D.; Hale, L.; Yordy, D.

    1995-09-13

    This paper describes a relatively inexpensive, fast, and easy to execute approach to mapping the volumetric errors of a machine tool, coordinate measuring machine, or robot. An error map is used to characterize a machine or to improve its accuracy by compensating for the systematic errors. The method consists of three steps: (1) modeling the relationship between the volumetric error and the current state of the machine; (2) acquiring error data based on length measurements throughout the work volume; and (3) optimizing the model to the particular machine.

  14. The Effect of the Volume Flow rate on the Efficiency of a Solar Collector

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

    rates. Theoretically, a simplified model of the solar collector panel is built by means of the CFD (Computational Fluid Dynamics) code Fluent, where the geometry of the collector panel except the casing is fully modeled. Both lateral and longitudinal heat conduction in the absorber fins, the heat...... transfer from the absorber to the solar collector fluid and the heat loss from the absorber are considered. Flow and temperature distribution in the collector panel are investigated with buoyancy effect. Measurements are carried out with the solar collector panel. Collector efficiencies are measured......The flow distribution inside a collector panel with an area of 12.5 m² and with 16 parallel connected horizontal fins and the effect of the flow nonuniformity on the risk of boiling and on the collector efficiency have been theoretically and experimentally investigated for different volume flow...

  15. Syringe-pump-induced fluctuation in all-aqueous microfluidic system implications for flow rate accuracy.

    Science.gov (United States)

    Li, Zida; Mak, Sze Yi; Sauret, Alban; Shum, Ho Cheung

    2014-02-21

    We report a new method to display the minute fluctuations induced by syringe pumps on microfluidic flows by using a liquid-liquid system with an ultralow interfacial tension. We demonstrate that the stepper motor inside the pump is a source of fluctuations in microfluidic flows by comparing the frequencies of the ripples observed at the interface to that of the pulsation of the stepper motor. We also quantify the fluctuations induced at different flow rates, using syringes of different diameters, and using different syringe pumps with different advancing distances per step. Our work provides a way to predict the frequency of the fluctuation that the driving syringe pump induces on a microfluidic system and suggests that syringe pumps can be a source of fluctuations in microfluidic flows, thus contributing to the polydispersity of the resulting droplets.

  16. Review of flow rate estimates of the Deepwater Horizon oil spill

    Science.gov (United States)

    McNutt, Marcia K.; Camilli, Rich; Crone, Timothy J.; Guthrie, George D.; Hsieh, Paul A.; Ryerson, Thomas B.; Savas, Omer; Shaffer, Frank

    2012-01-01

    The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ~50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ~5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.

  17. Flow perfusion rate modulates cell deposition onto scaffold substrate during cell seeding.

    Science.gov (United States)

    Campos Marín, A; Brunelli, M; Lacroix, D

    2017-11-29

    The combination of perfusion bioreactors with porous scaffolds is beneficial for the transport of cells during cell seeding. Nonetheless, the fact that cells penetrate into the scaffold pores does not necessarily imply the interception of cells with scaffold substrate and cell attachment. An in vitro perfusion system was built to relate the selected flow rate with seeding efficiency. However, the in vitro model does not elucidate how the flow rate affects the transport and deposition of cells onto the scaffold. Thus, a computational model was developed mimicking in vitro conditions to identify the mechanisms that bring cells to the scaffold from suspension flow. Static and dynamic cell seeding configurations were investigated. In static seeding, cells sediment due to gravity until they encounter the first obstacle. In dynamic seeding, 12, 120 and 600 [Formula: see text] flow rates were explored under the presence or the absence of gravity. Gravity and secondary flow were found to be key factors for cell deposition. In vitro and in silico seeding efficiencies are in the same order of magnitude and follow the same trend with the effect of fluid flow; static seeding results in higher efficiency than dynamic perfusion although irregular spatial distribution of cells was found. In dynamic seeding, 120 [Formula: see text] provided the best seeding results. Nevertheless, the perfusion approach reports low efficiencies for the scaffold used in this study which leads to cell waste and low density of cells inside the scaffold. This study suggests gravity and secondary flow as the driving mechanisms for cell-scaffold deposition. In addition, the present in silico model can help to optimize hydrodynamic-based seeding strategies prior to experiments and enhance cell seeding efficiency.

  18. A Simple Analytical Model of Coupled Single Flow Channel over Porous Electrode in Vanadium Redox Flow Battery with Serpentine Flow Channel

    CERN Document Server

    Ke, Xinyou; Prahl, Joseph M; Savinell, Robert F

    2016-01-01

    A simple analytical model of a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer) is proposed. This analytical model is derived from Navier-Stokes motion in the flow channel and Darcy-Brinkman model in the porous layer. The continuities of flow velocity and normal stress are applied at the interface between the flow channel and the porous layer. The effects of the inlet volumetric flow rate, thickness of the flow channel and thickness of a typical carbon fiber paper porous layer on the volumetric flow rate within this porous layer are studied. The maximum current density based on the electrolyte volumetric flow rate is predicted, and found to be consistent with reported numerical simulation. It is found that, for a mean inlet flow velocity of 33.3 cm s-1, the analytical maximum current density is estimated to be 377 mA cm-2, which compares favorably with experimental result reported by others of ~400 mA cm-2.

  19. Effects of Purge-Flow Rate on Microbubble Capture in Radial Arterial-Line Filters

    Science.gov (United States)

    Herbst, Daniel P.

    2016-01-01

    Abstract: The process of microbubble filtration from blood is complex and highly dependent on the forces of flow and buoyancy. To protect the patient from air emboli, arterial-line filters commonly use a micropore screen, a large volume housing with purpose-built shape, and a purge port to trap, separate, and remove circulating microbubbles. Although it has been proposed that an insufficient buoyancy force renders the purge port ineffective at removing microbubbles smaller than 500 μm, this research attempts to investigate the purge flow of an arterial-line filter to better understand the microbubble removal function in a typical radial filter design. As its primary objective, the study aims to determine the effect of purge-flow rate on bubble capture using air bolus injections from a syringe pump with 22-gauge needle and Doppler ultrasound bubble detection. The measureable bubble size generated in the test circuit ranged between 30 and 500 μm, while purge flow was varied between .1 and .5 L/min for testing. Statistical analysis of the test data was handled using a repeated measures design with significance set at p bubble counts, but the effect of purge-flow rate on bubble capture decreased as bubble size increased. Results also showed that purge flow from the test filter was capable of capturing all bubble sizes being generated over the entire flow range tested, and confirms utility of the purge port in removing microbubbles smaller than 500 μm. By analyzing bubble counts in the purge flow of a typical radial-filter design, this study demonstrates that currently available micropore filter technology is capable of removing the size range of bubbles that commonly pass through modern pump-oxygenator systems and should continue to be considered during extracorporeal circulation as a measure to improve patient safety. PMID:27729703

  20. Effects of Purge-Flow Rate on Microbubble Capture in Radial Arterial-Line Filters.

    Science.gov (United States)

    Herbst, Daniel P

    2016-09-01

    The process of microbubble filtration from blood is complex and highly dependent on the forces of flow and buoyancy. To protect the patient from air emboli, arterial-line filters commonly use a micropore screen, a large volume housing with purpose-built shape, and a purge port to trap, separate, and remove circulating microbubbles. Although it has been proposed that an insufficient buoyancy force renders the purge port ineffective at removing microbubbles smaller than 500 μm, this research attempts to investigate the purge flow of an arterial-line filter to better understand the microbubble removal function in a typical radial filter design. As its primary objective, the study aims to determine the effect of purge-flow rate on bubble capture using air bolus injections from a syringe pump with 22-gauge needle and Doppler ultrasound bubble detection. The measureable bubble size generated in the test circuit ranged between 30 and 500 μm, while purge flow was varied between .1 and .5 L/min for testing. Statistical analysis of the test data was handled using a repeated measures design with significance set at p bubble counts, but the effect of purge-flow rate on bubble capture decreased as bubble size increased. Results also showed that purge flow from the test filter was capable of capturing all bubble sizes being generated over the entire flow range tested, and confirms utility of the purge port in removing microbubbles smaller than 500 μm. By analyzing bubble counts in the purge flow of a typical radial-filter design, this study demonstrates that currently available micropore filter technology is capable of removing the size range of bubbles that commonly pass through modern pump-oxygenator systems and should continue to be considered during extracorporeal circulation as a measure to improve patient safety.

  1. Development of a low flow meter for measuring gas production in bioreactors

    Science.gov (United States)

    Accurate measurement of gas production from biological processes is important in many laboratory experiments. A gas flow rate measurement system, consisting of an embedded controller operating three gas meters, was developed to measure volumetric flows between 0 and 8 ml min-1 (1 atm, 273.15 K). The...

  2. Energy policy act transportation study: Interim report on natural gas flows and rates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-17

    This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of natural gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.

  3. Evaluation of Peak Expiratory Flow rates (PEFR) of Workers in a ...

    African Journals Online (AJOL)

    Method: In this descriptive cross-sectional study, 105 workers of a cement company who presented for the annual fitness to work exercise were sampled and had their peak expiratory flow rates measured using a spirometer. Data were also collected using structured interviewer-administered questionnaires and a walk ...

  4. Flow rate through microfilters: Influence of the pore size distribution, hydrodynamic interactions, wall slip, and inertia

    DEFF Research Database (Denmark)

    Jensen, Kaare Hartvig; Valente, Andre X. C. N.; Stone, Howard A.

    2014-01-01

    to obtain an analytical formula for the pressure drop across the microfilter versus the flow rate that accounts for the non-uniform distribution of pore sizes, the hydrodynamic interactions between the pores given their layout pattern, and wall slip. Further, we discuss inertial effects and their order...

  5. Influence of nitrogen flow rates on materials properties of CrNx films ...

    Indian Academy of Sciences (India)

    Abstract. Chromium nitride (CrN) hard thin films were deposited on different substrates by reactive direct current. (d.c.) magnetron sputtering with different nitrogen flow rates. The X-ray diffraction patterns showed mixed Cr2N and CrN phases. The variations in structural parameters are discussed. The grain size increased ...

  6. Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Kristensen, J K

    1991-01-01

    The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12-20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium...

  7. Fabric inlet stratifiers for solar tanks with different volume flow rates

    DEFF Research Database (Denmark)

    Andersen, Elsa; Furbo, Simon

    2006-01-01

    in the centre of a glass tank (400 x 400 x 900 mm). The forced volume flow rate is in the range of 6 – 10 l/min, and water enters the stratification pipe from the bottom of the tank. The thermal behaviour of the stratification pipes is investigated for different realistic operation conditions...

  8. Lower urinary tract symptoms and urinary flow rates in female patients with hyperthyroidism.

    Science.gov (United States)

    Ho, Chen-Hsun; Chang, Tien-Chun; Guo, Ya-Jun; Chen, Shyh-Chyan; Yu, Hong-Jeng; Huang, Kuo-How

    2011-01-01

    To investigate lower urinary tract symptoms (LUTS) and voiding function in a cohort of hyperthyroid women. The autonomic nervous system (ANS) imbalance has been thought to cause LUTS in hyperthyroidism. Between January 2008 and December 2008, 65 newly diagnosed, untreated female hyperthyroid patients were enrolled in this study. Another 62 age-matched healthy women were enrolled as a control group. Demographics, LUTS, urinary flow rates, hyperthyroid symptoms, and serum levels of thyroid hormones were recorded before and after the medical treatment for hyperthyroidism. Compared with the control group, the hyperthyroid patients had a higher mean symptom score of frequency (1.15 ± 1.75 vs 0.31 ± 1.05, P = .01), incomplete emptying (0.91 ± 1.47 vs 0.29 ± 1.12, P = .02), straining (1.05 ± 0.85 vs 0.27 ± 0.51, P flow rates improved significantly. The severity of LUTS was associated with neither serum levels of thyroid hormone nor other hyperthyroid symptoms. Hyperthyroid women have worse LUTS and lower peak flow rates than healthy controls. However, the severity of LUTS is only mild (IPSS flow rates improve after the treatment for hyperthyroidism. The exact mechanisms of LUTS and/or lower urinary tract dysfunction in hyperthyroidism require further investigation. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Flow rates and pressure profiles for one to four axially alined Borda inlets

    Science.gov (United States)

    Hendricks, R. C.; Stetz, T. T.

    1984-01-01

    Choked flow rate and pressure profile data were taken on sequential, axially alined inlets of the Borda type. The configurations consisted of two to four inlets spaced 0.8 and 30 diameters apart. At a spacing of 30 diameters the reduced flow rate appeared to follow the simple empirical relation G sub r/G sub r,1=N(-b), where G sub r,1 is the reduced flow rate for a single inlet; N is the number of inlets; and b, which is weakly temperature dependent, is approximately 0.4. The relation is in reasonable agreement with an analysis of the N-inlet configuration. At a spacing of 30 diameters the pressure profiles dropped sharply at the entrance and partially recovered within each inlet somewhat independently of N. Jetting through the last Borda was common at low temperatures. At a spacing of 0.8 diameter fluid jetting was prevalent at low temperatures for each configuration studied and flow rates were the same as that for a single inlet.

  10. Glucose Pump Test can be Used to Measure Blood Flow Rate of ...

    African Journals Online (AJOL)

    2018-02-07

    Feb 7, 2018 ... Purpose: In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies.

  11. Influence of nitrogen flow rates on materials properties of CrNx films ...

    Indian Academy of Sciences (India)

    Chromium nitride (CrN) hard thin films were deposited on different substrates by reactive direct current (d.c.) magnetron sputtering with different nitrogen flow rates. The X-ray diffraction patterns showed mixed Cr2N and CrN phases. The variations in structural parameters are discussed. The grain size increased with ...

  12. Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B

    1991-01-01

    Subcutaneous adipose tissue blood flow rate was measured in the lower leg of 22 normal human subjects over 12- to 20-h ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used. The tracer depot was applied on the medial aspect...

  13. Performance and radial distribution profiles of a variable flow rate sprinkler developed for precision irrigation

    Directory of Open Access Journals (Sweden)

    Robson André Armindo

    2012-04-01

    Full Text Available Variable rate sprinklers (VRS have been developed to promote localized water application of irrigated areas. In Precision Irrigation, VRS permits better control of flow adjustment and, at the same time, provides satisfactory radial distribution profiles for various pressures and flow rates are really necessary. The objective of this work was to evaluate the performance and radial distribution profiles of a developed VRS which varies the nozzle cross sectional area by moving a pin in or out using a stepper motor. Field tests were performed under different conditions of service pressure, rotation angles imposed on the pin and flow rate which resulted in maximal water throw radiuses ranging from 7.30 to 10.38 m. In the experiments in which the service pressure remained constant, the maximal throw radius varied from 7.96 to 8.91 m. Averages were used of repetitions performed under conditions without wind or with winds less than 1.3 m s-1. The VRS with the four stream deflector resulted in greater water application throw radius compared to the six stream deflector. However, the six stream deflector had greater precipitation intensities, as well as better distribution. Thus, selection of the deflector to be utilized should be based on project requirements, respecting the difference in the obtained results. With a small opening of the nozzle, the VRS produced small water droplets that visually presented applicability for foliar chemigation. Regarding the comparison between the estimated and observed flow rates, the stepper motor produced excellent results.

  14. PROGRESSIVE MUSCLE RELAXATION INCREASE PEAK EXPIRATORY FLOW RATE ON CHRONIC OBSTRUCTIVE PULMONARY DISEASE PATIENTS

    Directory of Open Access Journals (Sweden)

    Tintin Sukartini

    2017-07-01

    Full Text Available Introduction: Limited progressive air flow in Chronic Obstructive Pulmonary Disease (COPD can caused by small airway disease (bronchiolitis obstructive and loss of elasticity of the lung (emphysema. Further it can be decreasing the quality of life in COPD patients because dyspnea and uncomfortable in activity. Progressive muscle relaxation (PMR is one of the relaxation technique that can repair pulmonary ventilation by decreasing chronic constriction of the respiratory muscles. The objective of this study was to analyze the effect of progressive muscle relaxation on raised peak expiratory flow rate (PEFR. Method: A pre-experimental one group pre-post test design was used in this study. Population was all of the COPD patients at Pulmonary Specialist Polyclinic Dr Mohamad Soewandhie Surabaya. There were 8 respondents taken by using purposive sampling. PEFR was counted by using peak flow meter every six day. Data were analyzed by using Paired t-Test with significance level  p≤0.05. Result: The result showed that PMR had significance level on increasing of PEFR (p=0.012. Discussion: It can be concluded that PMR has an effect on raise PEFR. Further studies are recommended to measure the effect of PMR on respiratory rate (RR, heart rate (HR subjective dyspnoe symptoms, forced expiration volume on the first minute (FEV1 and mid maximum flow rate (MMFR in COPD patients.

  15. The control of self-propelled microjets inside a microchannel with time-varying flow rates

    NARCIS (Netherlands)

    Khalil, I.S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver S.; Misra, Sarthak

    We demonstrate the closed-loop motion control of self-propelled microjets inside a fluidic microchannel. The motion control of the microjets is achieved in hydrogen peroxide solution with time-varying flow rates, under the influence of the controlled magnetic fields and the self-propulsion force.

  16. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  17. Sympathetic nervous system activation, arterial shear rate, and flow-mediated dilation.

    NARCIS (Netherlands)

    Thijssen, D.H.J.; Atkinson, C.L.; Ono, K.; Sprung, V.S.; Spence, A.L.; Pugh, C.J.; Green, D.J.

    2014-01-01

    The aim of this study was to examine the contribution of arterial shear to changes in flow-mediated dilation (FMD) during sympathetic nervous system (SNS) activation in healthy humans. Ten healthy men reported to our laboratory four times. Bilateral FMD, shear rate (SR), and catecholamines were

  18. Determination of vibration frequency depending on abrasive mass flow rate during abrasive water jet cutting

    Czech Academy of Sciences Publication Activity Database

    Hreha, P.; Radvanská, A.; Hloch, Sergej; Peržel, V.; Krolczyk, G.; Monková, K.

    2014-01-01

    Roč. 77, 1-4 (2014), s. 763-774 ISSN 0268-3768 Institutional support: RVO:68145535 Keywords : Abrasive water jet * Abrasive mass flow rate * Vibration Subject RIV: JQ - Machines ; Tools Impact factor: 1.458, year: 2014 http://link.springer.com/article/10.1007%2Fs00170-014-6497-9#page-1

  19. Glucose Pump Test can be Used to Measure Blood Flow Rate of ...

    African Journals Online (AJOL)

    Purpose: In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies. However ...

  20. Saliva flow rate, buffer capacity, and pH of autistic individuals.

    Science.gov (United States)

    Bassoukou, Ivy Haralambos; Nicolau, José; dos Santos, Maria Teresa

    2009-03-01

    The objective of the study was to evaluate saliva flow rate, buffer capacity, pH levels, and dental caries experience (DCE) in autistic individuals, comparing the results with a control group (CG). The study was performed on 25 noninstitutionalized autistic boys, divided in two groups. G1 composed of ten children, ages 3-8. G2 composed of 15 adolescents ages 9-13. The CG was composed of 25 healthy boys, randomly selected and also divided in two groups: CG3 composed of 14 children ages 4-8, and CG4 composed of 11 adolescents ages 9-14. Whole saliva was collected under slight suction, and pH and buffer capacity were determined using a digital pHmeter. Buffer capacity was measured by titration using 0.01 N HCl, and the flow rate expressed in ml/min, and the DCE was expressed by decayed, missing, and filled teeth (permanent dentition [DMFT] and primary dentition [dmft]). Data were plotted and submitted to nonparametric (Kruskal-Wallis) and parametric (Student's t test) statistical tests with a significance level less than 0.05. When comparing G1 and CG3, groups did not differ in flow rate, pH levels, buffer capacity, or DMFT. Groups G2 and CG4 differ significantly in pH (p = 0.007) and pHi = 7.0 (p = 0.001), with lower scores for G2. In autistic individuals aged 3-8 and 9-13, medicated or not, there was no significant statistical difference in flow rate, pH, and buffer capacity. The comparison of DCE among autistic children and CG children with deciduous (dmft) and mixed/permanent decayed, missing, and filled teeth (DMFT) did not show statistical difference (p = 0.743). Data suggest that autistic individuals have neither a higher flow rate nor a better buffer capacity. Similar DCE was observed in both groups studied.

  1. Prediction of Leak Flow Rate Using FNNs in Severe LOCA Circumstances

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong; Yoo, Kwae Hwan; Kim, Ju Hyun; Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of); Hur, Seop; Kim, Chang Hwoi [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Leak flow rate is a function of break size, differential pressure ( i.e., difference between internal and external reactor vessel pressure), temperature, and so on. Specially, the leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this study, a fuzzy neural network (FNN) model is proposed to predict the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). Since FNN is a data-based model, it requires data to develop and verify itself. However, because actual severe accident data do not exist to the best of our knowledge, it is essential to obtain the data required in the proposed model using numerical simulations. These data were obtained by simulating severe accident scenarios for the optimized power reactor 1000 (OPR 1000) using MAAP4 code. In this study, FNN model was developed to predict the leak flow rate in severe post-LOCA circumstances.. The training data were selected from among all the acquired data using an SC method to train the proposed FNN model with more informative data. The developed FNN model predicted the leak flow rate using the time elapsed after reactor shutdown and the predicted break size, and its validity was verified in the basis of the simulation data of OPR1000 using MAAP4 code.

  2. The association between coronary flow rate and impaired heart rate recovery in patients with metabolic syndrome: A preliminary report.

    Science.gov (United States)

    Alihanoglu, Yusuf I; Kilic, I Dogu; Evrengul, Harun; Yildiz, Bekir S; Alur, Ihsan; Uludag, Burcu; Kuru, Omur; Taskoylu, Ozgur; Kaftan, Havane Asuman

    2014-01-01

    The aim of this study is to evaluate heart rate recovery (HRR) and association between coronary flow rate and HRR in patients with metabolic syndrome (MS) who had morphologically normal coronary angiogram. Study population included 43 patients with MS and 37 control subjects without MS. All patients were selected from individuals who had recently undergone coronary angiography in our hospital and were diagnosed as having angiographically normal coronary arteries. Exercise stress test results obtained prior to coronary angiography were evaluated for calculating HRR and other parameters. In addition, coronary flow was objectively evaluated for each major coronary artery in each subject using TIMI frame count method. All HRR values calculated were detected significantly lower in MS group compared to controls (HRR first: 32 ± 9 vs. 37 ± 10; p = 0.01, second: 46 ± 11 vs. 52 ± 11; p = 0.03, third: 51 ± 12 vs. 59 ± 12; p = 0.00, fourth: 54 ± 13 vs. 61 ± 2; p = 0.02). TIMI frame counts for each major epicardial coronary artery and mean TIMI frame count were also found to be significantly higher in MS group compared to controls (left anterior descending artery:51 ± 24 vs. 39 ± 15; p = 0.009, left circumflex artery: 32 ± 11 vs. 24 ± 7; p = 0.001, right coronary artery: 33 ± 14 vs. 24 ± 10; p = 0.003, mean TIMI frame count: 38 ± 15 vs. 29 ± 9;p = 0.002). Additionally, significant negative correlations were also detected between HRR first minute and coronary TIMI frame count values in patients with MS. None of MS parameters did not affect HRR values, however mean TIMI frame count independently associated with HRR first minute (p = 0.04) in patients with MS. Impaired coronary blood flow occurring in MS might be a clue of autonomic dysfunction in addition to previously known endothelial dysfunction.

  3. Influence of peak inspiratory flow rates and pressure drops on inhalation performance of dry powder inhalers.

    Science.gov (United States)

    Hira, Daiki; Okuda, Tomoyuki; Ichihashi, Mika; Mizutani, Ayano; Ishizeki, Kazunori; Okada, Toyoko; Okamoto, Hirokazu

    2012-01-01

    The aim of this study was to reveal the relationship between human inspiratory flow patterns and the concomitant drops in pressure in different inhalation devices, and the influence of the devices on inhalation performance. As a model formulation for inhalers, a physically mixed dry powder composed of salbutamol sulfate and coarse lactose monohydrate was selected. The drops in pressure at 28.3 L/min of three inhalation devices, Single-type, Dual-type, and Reverse-type, was 1.0, 5.1, and 8.7 kPa, respectively. Measurements of human inspiratory patterns revealed that although the least resistant device (Single) had large inter- and intra-individual variation of peak flow rate (PFR), the coefficients of variation of PFR of the three devices were almost the same. In tests with a human inspiratory flow simulator in vitro, inhalation performance was higher, but the variation in inhalation performance in the range of human flow patterns was wider, for the more resistant device. To minimize the intra- and inter-individual variation in inhalation performance for the model formulation in this study, a formulation design that allows active pharmaceutical ingredient to detach from the carrier with a lower inhalation flow rate is needed.

  4. Effect of solar chimney inclination angle on space flow pattern and ventilation rate

    Energy Technology Data Exchange (ETDEWEB)

    Bassiouny, Ramadan; Korah, Nader S.A. [Department of Mechanical Power Engineering and Energy, Minia University, Minia 61111 (Egypt)

    2009-02-15

    The solar chimney is a simple and practical idea that is applied to enhance space natural ventilation. The chimney could be vertical or inclined. The chimney inclination angle is an important parameter that greatly affects space flow pattern and ventilation rate. In the present study, the effect of chimney inclination angle on air change per hour and indoor flow pattern was numerically and analytically investigated. A numerical simulation using Ansys, a FEM-based code, was used to predict flow pattern. Then the results were compared with published experimental measurements. A FORTRAN program was developed to iteratively solve the mathematical model that was obtained through an overall energy balance on the solar chimney. The analytical results showed that an optimum air flow rate value was achieved when the chimney inclination is between 45 and 70 for latitude of 28.4 . The numerically predicted flow pattern inside the space supports this finding. Moreover, in the present study a correlation to predict the air change per hour was developed. The correlation was tested within a solar intensity greater than or equal to 500 W/m{sup 2}, and chimney width from 0.1 m to 0.35 m for different inclination angles with acceptable values. (author)

  5. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Bechsgaard, Thor

    2016-01-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view...... (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter...... vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow anglein the ROI was 86.22◦ ± 6.66◦ with a true flow angle of 90◦. A relative velocity bias of −39% with a standard deviation of 13% was found...

  6. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  7. Effect of different carrier gases and their flow rates on the growth of carbon nanotubes

    Science.gov (United States)

    Tewari, Aarti; Sharma, Suresh C.

    2015-04-01

    The present paper examines the effect of different carrier gases and their flow rates on the growth of carbon nanotubes (CNTs). A theoretical model is developed incorporating the charging rate of the carbon nanotube, kinetics of all the plasma species, and the growth rate of the CNTs because of diffusion and accretion of ions on the catalyst nanoparticle. The three different carrier gases, i.e., argon (Ar), ammonia, and nitrogen, are considered in the present investigation, and flow rates of all the three carrier gases are varied individually (keeping the flow rates of hydrocarbon and hydrogen gas constant) to investigate the variations in the number densities of hydrocarbon and hydrogen ions in the plasma and their consequent effects on the height and radius of CNT. Based on the results obtained, it is concluded that Ar favors the formation of CNTs with larger height and radius whereas ammonia contributes to better height of CNT but decreases the radius of CNT, and nitrogen impedes both the height and radius of CNT. The present work can serve to the better understanding of process parameters during growth of CNTs by a plasma enhanced chemical vapor deposition process.

  8. Effects of flow and water chemistry on lead release rates from pipe scales.

    Science.gov (United States)

    Xie, Yanjiao; Giammar, Daniel E

    2011-12-01

    Lead release from pipe scales was investigated under different water compositions, stagnation times, and flow regimes. Pipe scales containing PbO(2) and hydrocerussite (Pb(3)(OH)(2)(CO(3))(2)) were developed on lead pipes by conditioning the pipes with water containing free chlorine for eight months. Water chemistry and the composition of the pipe scales are two key factors affecting lead release from pipe scales. The water rarely reached equilibrium with pipe scales within one day, which makes solid-water contact time and corrosion product dissolution rates the controlling factors of lead concentrations for the conditions tested. Among five water compositions studied, a solution with orthophosphate had the lowest dissolved lead release rate and highest particulate lead release rate. Free chlorine also decreased the dissolved lead release rate at stagnant conditions. Water flow increased rates of release of both dissolved and particulate lead by accelerating the mass transfer of lead out of the porous pipe scales and by physically destabilizing pipe scales. Dissolved lead comprised the majority of the lead released at both stagnant and laminar flow conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Prediction of FV520B Steel Flow Stresses at High Temperature and Strain Rates

    Science.gov (United States)

    Han, Xiaolan; Zhao, Shengdun; Zhang, Chenyang; Fan, Shuqin; Xu, Fan

    2015-10-01

    In order to develop reliable constitutive equations for the simulation, the hot deformation behavior of FV520B steel was investigated through isothermal compression tests in a wide range of temperatures from 900 °C to 1100 °C at an interval of 50 °C and strain rate from 0.01 to 10 s-1 on Gleeble-1500D simulator. The effects of temperature and strain rate on deformation behavior were represented by Zener-Holloman parameter in an exponent-type equation of Arrhenius constitutive. The influence of strain was incorporated in the constitutive analysis by material constants expressed as a polynomial function of strain. The constitutive equation (considering the compensation of strain) could precisely predict the flow stress only at strain rate 0.01 s-1 except at the temperatures of 900 °C and 1000 °C, whereas the flow stress predicted by a modified equation (incorporating both the strain and strain rate) demonstrated a well agreement with the experimental data throughout the entire range of temperatures and strain rates. Correlation coefficient (R) of 0.988 and average absolute relative error (AARE) of 5.7% verified the validity of developed equation from statistical analysis, which further confirmed that the modified constitutive equation could accurately predict the flow stress of FV520B steel.

