Assessment for hydrodynamic masses of HANARO flow tubes

International Nuclear Information System (INIS)

Ryu, Jeong Soo; Cho, Yeong Garp; Kim, Doo Kie; Woo, Jong Sug; Park, Jin Ho

2000-06-01

The effect of hydrodynamic masses is investigated in dynamic characteristics and seismic response analyses of the submerged HANARO hexagonal flow tubes. Consistent hydrodynamic masses of the surrounding water are evaluated by the prepared program using the finite element method, in which arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered. Also lumped hydrodynamic masses are calculated using simple formula applied to hexagonal flow tubes in the infinite fluid. Modal analyses and seismic response spectrum analyses were performed using hydrodynamic masses obtained by the finite element method and the simple formula. The results of modal analysis were verified by comparing the results measured from modal tests. And the displacement results of the seismic response spectrum analysis were assessed by comparing the consistent and the lumped hydrodynamic masses obtained by various methods. Finally practical criteria based on parametric studies are proposed as the lumped hydrodynamic masses for HANARO flow tubes

Assessment for hydrodynamic masses of HANARO flow tubes

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jeong Soo; Cho, Yeong Garp; Kim, Doo Kie; Woo, Jong Sug; Park, Jin Ho

2000-06-01

The effect of hydrodynamic masses is investigated in dynamic characteristics and seismic response analyses of the submerged HANARO hexagonal flow tubes. Consistent hydrodynamic masses of the surrounding water are evaluated by the prepared program using the finite element method, in which arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered. Also lumped hydrodynamic masses are calculated using simple formula applied to hexagonal flow tubes in the infinite fluid. Modal analyses and seismic response spectrum analyses were performed using hydrodynamic masses obtained by the finite element method and the simple formula. The results of modal analysis were verified by comparing the results measured from modal tests. And the displacement results of the seismic response spectrum analysis were assessed by comparing the consistent and the lumped hydrodynamic masses obtained by various methods. Finally practical criteria based on parametric studies are proposed as the lumped hydrodynamic masses for HANARO flow tubes.

Development of a miniaturized mass-flow meter for an axial flow blood pump based on computational analysis.

Science.gov (United States)

Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

2011-09-01

In order to monitor the condition of patients with implantable left ventricular assist systems (LVAS), it is important to measure pump flow rate continuously and noninvasively. However, it is difficult to measure the pump flow rate, especially in an implantable axial flow blood pump, because the power consumption has neither linearity nor uniqueness with regard to the pump flow rate. In this study, a miniaturized mass-flow meter for discharged patients with an implantable axial blood pump was developed on the basis of computational analysis, and was evaluated in in-vitro tests. The mass-flow meter makes use of centrifugal force produced by the mass-flow rate around a curved cannula. An optimized design was investigated by use of computational fluid dynamics (CFD) analysis. On the basis of the computational analysis, a miniaturized mass-flow meter made of titanium alloy was developed. A strain gauge was adopted as a sensor element. The first strain gauge, attached to the curved area, measured both static pressure and centrifugal force. The second strain gauge, attached to the straight area, measured static pressure. By subtracting the output of the second strain gauge from the output of the first strain gauge, the mass-flow rate was determined. In in-vitro tests using a model circulation loop, the mass-flow meter was compared with a conventional flow meter. Measurement error was less than ±0.5 L/min and average time delay was 0.14 s. We confirmed that the miniaturized mass-flow meter could accurately measure the mass-flow rate continuously and noninvasively.

Role of cerebral blood flow in extreme breath holding.

Science.gov (United States)

Bain, Anthony R; Ainslie, Philip N; Hoiland, Ryan L; Willie, Chris K; MacLeod, David B; Madden, Dennis; Maslov, Petra Zubin; Drviš, Ivan; Dujić, Željko

2016-01-01

The role of cerebral blood flow (CBF) on a maximal breath-hold (BH) in ultra-elite divers was examined. Divers (n = 7) performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg). Arterial blood gases and CBF were measured prior to (baseline), and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO 2 ) by about 26% (p tension was higher following oral administration of indomethacin compared to control (4.05 ± 0.45 vs. 3.44 ± 0.32 kPa). The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01). These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H + washout, and therefore central chemoreceptive drive to breathe, rather than to CDO 2 .

Gaseous Nitrogen Orifice Mass Flow Calculator

Science.gov (United States)

Ritrivi, Charles

2013-01-01

The Gaseous Nitrogen (GN2) Orifice Mass Flow Calculator was used to determine Space Shuttle Orbiter Water Spray Boiler (WSB) GN2 high-pressure tank source depletion rates for various leak scenarios, and the ability of the GN2 consumables to support cooling of Auxiliary Power Unit (APU) lubrication during entry. The data was used to support flight rationale concerning loss of an orbiter APU/hydraulic system and mission work-arounds. The GN2 mass flow-rate calculator standardizes a method for rapid assessment of GN2 mass flow through various orifice sizes for various discharge coefficients, delta pressures, and temperatures. The calculator utilizes a 0.9-lb (0.4 kg) GN2 source regulated to 40 psia (.276 kPa). These parameters correspond to the Space Shuttle WSB GN2 Source and Water Tank Bellows, but can be changed in the spreadsheet to accommodate any system parameters. The calculator can be used to analyze a leak source, leak rate, gas consumables depletion time, and puncture diameter that simulates the measured GN2 system pressure drop.

Semiempirical method of determining flow coefficients for pitot rake mass flow rate measurements

Science.gov (United States)

Trefny, C. J.

1985-01-01

Flow coefficients applicable to area-weighted pitot rake mass flow rate measurements are presented for fully developed, turbulent flow in an annulus. A turbulent velocity profile is generated semiempirically for a given annulus hub-to-tip radius ratio and integrated numerically to determine the ideal mass flow rate. The calculated velocities at each probe location are then summed, and the flow rate as indicated by the rake is obtained. The flow coefficient to be used with the particular rake geometry is subsequently obtained by dividing the ideal flow rate by the rake-indicated flow rate. Flow coefficients ranged from 0.903 for one probe placed at a radius dividing two equal areas to 0.984 for a 10-probe area-weighted rake. Flow coefficients were not a strong function of annulus hub-to-tip radius ratio for rakes with three or more probes. The semiempirical method used to generate the turbulent velocity profiles is described in detail.

Compact Mass Flow Meter Based on a Micro Coriolis Flow Sensor

Directory of Open Access Journals (Sweden)

Remco Wiegerink

2013-03-01

Full Text Available In this paper we demonstrate a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 1 g/h (for water at a pressure drop < 1 bar. It has a zero stability of 2 mg/h and an accuracy of 0.5% reading for both liquids and gases. The temperature drift between 10 and 50 °C is below 1 mg/h/°C. The meter is robust, has standard fluidic connections and can be read out by means of a PC or laptop via USB. Its performance was tested for several common gases (hydrogen, helium, nitrogen, argon and air and liquids (water and isopropanol. As in all Coriolis mass flow meters, the meter is also able to measure the actual density of the medium flowing through the tube. The sensitivity of the measured density is ~1 Hz.m3/kg.

MEMS-based Micro Coriolis mass flow sensor

NARCIS (Netherlands)

Haneveld, J.; Brouwer, Dannis Michel; Mehendale, A.; Zwikker, R.; Lammerink, Theodorus S.J.; de Boer, Meint J.; Wiegerink, Remco J.

2008-01-01

We have realized a micromachined micro Coriolis flow sensor consisting of a silicon nitride resonant tube of 40 μm diameter and 1.2 μm wall thickness. First measurements with both gas and liquid flows have demonstrated an unprecedented mass flow resolution in the order of 10 mg/hr at a full scale

A mass conservative numerical solution of vertical water flow and mass transport equations in unsaturated porous media

International Nuclear Information System (INIS)

Lim, S.C.; Lee, K.J.

1993-01-01

The Galerkin finite element method is used to solve the problem of one-dimensional, vertical flow of water and mass transport of conservative-nonconservative solutes in unsaturated porous media. Numerical approximations based on different forms of the governing equation, although they are equivalent in continuous forms, can result in remarkably different solutions in an unsaturated flow problem. Solutions given by a simple Galerkin method based on the h-based Richards equation yield a large mass balance error and an underestimation of the infiltration depth. With the employment of the ROMV (restoration of main variable) concept in the discretization step, the mass conservative numerical solution algorithm for water flow has been derived. The resulting computational schemes for water flow and mass transport are applied to sandy soil. The ROMV method shows good mass conservation in water flow analysis, whereas it seems to have a minor effect on mass transport. However, it may relax the time-step size restriction and so ensure an improved calculation output. (author)

Investigation of the specific mass flow rate distribution in pipes supplied with a pulsating flow

Energy Technology Data Exchange (ETDEWEB)

Olczyk, Aleksander [Institute of Turbomachinery, Technical University of Lodz, Wolczanska 219/223, 90-924 Lodz (Poland)], E-mail: aolczyk@p.lodz.pl

2009-08-15

A pulsating flow is typical of inlet and exhaust pipes of internal combustion engines and piston compressors. Unsteady flow phenomena are especially important in the case of turbocharged engines, because dynamic effects occurring in the exhaust pipe can affect turbine operation conditions and performance. One of the basic parameters describing the unsteady flow is a transient mass flow rate related to the instantaneous flow velocity, which is usually measured by means of hot-wire anemometers. For the flowing gas, it is more appropriate to analyze the specific mass flow rate {phi}{sub m} = {rho}v, which takes into account also variations in the gas density. In order to minimize the volume occupied by measuring devices in the control section, special double-wire sensors for the specific mass flow rate (CTA) and temperature (CCT) measurement were applied. The article describes procedures of their calibration and measurement. Different forms of calibration curves are analyzed as well in order to match the approximation function to calibration points. Special attention is paid to dynamic phenomena related to the resonance occurring in a pipe for characteristic frequencies depending on the pipe length. One of these phenomena is a reverse flow, which makes it difficult to interpret properly the recorded CTA signal. Procedures of signal correction are described in detail. To verify the measurements, a flow field investigation was carried out by displacing probes radially and determining the profiles of the specific mass flow rate under the conditions of a steady and pulsating flow. The presence and general features of a reverse flow, which was identified experimentally, were confirmed by 1-D unsteady flow calculations.

Investigation of the specific mass flow rate distribution in pipes supplied with a pulsating flow

International Nuclear Information System (INIS)

Olczyk, Aleksander

2009-01-01

A pulsating flow is typical of inlet and exhaust pipes of internal combustion engines and piston compressors. Unsteady flow phenomena are especially important in the case of turbocharged engines, because dynamic effects occurring in the exhaust pipe can affect turbine operation conditions and performance. One of the basic parameters describing the unsteady flow is a transient mass flow rate related to the instantaneous flow velocity, which is usually measured by means of hot-wire anemometers. For the flowing gas, it is more appropriate to analyze the specific mass flow rate φ m = ρv, which takes into account also variations in the gas density. In order to minimize the volume occupied by measuring devices in the control section, special double-wire sensors for the specific mass flow rate (CTA) and temperature (CCT) measurement were applied. The article describes procedures of their calibration and measurement. Different forms of calibration curves are analyzed as well in order to match the approximation function to calibration points. Special attention is paid to dynamic phenomena related to the resonance occurring in a pipe for characteristic frequencies depending on the pipe length. One of these phenomena is a reverse flow, which makes it difficult to interpret properly the recorded CTA signal. Procedures of signal correction are described in detail. To verify the measurements, a flow field investigation was carried out by displacing probes radially and determining the profiles of the specific mass flow rate under the conditions of a steady and pulsating flow. The presence and general features of a reverse flow, which was identified experimentally, were confirmed by 1-D unsteady flow calculations.

Mass transfer effects in feeder flow-accelerated corrosion wall thinning

International Nuclear Information System (INIS)

Pietralik, J.

2008-01-01

Flow conditions play a dominant role in Flow-Accelerated Corrosion (FAC) under certain conditions, e.g., in CANDU feeders. While chemistry and materials set the overall potential for FAC, flow conditions determine the local distribution of wall thinning. Recent plant data of feeders and laboratory tests confirms that there is a close relationship between local flow conditions, expressed by mass transfer coefficient, and FAC rate in CANDU feeder bends. The knowledge of local effects can be useful for minimizing the number of inspected components, predicting the location of the highest FAC rate for a given piping component, and determining what components or feeders should be replaced. A similar evaluation applies also to FAC in heat transfer equipment such as heat exchangers and steam generators. The objective of this paper is to examine the relationship between FAC rate and local mass transfer parameters. For FAC where the flow is dominant, the FAC rate is proportional to mass flux of ferrous ions. The mass flux is the product of the mass transfer coefficient and the concentration difference, or degree of saturation. The mass transfer coefficient describes the intensity of the transport of corrosion products (ferrous ions) from the oxide-water interface into the bulk water. Therefore, this parameter can be used for predicting the local distribution of FAC rate in the mass-transfer controlled FAC. The degree of saturation reduces the mass flux, thus reducing the FAC rate. This effect can be significant in long piping, e.g., in outlet feeders. The paper presents plant and laboratory evidence for the relationship between local mass transfer conditions and the FAC rate. It shows correlations for mass transfer coefficient in components that are highly susceptible to FAC and most important flow parameters that affect mass transfer coefficient. The role of surface roughness, wall shear stress, and local turbulence is also discussed. (author)

Analysis of lignans in Magnoliae Flos by turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry.

Science.gov (United States)

Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2016-04-01

In this study, a method coupling turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry was developed for analyzing the lignans in Magnoliae Flos. By the online pretreatment of turbulent flow chromatography solid-phase extraction, the impurities removal and analytes concentration were automatically processed, and the lignans were separated rapidly and well. Seven lignans of Magnoliae Flos including epieudesmin, magnolin, 1-irioresinol-B-dimethyl ether, epi-magnolin, fargesin aschantin, and demethoxyaschantin were identified by comparing their retention behavior, UV spectra, and mass spectra with those of reference substances or literature data. The developed method was validated, and the good results showed that the method was not only automatic and rapid, but also accurate and reliable. The turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry method holds a high potential to become an effective method for the quality control of lignans in Magnoliae Flos and a useful tool for the analysis of other complex mixtures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PET/CT-guided percutaneous liver mass biopsies and ablations: Targeting accuracy of a single 20 s breath-hold PET acquisition

International Nuclear Information System (INIS)

Shyn, P.B.; Tatli, S.; Sahni, V.A.; Sadow, C.A.; Forgione, K.; Mauri, G.; Morrison, P.R.; Catalano, P.J.; Silverman, S.G.

2014-01-01

Aim: To determine whether a single 20 s breath-hold positron-emission tomography (PET) acquisition obtained during combined PET/computed tomography (CT)-guided percutaneous liver biopsy or ablation procedures has the potential to target 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG)-avid liver masses as accurately as up to 180 s breath-hold PET acquisitions. Materials and methods: This retrospective study included 10 adult patients with 13 liver masses who underwent FDG PET/CT-guided percutaneous biopsies (n = 5) or ablations (n = 5). PET was acquired as nine sequential 20 s, monitored, same-level breath-hold frames and CT was acquired in one monitored breath-hold. Twenty, 40, 60, and 180 s PET datasets were reconstructed. Two blinded readers marked tumour centres on randomized PET and CT datasets. Three-dimensional spatial localization differences between PET datasets and either 180 s PET or CT were analysed using multiple regression analyses. Statistical tests were two-sided and p < 0.05 was considered significant. Results: Targeting differences between 20 s PET and 180 s PET ranged from 0.7–20.3 mm (mean 5.3 ± 4.4 mm; median 4.3) and were not statistically different from 40 or 60 s PET (p = 0.74 and 0.91, respectively). Targeting differences between 20 s PET and CT ranged from 1.4–36 mm (mean 9.6 ± 7.1 mm; median 8.2 mm) and were not statistically different from 40, 60, or 180 s PET (p = 0.84, 0.77, and 0.35, respectively). Conclusion: Single 20 s breath-hold PET acquisitions from PET/CT-guided percutaneous liver procedures have the potential to target FDG-avid liver masses with equivalent accuracy to 180 s summed, breath-hold PET acquisitions and may facilitate strategies that improve image registration and shorten procedure times

Investigation of the Flow Rate Effect Upstream of the Constant-Geometry Throttle on the Gas Mass Flow

Directory of Open Access Journals (Sweden)

Yu. M. Timofeev

2016-01-01

Full Text Available The turbulent-flow throttles are used in pneumatic systems and gas-supply ones to restrict or measure gas mass flow. It is customary to install the throttles in joints of pipelines (in teejoints and cross tees or in joints of pipelines with pneumatic automation devices Presently, in designing the pneumatic systems and gas-supply ones a gas mass flow through a throttle is calculated by a known equation derived from the Saint-Venant-Vantсel formula for the adiabatic flow of ideal gas through a nozzle from an unrestrictedly high capacity tank. Neglect of gas velocity at the throttle inlet is one of the assumptions taken in the development of the above equation. As may be seen in practice, in actual systems the diameters of the throttle and the pipe wherein it is mounted can be commensurable. Neglect of the inlet velocity therewith can result in an error when determining the required throttle diameter in design calculation and a flow rate in checking calculation, as well as when measuring a flow rate in the course of the test. The theoretical study has revealed that the flow velocity at the throttle inlet is responsible for two parameter values: the outlet flow velocity and the critical pressure ratio, which in turn determine the gas mass flow value. To calculate the gas mass flow, the dependencies are given in the paper, which allow taking into account the flow rate at the throttle inlet. The analysis of obtained dependencies has revealed that the degree of influence of inlet flow rate upon the mass flow is defined by two parameters: pressure ratio at the throttle and open area ratio of the throttle and the pipe wherein it is mounted. An analytical investigation has been pursued to evaluate the extent to which the gas mass flow through the throttle is affected by the inlet flow rate. The findings of the investigation and the indications for using the present dependencies are given in this paper. By and large the investigation allowed the

Flow and mass transfer downstream of an orifice under flow accelerated corrosion conditions

International Nuclear Information System (INIS)

Ahmed, Wael H.; Bello, Mufatiu M.; El Nakla, Meamer; Al Sarkhi, Abdelsalam

2012-01-01

Highlights: ► Mass transfer downstream of orifices was numerically and experimentally investigated. ► The surface wear pattern is measured and used to validate the present numerical results. ► The maximum mass transfer coefficient found to occur at approximately 2–3 pipe diameters downstream of the orifice. ► The FAC wear rates were correlated with the turbulence kinetic energy and wall mass transfer in terms of Sherwood number. ► The current study offered very useful information for FAC engineers for better preparation of nuclear plant inspection scope. - Abstract: Local flow parameters play an important role in characterizing flow accelerated corrosion (FAC) downstream of sudden area change in power plant piping systems. Accurate prediction of the highest FAC wear rate locations enables the mitigation of sudden and catastrophic failures, and the improvement of the plant capacity factor. The objective of the present study is to evaluate the effect of the local flow and mass transfer parameters on flow accelerated corrosion downstream of an orifice. In the present study, orifice to pipe diameter ratios of 0.25, 0.5 and 0.74 were investigated numerically by solving the continuity and momentum equations at Reynolds number of Re = 20,000. Laboratory experiments, using test sections made of hydrocal (CaSO 4 ·½H 2 O) were carried out in order to determine the surface wear pattern and validate the present numerical results. The numerical results were compared to the plants data as well as to the present experiments. The maximum mass transfer coefficient found to occur at approximately 2–3 pipe diameters downstream of the orifice. This location was also found to correspond to the location of elevated turbulent kinetic energy generated within the flow separation vortices downstream of the orifice. The FAC wear rates were correlated with the turbulence kinetic energy and wall mass transfer in terms of Sherwood number. The current study found to offer very

Quantification of the transient mass flow rate in a simplex swirl injector

International Nuclear Information System (INIS)

Khil, Taeock; Kim, Sunghyuk; Cho, Seongho; Yoon, Youngbin

2009-01-01

When a heat release and acoustic pressure fluctuations are generated in a combustor by irregular and local combustions, these fluctuations affect the mass flow rate of the propellants injected through the injectors. In addition, variations of the mass flow rate caused by these fluctuations bring about irregular combustion, which is associated with combustion instability, so it is very important to identify a mass variation through the pressure fluctuation on the injector and to investigate its transfer function. Therefore, quantification of the variation of the mass flow rate generated in a simplex swirl injector via the injection pressure fluctuation was the subject of an initial study. To acquire the transient mass flow rate in the orifice with time, the axial velocity of flows and the liquid film thickness in the orifice were measured. The axial velocity was acquired through a theoretical approach after measuring the pressure in the orifice. In an effort to understand the flow area in the orifice, the liquid film thickness was measured by an electric conductance method. In the results, the mass flow rate calculated from the axial velocity and the liquid film thickness measured by the electric conductance method in the orifice was in good agreement with the mass flow rate acquired by the direct measuring method in a small error range within 1% in the steady state and within 4% for the average mass flow rate in a pulsated state. Also, the amplitude (gain) of the mass flow rate acquired by the proposed direct measuring method was confirmed using the PLLIF technique in the low pressure fluctuation frequency ranges with an error under 6%. This study shows that our proposed method can be used to measure the mass flow rate not only in the steady state but also in the unsteady state (or the pulsated state). Moreover, this method shows very high accuracy based on the experimental results

Role of cerebral blood flow in extreme breath holding

Directory of Open Access Journals (Sweden)

Bain Anthony R.

2016-01-01

Full Text Available The role of cerebral blood flow (CBF on a maximal breath-hold (BH in ultra-elite divers was examined. Divers (n = 7 performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg. Arterial blood gases and CBF were measured prior to (baseline, and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO2 by about 26% (p < 0.01. Indomethacin reduced maximal BH time from 339 ± 51 to 319 ± 57 seconds (p = 0.04. In both conditions, the CDO2 remained unchanged from baseline to the termination of apnea. At BH termination, arterial oxygen tension was higher following oral administration of indomethacin compared to control (4.05 ± 0.45 vs. 3.44 ± 0.32 kPa. The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01. These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H+ washout, and therefore central chemoreceptive drive to breathe, rather than to CDO2.

Orifice Mass Flow Calculation in NASA's W-8 Single Stage Axial Compressor Facility

Science.gov (United States)

Bozak, Richard F.

2018-01-01

Updates to the orifice mass flow calculation for the W-8 Single Stage Axial Compressor Facility at NASA Glenn Research Center are provided to include the effect of humidity and incorporate ISO 5167. A methodology for including the effect of humidity into the inlet orifice mass flow calculation is provided. Orifice mass flow calculations provided by ASME PTC-19.5-2004, ASME MFC-3M-2004, ASME Fluid Meters, and ISO 5167 are compared for W-8's atmospheric inlet orifice plate. Differences in expansion factor and discharge coefficient given by these standards give a variation of about +/- 75% mass flow except for a few cases. A comparison of the calculations with an inlet static pressure mass flow correlation and a fan exit mass flow integration using test data from a 2017 turbofan rotor test in W-8 show good agreement between the inlet static pressure mass flow correlation, ISO 5167, and ASME Fluid Meters. While W-8's atmospheric inlet orifice plate violates the pipe diameter limit defined by each of the standards, the ISO 5167 is chosen to be the primary orifice mass flow calculation to use in the W-8 facility.

Fiber optic liquid mass flow sensor and method

Science.gov (United States)

Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)

2010-01-01

A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.

Compact mass flow meter based on a micro coriolis flow sensor

NARCIS (Netherlands)

Sparreboom, Wouter; van de Geest, Jan; Katerberg, Marcel; Postma, F.M.; Haneveld, J.; Groenesteijn, Jarno; Lammerink, Theodorus S.J.; Wiegerink, Remco J.; Lötters, Joost Conrad

2013-01-01

In this paper we demonstrate a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 1 g/h (for water at a pressure drop < 1 bar). It has a zero stability of 2 mg/h and an accuracy of 0.5% reading for both liquids and gases. The temperature drift between 10 and 50 °C is below 1

The Determinants and Implications of Corporate Cash Holdings

OpenAIRE

Tim Opler; Lee Pinkowitz; Rene Stulz; Rohan Williamson

1997-01-01

We examine the determinants and implications of holdings of cash and marketable" securities by publicly traded U.S. firms in the 1971-1994 period. Firms with strong growth" opportunities and riskier cash flows hold relatively high ratios of cash to total assets. Firms" that have the greatest access to the capital markets (e.g. large firms and those with credit" ratings) tend to hold lower ratios of cash to total assets. These results are consistent with the" view that firms hold liquid assets...

Compact mass flow meter based on a micro Coriolis flow sensor

NARCIS (Netherlands)

Sparreboom, Wouter; Katerberg, M.R.; Lammerink, Theodorus S.J.; Postma, F.M.; Haneveld, J.; Groenesteijn, Jarno; Wiegerink, Remco J.; Lötters, Joost Conrad

2012-01-01

In this paper we present a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 2 g/h (for water at a pressure drop of 2 bar). It has a zero stability of 2 mg/h and an accuracy of 0.5% reading. The temperature drift between 10 and 50 ºC is below 1 mg/h/ºC. The meter is robust,

Engineering analysis of mass flow rate for turbine system control and design

International Nuclear Information System (INIS)

Yoo, Yong H.; Suh, Kune Y.

2011-01-01

Highlights: → A computer code is written to predict the steam mass flow rate through valves. → A test device is built to study the steam flow characteristics in the control valve. → Mass flow based methodology eases the programming and experimental procedures. → The methodology helps express the characteristics of each device of a turbine system. → The results can commercially be used for design and operation of the turbine system. - Abstract: The mass flow rate is determined in the steam turbine system by the area formed between the stem disk and the seat of the control valve. For precise control the steam mass flow rate should be known given the stem lift. However, since the thermal hydraulic characteristics of steam coming from the generator or boiler are changed going through each device, it is hard to accurately predict the steam mass flow rate. Thus, to precisely determine the steam mass flow rate, a methodology and theory are developed in designing the turbine system manufactured for the nuclear and fossil power plants. From the steam generator or boiler to the first bunch of turbine blades, the steam passes by a stop valve, a control valve and the first nozzle, each of which is connected with piping. The corresponding steam mass flow rate can ultimately be computed if the thermal and hydraulic conditions are defined at the stop valve, control valve and pipes. The steam properties at the inlet of each device are changed at its outlet due to geometry. The Compressed Adiabatic Massflow Analysis (CAMA) computer code is written to predict the steam mass flow rate through valves. The Valve Engineered Layout Operation (VELO) test device is built to experimentally study the flow characteristics of steam flowing inside the control valve with the CAMA input data. The Widows' Creek type control valve was selected as reference. CAMA is expected to be commercially utilized to accurately design and operate the turbine system for fossil as well as nuclear power

Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow

International Nuclear Information System (INIS)

Colli, A.N.; Bisang, J.M.

2013-01-01

Highlights: • A convergent laminar flow enhances and becomes more uniform the mass-transfer rate. • The mass-transfer rate is increased under convergent turbulent flow conditions. • The mass-transfer rate under convergent laminar flow can be theoretically predicted. • A convergent duct improves the reactor behaviour and the concept is easily applicable. -- Abstract: A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4 mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions

Micro Coriolis mass flow sensor driven by external piezo ceramic

NARCIS (Netherlands)

Zeng, Yaxiang; Groenesteijn, Jarno; Alveringh, Dennis; Wiegerink, Remco J.; Lötters, Joost Conrad

2017-01-01

We have realized a micro Coriolis mass flow meter driven with an external piezo ceramic. The piezoelec tric ceramic is glued on top of sensor chip with a inertial weight on top of the piezo ceramic. Its ability to measure mass flow is characterized by a laser Doppler vibrometer. Our measurement with

Inflation, operating cycle, and cash holdings

Directory of Open Access Journals (Sweden)

Yanchao Wang

2014-12-01

Full Text Available A corporate cash-holding strategy is a trade-off between the costs and benefits of holding cash. At the macrolevel, firms are inclined to adjust and optimize their cash-holding strategies in response to changes in purchasing power due to inflation. At the microlevel, the operating cycle, which indicates the speed and turnover of corporate cash flow, also influences the corporate cash-holding strategy. Firms flexibly adjust their cash-holding strategies in response to changes in the internal and external environment, which is referred to as the cash adjustment strategy. We examine these predicted relationships using a sample of listed firms in China’s stock market over the 1998–2009 period. Consistent with our predictions, the empirical results indicate a significant negative association between cash holdings and the CPI, but the relationship is reversed when the CPI reaches a certain level. There is also a U-shaped relationship between operating cycle and cash holdings, and this relationship is similarly influenced by changes in the inflation level. In examining the macroeconomic environment and microlevel firm-specific characteristics simultaneously, our findings supplement the literature on firms’ cash-holding strategies and provide theoretical and practical implications.

Hardware implementation of the ORNL fissile mass flow monitor

International Nuclear Information System (INIS)

McEvers, J.; Sumner, J.; Jones, R.; Ferrell, R.; Martin, C.; Uckan, T.; March-Leuba, J.

1998-01-01

This paper provides an overall description of the implementation of the Oak Ridge National Laboratory (ORNL) Fissile Mass Flow Monitor, which is part of a Blend Down Monitoring System (BDMS) developed by the US Department of Energy (DOE). The Fissile Mass Flow Monitor is designed to measure the mass flow of fissile material through a gaseous or liquid process stream. It consists of a source-modulator assembly, a detector assembly, and a cabinet that houses all control, data acquisition, and supporting electronics equipment. The development of this flow monitor was first funded by DOE/NE in September 95, and an initial demonstration by ORNL was described in previous INMM meetings. This methodology was chosen by DOE/NE for implementation in November 1996, and the hardware/software development is complete. Successful BDMS installation and operation of the complete BDMS has been demonstrated in the Paducah Gaseous Diffusion Plant (PGDP), which is operated by Lockheed Martin Utility Services, Inc. for the US Enrichment Corporation and regulated by the Nuclear Regulatory Commission. Equipment for two BDMS units has been shipped to the Russian Federation

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.

PACTOLUS, Nuclear Power Plant Cost and Economics by Discounted Cash Flow Method. CLOTHO, Mass Flow Data Calculation for Program PACTOLUS

International Nuclear Information System (INIS)

Haffner, D.R.

1976-01-01

1 - Description of problem or function: PACTOLUS is a code for computing nuclear power costs using the discounted cash flow method. The cash flows are generated from input unit costs, time schedules and burnup data. CLOTHO calculates and communicates to PACTOLUS mass flow data to match a specified load factor history. 2 - Method of solution: Plant lifetime power costs are calculated using the discounted cash flow method. 3 - Restrictions on the complexity of the problem - Maxima of: 40 annual time periods into which all costs and mass flows are accumulated, 20 isotopic mass flows charged into and discharged from the reactor model

Governance mechanisms, investment opportunity set and SMEs cash holdings

OpenAIRE

Belghitar, Yacine; Khan, James

2013-01-01

This study analyses the effect of firm characteristics and governance mechanisms on cash holdings for a sample of UK SMEs. The results show that UK SMEs with greater cash flow volatility and institutional investors hold more cash; whereas levered and dividend paying SMEs with non-executive ownership hold less cash. We also find that ownership structure is significant only in explaining the cash holdings for firms with high growth investment opportunities, and leverage is only significant in e...

The Determinants of Corporate Cash Holdings- An Empirical study from UK Firms

OpenAIRE

GUO, YI

2013-01-01

Cash holding is most important financial decision in the company management strategy. In this dissertation, the determinants of corporate cash holdings in UK non-financial publicly traded firms over the period from 2003 to 2012 are investigated. Our study finds that growth opportunities and cash flow and cash flow variability are positively associated with the level of corporate cash holdings, while firm size, leverage, net working capital, bank debt and dividend payment have negative impact ...

Blowdown mass flow measurements during the Power Burst Facility LOC-11C test

International Nuclear Information System (INIS)

Broughton, J.M.; MacDonald, P.E.

1979-01-01

An interpretation and evaluation of the two-phase coolant mass flow measurements obtained during Test LOC-11C performed in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory (INEL) are presented. Although a density gradient existed within the pipe between 1 and 6 s, the homogeneous flow model used to calculate the coolant mass flow from the measured mixture density, momentum flux, and volumetric flow was found to be generally satisfactory. A cross-sectional average density was determined by fitting a linear density gradient through the upper and lower chordal densities obtained from a three-beam gamma densitometer and then combining the result with the middle beam density. The integrated measured coolant mass flow was subsequently found to be within 5% if the initial mass inventory of the PBF loss-of-coolant accident (LOCA) system. The posttest calculations using the RELAP4/MOD6 computer code to determine coolant mass flow for Test LOC-11C also agreed well with the measured data

The Holding Power of Anchors

Indian Academy of Sciences (India)

The efficiency of an anchor may be expressed as the ratio (holding force + weight of anchor). In dry sand .... the market at the beginning of the coming season in three sizes, namely 20, 35 and. 60 lb. These are ... Taylor frozen-flow hypothesis.

Modelling of a micro Coriolis mass flow sensor for sensitivity improvement

NARCIS (Netherlands)

Groenesteijn, Jarno; van de Ridder, Bert; Lötters, Joost Conrad; Wiegerink, Remco J.

2014-01-01

We have developed a multi-axis flexible body model with which we can investigate the behavior of (micro) Coriolis mass flow sensors with arbitrary channel geometry. The model has been verified by measurements on five different designs of micro Coriolis mass flow sensors. The model predicts the Eigen

Time resolved mass flow measurements for a fast gas delivery system

International Nuclear Information System (INIS)

Ruden, E.L.; Degnan, J.H.; Hussey, T.W.; Scott, M.C.; Graham, J.D.; Coffey, S.K.

1992-01-01

A technique is demonstrated whereby the delivered mass and flow rate vs. time of a short rise time gas delivery system may be accurately determined. The gas mass M which flows past a point in a gas delivery system by an arbitrary time t may be accurately measured if that point is sealed off within a time interval short compared to the mass flow time scale. If the ejected mass is allowed to equilibrate in a known volume after being cut off from its source, a conventional static pressure measurement before and after injection, and application of the ideal gas law suffices. Assuming reproducibility, a time history M(t) may be generated, allowing the flow rate vs. time dM(t)/dt to be determined. Mass flow measurements are presented for a fast delivery system in which the flow of argon through a 3.2 mm I.D., 0.76 mm thick copper tube is cut off by imploding (θ pinching) the tube using a single turn tungsten magnetic field coil. Pinch discharge parameters are 44 μf, 20 kV, 47 nH, 3.5 mΩ, 584 kA, and 8.63 ps current period. Optical measurements of the tube's internal area vs. time indicate that the tube is sealed 2 ps from the time the tube is still 90% open (7 μs from the start of pinch current). The pinch delay is varied from 500--1,500 ps from the valve trigger (0--1,000 ps from the start of gas flow). The mass injected into the test volume is ∼ 100 μg during this interval. The leak rate of the sealed tube results in a mass increase of only ∼ 0.1 μg by the time the pressure gauge stabilizes (6 s). Results are correlated with piezoelectric probe measurements of the gas flow and 2-D axisymmetric numerical simulations of the θ pinch process. Simulations of a θ pinch suitable for characterizing an annular supersonic nozzle typical of those used in gas puff z pinches are discussed

Response timescales for martian ice masses and implications for ice flow on Mars

DEFF Research Database (Denmark)

Koutnik, Michelle Rebecca; Waddington, E.D.; Winebrener, D.P.

2013-01-01

a predictable shape, which is a function of ice temperature, ice rheology, and surface mass-exchange rate. In addition, the time for surface-shape adjustment is shorter than the characteristic time for significant deformation or displacement of internal layers within a flowing ice mass; as a result, surface......On Earth and on Mars, ice masses experience changes in precipitation, temperature, and radiation. In a new climate state, flowing ice masses will adjust in length and in thickness, and this response toward a new steady state has a characteristic timescale. However, a flowing ice mass has...... topography is more diagnostic of flow than are internal-layer shapes. Because the shape of Gemina Lingula, North Polar Layered Deposits indicates that it flowed at some time in the past, we use its current topography to infer characteristics of those past ice conditions, or past climate conditions, in which...

Nuclear assay of coal. Volume 6. Mass flow devices for coal handling

International Nuclear Information System (INIS)

Anon.

1979-01-01

The mass of coal entering the boiler per unit time is an essential parameter for determinig the total rate of heat input. The mass flow rate of coal on a conveyor belt is generally determined as a product of the instantaneous mass of material on a short section of the belt and the belt velocity. Belt loading could be measured by conventional transducers incorporating mechanical or electromechanical weighers or by gamma-ray attenuation gauge. This report reviews the state of the art in mass flow devices for coal handling. The various methods are compared and commented upon. Special design issues are discussed relative to incorporating a mass flow measuring device in a Continuous On-Line Nuclear Analysis of Coal (CONAC) system

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

Science.gov (United States)

Abadeh, Aryan; Lew, Roger R

2013-11-01

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

Mass flow and evolution of UW Canis Majoris

International Nuclear Information System (INIS)

Kondo, Y.; Rahe, J.

1979-01-01

The far-UV spectrum of the eclipsing binary UW CMa (07f + 0-B) has earlier been utilized to derive a mass-loss rate of about 10 -6 to 10 -5 solar mass per year. The mass flow seems to be basically in the form of a stellar wing emanating from the 07f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed. (Auth.)

A new method for the measurement of two-phase mass flow rate using average bi-directional flow tube

International Nuclear Information System (INIS)

Yoon, B. J.; Uh, D. J.; Kang, K. H.; Song, C. H.; Paek, W. P.