  10. Stability of unstimulated and stimulated whole saliva flow rates in children.

    Science.gov (United States)

    Sánchez-Pérez, Leonor; Irigoyen-Camacho, Esther; Sáenz-Martínez, Laura; Zepeda Zepeda, Marco; Acosta-Gío, Enrique; Méndez-Ramírez, Ignacio

    2016-09-01

    To analyze the stability of the unstimulated saliva flow rate (USFR) and the stimulated saliva flow rate (SSFR) in children followed from age 7 to 12 years old. Longitudinal study. Whole saliva samples were collected from school children (50 girls and 50 boys). Forty-four girls and 32 boys remained in this cohort for 6 years (dropout rate 24%). Variables that could influence USFR or SSFR patterns were analyzed in a repeated-measures manova. Over a 6-year follow-up, the children's USFR ranged from 0.41 to 0.46 mL/min in the initial and final observation, respectively, and showed no significant differences (P = 0.4455) during the follow-up. The children consistently belonged to one of three distinct SSFR groups (P saliva for screening or diagnostic purposes. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. 7Q10 flows for SRS streams

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.F.

    1996-10-01

    The Environmental Transport Group of the Environmental Technology Section was requested to predict the seven-day ten-year low flow (7Q10 flow) for the SRS streams based on historical stream flow records. Most of the historical flow records for the SRS streams include reactor coolant water discharged from the reactors and process water released from the process facilities. The most straight forward way to estimate the stream daily natural flow is to subtract the measured upstream reactor and/or facility daily effluents from the measured downstream daily flow. Unfortunately, this method does not always work, as indicated by the fact that sometimes the measured downstream volumetric flow rates are lower than the reactor effluent volumetric flow rates. For those cases that cannot be analyzed with the simple subtracting method, an alternative method was used to estimate the stream natural flows by statistically separating reactor coolant and process water flow data. The correlation between the calculated 7Q10 flows and the watershed areas for Four Mile Branch and Pen Branch agrees with that calculated by the USGS for Upper Three Runs and Lower Three Runs Creeks. The agreement between these two independent calculations lends confidence to the 7Q10 flow calculations presented in this report.

  12. Relative viscosity of emulsions in simple shear flow: Temperature, shear rate, and interfacial tension dependence

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Se Bin; Lee, Joon Sang [Dept. of Mechanical Engineering, Yonsei Unversity, Seoul (Korea, Republic of)

    2015-08-15

    We simulate an emulsion system under simple shear rates to analyze its rheological characteristics using the lattice Boltzmann method (LBM). We calculate the relative viscosity of an emulsion under a simple shear flow along with changes in temperature, shear rate, and surfactant concentration. The relative viscosity of emulsions decreased with an increase in temperature. We observed the shear-thinning phenomena, which is responsible for the inverse proportion between the shear rate and viscosity. An increase in the interfacial tension caused a decrease in the relative viscosity of the decane-in-water emulsion because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress.

  13. Effect of flow rate and concentration difference on reverse electrodialysis system

    Science.gov (United States)

    Kwon, Kilsugn; Han, Jaesuk; Kim, Daejoong

    2013-11-01

    Various energy conversion technologies have been developed to reduce dependency on limited fossil fuels, including wind power, solar power, hydropower, ocean power, and geothermal power. Among them, reverse electrodialysis (RED), which is one type of salinity gradient power (SGP), has received much attention due to high reliability and simplicity without moving parts. Here, we experimentally evaluated the RED performance with several parameters like flow rate of concentrated and dilute solution, concentration difference, and temperature. RED was composed of endplates, electrodes, spacers, anion exchange membrane, and cation exchange membrane. Endplates are made by a polypropylene. It included the electrodes, flow field for the electrode rinse solution, and path to supply a concentrated and dilute solution. Titanium coated by iridium and ruthenium was used as the electrode. The electrode rinse solution based on hexacyanoferrate system is used to reduce the power loss generated by conversion process form ionic current to electric current. Maximum power monotonously increases as increasing flow rate and concentration difference. Net power has optimal point because pumping power consumption increases with flow rate. This work was supported by Basic Science Research Program (Grat No. NRF-2011-0009993) through the National Research Foundation of Korea.

  14. Comparison of emergence times with different fresh gas flow rates following desflurane anaesthesia.

    Science.gov (United States)

    Jeong, Ji Seon; Yoon, Sung Wook; Choi, Sung Lark; Choi, Sung Hwan; Lee, Bong Yeong; Jeong, Mi Ae

    2014-12-01

    To investigate emergence times with different fresh gas flow rates, following desflurane anaesthesia. Patients undergoing surgery with desflurane anaesthesia were randomly assigned to receive fresh gas flow rates of 100% oxygen during emergence of 2 l/min (group D2), 4 l/min (group D4) or 6 l/min (group D6). Time to eye opening, spontaneous movement and extubation (emergence time) were assessed after desflurane discontinuation. The end-tidal concentration of desflurane and bispectral index were recorded at each of these timepoints. A total of 105 patients were included in the study, with 35 in each of the three groups. Mean times to extubation were 17.6 min, 9.9 min and 9.1 min in groups D2, D4 and D6, respectively. Times to eye opening, spontaneous movement and extubation in group D2 were significantly longer than in groups D4 and D6. These results suggest that there is the potential to predict emergence time based on fresh gas flow rate following desflurane anaesthesia. It should therefore be possible to use a low-flow technique during the emergence period, in addition to the maintenance period, without delaying recovery if the inhaled anaesthetic is stopped at the predicted time before the end of surgery. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  15. Long-term flow-through column experiments and their relevance to natural granitoid weathering rates

    Science.gov (United States)

    White, Arthur F.; Schulz, Marjorie S.; Lawrence, Corey R.; Vivit, Davison V.; Stonestrom, David A.

    2017-01-01

    Four pairs of fresh and partly-weathered granitoids, obtained from well-characterized watersheds—Merced River, CA, USA; Panola, GA, USA; Loch Vale, CO, USA, and Rio Icacos, Puerto Rico—were reacted in columns under ambient laboratory conditions for 13.8 yrs, the longest running experimental weathering study to date. Low total column mass losses (flow rates. Effluent Na concentrations showed no clear trend with time during the last decade of reaction (fresh granitoids) or increased slowly with time (weathered granitoids). Analysis of cumulative Na release indicated that plagioclase dissolution achieved steady state in 3 of the 4 fresh granitoids during the last decade of reaction. Surface-area normalized plagioclase dissolution rates exhibited a narrow range (0.95 to 1.26 10-13 moles m-2 s-1), in spite of significant stoichiometric differences (An0.21 to An0.50). Rates were an order of magnitude slower than previously reported in shorter duration experiments but generally 2 to 3 orders of magnitude faster than corresponding natural analogs. CrunchFlow simulations indicated that more than a hundredfold decrease in column flow rates would be required to produce near-saturation reaction affinities that would start to slow plagioclase weathering to real-world levels. Extending simulations to approximate long term weathering in naturally weathered profiles required additional decreases in the intrinsic plagioclase dissolution and kaolinite precipitation rates and relatively large decreases in the fluid flow rate, implying that exposure to reactive mineral surfaces is significantly limited in the natural environment compared to column experiments.

  16. Real exchange rate, trade flows and foreign direct investments: the Moroccan case

    OpenAIRE

    Bouoiyour, Jamal; Rey, Serge

    2005-01-01

    We study the behavior of the Real Effective Exchange Rate (REER) of the dirham against the European currencies (the EU15), over the period 1960–2000. We measure the volatility using standard deviation, and the misalignments as the difference between the actual REER and the equilibrium REER (NATREX model). We show that a rise in the volatility of the dirham reduces the trade flows, i.e. the exports and the imports. The misalignments also affect the trade flows: an overvaluation leads to a redu...

  17. Venturi fouling and what can cause an overestimate of the flow rate by one percent

    Energy Technology Data Exchange (ETDEWEB)

    Hedberg, P. [Remote CAE AB, Gothenburg (Sweden); Nilsson, H. [Ringhals AB, Varobacka (Sweden)

    2011-07-01

    In this study, we are looking for phenomena which can explain the effect that venturi fouling has on the measurement of feedwater flow rate in a PWR, Unit 3 of Ringhals Nuclear Power Plant, Sweden. When hydrazine is injected into the feedwater, it reduces the deposits of magnetite on the wetted surface of the venturi, and elsewhere at the given temperature ~200°C. This changes the reading from the flow measuring device and becomes closer to the originally calibrated data. Over time magnetite is rebuilt on the walls. We are searching for what can overestimate the mass flow rate in the order of 1%. Potential explanations are; changes in the venturi cross section area, change in properties of the fluid mixture, effects of suspended magnetite particles, changes in wall shear stress due to regular wall roughness, changes in the wall shear stress due to self-organized ripple wall roughness, changes in swirling flow due to wall roughness, separation in the diffuser part of venturi due to wall roughness, changes in the velocity profile (entering the venturi) due to wall roughness, and local buildup of deposits around the pressure taps. Besides visual inspection of recently replaced venturi meters, numerical and theoretical estimates have been used to find the most likely explanation. We have derived a new wall function to introduce the self-organized ripple wall shear stress and used it in CFD (Computational Fluid Dynamics) simulations. The first conclusion from the simulations is that the required regular wall roughness is not consistent with the observed thickness of the deposit on the wetted surfaces. Nor does the cross section area change sufficiently to make the flow rate deviate by 1%. The changes in fluid properties, due to the fluid mixing, are not significant. This is also true for a fluid with suspended magnetite particles. The only effect that is large enough to overestimate the flow by 1% is the self-organized wall ripple, for the observed deposit thickness

  18. The efficacy of oxygen wafting using different delivery devices, flow rates and device positioning.

    Science.gov (United States)

    Blake, Denise F; Shih, Elizabeth M; Mateos, Paul; Brown, Lawrence H

    2014-08-01

    Oxygen "wafting" provides a non-contact oxygen alternative for uncooperative paediatric patients in the emergency department (ED). The aim of this study was to identify the combination of oxygen delivery device, flow rate and device positioning that delivers the highest concentration of wafted oxygen. ED nursing staff were surveyed to determine current oxygen wafting practice. A simulated patient and oxygen sensor were used to compare wafted oxygen concentrations for six delivery devices in various positions and oxygen flow rates. Only oxygen tubing and the paediatric non-rebreather mask consistently delivered wafted oxygen concentrations above 30%. The paediatric non-rebreather held below the face produced concentrations ranging from 26.1% (10 cm) to 39.8% (5 cm). At 15 L/min, tubing held in front of the face produced concentrations ranging from 31.2% (15 cm) to 56.7% (5 cm); reducing the flow rate to 6-8 L/min had no meaningful effect on the delivered oxygen concentration. When tubing was used below the face, flow rates between 6 and 8 L/min produced somewhat higher concentrations than 15 L/min (5 cm: 36.3% vs. 30.9%). When delivering oxygen by wafting, the highest oxygen concentrations are achieved when positioning tubing 5-15 cm in front of the face or positioning tubing or a paediatric non-rebreather mask 5-10 cm below the face at 10-15 L/min flow. This should be considered when using oxygen wafting in the ED. Copyright © 2014 College of Emergency Nursing Australasia Ltd. Published by Elsevier Ltd. All rights reserved.

  19. Non-contact flow gauging for the extension and development of rating curves

    Science.gov (United States)

    Perks, Matthew; Large, Andy; Russell, Andy

    2015-04-01

    Accurate measurement of river discharge is fundamental to understanding hydrological processes, associated hazards and ecological responses within fluvial systems. Established protocols for determining river discharge are partial, predominantly invasive and logistically difficult during high flows. There is demand for new methods for accurate quantification of flow velocity under high-flow/flood conditions to in turn enable better post-event reconstruction of peak discharge. As a consequence considerable effort has been devoted to the development of innovative technologies for the representation of flow in open channels. Remotely operated fixed and mobile systems capable of providing quantitative estimates of instantaneous and time-averaged flow characteristics using non-contact methods has been a major development. Amongst the new approaches for stand-alone continuous monitoring of surface flows is Large Scale Particle Image Velocimetry (LSPIV). Here we adapt the LSPIV concept, to provide continuous discharge measurements in non-uniform channels with complex flow conditions. High Definition videos (1080p; 30fps) of the water surface are acquired at 5 minute intervals. The image is rectified to correct for perspective distortion using a new, open source tool which minimises errors resulting from oblique image capture. Naturally occurring artefacts on the water surface (e.g. bubbles, debris, etc.) are tracked with the Kanade-Lucas-Tomasi (KLT) algorithm. The data generated is in the form of a complex surface water velocity field which can be interrogated to extract a range of hydrological information such as the streamwise velocity at a cross-section of interest, or even allow the interrogation of hydrodynamic flow structures. Here we demonstrate that this approach is capable of generating river discharge data comparable to concurrent measurements made using existing, accepted technologies (e.g. ADCP). The outcome is better constraint and extension of rating curves

  20. Clinical effect of Diskus dry-powder inhaler at low and high inspiratory flow-rates in asthmatic children

    DEFF Research Database (Denmark)

    Nielsen, K G; Auk, I L; Bojsen, K

    1998-01-01

    In vitro studies with the Diskus inhaler at low and high flow rates show consistent doses of drug as fine particles flow independency translates into flow-independent clinical effect when the device is used by patients...... at low (30 L x min[-1]) and high (90 L x min[-1]) flow rates. A pilot study in 129 children aged 3-10 yrs demonstrated that 99% of children of 3 yrs and above can generate a flow > or = 30 L x min(-1) through the device, while 26% performed > or = 90 L x min(-1). Eighteen children aged 8-15 yrs...... after salmeterol at either flow rates as compared to placebo. There was no significant difference in the protection from salmeterol on the day of low-flow inhalation versus the day of high-flow inhalation. Consistent in vitro fine particle dosing from the Diskus inhaler translates into a consistent...

  1. A volumetric ablation model of EPDM considering complex physicochemical process in porous structure of char layer

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2017-06-01

    Full Text Available A volumetric ablation model for EPDM (ethylene- propylene-diene monomer is established in this paper. This model considers the complex physicochemical process in the porous structure of a char layer. An ablation physics model based on a porous structure of a char layer and another model of heterogeneous volumetric ablation char layer physics are then built. In the model, porosity is used to describe the porous structure of a char layer. Gas diffusion and chemical reactions are introduced to the entire porous structure. Through detailed formation analysis, the causes of the compact or loose structure in the char layer and chemical vapor deposition (CVD reaction between pyrolysis gas and char layer skeleton are introduced. The Arrhenius formula is adopted to determine the methods for calculating carbon deposition rate C which is the consumption rate caused by thermochemical reactions in the char layer, and porosity evolution. The critical porosity value is used as a criterion for char layer porous structure failure under gas flow and particle erosion. This critical porosity value is obtained by fitting experimental parameters and surface porosity of the char layer. Linear ablation and mass ablation rates are confirmed with the critical porosity value. Results of linear ablation and mass ablation rate calculations generally coincide with experimental results, suggesting that the ablation analysis proposed in this paper can accurately reflect practical situations and that the physics and mathematics models built are accurate and reasonable.

  2. A volumetric ablation model of EPDM considering complex physicochemical process in porous structure of char layer

    Science.gov (United States)

    Yang, Liu; Xiao-Jing, Yu; Jian-Ming, Ma; Yi-Wen, Guan; Jiang, Li; Qiang, Li; Sa, Yang

    2017-06-01

    A volumetric ablation model for EPDM (ethylene- propylene-diene monomer) is established in this paper. This model considers the complex physicochemical process in the porous structure of a char layer. An ablation physics model based on a porous structure of a char layer and another model of heterogeneous volumetric ablation char layer physics are then built. In the model, porosity is used to describe the porous structure of a char layer. Gas diffusion and chemical reactions are introduced to the entire porous structure. Through detailed formation analysis, the causes of the compact or loose structure in the char layer and chemical vapor deposition (CVD) reaction between pyrolysis gas and char layer skeleton are introduced. The Arrhenius formula is adopted to determine the methods for calculating carbon deposition rate C which is the consumption rate caused by thermochemical reactions in the char layer, and porosity evolution. The critical porosity value is used as a criterion for char layer porous structure failure under gas flow and particle erosion. This critical porosity value is obtained by fitting experimental parameters and surface porosity of the char layer. Linear ablation and mass ablation rates are confirmed with the critical porosity value. Results of linear ablation and mass ablation rate calculations generally coincide with experimental results, suggesting that the ablation analysis proposed in this paper can accurately reflect practical situations and that the physics and mathematics models built are accurate and reasonable.

  3. Flow rate, syringe size and architecture are critical to start-up performance of syringe pumps.

    Science.gov (United States)

    Neff, S B; Neff, T A; Gerber, S; Weiss, M M

    2007-07-01

    Significant start-up delays are inherent to syringe infusion pumps, particularly at low infusion rates, as routinely used in children's anaesthesia and intensive care. Such delays are mainly the result of engagement of gears in the mechanical drive or compliance of the syringe assembly. The purpose of the present study was to determine the effect of flow rate, syringe size and syringe architecture on fluid delivery during infusion start-up. Elapsed time from infusion start to achievement of steady-state flow was gravimetrically determined for various infusion rates (0.1, 0.5, 1 mL h-1), different syringe sizes (10-, 20-, 30-, 50-mL) and syringes of two different brands (BD and Codan). Four measurements for each condition were performed with two identical Alaris Asena GH syringe infusion pumps (total of eight experiments). Statistical analysis was done by two-way ANOVA with Bonferroni's post-test; P brand in comparison with the Codan syringes (P < 0.01). Highest possible flow rate, smaller sized syringes and syringe plungers with reduced compressibility should be preferred in order to avoid significant start-up delays in fluid delivery.

  4. Primary standard for liquid flow rates between 30 and 1500 nl/min based on volume expansion.

    Science.gov (United States)

    Lucas, Peter; Ahrens, Martin; Geršl, Jan; Sparreboom, Wouter; Lötters, Joost

    2015-08-01

    An increasing number of microfluidic systems operate at flow rates below 1 μl/min. Applications include (implanted) micropumps for drug delivery, liquid chromatography, and microreactors. For the applications where the absolute accuracy is important, a proper calibration is required. However, with standard calibration facilities, flow rate calibrations below ~1 μl/min are not feasible because of a too large calibration uncertainty. In the current research, a traceable flow rate using a certain temperature increase rate is proposed. When the fluid properties, starting mass, and temperature increase rate are known, this principle yields a direct link to SI units, which makes it a primary standard. In this article, it will be shown that this principle enables flow rate uncertainties in the order of 2-3% for flow rates from 30 to 1500 nl/min.

  5. Emergence and decay rate of the edge plasma flow shear near a critical transition

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J M; Garcia, L [Universidad Carlos III, 28911 Leganes, Madrid (Spain); Carreras, B A [BACV Solutions, Inc, Oak Ridge, Tennessee 37830 (United States)], E-mail: jmdelgad@fis.uc3m.es

    2009-01-15

    Recently, the experimental results for the emergence of the plasma shear flow layer in TJ-II have been explained as a second-order phase transition like process by using a simple model of envelope equations for the fluctuation level, the averaged poloidal velocity shear and the pressure gradient (2006 Phys. Plasmas 13 122509). Here, we extend this model by incorporating radial coupling. The model is applied to the study of the turbulence-shear flow interaction when the energy flux is low. Transition dynamics and their concomitant thresholds are examined within the context of this model. The effect of an external torque induced by electrode biasing has also been considered. In particular, we analyze the decay rate of the shear flow after switching off the biasing.

  6. Maximum two-phase flow rates of subcooled nitrogen through a sharp-edged orifice

    Science.gov (United States)

    Simoneau, R. J.

    1975-01-01

    An experiment was conducted and data are presented in which subcooled liquid nitrogen was discharged through a sharp-edged orifice at flow rates near the maximum. The data covered a range of inlet stagnation pressure from slightly above saturation to twice the thermodynamic critical pressure. The data were taken along five separate inlet stagnation isotherms ranging from 0.75 to 1.035 times the thermodynamic critical temperature. The results indicate that: (1) subcooled liquids do not choke or approach maximum flow in an asymptotic manner even though the back pressure is well below saturation; (2) orifice flow coefficients are not constant as is frequently assumed. A metastable jet appears to exist which breaks down if the difference between back pressure and saturation pressure is large enough.

  7. Intrapericardial denervation - Radial artery blood flow and heart rate responses to LBNP

    Science.gov (United States)

    Mckeever, Kenneth H.; Skidmore, Michael G.; Keil, Lanny C.; Sandler, Harold

    1990-01-01

    The effects of intrapericardial denervation on the radial artery blood flow velocity (RABFV) and heart rate (HR) responses to LBNP in rhesus monkeys were investigated by measuring the RABFV transcutaneously by a continuous-wave Doppler ultrasonic flowmeter in order to derive an index of forearm blood flow response to low (0 to -20 mm Hg) and high (0 to -60 mm Hg) ramp exposures during supine LBNP. Four of the eight subjects were subjected to efferent and afferent cardiac denervation. It was found that, during low levels of LBNP, monkeys with cardiac denervation exhibited no cardiopulmonary baroreceptor-mediated change in the RABFV or HR, unlike the intact animals, which showed steady decreases in RABFV during both high- and low-pressure protocols. It is suggested that forearm blood flow and HR responses to low-level LBNP, along with pharmacological challenge, are viable physiological tests for verifying the completeness of atrial and cardiopulmonary baroreceptor denervation.

  8. An extracorporeal carbon dioxide removal (ECCO2R) device operating at hemodialysis blood flow rates.

    Science.gov (United States)

    Jeffries, R Garrett; Lund, Laura; Frankowski, Brian; Federspiel, William J

    2017-09-06

    Extracorporeal carbon dioxide removal (ECCO2R) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCO2R device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry. A carbon dioxide (CO2) removal device was fabricated with rotating impellers inside an annular hollow fiber membrane bundle to disrupt blood flow patterns and enhance gas exchange. In vitro gas exchange and hemolysis testing was conducted at hemodialysis blood flows (250 mL/min). In vitro carbon dioxide removal rates up to 75 mL/min were achieved in blood at normocapnia (pCO2 = 45 mmHg). In vitro hemolysis (including cannula and blood pump) was comparable to a Medtronic Minimax oxygenator control loop using a time-of-therapy normalized index of hemolysis (0.19 ± 0.04 g/100 min versus 0.12 ± 0.01 g/100 min, p = 0.169). In vitro performance suggests a new ultra-low-flow extracorporeal CO2 removal device could be utilized for safe and effective CO2 removal at hemodialysis flow rates using simplified and minimally invasive connection strategies.

  9. Dynamics, OH distributions and UV emission of a gliding arc at various flow-rates investigated by optical measurements

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Sun, Zhiwei; Li, Zhongshan

    2014-01-01

    We demonstrate a plasma discharge which is generated between two diverging electrodes and extended into a gliding arc in non-equilibrium condition by an air flow at atmospheric pressure. Effects of the air flow rates on the dynamics, ground-state OH distributions and spectral characterization of UV...... occur more frequently at higher flow rates. The anchor points of the gliding arc are mostly steady at the top of the electrodes at lower flow rates whereas at higher flow rates they glide up along the electrodes most of the time. The afterglow of fully developed gliding arcs is observed to decay over......-state OH were investigated using planar laser-induced fluorescence. The results show that the shape, height, intensity and thickness of ground-state OH distribution vary significantly with air flow rates. Finally, UV emission of the gliding arc is measured using optical emission spectroscopy...

  10. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  11. Fluorophotometric determination of aqueous humor flow rates in red-tailed hawks (Buteo jamaicensis).

    Science.gov (United States)

    Jones, Michael P; Ward, Daniel A

    2012-04-01

    To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry. 9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age. A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates. Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species. The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.

  12. Turbulent transport measurements in a cold model of GT-burner at realistic flow rates

    Directory of Open Access Journals (Sweden)

    Gobyzov Oleg

    2016-01-01

    Full Text Available In the present work simultaneous velocity field and passive admixture concentration field measurements at realistic flow-rates conditions in a non-reacting flow in a model of combustion chamber with an industrial mixing device are reported. In the experiments for safety reasons the real fuel (natural gas was replaced with neon gas to simulate stratification in a strongly swirling flow. Measurements were performed by means of planar laser-induced fluorescence (PLIF and particle image velocimetry technique (PIV at Reynolds number, based on the mean flow rate and nozzle diameter, ≈300 000. Details on experimental technique, features of the experimental setup, images and data preprocessing procedures and results of performed measurements are given in the paper. In addition to the raw velocity and admixture concentration data in-depth evaluation approaches aimed for estimation of turbulent kinetic energy (TKE components, assessment of turbulent Schmidt number and analysis of the gradient closure hypothesis from experimental data are presented in the paper.

  13. Analytical expressions for optimum flow rates in evaporators and condensers of heat pumping systems

    Energy Technology Data Exchange (ETDEWEB)

    Granryd, E. [Dept. of Energy Technology, Royal Institute of Technology, KTH, Stockholm (Sweden)

    2010-11-15

    The flow velocities on the air or liquid side of evaporators and condensers in refrigerating or heat pump systems affect the system performance considerably. Furthermore the velocity can often be chosen rather freely without obvious first cost implications. The purpose of the paper is to show analytical relations indicating possible optimum operating conditions. Considering a base case where the design data are known, simple analytical relations are deduced for optimum flow rates that will result in highest overall COP of the system when energy demand for the compressor as well as pumps or fans are included. This optimum is equivalent to the solution for minimum total energy demand of the system for a given cooling load. It is also shown that a different (and higher) flow rate will result in maximum net cooling capacity for a refrigerating system with fixed compressor speed. The expressions can be used for design purposes as well as for checking suitable flow velocities in existing plants. The relations may also be incorporated in algorithms for optimal operation of systems with variable speed compressors. (author)

  14. Estimation of inlet flow rates for image-based aneurysm CFD models: where and how to begin?

    Science.gov (United States)

    Valen-Sendstad, Kristian; Piccinelli, Marina; KrishnankuttyRema, Resmi; Steinman, David A

    2015-06-01

    Patient-specific flow rates are rarely available for image-based computational fluid dynamics models. Instead, flow rates are often assumed to scale according to the diameters of the arteries of interest. Our goal was to determine how choice of inlet location and scaling law affect such model-based estimation of inflow rates. We focused on 37 internal carotid artery (ICA) aneurysm cases from the Aneurisk cohort. An average ICA flow rate of 245 mL min(-1) was assumed from the literature, and then rescaled for each case according to its inlet diameter squared (assuming a fixed velocity) or cubed (assuming a fixed wall shear stress). Scaling was based on diameters measured at various consistent anatomical locations along the models. Choice of location introduced a modest 17% average uncertainty in model-based flow rate, but within individual cases estimated flow rates could vary by >100 mL min(-1). A square law was found to be more consistent with physiological flow rates than a cube law. Although impact of parent artery truncation on downstream flow patterns is well studied, our study highlights a more insidious and potentially equal impact of truncation site and scaling law on the uncertainty of assumed inlet flow rates and thus, potentially, downstream flow patterns.

  15. Design and optimization of a large flow rate booster pump in SWRO energy recovery system

    Science.gov (United States)

    Lai, Z. N.; Wu, P.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    Seawater reverse osmosis (SWRO) is a high energy-consumption industry, so energy efficiency is an important issue. Energy recovery systems, which contain a pressure exchanger and a booster pump, are widely used in SWRO plants. As a key part of energy recovery system, the difficulty of designing booster pumps lies in high inlet pressure, high medium causticity and large flow rate. High inlet pressure adds difficulties to seal design, and large flow rate and high efficiency requirement bring high demand for hydraulic design. In this paper, a 625 m3/h booster pump is designed and optimized according to the CFD (Computational Fluid Dynamics) simulation results. The impeller and volute is well designed, a new type of high pressure mechanical seal is applied and axial force is well balanced. After optimization based on blade redesign, the efficiency of the pump was improved. The best efficiency reaches more than 85% at design point according to the CFD simulation result.

  16. Investigations on efficiencies of HT solar collectors for different flow rates and collector tilts

    DEFF Research Database (Denmark)

    Chen, Ziqian; Perers, Bengt; Furbo, Simon

    2013-01-01

    Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between the abso......Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates and tilt. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rates are obtained. The calculated efficiencies are in good...

  17. The effect of flow rate on the oscillatory activation energy of an oscillating reaction

    Science.gov (United States)

    Monteiro, Emily V.; Varela, Hamilton; Faria, Roberto B.