2004-01-01

Average bi-directional flow tube was suggested to apply in the air/steam-water flow condition. Its working principle is similar with Pitot tube, however, it makes it possible to eliminate the cooling system which is normally needed to prevent from flashing in the pressure impulse line of pitot tube when it is used in the depressurization condition. The suggested flow tube was tested in the air-water vertical test section which has 80mm inner diameter and 10m length. The flow tube was installed at 120 of L/D from inlet of test section. In the test, the pressure drop across the average bi-directional flow tube, system pressure and average void fraction were measured on the measuring plane. In the test, fluid temperature and injected mass flow rates of air and water phases were also measured by a RTD and two coriolis flow meters, respectively. To calculate the phasic mass flow rates : from the measured differential pressure and void fraction, Chexal drift-flux correlation was used. In the test a new correlation of momentum exchange factor was suggested. The test result shows that the suggested instrumentation using the measured void fraction and Chexal drift-flux correlation can predict the mass flow rates within 10% error of measured data

Parametric amplification in a micro Coriolis mass flow sensor

NARCIS (Netherlands)

Groenesteijn, Jarno; Droogendijk, H.; Wiegerink, Remco J.; Lammerink, Theodorus S.J.; Lötters, Joost Conrad; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

2014-01-01

We report on the application of parametric amplification to a micro Coriolis mass flow sensor. We demonstrate that this mechanism allows for reduction of the system's power dissipation while retaining sensitivity to flow. By reducing this power dissipation, less heat will be transferred to the fluid

Design of mass flow rate measurement system for SST-1 superconducting magnet system

Energy Technology Data Exchange (ETDEWEB)

Varmora, P., E-mail: pvamora@ipr.res.in; Sharma, A.N.; Khristi, Y.; Prasad, U.; Patel, D.; Doshi, K.; Pradhan, S.

2016-11-15

Highlights: • Design of Venturi meter for SST-1 magnet system. • Details of Helium mass flow measurement system used in SST-1. • Instruments and measurement techniques for flow measurement. • VME based data acquisition system details and flow calculation and results from SST-1 campaigns. - Abstract: Superconducting Magnet System (SCMS) of Steady State Superconducting Tokamak – 1 (SST-1) is forced-flow cooled by a closed cycle 1.3 kW (at 4.5 K) class Helium Refrigerator cum Liquefier (HRL) system. An accurate measurement of helium mass flow rate in different coils is required to ensure the uniform cooling of the cold mass in the entire range of operating temperature (300 K to 4.5 K) and pressure (0.9–0.4 MPa). To meet this requirement, indigenously designed and fabricated venturi meters are installed on 27 different coils of SST-1 SCMS. A VME based Data Acquisition System (DAS) has been developed and used to acquire the flow measurement data from different flowmeters. The details of the design of venturi meter, its different measurement and signal conditioning components, the data acquisition system and the mass flow rate calculation method are described in this paper. The mass flow rate measurement data from cryogenic acceptance and SST-1 magnet commissioning experiments are also presented and discussed in this paper.

Design of mass flow rate measurement system for SST-1 superconducting magnet system

International Nuclear Information System (INIS)

Varmora, P.; Sharma, A.N.; Khristi, Y.; Prasad, U.; Patel, D.; Doshi, K.; Pradhan, S.

2016-01-01

Highlights: • Design of Venturi meter for SST-1 magnet system. • Details of Helium mass flow measurement system used in SST-1. • Instruments and measurement techniques for flow measurement. • VME based data acquisition system details and flow calculation and results from SST-1 campaigns. - Abstract: Superconducting Magnet System (SCMS) of Steady State Superconducting Tokamak – 1 (SST-1) is forced-flow cooled by a closed cycle 1.3 kW (at 4.5 K) class Helium Refrigerator cum Liquefier (HRL) system. An accurate measurement of helium mass flow rate in different coils is required to ensure the uniform cooling of the cold mass in the entire range of operating temperature (300 K to 4.5 K) and pressure (0.9–0.4 MPa). To meet this requirement, indigenously designed and fabricated venturi meters are installed on 27 different coils of SST-1 SCMS. A VME based Data Acquisition System (DAS) has been developed and used to acquire the flow measurement data from different flowmeters. The details of the design of venturi meter, its different measurement and signal conditioning components, the data acquisition system and the mass flow rate calculation method are described in this paper. The mass flow rate measurement data from cryogenic acceptance and SST-1 magnet commissioning experiments are also presented and discussed in this paper.

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

The fabrication of plastic cages for suspension in mass air flow racks.

Science.gov (United States)

Nielsen, F H; Bailey, B

1979-08-01

A cage for suspension in mass air flow racks was constructed of plastic and used to house rats. Little or no difficulty was encountered with the mass air flow rack-suspended cage system during the 4 years it was used for the study of trace elements.

UF6 fissile mass flow simulation at Oak Ridge National Laboratory

International Nuclear Information System (INIS)

Mihalczo, J.T.; March-Leuba, J.; Valentine, T.E.; Mattingly, J.K.; Uckan, T.; McEvers, J.A.

1997-01-01

Basis for measuring fissile mass flow in slurries, liquid, and gaseous streams is activation of a fissile stream by neutrons and then detection of delayed radiation from resulting fission products. This paper describes recent simulation measurements with the first prototype of the system for fissile mass flow measurements with HEU UF 6 gas for use in blenddown facilities. Theory was only 15% higher than actual measured; thus calibration factor would be 0.85. This simulation of HEU gas flow confirms well the understanding of the physical phenomena associated with this measurement system

Device for measurement of gas mass flow. Einrichtung zur Gasmassenstrommessung

Energy Technology Data Exchange (ETDEWEB)

Sass, W

1989-09-28

The invention is concerned with a device for the measurement of gas mass flow, particularly measuring air mass flow for vehicles with internal combustion engines, with a measurement bridge, in one branch of which a gas flow resistance, particularly a hot film sensor, with gas flowing round it, is connected in series with a measurement resistance and in another branch of which a compensation resistance measuring the gas temperature is connected in series with a fixed resistor, where the bridge differential voltage is measured in the zero branch of the measuring bridge and a control parameter is produced from this, in order to control a transistor valve situated in the bridge supply path of a DC voltage source via its control electrode until the bridge is balanced, and where the voltage at the measurement resistance after the bridge is balanced is used as a measure of the gas mass flow. In order to obtain exact results of measurement in spite of relatively high interference noise from the cables, it is proposed that an increased supply DC voltage appreciably decreasing the occurring interference noise from the cables should be produced from a small DC voltage and that the output of the DC/DC voltage converter should be connected to the control electrode of the transistor valve, so that the control parameter for the control electrode is derived from the raised DC supply voltage through reducers depending on the gas flow.

Shape signature based on Ricci flow and optimal mass transportation

Science.gov (United States)

Luo, Wei; Su, Zengyu; Zhang, Min; Zeng, Wei; Dai, Junfei; Gu, Xianfeng

2014-11-01

A shape signature based on surface Ricci flow and optimal mass transportation is introduced for the purpose of surface comparison. First, the surface is conformally mapped onto plane by Ricci flow, which induces a measure on the planar domain. Second, the unique optimal mass transport map is computed that transports the new measure to the canonical measure on the plane. The map is obtained by a convex optimization process. This optimal transport map encodes all the information of the Riemannian metric on the surface. The shape signature consists of the optimal transport map, together with the mean curvature, which can fully recover the original surface. The discrete theories of surface Ricci flow and optimal mass transportation are explained thoroughly. The algorithms are given in detail. The signature is tested on human facial surfaces with different expressions accquired by structured light 3-D scanner based on phase-shifting method. The experimental results demonstrate the efficiency and efficacy of the method.

The effect of virtual mass on the prediction of critical flow

International Nuclear Information System (INIS)

Cheng, L.; Lahey, R.T.; Drew, D.A.

1983-01-01

By observing the results in Fig. 4 and Fig. 5 we can see that virtual mass effects are important in predicting critical flow. However, as seen in Fig. 7a, in which all three flows are predicted to be critical (Δ=0), it is difficult to distinguish one set of conditions from the other by just considering the pressure profile. Clearly more detailed data, such as the throat void fraction, is needed for discrimination between these calculations. Moreover, since the calculated critical flows have been found to be sensitive to initial mass flux, and void fraction, careful measurements of those parameters are needed before accurate virtual mass parameters can be determined from these data. It can be concluded that the existing Moby Dick data is inadequate to allow one to deduce accurate values of the virtual mass parameters C/sub VM/ and λ. Nevertheless, more careful experiments of this type are uniquely suited for the determination of these important parameters. It appears that the use of a nine equation model, such as that discussed herein, coupled with more detailed accurate critical flow data is an effective means of determining the parameters in interfacial momentum transfer models, such as virtual mass effects, which are only important during strong spatial accelerations. Indeed, there are few other methods available which can be used for such determinations

Mass flow rate measurements in two-phase mixtrues with stagnation probes

International Nuclear Information System (INIS)

Fincke, J.R.; Deason, V.A.

1979-01-01

Applications of stagnation probes to the measurement of mass flow rate in two-phase flows are discussed. Descriptions of several stagnation devices, which have been evaluated at the Idaho National Engineering Laboratory, are presented along with modeling techniques and two-phase flow data

Virtual mass effects in two-phase flow. Topical report

International Nuclear Information System (INIS)

Cheng, L.Y.; Drew, D.A.; Lahey, R.T. Jr.

1978-03-01

The effect of virtual mass on phase separation during the acceleration of a two-phase mixture was studied. Virtual mass can be regarded as an induced inertia on the dispersed phase which is accelerating relative to the continuous phase, and it was found that the virtual mass acceleration is objective, implying an invariance with respect to reference frame. An objective form of the virtual acceleration was derived and required parameters were determined for limiting cases. Analyses determined that experiments on single bubble nozzle/diffuser flow cannot readily discriminate between various virtual mass acceleration models

Mass transfer coefficient in disturbed flow due to orifice for flow accelerated corrosion in nuclear power plant

International Nuclear Information System (INIS)

Prasad, Mahendra; Gaikwad, Avinash J.; Sridharan, Arunkumar; Parida, Smrutiranjan

2015-01-01

The flow of fluid in pipes cause corrosion wherein the inner surface of pipe becomes progressively thinner and susceptible to failure. This form of corrosion dependent on flow dynamics is called Flow Accelerated Corrosion (FAC) and has been observed in Nuclear Power Plants (NPPs). Mass transfer coefficient (MTC) is related to extent of wall thinning and it changes from its value in a straight pipe (with same fluid parameters) for flow in orifices, bends, junctions etc. due to gross disturbance of the velocity profile. This paper presents two-dimensional computational fluid dynamics (CFD) simulations for an orifice configuration in a straight pipe. Turbulent model K- ω with shear stress transport and transition flow was the model used for simulation studies. The mass transfer boundary layer (MTBL) thickness δ mtbl is related to the Schmidt number (Sc) and hydrodynamic boundary layer thickness δ h , as δ mtbl ~ δh/(Sc 1/3 ). MTBL is significantly smaller than δ h and hence boundary layer meshing was carried out deep into δ mtbl . Uniform velocity profile was applied at the inlet. Post orifice fluid shows large recirculating flows on the upper and lower wall. At various locations after orifice, mass transfer coefficient is calculated and compared with the value in straight pipe with fully developed turbulent flow. The MTC due to the orifice increases and it is correlated with enhanced FAC in region after orifice. (author)

SU-8 micro Coriolis mass flow sensor

NARCIS (Netherlands)

Monge, Rosa; Groenesteijn, Jarno; Alveringh, Dennis; Wiegerink, Remco J.; Lötters, Joost Conrad; Fernandez, Luis J.

2017-01-01

Abstract This work presents the modelling, design, fabrication and test of the first micro Coriolis mass flow sensor fully fabricated in SU-8 by photolithography processes. The sensor consists of a channel with rectangular cross-section with inner opening of 100 μm × 100 μm and is actuated at

Upwind discontinuous Galerkin methods with mass conservation of both phases for incompressible two-phase flow in porous media

KAUST Repository

Kou, Jisheng

2014-03-22

Discontinuous Galerkin methods with interior penalties and upwind schemes are applied to the original formulation modeling incompressible two-phase flow in porous media with the capillary pressure. The pressure equation is obtained by summing the discretized conservation equations of two phases. This treatment is very different from the conventional approaches, and its great merit is that the mass conservations hold for both phases instead of only one phase in the conventional schemes. By constructing a new continuous map and using the fixed-point theorem, we prove the global existence of discrete solutions under the proper conditions, and furthermore, we obtain a priori hp error estimates of the pressures in L 2 (H 1) and the saturations in L ∞(L 2) and L 2 (H 1). © 2014 Wiley Periodicals, Inc.

Upwind discontinuous Galerkin methods with mass conservation of both phases for incompressible two-phase flow in porous media

KAUST Repository

Kou, Jisheng; Sun, Shuyu

2014-01-01

Discontinuous Galerkin methods with interior penalties and upwind schemes are applied to the original formulation modeling incompressible two-phase flow in porous media with the capillary pressure. The pressure equation is obtained by summing the discretized conservation equations of two phases. This treatment is very different from the conventional approaches, and its great merit is that the mass conservations hold for both phases instead of only one phase in the conventional schemes. By constructing a new continuous map and using the fixed-point theorem, we prove the global existence of discrete solutions under the proper conditions, and furthermore, we obtain a priori hp error estimates of the pressures in L 2 (H 1) and the saturations in L ∞(L 2) and L 2 (H 1). © 2014 Wiley Periodicals, Inc.

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.

A mass-conserving multiphase lattice Boltzmann model for simulation of multiphase flows

Science.gov (United States)

Niu, Xiao-Dong; Li, You; Ma, Yi-Ren; Chen, Mu-Feng; Li, Xiang; Li, Qiao-Zhong

2018-01-01

In this study, a mass-conserving multiphase lattice Boltzmann (LB) model is proposed for simulating the multiphase flows. The proposed model developed in the present study is to improve the model of Shao et al. ["Free-energy-based lattice Boltzmann model for simulation of multiphase flows with density contrast," Phys. Rev. E 89, 033309 (2014)] by introducing a mass correction term in the lattice Boltzmann model for the interface. The model of Shao et al. [(the improved Zheng-Shu-Chew (Z-S-C model)] correctly considers the effect of the local density variation in momentum equation and has an obvious improvement over the Zheng-Shu-Chew (Z-S-C) model ["A lattice Boltzmann model for multiphase flows with large density ratio," J. Comput. Phys. 218(1), 353-371 (2006)] in terms of solution accuracy. However, due to the physical diffusion and numerical dissipation, the total mass of each fluid phase cannot be conserved correctly. To solve this problem, a mass correction term, which is similar to the one proposed by Wang et al. ["A mass-conserved diffuse interface method and its application for incompressible multiphase flows with large density ratio," J. Comput. Phys. 290, 336-351 (2015)], is introduced into the lattice Boltzmann equation for the interface to compensate the mass losses or offset the mass increase. Meanwhile, to implement the wetting boundary condition and the contact angle, a geometric formulation and a local force are incorporated into the present mass-conserving LB model. The proposed model is validated by verifying the Laplace law, simulating both one and two aligned droplets splashing onto a liquid film, droplets standing on an ideal wall, droplets with different wettability splashing onto smooth wax, and bubbles rising under buoyancy. Numerical results show that the proposed model can correctly simulate multiphase flows. It was found that the mass is well-conserved in all cases considered by the model developed in the present study. The developed

Study of hydrodynamic and mass transfer parameters in pulsed sieve-plate columns

International Nuclear Information System (INIS)

Safdari, J.

2001-01-01

One of the most important liquid-liquid extractor in industry is pulsed column. The pulsed columns are generally classified into the following categories: 1-Pulsed perforated-plate column. 2- Pulsed packed column. The pulsed plate column is differential contactor with the application of mechanical energy and is used for a diverse range of processes. Probably its best known application has been in the nuclear fuel industry. The pulsed plate column consists of a cylindrical shell with settling zones at the top and the bottom of the column. The liquids are fed continuously to the column (flowing counter-currently) and are removed continuously from opposite ends of the column. In this work using a pilot pulsed plate column and two different chemical systems (toluene/acetone/water and n-butyl acetate/acetone/water) various experiments are carried out. In each experiment direction of mass transfer is from organic phase (dispersed phase) into aqueous phase (continuous phase) and the continuous phase is water. The main objects of this thesis are as follow: a- Investigation of effect of operating parameters on dispersed phase hold up, volumetric overall mass transfer coefficients based on dispersed and continuous phase, extraction efficiency, pressure drop of column and flooding velocities (maximum column capacities). Obtained results in this part show that if the calorimetric flow rate of aqueous phase or pulsation intensity increase, hold up, volumetric overall mass transfer coefficients based on both two phases and extraction efficiency will increase and flooding velocities will decrease. Also results show that if volumetric flow rate of organic phase increase, hold up, volumetric mass transfer coefficients based on both two phases and pressure drop will increase and extraction efficiency and flooding velocities will decrease. b- Investigation of effect of internal circulation inside drops in designing pulsed perforated-plate column

Generalized derivation of the added-mass and circulatory forces for viscous flows

Science.gov (United States)

Limacher, Eric; Morton, Chris; Wood, David

2018-01-01

The concept of added mass arises from potential flow analysis and is associated with the acceleration of a body in an inviscid irrotational fluid. When shed vorticity is modeled as vortex singularities embedded in this irrotational flow, the associated force can be superimposed onto the added-mass force due to the linearity of the governing Laplace equation. This decomposition of force into added-mass and circulatory components remains common in modern aerodynamic models, but its applicability to viscous separated flows remains unclear. The present work addresses this knowledge gap by presenting a generalized derivation of the added-mass and circulatory force decomposition which is valid for a body of arbitrary shape in an unbounded, incompressible fluid domain, in both two and three dimensions, undergoing arbitrary motions amid continuous distributions of vorticity. From the general expression, the classical added-mass force is rederived for well-known canonical cases and is seen to be additive to the circulatory force for any flow. The formulation is shown to be equivalent to existing theoretical work under the specific conditions and assumptions of previous studies. It is also validated using a numerical simulation of a pitching plate in a steady freestream flow, conducted by Wang and Eldredge [Theor. Comput. Fluid Dyn. 27, 577 (2013), 10.1007/s00162-012-0279-5]. In response to persistent confusion in the literature, a discussion of the most appropriate physical interpretation of added mass is included, informed by inspection of the derived equations. The added-mass force is seen to account for the dynamic effect of near-body vorticity and is not (as is commonly claimed) associated with the acceleration of near-body fluid which "must" somehow move with the body. Various other consequences of the derivation are discussed, including a concept which has been labeled the conservation of image-vorticity impulse.

Factors Affecting Corporate Cash Holding of Non-Financial Firms in Pakistan

Directory of Open Access Journals (Sweden)

Atif Kafayat

2014-06-01

Full Text Available The previous researches explore the question of why firms hold cash. But there are few researches done in developing countries like Pakistan. The need for cash is characterized by its policies of firms regarding capital structure, working capital requirements, cash flow management, dividend payments, and asset management. In this paper, the impact of these factors is normally analyzed under the framework of Tradeoff theory, Pecking Order Theory and Free Cash Flow Theory. This paper focuses on determining the level of corporate cash holdings of non-financial Pakistani firms, and cash holding requirement among different industries. The data is set for period of 2008- 2012 by using the data of 40companies and 6 industries. The findings of the study support the theories. Which show that firm size, net working capital, leverage, Capital Expenditure and Dividend significantly affect the cash holdings of non-financial firms in Pakistan.

The Parent Control in the Mechanical Engineering Management-Holding

Science.gov (United States)

Šnircová, Jana; Hodulíková, Petra; Joehnk, Peter

2012-12-01

The group of entities under the control of parent, so called holding, is arisen as the result and the most often used form of the business concentration nowadays. The paper is focused to find special tasks of parent company for to preserve effective unified economic control in the management-holding. The unified economic control the holding exists in the conditions of the main conflict of interest - holding is not a legal but economic unit and the connected companies into it have a legal autonomy with the economic dependence. The unified economic control limits the financial independence of every individual company of the holding. The attention in the paper is concentrated to the management concept of the parent control, i.e. the parent company supervises the control of intragroup flows and all of subsidiaries production activities.

Remote-controlled stop of phloem mass flow by biphasic occlusion in Cucurbita maxima.

Science.gov (United States)

Furch, Alexandra C U; Zimmermann, Matthias R; Will, Torsten; Hafke, Jens B; van Bel, Aart J E

2010-08-01

The relationships between damage-induced electropotential waves (EPWs), sieve tube occlusion, and stop of mass flow were investigated in intact Cucurbita maxima plants. After burning leaf tips, EPWs propagating along the phloem of the main vein were recorded by extra- and intracellular microelectrodes. The respective EPW profiles (a steep hyperpolarization/depolarization peak followed by a prolonged hyperpolarization/depolarization) probably reflect merged action and variation potentials. A few minutes after passage of the first EPW peak, sieve tubes gradually became occluded by callose, with maximum synthesis occurring approximately 10 min after burning. Early stop of mass flow, well before completion of callose deposition, pointed to an occlusion mechanism preceding callose deposition. This obstruction of mass flow was inferred from the halt of carboxyfluorescein movement in sieve tubes and intensified secretion of aqueous saliva by feeding aphids. The early occlusion is probably due to proteins, as indicated by a dramatic drop in soluble sieve element proteins and a simultaneous coagulation of sieve element proteins shortly after the burning stimulus. Mass flow resumed 30-40 min after burning, as demonstrated by carboxyfluorescein movement and aphid activities. Stop of mass flow by Ca(2+)-dependent occlusion mechanisms is attributed to Ca(2+) influx during EPW passage; the reversibility of the occlusion is explained by removal of Ca(2+) ions.

A simple mass-conserved level set method for simulation of multiphase flows

Science.gov (United States)

Yuan, H.-Z.; Shu, C.; Wang, Y.; Shu, S.

2018-04-01

In this paper, a modified level set method is proposed for simulation of multiphase flows with large density ratio and high Reynolds number. The present method simply introduces a source or sink term into the level set equation to compensate the mass loss or offset the mass increase. The source or sink term is derived analytically by applying the mass conservation principle with the level set equation and the continuity equation of flow field. Since only a source term is introduced, the application of the present method is as simple as the original level set method, but it can guarantee the overall mass conservation. To validate the present method, the vortex flow problem is first considered. The simulation results are compared with those from the original level set method, which demonstrates that the modified level set method has the capability of accurately capturing the interface and keeping the mass conservation. Then, the proposed method is further validated by simulating the Laplace law, the merging of two bubbles, a bubble rising with high density ratio, and Rayleigh-Taylor instability with high Reynolds number. Numerical results show that the mass is a well-conserved by the present method.

Ultrasonic detection of solid phase mass flow ratio of pneumatic conveying fly ash

Science.gov (United States)

Duan, Guang Bin; Pan, Hong Li; Wang, Yong; Liu, Zong Ming

2014-04-01

In this paper, ultrasonic attenuation detection and weight balance are adopted to evaluate the solid mass ratio in this paper. Fly ash is transported on the up extraction fluidization pneumatic conveying workbench. In the ultrasonic test. McClements model and Bouguer-Lambert-Beer law model were applied to formulate the ultrasonic attenuation properties of gas-solid flow, which can give the solid mass ratio. While in the method of weigh balance, the averaged mass addition per second can reveal the solids mass flow ratio. By contrast these two solid phase mass ratio detection methods, we can know, the relative error is less.

Effects of Pulsating Flow on Mass Flow Balance and Surge Margin in Parallel Turbocharged Engines

OpenAIRE

Thomasson, Andreas; Eriksson, Lars

2015-01-01

The paper extends a mean value model of a parallel turbocharged internal combustion engine with a crank angle resolved cylinder model. The result is a 0D engine model that includes the pulsating flow from the intake and exhaust valves. The model captures variations in turbo speed and pressure, and therefore variations in the compressor operating point, during an engine cycle. The model is used to study the effect of the pulsating flow on mass flow balance and surge margin in parallel turbocha...

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.

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

International Nuclear Information System (INIS)

Song Ding; Peng Lihui; Lu Geng; Yang Shiyuan; Yan Yong

2009-01-01

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.

Nuclear assay of coal. Volume 6. Mass flow devices for coal handling. Final report

International Nuclear Information System (INIS)

Gozani, T.; Elias, E.; Bevan, R.

1980-04-01

The mass of coal entering the boiler per unit time is an essential parameter for determining the total rate of heat input. The mass flow rate of coal on a conveyor belt is generally determined as a product of the instantaneous mass of material on a short section of the belt and the belt velocity. Belt loading could be measured by conventional transducers incorporating mechanical or electromechanical weighers or by gamma-ray attenuation gauge. This report reviews the state of the art in mass flow devices for coal handling. The various methods are compared and commented upon. Special design issues are discussed relative to incorporating a mass flow measuring device in a Continuous On-Line Nuclear Analysis of Coal (CONAC) system

Bayesian inference in mass flow simulations - from back calculation to prediction

Science.gov (United States)

Kofler, Andreas; Fischer, Jan-Thomas; Hellweger, Valentin; Huber, Andreas; Mergili, Martin; Pudasaini, Shiva; Fellin, Wolfgang; Oberguggenberger, Michael

2017-04-01

Mass flow simulations are an integral part of hazard assessment. Determining the hazard potential requires a multidisciplinary approach, including different scientific fields such as geomorphology, meteorology, physics, civil engineering and mathematics. An important task in snow avalanche simulation is to predict process intensities (runout, flow velocity and depth, ...). The application of probabilistic methods allows one to develop a comprehensive simulation concept, ranging from back to forward calculation and finally to prediction of mass flow events. In this context optimized parameter sets for the used simulation model or intensities of the modeled mass flow process (e.g. runout distances) are represented by probability distributions. Existing deterministic flow models, in particular with respect to snow avalanche dynamics, contain several parameters (e.g. friction). Some of these parameters are more conceptual than physical and their direct measurement in the field is hardly possible. Hence, parameters have to be optimized by matching simulation results to field observations. This inverse problem can be solved by a Bayesian approach (Markov chain Monte Carlo). The optimization process yields parameter distributions, that can be utilized for probabilistic reconstruction and prediction of avalanche events. Arising challenges include the limited amount of observations, correlations appearing in model parameters or observed avalanche characteristics (e.g. velocity and runout) and the accurate handling of ensemble simulations, always taking into account the related uncertainties. Here we present an operational Bayesian simulation framework with r.avaflow, the open source GIS simulation model for granular avalanches and debris flows.

Calibration of nozzle for air mass flow measurement

Science.gov (United States)

Uher, Jan; Kanta, Lukáš

2017-09-01

The effort to make calibration measurement of mass flow through a nozzle was not satisfying. Traversing across the pipe radius with Pitot probe was done. The presence of overshoot behind the bend in the pipe was found. The overshoot led to an asymmetric velocity profile.

Remote-controlled stop of phloem mass flow by biphasic occlusion in Cucurbita maxima

Science.gov (United States)

Furch, Alexandra C. U.; Zimmermann, Matthias R.; Will, Torsten; Hafke, Jens B.; van Bel, Aart J. E.

2010-01-01

The relationships between damage-induced electropotential waves (EPWs), sieve tube occlusion, and stop of mass flow were investigated in intact Cucurbita maxima plants. After burning leaf tips, EPWs propagating along the phloem of the main vein were recorded by extra- and intracellular microelectrodes. The respective EPW profiles (a steep hyperpolarization/depolarization peak followed by a prolonged hyperpolarization/depolarization) probably reflect merged action and variation potentials. A few minutes after passage of the first EPW peak, sieve tubes gradually became occluded by callose, with maximum synthesis occurring ∼10 min after burning. Early stop of mass flow, well before completion of callose deposition, pointed to an occlusion mechanism preceding callose deposition. This obstruction of mass flow was inferred from the halt of carboxyfluorescein movement in sieve tubes and intensified secretion of aqueous saliva by feeding aphids. The early occlusion is probably due to proteins, as indicated by a dramatic drop in soluble sieve element proteins and a simultaneous coagulation of sieve element proteins shortly after the burning stimulus. Mass flow resumed 30–40 min after burning, as demonstrated by carboxyfluorescein movement and aphid activities. Stop of mass flow by Ca2+-dependent occlusion mechanisms is attributed to Ca2+ influx during EPW passage; the reversibility of the occlusion is explained by removal of Ca2+ ions. PMID:20584788

UF6 Density and Mass Flow Measurements for Enrichment Plants using Acoustic Techniques

Energy Technology Data Exchange (ETDEWEB)

Good, Morris S.; Smith, Leon E.; Warren, Glen A.; Jones, Anthony M.; Ramuhalli, Pradeep; Roy, Surajit; Moran, Traci L.; Denslow, Kayte M.; Longoni, Gianluca

2017-09-01

A key enabling capability for enrichment plant safeguards being considered by the International Atomic Energy Agency (IAEA) is high-accuracy, noninvasive, unattended measurement of UF6 gas density and mass flow rate. Acoustic techniques are currently used to noninvasively monitor gas flow in industrial applications; however, the operating pressures at gaseous centrifuge enrichment plants (GCEPs) are roughly two orders magnitude below the capabilities of commercial instrumentation. Pacific Northwest National Laboratory is refining acoustic techniques for estimating density and mass flow rate of UF6 gas in scenarios typical of GCEPs, with the goal of achieving 1% measurement accuracy. Proof-of-concept laboratory measurements using a surrogate gas for UF6 have demonstrated signatures sensitive to gas density at low operating pressures such as 10–50 Torr, which were observed over the background acoustic interference. Current efforts involve developing a test bed for conducting acoustic measurements on flowing SF6 gas at representative flow rates and pressures to ascertain the viability of conducting gas flow measurements under these conditions. Density and flow measurements will be conducted to support the evaluation. If successful, the approach could enable an unattended, noninvasive approach to measure mass flow in unit header pipes of GCEPs.

Analysis of Cattaneo-Christov heat and mass fluxes in the squeezed flow embedded in porous medium with variable mass diffusivity

Directory of Open Access Journals (Sweden)

M. Farooq

Full Text Available This research article investigates the squeezing flow of Newtonian fluid with variable viscosity over a stretchable sheet inserted in Darcy porous medium. Cattaneo-Christov double diffusion models are implemented to scrutinize the characteristics of heat and mass transfer via variable thermal conductivity and variable mass diffusivity. These models are the modification of conventional laws of Fourier’s and Fick’s via thermal and solutal relaxation times respectively. The homotopy analysis Method (HAM is being utilized to provide the solution of highly nonlinear system of coupled partial differential equations after converted into dimensionless governing equations. The behavior of flow parameters on velocity, concentration, and temperature distributions are sketched and analyzed physically. The result indicates that both concentration and temperature distributions decay for higher solutal and thermal relaxation parameters respectively. Keywords: Squeezing flow, Porous medium, Variable viscosity, Cattaneo-Christov heat and mass flux models, Variable thermal conductivity, Variable mass diffusivity

Heat and mass transfer and hydrodynamics in swirling flows (review)

Science.gov (United States)

Leont'ev, A. I.; Kuzma-Kichta, Yu. A.; Popov, I. A.

2017-02-01

Research results of Russian and foreign scientists of heat and mass transfer in whirling flows, swirling effect, superficial vortex generators, thermodynamics and hydrodynamics at micro- and nanoscales, burning at swirl of the flow, and technologies and apparatuses with the use of whirling currents for industry and power generation were presented and discussed at the "Heat and Mass Transfer in Whirling Currents" 5th International Conference. The choice of rational forms of the equipment flow parts when using whirling and swirling flows to increase efficiency of the heat-power equipment and of flow regimes and burning on the basis of deep study of the flow and heat transfer local parameters was set as the main research prospect. In this regard, there is noticeable progress in research methods of whirling and swirling flows. The number of computational treatments of swirling flows' local parameters has been increased. Development and advancement of the up to date computing models and national productivity software are very important for this process. All experimental works are carried out with up to date research methods of the local thermoshydraulic parameters, which enable one to reveal physical mechanisms of processes: PIV and LIV visualization techniques, high-speed and infrared photography, high speed registration of parameters of high-speed processes, etc. There is a problem of improvement of researchers' professional skills in the field of fluid mechanics to set adequately mathematics and physics problems of aerohydrodynamics for whirling and swirling flows and numerical and pilot investigations. It has been pointed out that issues of improvement of the cooling system and thermal protection effectiveness of heat-power and heat-transfer equipment units are still actual. It can be solved successfully using whirling and swirling flows as simple low power consumption exposing on the flow method and heat transfer augmentation.

Optimization of mass flow rate in RGTT200K coolant purification for Carbon Monoxide conversion process

International Nuclear Information System (INIS)

Sumijanto; Sriyono

2016-01-01

Carbon monoxide is a species that is difficult to be separated from the reactor coolant helium because it has a relatively small molecular size. So it needs a process of conversion from carbon monoxide to carbondioxide. The rate of conversion of carbon monoxide in the purification system is influenced by several parameters including concentration, temperature and mass flow rate. In this research, optimization of the mass flow rate in coolant purification of RGTT200K for carbon monoxide conversion process was done. Optimization is carried out by using software Super Pro Designer. The rate of reduction of reactant species, the growth rate between the species and the species products in the conversion reactions equilibrium were analyzed to derive the mass flow rate optimization of purification for carbon monoxide conversion process. The purpose of this study is to find the mass flow rate of purification for the preparation of the basic design of the RGTT200K coolant helium purification system. The analysis showed that the helium mass flow rate of 0.6 kg/second resulted in an un optimal conversion process. The optimal conversion process was reached at a mass flow rate of 1.2 kg/second. A flow rate of 3.6 kg/second – 12 kg/second resulted in an ineffective process. For supporting the basic design of the RGTT200K helium purification system, the mass flow rate for carbon monoxide conversion process is suggested to be 1.2 kg/second. (author)

Modeling, design, fabrication and characterization of a micro Coriolis mass flow sensor

International Nuclear Information System (INIS)

Haneveld, J; Lammerink, T S J; De Boer, M J; Sanders, R G P; Mehendale, A; Lötters, J C; Dijkstra, M; Wiegerink, R J

2010-01-01

This paper discusses the modeling, design and realization of micromachined Coriolis mass flow sensors. A lumped element model is used to analyze and predict the sensor performance. The model is used to design a sensor for a flow range of 0–1.2 g h −1 with a maximum pressure drop of 1 bar. The sensor was realized using semi-circular channels just beneath the surface of a silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. Special comb-shaped electrodes are integrated on the channels for capacitive readout of the extremely small Coriolis displacements. The comb-shaped electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods. Furthermore, it prevents squeezed film damping due to a thin layer of air between the capacitor electrodes. As a result, the sensor operates at atmospheric pressure with a quality factor in the order of 40 and does not require vacuum packaging like other micro Coriolis flow sensors. Measurement results using water, ethanol, white gas and argon are presented, showing that the sensor measures true mass flow. The measurement error is currently in the order of 1% of the full scale of 1.2 g h −1

Hydromagnetic nonlinear thermally radiative nanoliquid flow with Newtonian heat and mass conditions

Directory of Open Access Journals (Sweden)

Muhammad Ijaz Khan

Full Text Available This paper communicates the analysis of MHD three-dimensional flow of Jeffrey nanoliquid over a stretchable surface. Flow due to a bidirectional surface is considered. Heat and mass transfer subject to volume fraction of nanoparticles, heat generation and nonlinear solar radiation are examined. Newtonian heat and mass transportation conditions are employed at surface. Concept of boundary layer is utilized to developed the mathematical problem. The boundary value problem is dictated by ten physical parameters: Deborah number, Hartman number, ratio of stretching rates, thermophoretic parameter, Brownian motion parameter, Prandtl number, temperature ratio parameter, conjugate heat and mass parameters and Lewis number. Convergent solutions are obtained using homotopic procedure. Convergence zone for obtained results is explicitly identified. The obtained solutions are interpreted physically. Keywords: Hydromagnetic flow, Viscoelastic nanofluid, Thermophoretic and Brownian moment, Nonlinear thermal radiation, Heat generation

Post Analysis of Two Phase Natural Circulation Mass Flow Rate for CE-PECS

Energy Technology Data Exchange (ETDEWEB)

Park, R. J.; Ha, K. S.; Rhee, B. W.; Kim, H. Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The coolant in the inclined channel absorbs the decay heat and sensible heat transferred from the corium through the structure of the core catcher body and flows up to the pool as a two phase mixture. On the other hand, some of the pool water will flow into the inlet of the downcomer piping, and will flow into the inclined cooling channel of the core catcher by gravity. The engineered cooling channel is designed to provide effective long-term cooling and stabilization of the corium mixture in the core catcher body while facilitating steam venting. To maintain the integrity of the ex-vessel core catcher, however, it is required that the coolant be circulated at a rate along the inclined cooling channel sufficient to avoid CHF (Critical Heat Flux) on the heating surface of the cooling channel. In this study, post simulations of two phase natural circulation in the CEPECS have been performed to evaluate two phase flow characteristics and the natural circulation mass flow rate in the flow channel using the RELAP5/MOD3 computer code. Post simulations of two phase natural circulation in the CE-PECS have been conducted to evaluate two phase flow characteristics and the natural circulation mass flow rate in the flow channel using the RELAP5/MOD3 computer code. The RELAP5/MOD3 results have shown that the water circulation mass flow rate is approximately 8.7 kg/s in the base case.