    2017-09-01

    The simultaneous influence of temperature and flow rate (k0) in the oscillatory regime of the bromate-oxalic acid-acetone-Ce(III) oscillating reaction was investigated. The influence of temperature was evaluated in terms of the oscillatory activation energy (Eω), which was determined at different flow rates. Increasing k0, the oscillatory activation energy is decreased, tending to a limit value, Eω∞. The sensitivity of Eω with k0 is described by the parameter η = dEω/d(1/k0). Eω∞ and η are global properties of any particular oscillating reaction and describes a correlation between the dynamical behavior and temperature, and should be used when comparing different oscillating reactions.

  18. A micromixer with consistent mixing performance for a wide range of flow rates.

    Science.gov (United States)

    Goovaerts, Robert; Van Assche, Tom; Sonck, Marc; Denayer, Joeri; Desmet, Gert

    2015-02-01

    A micromixer with consistent mixing performance for a wide range of flow rates is presented. The mixer makes use of internally moving elements, i.e. steel balls that are located in dedicated mixing chambers. Movement is induced by a rotating magnetic field. To get better insight in differences between active and passive mixing, we studied a mixer that can operate in both regimes. A mixing performance study for a range of flow rates along with pressure drop data is presented. The response of the moving elements in regard to the magnetic field is shown experimentally and shows the limitations of earlier modeling studies. Lastly, the estimated power input on the fluids was calculated and allows for a comparison with more well-known convective-type mixers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Salivary buffer capacity, pH, and stimulated flow rate of crack cocaine users.

    Science.gov (United States)

    Woyceichoski, Iverson Ernani Cogo; Costa, Carlos Henrique; de Araújo, Cristiano Miranda; Brancher, João Armando; Resende, Luciane Grochocki; Vieira, Iran; de Lima, Antonio Adilson Soares

    2013-08-01

    Crack cocaine is the freebase form of cocaine that can be smoked. The use of this drug has been considered a public health problem in many countries. The aim of this study was to assess the stimulated salivary flow rate (SSFR), pH, and the buffer capacity of saliva in crack cocaine users. Stimulated whole saliva was collected from 54 selected crack cocaine users and 40 non-users. All samples were analyzed for SSFR, pH, and buffer capacity. SSFR was analyzed by gravimetric method. The buffer capacity and pH were determined using a digital pH meter. The crack cocaine users demonstrated higher buffer capacity than the control group (P > 0.05). Salivary pH was lower in crack cocaine users (P 0.05). Crack cocaine users might exhibit a significant decrease in salivary pH, but not in salivary flow rate or buffer capacity. © 2012 Blackwell Publishing Asia Pty Ltd.

  20. Model Reference Adaptive Control of the Air Flow Rate of Centrifugal Compressor Using State Space Method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Yi, Sun [North Carolina A and T State Univ., Raleigh (United States)

    2016-08-15

    In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.

  1. Intergenic DNA sequences from the human X chromosome reveal high rates of global gene flow

    Directory of Open Access Journals (Sweden)

    Wall Jeffrey D

    2008-11-01

    Full Text Available Abstract Background Despite intensive efforts devoted to collecting human polymorphism data, little is known about the role of gene flow in the ancestry of human populations. This is partly because most analyses have applied one of two simple models of population structure, the island model or the splitting model, which make unrealistic biological assumptions. Results Here, we analyze 98-kb of DNA sequence from 20 independently evolving intergenic regions on the X chromosome in a sample of 90 humans from six globally diverse populations. We employ an isolation-with-migration (IM model, which assumes that populations split and subsequently exchange migrants, to independently estimate effective population sizes and migration rates. While the maximum effective size of modern humans is estimated at ~10,000, individual populations vary substantially in size, with African populations tending to be larger (2,300–9,000 than non-African populations (300–3,300. We estimate mean rates of bidirectional gene flow at 4.8 × 10-4/generation. Bidirectional migration rates are ~5-fold higher among non-African populations (1.5 × 10-3 than among African populations (2.7 × 10-4. Interestingly, because effective sizes and migration rates are inversely related in African and non-African populations, population migration rates are similar within Africa and Eurasia (e.g., global mean Nm = 2.4. Conclusion We conclude that gene flow has played an important role in structuring global human populations and that migration rates should be incorporated as critical parameters in models of human demography.

  2. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    OpenAIRE

    Masafumi Nozoe; Kyoshi Mase; Tomoyuki Ogino; Shigefumi Murakami; Sachie Takashima; Kazuhisa Domen

    2016-01-01

    Background: Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receivi...

  3. Development and evaluation of a meter for measuring return line fluid flow rates during drilling

    Energy Technology Data Exchange (ETDEWEB)

    Loeppke, G.E.; Schafer, D.M.; Glowka, D.A.; Scott, D.D.; Wernig, M.D. (Sandia National Labs., Albuquerque, NM (United States)); Wright, E.K. (Ktech Corp., Albuquerque, NM (United States))

    1992-06-01

    The most costly problem routinely encountered in geothermal drilling is lost circulation, which occurs when drilling fluid is lost to the formation rather than circulating back to the surface. The successful and economical treatment of lost circulation requires the accurate measurement of drilling fluid flow rate both into and out of the well. This report documents the development of a meter for measuring drilling fluid outflow rates in the return line of a drilling rig. The meter employs a rolling counterbalanced float that rides on the surface of the fluid in the return line. The angle of the float pivot arm is sensed with a pendulum potentiometer, and the height of the float is calculated from this measurement. The float height is closely related to the fluid height and, therefore, the flow rate in the line. The prototype rolling float meter was extensively tested under laboratory conditions in the Wellbore Hydraulics Flow Facility; results from these tests were used in the design of the field prototype rolling float meter. The field prototype meter was tested under actual drilling conditions in August and September 1991 at the Long Valley Exploratory Well near Mammoth Lakes, Ca. In addition, the performance of several other commercially available inflow and outflow meters was evaluated in the field. The tested inflow meters included conventional pump stroke counters, rotary pump speed counters, magnetic flowmeters, and an ultrasonic Doppler flowmeter. On the return flow line, a standard paddlemeter, an acoustic level meter, and the prototype rolling float meter were evaluated for measuring drilling fluid outflow rates.

  4. Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks

    OpenAIRE

    Jun Wang; Min Song

    2007-01-01

    Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme u...

  5. Predicting Hourly Traflc Noise from Traflc Flow Rate Model: Underlying Concepts for the DYNAMAP Project

    OpenAIRE

    Smiraglia M.; Benocci R.; Zambon G.; Roman H.E.

    2016-01-01

    The DYNAMAP project aims at obtaining a dynamic noise map of a large residential area such as the City of Milan (Italy), by recording traffic noise from a limited number of noise sensors. To this end,we perform a statistical analysis of road stretches and group them into different clusters showing a similar measured hourly traffic noise behavior. In the sameway,we group simulated hourly traffic flow rates and compare their compositions with those of the traffic noise g...

  6. Determination of salivary flow rate, pH, and dental caries during pregnancy: A study

    Directory of Open Access Journals (Sweden)

    Amruta A Karnik

    2015-01-01

    Full Text Available Introduction: Saliva is an important diagnostic biofluid and the salivary composition is affected by various systemic conditions including pregnancy. Aims: The study was conducted to evaluate the salivary flow rate and pH in pregnant and non-pregnant Indian women and, consequently, to compare and correlate the salivary flow rate, pH, and prevalence of dental caries in both groups. Settings and Design: A cross-sectional study was conducted in our institute on a sample of 30 pregnant and 30 non-pregnant women. Materials and Methods: The clinical findings for Decayed-Missing-Filled Teeth (DMFT index were recorded. Unstimulated whole saliva was collected to determine the salivary flow rate and pH. Statistical Analysis Used: Data were statistically analyzed using Student′s t-test. Results: Salivary flow rate was lower in pregnant women (0.63 ml/min as compared to that in non-pregnant women (0.81 ml/min (P < 0.05 and the pH was also lesser in pregnant women (6.56 than in non-pregnant women (6.86 (P < 0.05. DMFT index showed a strong negative correlation with pH in pregnant women and non-pregnant women (P < 0.05. Conclusion: A difference was observed between the salivary parameters of pregnant and non-pregnant women in this sample. However, all the values were within the normal range. A significant inverse relation was found between salivary pH and dental caries for both the groups.

  7. Porcine In Vivo Validation of a Virtual Contrast Model: The Influence of Contrast Agent Properties and Vessel Flow Rates.

    Science.gov (United States)

    Peach, T W; Ventikos, Y; Byrne, J V; You, Z

    2016-12-01

    Accurately and efficiently modeling the transport of angiographic contrast currently offers the best method of verifying computational fluid dynamics simulations and, with it, progress toward the lofty goal of prediction of aneurysm treatment outcome a priori. This study specifically examines the influence of estimated flow rate and contrast properties on such in silico predictions of aneurysm contrast residence and decay. Four experimental sidewall aneurysms were created in swine, with aneurysm contrast flow patterns and decay rates observed under angiography. A simplified computational fluid dynamics model of the experimental aneurysm was constructed from 3D angiography and contrast residence predicted a priori. The relative influence of a number of estimated model parameters (contrast viscosity, contrast density, and blood flow rate) on contrast residence was then investigated with further simulations. Contrast infiltration and washout pattern were accurately predicted by the a priori computational fluid dynamics model; however, the contrast decay rate was underestimated by ∼25%. This error was attributed to the estimated parent vessel flow rate alone, and the effects of contrast viscosity and density on the decay rate were found to be inconsequential. A linear correlation between the parent vessel flow rate and the corresponding contrast decay rate was observed. In experimental sidewall aneurysms, contrast fluid properties (viscosity and density) were shown to have a negligible effect on variation in the modeled contrast decay rate. A strong linear correlation was observed between parent vessel flow rate and contrast decay over a physiologically reasonable range of flow rates. © 2016 by American Journal of Neuroradiology.

  8. Heart rate in the pathophysiology of coronary blood flow and myocardial ischaemia: benefit from selective bradycardic agents

    Science.gov (United States)

    Heusch, G

    2008-01-01

    Starting out from a brief description of the determinants of coronary blood flow (perfusion, pressure, extravascular compression, autoregulation, metabolic regulation, endothelium-mediated regulation and neurohumoral regulation) the present review highlights the overwhelming importance of metabolic regulation such that coronary blood flow is increased at increased heart rate under physiological circumstances and the overwhelming importance of extravascular compression such that coronary blood flow is decreased at increased heart rate through reduction of diastolic duration in the presence of severe coronary stenoses. The review goes on to characterize the role of heart rate in the redistribution of regional myocardial blood flow between a normal coronary vascular tree with preserved autoregulation and a poststenotic vasculature with exhausted coronary reserve. When flow is normalized by heart rate, there is a consistent close relationship of regional myocardial blood flow and contractile function for each single cardiac cycle no matter whether or not there is a coronary stenosis and what the actual blood flow is. β-Blockade improves both flow and function along this relationship. When the heart rate reduction associated with β-blockade is prevented by pacing, α-adrenergic coronary vasoconstriction is unmasked and both flow and function are deteriorated. Selective heart rate reduction, however, improves both flow and function without any residual negative effect such as unmasked α-adrenergic coronary vasoconstriction or negative inotropic action. PMID:18223669

  9. Atomistic Origin of Rate-Dependent Serrated Plastic Flow in Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Yao YG

    2008-01-01

    Full Text Available Abstract Nanoindentation simulations on a binary metallic glass were performed under various strain rates by using molecular dynamics. The rate-dependent serrated plastic flow was clearly observed, and the spatiotemporal behavior of its underlying irreversible atomic rearrangement was probed. Our findings clearly validate that the serration is a temporally inhomogeneous characteristic of such rearrangements and not directly dependent on the resultant shear-banding spatiality. The unique spatiotemporal distribution of shear banding during nanoindentation is highlighted in terms of the potential energy landscape (PEL theory.

  10. Characterization of a Porous Nano-electrospray Capillary Emitter at Ultra-low Flow Rates.

    Science.gov (United States)

    Jarvas, Gabor; Fonslow, Bryan; Yates, John R; Foret, Frantisek; Guttman, Andras

    2017-01-01

    Biopharmaceuticals, especially therapeutic monoclonal antibodies, have emerged as a very promising new generation of protein-based drugs. However, their comprehensive analysis continues to pose new challenges for the bioanalytical field. Hyphenation of capillary electrophoresis with electrospray ionization (CE-MS) is a promising technique to address these challenges. One of the main advantages of CE-MS is the ability to produce stable electrospray at ultra-low flow rates (5-20 nl/min range). In this short communication we report on the characterization of a porous nano-electrospray capillary emitter focusing on the effects of ultra-low flow rate on ionization efficiency, ion suppression and detection sensitivity. Ion suppression effect of a poorly-ionizable sugar in the presence of an easily-ionized peptide was reduced by almost 2-fold. Intact therapeutic antibody infusion analysis demonstrated that MS detection sensitivity increased by an order of magnitude with the decrease of flow rate from 250 nL/min to 20 nL/min using the nano-electrospray capillary emitter. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Relationship between xerostomia and salivary flow rates in HIV-infected individuals.

    Science.gov (United States)

    Nittayananta, Wipawee; Chanowanna, Nilnara; Pruphetkaew, Nannapat; Nauntofte, Birgitte

    2013-08-01

    The aim of the present study was to determine the relationship between self-reported xerostomia and salivary flow rates among HIV-infected individuals. A cross-sectional study was performed on 173 individuals (81 HIV-infected individuals, mean age: 32 years, and 92 non-HIV controls, mean age: 30 years). Subjective complaints of dry mouth, based on a self-report of xerostomia questions, and dry mouth, based on a visual analogue scale (VAS), were recorded along with measurements of salivary flow rate of both unstimulated and wax-stimulated whole saliva. The relationship between subjective responses to the xerostomia questions, the VAS of dry mouth, and objective measurements of salivary flow rates were analyzed. Responses to the questions--Do you carry water or a saliva substitute? and Have you had taste disturbance?--were significantly different between HIV-infected and non-HIV individuals (P hyposalivation, especially at a resting stage. © 2013 Wiley Publishing Asia Pty Ltd.

  12. Salivary flow rate and biochemical composition analysis in stimulated whole saliva of children with cystic fibrosis.

    Science.gov (United States)

    da Silva Modesto, Karine Barros; de Godói Simões, Jéssica Bueno; de Souza, Amanda Ferreira; Damaceno, Neiva; Duarte, Danilo Antonio; Leite, Mariana Ferreira; de Almeida, Eliete Rodrigues

    2015-11-01

    It is recognized that cystic fibrosis (CF) patients present a risk for oral diseases, since it affects exocrine glands, and the treatment consists of a carbohydrate-rich diet. Recognizing the protective function of saliva on maintaining oral health, the aim of the study was to evaluate salivary parameters in stimulated whole saliva from children with CF. A case-control study was conducted comparing stimulated whole saliva of healthy (n=28; control group) and CF children (n=21; experimental group). Salivary flow rate, initial pH, buffer capacity (total and in each range of pH), total protein and sialic acid (total, free, and conjugated) concentration, α-amylase and salivary peroxidase activities were evaluated. Data were compared by two-tailed Student t test (95% CI; p ≤ 0.05). CF patients presented a significant reduction in salivary parameters compared with the control group (p ≤ 0.05): salivary flow rate (36%), buffer capacity (pH range from 6.9 to 6.0), sialic acid concentration (total 75%, free 61%, and conjugated 83%); α-amylase and salivary peroxidase activities (55%). Additionally, a significant increase in total protein concentration (180%) of stimulated whole saliva from CF patients was verified compared with the control group (p ≤ 0.05). Children with CF presented significant changes in salivary composition, including salivary flow rate, buffering capacity and protective proteins of the oral cavity, compared with children without CF. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Effect of flow rate on the enhancement of particulate fouling in the presence of a developing biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Burton, G.R.; Blimkie, M.E.; McGarvey, G.B.; Turner, C.W

    2001-03-01

    The rate of magnetite deposition on a heated test section was investigated using radiotracing methods as a function of flow rate in the absence and presence of a growing biofilm of Pseudomonas fluorescens. The flow rate was adjusted to span Reynolds numbers from 2200 to 9600. For all flow rates, there was an increase in the rate of magnetite deposition in the presence of the growing biofilm. In addition, the rate of deposition was 10 times greater for a Reynolds number of 6400 than that observed at lower and higher flow rates with Reynolds numbers of 2200 and 9600, respectively. The results are discussed in relation to the shear stress on the biofilm and to the rate of transport of nutrients. (author)

  14. Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

    Science.gov (United States)

    Nema, V. K.; Sharma, O. P.

    1986-01-01

    To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

  15. Remote monitoring of volumetric discharge employing bathymetry determined from surface turbulence metrics

    Science.gov (United States)

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

    2016-03-01

    Current methods employed by the United States Geological Survey (USGS) to measure river discharge are manpower intensive, expensive, and during high flow events require field personnel to work in dangerous conditions. Indirect methods of estimating river discharge, which involve the use of extrapolated rating curves, can result in gross error during high flow conditions due to extrapolation error and/or bathymetric change. Our goal is to develop a remote method of monitoring volumetric discharge that reduces costs at the same or improved accuracy compared with current methods, while minimizing risk to field technicians. We report the results of Large-Scale Particle Image Velocimetry (LSPIV) and Acoustic Doppler Velocimetry (ADV) measurements conducted in a wide-open channel under a range of flow conditions, i.e., channel aspect ratio (B/H = 6.6-31.9), Reynolds number (ReH = 4,950-73,800), and Froude number (Fr = 0.04-0.46). Experiments were carried out for two different channel cross sections (rectangular and asymmetric compound) and two bathymetric roughness conditions (smooth glass and rough gravel bed). The results show that the mean surface velocity normalized by the depth-averaged velocity (the velocity index) decreases with increasing δ*/H, where δ* is the boundary layer displacement thickness and that the integral length scales, L11,1 and L22,1, calculated on the free-surface vary predictably with the local flow depth. Remote determination of local depth-averaged velocity and flow depth over a channel cross section yields an estimate of volumetric discharge.

  16. The Effect of Decreasing Flow Rate on Cerebral Hemodynamics During Veno-Arterial Extracorporeal Membrane Oxygenation in Piglets

    NARCIS (Netherlands)

    Gerrits, L.C.; Heijst, A.F.J. van; Hopman, J.C.W.; Haan, A.F.J. de; Liem, K.D.

    2015-01-01

    To explore the influence of decreasing flow rate on cerebral hemodynamics during veno-arterial extracorporeal membrane oxygenation (va-ECMO), six normoxemic and six hypoxemic piglets were put on va-ECMO. The ECMO flow rate was decreased from the maximal achievable level to 50 mL min1 with steps of

  17. Endothelial cell dynamics under pulsating flows: significance of high versus low shear stress slew rates (d(tau)/dt).

    Science.gov (United States)

    Hsiai, Tzung K; Cho, Sung K; Honda, Henry M; Hama, Susan; Navab, Mohamad; Demer, Linda L; Ho, Chih-Ming

    2002-05-01

    Shear stress modulates endothelial cell (EC) remodeling via realignment and elongation. We provide the first evidence that the upstroke slopes of pulsatile flow, defined as shear stress slew rates (positive d(tau)/dt), affect significantly the rates at which ECs remodel. We designed a novel flow system to isolate various shear stress slew rates by precisely controlling the frequency, amplitude, and time-averaged shear stress (tau(ave)) of pulsatile flow. Bovine aortic endothelial cell (BAEC) monolayers were exposed to three conditions: (1) pulsatile flow (1 Hz) at high slew rate (293 dyn/cm2 s), (2) pulsatile flow (1 Hz) at low slew rate (71 dyn/cm2s), and (3) steady laminar flow at d(tau)/dt = 0. All of the three conditions were operated at tau(ave) = 50 dyn/cm2. BAEC elongation and alignment were measured over 17 h. We were able to demonstrate the effects of shear stress slew rates ((tau)/dt) on EC remodeling at a fixed spatial shear stress gradient (d(tau)/dx). We found that pulsatile flow significantly increased the rates at which EC elongated and realigned, compared to steady flow at d(tau)/dt = 0. Furthermore, EC remodeling was faster in response to high than to low slew rates at a given tau(ave).

  18. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Science.gov (United States)

    2010-07-01

    ... Class II Equivalent Methods for PM2.5 or PM10â2.5 § 53.53 Test for flow rate accuracy, regulation... are to be recorded with an analog recording device, the accuracy of the entire instrument-recorder... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Test for flow rate accuracy, regulation...

  19. The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

    Science.gov (United States)

    Wang, H. L.; Han, W.; Xu, M.

    2011-12-01

    Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

  20. The dispersion behaviour of dry powder inhalation formulations cannot be assessed at a single inhalation flow rate

    NARCIS (Netherlands)

    Grasmeijer, Floris; de Boer, Anne H.

    2014-01-01

    The dispersion performances of inhalation powders are often tested at only one inhalation flow rate in mechanistic formulation studies. This limited approach is challenged by studies showing that interactions exist between inhalation flow rate and the effects on dispersion performance of several

  1. Flow Rate Through Pigtail Catheter Used for Left Heart Decompression in an Artificial Model of Extracorporeal Membrane Oxygenation Circuit.

    Science.gov (United States)

    Kim, Won Ho; Hong, Tae Hee; Byun, Joung Hun; Kim, Jong Woo; Kim, Sung Hwan; Moon, Sung Ho; Park, Hyun Oh; Choi, Jun Young; Yang, Jun Ho; Jang, In Seok; Lee, Chung Eun; Yun, Jeong Hee

    In refractory cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (ECMO) can be initiated. Although left heart decompression can be accomplished by insertion of a left atrial (LA) or left ventricular (LV) cannula using a percutaneous pigtail catheter, the venting flow rate according to catheter size and ECMO flow rate is unknown. We developed an artificial ECMO circuit. One liter saline bag with its pressure set to 20 mm Hg was connected to ECMO to mimic LV failure. A pigtail catheter was inserted into the 1 L saline bag to simulate LV unloading. For each pigtail catheter size (5-8 Fr) and ECMO flow rate (2.0-4.0 L/min), the moving distance of an air bubble that was injected through a three-way stopcock was measured in the arterial pressure line between the pigtail catheter and ECMO inflow limb. The flow rate was then calculated. We obtained the following equation to estimate the pigtail catheter flow rate.Pigtail vent catheter flow rate (ml/min) = 8×ECMOflow rate(L /min)+9×pigtail catheter size(Fr)- 57This equation would aid in designing of a further study to determine optimal venting flow rate. To achieve optimal venting flow, our equation would enable selection of an adequate catheter size.

  2. Heavy ellipsoids in creeping shear flow: transitions of the particle rotation rate and orbit shape.

    Science.gov (United States)

    Lundell, Fredrik; Carlsson, Allan

    2010-01-01

    The motion of an inertial ellipsoid in a creeping linear shear flow of a Newtonian fluid is studied numerically. This constitutes a fundamental system that is used as a basis for simulations and analysis of flows with heavy nonspherical particles. The torque on the ellipsoid is given analytically by Jeffery [Proc. R. Soc. London, Ser. A 102, 161 (1922)]. This torque is coupled with the angular-momentum equation for the particle. The motion is then governed by the Stokes number St=rho(e)gammal(2)/mu, where rho(e) is the density of the ellipsoid, gamma is the rate of shear, l is the length of the major axis of the ellipsoid, and mu is the dynamic viscosity of the fluid. For low St (the numerical value depends on the aspect ratio of the particle), the particle motion is similar to the Jeffery orbits obtained for inertia-free particles with the addition of an orbit drift so that the particle eventually lies in the flow-gradient plane. At higher St, more drastic effects are seen. For particles oriented in the flow-gradient plane, the rotation rate increases rather abruptly to half the shear rate in a narrow range of St. For particles with other orientations, the motion goes from a kayaking motion to rotation around an oblique axis. It is suggested that, depending on aspect and density ratios, particle inertia might be sufficient to explain and model orbit drift observed previously at low Reynolds numbers. It is discussed how and when the assumption of negligible fluid inertia and strong particle inertia can be justified from a fundamental perspective for particles of different aspect ratios.

  3. Zonal rate model for stacked membrane chromatography. I: characterizing solute dispersion under flow-through conditions.

    Science.gov (United States)

    Francis, Patrick; von Lieres, Eric; Haynes, Charles A

    2011-08-05

    Conventional models of both packed-bed and stacked-membrane chromatography typically attribute elution band broadening to non-idealities within the column. However, when the column length to diameter ratio is greatly reduced, as in stacked-membrane chromatography, variations in solute residence times within the feed-distribution (inlet) and eluent-collection (outlet) manifolds can also contribute to band broadening. We report on a new zonal rate model (ZRM) for stacked-membrane chromatography that improves on existing hold-up volume models that rely on one plug-flow reactor and one stirred-tank reactor in series to describe dispersion of solute during transport into and out of the column. The ZRM radially partitions the membrane stack and the hold-up volumes within the inlet and outlet manifolds into zones to better capture non-uniform flow distribution effects associated with the large column diameter to height ratio. Breakthrough curves from a scaled-down anion-exchange membrane chromatography module using ovalbumin as a model protein were collected at flow rates ranging from 1.5 to 20 mL min(-1) under non-binding conditions and used to evaluate the ZRM as well as previous models. The ZRM was shown to be significantly more accurate in describing protein dispersion and breakthrough. The model was then used to decompose breakthrough data, where it was found that variations in solute residence time distributions within the inlet and outlet manifolds make the dominant contribution to solute dispersion over the recommended range of feed flow rates. The ZRM therefore identifies manifold design as a critical contributor to separation quality within stacked-membrane chromatography units. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Iterative reconstruction of volumetric particle distribution

    Science.gov (United States)

    Wieneke, Bernhard

    2013-02-01

    For tracking the motion of illuminated particles in space and time several volumetric flow measurement techniques are available like 3D-particle tracking velocimetry (3D-PTV) recording images from typically three to four viewing directions. For higher seeding densities and the same experimental setup, tomographic PIV (Tomo-PIV) reconstructs voxel intensities using an iterative tomographic reconstruction algorithm (e.g. multiplicative algebraic reconstruction technique, MART) followed by cross-correlation of sub-volumes computing instantaneous 3D flow fields on a regular grid. A novel hybrid algorithm is proposed here that similar to MART iteratively reconstructs 3D-particle locations by comparing the recorded images with the projections calculated from the particle distribution in the volume. But like 3D-PTV, particles are represented by 3D-positions instead of voxel-based intensity blobs as in MART. Detailed knowledge of the optical transfer function and the particle image shape is mandatory, which may differ for different positions in the volume and for each camera. Using synthetic data it is shown that this method is capable of reconstructing densely seeded flows up to about 0.05 ppp with similar accuracy as Tomo-PIV. Finally the method is validated with experimental data.

  5. Impact of flow rates in a cardiac cycle on correlations between advanced human carotid plaque progression and mechanical flow shear stress and plaque wall stress

    Directory of Open Access Journals (Sweden)

    Ferguson Marina

    2011-07-01

    Full Text Available Abstract Background Mechanical stresses are known to play important roles in atherosclerotic plaque initiation, progression and rupture. It has been well-accepted that atherosclerosis initiation and early progression correlate negatively with flow wall shear stresses (FSS. However, mechanisms governing advanced plaque progression are not well understood. Method In vivo serial MRI data (patient follow-up were acquired from 14 patients after informed consent. Each patient had 2-4 scans (scan interval: 18 months. Thirty-two scan pairs (baseline and follow-up scans were formed with slices matched for model construction and analysis. Each scan pair had 4-10 matched slices which gave 400-1000 data points for analysis (100 points per slice on lumen. Point-wise plaque progression was defined as the wall thickness increase (WTI at each data point. 3D computational models with fluid-structure interactions were constructed based on in vivo serial MRI data to extract flow shear stress and plaque wall stress (PWS on all data points to quantify correlations between plaque progression and mechanical stresses (FSS and PWS. FSS and PWS data corresponding to both maximum and minimum flow rates in a cardiac cycle were used to investigate the impact of flow rates on those correlations. Results Using follow-up scans and maximum flow rates, 19 out of 32 scan pairs showed a significant positive correlation between WTI and FSS (positive/negative/no significance correlation ratio = 19/9/4, and 26 out of 32 scan pairs showed a significant negative correlation between WTI and PWS (correlation ratio = 2/26/4. Corresponding to minimum flow rates, the correlation ratio for WTI vs. FSS and WTI vs. PWS were (20/7/5 and (2/26/4, respectively. Using baseline scans, the correlation ratios for WTI vs. FSS were (10/12/10 and (9/13/10 for maximum and minimum flow rates, respectively. The correlation ratios for WTI vs. PWS were the same (18/5/9, corresponding to maximum and minimum

  6. Impact of flow rates in a cardiac cycle on correlations between advanced human carotid plaque progression and mechanical flow shear stress and plaque wall stress.

    Science.gov (United States)

    Yang, Chun; Canton, Gador; Yuan, Chun; Ferguson, Marina; Hatsukami, Thomas S; Tang, Dalin

    2011-07-19

    Mechanical stresses are known to play important roles in atherosclerotic plaque initiation, progression and rupture. It has been well-accepted that atherosclerosis initiation and early progression correlate negatively with flow wall shear stresses (FSS). However, mechanisms governing advanced plaque progression are not well understood. In vivo serial MRI data (patient follow-up) were acquired from 14 patients after informed consent. Each patient had 2-4 scans (scan interval: 18 months). Thirty-two scan pairs (baseline and follow-up scans) were formed with slices matched for model construction and analysis. Each scan pair had 4-10 matched slices which gave 400-1000 data points for analysis (100 points per slice on lumen). Point-wise plaque progression was defined as the wall thickness increase (WTI) at each data point. 3D computational models with fluid-structure interactions were constructed based on in vivo serial MRI data to extract flow shear stress and plaque wall stress (PWS) on all data points to quantify correlations between plaque progression and mechanical stresses (FSS and PWS). FSS and PWS data corresponding to both maximum and minimum flow rates in a cardiac cycle were used to investigate the impact of flow rates on those correlations. Using follow-up scans and maximum flow rates, 19 out of 32 scan pairs showed a significant positive correlation between WTI and FSS (positive/negative/no significance correlation ratio = 19/9/4), and 26 out of 32 scan pairs showed a significant negative correlation between WTI and PWS (correlation ratio = 2/26/4). Corresponding to minimum flow rates, the correlation ratio for WTI vs. FSS and WTI vs. PWS were (20/7/5) and (2/26/4), respectively. Using baseline scans, the correlation ratios for WTI vs. FSS were (10/12/10) and (9/13/10) for maximum and minimum flow rates, respectively. The correlation ratios for WTI vs. PWS were the same (18/5/9), corresponding to maximum and minimum flow rates. Flow shear stress

  7. Influence of flow direction and flow rate on the initial adhesion of seven Listeria monocytogenes strains to fine polished stainless steel

    DEFF Research Database (Denmark)

    Skovager, Anne; Whitehead, Kathryn; Siegumfeldt, Henrik

    2012-01-01

    The effects of flow direction and shear stress on the adhesion of different strains of Listeria monocytogenes to fine polished stainless steel under liquid flow conditions were investigated. Furthermore, the relationship between cell surface properties and cell size and the initial adhesion rate ...

  8. Effect of inspiratory flow rate on the efficiency of carbon dioxide removal at tidal volumes below instrumental dead space.

    Science.gov (United States)

    Hurley, Edward H; Keszler, Martin

    2017-03-01

    The ability to ventilate babies with tidal volumes (VTs) below dead space has been demonstrated both in vivo and in vitro, though it appears to violate classical respiratory physiology. We hypothesised that this phenomenon is made possible by rapid flow of gas that penetrates the dead space allowing fresh gas to reach the lungs and that the magnitude of this phenomenon is affected by flow rate or how rapidly air flows through the endotracheal tube. We conducted two bench experiments. First, we measured the time needed for complete CO2 washout from a test lung to assess how fixed VT but different inflation flow rates affect ventilation. For the second experiment, we infused carbon dioxide at a low rate into the test lung, varied the inflation flow rate and adjusted the VT to maintain stable end tidal carbon dioxide (ETCO2). At all tested VTs, lower flow rate increased the time it took for CO2 to washout from the test lung. The effect was most pronounced for VTs below dead space. The CO2 steady-state experiment showed that ETCO2 increased when the flow rate decreased. Ventilating with a slower flow rate required a nearly 20% increase in VT for the same effective alveolar ventilation. Inflation flow rate affects the efficiency of CO2 removal with low VT. Our results are relevant for providers using volume-controlled ventilation or other modes that use low inflation flow rates because the VT required for normocapnia will be higher than published values that were generated using pressure-limited ventilation modes with high inflation flows. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  9. Intra-aneurysmal flow rates are reduced by two flow diverters: an experiment using tomographic particle image velocimetry in an aneurysm model.

    Science.gov (United States)

    Dennis, Kendall D; Rossman, Timothy L; Kallmes, David F; Dragomir-Daescu, Dan

    2015-12-01

    Limitations on treating large, giant, and wide-necked aneurysms with coiling have made flow diverters a promising alternative to current practice by supporting reconstruction of the parent artery. To assess the changes to fluid dynamics within an aneurysm by studying two different endoluminal flow diverters on a simple aneurysm model, using tomographic particle image velocimetry to determine which device would better minimize fluid flow into an aneurysm and observe any significant changes in aneurysm fluid structures. Steady velocity fields of the model's aneurysm dome and neck were measured at three inlet velocities (18, 39, and 59 cm/s) for two flow diverter diameters with different porosities and compared against a baseline case with no flow diverter. In the baseline case a large vortex was present inside the dome for all flow rates. However, both devices eliminated this main vortex at all flow rates and reduced the peak aneurysmal velocities by about 90%. A strong correlation between flow diverter porosity and flow reduction was found. In each case the inflow to the aneurysm shifted from the distal neck to the mid- or proximal neck after flow diverter placement. Even with this relatively simple experimental setup, we were able to observe the major flow field changes, which occurred immediately after the deployment of each flow diverter. Limitations of the study included a simplified geometry and steady-state flow. Constraints included model making and limited availability of flow diverters. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  10. Efficiency of autothermal thermophilic aerobic digestion under two different oxygen flow rates.

    Science.gov (United States)

    Aynur, Sebnem Koyunluoglu; Riffat, Rumana; Murthy, Sudhir

    2014-01-01

    The objective of this research was to understand the influence of oxygenation at two different oxygen flow rates (0.105 and 0.210 L/L/h) on autothermal thermophilic aerobic digestion (ATAD), and on the overall performance of Dual Digestion (DD). Profile experiments on an ATAD reactor showed that a significant portion of volatile fatty acids and ammonia were produced in the first 12 h period, and both followed first order kinetics. Ammonia concentrations of ATAD effluent were 1015 mg/L and 1450 mg/L, respectively, at the two oxygenation rates. Ammonia production was not complete in the ATAD reactor at the lower oxygenation rate. However, it was sufficient to maximize volatile solids reduction in the DD process. The biological heat of oxidations were 14,300 J/g Volatile Solids (VS) removed and 15,900 J/g VS removed for the two oxygen flow rates, respectively. The ATAD step provided enhanced digestion for the DD process with higher volatile solids removal and methane yield when compared to conventional digestion.

  11. Assessment of increased sampling pump flow rates in a disposable, inhalable aerosol sampler.

    Science.gov (United States)

    Stewart, Justin; Sleeth, Darrah K; Handy, Rod G; Pahler, Leon F; Anthony, T Renee; Volckens, John

    2017-03-01

    A newly designed, low-cost, disposable inhalable aerosol sampler was developed to assess workers personal exposure to inhalable particles. This sampler was originally designed to operate at 10 L/min to increase sample mass and, therefore, improve analytical detection limits for filter-based methods. Computational fluid dynamics modeling revealed that sampler performance (relative to aerosol inhalability criteria) would not differ substantially at sampler flows of 2 and 10 L/min. With this in mind, the newly designed inhalable aerosol sampler was tested in a wind tunnel, simultaneously, at flows of 2 and 10 L/min flow. A mannequin was equipped with 6 sampler/pump assemblies (three pumps operated at 2 L/min and three pumps at 10 L/min) inside a wind tunnel, operated at 0.2 m/s, which has been shown to be a typical indoor workplace wind speed. In separate tests, four different particle sizes were injected to determine if the sampler's performance with the new 10 L/min flow rate significantly differed to that at 2 L/min. A comparison between inhalable mass concentrations using a Wilcoxon signed rank test found no significant difference in the concentration of particles sampled at 10 and 2 L/min for all particle sizes tested. Our results suggest that this new aerosol sampler is a versatile tool that can improve exposure assessment capabilities for the practicing industrial hygienist by improving the limit of detection and allowing for shorting sampling times.

  12. Habitat availability vs. flow rate for the Pecos River, Part 1 : Depth and velocity availability.

    Energy Technology Data Exchange (ETDEWEB)

    James, Scott Carlton; Schaub, Edward F.; Jepsen, Richard Alan; Roberts, Jesse Daniel

    2004-02-01

    The waters of the Pecos River in New Mexico must be delivered to three primary users: (1) The Pecos River Compact: each year a percentage of water from natural river flow must be delivered to Texas; (2) Agriculture: Carlsbad Irrigation District has a storage and diversion right and Fort Sumner Irrigation District has a direct flow diversion right; and, (3) Endangered Species Act: an as yet unspecified amount of water is to support Pecos Bluntnose Shiner Minnow habitat within and along the Pecos River. Currently, the United States Department of Interior Bureau of Reclamation, the New Mexico Interstate Stream Commission, and the United States Department of the Interior Fish and Wildlife Service are studying the Pecos Bluntnose Shiner Minnow habitat preference. Preliminary work by Fish and Wildlife personnel in the critical habitat suggest that water depth and water velocity are key parameters defining minnow habitat preference. However, river flows that provide adequate preferred habitat to support this species have yet to be determined. Because there is a limited amount of water in the Pecos River and its reservoirs, it is critical to allocate water efficiently such that habitat is maintained, while honoring commitments to agriculture and to the Pecos River Compact. This study identifies the relationship between Pecos River flow rates in cubic feet per second (cfs) and water depth and water velocity.

  13. Performance of different PEEP valves and helmet outlets at increasing gas flow rates: a bench top study.

    Science.gov (United States)

    Isgrò, S; Zanella, A; Giani, M; Abd El Aziz El Sayed Deab, S; Pesenti, A; Patroniti, N

    2012-10-01

    Aim of the paper was to assess the performance of different expiratory valves and the resistance of helmet outlet ports at increasing gas flow rates. A gas flow-meter was connected to 10 different expiratory peep valves: 1 water-seal valve, 4 precalibrated fixed PEEP valves and 5 adjustable PEEP valves. Three new valves of each brand, set at different pressure levels (5-7.5-10-12.5-15 cmH(2)O, if available), were tested at increasing gas flow rates (from 30 to 150 L/min). We measured the pressure generated just before the valves. Three different helmets sealed on a mock head were connected at the inlet port with a gas flow-meter while the outlet was left clear. We measured the pressure generated inside the helmet (due to the flow-resistance of the outlet port) at increasing gas flow rates. Adjustable valves showed a variable degree flow-dependency (increasing difference between the measured and the expected pressure at increasing flow rates), while pre-calibrated valves revealed a flow-independent behavior. Water seal valve showed low degree flow-dependency. The pressures generated by the outlet port of the tested helmets ranged from 0.02 to 2.29 cmH(2)O at the highest gas flow rate. Adjustable PEEP valves are not suggested for continuous-flow CPAP systems as their flow-dependency can lead to pressures higher than expected. Precalibrated and water seal valves exhibit the best performance. Different helmet outlet ports do not significantly affect the pressure generated during helmet CPAP. In order to avoid iatrogenic complications gas flow and pressure delivered during helmet CPAP must always be monitored.

  14. Computed tomography angiography: the effect of different chaser flow rates, volumes, and fluids on contrast enhancement.

    Science.gov (United States)

    Behrendt, Florian F; Jost, Gregor; Pietsch, Hubertus; Keil, Sebastian; Mottaghy, Felix M; Günther, Rolf W; Mahnken, Andreas H

    2011-04-01

    The aim of this study was to intraindividually compare the effect of different chaser flow rates, volumes, and fluids on contrast enhancement in multidetector-row computed tomography. Multidetector-row computed tomography scanning of 5 dogs was performed under standardized conditions using an adapted injection protocol to ensure an identical iodine delivery rate of 1.0 gI/s and a total iodine dose of 300 mg/kg body weight (iopromide 300 and 370). The contrast medium application was followed by a 10-mL saline chaser at different injection rates (0, 2.7, 4, 6, and 8 mL/s) or by different saline chaser volumes (0, 5, 10, and 15 mL) at a flow rate of 4 mL/s. Furthermore, different chaser fluids (NaCl, hydroxyethyl starch 10%, and Dextran 1%) with different viscosities (hydroxyethyl starch 10% and dextran 1%: 3.28 and 5.98 mPa · s at 37°C) were tested (volume: 10 mL; flow rate: 6 mL/s). Each dog was examined with each protocol. The interval between each computed tomography scan session which included 2 measurements was at least 3 days. Dynamic computed tomography scans were acquired at the level of the cephalic vein, cranial vena cava, pulmonary artery, and ascending and descending aorta. Time-enhancement curves were computed, and pulmonary and aortic peak enhancements as well as time-to-peak were analyzed. Increased saline chaser flow rates or increased saline chaser volumes resulted in increased pulmonary and aortic peak contrast enhancement. Peak enhancement was highest and significantly greater compared with no saline chaser for a flow rate of 8 mL/s (pulmonary artery: 816.8 vs. 471.5 HU, P = 0.0079; ascending aorta: 578.7 vs. 384.1 HU, P = 0.0079; descending aorta: 581.4 HU vs. 390.6 HU, P = 0.0159) and a saline volume of 15 mL (pulmonary artery: 670.2 vs. 453.5 HU, P = 0.0079; ascending aorta: 512.1 vs. 370.6 HU, P = 0.0317; descending aorta: 504.0 HU vs. 394.4 HU, P = 0.0159). No significant differences between the peak times for different saline chasers were

  15. On a sparse pressure-flow rate condensation of rigid circulation models.

    Science.gov (United States)

    Schiavazzi, D E; Hsia, T Y; Marsden, A L

    2016-07-26

    Cardiovascular simulation has shown potential value in clinical decision-making, providing a framework to assess changes in hemodynamics produced by physiological and surgical alterations. State-of-the-art predictions are provided by deterministic multiscale numerical approaches coupling 3D finite element Navier Stokes simulations to lumped parameter circulation models governed by ODEs. Development of next-generation stochastic multiscale models whose parameters can be learned from available clinical data under uncertainty constitutes a research challenge made more difficult by the high computational cost typically associated with the solution of these models. We present a methodology for constructing reduced representations that condense the behavior of 3D anatomical models using outlet pressure-flow polynomial surrogates, based on multiscale model solutions spanning several heart cycles. Relevance vector machine regression is compared with maximum likelihood estimation, showing that sparse pressure/flow rate approximations offer superior performance in producing working surrogate models to be included in lumped circulation networks. Sensitivities of outlets flow rates are also quantified through a Sobol׳ decomposition of their total variance encoded in the orthogonal polynomial expansion. Finally, we show that augmented lumped parameter models including the proposed surrogates accurately reproduce the response of multiscale models they were derived from. In particular, results are presented for models of the coronary circulation with closed loop boundary conditions and the abdominal aorta with open loop boundary conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Radiotherapy Reduced Salivary Flow Rate and Might Induced C. albicans Infection

    Directory of Open Access Journals (Sweden)

    Nadia Surjadi

    2013-07-01

    Full Text Available Radiotherapy has impact in oral health especially on the secretion capacity of the salivary glands. Another impact is the increase of Candida albicans colony. Objectives: To evaluate salivary flow in relation with Candida albicans colony in head and neck cancer patients during and after radiotherapy. Methods: Twenty-four head and neck cancer patients in Dharmais Cancer Hospital, Jakarta who were undergoing radiotherapy or had undergone radiotherapy and 24 match healthy volunteers were included in the study. Clinical observation carried out by collecting unstimulated salivary flow rate and followed by culture of Candida in Saboraud agar medium. Data were analyzed statistically by Chi-square. Results: Nasopharynx cancer was the most frequent type of head and neck cancers (87.5% followed by tongue cancer (12.5% and and found in 41-50 years old patients and 51-60 years old patients respectively, with male predilection compare to female (17:7. Approxiamtely 87.5% of subjects showed decreased salivary flow rate (1.01-1.50mL/10min during and after radiotherapy. However, 91.7% of cancer patients had increased C.albicans colony during and after radiotherapy compared to control (p=0.00. Conclusion: This study showed that radiotherapy induced hyposalivation and might increase the C.albicans colony.  

  17. New approach to purging monitoring wells: Lower flow rates reduce required purging volumes and sample turbidity

    Energy Technology Data Exchange (ETDEWEB)

    Puls, R.W.

    1994-01-01

    It is generally accepted that monitoring wells must be purged to access formation water to obtain representative' ground water quality samples. Historically anywhere from 3 to 5 well casing volumes have been removed prior to sample collection to evacuate the standing well water and access the adjacent formation water. However, a common result of such purging practice is highly turbid samples from excessive downhole disturbance to the sampling zone. An alternative purging strategy has been proposed using pumps which permit much lower flow rates (<1 liter/min) and placement within the screened interval of the monitoring well. The advantages of this approach include increased spatial resolution of sampling points, less variability, less purge time (and volume), and low-turbidity samples. The overall objective is a more passive approach to sample extraction with the ideal approach being to match the intake velocity with the natural ground water flow velocity. The volume of water extracted to access formation water is generally independent of well size and capacity and dependant upon well construction, development, hydrogeologic variability and pump flow rate.

  18. Measurement of pulp blood flow rates in maxillary anterior teeth using ultrasound Doppler flowmetry.

    Science.gov (United States)

    Cho, Y-W; Park, S-H

    2015-12-01

    To measure pulp blood flow rates of clinically normal maxillary anterior teeth of healthy adults using ultrasound Doppler flowmetry (UDF). A total of 359 anterior teeth from 63 patients (mean age, 29.8 years; range, 22-52 years; 26 females and 36 males) were included. The data were collected according to tooth type (three groups: central incisors, lateral incisors and canines). An MM-D-K (Minimax, Moscow, Russia) ultrasound Doppler imaging instrument was used to measure pulp blood flow. Differences between the tooth types were analysed with one-way anova and a Bonferroni correction at the 95% confidence level. The mean average linear velocities during the systolic period (Vams) of the central incisors, lateral incisors and canines were 0.58, 0.58 and 0.52 cm s(-1) , respectively. There were no significant differences in the mean Vams between the tooth types (P > 0.05). Within the limitations of this study, the pulp blood velocities of clinically normal, maxillary anterior teeth of healthy adults were between 0.5 and 0.6 cm s(-1) . There were no significant differences in mean blood flow rates between maxillary central incisors, lateral incisors and canines. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  19. Decomposition behavior of hemicellulose and lignin in the step-change flow rate liquid hot water.

    Science.gov (United States)

    Zhuang, Xinshu; Yu, Qiang; Wang, Wen; Qi, Wei; Wang, Qiong; Tan, Xuesong; Yuan, Zhenhong

    2012-09-01

    Hemicellulose and lignin are the main factors limiting accessibility of hydrolytic enzymes besides the crystallinity of cellulose. The decomposition behavior of hemicellulose and lignin in the step-change flow rate hot water system was investigated. Xylan removal increased from 64.53% for batch system (solid concentration 4.25% w/v, 18 min, 184°C) to 83.78% at high flow rates of 30 ml/min for 8 min, and then 10 ml/min for 10 min. Most of them (80-90%) were recovered as oligosaccharide. It was hypothesized that the flowing water could enhance the mass transfer to improve the sugars recovery. In addition, the solubilization mechanism of lignin in the liquid hot water was proposed according to the results of Fourier transform-infrared spectroscopy and scanning electron microscopy of the water-insoluble fraction and gas chromatography-mass spectrometry of the water-soluble fraction. It was proposed that lignin in the liquid hot water first migrated out of the cell wall in the form of molten bodies, and then flushed out of the reactor. A small quantity of them was further degraded into monomeric products such as vanillin, syringe aldehyde, coniferyl aldehyde, ferulic acid, and p-hydroxy-cinnamic acid. All of these observations would provide important information for the downstream processing, such as purification and concentration of sugars and the enzymatic digestion of residual solid.

  20. Multiple flow rates measurement of exhaled nitric oxide in patients with sarcoidosis: a pilot feasibility study.

    Science.gov (United States)

    Choi, J; Hoffman, L A; Sethi, J M; Zullo, T G; Gibson, K F

    2009-07-01

    Fraction of end tidal exhaled nitric oxide (FeNO) has been introduced as a non-invasive marker of airway inflammation in patients with asthma and may have value in monitoring disease activity in patients with sarcoidosis. This pilot study explored: 1) feasibility of the multiple flow rates maneuver to estimate alveolar (C(AlV)NO) and airway wall (J(AW)NO) NO in patients with sarcoidosis; and 2) utility of exhaled NO (FeNO, C(Alv)NO and J(AW)NO) measurements to detect and monitor treatment response in patients with active pulmonary sarcoidosis. Patients with sarcoidosis (n = 42) and healthy non-smokers (n = 20) underwent FeNO measurement at 7 flow-rates (50 to 400 ml/s). Using the Tsoukias and George (1998) model, C(Alv)NO and J(AW)NO were estimated. Both patients and healthy non-smokers were able to perform the multiple flow rates maneuver without discomfort, with first measurement success rate of 57% and 65%, respectively. No significant difference was found between patients with sarcoidosis and healthy non-smokers in exhaled NO. None were correlated with pulmonary function tests, except a significant negative correlation between C(Alv)NO and FVC% (p = 0.001) and DLCO% (p = 0.012). In 8 patients with active sarcoidosis, FeNO, C(Alv)NO or J(AW)NO were not different from those of patients with inactive sarcoidosis. Treatment of active sarcoidosis using oral prednisone and methotrexate did not show any consistent pattern of changes in C(Alv)NO or J(AW)NO. Due to a large inter-subject variability and difficulty controlling use of the inhaled corticosteroids, exhaled NO measurement did not appear to be a clinically useful method of monitoring disease progression in sarcoidosis.

  1. Measuring the orientation and rotation rate of 3D printed particles in turbulent flow

    Science.gov (United States)

    Voth, Greg; Kramel, Stefan; Cole, Brendan

    2015-03-01

    The orientation distribution and rotations of anisotropic particles plays a key role in many applications ranging from icy clouds to papermaking and drag reduction in pipe flow. Experimental access to time resolved orientations of anisotropic particles has not been easy to achieve. We have found that 3D printing technology can be used to fabricate a wide range of particle shapes with smallest dimension down to 300 ?m. So far we have studied rods, crosses, jacks, tetrads, and helical shapes. We extract the particle orientations from stereoscopic video images using a method of least squares optimization in Euler angle space. We find that in turbulence the orientation and rotation rate of many particles can be understood using a simple picture of alignment of both the vorticity and a long axis of the particle with the Lagrangian stretching direction of the flow.

  2. The Effect of Personality on Online Game Flow Experience and the Eye Blink Rate as an Objective Indicator

    Directory of Open Access Journals (Sweden)

    Pei-Luen Patrick Rau

    2017-01-01

    Full Text Available This study aimed to explore the effects of dominant and compliant personalities, on both flow experience and the external characteristics of flow experience. A total of 48 participants were recruited to play an online game and subsequently asked to recall the songs they had heard while they were playing the game. Eye blink rate was recorded. The results demonstrated that (1 the participant was immersed in the game more if he/she was relatively dominant or noncompliant; (2 the perceptions about the external environment declined remarkably while being in a flow state; and (3 eye blink rates decreased only when the flow happened at the beginning of the game, rather than throughout the whole process. The results suggested that gamers who tend to be dominant or noncompliant were more likely to experience flow. Eye blink rate and perceptions of the external environment could be objective indicators of flow experience.

  3. High rates of gene flow by pollen and seed in oak populations across Europe.

    Directory of Open Access Journals (Sweden)

    Sophie Gerber

    Full Text Available Gene flow is a key factor in the evolution of species, influencing effective population size, hybridisation and local adaptation. We analysed local gene flow in eight stands of white oak (mostly Quercus petraea and Q. robur, but also Q. pubescens and Q. faginea distributed across Europe. Adult trees within a given area in each stand were exhaustively sampled (range [239, 754], mean 423, mapped, and acorns were collected ([17,147], 51 from several mother trees ([3], [47], 23. Seedlings ([65,387], 178 were harvested and geo-referenced in six of the eight stands. Genetic information was obtained from screening distinct molecular markers spread across the genome, genotyping each tree, acorn or seedling. All samples were thus genotyped at 5-8 nuclear microsatellite loci. Fathers/parents were assigned to acorns and seedlings using likelihood methods. Mating success of male and female parents, pollen and seed dispersal curves, and also hybridisation rates were estimated in each stand and compared on a continental scale. On average, the percentage of the wind-borne pollen from outside the stand was 60%, with large variation among stands (21-88%. Mean seed immigration into the stand was 40%, a high value for oaks that are generally considered to have limited seed dispersal. However, this estimate varied greatly among stands (20-66%. Gene flow was mostly intraspecific, with large variation, as some trees and stands showed particularly high rates of hybridisation. Our results show that mating success was unevenly distributed among trees. The high levels of gene flow suggest that geographically remote oak stands are unlikely to be genetically isolated, questioning the static definition of gene reserves and seed stands.

  4. Maximizing protein translation rate in the non-homogeneous ribosome flow model: a convex optimization approach.

    Science.gov (United States)

    Poker, Gilad; Zarai, Yoram; Margaliot, Michael; Tuller, Tamir

    2014-11-06

    Translation is an important stage in gene expression. During this stage, macro-molecules called ribosomes travel along the mRNA strand linking amino acids together in a specific order to create a functioning protein. An important question, related to many biomedical disciplines, is how to maximize protein production. Indeed, translation is known to be one of the most energy-consuming processes in the cell, and it is natural to assume that evolution shaped this process so that it maximizes the protein production rate. If this is indeed so then one can estimate various parameters of the translation machinery by solving an appropriate mathematical optimization problem. The same problem also arises in the context of synthetic biology, namely, re-engineer heterologous genes in order to maximize their translation rate in a host organism. We consider the problem of maximizing the protein production rate using a computational model for translation-elongation called the ribosome flow model (RFM). This model describes the flow of the ribosomes along an mRNA chain of length n using a set of n first-order nonlinear ordinary differential equations. It also includes n + 1 positive parameters: the ribosomal initiation rate into the mRNA chain, and n elongation rates along the chain sites. We show that the steady-state translation rate in the RFM is a strictly concave function of its parameters. This means that the problem of maximizing the translation rate under a suitable constraint always admits a unique solution, and that this solution can be determined using highly efficient algorithms for solving convex optimization problems even for large values of n. Furthermore, our analysis shows that the optimal translation rate can be computed based only on the optimal initiation rate and the elongation rate of the codons near the beginning of the ORF. We discuss some applications of the theoretical results to synthetic biology, molecular evolution, and functional genomics. © 2014 The

  5. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    Science.gov (United States)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    ablation. Two different ablation models are proposed to determine the heat loss from the solid surface due to the ablation of the solid material. Both of them are physics based. Various numerical simulations were carried out using both models to predict the temperature distribution in the solid and in the gas flow, and then predict the ablation rates at a typical NTR motor hydrogen gas temperature and pressure. Solid mass loss rate per foot of a pipe was also calculated from these predictions. The results are presented for fully developed turbulent flow conditions in a sample SS pipe with a 6 inch diameter.

  6. Flow rate analysis of wastewater inside reactor tanks on tofu wastewater treatment plant

    Science.gov (United States)

    Mamat; Sintawardani, N.; Astuti, J. T.; Nilawati, D.; Wulan, D. R.; Muchlis; Sriwuryandari, L.; Sembiring, T.; Jern, N. W.

    2017-03-01

    The research aimed to analyse the flow rate of the wastewater inside reactor tanks which were placed a number of bamboo cutting. The resistance of wastewater flow inside reactor tanks might not be occurred and produce biogas fuel optimally. Wastewater from eleven tofu factories was treated by multi-stages anaerobic process to reduce its organic pollutant and produce biogas. Biogas plant has six reactor tanks of which its capacity for waste water and gas dome was 18 m3 and 4.5 m3, respectively. Wastewater was pumped from collecting ponds to reactors by either serial or parallel way. Maximum pump capacity, head, and electrical motor power was 5m3/h, 50m, and 0.75HP, consecutively. Maximum pressure of biogas inside the reactor tanks was 55 mbar higher than atmosphere pressure. A number of 1,400 pieces of cutting bamboo at 50-60 mm diameter and 100 mm length were used as bacteria growth media inside each reactor tank, covering around 14,287 m2 bamboo area, and cross section area of inner reactor was 4,9 m2. In each reactor, a 6 inches PVC pipe was installed vertically as channel. When channels inside reactor were opened, flow rate of wastewater was 6x10-1 L.sec-1. Contrary, when channels were closed on the upper part, wastewater flow inside the first reactor affected and increased gas dome. Initially, wastewater flowed into each reactor by a gravity mode with head difference between the second and third reactor was 15x10-2m. However, head loss at the second reactor was equal to the third reactor by 8,422 x 10-4m. As result, wastewater flow at the second and third reactors were stagnant. To overcome the problem pump in each reactor should be installed in serial mode. In order to reach the output from the first reactor and the others would be equal, and biogas space was not filled by wastewater, therefore biogas production will be optimum.

  7. Determination of rapid chlorination rate constants by a stopped-flow spectrophotometric competition kinetics method.

    Science.gov (United States)

    Song, Dean; Liu, Huijuan; Qiang, Zhimin; Qu, Jiuhui

    2014-05-15

    Free chlorine is extensively used for water and wastewater disinfection nowadays. However, it still remains a big challenge to determine the rate constants of rapid chlorination reactions although competition kinetics and stopped-flow spectrophotometric (SFS) methods have been employed individually to investigate fast reaction kinetics. In this work, we proposed an SFS competition kinetics method to determine the rapid chlorination rate constants by using a common colorimetric reagent, N,N-diethyl-p-phenylenediamine (DPD), as a reference probe. A kinetic equation was first derived to estimate the reaction rate constant of DPD towards chlorine under a given pH and temperature condition. Then, on that basis, an SFS competition kinetics method was proposed to determine directly the chlorination rate constants of several representative compounds including tetracycline, ammonia, and four α-amino acids. Although Cl2O is more reactive than HOCl, its contribution to the overall chlorination kinetics of the test compounds could be neglected in this study. Finally, the developed method was validated through comparing the experimentally measured chlorination rate constants of the selected compounds with those obtained or calculated from literature and analyzing with Taft's correlation as well. This study demonstrates that the SFS competition kinetics method can measure the chlorination rate constants of a test compound rapidly and accurately. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Food loss rate in food supply chain using material flow analysis.