Post Analysis of Two Phase Natural Circulation Mass Flow Rate for CE-PECS

International Nuclear Information System (INIS)

Park, R. J.; Ha, K. S.; Rhee, B. W.; Kim, H. Y.

2015-01-01

The coolant in the inclined channel absorbs the decay heat and sensible heat transferred from the corium through the structure of the core catcher body and flows up to the pool as a two phase mixture. On the other hand, some of the pool water will flow into the inlet of the downcomer piping, and will flow into the inclined cooling channel of the core catcher by gravity. The engineered cooling channel is designed to provide effective long-term cooling and stabilization of the corium mixture in the core catcher body while facilitating steam venting. To maintain the integrity of the ex-vessel core catcher, however, it is required that the coolant be circulated at a rate along the inclined cooling channel sufficient to avoid CHF (Critical Heat Flux) on the heating surface of the cooling channel. In this study, post simulations of two phase natural circulation in the CEPECS have been performed to evaluate two phase flow characteristics and the natural circulation mass flow rate in the flow channel using the RELAP5/MOD3 computer code. Post simulations of two phase natural circulation in the CE-PECS have been conducted to evaluate two phase flow characteristics and the natural circulation mass flow rate in the flow channel using the RELAP5/MOD3 computer code. The RELAP5/MOD3 results have shown that the water circulation mass flow rate is approximately 8.7 kg/s in the base case

Mass Flow Data Comparison for Comprehensive Fuel Cycle Options

International Nuclear Information System (INIS)

Kim, T.K.; Taiwo, T.A.; Wigeland, R.A.; Dixon, B.W.; Gehin, J.C.; Todosow, M.

2015-01-01

One of the key objectives stated in the United States Department of Energy, Nuclear Energy R and D road-map is the development of sustainable nuclear fuel cycles that improve natural resource utilisation and provide adequate capability and capacity to manage wastes produced by the fuel cycle. In order to inform this objective, an evaluation and screening of nuclear fuel cycle options has been conducted. As part of that effort, the entire fuel cycle options space was represented by 40 Evaluation Groups (EGs), and mass flow information for each of the EGs was provided by using an Analysis Example (AE). In this paper, the mass flow data of the 40 AEs are compared to inform on trends in the natural resource utilisation and nuclear waste generation. For the AEs that need enriched uranium support, the natural uranium required is high and the natural resource utilisation is generally lower than 2% regardless of the fuel cycle strategy (i.e., once-through, limited recycle, or continuous recycle). However, the utilisation could be improved by avoiding enriched uranium fuel support. The natural resource utilisation increases to more than 80% by recycling the nuclear fuel continuously without enriched uranium support. The combined mass of spent nuclear fuel (SNF) and high-level waste (HLW), i.e., SNF+HLW mass, is lower by using a continuous recycle option compared to a once-through fuel cycle option, because SNF mass is converted to mass of recycled products and only fission products and other process losses need to be disposed. The combined disposed mass of depleted uranium (DU), recovered uranium (RU) and thorium (RTh), i.e. DU+RU+RTh mass, has a similar trend to the uranium utilisation. For the AEs that need enriched uranium fuel, the DU and RU are the major fraction by mass of the DU+RU+RTh, which are two orders of magnitude higher in mass compared to those for the AEs that do not need enriched uranium fuel. (authors)

The Role of Cash Holdings in Reducing Investment-Cash Flow Sensitivity: Evidence from a Financial Crisis Period in an Emerging Market

OpenAIRE

Ozgur Arslan; Chrisostomos Florackis; Aydin Ozkan

2006-01-01

This paper investigates the relationship between financing constraints and investment-cash flow sensitivities by focusing on cash holdings of firms as the basic classification scheme to separate firms into financially constrained and unconstrained categories. The idea is that high cash reserves increase the ability of firms to undertake profitable investment opportunities. Our classification scheme is based on an optimal cash model, which helps us identify the firms that deviate significantly...

Operating range, hold-up, droplet size and axial mixing of pulsed plate columns in highly disperse and low-continuity volume flows

International Nuclear Information System (INIS)

Schmidt, H.; Miller, H.

Operating behavior, hold-up, droplet size and axial mixing are investigated in highly disperse and slightly continuous volume flows in a pulsed plate column. The geometry of the column of 4-m length and 10-cm inside diameter was held constant. The hole shape of the column bases was changed, wherby the cylindrical, sharp-edge drilled hole is compared with the punched, nozzle-shaped hole in their effects on the fluid-dynamic behavior. In this case we varied the volume flows, the ratio of volume flows, the pulse frequency and the operating temperature. The operation was held constant for the aqueous, the organic, the continuous and the disperse phases. The objective was to demonstrate the applicability of pulsed plate columns with very large differences between the organic disperse and the aqueous continuous volume flow, to obtain design data for such columns and to perform a scale-up to industrial reprocessing plant-size. 18 references, 11 figures, 3 tables

Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

OpenAIRE

Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

2016-01-01

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip bounda...

Method and apparatus for simultaneous determination of fluid mass flow rate, mean velocity and density

International Nuclear Information System (INIS)

Hamel, W.R.

1984-01-01

This invention relates to a new method and new apparatus for determining fluid mass flow rate and density. In one aspect of the invention, the fluid is passed through a straight cantilevered tube in which transient oscillation has been induced, thus generating Coriolis damping forces on the tube. The decay rate and frequency of the resulting damped oscillation are measured, and the fluid mass flow rate and density are determined therefrom. In another aspect of the invention, the fluid is passed through the cantilevered tube while an electrically powered device imparts steady-state harmonic excitation to the tube. This generates Coriolis tube-damping forces which are dependent on the mass flow rate of the fluid. Means are provided to respond to incipient flow-induced changes in the amplitude of vibration by changing the power input to the excitation device as required to sustain the original amplitude of vibration. The fluid mass flow rate and density are determined from the required change in power input. The invention provides stable, rapid, and accurate measurements. It does not require bending of the fluid flow

Prediction of Mass Flow Rate in Supersonic Natural Gas Processing

Directory of Open Access Journals (Sweden)

Wen Chuang

2015-11-01

Full Text Available The mass flow rate of natural gas through the supersonic separator was numerically calculated by various cubic equations of state. The numerical results show that the compressibility factor and specific heat ratio for ideal gas law diverge remarkably from real gas models at a high inlet pressure. Simultaneously, the deviation of mass flow calculated by the ideal and real gas models reaches over 10 %. The difference increases with the lower of the inlet temperature regardless of the inlet pressure. A higher back pressure results in an earlier location of the shock wave. The pressure ratio of 0.72 is the first threshold to get the separator work normally. The second threshold is 0.95, in which case the whole flow is subsonic and cannot reach the choked state. The shock position moves upstream with the real gas model compared to the ideal gas law in the cyclonic separation section.

Detailed evaluation of the natural circulation mass flow rate of water propelled by using an air injection

International Nuclear Information System (INIS)

Park, Rae-Joon; Ha, Kwang-Soon; Kim, Jae-Cheol; Hong, Seong-Wan; Kim, Sang-Baik

2008-01-01

One-dimensional (1D) air-water two-phase natural circulation flow in the thermohydraulic evaluation of reactor cooling mechanism by external self-induced flow - one-dimensional' (THERMES-1D) experiment has been verified and evaluated by using the RELAP5/MOD3 computer code. Experimental results on the 1D natural circulation mass flow rate of water propelled by using an air injection have been evaluated in detail. The RELAP5 results have shown that an increase in the air injection rate to 50% of the total heat flux leads to an increase in the water circulation mass flow rate. However, an increase in the air injection rate from 50 to 100% does not affect the water circulation mass flow rate, because of the inlet area condition. As the height increases in the air injection part, the void fraction increases. However, the void fraction in the upper part of the air injector maintains a constant value. An increase in the air injection mass flow rate leads to an increase in the local void fraction, but it has no influence on the local pressure. An increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area does not have an influence on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases. (author)

Modelling of convective heat and mass transfer in rotating flows

CERN Document Server

Shevchuk, Igor V

2016-01-01

 This monograph presents results of the analytical and numerical modeling of convective heat and mass transfer in different rotating flows caused by (i) system rotation, (ii) swirl flows due to swirl generators, and (iii) surface curvature in turns and bends. Volume forces (i.e. centrifugal and Coriolis forces), which influence the flow pattern, emerge in all of these rotating flows. The main part of this work deals with rotating flows caused by system rotation, which includes several rotating-disk configurations and straight pipes rotating about a parallel axis. Swirl flows are studied in some of the configurations mentioned above. Curvilinear flows are investigated in different geometries of two-pass ribbed and smooth channels with 180° bends. The author demonstrates that the complex phenomena of fluid flow and convective heat transfer in rotating flows can be successfully simulated using not only the universal CFD methodology, but in certain cases by means of the integral methods, self-similar and analyt...

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Development of a pressure based vortex-shedding meter: measuring unsteady mass-flow in variable density gases

International Nuclear Information System (INIS)

Ford, C L; Winroth, M; Alfredsson, P H

2016-01-01

An entirely pressure-based vortex-shedding meter has been designed for use in practical time-dependent flows. The meter is capable of measuring mass-flow rate in variable density gases in spite of the fact that fluid temperature is not directly measured. Unlike other vortex meters, a pressure based meter is incredibly robust and may be used in industrial type flows; an environment wholly unsuitable for hot-wires for example. The meter has been tested in a number of static and dynamic flow cases, across a range of mass-flow rates and pressures. The accuracy of the meter is typically better than about 3% in a static flow and resolves the fluctuating mass-flow with an accuracy that is better than or equivalent to a hot-wire method. (paper)

The nuclear flow and the mass number dependence of the balance point

International Nuclear Information System (INIS)

Sebille, F.; de la Mota, V.; Remaud, B.; Schuck, P.

1990-01-01

The nuclear flow is studied theoretically with the Landau Vlasov equation in the E/A = 50 to 150 MeV energy domain using the finite range Gogny force. For comparison also other equations of states based on velocity independent mean fields are used. In this paper the mass number dependence of the balance point is investigated. A sensitivity of the flow on the equation of state as a function of mass and energies around and above the balance point can tentatively be advanced

Effect of Reynolds number on flow and mass transfer characteristics of a 90 degree elbow

Science.gov (United States)

Fujisawa, Nobuyuki; Ikarashi, Yuya; Yamagata, Takayuki; Taguchi, Syoichi

2016-11-01

The flow and mass transfer characteristics of a 90 degree elbow was studied experimentally by using the mass transfer measurement by plaster dissolution method, the surface flow visualization by oil film method and stereo PIV measurement. The experiments are carried out in a water tunnel of a circular pipe of 56mm in diameter with a working fluid of water. The Reynolds number was varied from 30000 to 200000. The experimental result indicated the change of the mass transfer coefficient distribution in the elbow with increasing the Reynolds number. This phenomenon is further examined by the surface flow visualization and measurement of secondary flow pattern in the elbow, and the results showed the suggested change of the secondary flow pattern in the elbow with increasing the Reynolds numbers.

Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics (2), flow dynamics calculations for determining mixing factors and mass transfer coefficients

International Nuclear Information System (INIS)

Uehara, Yasushi; Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Koshizuka, Seiichi

2009-01-01

In order to predict and mitigate flow accelerated corrosion (FAC) of carbon steel piping in PWR and BWR secondary systems, computer program packages for evaluating FAC have been developed by coupling one through three dimensional (1-3D) computational flow dynamics (CFD) models and corrosion models. To evaluate corrosive conditions, e.g., oxygen concentration and electrochemical corrosion potential (ECP) along the flow path, flow pattern and temperature in each elemental volume were obtained with 1D computational flow dynamics (CFD) codes. Precise flow turbulence and mass transfer coefficients at the structure surface were calculated with 3D CFD codes to determine wall thinning rates. One of the engineering options is application of k-ε calculation as a 3D CFD code, which has limitation of detail evaluation of flow distribution at very surface of large scale piping. A combination of k-ε calculation and wall function was proposed to evaluate precise distribution of mass transfer coefficients with reasonable CPU volume and computing time and, at the same time, reasonable accuracy. (author)

Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow

Energy Technology Data Exchange (ETDEWEB)

Kang, Chang Woo; Yang, Kyung Soo [Inha University, Incheon (Korea, Republic of)

2014-12-15

Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re{sub r} = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in

Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow

International Nuclear Information System (INIS)

Kang, Chang Woo; Yang, Kyung Soo

2014-01-01

Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re r = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in the

DECSERVIS-2: A tool for natural decay series mass flow simulation

International Nuclear Information System (INIS)

Azzam, Saad; Suksi, Juhani; Ammann, Michael

2009-01-01

After the publication of 'DECSERVIS: a tool for radioactive decay series visualisation' we have further developed our DECSERVIS software. With the new tool DECSERVIS-2 one can simulate radioactive decay chains in open systems, i.e. when the concentrations of nuclides change also due to mass flows. Decay chains can be simulated under continuous and successive nuclide mass flow events into and out from the system and in freely determined time intervals. Simulation output for the entire decay chain (nuclide activity, mass, number of nuclides, nuclide ratios) can be presented as a function of time with various graphical presentations such as solid curve and column diagrams or animation. In this paper we introduce DECSERVIS-2 and demonstrate its use with simulation examples. DECSERVIS-2 is easy to use and has been designed with an eye on the demands of teaching.

DETERMINANTS AND OPTIMAL LEVEL OF CORPORATE CASH HOLDINGS: EVIDENCE FROM US, UK AND JAPAN

OpenAIRE

Zhang, Shan Shan

2013-01-01

This paper firstly investigates the empirical determinants of corporate cash holdings for a sample of listed US, UK and Japanese firms during the 2000-2012 period. Through applying the pooled time-series cross-sectional estimations, cross-sectional estimations and GMM two-step method of estimations, the results reveal that firms’ cash flow, cash flow variability, bank debt and degree of shareholders protection and creditor protection all have inverse relationship with cash holdings. Contraril...

Implementation of the Fissile Mass Flow Monitor Source Verification and Confirmation

Energy Technology Data Exchange (ETDEWEB)

Uckan, Taner [ORNL; March-Leuba, Jose A [ORNL; Powell, Danny H [ORNL; Nelson, Dennis [Sandia National Laboratories (SNL); Radev, Radoslav [Lawrence Livermore National Laboratory (LLNL)

2007-12-01

This report presents the verification procedure for neutron sources installed in U.S. Department of Energy equipment used to measure fissile material flow. The Fissile Mass Flow Monitor (FMFM) equipment determines the {sup 235}U fissile mass flow of UF{sub 6} gas streams by using {sup 252}Cf neutron sources for fission activation of the UF{sub 6} gas and by measuring the fission products in the flow. The {sup 252}Cf sources in each FMFM are typically replaced every 2 to 3 years due to their relatively short half-life ({approx} 2.65 years). During installation of the new FMFM sources, the source identity and neutronic characteristics provided by the manufacturer are verified with the following equipment: (1) a remote-control video television (RCTV) camera monitoring system is used to confirm the source identity, and (2) a neutron detection system (NDS) is used for source-strength confirmation. Use of the RCTV and NDS permits remote monitoring of the source replacement process and eliminates unnecessary radiation exposure. The RCTV, NDS, and the confirmation process are described in detail in this report.

Implementation of the Fissile Mass Flow Monitor Source Verification and Confirmation

International Nuclear Information System (INIS)

Uckan, Taner; March-Leuba, Jose A.; Powell, Danny H.; Nelson, Dennis; Radev, Radoslav

2007-01-01

This report presents the verification procedure for neutron sources installed in U.S. Department of Energy equipment used to measure fissile material flow. The Fissile Mass Flow Monitor (FMFM) equipment determines the 235 U fissile mass flow of UF 6 gas streams by using 252 Cf neutron sources for fission activation of the UF 6 gas and by measuring the fission products in the flow. The 252 Cf sources in each FMFM are typically replaced every 2 to 3 years due to their relatively short half-life (∼ 2.65 years). During installation of the new FMFM sources, the source identity and neutronic characteristics provided by the manufacturer are verified with the following equipment: (1) a remote-control video television (RCTV) camera monitoring system is used to confirm the source identity, and (2) a neutron detection system (NDS) is used for source-strength confirmation. Use of the RCTV and NDS permits remote monitoring of the source replacement process and eliminates unnecessary radiation exposure. The RCTV, NDS, and the confirmation process are described in detail in this report.

Anatomy and function relation in the coronary tree: from bifurcations to myocardial flow and mass.

Science.gov (United States)

Kassab, Ghassan S; Finet, Gerard

2015-01-01

The study of the structure-function relation of coronary bifurcations is necessary not only to understand the design of the vasculature but also to use this understanding to restore structure and hence function. The objective of this review is to provide quantitative relations between bifurcation anatomy or geometry, flow distribution in the bifurcation and degree of perfused myocardial mass in order to establish practical rules to guide optimal treatment of bifurcations including side branches (SB). We use the scaling law between flow and diameter, conservation of mass and the scaling law between myocardial mass and diameter to provide geometric relations between the segment diameters of a bifurcation, flow fraction distribution in the SB, and the percentage of myocardial mass perfused by the SB. We demonstrate that the assessment of the functional significance of an SB for intervention should not only be based on the diameter of the SB but also on the diameter of the mother vessel as well as the diameter of the proximal main artery, as these dictate the flow fraction distribution and perfused myocardial mass, respectively. The geometric and flow rules for a bifurcation are extended to a trifurcation to ensure optimal therapy scaling rules for any branching pattern.

Where is The Dark Matter: The Flow-field From 2MASS

Science.gov (United States)

Crook, Aidan; Huchra, J.; Macri, L.; Masters, K.; Jarrett, T.

2009-01-01

We present a map of the flow-field constructed from groups of galaxies in the 2MASS Redshift Survey. Previous efforts have suffered because the underlying surveys either did not penetrate to low galactic latitudes or were not sensitive to elliptical galaxies, thereby missing a significant fraction of the mass. The 2MASS Redshift Survey provides a uniform all-sky magnitude-limited sample in the J, H and Ks bands, 97% complete to Ks10°, sensitive to both ellipticals and spirals. We demonstrate how utilizing the properties of galaxy groups leads to improved predictions of peculiar velocities in the nearby Universe, and use dynamical mass estimates to construct a reliable flow-field to 12,000 km/s. We demonstrate its effectiveness in providing distance estimates, and discuss the advantages of this model over earlier work. With independent knowledge of the peculiar velocity of the Local Group, we discuss the implications for the matter density parameter and bias. This work is supported by a Whiteman Fellowship and NSF grant AST-0406906.

Mass spectrometric studies of bimolecular reactions in a selected ion flow tube (SIFT)

International Nuclear Information System (INIS)

Shul, R.J.; Upschulte, B.L.; Passarella, R.; Keesee, R.G.; Castleman, A.W.

1985-01-01

The rate coefficients for a number of thermal energy charge transfer reactions have been obtained with a selected ion flow tube (SIFT). The reactions studied involve Ar + and Ar 2 + with a variety of neutral molecules including: O 2 , CS 2 , CO 2 , SO 2 , H 2 S, NH 3 , and SF 6 . Such reactions have been of long-standing interest in the field of gas-phase ion-molecule chemistry from both a practical and fundamental point of view. Consideration of charge transfer reactions as possible sources of chemical lasers and their role in ionospheric and interstellar chemistry account for much of the interest. Fundamentally, the mechanism involved in these reactions has yet to be definitively established. The consumption deposition of energy into internal modes and translational degrees of freedom in such reactions has also been a topic of considerable debate. The apparatus consists of five main components: an ion source, SIFT quadrupole, ion injector, flow tube, and a mass spectrometer detection system. Ions formed in a high pressure source leak into a SIFT quadrupole where they are mass selected. The primary ion of interest is then injected into the flow tube where reactions are studied. Once in the flow tube the ions are carried downstream by an inert buffer gas, either argon, nitrogen, or helium in the present study. Neutral reactant gas is added through a reactant gas inlet (RGI) at an appropriate location downstream in the flow tube, and allowed to react with the injected ions. Ions on the flow tube axis are sampled through a 1 mm orifice where they are mass analyzed by a second quadrupole mass spectrometer and detected with a channeltron electron multiplier

Mass flows and angular momentum density for px + ipy paired fermions in a harmonic trap

International Nuclear Information System (INIS)

Stone, Michael; Anduaga, Inaki

2008-01-01

We present a simple two-dimensional model of a p x + ip y superfluid in which the mass flow that gives rise to the intrinsic angular momentum is easily calculated by numerical diagonalization of the Bogoliubov-de Gennes operator. We find that, at zero temperature and for constant director l, the mass flow closely follows the Ishikawa-Mermin-Muzikar formula j mass =1/2 curl/(ρhl/2)

Heat and mass transfer in turbulent chemically nonequilibrium flow in the tube with boundary second kind conditions. The section with the stabilized heat and mass transfer

International Nuclear Information System (INIS)

Kritsuk, E.L.; Mishina, L.V.; Shegidevich, L.N.

1986-01-01

The hydrodynamically stabilized chemically nonequilibrium turbulent flow in a tube with the inert impermeable surface and constant specific heat flow on the wall is considered. The reversible homogeneous reaction of nitrogen dioxide dissociation 2NO 2 ↔ 2NO+O 2 takes place in the flow. Chemically equilibrium flow with homogeneous profile of temperature and concentration arrives into the channel inlet. After application of simplifying assumptions, the expressions for characteristics of heat and mass transfer have been written down, which are valid in the whole range of the flow parameter variation from frozen up to chemically equilibrium flow. An integral transformation method is suggested for a radial coordinate which allows a wall region to be extended, thereby essentially extending the step of integration. A solution in quadratures has been obtained for the heat and mass transfer problem in an inert fluid flow for the developed process section. The elimination method has been employed to solve the boundary-value second-kind problem for the function governing heat and mass transfer in a chemically nonequilibrium turbulent flow over the developed heat and mass transfer section. The results of calculations are presented

Device for accurately measuring mass flow of gases

Science.gov (United States)

Hylton, James O.; Remenyik, Carl J.

1994-01-01

A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel.

Breath-hold duration in man and the diving response induced by face immersion.

Science.gov (United States)

Sterba, J A; Lundgren, C E

1988-09-01

The objective of this study in 5 selected volunteer subjects was to see whether the circulatory diving response which is elicited by breath holding and by cold water on the face would affect the duration of maximal-effort breath holds. Compared to control measurements (breath holding during resting, breathing with 35 degrees C water on the face) breath holding with the face cooled by 20 degrees C water caused a 12% reduction of heart rate, 6% reduction of cardiac output, 33% reduction in [corrected] forearm blood flow, and 9% rise in mean arterial blood pressure, but there was no difference in breath-hold duration (control and experimental both 94 s). There were also no differences in time of appearance of the first involuntary respiratory efforts during breath holding, in alveolar gas exchange, or in breaking-point alveolar O2 and CO2 tensions. When the diving response was magnified by a brief bout of exercise so that there was a 19% [corrected] reduction in heart rate, 23% reduction in cardiac output, and 48% reduction in forearm blood flow, breath-hold duration was still unaffected by face cooling. Compared to intermittent immersions, continuous exposure of the face to cold water abolished the diving response, probably by a cold adaptation of facial thermal receptors. These results with cooling of the face only are consistent with our earlier finding that there was a negative correlation between the duration of a maximal-effort breath hold and the diving response during whole-body submersion in cold water.

Reactor mass flow data base prepared for the nonproliferation alternative systems assessment program

International Nuclear Information System (INIS)

Primm III, R.T.C.

1981-02-01

This report presents charge and discharge mass flow data for reactors judged to have received sufficient technical development to enable them to be demonstrated or commercially available by the year 2000. Brief descriptions of the reactors and fuel cycles evaluated are presented. A discussion of the neutronics methods used to produce the mass flow data is provided. Detailed charge and discharge fuel isotopics are presented. U 3 O 8 , separative work, and fissile material requirements are computed and provided for each fuel cycle

Mass transfer from smooth alabaster surfaces in turbulent flows

Science.gov (United States)

Opdyke, Bradley N.; Gust, Giselher; Ledwell, James R.

1987-11-01

The mass transfer velocity for alabaster plates in smooth-wall turbulent flow is found to vary with the friction velocity according to an analytic solution of the advective diffusion equation. Deployment of alabaster plates on the sea floor can perhaps be used to estimate the viscous stress, and transfer velocities for other species.

Optical measurement of a micro coriolis mass flow sensor

NARCIS (Netherlands)

Kristiansen, L.; Mehendale, A.; Brouwer, Dannis Michel; Zwikker, J.M.; Klein, M.E.

2009-01-01

Haneveld [1,2] demonstrated a micro Coriolis mass flow sensor, operating in the measurement range of 0 to 1 g/hr achieving a resolution in the order of 10 mg/hr using a laser vibrometer. Equipped with an integrated capacitive [3] readout the measurement uncertainty amounted to 2% of the full scale

Impact of Heat and Mass Transfer on MHD Oscillatory Flow of Jeffery ...

African Journals Online (AJOL)

The objective of this paper is to study Dufour, Soret and thermal conductivity on unsteady heat and mass transfer of magneto hydrodynamic (MHD) oscillatory flow of Jeffery fluid through a porous medium in a channel. The partial differential equations governing the flow have been solved numerically using semi-implicit ...

Effect of PEEP, blood volume, and inspiratory hold maneuvers on venous return.

Science.gov (United States)

Berger, David; Moller, Per W; Weber, Alberto; Bloch, Andreas; Bloechlinger, Stefan; Haenggi, Matthias; Sondergaard, Soren; Jakob, Stephan M; Magder, Sheldon; Takala, Jukka

2016-09-01

According to Guyton's model of circulation, mean systemic filling pressure (MSFP), right atrial pressure (RAP), and resistance to venous return (RVR) determine venous return. MSFP has been estimated from inspiratory hold-induced changes in RAP and blood flow. We studied the effect of positive end-expiratory pressure (PEEP) and blood volume on venous return and MSFP in pigs. MSFP was measured by balloon occlusion of the right atrium (MSFPRAO), and the MSFP obtained via extrapolation of pressure-flow relationships with airway occlusion (MSFPinsp_hold) was extrapolated from RAP/pulmonary artery flow (QPA) relationships during inspiratory holds at PEEP 5 and 10 cmH2O, after bleeding, and in hypervolemia. MSFPRAO increased with PEEP [PEEP 5, 12.9 (SD 2.5) mmHg; PEEP 10, 14.0 (SD 2.6) mmHg, P = 0.002] without change in QPA [2.75 (SD 0.43) vs. 2.56 (SD 0.45) l/min, P = 0.094]. MSFPRAO decreased after bleeding and increased in hypervolemia [10.8 (SD 2.2) and 16.4 (SD 3.0) mmHg, respectively, P waterfall. Copyright © 2016 the American Physiological Society.

OFFSHORIZATION AS MAIN PROBLEM OF HOLDING GROUPS TAXATION

Directory of Open Access Journals (Sweden)

Y. Petlenko

2016-01-01

Full Text Available At this article, we have analyzed and systematized the conditions of holdings' activity to reduce the taxation level in countries and on the territory of special, so-called offshore, jurisdiction. In addition, we have made a suggestionhow to regulatean offshore capital flows inorder to prevent from tax frauds.

Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

International Nuclear Information System (INIS)

Papell, S.S.; Nyland, T.W.; Saiyed, N.H.

1992-07-01

Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomson devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1-X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band. 3 refs

Detector and front-end electronics of a fissile mass flow monitoring system

International Nuclear Information System (INIS)

Paulus, M.J.; Uckan, T.; Lenarduzzi, R.; Mullens, J.A.; Castleberry, K.N.; McMillan, D.E.; Mihalczo, J.T.

1997-01-01

A detector and front-end electronics unit with secure data transmission has been designed and implemented for a fissile mass flow monitoring system for fissile mass flow of gases and liquids in a pipe. The unit consists of 4 bismuth germanate (BGO) scintillation detectors, pulse-shaping and counting electronics, local temperature sensors, and on-board local area network nodes which locally acquire data and report to the master computer via a secure network link. The signal gain of the pulse-shaping circuitry and energy windows of the pulse-counting circuitry are periodicially self calibrated and self adjusted in situ using a characteristic line in the fissile material pulse height spectrum as a reference point to compensate for drift such as in the detector gain due to PM tube aging. The temperature- dependent signal amplitude variations due to the intrinsic temperature coefficients of the PM tube gain and BGO scintillation efficiency have been characterized and real-time gain corrections introduced. The detector and electronics design, measured intrinsic performance of the detectors and electronics, and the performance of the detector and electronics within the fissile mass flow monitoring system are described

Mass transfer during sulfuric acid concentration by evaporation into the air flow

Directory of Open Access Journals (Sweden)

V. K. Lukashov

2016-12-01

Full Text Available This article shows the results of the study of mass transfer under periodic concentration of sulfuric acid by evaporation inthe gas flow, neutral with respect to the components of acid.Used mathematical model for mass transferbases on the proposed simplified physical representations.This model has allowed to construct an algorithm for calculation the coefficient of mass transfer from the liquid phase into the gas flow. The algorithm uses the experimental data of change the amount of acid and concentration of the water taken from the laboratory tests. Time-based Nusselt diffusion criterion represent the results of the study at different modes of the evaporation process.It has been found that the character of the influence of temperature and initial acid concentration on Nusselt diffusion criterion depends on the variation range of the mass fraction of water in the acid.It is shown that these dependences are well approximated by an exponential function from the dimensionless parameters of the process. This allows usingthem for calculation the mass transfer coefficient into the gas phase in a batch process of concentrating in the range of investigated modes.

Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study

Science.gov (United States)

Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang

2018-01-01

A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.

One-dimensional model of steady, compressible channel flow with mass, momentum, and energy addition

International Nuclear Information System (INIS)

Johnston, S.C.

1976-09-01

A one-dimensional model of steady, compressible channel flow with mass, momentum and energy addition is discussed. An exact solution to the governing equations was found and from it a similarity parameter relating dimensionless mass, momentum and energy addition identified. This similarity parameter is used to make two flows having different dimensionless mass, momentum and energy additions equivalent. Application of the similarity parameter to the LASL Intense Neutron Source experiment and the Sandia simulation of that experiment results in an expression relating the dimensionless mass addition of combustible gas required in the Sandia experiment to dimensionless energy addition in the LASL experiment. Results of the analysis indicate that the Sandia experiment can realistically simulate the energy addition in the LASL Intense Neutron Source experiment

Study on flow and mass transport through fractured sedimentary rocks (2)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Karasaki, Kenzi; Sato, Hisashi; Sawada, Atsushi

2009-03-01

It is important for safety assessment of HLW geological disposal to understand hydro-geological conditions at the investigation area, and to evaluate groundwater flow and mass transport model and parameters, at each investigation phase. Traditionally, for Neogene sedimentary rock, the grain spacing of sediments has been considered as the dominant migration path. However, fractures of sedimentary rock could act as dominant paths, although they were soft sedimentary rocks. In this study, as part of developing groundwater flow and mass transport evaluation methodologies of such a fractured sedimentary rock' distributed area, we conducted two different scale of studies; 1) core rock sample scale and 2) several kilometer scale. For the core rock sample scale, some of laboratory hydraulic and tracer experiments have conducted using the rock cores with tailored parallel fracture, obtained at pilot borehole drilled in the vicinity of ventilation shaft. From the test results, hydraulic conductivity, diffusion coefficient, transport aperture, dispersion length and etc. was evaluated. Based on these test results, the influence of these parameters onto mass transport behavior of fractures sedimentary rocks was examined. For larger scale, such as several kilometer scale, the regional scale groundwater flow was examined using temperature data observed along the boreholes at Horonobe site. The results show that the low permeable zone between the boreholes might be estimated. (author)

Mass transport enhancement in redox flow batteries with corrugated fluidic networks

Science.gov (United States)

Lisboa, Kleber Marques; Marschewski, Julian; Ebejer, Neil; Ruch, Patrick; Cotta, Renato Machado; Michel, Bruno; Poulikakos, Dimos

2017-08-01

We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.

Effect of Orifice Nozzle Design and Input Power on Two-Phase Flow and Mass Transfer Characteristics

Energy Technology Data Exchange (ETDEWEB)

Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)

2016-04-15

It is necessary to investigate the input power as well as the mass transfer characteristics of the aeration process in order to improve the energy efficiency of an aerobic water treatment. The objective of this study is to experimentally investigate the effect of orifice nozzle design and input power on the flow and mass transfer characteristics of a vertical two-phase flow. The mass ratio, input power, volumetric mass transfer coefficient, and mass transfer efficiency were calculated using the measured data. It was found that as the input power increases the volumetric mass transfer coefficient increases, while the mass ratio and mass transfer efficiency decrease. The mass ratio, volumetric mass transfer coefficient, and mass transfer efficiency were higher for the orifice configuration with a smaller orifice nozzle area ratio. An empirical correlation was proposed to estimate the effect of mass ratio, input power, and Froude number on the volumetric mass transfer coefficient.

Physics design of fissile mass-flow monitoring system

International Nuclear Information System (INIS)

Mattingly, J.K.; March-Leuba, J.; Valentine, T.E.; Mihalczo, J.T.; Uckan, T.

1997-01-01

The system measures the flow rate and uranium-235 content in liquid or gas streams; it does not penetrate the process piping. A moderated fission neutron source is used to periodicially introduce a burst of thermal neutrons into the fluid stream to induce fission; delayed gamma emissions from the resulting fission fragments are detected by high-efficiency scintillators downstream of the neutron source. The fluid flow rate is measure from the time between initiation of the thermal neutron burst and detection of the fission product gamma emissions, and the U-235 content is inferred from the intensity of the gamma burst detected. Design of the fissile mass flow monitor requires satisfaction of several competing constraints. Efficient operation of the monitor requires that source-induced fission rate and detection efficiency be maximized while the source-induced background rate is simultaneoulsy minimized. Near optical nuclear design of the system was achieved using numerous Monte Carlo calculations and measurements. This paper addresses calculational aspects of the physics design for the system applied to UF 6 gas

Mass conservative fluid flow visualization for CFD velocity fields

International Nuclear Information System (INIS)

Li, Zhenquan; Mallinson, Gordon D.

2001-01-01

Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al., 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD data and using the existing method

Multiscale modeling of fluid flow and mass transport

Science.gov (United States)

Masuoka, K.; Yamamoto, H.; Bijeljic, B.; Lin, Q.; Blunt, M. J.

2017-12-01

In recent years, there are some reports on a simulation of fluid flow in pore spaces of rocks using Navier-Stokes equations. These studies mostly adopt a X-ray CT to create 3-D numerical grids of the pores in micro-scale. However, results may be of low accuracy when the rock has a large pore size distribution, because pores, whose size is smaller than resolution of the X-ray CT may be neglected. We recently found out by tracer tests in a laboratory using a brine saturated Ryukyu limestone and inject fresh water that a decrease of chloride concentration took longer time. This phenomenon can be explained due to weak connectivity of the porous networks. Therefore, it is important to simulate entire pore spaces even those of very small sizes in which diffusion is dominant. We have developed a new methodology for multi-level modeling for pore scale fluid flow in porous media. The approach is to combine pore-scale analysis with Darcy-flow analysis using two types of X-ray CT images in different resolutions. Results of the numerical simulations showed a close match with the experimental results. The proposed methodology is an enhancement for analyzing mass transport and flow phenomena in rocks with complicated pore structure.

Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

Science.gov (United States)

Kahveci, E. E.; Taymaz, I.

2018-03-01

In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor

Energy Technology Data Exchange (ETDEWEB)

Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno [University of Zagreb, Zagreb (Croatia)

2015-06-15

Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R{sup 2}=0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k{sub L}a=4,652-1,9807 h{sup -1}.

Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor

International Nuclear Information System (INIS)

Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno

2015-01-01

Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R 2 =0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k L a=4,652-1,9807 h -1

Asymptotic behavior of the mixed mass in Rayleigh–Taylor and Richtmyer–Meshkov instability induced flows

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ye; Cabot, William H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Thornber, Ben [The University of Sydney, School of Aerospace, Mechanical and Mechatronic Engineering, New South Wales 2006, Sydney (Australia)

2016-05-15

Rayleigh–Taylor instability (RTI) and Richtmyer–Meshkov instability (RMI) are serious practical issues in inertial confinement fusion research, and also have relevance to many cases of astrophysical fluid dynamics. So far, much of the attention has been paid to the late-time scaling of the mixed width, which is used as a surrogate to how well the fluids have been mixed. Yet, the actual amount of mixed mass could be viewed as a more direct indicator on the evolution of the mixing layers due to hydrodynamic instabilities. Despite its importance, there is no systematic study as yet on the scaling of the mixed mass for either the RTI or the RMI induced flow. In this article, the normalized mixed mass (Ψ) is introduced for measuring the efficiency of the mixed mass. Six large numerical simulation databases have been employed: the RTI cases with heavy-to-light fluid density ratios of 1.5, 3, and 9; the single shock RMI cases with density ratios of 3 and 20; and a reshock RMI case with density ratio of 3. Using simulated flow fields, the normalized mixed mass Ψ is shown to be more sensitive in discriminating the variation with Atwood number for the RTI flows. Moreover, Ψ is demonstrated to provide more consistent results for both the RTI and RMI flows when compared with the traditional mixedness parameters, Ξ and Θ.