    Science.gov (United States)

    Ju, Munsol; Osako, Masahiro; Harashina, Sachihiko

    2017-03-01

    The food loss rate is a factor that represents food consumption efficiency. To improve food consumption efficiency, we need to fundamentally quantify food loss at national and global levels. This study examines food and food waste flow and calculates the food loss rate in the food supply chain by targeting Japan. We analyzed inedible food waste and avoidable food losses in wholesale, manufacturing, retail, food services, and households and considered different supply chain pathways, different food categories representing whole Japanese meals, and weight changes after cooking. The results are as follows: (1) Japan has an overall rate of avoidable food losses of approximately 15% for meals (excluding agricultural losses), (2) the supply sector with the highest food loss rate is food services, and (3) the food category with the highest food loss rate is vegetables. Finally, we proposed a model for calculating food loss rates that could be used for future analysis in Japan or other countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

  10. Net capital flows to and the real exchange rate of Western Balkan countries

    Directory of Open Access Journals (Sweden)

    Gabrisch Hubert

    2015-01-01

    Full Text Available This paper uses Granger causality tests to assess the linkages between changes in the real exchange rate and net capital inflows using the example of Western Balkan countries, which have suffered from low competitiveness and external imbalances for many years. The real exchange rate is a measure of a country’s price competitiveness, and the paper uses two concepts: relative unit labour cost and relative inflation differential. The sample consists of six Western Balkan countries for the period 1996-2012, relative to the European Union (EU. The main finding is that changes in the net capital flows precede changes in relative unit labour costs and not vice versa. Also, there is evidence that net capital flows affect the inflation differential of countries, although to a less discernible extent. This suggests that the increasing divergence in the unit labour cost between the EU and Western Balkan countries up to the global financial crisis was at least partly the result of net capital inflows. The paper adds to the ongoing debate on improving cost competitiveness through wage restrictions as the main vehicle to avert the accumulation of current account imbalances. It shows the importance of changes in the exchange rate regime, reform of the interaction between the financial and the real sector, and financial supervision and structural change.

  11. Vertical multiphase flow correlations for high production rates and large tubulars

    Energy Technology Data Exchange (ETDEWEB)

    Aggour, M.A.; Al-Yousef, H.Y. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Muraikhi, A.J.

    1996-02-01

    Numerous correlations exist for predicting pressure drop in vertical multiphase flow. These correlations, however, were all developed and tested under limited operating conditions that do not match the high production rates and large tubulars normally found in the Middle East fields. This paper presents a comprehensive evaluation of existing correlations and modifications of some correlations to determine and recommend the best correlation or correlations for various field conditions. More than 400 field data sets covering tubing sizes from 2 3/8 to 7 inches, oil rates up to 23,200 B/D, water cuts up to 95%, and gas/oil ratio (GOR) up to 927 scf/STB were used in this study. Considering all data combined, the Beggs and Brill correlation provided the best pressure predictions. However, the Hagedorn and Brown correlation was better for water cuts above 80%, while the Hasan and Kabir model was better for total liquid rates above 20,000 B/D. The Aziz correlation was significantly improved when the Orkiszewski flow-pattern transition criteria were used.

  12. Monitoring nano-flow rate of water by atomic emission detection using helium radio-frequency plasma.

    Science.gov (United States)

    Nakagama, Tatsuro; Maeda, Tsuneaki; Uchiyama, Katsumi; Hobo, Toshiyuki

    2003-06-01

    Recently, high-performance nano-scale flow pumping systems have been developed for micro and miniaturized analysis systems. A novel device capable of measuring and monitoring nanoliter scale flow rates has been required for the further development of the pumping system. In this study, an atomic emission detector using helium radio-frequency plasma (RFP-AED) was used for the measurement of the nanoliter scale flow rate of water by quantitatively detecting the emission from hydrogen in the water molecules. Monitoring nano-flow rates of water in the range up to 1.0 microl min(-1), and the change in the flow rate by the indication of the ratio of the emissions of H (656.3 nm) and He (667.8 nm) were successful. At present, the lowest flow rate that could be determined reproducibly was 4 nl min(-1) calculated as five times the standard deviation of the background noise. Additionally, similar evaluations for the deviation of each flow rate by using the RFP-AED and a flow-injection system were produced.

  13. Effects of Chewing Different Flavored Gums on Salivary Flow Rate and pH

    Directory of Open Access Journals (Sweden)

    Maryam Karami Nogourani

    2012-01-01

    Full Text Available Chewing gum increases salivary flow rate (SFR and pH, but differences in preferences of gum flavor may influence SFR and pH. The aim of this paper was to assess the effect of five different flavors of sucrose-free chewing gum on the salivary flow rate and pH in healthy dental students in Isfahan, Iran. Fifteen (7 men and 8 women healthy dental student volunteers collected unstimulated saliva and then chewed one of five flavored gums for 6 min. The whole saliva was collected and assessed for 6 consecutive days. After unstimulated saliva was collected, stimulated saliva was collected at interval of 0-1, 1–3, and 3–6 minutes after the start of different flavored chewing gums. The SFR and salivary pH were measured. The SFR increased in all five flavored gums at 1, 3, and 6 minutes after start of chewing gums (<0.001. The flow rate of all products reached peak in the 1st minute of stimulation, except spearmint-flavored gums which reached peak in the 6th minute. In the 1st minute, the strawberry-flavored gums showed the highest SFR. During 1–3 minutes, strawberry- and apple-flavored gums showed higher SFR, respectively. Only the spearmint- and cinnamon-flavored gum significantly increased salivary pH. Gum flavored can affect the SFR and pH and special flavors can be advised for different individuals according to their oral conditions.

  14. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease.

    Science.gov (United States)

    Nozoe, Masafumi; Mase, Kyoshi; Ogino, Tomoyuki; Murakami, Shigefumi; Takashima, Sachie; Domen, Kazuhisa

    2016-03-15

    Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Fourteen subjects were recruited from among patients with COPD who were receiving pulmonary rehabilitation at the University Hospital (COPD group). Fourteen age-matched healthy subjects were also consecutively recruited from the local community (Healthy control group). Airflow and lung volume changes were measured continuously with the subjects lying in supine position during 1 minute of quiet breathing (QB) and during 1 minute of CWC by a physical therapist. During CWC, both the COPD group and the healthy control group showed significantly higher peak expiratory flow rates (PEFRs) than during QB (mean difference for COPD group 0.14 L/sec, 95% confidence interval (CI) 0.04 to 0.24, pCOPD group (-0.25 L/sec, 95% CI -0.43 to -0.07, pCOPD group (0.05 L/sec, 95% CI -0.01 to 0.12: -0.01 L/sec, 95% CI -0.11 to 0.08: 0.02 L/sec, 95% CI -0.05 to 0.90) with the application of CWC. The effects of chest wall compression on expiratory flow rates was different between COPD patients and asymptomatic controls.

  15. Peak expiratory flow rate in healthy children aged 6-17 years

    DEFF Research Database (Denmark)

    Høst, A; Høst, A H; Ibsen, T

    1994-01-01

    Peak expiratory flow rate (PEFR) was measured in a cross-sectional study in 861 healthy Danish schoolchildren aged 6-17 years using a Mini Wright peak flowmeter. We found a strong correlation between PEFR and height, age and sex. The results were comparable with those from previous studies using...... a Wright peak flowmeter. The equation for prediction of PEFR in boys was calculated as (3.8 x height) + (10.6 x age) - 313.2 (p age) - 143.9 (p

  16. A differential equation for the flow rate during silo discharge: Beyond the Beverloo rule

    Directory of Open Access Journals (Sweden)

    Madrid Marcos A.

    2017-01-01

    Full Text Available We present a differential equation for the flow rate of granular materials during the discharge of a silo. This is based in the energy balance of the variable mass system in contrast with the traditional derivations based on heuristic postulates such as the free fall arch. We show that this new equation is consistent with the well known Beverloo rule, providing an independent estimate for the universal Beverloo prefactor. We also find an analytic expression for the pressure under discharging conditions.

  17. Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

    Directory of Open Access Journals (Sweden)

    Rousse Maria G

    2011-04-01

    Full Text Available Abstract Background The determination of coronary flow reserve (CFR is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD coronary artery. Methods A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography. Results The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%. Mean CFR was 2.67 at de end of dobutamine test. There was an excellent concordance between delta HR (difference between baseline HR and maximum HR and the increase in the CFR (correlation coefficient 0.84. In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%. In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99% at 75% of their predicted maximum heart rate. Conclusions We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm

  18. Accurate Angle Estimator for High-Frame-rate 2-D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Lindskov Hansen, Kristoffer

    2016-01-01

    This paper presents a novel approach for estimating 2-D flow angles using a high-frame-rate ultrasound method. The angle estimator features high accuracy and low standard deviation (SD) over the full 360° range. The method is validated on Field II simulations and phantom measurements using the ex...... measurement is performed on a carotid bifurcation of a healthy individual. A 3-s acquisition during three heart cycles is captured. A consistent and repetitive vortex is observed in the carotid bulb during systoles....

  19. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Masafumi Nozoe

    2016-01-01

    Full Text Available Background: Manual chest wall compression (CWC during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD. Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receiving pulmonary rehabilitation at the University Hospital (COPD group. Fourteen age-matched healthy subjects were also consecutively recruited from the local community (Healthy control group. Airflow and lung volume changes were measured continuously with the subjects lying in supine position during 1 minute of quiet breathing (QB and during 1 minute of CWC by a physical therapist. Results: During CWC, both the COPD group and the healthy control group showed significantly higher peak expiratory flow rates (PEFRs than during QB (mean difference for COPD group 0.14 L/sec, 95% confidence interval (CI 0.04 to 0.24, p<0.01, mean difference for healthy control group 0.39 L/sec, 95% CI 0.25 to 0.57, p<0.01. In the between-group comparisons, PEFR was significantly higher in the healthy control group than in the COPD group (-0.25 L/sec, 95% CI -0.43 to -0.07, p<0.01. However, the expiratory flow rates at the lung volume at the PEFR during QB and at 50% and 25% of tidal volume during QB increased in the healthy control group (mean difference for healthy control group 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.27 L/sec, 95% CI 0.13 to 0.41, p<0.01, respectively but not in the COPD group (0.05 L/sec, 95% CI -0.01 to 0.12: -0.01 L/sec, 95% CI -0.11 to 0.08: 0.02 L/sec, 95% CI -0.05 to 0.90 with the application of CWC. Conclusion: The effects of chest wall compression on expiratory flow rates was different between COPD patients and

  20. Is peak expiratory flow rate a predictor of complications in diabetes? The Wisconsin Epidemiologic Study of Diabetic Retinopathy.

    Science.gov (United States)

    Klein, B E; Moss, S E; Klein, R; Cruickshanks, K J

    2001-01-01

    The Objective of this study was to determine whether peak expiratory flow rate is a predictor of complications of diabetes. Peak expiratory flow rate was measured at the 10-year follow-up (third examination) of a cohort of persons with younger-onset diabetes. The relationships of progression of diabetic retinopathy by two steps, progression to proliferative retinopathy and of incidences of macular edema, sore or ulcers on feet or ankles, lower extremity amputation, proteinuria, and cardiovascular disease 4 years after this examination with respect to peak expiratory flow rate were evaluated. Study procedures including measurements of blood pressure, height and weight, grading of fundus photographs, peak expiratory flow rate, urinalysis, and medical history were performed according to standard protocols. Peak expiratory flow rate was not associated in univariate analyses with progression of retinopathy, incidences of proliferative retinopathy, macular edema or lower extremity amputation, sores or ulcers on feet or ankles, gross proteinuria, or self-reported cardiovascular disease. However, when using multivariable models to include the effects of other risk factors, peak expiratory flow rate was significantly associated with the combined incidences of sores or ulcers on feet and ankles, or lower extremity amputations (OR=0.61, 95% CI 0.42-0.88). These data suggest that peak expiratory flow rate is a predictor of subsequent complications in the lower extremities in those with long duration of younger-onset diabetes. Evaluating this association in an incipient cohort would illuminate whether the relationship we found is likely to be causal.

  1. 40 CFR Table 1 to Subpart Rrrr of... - Operating Limits if Using the Emission Rate With Add-on Controls Option

    Science.gov (United States)

    2010-07-01

    ... Rate With Add-on Controls Option 1 Table 1 to Subpart RRRR of Part 63 Protection of Environment... Limits if Using the Emission Rate With Add-on Controls Option If you are required to comply with... volumetric flow rate or duct static pressure in each duct between a capture device and add-on control device...

  2. Evaluation of In Vitro and In Vivo Flow Rate Dependency of Budesonide/Formoterol Easyhaler®

    Science.gov (United States)

    Malmberg, L. Pekka; Everard, Mark L.; Haikarainen, Jussi

    2014-01-01

    Abstract Background: The Easyhaler® (EH) device-metered dry powder inhaler containing budesonide and formoterol is being developed for asthma and chronic obstructive pulmonary disease (COPD). As a part of product optimization, a series of in vitro and in vivo studies on flow rate dependency were carried out. Methods: Inspiratory flow parameters via EH and Symbicort® Turbuhaler® (TH) inhalers were evaluated in 187 patients with asthma and COPD. The 10th, 50th, and 90th percentile flow rates achieved by patients were utilized to study in vitro flow rate dependency of budesonide/formoterol EH and Symbicort TH. In addition, an exploratory pharmacokinetic study on pulmonary deposition of active substances for budesonide/formoterol EH in healthy volunteers was performed. Results: Mean inspiratory flow rates through EH were 64 and 56 L/min in asthmatics and COPD patients, and through TH 79 and 72 L/min, respectively. Children with asthma had marginally lower PIF values than the adults. The inspiratory volumes were similar in all groups between the inhalers. Using weighted 10th, 50th, and 90th percentile flows the in vitro delivered doses (DDs) and fine particle doses (FPDs) for EH were rather independent of flow as 98% of the median flow DDs and 89%–93% of FPDs were delivered already at 10th percentile air flow. Using±15% limits, EH and TH had similar flow rate dependency profiles between 10th and 90th percentile flows. The pharmacokinetic study with budesonide/formoterol EH in healthy subjects (n=16) revealed a trend for a flow-dependent increase in lung deposition for both budesonide and formoterol. Conclusions: Comparable in vitro flow rate dependency between budesonide/formoterol EH and Symbicort TH was found using the range of clinically relevant flow rates. The results of the pharmacokinetic study were in accordance with the in vitro results showing only a trend of flow rate-dependant increase in lung deposition of active substances with EH. PMID:24978441

  3. Long-term flow-through column experiments and their relevance to natural granitoid weathering rates

    Science.gov (United States)

    White, Art F.; Schulz, Marjorie S.; Lawrence, Corey R.; Vivit, Davison V.; Stonestrom, David A.

    2017-04-01

    Four pairs of fresh and partly-weathered granitoids, obtained from well-characterized watersheds-Merced River, CA, USA; Panola, GA, USA; Loch Vale, CO, USA, and Rio Icacos, Puerto Rico-were reacted in columns under ambient laboratory conditions for 13.8 yrs, the longest running experimental weathering study to date. Low total column mass losses (surface roughening of primary silicate grains. BET surface area (SBET) increased, primarily due to Fe-oxyhydroxide precipitation. Surface areas returned to within factors of 2-3 of their original values after dithionite extraction. Miscible displacement experiments indicated homogeneous plug flow with negligible immobile water, commonly cited for column experiments. Fresh granitoid effluent solute concentrations initially declined rapidly, followed by much slower decreases over the next decade. Weathered granitoid effluent concentrations increased modestly over the same time period, indicating losses of natural Fe-oxide and/or clay coatings and the increased exposure of primary mineral surfaces. Corresponding (fresh and weathered) elemental effluent concentrations trended toward convergence during the last decade of reaction. NETPATH/PHREEQC code simulations indicated non-stoichiometric dissolution involving Ca release from disseminated calcite and excess K release from interlayer biotite. Effluent 87Sr/85Sr ratios reflected a progressive weathering sequence beginning and ending with 87Sr/85Sr values of plagioclase with an additional calcite input and a radiogenic biotite excursion proportional to the granitoid ages. Effluents became thermodynamically saturated with goethite and gibbsite, slightly under-saturated with kaolinite and strongly under-saturated with plagioclase, consistent with kinetically-limited weathering in which solutes such as Na varied with column flow rates. Effluent Na concentrations showed no clear trend with time during the last decade of reaction (fresh granitoids) or increased slowly with time

  4. 222Rn concentrations, natural flow rate and the radiation exposure levels in the Nerja Cave

    Science.gov (United States)

    Dueñas, C.; Fernández, M. C.; Cañete, S.; Carretero, J.; Liger, E.

    222Rn concentrations in the air in Nerja Cave (Spain) have been measured over 4 yr and at four sampling points. Concentrations average 168 Bq m -3 in the spring-summer when the temperature lapse rate provides a stable cave atmosphere. In the autumn-winter, the radon levels decrease to 48 Bq m -3. 222Rn flux has also been measured for soils in the cave, with an average value of 34 × 10 -3 Bq m -2 s -1. The average natural flow rate in the spring-summer is about 0.70 m 3 s -1 and the autumn-winter is approximately 3.6 m 3 s -1 determined over 1992-1995. The radiation exposure levels for workers and tourists represent only a low percentage of the exposure guides for the general population.

  5. Process conditions and volumetric composition in composites

    DEFF Research Database (Denmark)

    Madsen, Bo

    2013-01-01

    The obtainable volumetric composition in composites is linked to the gravimetric composition, and it is influenced by the conditions of the manufacturing process. A model for the volumetric composition is presented, where the volume fractions of fibers, matrix and porosity are calculated as a fun......The obtainable volumetric composition in composites is linked to the gravimetric composition, and it is influenced by the conditions of the manufacturing process. A model for the volumetric composition is presented, where the volume fractions of fibers, matrix and porosity are calculated...

  6. Effects of air flow rate, storage temperature, and harvest maturity on respiration and ripening of tomato fruits.

    Science.gov (United States)

    Pharr, D M; Kattan, A A

    1971-07-01

    The interactive effects of aeration rate, storage temperature, harvest maturity, and storage duration on respiration and ripening of tomato fruits (Lycopersicum esculentum var. Roma) were studied. Slow aeration rate strongly reduced the climacteric but did not affect ripening. Low temperature slowed ripening and reduced respiratory rates, but low temperature did not delay attainment of the climacteric maxima. The effect of air flow rate on the content of CO(2) in the fruits' internal atmospheres was investigated. The possibility that CO(2) is not the primary cause of respiratory inhibition under slow air flow rate is discussed.

  7. Study of Low Flow Rate Ladle Bottom Gas Stirring Using Triaxial Vibration Signals

    Science.gov (United States)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle; Li, Zushu; Goodwin, Tim

    2018-02-01

    Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

  8. Effect of Long-term Smoking on Whole-mouth Salivary Flow Rate and Oral Health.

    Science.gov (United States)

    Rad, Maryam; Kakoie, Shahla; Niliye Brojeni, Fateme; Pourdamghan, Nasim

    2010-01-01

    Change in the resting whole-mouth salivary flow rate (SFR) plays a significant role in patho-genesis of various oral conditions. Factors such as smoking may affect SFR as well as the oral and dental health. The primary purpose of this study was to determine the effect of smoking on SFR, and oral and dental health. One-hundred smokers and 100 non-tobacco users were selected as case and control groups, respectively. A questionnaire was used to collect the demographic data and smoking habits. A previously used questionnaire about dry mouth was also employed. Then, after a careful oral examination, subjects' whole saliva was collected in the resting condition. Data was analyzed by chi-square test using SPSS 15. The mean (±SD) salivary flow rate were 0.38 (± 0.13) ml/min in smokers and 0.56 (± 0.16) ml/min in non-smokers. The difference was statistically significant (P=0.00001). Also, 39% of smokers and 12% of non-smokers reported experiencing at least one xerostomia symptom, with statistically significant difference between groups (p=0.0001). Oral lesions including cervical caries, gingivitis, tooth mobility, calculus and halitosis were significantly higher in smokers. Our findings indicated that long-term smoking would significantly reduce SFR and increase oral and dental disorders associated with dry mouth, especially cervical caries, gingivitis, tooth mobility, calculus, and halitosis.

  9. Influences of gender and anthropometric features on inspiratory inhaler acoustics and peak inspiratory flow rate.

    Science.gov (United States)

    Taylor, Terence E; Holmes, Martin S; Sulaiman, Imran; Costello, Richard W; Reilly, Richard B

    2015-01-01

    Inhalers are hand-held devices used to treat chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Medication is delivered from an inhaler to the user through an inhalation maneuver. It is unclear whether gender and anthropometric features such as age, height, weight and body mass index (BMI) influence the acoustic properties of inspiratory inhaler sounds and peak inspiratory flow rate (PIFR) in inhalers. In this study, healthy male (n=9) and female (n=7) participants were asked to inhale at an inspiratory flow rate (IFR) of 60 L/min in four commonly used inhalers (Turbuhaler(™), Diskus(™), Ellipta(™) and Evohaler(™)). Ambient inspiratory sounds were recorded from the mouthpiece of each inhaler and over the trachea of each participant. Each participant's PIFR was also recorded for each of the four inhalers. Results showed that gender and anthropometric features have the potential to influence the spectral properties of ambient and tracheal inspiratory inhaler sounds. It was also observed that males achieved statistically significantly higher PIFRs in each inhaler in comparison to females (p<;0.05). Acoustic features were found to be significantly different across inhalers suggesting that acoustic features are modulated by the inhaler design and its internal resistance to airflow.

  10. Stimulated Hyposalivary Flow Rates in Healthcare Students in an Interprofessional Awareness Educational Program Curriculum

    Directory of Open Access Journals (Sweden)

    R. Constance Wiener

    2017-01-01

    Full Text Available Purpose. Hyposalivation influences quality of life and medication compliance. However, oral health knowledge (in general and knowledge about hyposalivation (in particular are often lacking in nondental healthcare professional’s curricula. Additionally, hyposalivation has not been adequately studied in young adults. The purpose for this study is twofold: to use an interprofessional educational curriculum to increase nondental healthcare students’ knowledge about oral health and salivary testing and determine whether hyposalivation is different between sexes in young adults. Method. First-year medical and pharmacy students (N=178 learned the process of saliva collection and provided samples in an interprofessional program. Results. There were 14.4% of participants with hyposalivation; 72.0% were female. Males had higher flow rates (P=0.005. There failed to be a significant difference between the sexes with frank hyposalivation. There failed to be a significant difference in hyposalivation and medication use/nonuse. Conclusions. Hyposalivation is a biomedical, public health concern. However, in this young population, there was no significant difference between sexes or in medication use/nonuse. Through participation in the program, the students learned about salivary flow rates and the need for collaboration among professionals to prevent negative impacts of hyposalivation and oral health.

  11. Flow Rates Measurement and Uncertainty Analysis in Multiple-Zone Water-Injection Wells from Fluid Temperature Profiles.

    Science.gov (United States)

    Reges, José E O; Salazar, A O; Maitelli, Carla W S P; Carvalho, Lucas G; Britto, Ursula J B

    2016-07-13

    This work is a contribution to the development of flow sensors in the oil and gas industry. It presents a methodology to measure the flow rates into multiple-zone water-injection wells from fluid temperature profiles and estimate the measurement uncertainty. First, a method to iteratively calculate the zonal flow rates using the Ramey (exponential) model was described. Next, this model was linearized to perform an uncertainty analysis. Then, a computer program to calculate the injected flow rates from experimental temperature profiles was developed. In the experimental part, a fluid temperature profile from a dual-zone water-injection well located in the Northeast Brazilian region was collected. Thus, calculated and measured flow rates were compared. The results proved that linearization error is negligible for practical purposes and the relative uncertainty increases as the flow rate decreases. The calculated values from both the Ramey and linear models were very close to the measured flow rates, presenting a difference of only 4.58 m³/d and 2.38 m³/d, respectively. Finally, the measurement uncertainties from the Ramey and linear models were equal to 1.22% and 1.40% (for injection zone 1); 10.47% and 9.88% (for injection zone 2). Therefore, the methodology was successfully validated and all objectives of this work were achieved.

  12. Flow Rates Measurement and Uncertainty Analysis in Multiple-Zone Water-Injection Wells from Fluid Temperature Profiles

    Directory of Open Access Journals (Sweden)

    José E. O. Reges

    2016-07-01

    Full Text Available This work is a contribution to the development of flow sensors in the oil and gas industry. It presents a methodology to measure the flow rates into multiple-zone water-injection wells from fluid temperature profiles and estimate the measurement uncertainty. First, a method to iteratively calculate the zonal flow rates using the Ramey (exponential model was described. Next, this model was linearized to perform an uncertainty analysis. Then, a computer program to calculate the injected flow rates from experimental temperature profiles was developed. In the experimental part, a fluid temperature profile from a dual-zone water-injection well located in the Northeast Brazilian region was collected. Thus, calculated and measured flow rates were compared. The results proved that linearization error is negligible for practical purposes and the relative uncertainty increases as the flow rate decreases. The calculated values from both the Ramey and linear models were very close to the measured flow rates, presenting a difference of only 4.58 m³/d and 2.38 m³/d, respectively. Finally, the measurement uncertainties from the Ramey and linear models were equal to 1.22% and 1.40% (for injection zone 1; 10.47% and 9.88% (for injection zone 2. Therefore, the methodology was successfully validated and all objectives of this work were achieved.

  13. An experimental setup for traceable measurement and calibration of liquid flow rates down to 5 nl/min.

    Science.gov (United States)

    Ahrens, Martin; Nestler, Bodo; Klein, Stephan; Lucas, Peter; Petter, Harm Tido; Damiani, Christian

    2015-08-01

    This work presents the improvements of an experimental setup for measuring ultra-low flow rates down to 5 nl/min. The system uses a telecentric CCD imaging system mounted on a high-precision, computer-controlled linear stage to track a moving liquid meniscus inside a glass capillary. Compared to the original setup, the lowest attainable expanded uncertainty at any flow rate has been reduced from 5.4% to 2%. In addition, the conformity with specification of three commercial micro-fluidic devices was evaluated using the new setup: one syringe pump, one implantable infusion pump and one thermal flow sensor. The flow sensor and the implantable infusion pump met the compliance criteria (coverage probability 95%). The syringe pump however, failed to meet the specifications at 5 nl/min and 10 nl/min. No assessment could be made at higher flow rates.