Infrared Tomography: Data Distribution System for Real-time Mass Flow Rate Measurement

Directory of Open Access Journals (Sweden)

Ruzairi Abdul Rahim

2007-06-01

Full Text Available The system developed in this research has the objective of measuring mass flow rate in an online mode. If a single computer is used as data processing unit, a longer time is needed to produce a measurement result. In the research carried out by previous researcher shows about 11.2 seconds is needed to obtain one mass flow rate result in the offline mode (using offline data. This insufficient real-time result will cause problems in a feedback control process when applying the system on industrial plants. To increase the refreshing rate of the measurement result, an investigation on a data distribution system is performed to replace the existing data processing unit.

Computer programs for the numerical modelling of water flow in rock masses

International Nuclear Information System (INIS)

Croney, P.; Richards, L.R.

1985-08-01

Water flow in rock joints provides a very important possible route for the migration of radio-nuclides from radio-active waste within a repository back to the biosphere. Two computer programs DAPHNE and FPM have been developed to model two dimensional fluid flow in jointed rock masses. They have been developed to run on microcomputer systems suitable for field locations. The fluid flows in a number of jointed rock systems have been examined and certain controlling functions identified. A methodology has been developed for assessing the anisotropic permeability of jointed rock. A number of examples of unconfined flow into surface and underground openings have been analysed and ground water lowering, pore water pressures and flow quantities predicted. (author)

Micro Coriolis mass flow sensor with integrated resistive pressure sensors

NARCIS (Netherlands)

Groenesteijn, Jarno; Alveringh, Dennis; Schut, Thomas; Wiegerink, Remco J.; Sparreboom, Wouter; Lötters, Joost Conrad

2017-01-01

We report on novel resistive pressure sensors, integrated on-chip at the inlet- and outlet-channels of a micro Coriolis mass flow sensor. The pressure sensors can be used to measure the pressure drop over the Coriolis sensor which can be used to compensate pressure-dependent behaviour that might

Resistive pressure sensors integrated with a Coriolis mass flow sensor

NARCIS (Netherlands)

Alveringh, Dennis; Schut, Thomas; Wiegerink, Remco J.; Sparreboom, Wouter; Lötters, Joost Conrad

2017-01-01

We report on a novel resistive pressure sensor that is completely integrated with a Coriolis mass flow sensor on one chip, without the need for extra fabrication steps or different materials. Two pressure sensors are placed in-line with the Coriolis sensor without requiring any changes to the fluid

Mass transfer between gas and particles in a gas-solid trickle flow reactor

NARCIS (Netherlands)

Kiel, J.H.A.; Kiel, J.H.A.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

1992-01-01

Gas-solids mass transfer was studied for counter-current flow of gas and millimetre-sized solid particles over an inert packing at dilute phase or trickle flow conditions. Experimental data were obtained from the adsorption of water vapour on 640 and 2200 ¿m diameter molecular sieve spheres at

Study on flow and mass transport through fractured soft sedimentary rocks (Contact research)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Maekawa, Keisuke

2007-03-01

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of Koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Pottasium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock. (author)

Inventory model with cash flow oriented and time-dependent holding cost under permissible delay in payments

Directory of Open Access Journals (Sweden)

Tripathi R.P.

2013-01-01

Full Text Available This study develops an inventory model for determining an optimal ordering policy for non-deteriorating items and time-dependent holding cost with delayed payments permitted by the supplier under inflation and time-discounting. The discounted cash flows approach is applied to study the problem analysis. Mathematical models have been derived under two different situations i.e. case I: The permissible delay period is less than cycle time for settling the account and case II: The permissible delay period is greater than or equal to cycle time for settling the account. An algorithm is used to obtain minimum total present value of the costs over the time horizon H. Finally, numerical example and sensitivity analysis demonstrate the applicability of the proposed model. The main purpose of this paper is to investigate the optimal cycle time and optimal payment time for an item so that annual total relevant cost is minimized.

Source modulation-correlation measurement for fissile mass flow in gas or liquid fissile streams

International Nuclear Information System (INIS)

Mihalczo, J.T.; March-Leuba, J.A.; Valentine, T.E.; Abston, R.A.; Mattingly, J.K.; Mullens, J.A.

1996-01-01

The method of monitoring fissile mass flow on all three legs of a blending point, where the input is high-enriched uranium (HEU) and low-enriched uranium (LEU) and the product is PEU, can yield the fissile stream velocity and, with calibration, the [sup235]U content. The product of velocity and content integrated over the pipe gives the fissile mass flow in each leg. Also, the ratio of fissile contents in each pipe: HEU/LEU, HEU/PEU, and PEU/LEU, are obtained. By modulating the source on the input HEU pipe differently from that on the output pipe, the HEU gas can be tracked through the blend point. This method can be useful for monitoring flow velocity, fissile content, and fissile mass flow in HEU blenddown of UF[sub 6] if the pressures are high enough to contain some of the induced fission products. This method can also be used to monitor transfer of fissile liquids and other gases and liquids that emit radiation delayed from particle capture. These preliminary experiments with the Oak Ridge apparatus show that the method will work and the modeling is adequate

NextGen Flight Deck Surface Trajectory-Based Operations (STBO): Contingency Holds

Science.gov (United States)

Bakowski, Deborah Lee; Hooey, Becky Lee; Foyle, David C.; Wolter, Cynthia A.; Cheng, Lara W. S.

2013-01-01

The purpose of this pilot-in-the-loop taxi simulation was to investigate a NextGen Surface Trajectory-Based Operations (STBO) concept called "contingency holds." The contingency-hold concept parses a taxi route into segments, allowing an air traffic control (ATC) surface traffic management (STM) system to hold an aircraft when necessary for safety. Under nominal conditions, if the intersection or active runway crossing is clear, the hold is removed, allowing the aircraft to continue taxiing without slowing, thus improving taxi efficiency, while minimizing the excessive brake use, fuel burn, and emissions associated with stop-and-go taxi. However, when a potential traffic conflict exists, the hold remains in place as a fail-safe mechanism. In this departure operations simulation, the taxi clearance included a required time of arrival (RTA) to a specified intersection. The flight deck was equipped with speed-guidance avionics to aid the pilot in safely meeting the RTA. On two trials, the contingency hold was not released, and pilots were required to stop. On two trials the contingency hold was released 15 sec prior to the RTA, and on two trials the contingency hold was released 30 sec prior to the RTA. When the hold remained in place, all pilots complied with the hold. Results also showed that when the hold was released at 15-sec or 30-sec prior to the RTA, the 30-sec release allowed pilots to maintain nominal taxi speed, thus supporting continuous traffic flow; whereas, the 15-sec release did not. The contingency-hold concept, with at least a 30-sec release, allows pilots to improve taxiing efficiency by reducing braking, slowing, and stopping, but still maintains safety in that no pilots "busted" the clearance holds. Overall, the evidence suggests that the contingency-hold concept is a viable concept for optimizing efficiency while maintaining safety.

Measurement of the temperature and flow fields of the magnetically stabilized cross-flow N2 arc

International Nuclear Information System (INIS)

Sebald, N.

1980-01-01

A straight, steady-state cross-flow arc is burning in an N 2 wind tunnel. The arc is held in position by the balance of the Lorentz forces produced by an external magnetic field perpendicular to the arc axis and by the viscous forces of the gas flow acting on the arc column. The temperature field in the discharge is determined spectroscopically using the radiation of N I lines. For known local temperature the mass flow field inside the arc may be evaluated from the convective term of the energy equation and the continuity equation. This is done by expanding the terms of these two equations around the point of the temperature maximum into Fourier-Taylor series and determining coefficients of the same order and power. The solution of the resulting set of algebraic equations yields the unknown coefficients of the mass flow. The flow field obtained by these calculations shows a relatively strong counter-flow through the arc core. In the region for which the series expansions holds a partial structure pertaining to a closed double vortex can be recognized. The terms of the momentum equation are calculated on the basis of these results. In order to obtain a better understanding of the importance attributed to the individual local forces acting on the plasma, a simple model was devised which separates the momentum equation into gradient and curl terms. It is shown that viscosity as a damping mechanism is necessary for the existence of stationary flow fields as investigated in this work. (orig./CDS) 891 CDS/orig.- 892 ARA

The effect of the virtual mass force term on the stability of transient two-phase flow analysis

International Nuclear Information System (INIS)

Watanabe, Tadashi; Hirano, Masashi; Tanabe, Fumiya

1989-08-01

The effect of the virtual mass force term on the stability of transient two-phase flow analysis is studied. The objective form of the virtual mass acceleration is used. The virtual mass coefficient is determined from the stability condition of basic equations against infinitesimal high wave-number perturbations. The parameter is chosen so that a reasonable agreement between the analytical and experimental sound speed in two-phase flows can be obtained. A one-dimensional sedimentation problem is simulated by the MINCS code which is a tool for transient two-phase flow analysis. The stability analysis is performed for the numerical procedure. It is shown that calculated results are stabilized so long as the virtual mass coefficient satisfies the stability condition of differential equations. (author)

Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

Science.gov (United States)

Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

2016-09-01

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

Evaluation of mechanical integrity for helical coil hold-down spring of PLUS7TM fuel

International Nuclear Information System (INIS)

Choi, Ki Sung; Kim, Yong Hwan; Kwon, Jung Tack; Kim, Kyu Tae

2004-01-01

Nuclear fuel assembly is subject to hydraulic forces generated by primary coolant flow during reactor operation. These forces may be sufficient to overcome the fuel assembly weight thereby allowing the fuel assembly to lift off of its support. To provide a positive hold-down margin against the upward coolant flow forces, helical coil springs or leaf springs are installed in the fuel assemblies. An advanced fuel for Korean Standard Nuclear Power Plants (KSNP), PLUS7 fuel has developed to get the thermal margin increase, failure free and high seismic resistance, etc. And the new designed helical coil hold-down spring was introduced into PLUS7 fuel assembly. The purpose of this paper is to evaluate the mechanical integrity for the helical coil hold-down spring of PLUS7 fuel assembly

Measurement of mass flux in two-phase flow using combinations of Pitot tubes and gamma densitometers

International Nuclear Information System (INIS)

Hau, K.F.F.L.; Banerjee, S.

1981-01-01

New experimental data indicate that mass flux in cocurrent gas-liquid flows may be determined by the use of Pitot tubes in conjunction with a local mixture density measurement technique. The data were taken over a wide range of flow regimes in a horizontal pipe and included separated patterns such as stratified and annular flows. Local mixture densities were obtained by a computer-assisted algebraic reconstruction technique that used chordal average densities measured by traversing gamma beam attenuation. The results extend the applicability of this mass flux measurement technique well beyond the relatively homogeneous, high-pressure, steam-water flow situations originally studied by S. Banerjee and D.M. Nguyen. 13 refs

Mathematical Investigation of Fluid Flow, Mass Transfer, and Slag-steel Interfacial Behavior in Gas-stirred Ladles

Science.gov (United States)

Cao, Qing; Nastac, Laurentiu

2018-06-01

In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly.

Joint test rig for testing and calibrating of different methods of two-phase mass flow measurement

International Nuclear Information System (INIS)

Reimann, J.; Demski, A.; Hahn, H.; Harten, U.; John, H.; Megerle, A.; Mueller, S.; Pawlak, L.; Wanner, E.

1977-01-01

The steam-water loop was completed by building in two throttling valves upstream of the mixing chamber. By producing steam by throttling the total mass flow may be increased up to 35% compared to the former method of operating the loop. Furthermore, throttling stabilizes the single phase mass flow measurement. The data aquisition system and computation of the reference values has been finished. The computer program contains the equations of state of steam/water and the calibration curves for all signal transducers. The 5 beam γ-densitometer has been finished mechanically and supplied with the electronics. First calibration tests are fully satisfactory. The instrumentation of the air-water loop completed. At low quality the mass fluxes are increased by a factor of 5 compared with the steam-water-loop. The regime of dispersed bubble flow is fully reached in the test section. To detect flow regimes air-water as well as in steam-water flow, a local impedance probe was used. In addition, the phase distribution across the channel could be detected by traversing the probe. The boundaries of the air-water flow regimes detected by the probe are in good correspondance with other investigations. For the first time, such experiments have been carried out in horizontal steam-water flow. The results indicate that the region of slug flow becomes smaller with increasing pressure. (orig./RW) [de

Holding device for gas-cooled reactor fuel elements

International Nuclear Information System (INIS)

Hensolt, T.

1980-01-01

The sheathed fuel elements of the GCFR are inserted with their pedestal in a grid plate arranged below the reactor core and are clamped there. The clamping force as well as the force required for hydraulic holding-down against the flow pressure of the coolant are applied through the differential pressure between inlet and outlet of the coolant. (DG) [de

Selected ion flow tube mass spectrometry for on-line trace gas analysis in biology and medicine

Czech Academy of Sciences Publication Activity Database

Španěl, Patrik; Smith, D.

2007-01-01

Roč. 13, č. 1 (2007), s. 77-82 ISSN 1469-0667 R&D Projects: GA ČR GA202/06/0776 Institutional research plan: CEZ:AV0Z40400503 Keywords : selected ion flow tube mass spectroscopy (SIFT-MS) * breath analysis * breath metabolities * flowing afterglow mass spectrometry (FA-MS) Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.198, year: 2007

Scaling of Myocardial Mass to Flow and Morphometry of Coronary Arteries

OpenAIRE

Choy, Jenny Susana; Kassab, Ghassan S.

2008-01-01

There is no doubt that scaling relations exist between myocardial mass and morphometry of coronary vasculature. The purpose of this study is to quantify several morphological (diameter, length, and volume) and functional (flow) parameters of the coronary arterial tree in relation to myocardial mass. Eight normal porcine hearts of 117-244 g (mean of 177.5±32.7) were used in this study. Various coronary sub-trees of the Left Anterior Descending (LAD), Right Coronary (RCA) and Left Circumflex (L...

A Mass Conservative Numerical Solution for Two-Phase Flow in Porous Media With Application to Unsaturated Flow

DEFF Research Database (Denmark)

Celia, Michael A.; Binning, Philip John

1992-01-01

that the algorithm produces solutions that are essentially mass conservative and oscillation free, even in the presence of steep infiltrating fronts. When the algorithm is applied to the case of air and water flow in unsaturated soils, numerical results confirm the conditions under which Richards's equation is valid....... Numerical results also demonstrate the potential importance of air phase advection when considering contaminant transport in unsaturated soils. Comparison to several other numerical algorithms shows that the modified Picard approach offers robust, mass conservative solutions to the general equations...

Analysis of Ketones by Selected Ion Flow Tube Mass Spectrometry

Czech Academy of Sciences Publication Activity Database

Smith, D.; Wang, T.; Španěl, Patrik

2003-01-01

Roč. 17, - (2003), s. 2655-2660 ISSN 0951-4198 R&D Projects: GA ČR GA202/03/0827; GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : mass spectrometry * selected ion flow tube * ketones Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.789, year: 2003

EVALUATION OF THE IMPACT OF INNOVATIVE PROJECTS ON THE COMPETITIVENESS OF AGRICULTURAL HOLDINGS IN SLOVAK REPUBLIC

Directory of Open Access Journals (Sweden)

Ľubica RUMANOVSKÁ

2013-01-01

Full Text Available The scientific paper evaluates the impact of innovative projects on the competitiveness of agricultural holdings in SR. Evaluation of the impact of innovative projects on competitiveness of agricultural holdings was realized on the selected holdings in Nitra and Trnava region. For the evaluation was used RCR coefficient. With the use of RCR coefficient could be confirmed the scientific hypothesis - The innovative projects realized through Program for rural development SR 2007-2013 have positive impact on competitiveness of agricultural holdings. The possibilities for EU financial support for innovative projects in SR represent important source for introduction of new innovative technologies into production process and in future they can significantly contribute to the growth of competitiveness of agricultural subjects. Therefore, to increase competitiveness of agricultural holdings it is important to focus on modernization of machinery and buildings, use of natural sources for energy production, but also to increase the education and the flow of information between rural inhabitants, mainly farmers. In competitive area of EU agricultural sector it is necessary that agricultural holdings will innovate, not only to create independent flow of innovative products and knowledge, but also to increase its value on internal market. Agricultural holdings –receivers of financial support – have expressed the opinion that financial support realized through PRD SR 2007-2013 had definitely allowed them to implement new processes and products.

In vitro holding and PLD-repair. Pt. 2

International Nuclear Information System (INIS)

Stevenson, A.F.G.; Palackal, T.; Lange, C.S.

1989-01-01

The repair of potentially lethal damage (PLDR) in mammalian cells is expected to be better in quiescent cultures since PLD is supposedly fixed during cycle progression. Plateau phase cultures, therefore, serve as models because of assumed mitotic quiescence. Four established cell lines (V79, CHO, L5178Y and HELA) and one euploid cell strain IMR-90 have been analysed by flow cytometry and electron microscopy to address questions on quiescence in the plateau phase and the effect of holding (induction of quiescence by nutrient privation). In contrast to commonly held views, our results indicate that the quiescent fraction in cultures from transformed cells is exceedingly low (1% or less). Plateau phase cultures of transformed cells are constantly turning over. Euploid cells like the IMR-90 show true quiescence in the plateau phase. Holding causes typical cytopathological changes. These changes have been ultrastructurely characterised. Resistant sub-populations of cells can be selected out under holding-conditions. Such selected cells show completely different radiobiological characteristics, which raise questions on the interpretation of data on PLDR. (orig.)

Further development of drag bodies for the measurement of mass flow rates during blowdown experiments

International Nuclear Information System (INIS)

Brockmann, E.; John, H.; Reimann, J.

1983-01-01

Drag bodies have already been used for sometime for the measurement of mass flow rates in blowdown experiments. Former research concerning the drag body behaviour in non-homogeneous two-phase flows frequently dealt with special effects by means of theoretical models only. For pipe flows most investigations were conducted for ratios of drag plate area to pipe cross section smaller 0.02. The present paper gives the results of experiments with drag bodies in a horizontal, non-homogeneous two-phase pipe flow with slip, which were carried through under the sponsorship of the German Ministry for Research and Technology (BMFT). Special interest was layed on the behaviour of the drag coefficient in stationary flows and at various cross sectional ratios. Both design and response of various drag bodies, which were developed at the Battelle-Institut, were tested in stationary and instationary two-phase flows. The influences of density and velocity profiles as well as the drag body position were studied. The results demonstrate, that the drag body is capable of measuring mass flow rates in connection with a gamma densitometer also in non-homogeneous two-phase flows. Satisfying results could be obtained, using simply the drag coefficient which was determined from single-phase flow calibrations

Aerodynamics, heat and mass transfer in steam-aerosol turbulent flows in containment

Energy Technology Data Exchange (ETDEWEB)

Nigmatulin, B.I.; Pershukov, V.A.; Ris, V.V. [Research & Engineering Centre of Nuclear Plants Safety, Moscow (Russian Federation)] [and others

1995-09-01

In this report an analysis of aerodynamic and heat transfer processes at the blowdown of gas-dispersed mixture into the containment volume is presented. A few models for description of the volume averaged and local characteristics are analyzed. The mathematical model for description of the local characteristics of the turbulent gas-dispersed flows was developed. The calculation of aerodynamic, heat and mass transfer characteristics was based on the Navier-Stokes, energy and gas mass fractions conservation equations. For calculation of dynamics and deposition of the aerosols the original diffusion-inertia model is developed. The pulsating characteristics of the gaseous phase were calculated on the base (k-{xi}) model of turbulence with modification to account thermogravitational force action and influence of particle mass loading. The appropriate boundary conditions using the {open_quotes}near-wall function{close_quotes} approach was obtained. Testing of the mathematical models and boundary conditions has shown a good agreement between computation and data of comparison. The described mathematical models were applied to two- and three dimensional calculations of the turbulent flow in containment at the various stages of the accident.

Piecewise mass flows within a solar prominence observed by the New Vacuum Solar Telescope

Science.gov (United States)

Li, Hongbo; Liu, Yu; Tam, Kuan Vai; Zhao, Mingyu; Zhang, Xuefei

2018-06-01

The material of solar prominences is often observed in a state of flowing. These mass flows (MF) are important and useful for us to understand the internal structure and dynamics of prominences. In this paper, we present a high resolution Hα observation of MFs within a quiescent solar prominence. From the observation, we find that the plasma primarily has a circular motion and a downward motion separately in the middle section and legs of the prominence, which creates a piecewise mass flow along the observed prominence. Moreover, the observation also shows a clear displacement of MF's velocity peaks in the middle section of the prominence. All of these provide us with a detailed record of MFs within a solar prominence and show a new approach to detecting the physical properties of prominence.

Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

Science.gov (United States)

Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

2011-01-01

Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

Do business groups affect corporate cash holdings? Evidence from a transition economy

Directory of Open Access Journals (Sweden)

Weixing Cai

2016-03-01

Full Text Available We examine whether business groups’ influence on cash holdings depends on ownership. Group affiliation can increase firms’ agency costs or benefit firms by providing an internal capital market, especially in transition economies characterized by weak investor protection and difficult external capital acquisition. A hand-collected dataset of Chinese firms reveals that group affiliation decreases cash holdings, alleviating the free-cash-flow problem of agency costs. State ownership and control of listed firms moderate this benefit, which is more pronounced when the financial market is less liquid. Group affiliation facilitates related-party transactions, increases debt capacity and decreases investment-cash-flow sensitivity and overinvestment. In transitional economies, privately controlled firms are more likely to benefit from group affiliation than state-controlled firms propped up by the government.

Triaxial slide-hold-slide shear experiment of sedimentary rock under drain condition

International Nuclear Information System (INIS)

Kishida, Kiyoshi; Yano, Takao; Elsworth, Derek; Yasuhara, Hideaki; Nakashima, Shinichiro

2011-01-01

When discussing the mechanical and hydro-mechanical properties of rock masses under the long-term holding, the variation of rock structure and the change of shear band condition should be discussed in considering the effect of thermal and chemical influences. In this research, the triaxial shear experiment under drain condition was conducted through sedimentary rock, and in the residual stress state, the slide-hold-slide processes were applied to these triaxial experiments. The experiments were carried out in 3 kinds of confining conditions and 2 kinds of thermal conditions. Consequently, the healing phenomena can be observed and the shear strength recovery is also confirmed in process of the holding time. (author)

Fluid Dynamics And Mass Transfer In Two-Fluid Taylor-Couette Flow

International Nuclear Information System (INIS)

Baier, G.; Graham, M.D.

1998-01-01

The Taylor-Couette instability of a single liquid phase can be used to enhance mass transfer processes such as filtration and membrane separations. We consider here the possibility of using this instability to enhance interphase transport in a two-fluid systems, with a view toward improved liquid-liquid extractions for biotechnology applications. We investigate the centrifugal instability of a pair of radially stratified immiscible liquids in the annular gap between concentric, corotating cylinders: two-fluid Taylor-Couette flow. Experiments show that a two-layer flow with a well-defined interface and Taylor vortices in each phase can be obtained. The experimental results are in good agreement with predictions of inviscid arguments based on a two-phase extension of Rayleigh's criterion, as well as with detailed linear stability calculations. For a given geometry, the most stable configuration occurs for fluids of roughly (exactly in the inviscid limit) equal dynamic viscosities. A number of preliminary mass transfer experiments have also been performed, in the presence of axial counterflow. The onset of Taylor vortices coincides with a clear decrease in the extent of axial dispersion and an increase in the rate of interphase transport, thus suggesting that this flow geometry may provide an effective means for countercurrent chromatographic separations

The financial determinants of corporate cash holdings in an oil rich country: Evidence from Kingdom of Saudi Arabia

Directory of Open Access Journals (Sweden)

Muncef Guizani

2017-09-01

Full Text Available This paper investigates the determinants of the cash holdings for a sample of Saudi firms over the period 2006–2014, using static and dynamic panel models. Our results show that leverage, firm size, capital expenditure, net working capital and cash flow volatility are important in determining cash holdings. When we divide our sample into two sub-samples: petrochemical and non-petrochemical firms, our results show a significant difference between the determinants of cash holdings of the two groups of firms. We also investigate the characteristics of high liquid firms (conservative firms. The results indicate that conservative firms are less leveraged, have large size, have low investment expenditures and have low cash flow fluctuation. Furthermore, dynamic panel estimation indicates that Saudi firms adjust their liquidity holdings quickly towards an endogenous target cash ratio.

Gas-liquid mass transfer in a cross-flow hollow fiber module : Analytical model and experimental validation

NARCIS (Netherlands)

Dindore, V. Y.; Versteeg, G. F.

2005-01-01

The cross-flow operation of hollow fiber membrane contactors offers many advantages and is preferred over the parallel-flow contactors for gas-liquid mass transfer operations. However, the analysis of such a cross-flow membrane gas-liquid contactor is complicated due to the change in concentrations

Ideal stability of cylindrical plasma in the presence of mass flow

International Nuclear Information System (INIS)

Bondeson, A.; Iacono, R.

1988-11-01

The ideal stability of cylindrical plasma with mass flows is investigated using the guiding centre plasma (GCP) model of Grad. For rotating plasmas, the kinetic treatment of the parallel motion in GCP gives significantly different results than fluid models, where the pressures are obtained from equations of state. In particular, GCP removes the resonance with slow magnetoacoustic waves and the loss of stability that results in magnetohydrodynamics (MHD) for near-soni flows. Because of the strong kinetic damping of the sound waves in an isothermal plasma, the slow waves have little influence on plasma stability in GCP at low β. In the large aspect ratio, low-β tokamak ordering, Alfvenic flows are needed to change the ideal GCP stability significantly. At lowest order in the inverse aspect ratio, flow can be favorable or unfavorable for stability of local modes depending on the profiles, but external kinks are always destilized by flow if the velocity vanishes at the edge. For high-β, reversed field pinch equilibria, numerical computations show that flow can be stabilizing for local modes, but external modes are destabilized by flow. It is shown that in three dimensions, the MHD equilibrium problem becomes hyperbolic for arbitrarily small flows across the magnetic field, whereas in GCP the equilibrium remains elliptic for sub-Alfvenic flows. (author) 7 figs., 1 tab, 32 refs

MASS TRANSFER CONTROL OF A BACKWARD-FACING STEP FLOW BY LOCAL FORCING- EFFECT OF REYNOLDS NUMBER

Directory of Open Access Journals (Sweden)

Zouhaier MEHREZ

2011-01-01

Full Text Available The control of fluid mechanics and mass transfer in separated and reattaching flow over a backward-facing step by a local forcing, is studied using Large Eddy Simulation (LES.To control the flow, the local forcing is realized by a sinusoidal oscillating jet at the step edge. The Reynolds number is varied in the range 10000 ≤ Re≤ 50000 and the Schmidt number is fixed at 1.The found results show that the flow structure is modified and the local mass transfer is enhanced by the applied forcing. The observed changes depend on the Reynolds number and vary with the frequency and amplitude of the local forcing. For the all Reynolds numbers, the largest recirculation zone size reduction is obtained at the optimum forcing frequency St = 0.25. At this frequency the local mass transfer enhancement attains the maximum.

CCC, Heat Flow and Mass Flow in Liquid Saturated Porous Media

International Nuclear Information System (INIS)

Mangold, D.C.; Lippmann, M.J.; Bodvarsson, G.S.

1982-01-01

1 - Description of problem or function: The numerical model CCC (conduction-convection-consolidation) solves the heat and mass flow equations for a fully, liquid-saturated, anisotropic porous medium and computes one-dimensional (vertical) consolidation of the simulated systems. The model has been applied to problems in the fields of geothermal reservoir engineering, aquifer thermal energy storage, well testing, radioactive waste isolation, and in situ coal combustion. The code has been validated against analytic solutions for fluid and heat flow, and against a field experiment for underground storage of hot water. 2 - Method of solution: The model employs the Integrated Finite Difference Method (IFDM) in discretizing the saturated porous medium and formulating the governing equations. The sets of equations are sol- ved by an iterative solution technique. The vertical deformation of the medium is calculated using the one-dimensional consolidation theory of Terzaghi. 3 - Restrictions on the complexity of the problem: Maximum of 12 materials. It is assumed that: (a) Darcy's law adequately describes fluid movement through fractured and porous media. (b) The rock and fluid are in thermal equilibrium at any given time. (c) Energy changes due to the fluid compressibility, acceleration and viscous dissipation are neglected. (d) One-dimensional consolidation theory adequately describes the vertical deformation of the medium

Mass flow discharge and total temperature characterisation of a pyrotechnic gas generator formulation for airbag systems

Energy Technology Data Exchange (ETDEWEB)

Neutz, Jochen; Koenig, Andreas [Fraunhofer Institut fuer Chemische Technologie ICT, Pfinztal (Germany); Knauss, Helmut; Jordan, Sebastian; Roediger, Tim; Smorodsky, Boris [Universitaet Stuttgart (Germany). Institut fuer Aerodynamik und Gasdynamik; Bluemcke, Erich Walter [AUDI AG, Department I/EK-523, Ingolstadt (Germany)

2009-06-15

The mass flow characteristics of gas generators for airbag applications have to comply with a number of requirements for an optimal deployment of the airbag itself. Up to now, the mass flow was determined from pressure time histories of so-called can tests. This procedure suffers from the missing knowledge on the temperature of the generated gas entering the can. A new test setup described in this paper could overcome this problem by providing highly time resolved information on the gas's total temperature and the mass flow of the generator. The test setup consisted of a combustion chamber with a specially designed Laval nozzle in combination with a temperature sensor of high time resolution. The results showed a high time resolved temperature signal, which was disturbed by the formation of a slag layer on the sensor. Plausibility considerations with experimentally and thermodynamically determined combustion temperatures led to satisfying results for the overall temperature as characteristic parameter of airbag inflating gases flows from pyrotechnics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Molten Fuel Mass Assessment for Channel Flow Blockage Event in CANDU6

International Nuclear Information System (INIS)

Lee, Kwang Ho; Kim, Yong Bae; Choi, Hoon; Park, Dong Hwan

2011-01-01

In CANDU6, a fuel channel flow blockage causes a sudden reduction of flow through the blocked channel. Depending on the severity of the blockage, the reduced flow through the channel can result in severe heat up of the fuel, hence possibly leading to pressure tube and calandria tube failure. If the calandria tube does not fail the fuel and sheath would continue to heat up, and ultimately melting could occur. Eventually, molten material runs down onto the pressure tube. Even a thin layer of molten material in contact with the pressure tube causes the pressure tube and calandreia tube to heat up rapidly. The thermal transient is so rapid that failure temperatures are reached quickly. After channel failure, the contents of the channel, consisting of superheated coolant, fission products and possibly overheated of molten fuel, are rapidly discharged into the moderator. Fuel discharged into the moderator is quenched and cooled. The rapid discharge of hot fuel and coolant into the calandria causes the moderator pressure and temperature to increase, which may cause damage to some in-core components. Thus, the assessment results of molten fuel mass are inputs to the in-core damage analysis. In this paper, the analysis methodology and results of molten fuel mass assessment for the channel flow blockage event are presented

Heat and Mass Transfer on Squeezing Unsteady MHD Nano fluid Flow between Parallel Plates with Slip Velocity Effect

International Nuclear Information System (INIS)

Singh, K.; Rawat, S. K.; Kumar, M.

2016-01-01

Heat and mass transfer behavior of unsteady flow of squeezing between two parallel plates in the sight of uniform magnetic field with slip velocity effect is investigated. The governing equations representing fluid flow have been transformed into nonlinear ordinary differential equations using similarity transformation. The equations thus obtained have been solved numerically using Runge-Kutta-Fehlberg method with shooting technique. Effects on the behavior of velocity, temperature, and concentration for various values of relevant parameters are illustrated graphically. The skin-friction coefficient and heat and mass transfer rate are also tabulated for various governing parameters. The results indicate that, for nano fluid flow, the rates of heat and mass transfer are inversely proportional to nanoparticle volume fraction and magnetic parameter. The rate of mass transfer increases with increasing values of Schmidt number and squeeze number.

The respective roles of bulk friction and slip velocity during a granular mass flow

Science.gov (United States)

Staron, Lydie

2016-04-01

Catastrophic granular mass flows form an important natural hazard. Mitigation has motivated numerous studies on the properties of natural granular flows, and in particular, their ability to travel long distances away from the release point. The mobility of granular flows is commonly characterised through the definition of rheological properties and effective friction. Yet, it is widely accepted that the description in term of effective friction may include various lubrication effects, softening at the base of the flow and large slip velocities being a most likely one. In this case, flow bulk properties may obliterate the flow boundary conditions. In this contribution, we investigate how disentangling bulk properties from boundary conditions may improve our understanding of the flow. Using discrete simulations, we induce increasing slip velocities in different flow configurations. We show that increased mobility may be achieved without changing bulk properties. The results are interpreted in terms of a Robin-Navier slip condition and implemented in a continuum Navier-Stokes solver. We quantify the respective role of rheological bulk properties and boundary conditions in the general behaviour of a transient mass flow. We show that omitting the description of boundary conditions leads to misinterpretation of the flow properties. The outcome is discussed in terms of models reliability. References P.-Y. Lagrée et al, The granular column collapse as a continuum: validity of a two-dimensional Navier-Stokes model with the mu(I) rheology, J. Fluid Mech. 686, 378-408 (2011) L. Staron and E. Lajeunesse, Understanding how the volume affects the mobility of dry debris flows, Geophys. Res. Lett. 36, L12402 (2009) L. Staron, Mobility of long-runout rock flows: a discrete numerical investigation, Geophys. J. Int. 172, 455-463 (2008)

Non-basal dislocations should be accounted for in simulating ice mass flow

Science.gov (United States)

Chauve, T.; Montagnat, M.; Piazolo, S.; Journaux, B.; Wheeler, J.; Barou, F.; Mainprice, D.; Tommasi, A.

2017-09-01

Prediction of ice mass flow and associated dynamics is pivotal at a time of climate change. Ice flow is dominantly accommodated by the motion of crystal defects - the dislocations. In the specific case of ice, their observation is not always accessible by means of the classical tools such as X-ray diffraction or transmission electron microscopy (TEM). Part of the dislocation population, the geometrically necessary dislocations (GNDs) can nevertheless be constrained using crystal orientation measurements via electron backscattering diffraction (EBSD) associated with appropriate analyses based on the Nye (1950) approach. The present study uses the Weighted Burgers Vectors, a reduced formulation of the Nye theory that enables the characterization of GNDs. Applied to ice, this method documents, for the first time, the presence of dislocations with non-basal [ c ] or Burgers vectors. These [ c ] or dislocations represent up to 35% of the GNDs observed in laboratory-deformed ice samples. Our findings offer a more complex and comprehensive picture of the key plasticity processes responsible for polycrystalline ice creep and provide better constraints on the constitutive mechanical laws implemented in ice sheet flow models used to predict the response of Earth ice masses to climate change.

Generalized Couette Poiseuille flow with boundary mass transfer

Science.gov (United States)

Marques, F.; Sanchez, J.; Weidman, P. D.

1998-11-01

A generalized similarity formulation extending the work of Terrill (1967) for Couette Poiseuille flow in the annulus between concentric cylinders of infinite extent is given. Boundary conditions compatible with the formulation allow a study of the effects of inner and outer cylinder transpiration, rotation, translation, stretching and twisting, in addition to that of an externally imposed constant axial pressure gradient. The problem is governed by [eta], the ratio of inner to outer radii, a Poiseuille number, and nine Reynolds numbers. Single-cylinder and planar problems can be recovered in the limits [eta][rightward arrow]0 and [eta][rightward arrow]1, respectively. Two coupled primary nonlinear equations govern the meridional motion generated by uniform mass flux through the porous walls and the azimuthal motion generated by torsional movement of the cylinders; subsidiary equations linearly slaved to the primary flow govern the effects of cylinder translation, cylinder rotation, and an external pressure gradient. Steady solutions of the primary equations for uniform source/sink flow of strength F through the inner cylinder are reported for 0[less-than-or-eq, slant][eta][less-than-or-eq, slant]1. Asymptotic results corroborating the numerical solutions are found in different limiting cases. For F0 is more complex in that unique solutions are found at low Reynolds numbers, a region of triple solutions exists at moderate Reynolds numbers, and a two-cell solution prevails at large Reynolds numbers. The subsidiary linear equations are solved at [eta]=0.5 to exhibit the effects of cylinder translation, rotation, and an axial pressure gradient on the source/sink flows.

Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

Science.gov (United States)

Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

Flow and Mass Transfer Performance in Short Pin-Fin Channels with Different Fin Shapes

OpenAIRE

Goldstein, R. J.; Chen, S. B.

1998-01-01

The mass transfer (analogous to heat transfer) and pressure loss characteristics of staggered short pin-fin arrays are investigated experimentally in the range of Reynolds number 3000 to 18,000 based on fin diameter and mean approach-flow velocity. Three different shapes of fins with aspect ratio of 2 are examined: one uniform-diameter circular fin (UDCF) and two stepped-diameter circular fins (SDCF1 and SDCF2). Flow visualization using oil-lampblack reveals complex flow characteristics assoc...

Flow regime transition and heat transfer model at low mass flux condition in a post-dryout region

International Nuclear Information System (INIS)

Jeong, Hae Yong

1996-02-01

The post-dryout flow regime transition criterion from inverted annular flow (IAF) to agitated inverted annular flow (AIAF) is suggested based on the hyperbolicity breaking concept. The hyperbolicity breaking represents a bifurcation point where a sudden flow transition occurs. The hyperbolicity breaking concept is applied to describe the flow regime transition from IAF to AIAF by the growth of disturbance on liquid core surface. The resultant correlation has the similar form to Takenaka's empirical one. To validate the proposed model, it is applied to predict Takenake's experimental results using R-113 refrigerant with four different tube diameters of 3, 5, 7 and 10 mm. The proposed model gives accurate predictions for the tube diameters of 7 and 10 mm. As the tube diameter decreases, the differences between the predictions and the experimental results slightly increase. The flow regime transition from AIAF to dispersed flow (DF) is described by the drift flux model. It is shown that the transition criterion can be well predicted if the droplet sizes in dispersed flow are evaluated appropriately. Existing mechanistic post-dryout models result in fairly good predictions when the mass flux is high or when the film dryout occurs. However, the predictions by these models become poor at low mass flux at which the flow regime before dryout is believed to be churn-turbulent. This is because the constitutive relations and/or the imposed assumptions used in the models become erroneous at low mass flux. The droplet size predicted by the correlation used in the model becomes unrealistically large. In addition, the single phase vapor heat transfer correlation becomes invalid at low mass flux condition. To develop a mechanistic post-dryout model which is available at low mass flux condition, the entrainment mechanisms and the entrained droplet sizes with relation to the flow regimes are investigated. Through the analysis of many experimental post-dryout data, it is shown that

Flow pattern-based mass and heat transfer and frictional drag of gas-non-Newtonian liquid flow in helical coil: two- and three-phase systems

Science.gov (United States)

Thandlam, Anil Kumar; Das, Chiranjib; Majumder, Subrata Kumar

2017-04-01

Investigation of wall-liquid mass transfer and heat transfer phenomena with gas-Newtonian and non-Newtonian fluids in vertically helical coil reactor have been reported in this article. Experiments were conducted to investigate the effect of various dynamic and geometric parameters on mass and heat transfer coefficients in the helical coil reactor. The flow pattern-based heat and mass transfer phenomena in the helical coil reactor are highlighted at different operating conditions. The study covered a wide range of geometric parameters such as diameter of the tube ( d t ), diameter of the coil ( D c ), diameter of the particle ( d p ), pitch difference ( p/D c ) and concentrations of non-Newtonian liquid. The correlation models for the heat and mass transfer coefficient based on the flow pattern are developed which may be useful in process scale-up of the helical coil reactor for industrial application. The frictional drag coefficient was also estimated and analyzed by mass transfer phenomena based on the electrochemical method.

Entrainment of bed material by Earth-surface mass flows: review and reformulation of depth-integrated theory

Science.gov (United States)

Iverson, Richard M.; Chaojun Ouyang,

2015-01-01

Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass- and momentum-conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must in general satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear-traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

ULTRAVIOLET SPECTROSCOPIC ANALYSIS OF TRANSIENT MASS FLOW OUTBURST IN U CEPHEI

Energy Technology Data Exchange (ETDEWEB)

Tupa, Peter R.; DeLeo, Gary G.; McCluskey, George E. [Physics Department, Lehigh University, Bethlehem, PA 18015 (United States); Kondo, Yoji [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sahade, Jorge [Facultad de Ciencias Astronómicas, Paseo del Bosque s/n, B1900FWA-La Plata (Argentina); Giménez, Alvaro [Centro de Astrobiologia, CSIC/INTA, Carretera de Torrejon a Ajalvir, E-28850 Torrejon de Ardoz (Madrid) (Spain); Caton, Daniel B., E-mail: pet205@lehigh.edu [Appalachian State University, Boone, NC 28608 (United States)

2013-09-20

Spectra from the International Ultraviolet Explorer taken in 1989 September over one full orbital period of U Cephei (U Cep, HD 5796) are analyzed. The TLUSTY and SYNSPEC stellar atmospheric simulation programs are used to generate synthetic spectra to which U Cep continuum levels are normalized. Absorption lines attributed to the photosphere are divided out to isolate mass flow and accretion spectra. A radial velocity curve is constructed for conspicuous gas stream features, and shows evidence for a transient flow during secondary eclipse with outward velocities ranging between 200 and 350 km s{sup –1}, and a number density of (3 ± 2) × 10{sup 10} cm{sup –3}. The validity of C IV 1548 and 1550 and Si IV 1393 and 1402 lines are re-examined in the context of extreme rotational blending effects. A G-star to B-star mass transfer rate of (5 ± 4) × 10{sup –9} M{sub ☉} yr{sup –1} is calculated as an approximate upper limit, and a model system is presented.

ULTRAVIOLET SPECTROSCOPIC ANALYSIS OF TRANSIENT MASS FLOW OUTBURST IN U CEPHEI

International Nuclear Information System (INIS)

Tupa, Peter R.; DeLeo, Gary G.; McCluskey, George E.; Kondo, Yoji; Sahade, Jorge; Giménez, Alvaro; Caton, Daniel B.

2013-01-01

Spectra from the International Ultraviolet Explorer taken in 1989 September over one full orbital period of U Cephei (U Cep, HD 5796) are analyzed. The TLUSTY and SYNSPEC stellar atmospheric simulation programs are used to generate synthetic spectra to which U Cep continuum levels are normalized. Absorption lines attributed to the photosphere are divided out to isolate mass flow and accretion spectra. A radial velocity curve is constructed for conspicuous gas stream features, and shows evidence for a transient flow during secondary eclipse with outward velocities ranging between 200 and 350 km s –1 , and a number density of (3 ± 2) × 10 10 cm –3 . The validity of C IV 1548 and 1550 and Si IV 1393 and 1402 lines are re-examined in the context of extreme rotational blending effects. A G-star to B-star mass transfer rate of (5 ± 4) × 10 –9 M ☉ yr –1 is calculated as an approximate upper limit, and a model system is presented

Electric Holding Company Areas

Data.gov (United States)

Department of Homeland Security — Holding companies are electric power utilities that have a holding company structure. This vector polygon layer represents the area served by electric power holding...

Dry-out heat fluxes of falling film and low-mass flux upward-flow in heated tubes

International Nuclear Information System (INIS)

Koizumi, Yasuo; Ueda, Tatsuhiro; Matsuo, Teruyuki; Miyota, Yukio

1998-01-01

Dry-out heat fluxes were investigated experimentally for a film flow falling down on the inner surface of vertical heated-tubes and for a low mass flux forced-upward flow in the tubes using R 113. This work followed the study on those for a two-phase natural circulation system. For the falling film boiling, flow state observation tests were also performed, where dry-patches appearing and disappearing repeatedly were observed near the exit end of the heated section at the dry-out heat flux conditions. Relation between the dry-out heat flux and the liquid film flow rate is analyzed. The dry-out heat fluxes of the low mass flux upflow are expressed well by the correlation proposed in the previous work. The relation for the falling film boiling shows a similar trend to that for the upflow boiling, however, the dry-out heat fluxes of the falling film are much lower, approximately one third, than those of the upward flow. (author)

Effect of distributive mass of spring on power flow in engineering test

Science.gov (United States)

Sheng, Meiping; Wang, Ting; Wang, Minqing; Wang, Xiao; Zhao, Xuan

2018-06-01

Mass of spring is always neglected in theoretical and simulative analysis, while it may be a significance in practical engineering. This paper is concerned with the distributive mass of a steel spring which is used as an isolator to simulate isolation performance of a water pipe in a heating system. Theoretical derivation of distributive mass effect of steel spring on vibration is presented, and multiple eigenfrequencies are obtained, which manifest that distributive mass results in extra modes and complex impedance properties. Furthermore, numerical simulation visually shows several anti-resonances of the steel spring corresponding to impedance and power flow curves. When anti-resonances emerge, the spring collects large energy which may cause damage and unexpected consequences in practical engineering and needs to be avoided. Finally, experimental tests are conducted and results show consistency with that of the simulation of the spring with distributive mass.

Architecture for improved mass transport and system performance in redox flow batteries

Science.gov (United States)

Houser, Jacob; Pezeshki, Alan; Clement, Jason T.; Aaron, Douglas; Mench, Matthew M.

2017-05-01

In this work, electrochemical performance and parasitic losses are combined in an overall system-level efficiency metric for a high performance, all-vanadium redox flow battery. It was found that pressure drop and parasitic pumping losses are relatively negligible for high performance cells, i.e., those capable of operating at a high current density while at a low flow rate. Through this finding, the Equal Path Length (EPL) flow field architecture was proposed and evaluated. This design has superior mass transport characteristics in comparison with the standard serpentine and interdigitated designs at the expense of increased pressure drop. An Aspect Ratio (AR) design is discussed and evaluated, which demonstrates decreased pressure drop compared to the EPL design, while maintaining similar electrochemical performance under most conditions. This AR design is capable of leading to improved system energy efficiency for flow batteries of all chemistries.

Internal hydraulic control in the Little Belt, Denmark - observations of flow configurations and water mass formation

Science.gov (United States)

Holtegaard Nielsen, Morten; Vang, Torben; Chresten Lund-Hansen, Lars

2017-12-01

Internal hydraulic control, which occurs when stratified water masses are forced through an abrupt constriction, plays an enormous role in nature on both large and regional scales with respect to dynamics, circulation, and water mass formation. Despite a growing literature on this subject surprisingly few direct observations have been made that conclusively show the existence of and the circumstances related to internal hydraulic control in nature. In this study we present observations from the Little Belt, Denmark, one of three narrow straits connecting the Baltic Sea and the North Sea. The observations (comprised primarily of along-strait, detailed transects of salinity and temperature; continuous observations of flow velocity, salinity, and temperature at a permanent station; and numerous vertical profiles of salinity, temperature, fluorescence, and flow velocity in various locations) show that internal hydraulic control is a frequently occurring phenomenon in the Little Belt. The observations, which are limited to south-going flows of approximately two-layered water masses, show that internal hydraulic control may take either of two configurations, i.e. the lower or the upper layer being the active, accelerating one. This is connected to the depth of the pycnocline on the upstream side and the topography, which is both deepening and contracting toward the narrow part of the Little Belt. The existence of two possible flow configurations is known from theoretical and laboratory studies, but we believe that this has never been observed in nature and reported before. The water masses formed by the intense mixing, which is tightly connected with the presence of control, may be found far downstream of the point of control. The observations show that these particular water masses are associated with chlorophyll concentrations that are considerably higher than in adjacent water masses, showing that control has a considerable influence on the primary production and

Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber

NARCIS (Netherlands)

Li, Jiuyi; Busscher, Henk J.; Norde, Willem; Sjollema, Jelmer

2011-01-01

In order to investigate bacterium-substratum interactions, understanding of bacterial mass transport is necessary. Comparisons of experimentally observed initial deposition rates with mass transport rates in parallel-plate-flow-chambers (PPFC) predicted by convective-diffusion yielded deposition

Method of measuring the mass flow rate of a substance entering a cocurrent fluid stream

International Nuclear Information System (INIS)

Cochran, H.D. Jr.

1978-01-01

An improved method of monitoring the mass flow rate of a substance entering a coherent fluid stream is described. The method very basically consists of heating equal sections of the fluid stream above and below the point of entry of the substance to be monitored, and measuring and comparing the resulting change in temperature of the sections. Advantage is taken of the difference in thermal characteristics of the fluid and the substance to be measured to correlate temperature differences in the sections above and below the substance feed point for providing an indication of the mass flow rate of the substance

Mass and heat transfer at the outer surface of helical coils under single and two phase flow

International Nuclear Information System (INIS)

Abdel-Aziz, M.H.; Nirdosh, I.; Sedahmed, G.H.

2016-01-01

Highlights: • The work aims to develop reactors which need rapid temperature control. • Mass and heat transfer at the outer surface of helical coils was studied experimentally. • The experiments were conducted under gas sparing, single and two phase flow. • Variables were helical tube diameter, physical properties, and gas and liquid velocity. • Results verification in terms of natural convection and surface renewal mechanism was explained. - Abstract: The mass transfer behavior of the outer surface of vertical helical coil was studied by the electrochemical technique under single phase flow, gas sparging and two phase flow. Variables studied were helical tube diameter, physical properties of the solution, solution velocity and superficial gas velocity. The mass transfer data were correlated by dimensionless equations. Mass transfer enhancement ratio in case of two phase flow ranged from 1.1 to 4.9 compared to single phase flow. Implication of the results for the design and operation of helical coil reactors used to conduct L–S exothermic diffusion controlled reactions which need rapid temperature control were outlined. In this case the inner coil surface will act as a cooler while the outer surface will act a reaction surface. Immobilized enzyme catalyzed biochemical reactions where heat sensitive materials may be involved represent an example for the reactions which can employ the helical coil reactor. Also the importance of the results in the design of and operation of diffusion controlled membrane processes which employ helical coil membrane was noted. In view of the analogy between heat and mass transfer the possibility of using the results in the design and operation of helical coil heat exchangers was highlighted.

Model to calculate mass flow rate and other quantities of two-phase flow in a pipe with a densitometer, a drag disk, and a turbine meter

International Nuclear Information System (INIS)

Aya, I.

1975-11-01

The proposed model was developed at ORNL to calculate mass flow rate and other quantities of two-phase flow in a pipe when the flow is dispersed with slip between the phases. The calculational model is based on assumptions concerning the characteristics of a turbine meter and a drag disk. The model should be validated with experimental data before being used in blowdown analysis. In order to compare dispersed flow and homogeneous flow, the ratio of readings from each flow regime for each device discussed is calculated for a given mass flow rate and steam quality. The sensitivity analysis shows that the calculated flow rate of a steam-water mixture (based on the measurements of a drag disk and a gamma densitometer in which the flow is assumed to be homogeneous even if there is some slip between phases) is very close to the real flow rate in the case of dispersed flow at a low quality. As the steam quality increases at a constant slip ratio, all models are prone to overestimate. At 20 percent quality the overestimates reach 8 percent in the proposed model, 15 percent in Rouhani's model, 38 percent in homogeneous model, and 75 percent in Popper's model

FIX-II/2032, BWR Pump Trip Experiment 2032, Simulation Mass Flow and Power Transients

International Nuclear Information System (INIS)

1988-01-01

1 - Description of test facility: In the FIX-II pump trip experiments, mass flow and power transients were simulated subsequent to a total loss of power to the recirculation pumps in an internal pump boiling water reactor. The aim was to determine the initial power limit to give dryout in the fuel bundle for the specified transient. In addition, the peak cladding temperature was measured and the rewetting was studied. 2 - Description of test: Pump trip experiment 2032 was a part of test group 2, i.e. the mass flow transient was to simulate the pump coast down with a pump inertia of 11.3 kg.m -2 . The initial power in the 36-rod bundle was 4.44 MW which gave dryout after 1.4 s from the start of the flow transient. A maximum rod cladding temperature of 457 degrees C was measured. Rewetting was obtained after 7.6 s. 3 - Experimental limitations or shortcomings: No ECCS injection systems

How fast can a black hole eat. [Equation stationary spherically symmetric solutions, Thompson scattering, mass flow

Energy Technology Data Exchange (ETDEWEB)

Kafka, P; Meszaros, P [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (Germany, F.R.)

1976-11-01

Stationary spherically symmetric solutions of the equations for accretion of large mass flows onto a black hole, including the interaction of matter and radiation due to Thomson scattering in diffusion approximation are constructed. The relevance of these solutions is discussed with respect to the question of whether the limitation of the luminosity (Eddington limit) also implies an upper bound to the possible rate of mass flow. The question remains open until all instabilities have been studied. At the moment a negative answer is favoured.

Open boundary condition, Wilson flow and the scalar glueball mass

International Nuclear Information System (INIS)

Chowdhury, Abhishek; Harindranath, A.; Maiti, Jyotirmoy

2014-01-01

A major problem with periodic boundary condition on the gauge fields used in current lattice gauge theory simulations is the trapping of topological charge in a particular sector as the continuum limit is approached. To overcome this problem open boundary condition in the temporal direction has been proposed recently. One may ask whether open boundary condition can reproduce the observables calculated with periodic boundary condition. In this work we find that the extracted lowest glueball mass using open and periodic boundary conditions at the same lattice volume and lattice spacing agree for the range of lattice scales explored in the range 3 GeV≤(1/a)≤5 GeV. The problem of trapping is overcome to a large extent with open boundary and we are able to extract the glueball mass at even larger lattice scale ≈ 5.7 GeV. To smoothen the gauge fields we have used recently proposed Wilson flow which, compared to HYP smearing, exhibits better systematics in the extraction of glueball mass. The extracted glueball mass shows remarkable insensitivity to the lattice spacings in the range explored in this work, 3 GeV≤(1/a)≤5.7 GeV.

Analysis of Petrol and Diesel Vapor Using Selective Ion Flow Tube/Mass Spectrometry

Czech Academy of Sciences Publication Activity Database

Ping, CH.; Weijun, Z.; Yaman, CH.; Španěl, Patrik; Smith, D.

2003-01-01

Roč. 5, - (2003), s. 548-551 ISSN 0253-3820 Institutional research plan: CEZ:AV0Z4040901 Keywords : selected ion flow tube/mass spectrometry * fuel vapor Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.224, year: 2003

Mass flow rate correlation for two-phase flow of R218 through a capillary tube

Czech Academy of Sciences Publication Activity Database

Vinš, Václav; Vacek, V.

2009-01-01

Roč. 29, 14-15 (2009), s. 2816-2823 ISSN 1359-4311 Institutional research plan: CEZ:AV0Z20760514 Keywords : artificial neural network * capillary tube * mass flow rate correlation * R218 Subject RIV: BK - Fluid Dynamics Impact factor: 1.922, year: 2009 http://www.sciencedirect.com/science?_ob=PublicationURL&_cdi=5687&_pubType=J&_acct=C000034318&_version=1&_urlVersion=0&_userid=640952&md5=fc314a471a010545ee185394a6c8f5f7&jchunk=29#29

Time averaging procedure for calculating the mass and energy transfer rates in adiabatic two phase flow

International Nuclear Information System (INIS)

Boccaccini, L.V.

1986-07-01

To take advantages of the semi-implicit computer models - to solve the two phase flow differential system - a proper averaging procedure is also needed for the source terms. In fact, in some cases, the correlations normally used for the source terms - not time averaged - fail using the theoretical time step that arises from the linear stability analysis used on the right handside. Such a time averaging procedure is developed with reference to the bubbly flow regime. Moreover, the concept of mass that must be exchanged to reach equilibrium from a non-equilibrium state is introduced to limit the mass transfer during a time step. Finally some practical calculations are performed to compare the different correlations for the average mass transfer rate developed in this work. (orig.) [de

Acceleration of Gas Flow Simulations in Dual-Continuum Porous Media Based on the Mass-Conservation POD Method

KAUST Repository

Wang, Yi

2017-09-12

Reduced-order modeling approaches for gas flow in dual-porosity dual-permeability porous media are studied based on the proper orthogonal decomposition (POD) method combined with Galerkin projection. The typical modeling approach for non-porous-medium liquid flow problems is not appropriate for this compressible gas flow in a dual-continuum porous media. The reason is that non-zero mass transfer for the dual-continuum system can be generated artificially via the typical POD projection, violating the mass-conservation nature and causing the failure of the POD modeling. A new POD modeling approach is proposed considering the mass conservation of the whole matrix fracture system. Computation can be accelerated as much as 720 times with high precision (reconstruction errors as slow as 7.69 × 10−4%~3.87% for the matrix and 8.27 × 10−4%~2.84% for the fracture).

Acceleration of Gas Flow Simulations in Dual-Continuum Porous Media Based on the Mass-Conservation POD Method

KAUST Repository

Wang, Yi; Sun, Shuyu; Yu, Bo

2017-01-01

Reduced-order modeling approaches for gas flow in dual-porosity dual-permeability porous media are studied based on the proper orthogonal decomposition (POD) method combined with Galerkin projection. The typical modeling approach for non-porous-medium liquid flow problems is not appropriate for this compressible gas flow in a dual-continuum porous media. The reason is that non-zero mass transfer for the dual-continuum system can be generated artificially via the typical POD projection, violating the mass-conservation nature and causing the failure of the POD modeling. A new POD modeling approach is proposed considering the mass conservation of the whole matrix fracture system. Computation can be accelerated as much as 720 times with high precision (reconstruction errors as slow as 7.69 × 10−4%~3.87% for the matrix and 8.27 × 10−4%~2.84% for the fracture).

Technical characterization of dialysis fluid flow and mass transfer rate in dialyzers with various filtration coefficients using dimensionless correlation equation.

Science.gov (United States)

Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka

2017-06-01

The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B 12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D ) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.

Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

NARCIS (Netherlands)

Helsper, J.P.F.G.; Peters, R.J.B.; Bemmel, M.E.M. van; Rivera, Z.E.H.; Wagner, S.; Kammer, F. von der; Tromp, P.C.; Hofmann, T.; Weigel, S.

2016-01-01

Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry

Conventional-Flow Liquid Chromatography-Mass Spectrometry for Exploratory Bottom-Up Proteomic Analyses.

Science.gov (United States)

Lenčo, Juraj; Vajrychová, Marie; Pimková, Kristýna; Prokšová, Magdaléna; Benková, Markéta; Klimentová, Jana; Tambor, Vojtěch; Soukup, Ondřej

2018-04-17

Due to its sensitivity and productivity, bottom-up proteomics based on liquid chromatography-mass spectrometry (LC-MS) has become the core approach in the field. The de facto standard LC-MS platform for proteomics operates at sub-μL/min flow rates, and nanospray is required for efficiently introducing peptides into a mass spectrometer. Although this is almost a "dogma", this view is being reconsidered in light of developments in highly efficient chromatographic columns, and especially with the introduction of exceptionally sensitive MS instruments. Although conventional-flow LC-MS platforms have recently penetrated targeted proteomics successfully, their possibilities in discovery-oriented proteomics have not yet been thoroughly explored. Our objective was to determine what are the extra costs and what optimization and adjustments to a conventional-flow LC-MS system must be undertaken to identify a comparable number of proteins as can be identified on a nanoLC-MS system. We demonstrate that the amount of a complex tryptic digest needed for comparable proteome coverage can be roughly 5-fold greater, providing the column dimensions are properly chosen, extra-column peak dispersion is minimized, column temperature and flow rate are set to levels appropriate for peptide separation, and the composition of mobile phases is fine-tuned. Indeed, we identified 2 835 proteins from 2 μg of HeLa cells tryptic digest separated during a 60 min gradient at 68 μL/min on a 1.0 mm × 250 mm column held at 55 °C and using an aqua-acetonitrile mobile phases containing 0.1% formic acid, 0.4% acetic acid, and 3% dimethyl sulfoxide. Our results document that conventional-flow LC-MS is an attractive alternative for bottom-up exploratory proteomics.

Continuous-flow accelerator mass spectrometry for radiocarbon analysis

International Nuclear Information System (INIS)

Wills, J.S.C.; Han, B.X.; Von Reden, K.F.; Schneider, R.J.; Roberts, M.L.

2006-01-01

Accelerator Mass Spectrometry (AMS) is a widely used technique for radiocarbon dating of archaeological or environmental samples that are very small or very old (up to 50,000 years before present). Because of the method's extreme sensitivity, AMS can also serve as an environmental tracer and supplements conventional nuclear counting techniques for monitoring 14 C emissions from operating nuclear power plants and waste repositories. The utility of present AMS systems is limited by the complex sample preparation process required. Carbon from combusted artefacts must be incorporated into a solid metallic target from which a negative ion beam is produced and accelerated to MeV energies by an accelerator for subsequent analysis. This paper will describe a novel technique being developed by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Laboratory at the Woods Hole Oceanographic Institution for the production of negative carbon ion beams directly from a continuously flowing sample gas stream, eliminating the requirement for a solid target. A key component of the new technique is a microwave-driven, gaseous-feed ion source originally developed at Chalk River Laboratories for the very different requirements of a high current proton linear accelerator. A version of this ion source is now being adapted to serve as an injector for a dedicated AMS accelerator facility at NOSAMS. The paper begins with a review of the fundamentals of radiocarbon dating. Experiments carried out at NOSAMS with a prototype of the microwave ion source are described, including measurements of sample utilization efficiency and sample 'memory' effect. A new version of the microwave ion source, optimized for AMS, is also described. The report concludes with some predictions of new research opportunities that will become accessible to the technique of continuous-flow AMS. (author)

Continuous-flow accelerator mass spectrometry for radiocarbon analysis

International Nuclear Information System (INIS)

Wills, J.S.C.; Han, B.X.; Von Reden, K.F.; Schneider, R.J.; Roberts, M.L.

2006-05-01

Accelerator Mass Spectrometry (AMS) is a widely used technique for radiocarbon dating of archaeological or environmental samples that are very small or very old (up to 50,000 years before present). Because of the method's extreme sensitivity, AMS can also serve as an environmental tracer and supplements conventional nuclear counting techniques for monitoring 14 C emissions from operating nuclear power plants and waste repositories. The utility of present AMS systems is limited by the complex sample preparation process required. Carbon from combusted artefacts must be incorporated into a solid metallic target from which a negative ion beam is produced and accelerated to MeV energies by an accelerator for subsequent analysis. This paper will describe a novel technique being developed by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Laboratory at the Woods Hole Oceanographic Institution for the production of negative carbon ion beams directly from a continuously flowing sample gas stream, eliminating the requirement for a solid target. A key component of the new technique is a microwave-driven, gaseous-feed ion source originally developed at Chalk River Laboratories for the very different requirements of a high current proton linear accelerator. A version of this ion source is now being adapted to serve as an injector for a dedicated AMS accelerator facility at NOSAMS. The paper begins with a review of the fundamentals of radiocarbon dating. Experiments carried out at NOSAMS with a prototype of the microwave ion source are described, including measurements of sample utilization efficiency and sample 'memory' effect. A new version of the microwave ion source, optimized for AMS, is also described. The report concludes with some predictions of new research opportunities that will become accessible to the technique of continuous-flow AMS. (author)

Mass-corrections for the conservative coupling of flow and transport on collocated meshes

Energy Technology Data Exchange (ETDEWEB)

Waluga, Christian, E-mail: waluga@ma.tum.de [Institute for Numerical Mathematics (M2), Technische Universität München, Boltzmannstraße 3, D-85748 Garching bei München (Germany); Wohlmuth, Barbara [Institute for Numerical Mathematics (M2), Technische Universität München, Boltzmannstraße 3, D-85748 Garching bei München (Germany); Rüde, Ulrich [Department of Computer Science 10, University Erlangen–Nuremberg, Cauerstr. 11, D-91058 Erlangen (Germany)

2016-01-15

Buoyancy-driven flow models demand a careful treatment of the mass-balance equation to avoid spurious source and sink terms in the non-linear coupling between flow and transport. In the context of finite-elements, it is therefore commonly proposed to employ sufficiently rich pressure spaces, containing piecewise constant shape functions to obtain local or even strong mass-conservation. In three-dimensional computations, this usually requires nonconforming approaches, special meshes or higher order velocities, which make these schemes prohibitively expensive for some applications and complicate the implementation into legacy code. In this paper, we therefore propose a lean and conservatively coupled scheme based on standard stabilized linear equal-order finite elements for the Stokes part and vertex-centered finite volumes for the energy equation. We show that in a weak mass-balance it is possible to recover exact conservation properties by a local flux-correction which can be computed efficiently on the control volume boundaries of the transport mesh. We discuss implementation aspects and demonstrate the effectiveness of the flux-correction by different two- and three-dimensional examples which are motivated by geophysical applications.

31 CFR 800.217 - Hold.

Science.gov (United States)

2010-07-01

... and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF INVESTMENT... FOREIGN PERSONS Definitions § 800.217 Hold. The terms hold(s) and holding mean legal or beneficial ownership, whether direct or indirect, whether through fiduciaries, agents, or other means. ...

Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

NARCIS (Netherlands)

Helsper, Hans; Peters, Ruud J.B.; Bemmel, van Greet; Herrera Rivera, Zahira; Wagner, Stephan; Kammer, von der Frank; Tromp, Peter C.; Hofmann, Thilo; Weigel, Stefan

2016-01-01

Seven commercial titanium dioxide pigments and two other well-defined TiO₂ materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass

A study on mechanical properties and flow-induced vibrations of coil-shaped holddown spring

International Nuclear Information System (INIS)

Kim, Kyu-Tae

2010-01-01

The fuel assemblies used in the OPR1000s in Korea employ four coil-shaped hold-down springs to exert compressive load at the top of fuel assembly so that the assemblies may not be damaged by preventing its hydraulic-induced lifting-off from its lower seating surface. However, the coolant flow generates the flow-induced vibration at the coil-shaped hold-down springs which may cause wear on the spring surfaces. A hold-own spring may be fractured if torsional stress acting on its worn area exceeds a stress limit, resulting in the loss of hold-down spring force of the fuel assembly. In this paper, flow-induced vibration tests were performed for standard and improved coil type hold-down springs to investigate the effects of these two hold-down spring designs on flow-induced vibration wear. In parallel, a wide spectrum of mechanical tests was performed to obtain vibration-related characteristics of these two hold-down springs, which can be used as input data for the fuel assembly static and dynamic analysis. It is found that the improved hold-down spring design is better against flow-induced vibration wear than the standard one. With the use of the three-dimensional Solidwork model, the stress-related design lifetime of the improved hold-down spring was estimated by extrapolating its wear data measured from the flow-induced vibration tests, which indicates that the improved HD spring design will maintain integrity during the fuel design lifetime in OPR1000s in Korea.

Heat and mass transfer in porous cavity: Assisting flow

Energy Technology Data Exchange (ETDEWEB)

Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)

2016-06-08

In this paper, investigation of heat and mass transfer in a porous cavity is carried out. The governing partial differential equations are non-dimensionalised and solved using finite element method. The left vertical surface of the cavity is maintained at constant temperature and concentration which are higher than the ambient temperature and concentration applied at right vertical surface. The top and bottom walls of the cavity are adiabatic. Heat transfer is assumed to take place by natural convection and radiation. The investigation is carried out for assisting flow when buoyancy and gravity force act in same direction.

Comprehensive theory of the Deans' switch as a variable flow splitter: fluid mechanics, mass balance, and system behavior.

Science.gov (United States)

Boeker, Peter; Leppert, Jan; Mysliwietz, Bodo; Lammers, Peter Schulze

2013-10-01

The Deans' switch is an effluent switching device based on controlling flows of carrier gas instead of mechanical valves in the analytical flow path. This technique offers high inertness and a wear-free operation. Recently new monolithic microfluidic devices have become available. In these devices the whole flow system is integrated into a small metal device with low thermal mass and leak-tight connections. In contrast to a mechanical valve-based system, a flow-controlled system is more difficult to calculate. Usually the Deans' switch is used to switch one inlet to one of two outlets, by means of two auxiliary flows. However, the Deans' switch can also be used to deliver the GC effluent with a specific split ratio to both outlets. The calculation of the split ratio of the inlet flow to the two outlets is challenging because of the asymmetries of the flow resistances. This is especially the case, if one of the outlets is a vacuum device, such as a mass spectrometer, and the other an atmospheric detector, e.g. a flame ionization detector (FID) or an olfactory (sniffing) port. The capillary flows in gas chromatography are calculated with the Hagen-Poiseuille equation of the laminar, isothermal and compressible flow in circular tubes. The flow resistances in the new microfluidic devices have to be calculated with the corresponding equation for rectangular cross-section microchannels. The Hagen-Poiseuille equation underestimates the flow to a vacuum outlet. A corrected equation originating from the theory of rarefied flows is presented. The calculation of pressures and flows of a Deans' switch based chromatographic system is done by the solution of mass balances. A specific challenge is the consideration of the antidiffusion resistor between the two auxiliary gas lines of the Deans' switch. A full solution for the calculation of the Deans' switch including this restrictor is presented. Results from validation measurements are in good accordance with the developed

Interacting effects of uniform flow, plane shear, and near-wall proximity on the heat and mass transfer of respiratory aerosols

Energy Technology Data Exchange (ETDEWEB)

Worth Longest, P. [Virginia Commonwealth University, Richmond, VA (United States). Dept. of Mechanical Engineering; Kleinstreuer, C. [North Carolina State University, Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering

2004-10-01

Individual and interacting effects of uniform flow, plane shear, and near-wall proximity on spherical droplet heat and mass transfer have been assessed for low Reynolds number conditions beyond the creeping flow regime. Validated resolved volume simulations were used to compute heat and mass transfer surface gradients of two-dimensional axisymmetric droplets and three-dimensional spherical droplets near planar wall boundaries for conditions consistent with inhalable aerosols (5 {<=} d {<=} 300 {mu}m) in the upper respiratory tract. Results indicate that planar shear significantly impacts droplet heat and mass transfer for shear-based Reynolds numbers greater than 1, which occur for near-wall respiratory aerosols with diameters in excess of 50 {mu}m. Wall proximity is shown to significantly enhance heat and mass transfer due to conduction and diffusion at separation distances less than five particle diameters and for small Reynolds numbers. For the Reynolds number conditions of interest, significant non-linear effects arise due to the concurrent interaction of uniform flow and shear such that linear superposition of Sherwood or Nusselt number terms is not allowable. Based on the validated numeric simulations, multivariable Sherwood and Nusselt number correlations are provided to account for individual flow characteristics and concurrent non-linear interactions of uniform flow, planar shear, and near-wall proximity. These heat and mass transfer correlations can be applied to effectively compute condensation and evaporation rates of potentially toxic or therapeutic aerosols in the upper respiratory tract, where non-uniform flow and wall proximity are expected to significantly affect droplet transport, deposition, and vapor formation. (author)

Heat and mass transfer of a fuel droplet evaporating in oscillatory flow

International Nuclear Information System (INIS)

Jangi, M.; Kobayashi, H.

2009-01-01

A numerical study of the heat and mass transfer from an evaporating fuel droplet in oscillatory flow was performed. The flow was assumed to be laminar and axisymmetric, and the droplet was assumed to maintain its spherical shape during its lifetime. Based on these assumptions, the conservation equations in a general curvilinear coordinate were solved numerically. The behaviors of droplet evaporation in the oscillatory flow were investigated by analyzing the effects of flow oscillation on the evaporation process of a n-heptane fuel droplet at high pressure. The response of the time history of the square of droplet diameter and space-averaged Nusselt numbers to the main flow oscillation were investigated in frequency band of 1-75 Hz with various oscillation amplitudes. Results showed that, depending on the frequency and amplitude of the oscillation, there are different modes of response of the evaporation process to the flow oscillation. One response mode is synchronous with the main flow oscillation, and thus the quasi-steady condition is attained. Another mode is asynchronous with the flow oscillation and is highly unsteady. As for the evaporation rate, however, in all conditions is more greatly enhanced in oscillatory flow than in quiescent air. To quantify the conditions of the transition from quasi-steady to unsteady, the response of the boundary layer around the droplet surface to the flow oscillation was investigated. The results led to including the oscillation Strouhal number as a criteria for the transition. The numerical results showed that at a low Strouhal number, a quasi-steady boundary layer is formed in response to the flow oscillation, whereas by increasing the oscillation Strouhal number, the phenomena become unsteady.

零净质量射流的数值模拟%Numerical simulation of the zero mass jet flow

Institute of Scientific and Technical Information of China (English)

石清; 李桦

2011-01-01

对零净质量射流致动器的流场和有零净质量射流时翼型的绕流流场进行了数值模拟,分析了动网格与几何守恒率、边界条件、湍流模型对零净质量射流致动器流场计算的影响,分析了零净质量射流的速度幅值和驱动频率对翼型增升效果的影响.研究结果表明,在复杂计算中可以对能动部件的边界作赋值处理;随着射流速度幅值的增加,翼型的平均升力系数和阻力系数都要增加;射流频率对升力的影响呈非线性.%Numerical simulation methods are used to investigate the actuator of zero mass jet flow and the flow around airfoil with zero mass jet flow.The effects on the actuator of zero mass jet flow are analysed about dynamic grid,geometry conservation law, numerical boundary conditions, and turbulence mode.And the effects on increasing lift are analysed also, including the jet flow velocity and frequency.The results indicate that numerical boundary conditions of the actuator of zero mass jet flow can be treated with given numerical value for complicated calculation, both the average lift coefficient and the average drag coefficient are added with the increase of the jet flow velocity, and the effects of the jet flow frequency on lift are non - linear.

Vibration isolation by compliant sensor mounting applied to a coriolis mass-flow meter

NARCIS (Netherlands)

van de Ridder, Bert; Hakvoort, Wouter; van Dijk, Johannes

2014-01-01

In this paper a vibration isolated design of the Coriolis Mass-Flow Meter (CMFM) is proposed, by introducing a compliant connection between the casing and the tube displacement sensors with the intention to obtain a relative displacement measurement of the fluid conveying tube, dependent on the tube

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

Directory of Open Access Journals (Sweden)

Jian Li

2015-12-01

Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

Mass and energy flows between the Solar chromosphere, transition region, and corona

Science.gov (United States)

Hansteen, V. H.

2017-12-01

A number of increasingly sophisticated numerical simulations spanning the convection zone to corona have shed considerable insight into the role of the magnetic field in the structure and energetics of the Sun's outer atmosphere. This development is strengthened by the wealth of observational data now coming on-line from both ground based and space borne observatories. We discuss what numerical models can tell us about the mass and energy flows in the region of the upper chromosphere and lower corona, using a variety of tools, including the direct comparison with data and the use of passive tracer particles (so-called 'corks') inserted into the simulated flows.

Investigation of technology for monitoring UF6 mass flow

International Nuclear Information System (INIS)

Cooley, J.N.; Moran, B.W.; Swindle, D.W. Jr.