  14. Effects of Cooling Fluid Flow Rate on the Critical Heat Flux and Flow Stability in the Plate Fuel Type 2 MW TRIGA Reactor

    Directory of Open Access Journals (Sweden)

    H. P. Rahardjo

    2017-12-01

    Full Text Available The conversion program of the 2 MW TRIGA reactor in Bandung consisted of the replacement of cylindrical fuel (produced by General Atomic with plate fuel (produced by BATAN. The replacement led into the change of core cooling process from upward natural convection type to downward forced convection type, and resulted in different thermohydraulic safety criteria, such as critical heat flux (CHF limit, boiling limit, and cooling fluid flow stability. In this paper, a thermohydraulic safety analysis of the converted TRIGA reactor is presented by considering the Dynamic Nucleate Boiling Ratio (DNBR criterion, Onset Nucleate Boiling Ratio (ONBR limit, and cooling fluid flow stability at various cooling fluid flow rate.The numerical analyses were performed using the HEATHYD program on the hottest channels of reactor core.The combination of heat transfer and fluid flow analysis were conducted for reactor operation at 2 MW with 20 fuel element bundles and four control rod bundles. Incoming fluid flow to the cooling channel was fixed at 44.5 °C temperature and 1.9970 bar pressure, and its flow rate was varied from 1.25 to 3.5 m3/h. By inputting these values, as well as the total power of fuel elements per bundle, the wall temperature distribution of the plate fuel element, cooling fluid temperature distribution, and pressure losses in the channels were obtained for the analysis of CHF limit, boiling limit, and flow stability. It was shown that no boiling occurred for the cooling fluid flow rate range of 2.4 to 3.5 m3/h, and even at the cooling fluid flow rate of 1.25 m3/h where some bubbles occurred, the DNBR was higher than the critical limit (more than 23 while the flow stability criterion in some channels were slightly less than 1 (unstable. At the cooling fluid flow rate of 1.4 m3/h, however, the flow became stable in all channel. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance

    Science.gov (United States)

    Berteau, Cecile; Filipe-Santos, Orchidée; Wang, Tao; Rojas, Humberto E; Granger, Corinne; Schwarzenbach, Florence

    2015-01-01

    Aim The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC) injection pain tolerance. Methods The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP) combined with two different injection flow rates (0.02 and 0.3 mL/s). All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS) (0 mm/no pain, 100 mm/extreme pain). The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results Viscosity levels had significant impact on perceived injection pain (P=0.0003). Specifically, less pain was associated with high viscosity (VAS =12.6 mm) than medium (VAS =16.6 mm) or low (VAS =22.1 mm) viscosities, with a significant difference between high and low viscosities (P=0.0002). Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89). Slow (0.02 mL/s) or fast (0.30 mL/s) injection rates also showed no significant impact on perceived pain during SC injection (P=0.79). In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High viscosity injections were shown to be the most tolerated, whereas injection volume and flow rates did not impact perceived pain. PMID:26635489

  15. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance

    Directory of Open Access Journals (Sweden)

    Berteau C

    2015-11-01

    Full Text Available Cecile Berteau,1 Orchidée Filipe-Santos,1 Tao Wang,2 Humberto E Rojas,2 Corinne Granger,1 Florence Schwarzenbach1 1Becton-Dickinson Medical Pharmaceutical Systems, Le Pont de Claix, France; 2Eli Lilly and Company, Indianapolis, IN, USA Aim: The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC injection pain tolerance. Methods: The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP combined with two different injection flow rates (0.02 and 0.3 mL/s. All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS (0 mm/no pain, 100 mm/extreme pain. The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results: Viscosity levels had significant impact on perceived injection pain (P=0.0003. Specifically, less pain was associated with high viscosity (VAS =12.6 mm than medium (VAS =16.6 mm or low (VAS =22.1 mm viscosities, with a significant difference between high and low viscosities (P=0.0002. Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89. Slow (0.02 mL/s or fast (0.30 mL/s injection rates also showed no significant impact on perceived pain during SC injection (P=0.79. In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion: The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High

  16. Higher sweating rate and skin blood flow during the luteal phase of the menstrual cycle.

    Science.gov (United States)

    Lee, Haneul; Petrofsky, Jerrold; Shah, Nirali; Awali, Abdulaziz; Shah, Karan; Alotaibi, Mohammed; Yim, JongEun

    2014-10-01

    Evaporation by sweating is the most effective way to remove heat from the body. Sweat rates increase under both local and whole-body heat stress. Men and women differ in how they respond to heat, because sexual steroids alter resting body core temperature and the threshold for sweating and skin blood flow (SBF) during heating. The purpose of the present study was to compare local sweat rates and cutaneous vasodilatation during heat exposure in women with a regular menstrual cycle. The cutaneous vasodilatation was judged by measuring the SBF. Eight female and nine male subjects participated in this study, and their age range was 24-29 years. Female subjects were tested twice throughout one full menstrual cycle: once during the middle follicular phases and once during the luteal phase. Subjects remained in a temperature-regulated room at 41°C and 21% of relative humidity for 40 minutes. Sweat rate was recorded from the forehead, forearm, and thigh, and skin temperature and SBF were measured on the thigh and forehead. We found that the sweating rate and SBF were greater in the luteal phase compared to follicular phase (p0.05). We propose the enhanced sympathetic activity in the luteal phase with a regular menstrual cycle.

  17. Association beween resting heart rate, shear and flow-mediated dilation in healthy adults.

    Science.gov (United States)

    Fox, Brandon M; Brantley, Lucy; White, Claire; Seigler, Nichole; Harris, Ryan A

    2014-10-01

    Preclinical data have demonstrated that heart rate (HR) can directly impact vascular endothelial function, in part, through a shear-stress mechanism. This study sought to explore, in humans, the associations between resting heart rate and both shear and endothelial function assessed by flow-mediated dilation (FMD). The brachial artery FMD test was performed in 31 apparently healthy volunteers. Basal (B) and hyperaemic (H) shear were quantified in the following two ways using data from the FMD test: the traditional cumulative shear area under the curve up to peak dilation (Shearcum) method; and our novel method of shear summation (Shearsum), which accounts for HR by summing each individual cardiac cycle shear up to peak dilation. Data were grouped by tertiles based on resting HR as follows: low (LHR = 43-56 beats min(-1); n = 10); middle (MHR = 58-68 beats min(-1); n = 11); and high (HHR = 69-77 beats min(-1); n = 10). Within the LHR group, both B-Shearcum and H-Shearcum were significantly higher (P heart rate and both shear and endothelial function in humans. Moreover, these findings have implications for considering heart rate as an important physiological variable when quantifying shear and performing the FMD test. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

  18. Effects of air flow rate on the oxidation of NBG-18 and NBG-25 nuclear graphite

    Science.gov (United States)

    Chi, Se-Hwan; Chan Kim, Gen

    2017-08-01

    The effects of air flow rate (FR) (FR range: 1-10 L/min) on the oxidation of NBG-18 and NBG-25 nuclear graphite grades at temperatures between 600 and 1100 °C were studied, in reference to the standard test procedure for measuring oxidation rates of nuclear graphite in air (ASTM D 7542-09). The results showed that the FR effects on oxidation rate (OR) increase with increasing temperature with negligible FR effects at 600 °C for both materials. At high temperatures (>800 °C) there appears to be a two-stage relationship between FR and OR, which corresponds to the transition between reaction rates dominated by chemical kinetics and those dominated by diffusion. The material-specific microstructure appeared strongly influences this transition. The overall OR-FR behaviours of NBG-18 were higher than NBG-25 at 600-800 °C while negligible differences in the OR-FR behaviours between the two grades were observed at 900-1100 °C. The mercury porosimetry data showed that the higher OR-FR behaviours observed in NBG-18 may partly be attributed to the differences in the pore size distribution (open porosity and cumulative pore area) between the grades, especially for the large size pores (diameter ≫ 5 × 103 nm).

  19. Pink Wastewater Treatment Costs for a Granular Carbon System Operating at Flow Rates at or Below Design Capacity.

    Science.gov (United States)

    1983-08-01

    capacity after reduced flow values of the wastewaters are collected and stored versus the daily operation of the plant regardless of the influent flow ... rates . Examined and qualified in Present-VAlue dollars was the effect of dedicated versus part-time labor for operation of the carbon plant. The

  1. Changes in plasma volume, in transcapillary escape rate of albumin and in subcutaneous blood flow during hypoglycaemia in man

    DEFF Research Database (Denmark)

    Hilsted, J; Bonde-Petersen, F; Madsbad, S

    1985-01-01

    and transcapillary escape rate increased significantly during hypoglycaemia. Skin temperature and local subcutaneous adipose tissue blood flow were measured in four different regions. Both tended to decrease during hypoglycaemia and decreased significantly 2 h after hypoglycaemia. There was no correlation between...... changes in the two measurements, suggesting that there is no simple relationship between subcutaneous blood flow and skin temperature during hypoglycaemia....

  2. Higher Fresh Gas Flow Rates Decrease Tidal Volume During Pressure Control Ventilation.

    Science.gov (United States)

    Mohammad, Shazia; Gravenstein, Nikolaus; Gonsalves, Drew; Vasilopoulos, Terrie; Lampotang, Samsun

    2017-05-01

    We observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV. To model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare). For the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva. FGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow

  3. Effects of environmental tobacco smoke on peak expiratory flow rates on healthy school children

    Directory of Open Access Journals (Sweden)

    Vujnović-Živković Zorica

    2016-01-01

    Full Text Available Introduction: Tobacco smoke is one of the most important environmental pollutants (ETS. Passive exposure to tobacco smoke is involuntary and it presents a health risk for children. Objective: To establish if there are differences in Peak Expiratory Flow Rates (PEF values of healthy school children who live in households with and without tobacco smoke. Methods: PEF measurements were taken for 830 school children, from elementary schools in Nis and Laplje Selo. Measurements were obtained with new peak flow meters Vitalograf-normal range (EN 13826, 3 to 5 times. The highest values were taken for analysis. P < 0.05 was considered significant. Results: We considered PEF values for 830 healthy school children, 599 (72.17% from households with tobacco smoke (ETS, and 231 (27.83% without ETS. Exposure to parenteral smoking was associated with reduced PEF rates: 312.01 L/min (95% CI=301.38-322.65 L/min, for boys and 284.64 L/min (95% CI=275.73-293.55 L/min, for girls. PEF rates for children from households without ETS are 313.79 L/min (95% CI=295.63-331.93 L/min for boys, and 302.0 L/min (95% CI=287.02- 316.98 L/min for girls. PEF rates were significantly lower for girls from households with ETS (p<0.05. Boys, with and without ETS, had no statistically significant differences between their height, weight and age, so their PEF rates could be compared by their absolute values. For girls, this was not the case, and after age, height and weight adjustments their PEF rates showed no statistical significance (p= 0,346. Conclusions: Parental and household smoking were associated with decreased lung function in school age children. Although it's possible to reduce exposure to tobacco smoke in public places, it's important to inform parents about long-term impact of tobacco smoke on the health of their children.

  4. The dispersion behaviour of dry powder inhalation formulations cannot be assessed at a single inhalation flow rate.

    Science.gov (United States)

    Grasmeijer, Floris; de Boer, Anne H

    2014-04-25

    The dispersion performances of inhalation powders are often tested at only one inhalation flow rate in mechanistic formulation studies. This limited approach is challenged by studies showing that interactions exist between inhalation flow rate and the effects on dispersion performance of several formulation variables. In this note we explain that such interactions with inhalation flow rate are, in fact, always to be expected. Because these interactions may greatly affect conclusions concerning the effects of formulation variables and their underlying mechanisms, the utility of future dry powder inhalation formulation studies may benefit from an approach in which dispersion performance is by default tested over a range of inhalation flow rates. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Determination of Flow Rates in Capillary Liquid Chromatography Coupled to a Nanoelectrospray Source using Droplet Image Analysis Software.

    Science.gov (United States)

    Cohen, Alejandro M; Soto, Axel J; Fawcett, James P

    2016-08-02

    Liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS) is widely used in proteomic and metabolomic workflows. Considerable analytical improvements have been observed when the components of LC systems are scaled down. Currently, nano-ESI is typically done at capillary LC flow rates ranging from 200 to 300 nL/min. At these flow rates, trouble shooting and leak detection of LC systems has become increasingly challenging. In this paper we present a novel proof-of-concept approach to measure flow rates at the tip of electrospray emitters when the ionization voltage is turned off. This was achieved by estimating the changes in the droplet volume over time using digital image analysis. The results are comparable with the traditional methods of measuring flow rates, with the potential advantages of being fully automatable and nondisruptive.

  6. Thermodynamic Characteristic Study of a High-temperature Flow-rate Control Valve for Fuel Supply of Scramjet Engines

    National Research Council Canada - National Science Library

    ZENG Wen TONG Zhizhong LI Songjing LI Hongzhou ZHANG Liang

    2012-01-01

    ... and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet...

  7. Impact of Pulsatility and Flow Rates on Hemodynamic Energy Transmission in an Adult Extracorporeal Life Support System.

    Science.gov (United States)

    Wolfe, Rachel; Strother, Ashton; Wang, Shigang; Kunselman, Allen R; Ündar, Akif

    2015-07-01

    This study investigated the total hemodynamic energy (THE) and surplus hemodynamic energy transmission (SHE) of a novel adult extracorporeal life support (ECLS) system with nonpulsatile and pulsatile settings and varying pulsatility to define the most effective setting for this circuit. The circuit consisted of an i-cor diagonal pump (Xenios AG, Heilbronn, Germany), an XLung membrane oxygenator (Xenios AG), an 18 Fr Medos femoral arterial cannula (Xenios AG), a 23/25 Fr Estech RAP femoral venous cannula (San Ramon, CA, USA), 3/8 in ID × 140 cm arterial tubing, and 3/8 in ID × 160 cm venous tubing. Priming was done with lactated Ringer's solution and packed red blood cells (HCT 36%). The trials were conducted at flow rates 1-4 L/min (1 L/min increments) under nonpulsatile and pulsatile mode, with differential speed values 1000-4000 rpm (1000 rpm increments) at 36°. The pseudo patient's mean arterial pressure was kept at 100 mm Hg using a Hoffman clamp during all trials. Real-time flow and pressure data were collected using a custom-based data acquisition system. Mean pressures across the circuit increased with increasing flow rates, but increased insignificantly with increasing differential speed values. Mean pressure did not change significantly between pulsatile and nonpulsatile modes. Pulsatile flow created more THE than nonpulsatile flow at the preoxygenator site (P flow rates. No SHE was created with nonpulsatile flow, but SHE was created with pulsatile flow, and increased with increasing differential speed values. At lower flow rates (1-2 L/min), the arterial cannula contributed the most to SHE loss, but at higher flow rates the arterial tubing created the most SHE loss. The circuit pressure drop values across all flow rates were 33.1-246.5 mm Hg, and were slightly higher under pulsatile mode than nonpulsatile mode. The i-cor diagonal pump creates satisfactory pulsatile and nonpulsatile flows, and can easily change the

  8. Effect of Change in Portal Vein Flow Rates on Hepatic Ablations Created with a Bipolar Radiofrequency Ablation Device.

    Science.gov (United States)

    Dodd, Gerald D; Lanctot, Anthony C; Lind, Kimberly E

    2017-05-01

    Purpose To investigate the effect of change in portal vein flow rates on the size and shape of ablations created by a bipolar radiofrequency (RF) ablation device. Materials and Methods This study was exempt from institutional animal care and use committee review. An in vitro bovine liver model perfused with autologous blood via the portal vein at three flow rates (60, 80, 100 mL/min per 100 g of liver) was used. Four ablations, two bipolar and two monopolar (control probe), were made in each of five livers perfused at each flow rate. Short- and long-axis diameters were measured from gross specimens, and volume and sphericity index were calculated for each ablation. A general linear mixed model accounting for correlation within the liver was used to evaluate the effects of flow on ablations. Analyses were performed by using software. Results There was no significant difference in the size or shape of ablations created by the bipolar device at the different flow rates (P > .05 for all outcomes). The monopolar device demonstrated the expected inverse association between ablation size and change in flow (P flow rates does not have a statistically significant effect on the size or shape of ablations created by the bipolar RF ablation device tested. (©) RSNA, 2016.

  9. Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

    Science.gov (United States)

    Muthiah, Kavitha; Gupta, Sunil; Otton, James; Robson, Desiree; Walker, Robyn; Tay, Andre; Macdonald, Peter; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, Kumud; Spratt, Phillip; Jansz, Paul; Hayward, Christopher S

    2014-08-01

    The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  10. Nanoimprinted distributed feedback dye laser sensors for high frame rate refractometric imaging of dissolution and fluid flow

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten

    2015-01-01

    High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA.......High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA....

  11. Analysis of Causes of Non-Uniform Flow Distribution in Manifold Systems with Variable Flow Rate along Length

    Science.gov (United States)

    Zemlyanaya, N. V.; Gulyakin, A. V.

    2017-11-01

    The uniformity of flow distribution in perforated manifolds is a relevant task. The efficiency of water supply, sewerage and perflation systems is determined by hydraulics of the flow with a variable mass. The extensive study of versatile available information showed that achieving a uniform flow distribution through all of the outlets is almost impossible. The analysis of the studies conducted by other authors and our numerical experiments performed with the help of the software package ANSYS 16.1 were made in this work. The results allowed us to formulate the main causes of non-uniform flow distribution. We decided to suggest a hypothesis to explain the static pressure rise problem at the end of a perforated manifold.

  12. Scaling of normalized mean energy and scalar dissipation rates in a turbulent channel flow

    Science.gov (United States)

    Abe, Hiroyuki; Antonia, Robert Anthony

    2011-05-01

    Non-dimensional parameters for the mean energy and scalar dissipation rates Cɛ and Cɛθ are examined using direct numerical simulation (DNS) data obtained in a fully developed turbulent channel flow with a passive scalar (Pr = 0.71) at several values of the Kármán (Reynolds) number h+. It is shown that Cɛ and Cɛθ are approximately equal in the near-equilibrium region (viz., y+ = 100 to y/h = 0.7) where the production and dissipation rates of either the turbulent kinetic energy or scalar variance are approximately equal and the magnitudes of the diffusion terms are negligibly small. The magnitudes of Cɛ and Cɛθ are about 2 and 1 in the logarithmic and outer regions, respectively, when h+ is sufficiently large. The former value is about the same for the channel, pipe, and turbulent boundary layer, reflecting the similarity between the mean velocity and temperature distributions among these three canonical flows. The latter value is, on the other hand, about twice as large as in homogeneous isotropic turbulence due to the existence of the large-scale u structures in the channel. The behaviour of Cɛ and Cɛθ impacts on turbulence modeling. In particular, the similarity between Cɛ and Cɛθ leads to a simple relation for the scalar variance to turbulent kinetic energy time-scale ratio, an important ingredient in the eddy diffusivity model. This similarity also yields a relation between the Taylor and Corrsin microscales and analogous relations, in terms of h+, for the Taylor microscale Reynolds number and Corrsin microscale Peclet number. This dependence is reasonably well supported by both the DNS data at small to moderate h+ and the experimental data of Comte-Bellot [Ph. D. thesis (University of Grenoble, 1963)] at larger h+. It does not however apply to a turbulent boundary layer where the mean energy dissipation rate, normalized on either wall or outer variables, is about 30% larger than for the channel flow.

  13. Steam distillation extraction of ginger essential oil: Study of the effect of steam flow rate and time process

    Science.gov (United States)

    Fitriady, Muhammad Arifuddin; Sulaswatty, Anny; Agustian, Egi; Salahuddin, Aditama, Deska Prayoga Fauzi

    2017-01-01

    In Indonesia ginger was usually used as a seasoning for dishes, an ingredient for beverage and a source of herbal medicines. Beside raw usage, ginger can be processed to obtain the essential oil which has many advantages such as proven to be an active antimicrobial and having an antioxidant ability. There are a lot of methods to extract essential oil from ginger, one of which is steam distillation. The aim of the current study was to investigate the effect of variation of time process and steam flow rate in the yield on ginger essential oil steam distillation extraction process. It was found that the best operation condition was 0.35 ml/s as the steam flow rate which yields 2.43% oil. The optimum time process was predicted at 7.5 hours. The composition of the oil was varied depend on the flow rate and every flow rate has its own major component contained in the oil. Curcumene composition in the oil was increased as increased steam flow rate applied, but the composition of camphene was decreased along with the increasing steam flow rate.

  14. Experimental comparison of performances of Mega Acer Kit, Ranger and ThermoSens according to flow rates and distances.

    Science.gov (United States)

    Seo, Hong Ju; Kim, Sang Hun; An, Tae Hun; Kim, Dong Joon

    2017-02-07

    We experimentally investigated the fluid warming performances of three warmers with different technology, according to flow rates and distances. We used the following intravenous fluid warmers: Mega Acer Kit (Group M, n = 8), Ranger (group R, n = 8), and ThermoSens (group T, n = 8). Fluids that had been stored in the operating room over the previous 24 h were delivered at sequent flow rates of from 440 mL/h up to 2500 mL/h through preheated warming devices. The fluid temperatures were recorded at the inlet point, 76-cm proximal (Pout1) and 166-cm distal outlet points (Pout2) every 1 min for 10 min. We repeated each test eight times. The delivered fluid temperature [mean (95% confidence interval)] was significantly higher in group M than group R and T at flow rates up to 650 mL/h with the highest value at 440 mL/h [34.30 (33.35-35.24)°C] (P flow rates over 1140 mL/h at Pout1 [36.67 (36.62-36.73)°C and 37.85 (37.52-38.17)°C at 2500 mL/h, respectively] (P flow rates for each device (P flow rates. Furthermore, the device performance is more effective with shorter extension lines.

  15. Very-high-flow injection rate for upper abdominal CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Masashi; Minamiguti, Hiroki; Hagihira, Takami; Kishi, Kazushi; Sato, Morio [Wakayama Medical Coll. (Japan); Shioyama, Yasukazu; Okumura, Toshiyuki; Yamada, Kouji; Kawashima, Michihisa [Central Hospital and Cancer Center of Ibaraki Prefecture, Tomobe (Japan)

    2002-06-01

    The purpose of this study was to compare a very-high-flow injection-rate method (group A) and a conventional injection-rate method (group B) for visualization of upper abdominal arteries by multidetector helical computed tomography (MDHCT). The subjects were 240 patients suspected to have abdominal lesions. They were randomly assigned to group A (120 patients) and group B (120 patients). In group A, the bilateral medial cubital veins were punctured, and contrast medium was infused at a rate of 8.6-9.6 ml/s. In group B, the unilateral medial cubital vein was punctured, and contrast medium was infused at a rate of 2.0-3.0 ml/s. The quality of vascular visualization was graded as poor, good, or excellent by three radiologists. All visualizations of the celiac trunk (CE) and superior mesenteric artery (SMA) were graded as excellent in both group A and group B. Visualization grades of the subsegmental branches of the hepatic artery (HA), right gastric artery (RGA), cystic artery, dorsal pancreatic artery (DPA), and superior pancreaticoduodenal artery (SPDA) were good or excellent in 75% (paging method)/53.3% (three-dimensional method), 85%/30%, 77.7%/18.3%, 76.7%/28.3%, and 88.3%/42.5%, respectively, in group A, and 33.3%/11.7%, 46.7%/3.4%, 41.6%/5%, 55%/4.2%, and 72.5%/14.2%, respectively, in group B. The appearance rate of intrahepatic portal branches was 28.3% in group A and 66.7% in group B in the arterial dominant phase. Group A showed better visualization results than Group B in upper abdominal arteries according to MDHCT. (author)

  16. Regulation of urinary thromboxane B2 in man: influence of urinary flow rate and tubular transport

    Energy Technology Data Exchange (ETDEWEB)

    Zipser, R.D.; Smorlesi, C.

    1984-02-01

    Thromboxane B2 (TxB) is excreted in human urine, but the mechanism of renal excretion and the quantitative relationship of urinary TxB to the active parent compound, thromboxane A2, of renal or extrarenal origin is not established. To determine the effects of vasoactive hormones, uricosuric agents and urinary flow rate on TxB excretion, urinary TxB was measured by radioimmunoassay and mass spectrometry, and renal metabolism of blood TxB was determined by radiochromatography of urine after i.v. (3H)-TxB infusions. Basal TxB was 6.7 +/- 1.1 ng/h during an oral water load, and TxB fell with s.g. antidiuretic hormone (to 3.4 +/- 0.4 ng/h, P less than 0.01) and with fluid restriction (to 2.6 +/- 0.5 ng/hr, P . 0.001) in parallel with urinary volume. Urinary excretion of unmetabolized (3H)-TxB also fell (by 56%) with fluid restriction, implicating altered metabolism rather than synthesis as the mechanism of the urinary flow effect. Angiotensin II infusions slightly reduced both TxB and urine volume, consistent with a flow effect. In contrast, probenecid did not alter urine volume, but increased urinary uric acid (by 244%), TxB (from 5.6 +/- 0.9 to 11.1 +/- 2.9 ng/h) and urinary excretion of blood (3H)-TxB (by 243%) by similar amounts (all P less than 0.05), suggesting that TxB is actively reabsorbed in the proximal tubule, similarly to uric acid. Thus, urinary excretion of TxB of renal and extrarenal origin is regulated by proximal and distal tubule factors.

  17. Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

    Science.gov (United States)

    Fiscaletti, D.; Elsinga, G. E.; Attili, A.; Bisetti, F.; Buxton, O. R. H.

    2016-10-01

    The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor ei, with the vorticity vector ω , is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors | ei.ω ̂| are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e1, in contrast to the global tendency for ω to be aligned in parallel with the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008), 10.1063/1.3021055]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between ω and nonlocal e1 and that the strongly swirling worms are kinematically significant to this process.

  18. Phosphorus mobilization in rewetted peat and sand at variable flow rate and redox regimes

    DEFF Research Database (Denmark)

    Kjærgaard, Charlotte; Heiberg, Lisa; Jensen, Henning S.

    2012-01-01

    rates from 7.6 to 11 mg P m−2 day−1. Organic or particulate P contributed to 40–45% of total P losses from the peat. In contrast, the high O2 supply during high flow rate kept the peat oxic and lowered TP release rates to 6.7 mg P m−2 day−1. The carbon poor sand demonstrated that this soil type......Despite the high priority of wetland restoration as the primary measure to reduce agricultural nutrient loads, it is also widely recognized that wetlands restored on former agricultural land could potentially release accumulated phosphorus (P) and become a source of eutrophication. Simulating...... regimes in the two soils during 21 or 67 days of continuous percolation at either 1 or 4 mm h−1. Anoxic conditions occurred in the peat soil at both low oxygen supply and anoxic infiltration, causing reductive Fe(III) dissolution with high Fe(II) and P effluent concentrations and total P (TP) release...

  19. The influence of surface sorption and air flow rate on phthalate emissions from vinyl flooring: Measurement and modeling

    Science.gov (United States)

    Liang, Yirui; Xu, Ying

    2015-02-01

    This study investigated the influences of surface sorption and air flow rate on the emission of phthalates from building materials. Controlled tests were conducted in specially designed stainless steel and wood chambers, and the steady-state concentration in the stainless steel chamber was about 2-3 times higher than that in the wood chamber for di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP). The emission rate of phthalates increased in the wood chamber due to the diffusion mass flow through the chamber wall (i.e., surface absorption). The adsorption isotherm of phthalates on the stainless steel surface and the absorption parameters (i.e., diffusion and partition coefficients) of phthalates on the wood surface were determined experimentally, and the values were comparable to those in the literature. The equilibration time scale for phthalates absorbed to the sink reservoir in actual indoor environments was estimated and can be substantial (approximately 80 years), indicating that surface absorption may continuously drive phthalates from their indoor sources to various sinks and thus significantly increase the emission rate of phthalates. The gas-phase concentration of DEHP was measured in two stainless steel chambers operated at flow rates of 300 mL/min and 3000 mL/min, respectively, which were both adjusted to 1000 mL/min after steady state was reached. The gas-phase concentration of DEHP in the chamber was very sensitive to the chamber air flow rate, and higher air flow rates resulted in lower concentration levels. However, the increased emission rate compensated for the dilution in the gas phase and made the DEHP concentration not drop substantially with an increase in the air flow rate. Independently measured or calculated parameters were used to validate a semi-volatile organic compounds (SVOCs) emission model that included absorptive surfaces and for a range of air flow rates, with excellent agreement between the model predictions and the

  20. A relationship between salivary flow rates and Candida counts in patients with xerostomia.

    Science.gov (United States)

    Nadig, Suchetha Devendrappa; Ashwathappa, Deepak Timmasandra; Manjunath, Muniraju; Krishna, Sowmya; Annaji, Araleri Gopalkrishna; Shivaprakash, Praveen Kunigal

    2017-01-01

    Most of the adult population is colonized by Candida in their oral cavity. The process of colonization depends on several factors, including the interaction between Candida and salivary proteins. Therefore, salivary gland hypofunction may alter the oral microbiota and increase the risk for opportunistic infections, such as candidiasis. Hence, it is necessary to evaluate the relationship between salivary flow rates (SFRs) and Candida colony counts in the saliva of patients with xerostomia. This study aims to determine and evaluate the relationship between SFRs and Candida colony forming units (CFUs) in patients with xerostomia. This study was a descriptive study. The study participants were taken from the patients attending outpatient department in a private dental college. Fifty patients, who reported xerostomia in a questionnaire of the symptoms of xerostomia, were selected. Chewing stimulated whole saliva samples were collected from them and their SFRs were assessed. Saliva samples were inoculated in the Sabouraud dextrose agar culture media for 24-48 h, and Candida CFUs were counted. Chi-squared test was used to analyze the data. There was a significant inverse relationship between salivary flow and candida CFUs count when patients with high colony counts were analyzed (cutoff point of 400 or greater CFU/mL). Females had less SFR than males. Most of the patients who had hyposalivation were taking medication for the underlying systemic diseases. Candida albicans was the most frequent species. There was a significantly negative correlation between SFRs and Candida CFUs in the patients with xerostomia.

  1. Do eosinophil counts correlate differently with asthma severity by symptoms versus peak flow rate?

    Science.gov (United States)

    Koshak, E A; Alamoudi, O S

    1999-12-01

    Discrepancy in asthmatic assessment by symptoms and peak flow rate (PFR) is a frequent dilemma. Currently, total peripheral eosinophil count (TPEC) is under study for asthma evaluation. To explore the correlation between TPEC and asthma severity assessed by symptoms alone versus symptoms and PFR. Adults asthmatics were selected from the Asthma Clinic. Severity assessment was based on two methods: symptoms alone or symptoms and PFR. Expiratory PFR was recorded by a Wright peak flow meter. Severity levels included mild intermittent, mild persistent, moderate persistent, and severe persistent. Total peripheral eosinophil count was performed on a Celldyn-3500 counter. Data was analyzed for statistical significance. Sixty asthmatics aged 15 to 70 years (mean = 34 years), of which 68.3% were female, were studied. Severity levels differed between the two assessment methods in 45% of the cases and showed a predominance of the moderate persistent type. Total peripheral eosinophil count ranged between 22 and 2470 cells/mm3 (mean = 520 +/- SD = 393) and eosinophilia was found in 50% of the cases. Total peripheral eosinophil count showed a high positive correlation with increased asthma severity level assessed by history alone (r = 0.460, P < .001); more than by history and PFR (r = 0.328, P < .05). The discrepancy between symptoms and PFR is confirmed by these results. A reliable objective parameter in asthma assessment is a continuous challenge. This study advocates the possible supplementation of TPEC as another objective parameter that might help in selecting the appropriate severity level in asthmatics.