1987-06-01

The applicability of gas flow meters, in-line enrichment monitors, and instruments for measuring uranium or UF 6 concentrations in process streams as a means for verifying declared plant throughput have been investigated. The study was performed to assist the International Atomic Energy Agency in the development of an effective international safeguards approach for aerodynamic uranium enrichment plants. Because the process gas in an aerodynamic enrichment facility is a mixture of UF 6 and H 2 , a mass flow measurement in conjunction with a measurement of the uranium (or UF 6 ) concentration in the process gas is required to quantify the amount of uranium being fed into, and withdrawn from, the cascades for nuclear materials accountability verification. In-line enrichment monitors developed for the US gas centrifuge enrichment plant are found to be applicable only to pure UF 6 streams. Of the five gas flow meters evaluated, the orifice meter and the pitot tube meter are judged the best choices for the proposed applications: the first is recommended for low-velocity gas, small diameter piping; the latter, for high-velocity gas, large diameter piping. Of the six procedures evaluated for measurement of uranium or UF 6 concentration in a mixed process stream, infrared-ultraviolet-visible spectrophotometry is judged to be the best procedure currently available to perform the required measurement. 4 refs., 3 figs., 3 tabs

A mass and momentum conserving unsplit semi-Lagrangian framework for simulating multiphase flows

Energy Technology Data Exchange (ETDEWEB)

Owkes, Mark, E-mail: mark.owkes@montana.edu [Mechanical and Industrial Engineering, Montana State University, Bozeman, MT 59717 (United States); Desjardins, Olivier [Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 (United States)

2017-03-01

In this work, we present a computational methodology for convection and advection that handles discontinuities with second order accuracy and maintains conservation to machine precision. This method can transport a variety of discontinuous quantities and is used in the context of an incompressible gas–liquid flow to transport the phase interface, momentum, and scalars. The proposed method provides a modification to the three-dimensional, unsplit, second-order semi-Lagrangian flux method of Owkes & Desjardins (JCP, 2014). The modification adds a refined grid that provides consistent fluxes of mass and momentum defined on a staggered grid and discrete conservation of mass and momentum, even for flows with large density ratios. Additionally, the refined grid doubles the resolution of the interface without significantly increasing the computational cost over previous non-conservative schemes. This is possible due to a novel partitioning of the semi-Lagrangian fluxes into a small number of simplices. The proposed scheme is tested using canonical verification tests, rising bubbles, and an atomizing liquid jet.

Microplasma-based flowing atmospheric-pressure afterglow (FAPA) source for ambient desorption-ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zeiri, Offer M.; Storey, Andrew P.; Ray, Steven J., E-mail: sjray2@buffalo.edu; Hieftje, Gary M.

2017-02-01

A new direct-current microplasma-based flowing atmospheric pressure afterglow (FAPA) source was developed for use in ambient desorption-ionization mass spectrometry. The annular-shaped microplasma is formed in helium between two concentric stainless-steel capillaries that are separated by an alumina tube. Current-voltage characterization of the source shows that this version of the FAPA operates in the normal glow-discharge regime. A glass surface placed in the path of the helium afterglow reaches temperatures of up to approximately 400 °C; the temperature varies with distance from the source and helium flow rate through the source. Solid, liquid, and vapor samples were examined by means of a time-of-flight mass spectrometer. Results suggest that ionization occurs mainly through protonation, with only a small amount of fragmentation and adduct formation. The mass range of the source was shown to extend up to at least m/z 2722 for singly charged species. Limits of detection for several small organic molecules were in the sub-picomole range. Examination of competitive ionization revealed that signal suppression occurs only at high (mM) concentrations of competing substances. - Highlights: • The first microplasma version of the FAPA source. • Current-voltage behavior reflects the behavior of a normal glow discharge. • Detection limits below 1 pmol for the classes of organic compounds studied over a wide mass range. • Mass spectra show limited fragmentation.

The determinants of corporate cash holdings: An empirical investigation of the industry effect of UK publicly held firms (1998-2013)

OpenAIRE

WANG, ZIWEN

2015-01-01

Abstract This paper investigates the determinants of cash holdings by publicly traded firms over the period 1998-2013. The results suggest that cash holdings are positively affected by investment opportunity set, capital expenditure and profitability and negatively affected by the real firm size, liquid assets substitutes, leverage level, cash flow and dividend payments, which are generally in line with previous studies. In addition, we observed the change of corporate cash holdings during...

Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans

DEFF Research Database (Denmark)

Kjeld, Thomas; Pott, Frank C; Secher, Niels H

2009-01-01

perfusion evaluated as the middle cerebral artery mean flow velocity (MCA V(mean)) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (Pa(CO(2))) from 4.2 to 6.7 kPa and MCA V(mean) from 37 to 103 cm/s (mean; approximately 178%; P...... breath hold increased Pa(CO(2)) from 5.9 to 8.2 kPa (P ... 180-W exercise (from 47 to 53 cm/s), and this increment became larger with facial immersion (76 cm/s, approximately 62%; P breath hold diverts blood toward the brain with a >100% increase in MCA V(mean), largely...

Effects of heat and mass transfer on unsteady boundary layer flow of a chemical reacting Casson fluid

Science.gov (United States)

Khan, Kashif Ali; Butt, Asma Rashid; Raza, Nauman

2018-03-01

In this study, an endeavor is to observe the unsteady two-dimensional boundary layer flow with heat and mass transfer behavior of Casson fluid past a stretching sheet in presence of wall mass transfer by ignoring the effects of viscous dissipation. Chemical reaction of linear order is also invoked here. Similarity transformation have been applied to reduce the governing equations of momentum, energy and mass into non-linear ordinary differential equations; then Homotopy analysis method (HAM) is applied to solve these equations. Numerical work is done carefully with a well-known software MATHEMATICA for the examination of non-dimensional velocity, temperature, and concentration profiles, and then results are presented graphically. The skin friction (viscous drag), local Nusselt number (rate of heat transfer) and Sherwood number (rate of mass transfer) are discussed and presented in tabular form for several factors which are monitoring the flow model.

Air mass flow estimation in turbocharged diesel engines from in-cylinder pressure measurement

Energy Technology Data Exchange (ETDEWEB)

Desantes, J.M.; Galindo, J.; Guardiola, C.; Dolz, V. [CMT - Motores Termicos, Universidad Politecnica de Valencia (Spain)

2010-01-15

Air mass flow determination is needed for the control of current internal combustion engines. Current methods are based on specific sensors (as hot wire anemometers) or indirect estimation through manifold pressure. With the availability of cylinder pressure sensors for engine control, methods based on them can be used for replacing or complementing standard methods. Present paper uses in cylinder pressure increase during the intake stroke for inferring the trapped air mass. The method is validated on two different turbocharged diesel engines and compared with the standard methods. (author)

On the features, successes and challenges of selected ion flow tube mass spectrometry

Czech Academy of Sciences Publication Activity Database

Španěl, Patrik; Smith, D.

2013-01-01

Roč. 19, č. 4 (2013), s. 225-246 ISSN 1469-0667 R&D Projects: GA ČR GA13-28882S Institutional support: RVO:61388955 Keywords : selected ion flow tube mass spectrometry * SIFT-MS * breath metabolies Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.165, year: 2013

Joint test rig for tests and calibration of different methods of two-phase mass flow measurement

International Nuclear Information System (INIS)

John, H.; Erbacher, F.; Wanner, E.

1975-01-01

On behalf of the Federal Ministry of Research and Technology, the Institute of Reactor Components (IRB) has begun building a test rig which will be used for testing and calibrating the methods of measuring non-steady state two-phase mass flows developed by various research agencies. The test rig is designed for the generation of steam-water mixtures of any mixing ratio and a maximum pressure of 160 data. Depending on the mixing ratio, the mass flow will reach a maximum level of 10 to 20 t/h. The conceptual design phase of the test rig has largely been finished, the component ordering phase has begun. (orig.) [de

Semi-analytical treatment of fracture/matrix flow in a dual-porosity simulator for unsaturated fractured rock masses

International Nuclear Information System (INIS)

Zimmerman, R.W.; Bodvarsson, G.S.

1992-04-01

A semi-analytical dual-porosity simulator for unsaturated flow in fractured rock masses has been developed. Fluid flow between the fracture network and the matrix blocks is described by analytical expressions that have been derived from approximate solutions to the imbibition equation. These expressions have been programmed into the unsaturated flow simulator, TOUGH, as a source/sink term. Flow processes are then simulated using only fracture elements in the computational grid. The modified code is used to simulate flow along single fractures, and infiltration into pervasively fractured formations

Characterization of the fracturation of rock masses for determining flow

International Nuclear Information System (INIS)

Derlich, S.

1984-02-01

Flow in a rock mass is the consequence of the permeability of the rock, which can be roughly separated into matrix permeability and fissure permeability. In crystalline rocks fissure permeability is dominant, especially where the rocks are extensively fractured. It is thus essential, by means of studies either at the surface or underground, to characterize the volume fracturation in the mass considered. The purpose of this paper is to illustrate the methodology for analysing fracturation at a site by the studies performed on the granite mass of Auriat in the French Massif Central. A number of geology laboratories have participated in this study and a broad spectrum of observations has been made which can be used for determining the various stages of a study with a view to selection of a site, the advantages and limitations of each method or study plan and additional methods which need to be used for gaining as complete a picture as possible of the fracturation. A brief examination of the results obtained at Auriat enables the relative advantages of using these various methods at a particular site to be compared

Determination of mass flow rate and quality distributions between the subchannels of a heated bundle. [BWR; PWR

Energy Technology Data Exchange (ETDEWEB)

Bayoumi, M.; Charlot, R.; Ricque, R.

1976-05-01

For analyzing, correlating and extrapolating experimental burn-out results obtained with LWR rod bundles, it is necessary to know the distributions of mass flow rate and quality between the subchannels. A description is presented of an experimental study in progress at the CEN-Grenoble for determining and adjusting the laws of mixing in the FLICA Code which is used to predict these distributions. The experiments are performed on the FRENESIE loop with Freon 12. The test section, in vertical position, consists of a four rod bundle in a channel with square section. The heat flux is axially uniform. The flow of each subchannel can be sampled in ''isokinetic conditions,'' at the end of the heating length. Thermodynamic quality and mass flow rate of the samplings are measured in steady state conditions by using respectively a calorimeter and a turbine flow meter. The test facility is described and experimental data are presented and discussed.

Interaction of mass-loaded solar wind flow with blunt body

International Nuclear Information System (INIS)

Breus, T.K.; Krymskii, A.M.; Mitnitskii, V.Ya.

1987-01-01

The aim of this paper is the numerical modeling of the solar wind interaction with Venus taking into account the mass loading effect due to the photoionization of the Venus neutral oxygen corona. The analysis has shown that this effect unambiguously explains the number of peculiarities of the SW-Venus interaction pattern that could not be quantitatively explained before, namely the shock front position, and the characteristics of the SW flow and magnetic field in the Venus ionosheath observed from experiments onboard of Venera-9 and -10 and Pioneer-Venus spacecraft. (author)

Source Distribution Method for Unsteady One-Dimensional Flows With Small Mass, Momentum, and Heat Addition and Small Area Variation

Science.gov (United States)

Mirels, Harold

1959-01-01

A source distribution method is presented for obtaining flow perturbations due to small unsteady area variations, mass, momentum, and heat additions in a basic uniform (or piecewise uniform) one-dimensional flow. First, the perturbations due to an elemental area variation, mass, momentum, and heat addition are found. The general solution is then represented by a spatial and temporal distribution of these elemental (source) solutions. Emphasis is placed on discussing the physical nature of the flow phenomena. The method is illustrated by several examples. These include the determination of perturbations in basic flows consisting of (1) a shock propagating through a nonuniform tube, (2) a constant-velocity piston driving a shock, (3) ideal shock-tube flows, and (4) deflagrations initiated at a closed end. The method is particularly applicable for finding the perturbations due to relatively thin wall boundary layers.

Lagrangian mass-flow investigations of inorganic contaminants in wastewater-impacted streams

Science.gov (United States)

Barber, L.B.; Antweiler, Ronald C.; Flynn, J.L.; Keefe, S.H.; Kolpin, D.W.; Roth, D.A.; Schnoebelen, D.J.; Taylor, Howard E.; Verplanck, P.L.

2011-01-01

Understanding the potential effects of increased reliance on wastewater treatment plant (WWTP) effluents to meet municipal, agricultural, and environmental flow requires an understanding of the complex chemical loading characteristics of the WWTPs and the assimilative capacity of receiving waters. Stream ecosystem effects are linked to proportions of WWTP effluent under low-flow conditions as well as the nature of the effluent chemical mixtures. This study quantifies the loading of 58 inorganic constituents (nutrients to rare earth elements) from WWTP discharges relative to upstream landscape-based sources. Stream assimilation capacity was evaluated by Lagrangian sampling, using flow velocities determined from tracer experiments to track the same parcel of water as it moved downstream. Boulder Creek, Colorado and Fourmile Creek, Iowa, representing two different geologic and hydrologic landscapes, were sampled under low-flow conditions in the summer and spring. One-half of the constituents had greater loads from the WWTP effluents than the upstream drainages, and once introduced into the streams, dilution was the predominant assimilation mechanism. Only ammonium and bismuth had significant decreases in mass load downstream from the WWTPs during all samplings. The link between hydrology and water chemistry inherent in Lagrangian sampling allows quantitative assessment of chemical fate across different landscapes. ?? 2011 American Chemical Society.

Investigating the limitations of single breath-hold renal artery blood flow measurements using spiral phase contrast MR with R-R interval averaging.

Science.gov (United States)

Steeden, Jennifer A; Muthurangu, Vivek

2015-04-01

1) To validate an R-R interval averaged golden angle spiral phase contrast magnetic resonance (RAGS PCMR) sequence against conventional cine PCMR for assessment of renal blood flow (RBF) in normal volunteers; and 2) To investigate the effects of motion and heart rate on the accuracy of flow measurements using an in silico simulation. In 20 healthy volunteers RAGS (∼6 sec breath-hold) and respiratory-navigated cine (∼5 min) PCMR were performed in both renal arteries to assess RBF. A simulation of RAGS PCMR was used to assess the effect of heart rate (30-105 bpm), vessel expandability (0-150%) and translational motion (x1.0-4.0) on the accuracy of RBF measurements. There was good agreement between RAGS and cine PCMR in the volunteer study (bias: 0.01 L/min, limits of agreement: -0.04 to +0.06 L/min, P = 0.0001). The simulation demonstrated a positive linear relationship between heart rate and error (r = 0.9894, P 100 bpm), or when there is significant motion (vessel expandability: >80%, vessel translation: >x2.2). © 2014 Wiley Periodicals, Inc.

Fiber Optic Mass Flow Gauge for Liquid Cryogenic Fuel Facilities Monitoring and Control, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR Phase I proposal describes a fiber optic mass flow gauge that will aid in managing liquid hydrogen and oxygen fuel storage and transport. The increasing...

78 FR 23162 - Supervision and Regulation Assessments for Bank Holding Companies and Savings and Loan Holding...

Science.gov (United States)

2013-04-18

... bank holding company's Consolidated Financial Statements for Bank Holding Companies (FR Y-9C) forms; \\3... Balance Sheet of the BHC's Consolidated Financial Statements for Bank Holding Companies (FR Y-9C) (OMB No... holding companies with $50 billion or more in total consolidated assets, and nonbank financial companies...

Virtual Refrigerant Mass Flow and Power Sensors for Variable-Speed Compressors

OpenAIRE

Kim, Woohyun; Braun, James E.

2012-01-01

The use of variable-speed compressors in heat pumps and air conditioners has increased in recent years in order to improve comfort and energy efficiency. At the same time, there is a trend towards embedding more sensors in this type of equipment to facilitate real-time energy monitoring and diagnostics. Although compressor mass flow rate and power consumption are useful indices for performance monitoring and diagnostics, they are expensive to measure. The virtual variable-speed compressor sen...

Mechanisms of flow and water mass variability in Denmark Strait

Science.gov (United States)

Moritz, Martin; Jochumsen, Kerstin; Quadfasel, Detlef; Mashayekh Poul, Hossein; Käse, Rolf H.

2017-04-01

The dense water export through Denmark Strait contributes significantly to the lower limb of the Atlantic Meridional Overturning Circulation. Overflow water is transported southwestward not only in the deep channel of the Strait, but also within a thin bottom layer on the Greenland shelf. The flow on the shelf is mainly weak and barotropic, exhibiting many recirculations, but may eventually contribute to the overflow layer in the Irminger Basin by spilling events in the northern Irminger Basin. Especially the circulation around Dohrn Bank and the Kangerdlussuaq Trough contribute to the shelf-basin exchange. Moored observations show the overflow in Denmark Strait to be stable during the last 20 years (1996-2016). Nevertheless, flow variability was noticed on time scales of eddies and beyond, i.e. on weekly and interannual scales. Here, we use a combination of mooring data and shipboard hydrographic and current data to address the dominant modes of variability in the overflow, which are (i) eddies, (ii) barotropic pulsations of the plume, (iii) lateral shifts of the plume core position, and (iv) variations in vertical extension, i.e. varying overflow thickness. A principle component analysis is carried out and related to variations in sea surface height and wind stress, derived from satellite measurements. Furthermore, a test for topographic waves is performed. Shelf contributions to the overflow core in the Irminger Basin are identified from measurements of temperature and salinity, as well as velocity, which were obtained during recent cruises in the region. The flow and water mass pattern obtained from the observational data is compared to simulations in a high resolution regional model (ROMS), where tracer release experiments and float deployments were carried out. The modelling results allow a separation between different atmospheric forcing modes (NAO+ vs NAO- situations), which impact the water mass distribution and alter the dense water pathways on the

Heat and mass transfer from the mantle: heat flow and He-isotope constraints

Directory of Open Access Journals (Sweden)

B. G. Polyak

2005-06-01

Full Text Available Terrestrial heat flow density, q, is inversely correlated with the age, t, of tectono-magmatic activity in the Earth's crust (Polyak and Smirnov, 1966; etc.. «Heat flow-age dependence» indicates unknown temporal heat sources in the interior considered a priori as the mantle-derived diapirs. The validity of this hypothesis is demonstrated by studying the helium isotope ratio, 3He/4He = R, in subsurface fluids. This study discovered the positive correlation between the regionally averaged (background estimations of R- and q-values (Polyak et al., 1979a. Such a correlation manifests itself in both pan-regional scales (Norhtern Eurasia and separate regions, e.g., Japan (Sano et al., 1982, Eger Graben (Polyak et al., 1985 Eastern China rifts (Du, 1992, Southern Italy (Italiano et al., 2000, and elsewhere. The R-q relation indicates a coupled heat and mass transfer from the mantle into the crust. From considerations of heat-mass budget this transfer can be provided by the flux consisting of silicate matter rather than He or other volatiles. This conclusion is confirmed by the correlation between 3He/ 4He and 87Sr/86Sr ratios in the products of the volcanic and hydrothermal activity in Italy (Polyak et al., 1979b; Parello et al., 2000 and other places. Migration of any substance through geotemperature field transports thermal energy accumulated within this substance, i.e. represents heat and mass transfer. Therefore, only the coupled analysis of both material and energy aspects of this transfer makes it possible to characterise the process adequately and to decipher an origin of terrestrial heat flow observed in upper parts of the earth crust. An attempt of such kind is made in this paper.

Development of a locally mass flux conservative computer code for calculating 3-D viscous flow in turbomachines

Science.gov (United States)

Walitt, L.

1982-01-01

The VANS successive approximation numerical method was extended to the computation of three dimensional, viscous, transonic flows in turbomachines. A cross-sectional computer code, which conserves mass flux at each point of the cross-sectional surface of computation was developed. In the VANS numerical method, the cross-sectional computation follows a blade-to-blade calculation. Numerical calculations were made for an axial annular turbine cascade and a transonic, centrifugal impeller with splitter vanes. The subsonic turbine cascade computation was generated in blade-to-blade surface to evaluate the accuracy of the blade-to-blade mode of marching. Calculated blade pressures at the hub, mid, and tip radii of the cascade agreed with corresponding measurements. The transonic impeller computation was conducted to test the newly developed locally mass flux conservative cross-sectional computer code. Both blade-to-blade and cross sectional modes of calculation were implemented for this problem. A triplet point shock structure was computed in the inducer region of the impeller. In addition, time-averaged shroud static pressures generally agreed with measured shroud pressures. It is concluded that the blade-to-blade computation produces a useful engineering flow field in regions of subsonic relative flow; and cross-sectional computation, with a locally mass flux conservative continuity equation, is required to compute the shock waves in regions of supersonic relative flow.

A study of heat and mass transfer on magnetohydrodynamic (MHD flow of nanoparticles

Directory of Open Access Journals (Sweden)

Syed Tauseef Mohyud-Din

2018-03-01

Full Text Available Investigation of the flow, heat and mass transfer of a nanofluid over a suddenly moved flat plate is presented using Buongiorno's model. This study is different from some of the previous studies as the effects of Brownian motion and thermophoresis on nanoparticles volume fraction are passively controlled on the boundary rather than actively. The partial differential equations governing the flow are reduced to a system of nonlinear ordinary differential equations. Viable similarity transforms are used for this purpose. A well-known numerical scheme called Runge-Kutta-Fehlberg method coupled with shooting procedure has been used to find the solution of resulting system of equations. Discussions on the effects of different emerging parameters is provided using graphical aid. A table is also given that provides the results of different parameters on local Nusselt and Sherwood numbers. The passive control model can be used to control the boundary layer thickness as well as the rate of mass transfer at the wall. Keywords: Nanofluid, Brownian motion, Thermophoresis, Nusselt number, Sherwood number

12 CFR 584.2-2 - Permissible bank holding company activities of savings and loan holding companies.

Science.gov (United States)

2010-01-01

... savings and loan holding companies. 584.2-2 Section 584.2-2 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY SAVINGS AND LOAN HOLDING COMPANIES § 584.2-2 Permissible bank holding company activities of savings and loan holding companies. (a) General. For purposes of § 584.2(b)(6)(i) of this part...

Trickle-bed root culture bioreactor design and scale-up: growth, fluid-dynamics, and oxygen mass transfer.

Science.gov (United States)

Ramakrishnan, Divakar; Curtis, Wayne R

2004-10-20

Trickle-bed root culture reactors are shown to achieve tissue concentrations as high as 36 g DW/L (752 g FW/L) at a scale of 14 L. Root growth rate in a 1.6-L reactor configuration with improved operational conditions is shown to be indistinguishable from the laboratory-scale benchmark, the shaker flask (mu=0.33 day(-1)). These results demonstrate that trickle-bed reactor systems can sustain tissue concentrations, growth rates and volumetric biomass productivities substantially higher than other reported bioreactor configurations. Mass transfer and fluid dynamics are characterized in trickle-bed root reactors to identify appropriate operating conditions and scale-up criteria. Root tissue respiration goes through a minimum with increasing liquid flow, which is qualitatively consistent with traditional trickle-bed performance. However, liquid hold-up is much higher than traditional trickle-beds and alternative correlations based on liquid hold-up per unit tissue mass are required to account for large changes in biomass volume fraction. Bioreactor characterization is sufficient to carry out preliminary design calculations that indicate scale-up feasibility to at least 10,000 liters.

75 FR 27564 - Final Notice on Ending the “Hold-Harmless” Policy in Calculating Section 8 Income Limits Under...

Science.gov (United States)

2010-05-17

... face serious cash flow problems. Such a decrease in rental income would result in insufficient cash... funds will face serious cash flow issues if the hold-harmless policy is eliminated. These commenters... from Section 8 income limits, while well intentioned, would create a massive administrative problem...

Effect of virtual mass on the characteristics and the numerical stability in two-phase flows

International Nuclear Information System (INIS)

No, H.C.; Kazimi, M.S.

1981-04-01

It is known that the typical six equation two-fluid model of the two-phase flow possesses complex characteristics, exhibits unbounded instabilities in the short-wavelength limit and constitutes an ill-posed initial value problem. Among the suggestions to overcome these difficulties, one model for the virtual mass force terms were studied here, because the virtual mass represents real physical effects to accomplish the dissipation for numerical stability. It was found that the virtual mass has a profound effect upon the mathematical characteristic and numerical stability. Here a quantitative bound on the coefficient of the virtual mass terms was suggested for mathematical hyperbolicity and numerical stability. It was concluded that the finite difference scheme with the virtual mass model is restricted only by the convective stability conditions with the above suggested value

Three dimensional numerical investigation of flow mixing in curved tubes and mass transfer in T-channel junction

International Nuclear Information System (INIS)

Pandey, Pradeep; Nayak, A.K.; Vijayan, P.K.

2014-01-01

Three dimensional flow patterns appearing in geometries such as curved pipes and T-channel junctions have important applications and are attractive for research. Unlike the flow in a straight tube, fluid motion in a curved tube is not parallel to the axis of bend, owing to the presence of centrifugal effects. It is characterized by a secondary flow in a cross-sectional plane normal to the main flow. Consequently, secondary flow separation near the inner wall is observed in the developing region. The strength of the secondary flow is greatly influenced by the curvature ratio and in turn, a non-dimensional parameter called the Dean Number. Secondary flow increases flow resistance, resulting in a larger pressure drop along the bend. The location of the maximum axial velocity gets shifted towards the outer wall. Flow in a T-channel junction is also a configuration of great significance. The simulations of the present work show that flow at low Reynolds numbers (Re ≤ 115) is steady and symmetric. For low Reynolds numbers, flow in the downstream channel remains highly segregated about the centerline. The appearance of vortices in the T-channel junction does little to redistribute concentration when flow remains symmetric. With increasing Reynolds number, transition takes place towards asymmetric flow. The incoming flow field gets redistributed at the center-plane and the dividing streamline becomes increasingly distorted. The flow field is characterized by thin elongated fluid interfaces across which momentum diffusion takes place. Flow at higher Reynolds numbers (Re ≥ 250) becomes unsteady in which unstable stagnation stream traces move periodically leftward and rightward at top and bottom walls. Trajectories of mass-less particles show greater dwelling in the junction as compared to those of finite mass particle. The numerical simulation is carried out in the present work using ANUPRAVAHA, a general purpose CFD solver developed at IIT Kanpur in collaboration with

Predictions of the marviken subcooled critical mass flux using the critical flow scaling parameters

Energy Technology Data Exchange (ETDEWEB)

Park, Choon Kyung; Chun, Se Young; Cho, Seok; Yang, Sun Ku; Chung, Moon Ki [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1998-12-31

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling (C{sub d,ref} and {Delta}{Tau}{sup *} {sub sub}). The agreement between the measured data and the predictions are excellent. 8 refs., 8 figs. 1 tab. (Author)

Predictions of the marviken subcooled critical mass flux using the critical flow scaling parameters

Energy Technology Data Exchange (ETDEWEB)

Park, Choon Kyung; Chun, Se Young; Cho, Seok; Yang, Sun Ku; Chung, Moon Ki [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-12-31

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling (C{sub d,ref} and {Delta}{Tau}{sup *} {sub sub}). The agreement between the measured data and the predictions are excellent. 8 refs., 8 figs. 1 tab. (Author)

Continuous flow isotope ratio mass spectrometer (CF-IRMS) and its applications in hydrocarbon research and exploration

International Nuclear Information System (INIS)

Kalpana, G.; Patil, D.J.; Kumar, B.

2004-01-01

Stable isotope ratio mass spectrometers have been widely used to determine the isotopic ratios of light elements such as hydrogen, carbon, nitrogen, oxygen and sulphur. Continuous Flow Isotope Ratio Mass Spectrometry (CFIRMS) provides reliable data on nanomole amount of sample gas without the need for cryogenic trapping using cold fingers as in dual inlet isotope ratio mass spectrometer. High sample throughput is achieved as the system is configured with automated sample preparation devices and auto samplers. This paper presents a brief description of CFIRMS exploration

Mass-flux subgrid-scale parameterization in analogy with multi-component flows: a formulation towards scale independence

Directory of Open Access Journals (Sweden)

J.-I. Yano

2012-11-01

Full Text Available A generalized mass-flux formulation is presented, which no longer takes a limit of vanishing fractional areas for subgrid-scale components. The presented formulation is applicable to a~situation in which the scale separation is still satisfied, but fractional areas occupied by individual subgrid-scale components are no longer small. A self-consistent formulation is presented by generalizing the mass-flux formulation under the segmentally-constant approximation (SCA to the grid–scale variabilities. The present formulation is expected to alleviate problems arising from increasing resolutions of operational forecast models without invoking more extensive overhaul of parameterizations.

The present formulation leads to an analogy of the large-scale atmospheric flow with multi-component flows. This analogy allows a generality of including any subgrid-scale variability into the mass-flux parameterization under SCA. Those include stratiform clouds as well as cold pools in the boundary layer.

An important finding under the present formulation is that the subgrid-scale quantities are advected by the large-scale velocities characteristic of given subgrid-scale components (large-scale subcomponent flows, rather than by the total large-scale flows as simply defined by grid-box average. In this manner, each subgrid-scale component behaves as if like a component of multi-component flows. This formulation, as a result, ensures the lateral interaction of subgrid-scale variability crossing the grid boxes, which are missing in the current parameterizations based on vertical one-dimensional models, and leading to a reduction of the grid-size dependencies in its performance. It is shown that the large-scale subcomponent flows are driven by large-scale subcomponent pressure gradients. The formulation, as a result, furthermore includes a self-contained description of subgrid-scale momentum transport.

The main purpose of the present paper

FEFLOW finite element modeling of flow, mass and heat transport in porous and fractured media

CERN Document Server

Diersch, Hans-Jörg G

2013-01-01

Placing advanced theoretical and numerical methods in the hands of modeling practitioners and scientists, this book explores the FEFLOW system for solving flow, mass and heat transport processes in porous and fractured media. Offers applications and exercises.

Quantitative estimation of the influence of external vibrations on the measurement error of a coriolis mass-flow meter

NARCIS (Netherlands)

van de Ridder, Bert; Hakvoort, Wouter; van Dijk, Johannes; Lötters, Joost Conrad; de Boer, Andries; Dimitrovova, Z.; de Almeida, J.R.

2013-01-01

In this paper the quantitative influence of external vibrations on the measurement value of a Coriolis Mass-Flow Meter for low flows is investigated, with the eventual goal to reduce the influence of vibrations. Model results are compared with experimental results to improve the knowledge on how

Biogenic materials in Switzerland - mass and energy flows; Biogene Gueter in der Schweiz: Massen- und Energiefluesse

Energy Technology Data Exchange (ETDEWEB)

Scheurer, K.; Baier, U.

2001-07-01

This study supplements a series of studies carried out under the 'Energy 2000' programme and its follow-up 'SwissEnergy' on the energy potential of biomass in Switzerland. This study compiles data from existing studies and statistics and presents them as detailed mass and energy flow diagrams. The findings of the study confirm that the most important biomass fluxes are generated by animal feed stuffs and manure and that these represent an important potential for use as a source of energy. The authors state that in the foodstuffs and wood/paper industries a high level of sustainability in resource usage has been attained and that the largest losses in mass and energy flows can be found in livestock breeding and human biomass consumption.

Biogenic materials in Switzerland - mass and energy flows; Biogene Gueter in der Schweiz: Massen- und Energiefluesse

Energy Technology Data Exchange (ETDEWEB)

Scheurer, K; Baier, U

2001-07-01

This study supplements a series of studies carried out under the 'Energy 2000' programme and its follow-up 'SwissEnergy' on the energy potential of biomass in Switzerland. This study compiles data from existing studies and statistics and presents them as detailed mass and energy flow diagrams. The findings of the study confirm that the most important biomass fluxes are generated by animal feed stuffs and manure and that these represent an important potential for use as a source of energy. The authors state that in the foodstuffs and wood/paper industries a high level of sustainability in resource usage has been attained and that the largest losses in mass and energy flows can be found in livestock breeding and human biomass consumption.

Parameters, which effect the mass flow in the PRHRS under a natural convection condition

International Nuclear Information System (INIS)

Chung, Y. J.; Lee, G. H.; Kim, H. C.; Kim, K. K.; Zee, S. Q.

2004-01-01

load to analyze the thermal hydraulic characteristics is 100% of nominal power for a forced convection and 4% for a natural convection conditions. The 4% power natural convection condition is achieved through reducing the primary mass flow, closing the main feedwater and steam isolation valves, and opening the PRHRS isolation valves. Parameters are investigated to find the effect of the mass flow on the passive residual heat removal system under natural convection conditions. The stability regimes are identified by the disturbance amplitude of the transient parameter. If the disturbance amplitude is less than ±3%, the regime is a stable regime, more than ±5% it is an unstable regime, and between ±3% and ±5% it is considered to be a transition regime. The mass flow behavior in the passive residual heat removal system is divided into four types depending on the fluid state in both the heat exchanger and the emergency cooldown tank. The disturbance amplitudes of the mass flow are more stable with a decreasing of the height between the steam generator and the heat exchanger, and increasing the hydraulic resistance. And the effect of the initial pressure and N 2 fraction in the compensating tank, and the valve actuation time is small or negligible.(author)

A theoretical model for measuring mass flowrate and quality of two phase flow by the noise of throttling set

International Nuclear Information System (INIS)

Tong Yunxian; Wang Wenran

1992-03-01

The mass flowrate and steam quality measuring of two phase flowrate is an essential issue in the tests of loss-of-coolant accident (LOCA). The spatial stochastic distribution of phase concentration would cause a differential pressure noise when two phase flow is crossing a throttling set. Under the assumption of that the variance of disperse phase concentration is proportional to its mean phase concentration and by using the separated flow model of two phase flow, it has demonstrated that the variance of noise of differential pressure square root is approximately proportional to the flowrate of disperse phase. Thus, a theoretical model for measuring mass flowrate and quality of two phase flow by noise measurement is developed. It indicates that there is a possibility to measure two phase flowrate and steam quality by using the simple theoretical model and a single throttling set

12 CFR 225.82 - How does a bank holding company elect to become a financial holding company?

Science.gov (United States)

2010-01-01

... holding company to become a financial holding company shall not be effective if, during the period...) Effective date of election—(1) In general. An election filed by a bank holding company under paragraph (a... financial holding company is effective prior to the 31st day after the date that a complete declaration was...

Flow characteristics of a pilot-scale high temperature, short time pasteurizer.

Science.gov (United States)

Tomasula, P M; Kozempel, M F

2004-09-01

In this study, we present a method for determining the fastest moving particle (FMP) and residence time distribution (RTD) in a pilot-scale high temperature, short time (HTST) pasteurizer to ensure that laboratory or pilot-scale HTST apparatus meets the Pasteurized Milk Ordinance standards for pasteurization of milk and can be used for obtaining thermal inactivation data. The overall dimensions of the plate in the pasteurizer were 75 x 115 mm, with a thickness of 0.5 mm and effective diameter of 3.0 mm. The pasteurizer was equipped with nominal 21.5- and 52.2-s hold tubes, and flow capacity was variable from 0 to 20 L/h. Tracer studies were used to determine FMP times and RTD data to establish flow characteristics. Using brine milk as tracer, the FMP time for the short holding section was 18.6 s and for the long holding section was 36 s at 72 degrees C, compared with the nominal times of 21.5 and 52.2 s, respectively. The RTD study indicates that the short hold section was 45% back mixed and 55% plug flow for whole milk at 72 degrees C. The long hold section was 91% plug and 9% back mixed for whole milk at 72 degrees C. This study demonstrates that continuous laboratory and pilot-scale pasteurizers may be used to study inactivation of microorganisms only if the flow conditions in the holding tube are established for comparison with commercial HTST systems.

Ion Mass Determination

DEFF Research Database (Denmark)

2010-01-01

An apparatus (100) is described for determining the mass of ions, the apparatus configured to hold a plasma (101 ) having a plasma potential. The apparatus (100) comprises an electrode (102) having a surface extending in a surface plane and an insulator (104) interfacing with the electrode (102......, and a processing unit (108) configured to interpret the detected impact locations in terms of the mass of the impacting ions....

SPECIALIZATION AND SUSTAINABLE DEVELOPMENT OF AGRICULTURAL HOLDINGS

Directory of Open Access Journals (Sweden)

Zofia Kołoszko-Chomentowska

2016-03-01

Full Text Available In the present article, an attempt was made to assess the sustainability of agricultural holdings with diff erent directions of production. Agricultural holdings in the Podlaskie voivodeship registered in the FADN system in 2011–2012 were investigated. Assessment accounted for agroecological indicators (share of permanent grasslands, share of cereals in crops, soil coverage with vegetation, stock density and economic indicators (profi tableness of land and labor. Analysis was conducted according to a classifi cation into agricultural holding types: fi eldcrops, dairy cattle, and granivores. Fieldcrop and granivore holdings achieved more favourable environmental sustainability indicators. Holdings specializing in dairy cattle breeding posed a threat to the natural environment, mainly due to their excessive stock density. Economic sustainability assessment showed that granivore holdings were assessed most favorably. In these holdings, holding income per full-time worker was 37% greater than in fi eldcrop holdings and 57% greater than in dairy cattle holdings.

Modelling of the processes of heat and mass transfer in adiabatic steam and drop flows

International Nuclear Information System (INIS)

Andrizhievskij, A.A.; Mikhalevich, A.A.; Nesterenko, V.B.; Trifonov, A.G.

1983-01-01

The mathematical models for investigating the local and integral characteristics of heat and mass transfer processes during simultaneous motion of adiabatic steam and drop flow and a flux of impurity particles are given. The mathematical model is constrUcted on the basis of one-dimensional stationary eqUations of conservation of mass, thermal energy and momentum of liquid and vapor phases. Dispersion composition of condensed moisture is described by the Nukiyama-Tanasava distribution function formed taking into account the Veber number critical value. Equations of motion and mass balance conservation for impurity particles are included into the mathematical model. These equations are considered as additional inactive phase

Heat or mass transfer at low Péclet number for Brinkman and Darcy flow round a sphere

KAUST Repository

Bell, Christopher G.

2014-01-01

Prior research into the effect of convection on steady-state mass transfer from a spherical particle embedded in a porous medium has used the Darcy model to describe the flow. However, a limitation of the Darcy model is that it does not account for viscous effects near boundaries. Brinkman modified the Darcy model to include these effects by introducing an extra viscous term. Here we investigate the impact of this extra viscous term on the steady-state mass transfer from a sphere at low Péclet number, Pe 1. We use singular perturbation techniques to find the approximate asymptotic solution for the concentration profile. Mass-release from the surface of the sphere is described by a Robin boundary condition, which represents a first-order chemical reaction. We find that a larger Brinkman viscous boundary layer renders mass transport by convection less effective, and reduces the asymmetry in the peri-sphere concentration profiles. We provide simple analytical expressions that can be used to calculate the concentration profiles, as well as the local and average Sherwood numbers; and comparison to numerical simulations verifies the order of magnitude of the error in the asymptotic expansions. In the appropriate limits, the asymptotic results agree with solutions previously obtained for Stokes and Darcy flow. The solution for Darcy flow with a Robin boundary condition has not been considered previously in the literature and is a new result. Whilst the article has been formulated in terms of mass transfer, the analysis is also applicable to heat transfer, with concentration replaced by temperature and the Sherwood number by the Nusselt number. © 2013 Elsevier Ltd. All rights reserved.

Introduction to numerical modeling of thermohydrologic flow in fractured rock masses

International Nuclear Information System (INIS)

Wang, J.S.Y.

1980-01-01

More attention is being given to the possibility of nuclear waste isolation in hard rock formations. The waste will generate heat which raises the temperature of the surrounding fractured rock masses and induces buoyancy flow and pressure change in the fluid. These effects introduce the potential hazard of radionuclides being carried to the biosphere, and affect the structure of a repository by stress changes in the rock formation. The thermohydrological and thermomechanical responses are determined by the fractures as well as the intact rock blocks. The capability of modeling fractured rock masses is essential to site characterization and repository evaluation. The fractures can be modeled either as a discrete system, taking into account the detailed fracture distributions, or as a continuum representing the spatial average of the fractures. A numerical model is characterized by the governing equations, the numerical methods, the computer codes, the validations, and the applications. These elements of the thermohydrological models are discussed. Along with the general review, some of the considerations in modeling fractures are also discussed. Some remarks on the research needs in modeling fractured rock mass conclude the paper

Solid-Gas Coupling Model for Coal-Rock Mass Deformation and Pressure Relief Gas Flow in Protection Layer Mining

OpenAIRE

Zhu, Zhuohui; Feng, Tao; Yuan, Zhigang; Xie, Donghai; Chen, Wei

2018-01-01

The solid-gas coupling model for mining coal-rock mass deformation and pressure relief gas flow in protection layer mining is the key to determine deformation of coal-rock mass and migration law of pressure relief gas of protection layer mining in outburst coal seams. Based on the physical coupling process between coal-rock mass deformation and pressure-relief gas migration, the coupling variable of mining coal-rock mass, a part of governing equations of gas seepage field and deformation fiel...

Newtonian heating effect on unsteady hydromagnetic Casson fluid flow past a flat plate with heat and mass transfer

Directory of Open Access Journals (Sweden)

M. Das

2015-12-01

Full Text Available The influence of Newtonian heating on heat and mass transfer in unsteady hydromagnetic flow of a Casson fluid past a vertical plate in the presence of thermal radiation and chemical reaction is studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behavior. The fluid flow is induced due to periodic oscillations of the plate along its length and a uniform transverse magnetic field is applied in a direction which is normal to the direction of fluid flow. The partial differential equations governing the flow, heat, and mass transfer are transformed to non-dimensional form using suitable non-dimensional variables which are then solved analytically by using Laplace transform technique. The numerical values of the fluid velocity, fluid temperature, and species concentration are depicted graphically whereas the values of skin-friction, Nusselt number, and Sherwood number are presented in tabular form. It is noticed that the fluid velocity and temperature decrease with increasing values of Casson parameter while concentration decreases with increasing values of chemical reaction parameter and Schmidt number. Such a fluid flow model has several industrial and medical applications such as in glass manufacturing, paper production, purification of crude oil and study of blood flow in the cardiovascular system.

Mass spectrometric confirmation criterion for product-ion spectra generated in flow-injection analysis. Environmental application

NARCIS (Netherlands)

Geerdink, R.B.; Niessen, W.M.A.; Brinkman, U.A.T.

2001-01-01

The suitability of a confirmation criterion recently recommended in the Netherlands for gas chromatography with mass spectrometric detection (GC-MS), was evaluated for flow-injection analysis (FIA) with atmospheric pressure chemical ionisation MS-MS detection. The main feature of the criterion is

Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

Energy Technology Data Exchange (ETDEWEB)

Kramer, D.

2007-03-15

This well-illustrated, comprehensive dissertation by Dr. Ing. Denis Kramer takes an in-depth look at polymer electrolyte fuel cells (PEFC) and the possibilities for their application. First of all, the operating principles of polymer electrolyte fuel cells are described and discussed, whereby thermodynamics aspects and loss mechanisms are examined. The mass transport diagnostics made with respect to the function of the cells are discussed. Field flow geometry, gas diffusion layers and, amongst other things, liquid distribution, the influence of flow direction and the low-frequency behaviour of air-fed PEFCs are discussed. Direct methanol fuel cells are examined, as are the materials chosen. The documentation includes comprehensive mathematical and graphical representations of the mechanisms involved.

Effects of mass transfer on MHD flow of casson fluid with chemical reaction and suction

Directory of Open Access Journals (Sweden)

S. A. Shehzad

2013-03-01

Full Text Available Effect of mass transfer in the magnetohydrodynamic flow of a Casson fluid over a porous stretching sheet is addressed in the presence of a chemical reaction. A series solution for the resulting nonlinear flow is computed. The skin friction coefficient and local Sherwood number are analyzed through numerical values for various parameters of interest. The velocity and concentration fields are illustrated for several pertinent flow parameters. We observed that the Casson parameter and Hartman number have similar effects on the velocity in a qualitative sense. We further analyzed that the concentration profile decreases rapidly in comparison to the fluid velocity when we increased the values of the suction parameter.

Experimental investigation of the enthalpy and mass flow distribution between subchannels in a BWR cluster geometry (PELCO-S)

International Nuclear Information System (INIS)

Herkenrath, H.; Hufschmidt, W.

1979-01-01

Experiments based on the subchannel isokinetic technique have been carried out at the JRC of the European Community at Ispra, using a purposely designed 16-rod test section, simulating in a rather accurate way a typical BWR geometry. The adopted system allows the simultaneous determination of mass flow and enthalpy, at the end of the bundle active length, in four characteristic subchannels of the 16-rod lattice. The results show some pronounced flow and enthalpy variations within the bundle, not accurately taken into account by current subchannel codes, such as COBRA-3C. In particular low values both in mass flow and enthalpy have been found in corner subchannel, in disagreement with code predictions, but confirming previous General Electric experiments carried out in a 9-rod test section. This report deals only with the experimental procedure and the results

Improving mating performance of mass-reared sterile Mediterranean fruit flies (Diptera: Tephritidae) through changes in adult holding conditions: demography and mating competitiveness

International Nuclear Information System (INIS)

Liedo, P.; Salgado, S.; Oropeza, A.; Toledo, J.

2007-01-01

Mass rearing conditions affect the mating behavior of Mediterranean fruit flies (medflies) Ceratitis capitata (Wiedemann). We evaluated the effect of slight changes in the adult holding conditions of adult flies maintained for egg production on their mating performance. Colonization was initiated from wild flies collected as larvae from infested coffee berries (Coffea arabica L.). When pupae were close to adult emergence, they were randomly divided into 3 groups and the emerging adults were reared under the following conditions: (1) Metapa System (MS, control), consisting of 70 x 45 x 15 cm aluminum frame, mesh covered cages, with a density of 2,200 flies per cage and a 1:1 initial sex ratio; (2) Insert System (IS), with the same type of cage, and the same fly density and sex ratio as in the MS treatment, but containing twelve Plexiglas pieces (23 x 8.5 cm) to provide additional horizontal surface areas inside the cage; and (3) Sex-ratio System (SS), same as IS, but in this case the initial male: female ratio was 4:1. Three d later, newly emerged females were introduced, so the ratio became 3:1 and on the 6th d another group of newly emerged females was added to provide a 2:1 final sex ratio, at which the final density reached 1,675 flies per cage. The eggs collected from each of the 3 treatments were reared independently following standard procedures and the adults were held under the same experimental conditions. This process was repeated for over 10 to 13 generations (1 year). The experiment was repeated 3 times in 3 consecutive years, starting each replicate with a new collection of wild flies. Life tables were constructed for each treatment at the parental, 3rd, 6th, and 9th generations. Standard quality control parameters (pupation at 24 h, pupal weight, adult emergence, and flight ability), were estimated for each treatment every third generation in the third year. For the last generation each year, mating competitiveness was evaluated in field cage tests

Ultrasonic methods for locating hold-up

International Nuclear Information System (INIS)

Sinha, D.N.; Olinger, C.T.

1995-01-01

Hold-up remains one of the major contributing factors to unaccounted for materials and can be a costly problem in decontamination and decommissioning activities. Ultrasonic techniques are being developed to noninvasively monitor hold-up in process equipment where the inner surface of such equipment may be in contact with the hold-up material. These techniques may be useful in improving hold-up measurements as well as optimizing decontamination techniques

Spent Nuclear Fuel (SNF) Project Multi Canister Overpack (MCO) Process Flow Diagram Mass Balance Calculations

International Nuclear Information System (INIS)

KLEM, M.J.

2000-01-01

The purpose of this calculation document is to develop the bases for the material balances of the Multi-Canister Overpack (MCO) Level 1 Process Flow Diagram (PFD). The attached mass balances support revision two of the PFD for the MCO and provide future reference

Electrochemical mass-flow control of hydrogen using a fullerene-based proton conductor

International Nuclear Information System (INIS)

Maruyama, Ryuichiro

2002-01-01

A membrane electrode assembly (MEA) was fabricated using proton conductive hydrogensulfated fullerenol (C 60 (OSO 3 H) n (OH) n ). Rate-controlled mass flow of hydrogen was performed by applying voltage to both electrodes of the MEA without humidification. The amount of the electrochemically transported hydrogen through the MEA increased as the applied current increased, obeying Faraday's law. Residual gas analysis of the transported hydrogen showed that the transported hydrogen contains trace amounts of water less than 1%

Computation of fluid flow in distending tunnels with mass, momentum and energy exchange with the walls

Energy Technology Data Exchange (ETDEWEB)

Maw, J R [AWRE, Aldermaston (United Kingdom)

1970-05-01

When calculating the effects of an underground explosion it may be useful to be able to calculate the flow of the very hot gaseous products along pipes or tunnels. For example it might be possible to treat a fault in the surrounding rock as an idealised pipe forced open by the high pressure generated by the explosion. Another possibility might be the use of a specially constructed tunnel to channel the energy released in some preferred direction. In such cases the gas flow is complicated by several phenomena. The cross section of the pipe may vary with axial distance and also distend with time. Heat will be lost to the walls of the pipe which may be ablated leading to entrainment of wall material into the gas flow. In addition wall friction will tend to retard the flow. This paper describes a simple computer program, HAT, which was written to calculate such flows. The flow is assumed to be quasi-one-dimensional in that flow quantities such as pressure density and axial velocity do not vary across the pipe. However the radius of the pipe may vary both with axial distance and with time. Sources, or sinks of mass, momentum and energy are included in the governing equations which allow simulation of the phenomena described above. The governing equations are derived in Eulerian form and approximated using an extension of the finite difference scheme of Lax. A brief outline of the computational procedure is given. To demonstrate the capabilities and assess the accuracy of the program two simple problems are calculated using HAT (i) The motion of a shock along a converging pipe. (ii) The effect of mass addition through the walls on the motion of a shock along a uniform pipe. In both cases results obtained using HAT are compared with theoretical analyses of the motion.

A mass-conserving lattice Boltzmann method with dynamic grid refinement for immiscible two-phase flows

Energy Technology Data Exchange (ETDEWEB)

Fakhari, Abbas, E-mail: afakhari@nd.edu [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Geier, Martin [TU Braunschweig, Institute for Computational Modeling in Civil Engineering (iRMB), TU-Braunschweig, Pockelsstr. 3, 38106 Braunschweig (Germany); Lee, Taehun [Department of Mechanical Engineering, The City College of the City University of New York, New York, NY 10031 (United States)

2016-06-15

A mass-conserving lattice Boltzmann method (LBM) for multiphase flows is presented in this paper. The proposed LBM improves a previous model (Lee and Liu, 2010 [21]) in terms of mass conservation, speed-up, and efficiency, and also extends its capabilities for implementation on non-uniform grids. The presented model consists of a phase-field lattice Boltzmann equation (LBE) for tracking the interface between different fluids and a pressure-evolution LBM for recovering the hydrodynamic properties. In addition to the mass conservation property and the simplicity of the algorithm, the advantages of the current phase-field LBE are that it is an order of magnitude faster than the previous interface tracking LBE proposed by Lee and Liu (2010) [21] and it requires less memory resources for data storage. Meanwhile, the pressure-evolution LBM is equipped with a multi-relaxation-time (MRT) collision operator to facilitate attainability of small relaxation rates thereby allowing simulation of multiphase flows at higher Reynolds numbers. Additionally, we reformulate the presented MRT-LBM on nonuniform grids within an adaptive mesh refinement (AMR) framework. Various benchmark studies such as a rising bubble and a falling drop under buoyancy, droplet splashing on a wet surface, and droplet coalescence onto a fluid interface are conducted to examine the accuracy and versatility of the proposed AMR-LBM. The proposed model is further validated by comparing the results with other LB models on uniform grids. A factor of about 20 in savings of computational resources is achieved by using the proposed AMR-LBM. As a more demanding application, the Kelvin–Helmholtz instability (KHI) of a shear-layer flow is investigated for both density-matched and density-stratified binary fluids. The KHI results of the density-matched fluids are shown to be in good agreement with the benchmark AMR results based on the sharp-interface approach. When a density contrast between the two fluids exists, a

A mass-conserving lattice Boltzmann method with dynamic grid refinement for immiscible two-phase flows

International Nuclear Information System (INIS)

Fakhari, Abbas; Geier, Martin; Lee, Taehun

2016-01-01

A mass-conserving lattice Boltzmann method (LBM) for multiphase flows is presented in this paper. The proposed LBM improves a previous model (Lee and Liu, 2010 [21]) in terms of mass conservation, speed-up, and efficiency, and also extends its capabilities for implementation on non-uniform grids. The presented model consists of a phase-field lattice Boltzmann equation (LBE) for tracking the interface between different fluids and a pressure-evolution LBM for recovering the hydrodynamic properties. In addition to the mass conservation property and the simplicity of the algorithm, the advantages of the current phase-field LBE are that it is an order of magnitude faster than the previous interface tracking LBE proposed by Lee and Liu (2010) [21] and it requires less memory resources for data storage. Meanwhile, the pressure-evolution LBM is equipped with a multi-relaxation-time (MRT) collision operator to facilitate attainability of small relaxation rates thereby allowing simulation of multiphase flows at higher Reynolds numbers. Additionally, we reformulate the presented MRT-LBM on nonuniform grids within an adaptive mesh refinement (AMR) framework. Various benchmark studies such as a rising bubble and a falling drop under buoyancy, droplet splashing on a wet surface, and droplet coalescence onto a fluid interface are conducted to examine the accuracy and versatility of the proposed AMR-LBM. The proposed model is further validated by comparing the results with other LB models on uniform grids. A factor of about 20 in savings of computational resources is achieved by using the proposed AMR-LBM. As a more demanding application, the Kelvin–Helmholtz instability (KHI) of a shear-layer flow is investigated for both density-matched and density-stratified binary fluids. The KHI results of the density-matched fluids are shown to be in good agreement with the benchmark AMR results based on the sharp-interface approach. When a density contrast between the two fluids exists, a

Quantitative assessment of irradiated lung volume and lung mass in breast cancer patients treated with tangential fields in combination with deep inspiration breath hold (DIBH)

International Nuclear Information System (INIS)

Kapp, Karin Sigrid; Zurl, Brigitte; Stranzl, Heidi; Winkler, Peter

2010-01-01

Purpose: Comparison of the amount of irradiated lung tissue volume and mass in patients with breast cancer treated with an optimized tangential-field technique with and without a deep inspiration breath-hold (DIBH) technique and its impact on the normal-tissue complication probability (NTCP). Material and Methods: Computed tomography datasets of 60 patients in normal breathing (NB) and subsequently in DIBH were compared. With a Real-Time Position Management Respiratory Gating System (RPM), anteroposterior movement of the chest wall was monitored and a lower and upper threshold were defined. Ipsilateral lung and a restricted tangential region of the lung were delineated and the mean and maximum doses calculated. Irradiated lung tissue mass was computed based on density values. NTCP for lung was calculated using a modified Lyman-Kutcher-Burman (LKB) model. Results: Mean dose to the ipsilateral lung in DIBH versus NB was significantly reduced by 15%. Mean lung mass calculation in the restricted area receiving ≤ 20 Gy (M 20 ) was reduced by 17% in DIBH but associated with an increase in volume. NTCP showed an improvement in DIBH of 20%. The correlation of individual breathing amplitude with NTCP proved to be independent. Conclusion: The delineation of a restricted area provides the lung mass calculation in patients treated with tangential fields. DIBH reduces ipsilateral lung dose by inflation so that less tissue remains in the irradiated region and its efficiency is supported by a decrease of NTCP. (orig.)

Vibration Isolation by an Actively Compliantly Mounted Sensor Applied to a Coriolis Mass-Flow Meter

NARCIS (Netherlands)

van de Ridder, Bert; Hakvoort, Wouter; van Dijk, Johannes; Lötters, Joost Conrad; de Boer, Andries

2016-01-01

In this paper, a vibration isolated design of a Coriolis mass-flow meter (CMFM) is proposed by introducing a compliant connection between the casing and the tube displacement sensors, with the objective to obtain a relative displacement measurement of the fluid conveying tube, dependent on the tube

Tube holding system

International Nuclear Information System (INIS)

Cunningham, R.C.

1978-01-01

A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

Optimization of mass of plastic scintillator film for flow-cell based tritium monitoring: a Monte Carlo study

International Nuclear Information System (INIS)

Roy, Arup Singha; Palani Selvam, T.; Raman, Anand; Raja, V.; Chaudhury, Probal

2014-01-01

Over the years, various types of tritium-in-air monitors have been designed and developed based on different principles. Ionization chamber, proportional counter and scintillation detector systems are few among them. A plastic scintillator based, flow-cell type online tritium-in-air monitoring system was developed for online monitoring of tritium in air. The value of the scintillator mass inside the cell-volume, which maximizes the response of the detector system, should be obtained to get maximum efficiency. The present study is aimed to optimize the amount of mass of the plastic scintillator film for the flow-cell based tritium monitoring instrument so that maximum efficiency is achieved. The Monte Carlo based EGSnrc code system has been used for this purpose

The effects of breath-holding on pulmonary regurgitation measured by cardiovascular magnetic resonance velocity mapping

Directory of Open Access Journals (Sweden)

Babu-Narayan Sonya V

2009-01-01

Full Text Available Abstract Background Pulmonary regurgitation is a common and clinically important residual lesion after repair of tetralogy of Fallot. Cardiovascular magnetic resonance (CMR phase contrast velocity mapping is widely used for measurement of pulmonary regurgitant fraction. Breath-hold acquisitions, usually acquired during held expiration, are more convenient than the non-breath-hold approach, but we hypothesized that breath-holding might affect the amount of pulmonary regurgitation. Methods Forty-three adult patients with a previous repair of tetralogy of Fallot and residual pulmonary regurgitation were investigated with CMR. In each, pulmonary regurgitant fraction was measured from velocity maps transecting the pulmonary trunk, acquired during held expiration, held inspiration, by non-breath-hold acquisition, and also from the difference of right and left ventricular stroke volume measurements. Results Pulmonary regurgitant fraction was lower when measured by velocity mapping in held expiration compared with held inspiration, non-breath-hold or stroke volume difference (30.8 vs. 37.0, 35.6, 35.4%, p = 0.00017, 0.0035, 0.026. The regurgitant volume was lower in held expiration than in held inspiration (41.9 vs. 48.3, p = 0.0018. Pulmonary forward flow volume was larger during held expiration than during non-breath-hold (132 vs. 124 ml, p = 0.0024. Conclusion Pulmonary regurgitant fraction was significantly lower in held expiration compared with held inspiration, free breathing and stroke volume difference. Altered airway pressure could be a contributory factor. This information is relevant if breath-hold acquisition is to be substituted for non-breath-hold in the investigation of patients with a view to re-intervention.

Heat-and-mass transfer during a laminar dissociating gas flow in eccentric annular channels

International Nuclear Information System (INIS)

Besedina, T.V.; Udot, A.V.; Yakushev, A.P.

1987-01-01

An algorithm to calculate heat-and-mass transfer processes during dissociating gas laminar flow in an eccentric annular channels is considered. Analytical solutions of the heat transfer equations for a rod clodding and gap with boundary conditions of conjugation of temperatures and heat fluxes have been used to determine temperature field. This has made it possible to proceed from slution of the conjugate problem to solution of the equation of energy only for the coolant. The results of calculation of temperature distribution along the cladding for different values of its eccentricity and thermal conductivity coefficient both for the case of frozen flow and in the presence of chemical reactions in the flow are given. When calculating temperatures with conjugation boundary conditions temperature gradients in azimuthal direction are far less and heat transfer in concentration diffusion is carried out mainly in radial direction

The Practical Application of Aqueous Geochemistry in Mapping Groundwater Flow Systems in Fractured Rock Masses

Science.gov (United States)

Bursey, G.; Seok, E.; Gale, J. E.

2017-12-01

Flow to underground mines and open pits takes place through an interconnected network of regular joints/fractures and intermediate to large scale structural features such as faults and fracture zones. Large scale features can serve either as high permeability pathways or as barriers to flow, depending on the internal characteristics of the structure. Predicting long term water quality in barrier-well systems and long-term mine water inflows over a mine life, as a mine expands, requires the use of a 3D numerical flow and transport code. The code is used to integrate the physical geometry of the fractured-rock mass with porosity, permeability, hydraulic heads, storativity and recharge data and construct a model of the flow system. Once that model has been calibrated using hydraulic head and permeability/inflow data, aqueous geochemical and isotopic data provide useful tools for validating flow-system properties, when one is able to recognize and account for the non-ideal or imperfect aspects of the sampling methods used in different mining environments. If groundwater samples are collected from discrete depths within open boreholes, water in those boreholes have the opportunity to move up or down in response to the forces that drive groundwater flow, whether they be hydraulic gradients, gas pressures, or density differences associated with variations in salinity. The use of Br/Cl ratios, for example, can be used to determine if there is active flow into, or out of, the boreholes through open discontinuities in the rock mass (i.e., short-circuiting). Natural groundwater quality can also be affected to varying degrees by mixing with drilling fluids. The combined use of inorganic chemistry and stable isotopes can be used effectively to identify dilution signals and map the dilution patterns through a range of fresh, brackish and saline water types. The stable isotopes of oxygen and hydrogen are nearly ideal natural tracers of water, but situations occur when deep

Modeling hazardous mass flows Geoflows09: Mathematical and computational aspects of modeling hazardous geophysical mass flows; Seattle, Washington, 9–11 March 2009

Science.gov (United States)

Iverson, Richard M.; LeVeque, Randall J.

2009-01-01

A recent workshop at the University of Washington focused on mathematical and computational aspects of modeling the dynamics of dense, gravity-driven mass movements such as rock avalanches and debris flows. About 30 participants came from seven countries and brought diverse backgrounds in geophysics; geology; physics; applied and computational mathematics; and civil, mechanical, and geotechnical engineering. The workshop was cosponsored by the U.S. Geological Survey Volcano Hazards Program, by the U.S. National Science Foundation through a Vertical Integration of Research and Education (VIGRE) in the Mathematical Sciences grant to the University of Washington, and by the Pacific Institute for the Mathematical Sciences. It began with a day of lectures open to the academic community at large and concluded with 2 days of focused discussions and collaborative work among the participants.

Static study of traditional and ring networks and the use of mass flow control in district heating applications

International Nuclear Information System (INIS)

Kuosa, Maunu; Kontu, Kaisa; Mäkilä, Tapio; Lampinen, Markku; Lahdelma, Risto

2013-01-01

District heating (DH) systems are an inseparable part of the infrastructure in many countries. Today more attention is being paid to energy savings, efficiency improvements, and the replacement of fossil fuels by renewable energy. Research in the field of DH is focused on the supply of areas with low heat demand and low-energy buildings and on an increased share of heat being produced from renewable energy sources. New DH systems are expected to remain competitive in the future. In this study a new DH concept is proposed which is based on mass flow control. The DH system using mass flow control is meant for the concept of a ring network technology where mass flow rates in consumer substations are controlled by pumps with inverters to improve heat transfer. It will replace the traditional DH network and control in which water flow is throttled by control valves. The new control system will enable new temperature curves to be adopted for supply and return temperatures and more significant temperature cooling. First, a new topology and control method is presented. This ring network and the method used to control the flow rate of the primary supply water and its temperature are compared with the traditional technology. This method clearly shows the benefits of the DH applications under consideration. Second, these benefits are demonstrated by mathematical modelling. A simulation model is developed to study the area heating of six single-family houses and two apartment buildings. The static operation on the primary side of the networks is investigated for the most common outdoor temperatures. The numerical results are compared to those achieved with the traditional technology. The new flow rate is 46%, the pressure loss 25%, and the pumping power 12% of their former values in the pipes. The heat losses increase slightly with higher outdoor temperatures. The return temperature is lowest with the new technology. In the future the equipment that consumers will have will be

Experience gained in the process of the variable mass heat flow control implemented in the district heat supply system of the city of Gyor

Energy Technology Data Exchange (ETDEWEB)

Nagy, F.; Milanovich, L.; Lelek, J.; Kekk, I. [District Heating LTD. of Gyor (Hungary)

1996-11-01

The district heating system of the city of Gyor is fed from a hot water boiler plant. The total heat demand for 23,000 residential homes and several public facilities is 260 MW. The variable mass flow control was implemented in 1991 through 1992. Design, preparatory job and the majority of implementation was carried out without external involvement. The paper presents historical background and brief project presentation which is followed by comparative presentation of the variable mass flow control and constant mass flow control. This comparative survey has been conducted on the basis of operating data for 1993 and those for 1988. In the conclusion the gained experience is summarized.

Near-Horizontal, Two-Phase Flow Patterns of Nitrogen and Hydrogen at Low Mass Heat and Flux (on CD-ROM)

Science.gov (United States)

VanDresar, N. T.; Siegwarth, J. D.

2001-01-01

One reason for NASA's interest in cryogenic two-phase flow with low mass and heat flux is the need to design spacecraft heat exchangers used for vaporizing cryogenic propellants. The CD-ROM provides digitized movies of particular flow patterns observed in experimental work. The movies have been provided in (QuickTime9Trademark) format, encoded at 320w x 240h pixels, 15 fps, using the Sorenson(Trademark) Video Codec for compression. Experiments were conducted to obtain data on the two-phase (liquid and vapor) flow behavior of cryogenic nitrogen and hydrogen under low mass and heat flux conditions. Tests were performed in normal gravity with a 1.5 degree up flow configuration. View ports in the apparatus permitted visual observation of the two-phase flow patterns. Computer codes to predict flow patterns were developed from theoretical/empirical models reported in the literature. Predictions from the computer codes were compared with experimental flow pattern observations. Results are presented employing the traditional two-dimensional flow pattern map format using the liquid and gas superficial velocities as coordinates. In general, the agreement between the experimental results and the analytical predictive methods is reasonably good. Small regions of the flow pattern maps are identified where the models are deficient as a result of neglecting phase change phenomena. Certain regions of the maps were beyond the range of the experiments and could not be completely validated. Areas that could benefit from further work include modeling of the transition from separated flow, collection of additional data in the bubble and annular flow regimes, and collection of experimental data at other inclination angles, tube diameters and high heat flux.

Simulation of incompressible flows with heat and mass transfer using parallel finite element method

Directory of Open Access Journals (Sweden)

Jalal Abedi

2003-02-01

Full Text Available The stabilized finite element formulations based on the SUPG (Stream-line-Upwind/Petrov-Galerkin and PSPG (Pressure-Stabilization/Petrov-Galerkin methods are developed and applied to solve buoyancy-driven incompressible flows with heat and mass transfer. The SUPG stabilization term allows us to solve flow problems at high speeds (advection dominant flows and the PSPG term eliminates instabilities associated with the use of equal order interpolation functions for both pressure and velocity. The finite element formulations are implemented in parallel using MPI. In parallel computations, the finite element mesh is partitioned into contiguous subdomains using METIS, which are then assigned to individual processors. To ensure a balanced load, the number of elements assigned to each processor is approximately equal. To solve nonlinear systems in large-scale applications, we developed a matrix-free GMRES iterative solver. Here we totally eliminate a need to form any matrices, even at the element levels. To measure the accuracy of the method, we solve 2D and 3D example of natural convection flows at moderate to high Rayleigh numbers.

Spent Nuclear Fuel (SNF) Project Canister Storage Building (CSB) Process Flow Diagram Mass Balance Calculations

International Nuclear Information System (INIS)

KLEM, M.J.

2000-01-01

The purpose of these calculations is to develop the material balances for documentation of the Canister Storage Building (CSB) Process Flow Diagram (PFD) and future reference. The attached mass balances were prepared to support revision two of the PFD for the CSB. The calculations refer to diagram H-2-825869

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

Study on heat and mass transfer characteristics of humid air-flow in a fin bundle

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Hwi [Air-Conditioner Research Laboratory, LG Electronics, Seoul 153-082 (Korea); Koyama, Shigeru; Kuwahara, Ken [Department of Energy and Environmental Engineering, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Kwon, Jeong-Tae [Department of Mechanical Engineering, Hoseo University, Asan, Chungnam 336-795 (Korea); Park, Byung-Duck [School of Mechanical and Automotive Engineering, Kyungpook National University, Sangju, Gyeongbuk 742-711 (Korea)

2010-11-15

This paper deals with the heat and mass transfer characteristics of humid air-flow under frosting conditions. A slit fin bundle was used for the simulation of fins of a heat exchanger. The effects of the cooling block temperature, air humidity and air velocity on the frosting characteristics were experimentally investigated. The frosted mass was affected considerably by the cooling block temperature and air humidity. However, the effect of air velocity on it was not so large. The pressure drop was affected remarkably by all experimental parameters in this study. Local heat flux distribution and frost thickness distribution on each fin were predicted from the measured fin temperatures and the mass and energy conservation equations on the frost surface and inside the frost layer. (author)

Flow reversal in combined laminar mixed convection heat and mass transfer with phase change in a vertical channel

International Nuclear Information System (INIS)

Oulaid, Othmane; Benhamou, Brahim; Galanis, Nicolas

2010-01-01

This paper, deals with a numerical study of the effects of buoyancy forces on an upward, steady state, laminar flow of humid air in a vertical parallel-plate channel. The plates are wetted by a thin liquid water film and maintained at a constant temperature which is lower than that of the air entering the channel. A 2D fully elliptical model, associated with the Boussinesq assumption, is used to take into account axial diffusion. The solution of this mathematical model is based on the finite volume method and the velocity-pressure coupling is handled by the SIMPLER algorithm. Numerical results show that buoyancy forces have a significant effect on the hydrodynamic, thermal and mass fraction fields. Additionally, these forces induce flow reversal for high air temperatures and mass fractions at the channel entrance. It is established that heat transfer associated with phase change is, sometimes, more significant than sensible heat transfer. Furthermore, this importance depends on the mass fraction gradient. The conditions for the existence of flow reversal are presented in charts and analytical expressions specifying the critical thermal Grashof number as a function of the Reynolds number for different values of the solutal Grashof number and different aspect ratios of the channel.

Mass flows and removal of antibiotics in two municipal wastewater treatment plants.

Science.gov (United States)

Li, Bing; Zhang, Tong

2011-05-01

The mass flows and removal of 20 antibiotics of seven classes in two wastewater treatment plants (WWTPs) of Hong Kong were investigated in different seasons of a whole year, using bihourly 24h flow proportional composite samples. Antibiotics were detected at concentrations of 3.2-1718, 1.3-1176 and 1.1-233ngL(-1) in influents, secondary and disinfection effluents. Total daily discharges of all the detected antibiotics from effluents of Shatin and Stanley WWTPs were 470-710 and 3.0-5.2gd(-1), respectively. Ampicillin, cefalexin, sulfamethoxazole, sulfadiazine, sulfamethazine, chlortetracycline and vancomycin were effectively (52-100%) eliminated by activated sludge process while ampicillin and cefalexin were effectively (91-99%) eliminated by disinfection. Bihourly variation analysis showed that concentrations of the major antibiotics in influents varied more significantly in Stanley WWTP which served small communities. Copyright © 2011 Elsevier Ltd. All rights reserved.

Steady-state flow in a rock mass intersected by permeable fracture zones

International Nuclear Information System (INIS)

Lindbom, B.

1986-12-01

Level 1 of HYDROCOIN consists of seven well-defined test problems. This paper is concerned with Case 2, which is formulated as a generic groundwater flow situation often found in crystalline rock with highly permeable fracture zones in a less permeable rock mass. The case is two-dimensional and modelled with 8-noded, isoparametric, rectangular elements. According to the case definition, calculations of hydraulic head and particle tracking are performed. The computations are carried out with varying degree of discretisation in order to analyse possible impact on the result with respect to nodal density. Further calculations have been performed mainly devoted to mass balance deviations and how these are affected by permeability contrasts, varying degree of spatial discretisation and distortion of finite elements. The distribution of hydraulic head in the domain is less sensitive to differences in nodal density than the trajectories. The hydraulic heads show similar behaviour for three meshes with varying degrees of discretisation. The particle tracking seems to be more sensitive to the level of discretisation. The results obtained with a coarse and medium mesh indicate completely different solutions for one of the pathlines. The coarse mesh is too sparsely discretised for the specified problem. The local mass balance is evaluated for seven runs. The mass balance deviation seems to be considerably more sensitive to the level of discretisation than to both permeability contrasts and deformation of elements. The permeability contrasts between the rock mass and fracture zones vary from a factor of 1000 to 1 (homogeneous properties) with increments of a factor of 10. These calculations in fact give better mass balance with increasing permeability contrasts, contrary to what could be expected. (orig./HP)

Heat and mass transfer for turbulent flow of chemically reacting gas in eccentric annular channels

International Nuclear Information System (INIS)

Besedina, T.V.; Tverkovkin, B.E.; Udot, A.V.; Yakushev, A.P.

1988-01-01

Because of the possibility of using dissociating gases as coolants and working bodies of nuclear power plants, it is necessary to develop computational algorithms for calculating heat and mass transfer processes under conditions of nonequilibrium flow of chemically reacting gases not only in axisymmetric channels, but also in channels with a complex transverse cross section (including also in eccentric annular channels). An algorithm is proposed for calculating the velocity, temperature, and concentration fields under conditions of cooling of a cylindrical heat-releasing rod, placed off-center in a circular casing pipe, by a longitudinal flow of chemically reacting gas [N 2 O 4

Enhanced stability of steep channel beds to mass failure and debris flow initiation

Science.gov (United States)

Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

2015-12-01

Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

Regulation of Cross-holdings between European Companies

DEFF Research Database (Denmark)

Sørensen, Karsten Engsig

2003-01-01

Cross-holdings can be a barrier to takeovers, and they may have other disadvantages. This article analyses how cross-holdings may be regulated to avoid these negative effects.......Cross-holdings can be a barrier to takeovers, and they may have other disadvantages. This article analyses how cross-holdings may be regulated to avoid these negative effects....

Investigation of Dual-Vortical-Flow Hybrid Rocket Engine without Flame Holding Mechanism

Directory of Open Access Journals (Sweden)

A. Lai

2018-01-01

Full Text Available A 250 kgf thrust hybrid rocket engine was designed, tested, and verified in this work. Due to the injection and flow pattern of this engine, this engine was named dual-vortical-flow engine. This propulsion system uses N2O as oxidizer and HDPE as fuel. This engine was numerically investigated using a CFD tool that can handle reacting flow with finite-rate chemistry and coupled with the real-fluid model. The engine was further verified via a hot-fire test for 12 s. The ground Isp of the engine was 232 s and 221 s for numerical and hot-fire tests, respectively. An oscillation frequency with an order of 100 Hz was observed in both numerical and hot-fire tests with less than 5% of pressure oscillation. Swirling pattern on the fuel surface was also observed in both numerical and hot-fire test, which proves that this swirling dual-vortical-flow engine works exactly as designed. The averaged regression rate of the fuel surface was found to be 0.6~0.8 mm/s at the surface of disk walls and 1.5~1.7 mm/s at the surface of central core of the fuel grain.

Mass balances and energy flows, reference concept. (Spent Fuel - Copper-Iron - Bentonite - Granite)

International Nuclear Information System (INIS)

Nordman, H.; Lehikoinen, J.