  2. Enabling high-rate electrochemical flow capacitors based on mesoporous carbon microspheres suspension electrodes

    Science.gov (United States)

    Tian, Meng; Sun, Yueqing; Zhang, Chuanfang (John); Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2017-10-01

    Electrochemical flow capacitor (EFC) is a promising technology for grid energy storage, which combines the fast charging/discharging capability of supercapacitors with the scalable energy capacity of flow batteries. In this study, we report a high-power-density EFC using mesoporous carbon microspheres (MCMs) as suspension electrodes. By using a simple yet effective spray-drying technique, monodispersed MCMs with average particle size of 5 μm, high BET surface area of 1150-1267 m2 g-1, large pore volume of 2-4 cm3 g-1 and controllable mesopore size of 7-30 nm have been successfully prepared. The resultant MCMs suspension electrode shows excellent stability and considerable high capacitance of 100 F g-1 and good cycling ability (86% of initial capacitance after 10000 cycles). Specially, the suspension electrode exhibits excellent rate performance with 75% capacitance retention from 2 to 100 mV s-1, significantly higher than that of microporous carbon electrodes (20∼30%), due to the developed mesoporous channels facilitating for rapid ion diffusion. In addition, the electrochemical responses on both negative and positive suspension electrodes are studied, based on which an optimal capacitance matching between them is suggested for large-scale EFC unit.

  3. Exposure Time Distributions reveal Denitrification Rates along Groundwater Flow Path of an Agricultural Unconfined Aquifer

    Science.gov (United States)

    Kolbe, T.; Abbott, B. W.; Thomas, Z.; Labasque, T.; Aquilina, L.; Laverman, A.; Babey, T.; Marçais, J.; Fleckenstein, J. H.; Peiffer, S.; De Dreuzy, J. R.; Pinay, G.

    2016-12-01

    Groundwater contamination by nitrate is nearly ubiquitous in agricultural regions. Nitrate is highly mobile in groundwater and though it can be denitrified in the aquifer (reduced to inert N2 gas), this process requires the simultaneous occurrence of anoxia, an electron donor (e.g. organic carbon, pyrite), nitrate, and microorganisms capable of denitrification. In addition to this the ratio of the time groundwater spent in a denitrifying environment (exposure time) to the characteristic denitrification reaction time plays an important role, because denitrification can only occur if the exposure time is longer than the characteristic reaction time. Despite a long history of field studies and numerical models, it remains exceedingly difficult to measure or model exposure times in the subsurface at the catchment scale. To approach this problem, we developed a unified modelling approach combining measured environmental proxies with an exposure time based reactive transport model. We measured groundwater age, nitrogen and sulfur isotopes, and water chemistry from agricultural wells in an unconfined aquifer in Brittany, France, to quantify changes in nitrate concentration due to dilution and denitrification. Field data showed large differences in nitrate concentrations among wells, associated with differences in the exposure time distributions. By constraining a catchment-scale characteristic reaction time for denitrification with water chemistry proxies and exposure times, we were able to assess rates of denitrification along groundwater flow paths. This unified modeling approach is transferable to other catchments and could be further used to investigate how catchment structure and flow dynamics interact with biogeochemical processes such as denitrification.

  4. Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, W.J. III.

    1988-10-12

    A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; pressure wave reflector means in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector means and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value. 8 figs.

  5. Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, III, William J. (Kent, WA)

    1990-01-01

    A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

  6. The Role of Inspiratory Pressures in Determining the Flow Rates Though Dry Powder Inhalers; A Review.

    Science.gov (United States)

    Clark, Andrew R

    2015-01-01

    Dry powder inhalers are one of the most popular devices for delivering medication directly to the lungs of patients. Both for local action and when using the lungs as a portal of entry into the systemic circulation. Dry powder inhalers rely on the patient's inspiratory effort to supply the energy for the device to effectively deliver medication. In this respect they are limited by the airway pressures that a patient can generate with their respiratory muscles. In this review we focus on a simple model outlining the variables influencing respiratory pressure and review the literature on inspiratory flow rates in patients with respiratory disease. The main determinants of the capability to generate the pressure necessary to effectively use a dry powder inhaler are shown to be age and gender, not disease or disease severity.

  7. Antibody-Functionalized Fluid-Permeable Surfaces for Rolling Cell Capture at High Flow Rates

    Science.gov (United States)

    Mittal, Sukant; Wong, Ian Y.; Deen, William M.; Toner, Mehmet

    2012-01-01

    Adhesion-based cell capture on surfaces in microfluidic devices forms the basis of numerous biomedical diagnostics and in vitro assays. However, the performance of these platforms is partly limited by interfacial phenomena that occur at low Reynolds numbers. In contrast, cell homing to porous vasculature is highly effective in vivo during inflammation, stem cell trafficking, and cancer metastasis. Here, we show that a porous, fluid-permeable surface functionalized with cell-specific antibodies promotes efficient and selective cell capture in vitro. This architecture is advantageous due to enhanced transport as streamlines are diverted toward the surface. Moreover, specific cell-surface interactions are promoted due to reduced shear, allowing gentle cell rolling and arrest. Together, these synergistic effects enable highly effective cell capture at flow rates more than an order of magnitude larger than those provided by existing devices with solid surfaces. PMID:22385842

  8. Effect on air quality and flow rate of fresh water production in humidification and dehumidification system

    Science.gov (United States)

    Rajasekar, K.; Pugazhenthi, R.; Selvaraju, A.; Manikandan, T.; Saravanan, R.

    2017-03-01

    Water is the vital need of any living organisms of the world when water fails, functions of nature cease the world. The water scarcity is one of the major problems to be faced by the developing world, which indicates a critical need to develop inexpensive small-scale desalination technologies. The cost of the desalination process takes more, so the world expecting the desalination plants with minimum operating cost, so the utilization of renewable energy source is a preferable one. This research article provides a glimpse of an overview of the humidification-dehumidification (HDH) based desalination method which uses the solar energy. The HDH based desalination method monitored and evaluated the performance parameters, i.e. mass flow rates of water and air.

  9. A Rate-Dependent Shear Transformation Zone Model of Shear Band Formation During Flow

    Science.gov (United States)

    Hinkle, Adam R.; Falk, Michael L.

    2015-03-01

    Recent shear-experiments of carbopol gels have revealed the formation of a transient shear band before reaching the steady-state characterized by homogeneous flow. Analysis of this phenomenon using a rate-dependent effective temperature in the shear transformation zone (STZ) theory reveals that the observed fluidization proceeds via two distinct processes: A shear band initiates and broadens via disordering at the interface of the band. This is accompanied by spatially homogeneous fluidization outside of the shear band where the disorder of the gel grows uniformly. Experimental data are used to parameterize the STZ theory, and direct, quantitative comparison is made to measurements of the structural evolution of the gel. NSF IGERT Fellowship Award No. 0801471.

  10. Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests.

    Directory of Open Access Journals (Sweden)

    Wei He

    Full Text Available A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF for space instruments. A model for the system functional error rate (SFER is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA is presented. Based on experimental results of different ions (O, Si, Cl, Ti under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10-3(error/particle/cm2, while the MTTF is approximately 110.7 h.

  11. Standard practice for measurement of the glass dissolution rate using the single-pass flow-through test method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice describes a single-pass flow-through (SPFT) test method that can be used to measure the dissolution rate of a homogeneous silicate glass, including nuclear waste glasses, in various test solutions at temperatures less than 100°C. Tests may be conducted under conditions in which the effects from dissolved species on the dissolution rate are minimized to measure the forward dissolution rate at specific values of temperature and pH, or to measure the dependence of the dissolution rate on the concentrations of various solute species. 1.2 Tests are conducted by pumping solutions in either a continuous or pulsed flow mode through a reaction cell that contains the test specimen. Tests must be conducted at several solution flow rates to evaluate the effect of the flow rate on the glass dissolution rate. 1.3 This practice excludes static test methods in which flow is simulated by manually removing solution from the reaction cell and replacing it with fresh solution. 1.4 Tests may be conducted wit...

  12. A database on post-fire erosion rates and debris flows in Mediterranean-Basin watersheds

    Science.gov (United States)

    Parise, M.; Cannon, S. H.

    2009-04-01

    proceedings. The database derives from critical analysis of the existing literature, integrated by case studies directly studied by the authors. Studies on recently burned areas in the Mediterranean basin are most frequently carried out on small experimental plots, often with simulated rainfall A problem of scale therefore exists when trying to extrapolate the erosion rates (also reported as sediment yields or as sediment losses) from these studies to a watershed scale. Very few articles, on the other hand, were found that document the watershed-scale response of basins to rainfall-induced erosion and debris flows following wildfires. The few reported cases of debris flows in the Mediterranean Basin describe erosion of sediment from the hillslopes and the channels (sometimes down to bedrock), and, for a limited number of sites, failure of discrete landslides. This information indicates that debris-flow generation from recently burned areas in the Mediterranean basin appears to occur primarily through sediment bulking processes. Nevertheless, the database so far compiled shows a distribution of post-fire erosion and debris flows in the western Mediterranean basin (Spain, essentially, but also Portugal), followed by the eastern Mediterranean area (Israel), and then by France, Italy and Greece. Even though still in a preliminary version, that needs to be integrated and updated from further sources, our data compilation allows for the unique opportunity to examine issues related to the generation of post-wildfire debris flows across a variety of environments and under a variety of conditions, and to move from a qualitative conception of the controls on post-fire debris-flow generation to the definition of specific conditions that result in their occurrence. Future activities of the project will include: i) updating and integration of the preliminary version of the database; ii) development of models that can be used to identify the probability of debris-flow occurrence and the

  13. Constraints on flow regimes in wide-aperture fractures

    Energy Technology Data Exchange (ETDEWEB)

    Ghezzehei, Teamrat A.

    2004-02-28

    In recent years, significant advances have been made in our understanding of the complex flow processes in individual fractures, aided by flow visualization experiments and conceptual modeling efforts. These advances have led to the recognition of several flow regimes in individual fractures subjected to different initial and boundary conditions. Of these, the most important regimes are film flow, rivulet flow, and sliding of droplets. The existence of such significantly dissimilar flow regimes has been a major hindrance in the development of self-consistent conceptual models of flow for single fractures that encompass all the flow regimes. The objective of this study is to delineate the existence of the different flow regimes in individual fractures. For steady-state flow conditions, we developed physical constraints on the different flow regimes that satisfy minimum energy configurations, which enabled us to segregate the wide range of fracture transmissivity (volumetric flow rate per fracture width) into several flow regimes. These are, in increasing order of flow rate, flow of adsorbed films, flow of sliding drops, rivulet flow, stable film flow, and unstable (turbulent) film flow. The scope of this study is limited to wide-aperture fractures with the flow on the opposing sides of fracture being independent.

  14. Rate of change of cerebral blood flow velocity with hyperventilation during anesthesia in humans.

    Science.gov (United States)

    Chong, K Y; Craen, R A; Murkin, J M; Lee, D; Eliasziw, M; Gelb, A W

    2000-02-01

    Although it has been suggested that the rate at which the cerebral circulation responds to changes in PaCO2 is different with differing anesthetics, there have been no attempts to measure this. Transcranial Doppler allows the continuous measurement of cerebral blood flow velocity (CBFV) and any changes over time. Our aim was to compare the rate of change of CBFV when end-tidal CO2 (P(ET)CO2) was rapidly altered during halothane or isoflurane anesthesia. Twenty-eight unpremedicated healthy patients were randomly assigned to receive air/O2 and either 1-1.5 MAC halothane or isoflurane as the primary anesthetic. After 15 min of steady state, P(ET)CO2 was rapidly reduced from 45 mm Hg to 30 mm Hg. CBFV and P(ET)CO2 were recorded every 30 sec for the next 10 min. The rate of change of normalized CBFV (delta CBFV vs. delta time) was more rapid in the isoflurane group (P <0.0001) especially in the initial few minutes. In all patients anesthetized with isoflurane, and in all but two patients anesthetized with halothane, the reduction in P(ET)CO2 produced a corresponding decrease in CBFV However, there were no differences in the magnitude of cerebrovascular CO2 reactivity (delta CBFV vs. delta P(ET)CO2) between the two groups. The rate of change of CBFV was faster in the isoflurane than in the halothane group especially in the initial few minutes. Indeed, for two patients in the halothane group Vmca did not change despite a change in P(ET)CO2. This may be of clinical importance when cerebrovascular tone needs to be changed rapidly.

  15. Visualization and computer graphics on isotropically emissive volumetric displays.

    Science.gov (United States)

    Mora, Benjamin; Maciejewski, Ross; Chen, Min; Ebert, David S

    2009-01-01

    The availability of commodity volumetric displays provides ordinary users with a new means of visualizing 3D data. Many of these displays are in the class of isotropically emissive light devices, which are designed to directly illuminate voxels in a 3D frame buffer, producing X-ray-like visualizations. While this technology can offer intuitive insight into a 3D object, the visualizations are perceptually different from what a computer graphics or visualization system would render on a 2D screen. This paper formalizes rendering on isotropically emissive displays and introduces a novel technique that emulates traditional rendering effects on isotropically emissive volumetric displays, delivering results that are much closer to what is traditionally rendered on regular 2D screens. Such a technique can significantly broaden the capability and usage of isotropically emissive volumetric displays. Our method takes a 3D dataset or object as the input, creates an intermediate light field, and outputs a special 3D volume dataset called a lumi-volume. This lumi-volume encodes approximated rendering effects in a form suitable for display with accumulative integrals along unobtrusive rays. When a lumi-volume is fed directly into an isotropically emissive volumetric display, it creates a 3D visualization with surface shading effects that are familiar to the users. The key to this technique is an algorithm for creating a 3D lumi-volume from a 4D light field. In this paper, we discuss a number of technical issues, including transparency effects due to the dimension reduction and sampling rates for light fields and lumi-volumes. We show the effectiveness and usability of this technique with a selection of experimental results captured from an isotropically emissive volumetric display, and we demonstrate its potential capability and scalability with computer-simulated high-resolution results.

  16. Comparison of cutting efficiency with different diamond burs and water flow rates in cutting lithium disilicate glass ceramic.

    Science.gov (United States)

    Siegel, Sharon C; Patel, Tejas

    2016-10-01

    This study compared different diamond burs and different water flow rates on the cutting efficiency of sectioning through lithium disilicate glass ceramic. The authors used a standardized cutting regimen with 4 brands of diamond burs to section through lithium disilicate glass ceramic blocks. Twelve diamonds of each brand cut through the blocks in randomized order. In the first part of the study, the authors recorded sectioning rates in millimeters per minute for each diamond bur as a measure of cutting efficiency. In the second part of the study, the authors compared sectioning rates using only 1 brand of diamond bur, with 3 different water flow rates. The authors averaged and compared cutting rates of each brand of diamond bur and the cutting rates for each flow rate using an analysis of variance and determined the differences with a Tukey honest significant difference test. One diamond bur cut significantly slower than the other 3, and one diamond bur cut significantly faster than 2 of the others. The diamond bur cutting efficiency through lithium disilicate glass ceramic with a 20 mL/min water flow rate was significantly higher than 15 mL/min. There are differences in cutting efficiency between diamond burs when sectioning lithium disilicate glass ceramic. Use a minimum of 20 mL/min of water coolant flow when sectioning lithium disilicate glass ceramic with dental diamond burs to maximize cutting efficiency. Recommendations for specific diamond burs with a coarse grit and water flow rate of 20 mL/min can be made when removing or adjusting restorations made from lithium disilicate glass ceramic. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

  17. ChargeOut! : determining machine and capital equipment charge-out rates using discounted cash-flow analysis

    Science.gov (United States)

    E.M. (Ted) Bilek

    2007-01-01

    The model ChargeOut! was developed to determine charge-out rates or rates of return for machines and capital equipment. This paper introduces a costing methodology and applies it to a piece of capital equipment. Although designed for the forest industry, the methodology is readily transferable to other sectors. Based on discounted cash-flow analysis, ChargeOut!...

  18. A comprehensive model to determine the effects of temperature and species fluctuations on reaction rates in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.

    1986-01-01

    A computationally-viable model describing the interaction between fluid-mechanical turbulence and finite-rate combustion reactions, principally in high-speed flows was developed. Chemical kinetic mechanisms, complete and global, were developed describing the finite rate reaction of fuels of interest to NASA. These fuels included principally hydrogen and silane, although a limited amount of work involved hydrocarbon fuels as well.

  19. A method of predicting flow rates required to achieve anti-icing performance with a porous leading edge ice protection system

    Science.gov (United States)

    Kohlman, D. L.; Albright, A. E.

    1983-01-01

    An analytical method was developed for predicting minimum flow rates required to provide anti-ice protection with a porous leading edge fluid ice protection system. The predicted flow rates compare with an average error of less than 10 percent to six experimentally determined flow rates from tests in the NASA Icing Research Tunnel on a general aviation wing section.

  20. Optimization of liquid and gas flow rates for aerated drilling fluids considering hole cleaning for vertical and low inclination wells

    Energy Technology Data Exchange (ETDEWEB)

    Ozbayoglu, M.E. [Middle East Univ., Metn (Lebanon)

    2009-07-01

    One of the most widely used technologies in depleted and/or low pressured formations is underbalanced drilling. Drilling fluids are usually gasified in order to achieve underbalanced conditions. The most commonly used drilling fluids during underbalanced drilling are pure gas, gas-liquid mixtures, and foams. This paper presented a study that focused on gas-liquid mixtures. The purpose of this paper was to express two-phase flow in vertical wellbores, and determine required flow rates for liquid and gas phase by considering formation pressure and hole cleaning properties. It was assumed that the liquid phase is the major contributor for cuttings transport, and that the gas phase only influences the bottom hole pressure. The paper introduced a mechanistic model for estimating the hydraulic behaviour of gas-liquid mixture drilling fluids under different flow patterns. Based on the bottom hole pressure and effective hole cleaning point of view, an algorithm was proposed for estimating the optimum required flow rates for liquid and gas phases based on the introduced mechanistic model. The model also predicts the required backpressure that must be applied. It was concluded that since the liquid flow rate is only dependent on proper hole cleaning, gas flow rate can be adjusted to achieve a bottomhole pressure equal to formation pressure. Also, backpressure should not be kept constant at the same value for static and dynamic conditions. Otherwise, bottomhole pressure cannot be kept constant. 14 refs., 9 figs., 1 appendix.

  1. Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

    Science.gov (United States)

    Zouache, Moussa A.; Eames, Ian; Samsudin, Amir

    2016-01-01

    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac0.67, where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma. PMID:26990431

  2. Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

    KAUST Repository

    Fiscaletti, D.

    2016-10-24

    The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor e(i), with the vorticity vector omega, is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors vertical bar e(i) . (omega) over cap vertical bar are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e(1), in contrast to the global tendency for omega to be aligned in parallelwith the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008)]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between omega and nonlocal e(1) and that the strongly swirling worms are kinematically significant to this process.

  3. A relationship between salivary flow rates and Candida counts in patients with xerostomia

    Science.gov (United States)

    Nadig, Suchetha Devendrappa; Ashwathappa, Deepak Timmasandra; Manjunath, Muniraju; Krishna, Sowmya; Annaji, Araleri Gopalkrishna; Shivaprakash, Praveen Kunigal

    2017-01-01

    Context: Most of the adult population is colonized by Candida in their oral cavity. The process of colonization depends on several factors, including the interaction between Candida and salivary proteins. Therefore, salivary gland hypofunction may alter the oral microbiota and increase the risk for opportunistic infections, such as candidiasis. Hence, it is necessary to evaluate the relationship between salivary flow rates (SFRs) and Candida colony counts in the saliva of patients with xerostomia. Aims: This study aims to determine and evaluate the relationship between SFRs and Candida colony forming units (CFUs) in patients with xerostomia. Settings and Design: This study was a descriptive study. Subjects and Methods: The study participants were taken from the patients attending outpatient department in a private dental college. Fifty patients, who reported xerostomia in a questionnaire of the symptoms of xerostomia, were selected. Chewing stimulated whole saliva samples were collected from them and their SFRs were assessed. Saliva samples were inoculated in the Sabouraud dextrose agar culture media for 24–48 h, and Candida CFUs were counted. Statistical Analysis Used: Chi-squared test was used to analyze the data. Results: There was a significant inverse relationship between salivary flow and candida CFUs count when patients with high colony counts were analyzed (cutoff point of 400 or greater CFU/mL). Females had less SFR than males. Most of the patients who had hyposalivation were taking medication for the underlying systemic diseases. Candida albicans was the most frequent species. Conclusions: There was a significantly negative correlation between SFRs and Candida CFUs in the patients with xerostomia. PMID:28932047

  4. Salivary flow rate, buffer capacity, and urea concentration in adolescents with type 1 diabetes mellitus.

    Science.gov (United States)

    Saes Busato, Ivana Maria; Antoni, Carlos Cesar De; Calcagnotto, Thiago; Ignácio, Sérgio Aparecido; Azevedo-Alanis, Luciana Reis

    2016-12-01

    The objective of the study was to analyze salivary flow rate, urea concentration, and buffer capacity in adolescents with type 1 diabetes mellitus (type 1 DM) in two different stages. This study was performed on adolescents (14-19 years), allocated between two groups: type 1 DM group comprised 32 adolescents with type 1 DM, and non-type 1 DM group comprised 32 nondiabetics. The adolescents in type 1 DM group were evaluated at a baseline (T0) and after 15 months (T1), and those in non-type 1 DM group were only evaluated at T0. Diabetic status was determined by glycosylated hemoglobin (GHb) and capillary glucose tests. Measurement of salivary flow was performed by means of stimulated saliva (SSFR) collection. The buffer capacity (BC) was determined, and analysis of urea salivary concentration was performed using the colorimetric method. At T0, there were significant differences between diabetics and nondiabetics for SSFR and BC (p0.05). BC at T0 was 4.8, and at T1, it was 3.9 (p=0.000). Urea concentration mean value had a significant decrease at T1 (28.13) compared with T0 (34.88) (p=0.013). There was a negative correlation between SSFR and urea salivary concentration at both T0 (r=-0.426, p≤0.05) and T1 (r=-0.601, p≤0.01). In adolescents with type 1 DM, hyposalivation at T0 was associated with an increase in urea salivary concentration. At T1, hyposalivation was associated with a reduction in BC, and an increase in salivary urea.

  5. Effect of Flow Rate and Disc Area Increment on the Efficiency of Rotating Biological Contactor for Treating Greywater

    Directory of Open Access Journals (Sweden)

    Ashfaq Ahmed Pathan

    2015-04-01

    Full Text Available The performance of greywater treatment through RBC (Rotating Biological Contactor is related to many factors including rotational speed of disc, surface area of the media, thickness of biological film; quality and flow rate of influent. The plastic media provides surface for biological slime. The slime is rotated alternatively into the settled wastewater and then into atmosphere to provide aerobic conditions for the microorganisms. In this study the performance of RBC is investigated at different flow rates and disk areas of media by introducing additional discs on the shaft of RBC. Initially efficiency of the RBC was observed on six flow rates at the disc area of 9.78m2. Furthermore optimized three flow rates were used to augment the disk area. The efficiency of RBC system was improved significantly at disk area of 11.76m2 and flow rate of 20 L/h. Under these conditions the removal of BOD5 (Biochemical Oxygen Demand COD (Chemical Oxygen Demand and TSS (Total Suspended Solid was observed 83, 57 and 90% respectively

  6. Optimization of carbon dioxide supply in raceway reactors: Influence of carbon dioxide molar fraction and gas flow rate.

    Science.gov (United States)

    Duarte-Santos, T; Mendoza-Martín, J L; Acién Fernández, F G; Molina, E; Vieira-Costa, J A; Heaven, S

    2016-07-01

    Influence of CO2 composition and gas flow rate to control pH in a pilot-scale raceway producing Scenedesmus sp. was studied. Light and temperature determined the biomass productivity whereas neither the CO2 molar fraction nor the gas flow rate used influenced it; because pH was always controlled and carbon limitation did not take place. The CO2 molar fraction and the gas flow rate influenced carbon loss in the system. At low CO2 molar fraction (2-6%) or gas flow rate (75-100l·min(-1)) the carbon efficiency in the sump was higher than 95%, 85% of the injected carbon being transformed into biomass. Conversely, at high CO2 molar fraction (14%) or gas flow rate (150l·min(-1)) the carbon efficiency in the sump was lower than 67%, 32% of the carbon being fixed as biomass. Analysis here reported allows the pH control to be optimized and production costs to be reduced by optimizing CO2 efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The Measurements of Water Flow Rate in the T-shape Microchannels Based on the Scanning Micro-PIV Technique

    Science.gov (United States)

    Han, W.; Wang, H. L.; Xu, M.

    2011-09-01

    In this study, the scanning microfluidic particle image velocimetry (scanning micro-PIV) technique is used to measure the water flow rate in a T-shape microchannel with the inlet and outlet width being 300 μm and 200 μm, respectively. The standard flow rates controlled by the syringe pump are ranging from 3.508 to 11.693 μL/min. The quasi-three-dimensional velocities at the branch point of the T-shape microchannel are constructed by measuring the two-dimensional velocities on 11 fluid layers from the bottom of microchannel to the top. Based on this, the flow rates are calculated by the discrete integration of velocity distributions on the cross-section of microchannel. The relative errors of the flow rates of the inlet and outlet are all within 3%, and we conclude that the main factors affecting the measurement precision of flow rate include the wall roughness of the microchannel, the spatial resolution of microscopic system and the algorithm of velocity evaluation.

  8. Flow Time Analysis of Load Management Late Arrival Discrete Time Queueing System with Dual Service Rate Using Hypogeometrical Distribution

    Directory of Open Access Journals (Sweden)

    Syed Asif Ali Shah

    2012-01-01

    Full Text Available Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypogeometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities.

  9. Cash Flows versus Accounting Earnings in Managing Exchange Rate Exposures: An Empirical Study of Non-Financial Companies

    DEFF Research Database (Denmark)

    Aabo, Tom

    Financial theory argues that companies should manage cash flows and not accounting earnings when they hedge exchange rate exposures. Still, empirical evidence shows that a number of companies choose to manage accounting earnings. This empirical study of Danish, non-financial companies finds (1......) that when hedging the majority of companies expect to add value to their company by avoiding financial distress (reduce down side risk), (2) that when hedging managing cash flows versus managing accounting earnings as a first priority splits the companies in two, (3) a lack of difference (except...... for profitability) in company characteristics between the group of companies that manage cash flows versus the group of companies that manage accounting earnings as a first priority. The decision in real business on whether to manage cash flows or accounting earnings when hedging exchange rate exposures seems...

  10. Comparison of virtual unenhanced CT images of the abdomen under different iodine flow rates.

    Science.gov (United States)

    Li, Yongrui; Li, Ye; Jackson, Alan; Li, Xiaodong; Huang, Ning; Guo, Chunjie; Zhang, Huimao

    2017-01-01

    To assess the effect of varying iodine flow rate (IFR) and iodine concentration on the quality of virtual unenhanced (VUE) images of the abdomen obtained with dual-energy CT. 94 subjects underwent unenhanced and triphasic contrast-enhanced CT scan of the abdomen, including arterial phase, portal venous phase, and delayed phase using dual-energy CT. Patients were randomized into 4 groups with different IFRs or iodine concentrations. VUE images were generated at 70 keV. The CT values, image noise, SNR and CNR of aorta, portal vein, liver, liver lesion, pancreatic parenchyma, spleen, erector spinae, and retroperitoneal fat were recorded. Dose-length product and effective dose for an examination with and without plain phase scan were calculated to assess the potential dose savings. Two radiologists independently assessed subjective image quality using a five-point scale. The Kolmogorov-Smirnov test was used first to test for normal distribution. Where data conformed to a normal distribution, analysis of variance was used to compare mean HU values, image noise, SNRs and CNRs for the 4 image sets. Where data distribution was not normal, a nonparametric test (Kruskal-Wallis test followed by stepwise step-down comparisons) was used. The significance level for all tests was 0.01 (two-sided) to allow for type 2 errors due to multiple testing. The CT numbers (HU) of VUE images showed no significant differences between the 4 groups (p > 0.05) or between different phases within the same group (p > 0.05). VUE images had equal or higher SNR and CNR than true unenhanced images. VUE images received equal or lower subjective image quality scores than unenhanced images but were of acceptable quality for diagnostic use. Calculated dose-length product and estimated dose showed that the use of VUE images in place of unenhanced images would be associated with a dose saving of 25%. VUE images can replace conventional unenhanced images. VUE images are not affected by varying iodine

  11. Prediction of heating rate controlled viscous flow activation energy during spark plasma sintering of amorphous alloy powders

    Science.gov (United States)

    Paul, Tanaji; Harimkar, Sandip P.

    2017-07-01

    The viscous flow behavior of Fe-based amorphous alloy powder during isochronal spark plasma sintering was analyzed under the integrated theoretical background of the Arrhenius and directional structural relaxation models. A relationship between viscous flow activation energy and heating rate was derived. An extension of the pertinent analysis to Ti-based amorphous alloys confirmed the broad applicability of such a relationship for predicting the activation energy for sintering below the glass transition temperature (T g) of the amorphous alloy powders.

  12. A comparison of flow rates and pressure profiles for N-sequential inlets and three related seal configurations

    Science.gov (United States)

    Hendricks, R. C.

    1984-01-01

    Experimental and analytical results are presented for choked flows of fluid nitrogen over a range of reduced inlet stagnation temperatures (from 0.67 to ambient) and reduced inlet stagnation pressures to 2. Flow rate and pressure profile comparisons are made between N aligned sequential orifice inlets, a 33-tooth labyrinth seal, a 3-step seal, a cylindrical seal and the classic venturi. Seal effectiveness appears strongly dependent on upstream losses and geometry configuration.

  13. Effects on fuel spray characteristics and vaporization on energy release rates and flow field structure in a dump combustor

    Science.gov (United States)

    Bowman, C. T.; Hanson, R. K.; Vandsburger, U.; Allen, M. G.; McManus, K. R.

    1986-10-01

    An experimental investigation of the effects of fuel spray characteristics, specifically droplet size and extent of prevaporization, on energy release rate and flow field structure in a liquid-fueled dump combustor is in progress. Visualization and measurment of the spray characteristics and of the reacting flow field are carried out using high-speed schlieren photography and planar imaging techniques. An important element of the research is development of these imaging techniques for two-phase reacting flows. Progress to date is described in the development of several imaging techniques and initial results from experiments in the dump combustor.

  14. Simulation of parameters of hydraulic drive with volumetric type controller

    Science.gov (United States)

    Mulyukin, V. L.; Boldyrev, A. V.; Karelin, D. L.; Belousov, A. M.

    2017-09-01

    The article presents a mathematical model of volumetric type hydraulic drive controller that allows to calculate the parameters of forward and reverse motion. According to the results of simulation static characteristics of rod’s speed and the force of the hydraulic cylinder rod were built and the influence of the angle of swash plate of the controller at the characteristics profile is shown. The results analysis showed that the proposed controller allows steplessly adjust the speed□ц of hydraulic cylinder’s rod motion and the force developed on the rod without the use of flow throttling.

  15. In Vivo Real Time Volumetric Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Rasmussen, Morten Fischer; Brandt, Andreas Hjelm

    2015-01-01

    Synthetic aperture (SA) imaging can be used to achieve real-time volumetric ultrasound imaging using 2-D array transducers. The sensitivity of SA imaging is improved by maximizing the acoustic output, but one must consider the limitations of an ultrasound system, both technical and biological....... This paper investigates the in vivo applicability and sensitivity of volumetric SA imaging. Utilizing the transmit events to generate a set of virtual point sources, a frame rate of 25 Hz for a 90° x 90° field-of-view was achieved. Data were obtained using a 3.5 MHz 32 x 32 elements 2-D phased array...... transducer connected to the experimental scanner (SARUS). Proper scaling is applied to the excitation signal such that intensity levels are in compliance with the U.S. Food and Drug Administration regulations for in vivo ultrasound imaging. The measured Mechanical Index and spatial-peak- temporal...

  16. Effects of Bell Speed and Flow Rate on Evaporation of Water Spray from a Rotary Bell Atomizer

    Directory of Open Access Journals (Sweden)

    Rajan Ray

    2015-05-01

    Full Text Available A phase doppler anemometer (PDA was used to determine the effects of evaporation on water spray for three rotary bell atomizer operational variable parameters: shaping air, bell speed and liquid flow. Shaping air was set at either 200 standard liters per minute (L/min or 300 L/min, bell speed was set to 30, 40 or 50 thousand rotations per minute (krpm and water flow rate was varied between 100, 200 or 300 cubic centimeters per minute (cm3/min. The total evaporation between 22.5 and 37.5 cm from the atomizer (cm3/s was calculated for all the combinations of those variables. Evaporation rate increased with higher flow rate and bell speed but no statistically significant effects were obtained for variable shaping air on interactions between parameters.

  17. Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

    Directory of Open Access Journals (Sweden)

    Jafari Mohammad Javad

    2012-12-01

    Full Text Available Abstract The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p 3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream.

  18. Taguchi Method for Development of Mass Flow Rate Correlation using Hydrocarbon Refrigerant Mixture in Capillary Tube

    Directory of Open Access Journals (Sweden)

    Shodiya Sulaimon

    2014-07-01

    Full Text Available The capillary tube is an important control device used in small vapor compression refrigeration systems such as window air-conditioners, household refrigerators and freezers. This paper develops a non-dimensional correlation based on the test results of the adiabatic capillary tube for the mass flow rate through the tube using a hydrocarbon refrigerant mixture of 89.3% propane and 10.7% butane (HCM. The Taguchi method, a statistical experimental design approach, was employed. This approach explores the economic benefit that lies in studies of this nature, where only a small number of experiments are required and yet valid results are obtained. Considering the effects of the capillary tube geometry and the inlet condition of the tube, dimensionless parameters were chosen. The new correlation was also based on the Buckingham Pi theorem. This correlation predicts 86.67% of the present experimental data within a relative deviation of -10% to +10%. The predictions by this correlation were also compared with results in published literature.

  19. Effect of swimming on peak expiratory flow rate of atopic children.

    Science.gov (United States)

    Bemanian, Mohammad Hassan; Shirkhoda, Shima; Nakhjavani, Mina; Mozafari, Habibeh

    2009-06-01

    This study was conducted to evaluate the role of swimming on mechanic of lung in healthy individual and patients with asthma. A total 76 girls who took part in the course of regular swimming session three day per week for eight weeks enrolled in this study. All of them completed ISAAC written questionnaire and individual who was suspected of asthma or other atopic diseases was referred to allergist for more evaluation. Peak expiratory flow rate was recorded for participants at beginning, one hour after swimming and two months later. According to ISAAC questionnaire 35.4% had asthma or other atopic diseases. Increase in PEFR more than 20% of personal best was seen in 21.9% after one hour swimming and in 27.6% after two months. Increase in PEFR was significant in healthy individual and asthmatic patients and obese but was not significant in patients with allergic rhinitis or eczema. This study suggests swimming in indoor pool is useful for patients with asthma in spite of potential toxic role of chlorine in exacerbation of asthma symptoms and lung mechanics.

  20. Lung volume and expiratory flow rates from pre- to post-puberty.

    Science.gov (United States)

    Smith, Joshua R; Emerson, Sam R; Kurti, Stephanie P; Gandhi, Kirti; Harms, Craig A

    2015-08-01

    The purpose was to determine if the airways and lungs grow disproportionately from pre- to post-puberty in boys and girls. We hypothesized that the airways grow at a slower rate than lung volume (i.e. dysanapsis growth) during puberty and boys would exhibit more dysanaptic growth compared to girls. Twenty-one pre-pubescent children [11 boys (pre 10.1 ± 0.5 years, post 15.3 ± 0.5 years); 10 girls (pre 9.4 ± 1.0 years, post 14.1 ± 1.0 years)] performed pulmonary function tests (PFTs) ~5 years ago from an original cohort of 40 children. These 21 children performed PFTs, which included forced vital capacity (FVC) and forced expiratory flow at 50 % FVC (FEF50). Static pressure at 50 % of FVC [Pst(L)50 %] was estimated based on age. Dysanapsis ratio (DR) was calculated [FEF50 × FVC(-1) × Pst(L) 50 % (-1) ]. Maturation status was determined via Tanner stages. Stage of maturation was not different (p > 0.05) between boys and girls (4.2 ± 0.6 stage vs. 3.7 ± 0.7 stage, respectively). FVC and FEF50 increased (p 0.05) from pre- to post-puberty. FEF50 and FVC significantly increased and DR decreased (p 0.05) compared to girls. These data suggest that dysanaptic growth occurs during puberty and that it is not different between boys and girls.

  1. Analysis of Improved Urinary Peak Flow Rates After Robot-Assisted Radical Prostatectomy.

    Science.gov (United States)

    Skarecky, Douglas; Gordon, Adam; Babaian, Kara N; Dhaliwal, Harleen; Morales, Blanca; Ahlering, Thomas E

    2015-10-01

    Longitudinal assessment of prostatic obstruction has historically been assessed with urinary peak flow rates (PFR). In this observational study, we assess the impact of prostate removal on preoperative and postoperative PFRs after robot-assisted radical prostatectomy (RARP). A single surgeon (TA) performed RARPs between 2002 and 2007. Men underwent routine preoperative uroflowmetric testing: 550 qualified for analysis with a sufficient voided volume (VV) of 150 mL preoperatively and at least once postoperatively. Continence and self-assessed American Urological Association (AUA) symptom and urinary quality of life (QoL) questionnaires were queried. Uroflows were analyzed preoperatively, short-term (3-15 mos), long-term (>2 y), and by age decades, lower urinary tract symptoms (LUTS) groups, and pathologic weight cohorts. AUA and QoL scores improved from 8.1 and 1.6 at baseline to 4.4 and 1.0 at intermediate-term follow-up, P5 years follow- up (all P5 years (P50%) by 3 months. After RARP, the average PFR was reset to 25-30 mL/s, and these results were seen across all age, LUTS, and prostate weight groups; the gains remained stable 2 to 4 years after operation.

  2. Analysis of arrayed nanocapacitor formed on nanorods by flow-rate interruption atomic layer deposition

    Science.gov (United States)

    Lin, Bo-Cheng; Ku, Ching-Shun; Lee, Hsin-Yi; Chakroborty, Subhendu; Wu, Albert T.

    2017-12-01

    Flow-rate interruption (FRI) atomic layer deposition (ALD) technique was adopted to fabricate AZO/Al2O3/AZO thin film on a ZnO nanorod array template at low temperature. The high quality amorphous dielectric Al2O3 layer was deposited at 50 °C. The template with an average of 0.73 μm in length was made by a simple hydrothermal method on a c-plane sapphire with an AZO seed layer. Using Polystyrene (PS) microspheres were served as a mask to form vertical and well-aligned ZnO nanostructures. Field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) images show ALD to have achieved good step coverage and thickness control in the thin films structure coating. The capacitance density of the arrayed template nanocapacitor increased more than 100% than those of the thin film capacitor at an applied frequency of 10 kHz. These results suggest that the ZnO-arrayed template could enhance energy storage capability by providing significant surface area. This structure provides a concept for high surface-area nanocapacitor applications.

  3. On the consistency of flow rate color Doppler assessment for the internal jugular vein

    Directory of Open Access Journals (Sweden)

    Francesco Sisini

    2014-01-01

    Full Text Available Color Doppler methodology to assess the vessel blood flow rate is based on the time averaged velocity of the blood measured in the longitudinal plane and the cross sectional area measurement taken either in the longitudinal plane, by assuming circular cross sectional area, or in the transversal plane. The measurement option in longitudinal plane is based on the assumption of circular cross sectional area, while the transversal one needs to evaluate both time-averaged velocity and cross sectional area in the same vessel point. A precise and validated assessment methodology is still lacking. Four healthy volunteers underwent internal jugular vein colour Doppler scanning. The cross sectional area was assessed by means of B-mode imaging in the transversal plane all along the vessel cervical course. During this assessment, cross sectional area, major and minor axis of the vessel were measured and recorded. The distance between the internal jugular vein wall and the skin surface were measured together with the intra-luminal diameter and statistically correlated with the cross sectional area data. The internal jugular vein cross sectional area measured on the transversal plane were significantly different from the cross sectional area calculated using the assumption of circular shape. The intra-luminal distance showed high correlation with the measured cross sectional area. The proper anatomical point in the cross sectional area transversal measurement can be identified by using the internal jugular vein intra-luminal distance as landmark.

  4. A “twisted” microfluidic mixer suitable for a wide range of flow rate applications

    KAUST Repository

    Sivashankar, Shilpa

    2016-06-27

    This paper proposes a new “twisted” 3D microfluidic mixer fabricated by a laser writing/microfabrication technique. Effective and efficient mixing using the twisted micromixers can be obtained by combining two general chaotic mixing mechanisms: splitting/recombining and chaotic advection. The lamination of mixer units provides the splitting and recombination mechanism when the quadrant of circles is arranged in a two-layered serial arrangement of mixing units. The overall 3D path of the microchannel introduces the advection. An experimental investigation using chemical solutions revealed that these novel 3D passive microfluidic mixers were stable and could be operated at a wide range of flow rates. This micromixer finds application in the manipulation of tiny volumes of liquids that are crucial in diagnostics. The mixing performance was evaluated by dye visualization, and using a pH test that determined the chemical reaction of the solutions. A comparison of the tornado-mixer with this twisted micromixer was made to evaluate the efficiency of mixing. The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software. Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed. The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

  5. Determination of Multiphase Flow Meter Reliability and Development of Correction Charts for the Prediction of Oilfield Fluid Flow Rates

    Directory of Open Access Journals (Sweden)

    Samuel S. MOFUNLEWI

    2008-06-01

    Full Text Available The aim of field testing of Multiphase Flow Meter (MPFM is to show whether its accuracy compares favourably with that of the Test Separator in accurately measuring the three production phases (oil, gas and water as well as determining meter reliability in field environment. This study evaluates field test results of the MPFM as compared to reference conventional test separators. Generally, results show that MPFM compares favourably with Test Separator within the specified range of accuracy.At the moment, there is no legislation for meter proving technique for MPFM. However, this study has developed calibration charts that can be used to correct and improve meter accuracy.

  6. Effects of inlet radius and bell mouth radius on flow rate and sound quality of centrifugal blower

    Energy Technology Data Exchange (ETDEWEB)

    Son, Pham Ngoc; Kim, Jae Won; Byun, S. M. [Sunmoon University, Asan (Korea, Republic of); Ahn, E. Y. [Hanbat National University, Daejeon (Korea, Republic of)

    2012-05-15

    The effect of inlet radius and bell mouth radius on flow rate of centrifugal blower were numerically simulated using a commercial CFD program, FLUENT. In this research, a total of eight numerical models were prepared by combining different values of bell mouth radii and inlet radii (the cross section of bell mouth was chosen as a circular arc in this research). The frozen rotor method combined with a realizable k-epsilon turbulence model and non-equilibrium wall function was used to simulate the three-dimensional flow inside the centrifugal blowers. The inlet radius was then revealed to have significant impact on flow rate with the maximum difference between analyzed models was about 4.5% while the bell mouth radius had about 3% impact on flow rate. Parallel experiments were carried out to confirm the results of CFD analysis. The CFD results were thereafter validated owning to the good agreement between CFD results and the parallel experiment results. In addition to performance analysis, noise experiments were carried out to analyze the dependence of sound quality on inlet radius and bell mouth radius with different flow rate. The noise experiment results showed that the loudness and sharpness value of different models were quite similar, which mean the inlet radius and the bell mouth radius didn't have a clear impact on sound quality of centrifugal blower.

  7. A field comparison of BTEX mass flow rates based on integral pumping tests and point scale measurements.

    Science.gov (United States)

    Dietze, Michael; Dietrich, Peter

    2011-03-25

    Measuring contaminant flow rates at control cross sections is the most accurate method to evaluate natural attenuation processes in the saturated subsurface. In most instances, point scale measurement is the method of choice due to practical reasons and cost factors. However, at many field sites, the monitoring network is too sparse for a reliable estimation of contaminant and groundwater flow rates. Therefore, integral pumping tests have been developed as an alternative. In this study, we compare mass flow rates obtained by integral pumping test results and point scale data. We compare results of both methods with regard to uncertainties due to estimation errors and mass flow estimations based on two different point scale networks. The differences between benzene and groundwater flow rate estimates resulting from point scale samples and integral pumping tests were 6.44% and 6.97%, respectively, demonstrating the applicability of both methods at the site. Point scale-based data, especially with use of cost efficient Direct-Push technique, can be applied to show the contaminant distribution at a site and may be followed by a denser point scale network or an integral method. Nevertheless, a combination of both methods decreases uncertainties. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Magnetic resonance measurement of blood and CSF flow rates with phase contrast--normal values, repeatability and CO2 reactivity.

    Science.gov (United States)

    Piechnik, Stefan K; Summers, Paul E; Jezzard, Peter; Byrne, James V

    2008-01-01

    Similarity in flow pulsatility has been proposed as a basis for semi-automated segmentation of vessel lumens for MR-based flow measurement, but re-examinations of salient aspects of the methodology have not been widely reported. 12 normal control subjects underwent repeated (3*Baseline+1*5%CO2) phase contrast measurements of CSF flow through the cerebral aqueduct and foramen magnum, and CBF through the 6 large cranial vessels at the level of the 1st vertebra. Average flows were calculated for regions temporally correlated (0.3 < or = Rthreshold < or = 0.95) to user defined seed points and their 3 x 3 neighbours. Arterial CBF averaged 710ml/min, with low variability (+/- 4%/17%, intra-individual/group CV respectively) and was the only flow to respond significantly to 5%/mmHg CO2. Venous outflow was much smaller (298ml/min +/- 10%/ 72%), possibly due to the weak venous pulse and variable venous anatomy. Average CSF flows exceeded the classical 0.4ml/min CSF production rate and were highly variable--aqueduct: 0.6ml/min (+/- 50%/93%), foramen magnum: -2.7ml/min (+/- 158%/226%). This preliminary analysis identified procedural steps that can improve the accuracy and repeatability of MR flow measurements, but the process remains user-dependent for the weakly pulsatile foramen magnum CSF and venous flows where variability remains a significant confound even to relatively large perturbations such as CO2 administration.

  9. Influence of flow rate on different properties of diamond-like nanocomposite thin films grown by PECVD

    Directory of Open Access Journals (Sweden)

    T. S. Santra

    2012-06-01

    Full Text Available Diamond-like nanocomposite (DLN thin films were deposited on pyrex glass substrate using different flow rate of haxamethyldisiloxane (HMDSO based liquid precursor with nitrogen gas as a glow discharged decomposition by plasma enhanced chemical vapor deposition (PECVD technique. The significant influence of different precursor flow rates on refractive index and thickness of the DLN films was measured by using spectroscopic filmatrics and DEKTAK profilometer. Optical transparency of the DLN thin films was analyzed by UV-VIS-NIR spectrometer. FTIR spectroscopy, provides the information about shifted bonds like SiC2, Si-C, Si-O, C-C, Si-H, C-H, N-H, and O-H with different precursor flow rate. We have estimated the hardness of the DLN films from Raman spectroscopy using Gaussian deconvolution method and tried to investigate the correlation between hardness, refractive index and thickness of the films with different precursor flow rates. The composition and surface morphology of the DLN films were investigated by X-ray photo electron spectroscopy (XPS and atomic force microscopy (AFM respectively. We have analyzed the hardness by intensity ratio (ID/IG of D and G peaks and correlates with hardness measurement by nanoindentation test where hardness increases from 27.8 μl/min to 80.6μl/min and then decreases with increase of flow rate from 80.6μl/min to 149.5μl/min. Finally, we correlates different parameters of structural, optical and tribological properties like film-thickness, refractive index, light transmission, hardness, surface roughness, modulus of elasticity, contact angle etc. with different precursor flow rates of DLN films.

  10. Salivary flow rates measured during radiation therapy in head and neck cancer patients: a pilot study assessing salivary sediment formation.

    Science.gov (United States)

    Chambers, Mark S; Tomsett, Kelley L; Artopoulou, Ioli I; Garden, Adam S; El-Naggar, Adel K; Martin, Jack W; Keene, Harris J

    2008-08-01

    Xerostomia often occurs in patients being managed for head and neck cancer who receive radiation therapy. Although accurate salivary sampling can be therapeutically important to measure during radiation, sampling errors can occur because of salivary sediments. Determining the impact that salivary sediments have on measured salivary flow rates during radiation is important for management of patients. The purpose of this study was to assess the magnitude of error associated with the inclusion of nonsalivary components (sediment) in the calculation of whole stimulated saliva flow rates prior to and during radiation therapy (SS and SSR) in patients with head and neck cancer. Whole paraffin-stimulated saliva was collected in large-mouth centrifuge tubes from 20 patients with head and neck cancer prior to and during the third week of radiation therapy. Gravimetric methods were used to calculate the flow rates at g/5 min. After centrifugation, supernatant saliva was removed and the sediment was oven-dried to remove residual moisture. Sediment weight was subtracted from the original weight of saliva specimens and flow rates were recalculated. Means and standard deviations were determined and flow rate differences before (BC) and after (AC) sediment correction were evaluated statistically with the paired t test (alpha=.05). A nonparametric analysis of the flow rate data with the Wilcoxon matched-pairs signed-ranks test was also used to examine the magnitude and direction of the intrapair (BC-AC) differences (alpha=.05). On average, salivary sediment contributed less than 1% of the total uncorrected weight of saliva prior to radiation therapy. In specimens collected during radiation therapy, sediment contributed an average of 14% of the total uncorrected weight and as high as 95.4% in 1 patient. Sediment percentages were 20% and higher in 4 patients. In the Wilcoxon analysis, 19 out of 20 paired BC and AC flow rates were higher in the BC group in the SS and SSR samples. The

  11. The effects of flow rate and concentration on nitrobenzene removal in abiotic and biotic zero-valent iron columns

    DEFF Research Database (Denmark)

    Yin, Weizhao; Wu, Jinhua; Huang, Weilin

    2016-01-01

    Abstract This study investigated the effects of varying nitrobenzene (NB) loadings via increasing flow rate or influent NB concentration mode on the removal efficiency in zero-valent iron (ZVI) columns sterilized (abiotic) or preloaded with acclimated microorganisms (biotic). It was shown...... flow rates and influent NB concentrations were at 0.5 mL min− 1 and 80 μmol L− 1 for the abiotic column and 2.0 mL min-1 and 240 μmol L− 1 for the biotic column, respectively. This study indicated that microorganisms not only enhanced overall reduction of NB, but also facilitated NB sequestration...

  12. The effect of mixing rates on the formation and growth of condensation aerosols in a model stagnation flow

    KAUST Repository

    Alshaarawi, Amjad

    2015-03-01

    A steady, laminar stagnation flow configuration is adopted to investigate numerically the interaction between condensing aerosol particles and gas-phase transport across a canonical mixing layer. The mixing rates are varied by adjusting the velocity and length scales of the stagnation flow parametrically. The effect of mixing rates on particle concentration, polydispersity, and mean droplet diameter is explored and discussed. This numerical study reveals a complex response of the aerosol to varying flow times. Depending on the flow time, the variation of the particle concentration in response to varying mixing rates falls into one of the two regimes. For fast mixing rates, the number density and volume fraction of the condensing particles increase with residence time (nucleation regime). On the contrary, for low mixing rates, number density decreases with residence time and volume fraction reaches a plateau (condensation regime). It is shown that vapor scavenging by the aerosol phase is key to explaining the transition between these two regimes. The results reported here are general and illustrate genuine features of the evolution of aerosols forming by condensation of supersaturated vapor from heat and mass transport across mixing layers.

  13. Evaluation of hemolysis in microcatheter directed blood infusion at different flow rates for transarterial salvage reperfusion: In-vitro study.

    Science.gov (United States)

    Froelich, Jens J; Ray, Udayan; Monkhorst, Jessica; Marwick, Thomas H; Hardikar, Ashutosh; Harle, Robin; Carr, Michael W

    2015-01-01

    Microcatheter directed blood reperfusion is an endovascular salvage option for acute cerebral artery occlusions. It has not been investigated whether this technique may be associated with hemolysis. Analysis of hemolysis during blood infusion through different microcatheters and infusion rates to assess related risks. Four microcatheters with different inner diameters were perfused with blood samples at three infusion rates. Hemolytic markers including lactate-dehydrogenase (LDH) and haptoglobin were analyzed. Samples before and after blood infusion were compared using Student's t-test. Flow-related degree of hemolysis was analyzed with regression analysis. Resulting shear stress was calculated and correlated with LDH and haptoglobin. Significant increase of LDH and decrease of haptoglobin was found after blood reperfusion through small microcatheters at progressive flow rates (pflow rates (p>0.05). Correlation between shear stress, LDH and haptoglobin was r=0.86 and r=0.75, respectively. Progressive hemolysis occurs during blood perfusion of small lumen microcatheters at increasing flow rates. This phenomenon may be related to turbulent flow, exposure time and increased shear stress. Larger microcatheters did not induce hemolysis and may be the preferred choice for stroke reperfusion.

  14. Ni foam cathode enables high volumetric H{sub 2} production in a microbial electrolysis cell

    Energy Technology Data Exchange (ETDEWEB)

    Jeremiasse, Adriaan W. [Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden (Netherlands); Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, P.O. Box 8038, 6700 EK Wageningen (Netherlands); Hamelers, Hubertus V.M. [Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Saakes, Michel [Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden (Netherlands); Magneto Special Anodes B.V., Calandstraat 109, 3125 BA Schiedam (Netherlands); Buisman, Cees J.N. [Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden (Netherlands); Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands)

    2010-12-15

    Valuable, ''green'' H{sub 2} can be produced with a microbial electrolysis cell (MEC). To achieve a high volumetric production rate of high purity H{sub 2}, a continuous flow MEC with an anion exchange membrane, a flow through bioanode and a flow through Ni foam cathode was constructed. At an electrical energy input of 2.6 kWh m{sup -3} H{sub 2} (applied cell voltage: 1.00 V), this MEC was able to produce over 50 m{sup 3} H{sub 2} m{sup -3} MEC d{sup -1} (22.8 {+-} 0.1 A m{sup -2}). The MEC had a low cathode overpotential compared to an MEC with Pt-based cathode, because of the high specific surface area of Ni foam (128 m{sup 2} m{sup -2} projected area). The MEC performance however, decreased during 32 days of operation due to an increase in anode and cathode overpotentials. Scaling likely caused the increase in anode overpotential, but it remained unclear what caused the increase in cathode overpotential. (author)

  15. Capillary Flow Rates in the Duodenum of Pediatric Ulcerative Colitis Patients Are Increased and Unrelated to Inflammation.

    Science.gov (United States)

    Zaidi, Deenaz; Churchill, Lucas; Huynh, Hien Q; Carroll, Matthew W; Persad, Rabin; Wine, Eytan

    2017-09-01

    Inflammatory bowel diseases (IBD), including Crohn disease (CD) and ulcerative colitis (UC), are chronic pediatric disorders. Changes in vasculature are described in IBD, but these could be secondary to inflammation and the role in pathogenesis is poorly understood. Assessing circulatory changes in typically unaffected sites in IBD (eg, duodenum), when inflammation is absent, can identify vascular changes associated with pathogenesis. The aim of the study is to measure capillary flow rates in duodenal mucosa using probe-based confocal laser endomicroscopy (pCLE) during endoscopy in children with IBD. Images of villi with visible blood vessels obtained using pCLE were captured as video sequences. Capillary flow rate (mm/s) was calculated by dividing the distance travelled by blood cells by the duration of the sequence. Flow rates were correlated with various clinical parameters. Forty-five patients (22 non-IBD, 14 CD, 9 UC) were included in the study. Duodenal capillary flow rates were significantly higher in UC patients (0.75 ± 0.07 mm/s) as compared to non-IBD (0.57 ± 0.03) and CD (0.65 ± 0.04). There was no correlation between serum hemoglobin and albumin, disease activity indices, serum inflammatory markers, and capillary flow rates in patients. This pilot study shows, for the first time, increased capillary blood flow in the duodenum of UC patients that was unrelated to inflammatory markers or disease activity. Thus, early vascular changes can be assessed using pCLE during endoscopy.

  16. Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

    Science.gov (United States)

    Yan, Wen; Economou, Demetre J.

    2017-10-01

    A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

  17. Flow

    DEFF Research Database (Denmark)

    2009-01-01

    Flow er en positiv, koncentreret tilstand, hvor al opmærksomhed er samlet om en bestemt aktivitet, som er så krævende og engagerende, at man må anvende mange mentale ressourcer for at klare den. Tidsfornemmelsen forsvinder, og man glemmer sig selv. 'Flow' er den første af en række udsendelser om...

  18. Forecasting the Nysa Kłodzka flow rate in order to predict the available flow for a run-off-river (ROR power plant

    Directory of Open Access Journals (Sweden)

    Jurasz Jakub

    2017-01-01

    Full Text Available Hydroelectricity is generally perceived as a stable and predictable power source. However ROR power plant without reservoir energy output is mainly driven by changing flow rate. This study applies artificial neural networks to create flow rate forecasts with one hour lead time. Forecasting models were built for Nysa Kłodzka catchment which possesses significant potential for new hydropower plants development as well as leads to frequent floods. The best of the obtained model gives satisfactory results both in terms of root mean square error (0.6379 m3/s as well as Nash-Sutcliffe performance indicator (0.9978. Obtained results were compared with currently used forecasting models and were proven to be superior.

  19. Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

    Science.gov (United States)

    Wong, Ronnie J.; Jivraj, Jamil; Vuong, Barry; Ramjist, Joel; Sun, Cuiru; Huang, Yize; Yang, Victor X. D.

    2015-03-01

    The use of gas assistance in laser machining hard materials is well established in manufacturing but not in the context of surgery. Laser cutting of osseous tissue in the context of neurosurgery can benefit from gas-assist but requires an understanding of flow and pressure effects to minimize neural tissue damage. In this study we acquire volumetric flow rates through a gas nozzle on the spinal cord, with dura and without dura.