2008-12-01

In this work, a semi-quantitative analysis of mass and energy flows and balances in a deep repository of the KBS-3V type subject to a glacial cycle has been carried out. The energy flows and temperatures show the maximum temperature at the canister surface not to exceed the design temperature of 100 deg C. If the measures taken to limit the water flow into the underground facilities are appropriate, the lifetime of the calcite buffer in the hydraulically conductive fracture zones was calculated to extend well beyond the operational phase of the repository. The results from hydrogeochemical model calculations in the backfill imply a long-term exchange of sodium for calcium in the clay component, if MX-80 bentonite is used. As this constitutes a potential threat to the swelling pressure of backfill in saline water environments, the physicochemical properties of a backfill should be carefully adjusted to meet its preplanned function. Despite short-lived episodes of oxygen-rich glacial water intrusion, the corrosion of the copper canister will likely be minor in the long term. (orig.)

Ring waves as a mass transport mechanism in air-driven core-annular flows.

Science.gov (United States)

Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

2012-12-01

Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

Joint test rig for testing and calibrating of different methods of two-phase mass flow measurement

International Nuclear Information System (INIS)

Reimann, J.; Arnold, G.; Chung, M.; Hahn, H.; John, H.; Mueller, S.; Wanner, E.

1977-01-01

The start-up of the steady-state steam-water loop has been finished. The planned maximal values of the mass flow rate as function of quality and pressure are reached. The components for the steady-state air-water loop have been ordered, the loop has been built up, first function tests have been carried out. Because of the additional work of the extension for air-water flows, the blowdown test rig was delayed. Calculations for the security of the pressure vessel have begun. During the experiments the knowledge of the flow regime and the apparent density is essential. To detect flow regime, impedance probes were developed and have been tested in steam-water flows at pressures up to 150 at. The probe signals can be adjointed to flow patterns even in those cases when high speed movies could not be interpreted definitely. To measure the apparent density a multiple γ-beam densitometer is developed. The collimator block and the mounting support for the γ-source were manufactured, the shielding and cooling of the scintillator has begun. (orig./RW) [de

Collective behaviors of book holding durations

Science.gov (United States)

Li, Ren-De; Guo, Qiang; Han, Jing-Ti; Liu, Jian-Guo

2016-10-01

Duration can directly reflect the collective reading behaviors of library user book holding. In this paper, by introducing the burstiness and memory coefficients, we empirically investigate the collective book holding behavior of three university libraries. The statistical results show that there are similar properties among the students with different backgrounds, presenting the burstiness = - 0.2 and memory = 0.5 for three datasets, which indicates that memory and random effects coexist in student book holding durations. In addition, we analyze the behavior patterns without duplicate durations by merging a series of books borrowed and returned at the same time. The results show the average burstiness B increases to -0.16 and memory M drops to 0.16 for three datasets, which indicates that both duplicate behavior and student's preference affect the memory effect. Furthermore, we present a model which assumes student's next book holding duration follows the previous one with probability p, and with probability 1 - p, the student would hold the book independently. The experimental results show that the presented model can reproduce the burstiness and memory effect of student book holding durations when p = 0.5 for empirical datasets and p = 0.2 for de-duplicate datasets, which indicate that the student's preferential holding behavior occurs with the probability p. This work helps in deeply understanding the regularity of duration-based human behaviors.

Ambient infrared laser ablation mass spectrometry (AIRLAB-MS) with plume capture by continuous flow solvent probe

Science.gov (United States)

O'Brien, Jeremy T.; Williams, Evan R.; Holman, Hoi-Ying N.

2017-10-31

A new experimental setup for spatially resolved ambient infrared laser ablation mass spectrometry (AIRLAB-MS) that uses an infrared microscope with an infinity-corrected reflective objective and a continuous flow solvent probe coupled to a Fourier transform ion cyclotron resonance mass spectrometer is described. The efficiency of material transfer from the sample to the electrospray ionization emitter was determined using glycerol/methanol droplets containing 1 mM nicotine and is .about.50%. This transfer efficiency is significantly higher than values reported for similar techniques.

Modelling of fluid flow through short tube orifices under metastable conditions: A new numerical validation approach for evaluating the mass flow rate with refrigerant mixtures (HFC-407C and HFC-410A)

International Nuclear Information System (INIS)

García-Valladares, O.; Santoyo, E.

2014-01-01

In a previous work, one-dimensional numerical modelling of fluid-flow inside short tube orifices was performed, and successfully validated against a wide range of mass flow rate measurements reported for the refrigerant HFC-134a. Governing equations of continuity, momentum, energy and entropy were solved for describing the fluid flow under a wide variety of thermodynamic transitions (e.g., subcooled liquid region, metastable liquid region, metastable two-phase region and equilibrium two-phase region), including sudden contraction and enlargement. In this new study, a comprehensive comparison analysis between numerical simulation data and experimental measurements obtained for HFC-407C and HFC-410A refrigerants (N o  = 241) to extend the applicability of the same mathematical model was carried out. Using a widespread statistical analysis, based on weighted linear regressions with an outlier detection/rejection module at 95% of confidence level, the prediction performance of the mathematical model was again assessed. Linear regressions between predicted mass flow rate data and experimental measurements were computed, and used them as a statistical comparison criterion. A statistical comparison between predicted simulation results and mass flow rate experimental data are reported. Average deviation errors of ±11.1% (for the refrigerant HFC-407C) and ±7.3% (for refrigerant HFC-410A) were found between numerical model and experimental data. These results demonstrate a new and robust application of the model to predict reliably the mass flow rate through short tube orifices under metastable conditions, which enable this tool to be reliably used for the design of short tube orifices. - Highlights: •A modelling for evaluating short tube orifice was developed for refrigerant mixtures. •The numerical model applied considered metastable regions and choke flow. •The model was validated against experimental data for HFC-407C and HFC-410A. •Statistical analysis based

Device for determining element contents of lignite mass flows by activation analysis

International Nuclear Information System (INIS)

Goeldner, R.; Maul, E.; Rose, W.; Wagner, D.

1987-01-01

A simple device is presented, apt for continuous operation, to determine the element contents of bulk goods of flowable materials with a suitable granularity, in particular of lignite mass flows to assess the coal quality. Several kilograms of samples can be reproducibly dosed and homogeneously activated by a device consisting of a shielding container with activation chamber and radiation source, a measuring unit with detectors, and a source container, and characterized by a blade wheel in the activation chamber which causes the dosing and homogeneous activation of the sample

Gaseous slip flow analysis of a micromachined flow sensor for ultra small flow applications

Science.gov (United States)

Jang, Jaesung; Wereley, Steven T.

2007-02-01

The velocity slip of a fluid at a wall is one of the most typical phenomena in microscale gas flows. This paper presents a flow analysis considering the velocity slip in a capacitive micro gas flow sensor based on pressure difference measurements along a microchannel. The tangential momentum accommodation coefficient (TMAC) measurements of a particular channel wall in planar microchannels will be presented while the previous micro gas flow studies have been based on the same TMACs on both walls. The sensors consist of a pair of capacitive pressure sensors, inlet/outlet and a microchannel. The main microchannel is 128.0 µm wide, 4.64 µm deep and 5680 µm long, and operated under nearly atmospheric conditions where the outlet Knudsen number is 0.0137. The sensor was fabricated using silicon wet etching, ultrasonic drilling, deep reactive ion etching (DRIE) and anodic bonding. The capacitance change of the sensor and the mass flow rate of nitrogen were measured as the inlet-to-outlet pressure ratio was varied from 1.00 to 1.24. The measured maximum mass flow rate was 3.86 × 10-10 kg s-1 (0.019 sccm) at the highest pressure ratio tested. As the pressure difference increased, both the capacitance of the differential pressure sensor and the flow rate through the main microchannel increased. The laminar friction constant f sdot Re, an important consideration in sensor design, varied from the incompressible no-slip case and the mass sensitivity and resolution of this sensor were discussed. Using the current slip flow formulae, a microchannel with much smaller mass flow rates can be designed at the same pressure ratios.

Dark chocolate reduces endothelial dysfunction after successive breath-hold dives in cool water.

Science.gov (United States)

Theunissen, Sigrid; Schumacker, Julie; Guerrero, François; Tillmans, Frauke; Boutros, Antoine; Lambrechts, Kate; Mazur, Aleksandra; Pieri, Massimo; Germonpré, Peter; Balestra, Costantino

2013-12-01

The aim of this study is to observe the effects of dark chocolate on endothelial function after a series of successive apnea dives in non-thermoneutral water. Twenty breath-hold divers were divided into two groups: a control group (8 males and 2 females) and a chocolate group (9 males and 1 female). The control group was asked to perform a series of dives to 20 m adding up to 20 min in the quiet diving pool of Conflans-Ste-Honorine (Paris, France), water temperature was 27 °C. The chocolate group performed the dives 1 h after ingestion of 30 g of dark chocolate. Flow-mediated dilatation (FMD), digital photoplethysmography, nitric oxide (NO), and peroxynitrite ONOO−) levels were measured before and after each series of breath-hold dives. A significant decrease in FMD was observed in the control group after the dives (95.28 ± 2.9 % of pre-dive values, p chocolate group (104.1 ± 2.9 % of pre-dive values, p chocolate group (98.44 ± 31.86 %, p > 0.05). No differences in digital photoplethysmography and peroxynitrites were observed between before and after the dives. Antioxidants contained in dark chocolate scavenge free radicals produced during breath-hold diving. Ingestion of 30 g of dark chocolate 1 h before the dive can thus prevent endothelial dysfunction which can be observed after a series of breath-hold dives.

Assessing the degree of plug flow in oxidation flow reactors (OFRs: a study on a potential aerosol mass (PAM reactor

Directory of Open Access Journals (Sweden)

D. Mitroo

2018-03-01

Full Text Available Oxidation flow reactors (OFRs have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flow rate. While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs inside the Washington University Potential Aerosol Mass (WU-PAM reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS model, a one-parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flow rate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F curve to that of a computational fluid dynamics (CFD simulation. The F curves, which represent the cumulative time spent in the reactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions; however sudden apertures introduce disturbances in the flow, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs to observe the effect of modified inlets, outlets and use of internals prior to application (e.g., field deployment vs. laboratory study.

Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a potential aerosol mass (PAM) reactor

Science.gov (United States)

Mitroo, Dhruv; Sun, Yujian; Combest, Daniel P.; Kumar, Purushottam; Williams, Brent J.

2018-03-01

Oxidation flow reactors (OFRs) have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flow rate). While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs) inside the Washington University Potential Aerosol Mass (WU-PAM) reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS) model, a one-parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flow rate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F curve to that of a computational fluid dynamics (CFD) simulation. The F curves, which represent the cumulative time spent in the reactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions; however sudden apertures introduce disturbances in the flow, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs to observe the effect of modified inlets, outlets and use of internals prior to application (e.g., field deployment vs. laboratory study).

Improvement of a Pneumatic Control Valve with Self-Holding Function

Science.gov (United States)

Dohta, Shujiro; Akagi, Tetsuya; Kobayashi, Wataru; Shimooka, So; Masago, Yusuke

2017-10-01

The purpose of this study is to develop a small-sized, lightweight and low-cost control valve with low energy consumption and to apply it to the assistive system. We have developed some control valves; a tiny on/off valve using a vibration motor, and an on/off valve with self-holding function. We have also proposed and tested the digital servo valve with self-holding function using permanent magnets and a small-sized servo motor. In this paper, in order to improve the valve, an analytical model of the digital servo valve is proposed. And the simulated results by using the analytical model and identified parameters were compared with the experimental results. Then, the improved digital servo valve was designed based on the calculated results and tested. As a result, we realized the digital servo valve that can control the flow rate more precisely while maintaining its volume and weight compared with the previous valve. As an application of the improved valve, a position control system of rubber artificial muscle was built and the position control was performed successfully.

Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans.

Science.gov (United States)

Kjeld, Thomas; Pott, Frank C; Secher, Niels H

2009-04-01

The diving response is initiated by apnea and facial immersion in cold water and includes, besides bradycardia, peripheral vasoconstriction, while cerebral perfusion may be enhanced. This study evaluated whether facial immersion in 10 degrees C water has an independent influence on cerebral perfusion evaluated as the middle cerebral artery mean flow velocity (MCA V(mean)) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (Pa(CO(2))) from 4.2 to 6.7 kPa and MCA V(mean) from 37 to 103 cm/s (mean; approximately 178%; P breath hold increased Pa(CO(2)) from 5.9 to 8.2 kPa (P breath hold diverts blood toward the brain with a >100% increase in MCA V(mean), largely because Pa(CO(2)) increases, but the increase in MCA V(mean) becomes larger when combined with facial immersion in cold water independent of Pa(CO(2)).

Breath-Hold Diving.

Science.gov (United States)

Fitz-Clarke, John R

2018-03-25

Breath-hold diving is practiced by recreational divers, seafood divers, military divers, and competitive athletes. It involves highly integrated physiology and extreme responses. This article reviews human breath-hold diving physiology beginning with an historical overview followed by a summary of foundational research and a survey of some contemporary issues. Immersion and cardiovascular adjustments promote a blood shift into the heart and chest vasculature. Autonomic responses include diving bradycardia, peripheral vasoconstriction, and splenic contraction, which help conserve oxygen. Competitive divers use a technique of lung hyperinflation that raises initial volume and airway pressure to facilitate longer apnea times and greater depths. Gas compression at depth leads to sequential alveolar collapse. Airway pressure decreases with depth and becomes negative relative to ambient due to limited chest compliance at low lung volumes, raising the risk of pulmonary injury called "squeeze," characterized by postdive coughing, wheezing, and hemoptysis. Hypoxia and hypercapnia influence the terminal breakpoint beyond which voluntary apnea cannot be sustained. Ascent blackout due to hypoxia is a danger during long breath-holds, and has become common amongst high-level competitors who can suppress their urge to breathe. Decompression sickness due to nitrogen accumulation causing bubble formation can occur after multiple repetitive dives, or after single deep dives during depth record attempts. Humans experience responses similar to those seen in diving mammals, but to a lesser degree. The deepest sled-assisted breath-hold dive was to 214 m. Factors that might determine ultimate human depth capabilities are discussed. © 2018 American Physiological Society. Compr Physiol 8:585-630, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

Effect of free swirl flow on the rate of mass and heat transfer at the bottom of a vertical cylindrical container and possible applications

International Nuclear Information System (INIS)

Konsowa, A.H.; Abdel-Aziz, M.H.; Abdo, M.S.E.; Hassan, M.S.; Sedahmed, G.H.

2017-01-01

Highlights: • Mass transfer at the bottom of a cylindrical container was studied under decaying swirl flow. • Parameters studied are swirl flow velocity, diameter of the inlet nozzle and solution properties. • A dimensionless equation was obtained using the significant parameters. • The present results were compared with the results obtained using perpendicular inlet nozzle. • Relevance of study to the design of membrane processes was highlighted. - Abstract: Rates of mass transfer at the base of a vertical cylindrical container were determined under decaying swirl flow by the electrochemical technique. Variables studied were swirl flow solution velocity, diameter of the tangential inlet nozzle and physical properties of the solution. The data were correlated by a dimensionless mass transfer equation. The equation can be used to predict the rate of heat loss from the bottom of swirl flow equipment as well as the rate of diffusion controlled corrosion of the bottom. The importance of the derived equation in the design and scale up of a cylindrical batch recirculating catalytic or electrochemical reactor with a catalyst layer or electrode at the bottom and a cooling jacket around the vertical wall suitable for conducting exothermic liquid – solid diffusion controlled reactions which need rapid temperature control to avoid the loss of heat sensitive catalysts or heat sensitive products was pointed out. Comparison of the present results with the results obtained using perpendicular inlet nozzle which generates parallel flow at the bottom and axial flow along the cylindrical container revealed the fact that although swirl flow produces higher rates of heat and mass transfer at the cylindrical wall than axial flow and the reverse is true at the container base. Relevance of the present study to the design and operation of membrane processes and heat recovery from hot pools of liquid metals and low melting alloys in the production stage was highlighted.

Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow.

Science.gov (United States)

Carlos Varas, Álvaro E; Peters, E A J F; Kuipers, J A M

2017-05-17

We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas-solid contact efficiencies. Cluster gas-solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

Mure skal holde zombierne ude

DEFF Research Database (Denmark)

Stockmarr, Leila

2013-01-01

Vi bygger som besatte mure og barrierer for at holde flygtninge ude og tæmme de negative konsekvenser af den neoliberale globalisering.......Vi bygger som besatte mure og barrierer for at holde flygtninge ude og tæmme de negative konsekvenser af den neoliberale globalisering....

Mussel colonization of a high flow artificial benthic habitat: Byssogenesis holds the key.

NARCIS (Netherlands)

Rajagopal, S.; Venugopalan, V.P.; Velde, G. van der; Jenner, H.A.

2006-01-01

Water flow is an important characteristic determining the settlement and growth of macroinvertebrates in the marine environment. Intake systems of coastal power stations offer a unique opportunity to study the effect of water flow on benthic organisms under field conditions. The cooling water intake

[The role of patient flow and surge capacity for in-hospital response in mass casualty events].

Science.gov (United States)

Sefrin, Peter; Kuhnigk, Herbert

2008-03-01

Mass casualty events make demands on emergency services and disaster control. However, optimized in- hospital response defines the quality of definitive care. Therefore, German federal law governs the role of hospitals in mass casualty incidents. In hospital casualty surge is depending on resources that have to be expanded with a practicable alarm plan. Thus, in-hospital mass casualty management planning is recommended to be organized by specialized persons. To minimise inhospital patient overflow casualty surge principles have to be implemented in both, pre-hospital and in-hospital disaster planning. World soccer championship 2006 facilitated the initiation of surge and damage control principles in in-hospital disaster planning strategies for German hospitals. The presented concept of strict control of in-hospital patient flow using surge principles minimises the risk of in-hospital breakdown and increases definitive hospital treatment capacity in mass casualty incidents.

Optimization of information content in a mass spectrometry based flow-chemistry system by investigating different ionization approaches.

Science.gov (United States)

Martha, Cornelius T; Hoogendoorn, Jan-Carel; Irth, Hubertus; Niessen, Wilfried M A

2011-05-15

Current development in catalyst discovery includes combinatorial synthesis methods for the rapid generation of compound libraries combined with high-throughput performance-screening methods to determine the associated activities. Of these novel methodologies, mass spectrometry (MS) based flow chemistry methods are especially attractive due to the ability to combine sensitive detection of the formed reaction product with identification of introduced catalyst complexes. Recently, such a mass spectrometry based continuous-flow reaction detection system was utilized to screen silver-adducted ferrocenyl bidentate catalyst complexes for activity in a multicomponent synthesis of a substituted 2-imidazoline. Here, we determine the merits of different ionization approaches by studying the combination of sensitive detection of product formation in the continuous-flow system with the ability to simultaneous characterize the introduced [ferrocenyl bidentate+Ag](+) catalyst complexes. To this end, we study the ionization characteristics of electrospray ionization (ESI), atmospheric-pressure chemical ionization (APCI), no-discharge APCI, dual ESI/APCI, and dual APCI/no-discharge APCI. Finally, we investigated the application potential of the different ionization approaches by the investigation of ferrocenyl bidentate catalyst complex responses in different solvents. Copyright © 2011 Elsevier B.V. All rights reserved.

Experimental and numerical analysis of heat transfer phenomena in a sensor tube of a mass flow controller

International Nuclear Information System (INIS)

Jang, Seok Pil; Kim, Sung Jin; Choi, Do Hyung

2000-01-01

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution

Positive-column plasma studied by fast-flow glow discharge mass spectrometry: Could it be a 'Rydberg gas?'

International Nuclear Information System (INIS)

Mason, Rod S.; Miller, Pat D.; Mortimer, Ifor; Mitchell, David J.; Dash, Neil A.

2003-01-01

Ions created from the fast-flowing positive column plasma of a glow discharge were monitored using a high voltage magnetic sector mass spectrometer. Since the field gradient and sheath potentials created by the plasma inside the source opposed cation transfer, it is inferred that the ions detected were the field-ionized Rydberg species. This is supported by the mass spectral changes which occurred when a negative bias was applied to the sampling aperture and by the contrasting behavior when attached to a quadrupole analyzer. Reaction with H 2 (titrated into the flowing plasma) quenched not only the ionization of discharge gas Rydberg atoms but also the passage of electric current through the plasma, without significant changes to the field and sheath potentials. Few 'free' ions were present and the lifetimes of the Rydberg atoms detected were much longer than seen in lower pressure experiments, indicating additional stabilization in the plasma environment. The observations support the model of the flowing plasma, given previously [R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)] as mainly a neutral Rydberg atom gas, rather than a conventional ion-electron plasma

MHD heat and mass diffusion flow by natural convection past a surface embedded in a porous medium

Directory of Open Access Journals (Sweden)

Chaudhary R.C.

2009-01-01

Full Text Available This paper presents an analytical study of the transient hydromagnetic natural convection flow past a vertical plate embedded in a porous medium, taking account of the presence of mass diffusion and fluctuating temperature about time at the plate. The governing equations are solved in closed form by the Laplace-transform technique. The results are obtained for temperature, velocity, penetration distance, Nusselt number and skin-friction. The effects of various parameters are discussed on the flow variables and presented by graphs.

State of the art of numerical modeling of thermohydrologic flow in fractured rock mass

International Nuclear Information System (INIS)

Wang, J.S.Y.; Tsang, C.F.; Sterbentz, R.A.

1983-01-01

The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses is reviewed and a comparative study is made of several models which have been developed in nuclear waste isolation, geothermal energy, ground-water hydrology, petroleum engineering, and other geologic fields. The general review is followed by separate summaries of the main characteristics of the governing equations, numerical solutions, computer codes, validations, and applications for each model

Leg blood flow is impaired during small muscle mass exercise in patients with COPD

DEFF Research Database (Denmark)

Iepsen, Ulrik Winning; Munch, Gregers Druedal Wibe; Rugbjerg, Mette

2017-01-01

to both endothelium-independent (SNP) and endothelium-dependent (ACh) stimulation. The results suggests that leg muscle blood flow is impaired during small muscle mass exercise in patients with COPD possibly due to impaired formation of prostacyclin and increased levels of endothelin-1.......Skeletal muscle blood flow is regulated to match the oxygen demand and dysregulation could contribute to exercise intolerance in patients with COPD. We measured leg hemodynamics and metabolites from vasoactive compounds in muscle interstitial fluid and plasma at rest, during one-legged knee...... the formation of interstitial prostacyclin (vasodilator) was only increased in the controls. There was no difference between groups in the nitrite/nitrate levels (vasodilator) in plasma or interstitial fluid during exercise. Moreover, patients and controls showed similar vasodilatory capacity in response...

Evaluation of Flow-Injection Tandem Mass Spectrometry for Rapid and High-Throughput Quantitative Determination of B-Vitamins in Nutritional Supplements

Energy Technology Data Exchange (ETDEWEB)

Bhandari, Deepak [ORNL; Van Berkel, Gary J [ORNL

2012-01-01

The use of flow-injection electrospray ionization tandem mass spectrometry for rapid and high-throughput mass spectral analysis of selected B-vitamins, viz. B1, B2, B3, B5, and B6, in nutritional formulations was demonstrated. A simple and rapid (~5 min) in-tube sample preparation was performed by adding extraction solvent to a powdered sample aliquot followed by agitation, centrifugation, and filtration to recover an extract for analysis. Automated flow injection introduced 1 L of the extracts directly into the mass spectrometer ion source without chromatographic separation. Sample-to-sample analysis time was 60 s representing significant improvement over conventional liquid chromatography approaches which typically require 25-45 min, and often require more significant sample preparation procedures. Quantitative capabilities of the flow-injection analysis were tested using the method of standard additions and NIST standard reference material (SRM 3280) multivitamin/multielement tablets. The quantity determined for each B-vitamin in SRM 3280 was within the statistical range provided for the respective certified values. The same sample preparation and analysis approach was also applied to two different commercial vitamin supplement tablets and proved to be successful in the quantification of the selected B-vitamins as evidenced by an agreement with the labels values and the results obtained using isotope dilution liquid chromatography/mass spectrometry.

Electroplating method for producing ultralow-mass fissionable deposits

International Nuclear Information System (INIS)

Ruddy, F.H.

1989-01-01

A method for producing ultralow-mass fissionable deposits for nuclear reactor dosimetry is described, including the steps of holding a radioactive parent until the radioactive parent reaches secular equilibrium with a daughter isotope, chemically separating the daughter from the parent, electroplating the daughter on a suitable substrate, and holding the electroplated daughter until the daughter decays to the fissionable deposit

Provably Correct Control-Flow Graphs from Java Programs with Exceptions

NARCIS (Netherlands)

Amighi, A.; de Carvalho Gomes, Pedro; Huisman, Marieke

2011-01-01

We present an algorithm to extract flow graphs from Java bytecode, focusing on exceptional control flows. We prove its correctness, meaning that the behaviour of the extracted control-flow graph is an over-approximation of the behaviour of the original program. Thus any safety property that holds

In vivo proton MRS of normal pancreas metabolites during breath-holding and free-breathing

International Nuclear Information System (INIS)

Su, T.-H.; Jin, E.-H.; Shen, H.; Zhang, Y.; He, W.

2012-01-01

Aim: To characterize normal pancreas metabolites using in vivo proton magnetic resonance spectroscopy ( 1 H MRS) at 3 T under conditions of breath-holding and free-breathing. Materials and methods: The pancreases of 32 healthy volunteers were examined using 1 H MRS during breath-holding and free-breathing acquisitions in a single-voxel point-resolved selective spectroscopy sequence (PRESS) technique using a 3 T MRI system. Resonances were compared between paired spectra of the two breathing modes. Furthermore, correlations between lipid (Lip) content and age, body-mass index (BMI), as well as choline (Cho) peak visibility of the normal pancreas were analysed during breath-holding. Results: Twenty-nine pairs of spectra were successfully obtained showing three major resonances, Lip, Cho, cholesterol and the unsaturated parts of the olefinic region of fatty acids (Chol + Unsat). Breath-hold spectra were generally better, with higher signal-to-noise ratios (SNR; Z=–2.646, p = 0.008) and Cho peak visible status (Z=–2.449, p = 0.014). Correlations were significant between spectra acquired by the two breathing modes, especially for Lip height, Lip area, and the area of other peaks at 1.9–4.1 ppm. However, the Lip resonance was significantly different between the spectra of the two breathing modes (p 1 H MRS of the normal pancreas at 3 T is technically feasible and can characterize several metabolites. 1 H MRS during breath-holding acquisition is superior to that during free-breathing acquisition.

Delta Flow Modulator

NARCIS (Netherlands)

Stamhuis, Eize; Lengkeek, W

2015-01-01

A support structure (2) is installed in or near a water (50). The support structure is holding a deltalike-wing (3) under an angle of incidence relative to an incoming flow (54), caused by at least a prevailing current in the water, thus generating a vortex (77). The action of the vortex is

Heat or mass transfer at low Péclet number for Brinkman and Darcy flow round a sphere

KAUST Repository

Bell, Christopher G.; Byrne, H.M.; Whiteley, J.P.; Waters, S.L.

2014-01-01

Prior research into the effect of convection on steady-state mass transfer from a spherical particle embedded in a porous medium has used the Darcy model to describe the flow. However, a limitation of the Darcy model is that it does not account

Performance of a liquid-junction interface for capillary electrophoresis mass spectrometry using continuous-flow fast-atom bombardment

NARCIS (Netherlands)

Reinhoud, N.J.; Niessen, W.M.A.; Tjaden, U.R.; Gramberg, L.G.; Verheij, E.R.; Greef, J. van der

1989-01-01

The on-line coupling of capillary electrophoresis and mass spectrometry using a continuous-flow fast-atom bombardment system in combination with a liquid-junction interface is described. The influence of the liquid-junction coupling on the efficiency and the resolution is investigated. Qualitative

Fractionation and Characterization of High Aspect Ratio Gold Nanorods Using Asymmetric-Flow Field Flow Fractionation and Single Particle Inductively Coupled Plasma Mass Spectrometry

Directory of Open Access Journals (Sweden)

Thao M. Nguyen

2015-07-01

Full Text Available Gold nanorods (GNRs are of particular interest for biomedical applications due to their unique size-dependent longitudinal surface plasmon resonance band in the visible to near-infrared. Purified GNRs are essential for the advancement of technologies based on these materials. Used in concert, asymmetric-flow field flow fractionation (A4F and single particle inductively coupled mass spectrometry (spICP-MS provide unique advantages for fractionating and analyzing the typically complex mixtures produced by common synthetic procedures. A4F fractions collected at specific elution times were analyzed off-line by spICP-MS. The individual particle masses were obtained by conversion of the ICP-MS pulse intensity for each detected particle event, using a defined calibration procedure. Size distributions were then derived by transforming particle mass to length assuming a fixed diameter. The resulting particle lengths correlated closely with ex situ transmission electron microscopy. In contrast to our previously reported observations on the fractionation of low-aspect ratio (AR GNRs (AR < 4, under optimal A4F separation conditions the results for high-AR GNRs of fixed diameter (≈20 nm suggest normal, rather than steric, mode elution (i.e., shorter rods with lower AR generally elute first. The relatively narrow populations in late eluting fractions suggest the method can be used to collect and analyze specific length fractions; it is feasible that A4F could be appropriately modified for industrial scale purification of GNRs.

Method of mechanical holding of cantilever chip for tip-scan high-speed atomic force microscope

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Shingo [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Uchihashi, Takayuki; Ando, Toshio [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Bio-AFM Frontier Research Center, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Core Research for Evolutional Science and Technology of the Japan Science and Technology Agency, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076 (Japan)

2015-06-15

In tip-scan atomic force microscopy (AFM) that scans a cantilever chip in the three dimensions, the chip body is held on the Z-scanner with a holder. However, this holding is not easy for high-speed (HS) AFM because the holder that should have a small mass has to be able to clamp the cantilever chip firmly without deteriorating the Z-scanner’s fast performance, and because repeated exchange of cantilever chips should not damage the Z-scanner. This is one of the reasons that tip-scan HS-AFM has not been established, despite its advantages over sample stage-scan HS-AFM. Here, we present a novel method of cantilever chip holding which meets all conditions required for tip-scan HS-AFM. The superior performance of this novel chip holding mechanism is demonstrated by imaging of the α{sub 3}β{sub 3} subcomplex of F{sub 1}-ATPase in dynamic action at ∼7 frames/s.

Allowance Holdings and Transfers Data Inventory

Data.gov (United States)

U.S. Environmental Protection Agency — The Allowance Holdings and Transfers Data Inventory contains measured data on holdings and transactions of allowances under the NOx Budget Trading Program (NBP), a...

Gravity assisted recovery of liquid xenon at large mass flow rates

Science.gov (United States)

Virone, L.; Acounis, S.; Beaupère, N.; Beney, J.-L.; Bert, J.; Bouvier, S.; Briend, P.; Butterworth, J.; Carlier, T.; Chérel, M.; Crespi, P.; Cussonneau, J.-P.; Diglio, S.; Manzano, L. Gallego; Giovagnoli, D.; Gossiaux, P.-B.; Kraeber-Bodéré, F.; Ray, P. Le; Lefèvre, F.; Marty, P.; Masbou, J.; Morteau, E.; Picard, G.; Roy, D.; Staempflin, M.; Stutzmann, J.-S.; Visvikis, D.; Xing, Y.; Zhu, Y.; Thers, D.

2018-06-01

We report on a liquid xenon gravity assisted recovery method for nuclear medical imaging applications. The experimental setup consists of an elevated detector enclosed in a cryostat connected to a storage tank called ReStoX. Both elements are part of XEMIS2 (XEnon Medical Imaging System): an innovative medical imaging facility for pre-clinical research that uses pure liquid xenon as detection medium. Tests based on liquid xenon transfer from the detector to ReStoX have been successfully performed showing that an unprecedented mass flow rate close to 1 ton per hour can be reached. This promising achievement as well as future areas of improvement will be discussed in this paper.

12 CFR 1252.1 - Enterprise portfolio holding criteria.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Enterprise portfolio holding criteria. 1252.1 Section 1252.1 Banks and Banking FEDERAL HOUSING FINANCE AGENCY ENTERPRISES PORTFOLIO HOLDINGS § 1252.1 Enterprise portfolio holding criteria. The Enterprises are required to comply with the portfolio holdings...

12 CFR 225.124 - Foreign bank holding companies.

Science.gov (United States)

2010-01-01

... SYSTEM BANK HOLDING COMPANIES AND CHANGE IN BANK CONTROL (REGULATION Y) Regulations Financial Holding Companies Interpretations § 225.124 Foreign bank holding companies. (a) Effective December 1, 1971, the... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Foreign bank holding companies. 225.124 Section...

Excess cash holdings and shareholder value

OpenAIRE

Lee, Edward; Powell, Ronan

2011-01-01

We examine the determinants of corporate cash holdings in Australia and the impact on shareholder wealth of holding excess cash. Our results show that a trade-off model best explains the level of a firm’s cash holdings in Australia. We find that 'transitory' excess cash firms earn significantly higher risk-adjusted returns compared to 'persistent' excess cash firms, suggesting that the market penalises firms that hoard cash. The marginal value of cash also declines with larger cash balances, ...

Effects of heat and mass transfer on peristaltic flow of a Bingham fluid in the presence of inclined magnetic field and channel with different wave forms

International Nuclear Information System (INIS)

Akram, Safia; Nadeem, S.; Hussain, Anwar

2014-01-01

In the present analysis we discussed the influence of heat and mass transfer on the peristaltic flow of a Bingham in an inclined magnetic field and channel with different wave forms. The governing two dimensional equations of momentum, heat and mass transfer are simplified under the assumptions of long wavelength and low Reynolds number approximation. The exact solutions of momentum, heat and mass transfer are calculated. Finally, graphical behaviors of various physical parameters are also discussed through the graphical behavior of pressure rise, pressure gradient, temperature concentration and stream functions. - Highlights: • Combine effects of heat and mass transfer on peristaltic flow problem is discussed. • Effects of inclined magnetic field and channel on new fluid model are discussed. • Effects of different wave forms are also discussed in the present flow problem

12 CFR 575.14 - Subsidiary holding companies.

Science.gov (United States)

2010-01-01

... follows: Federal MHC Subsidiary Holding Company Charter Section 1. Corporate title. The full corporate... subsidiary holding company available for distribution, in cash or in kind. Each share of common stock shall... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Subsidiary holding companies. 575.14 Section...

On the dynamics of non-stationary binary stellar system with non-isotropic mass flow

International Nuclear Information System (INIS)

Bekov, A.A.; Bejsekov, A.N.; Aldibaeva, L.T.

2006-01-01

The motion of test body in the external gravitational field of the binary stellar systems with slowly variable some physical parameters of radiating components is considered on the base of restricted nonstationary photo-gravitational three and two bodies problem with non-isotropic mass flow. The family of polar and coplanar solutions are obtained. The solutions give the possibility of the dynamical and structure interpretation of binary young evolving stars and galaxies. (author)

Transition from annular flow to plug/slug flow in condensation of steam in microchannels

Energy Technology Data Exchange (ETDEWEB)

Quan, Xiaojun; Cheng, Ping; Wu, Huiying [School of Mechanical and Power Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Shanghai 200240 (China)

2008-02-15

A visualization study has been conducted to investigate the transition from annular flow to plug/slug flow in the condensation of steam in two different sets of parallel microchannels, having hydraulic diameters of 90 {mu}m and 136 {mu}m, respectively. The steam in the parallel microchannels was cooled on the bottom by forced convection of water and by natural convection of air from the top. It is found that the location, where the transition from annular flow to plug/slug flow takes place, depends on mass flux and cooling rate of steam. The effects of mass flux and cooling rate on the occurrence frequency of the injection flow in a single microchannel, having a hydraulic diameter of 120 {mu}m and 128 {mu}m, respectively, are investigated. It is found that two different shapes of injection flow occur in the smooth annular flow in microchannels: injection flow with unsteady vapor ligament occurring at low mass flux (or high cooling rate) and injection flow with steady vapor ligament occurring at high mass flux (or low cooling rate). It is also found that increase of steam mass flux, decrease of cooling rate, or decrease of the microchannel diameter tends to enhance instability of the condensate film on the wall, resulting in occurrence of the injection flow further toward the outlet with an increase in occurrence frequency. (author)

Influence of blood flow occlusion on the development of peripheral and central fatigue during small muscle mass handgrip exercise.

Science.gov (United States)

Broxterman, R M; Craig, J C; Smith, J R; Wilcox, S L; Jia, C; Warren, S; Barstow, T J

2015-09-01

Critical power represents an important threshold for neuromuscular fatigue development and may, therefore, dictate intensities for which exercise tolerance is determined by the magnitude of fatigue accrued. Peripheral fatigue appears to be constant across O2 delivery conditions for large muscle mass exercise, but this consistency is equivocal for smaller muscle mass exercise. We sought to determine the influence of blood flow occlusion during handgrip exercise on neuromuscular fatigue development and to examine the relationship between neuromuscular fatigue development and W '. Blood flow occlusion influenced the development of both peripheral and central fatigue, thus providing further evidence that the magnitude of peripheral fatigue is not constant across O2 delivery conditions for small muscle mass exercise. W ' appears to be related to the magnitude of fatigue accrued during exercise, which may explain the reported consistency of intramuscular metabolic perturbations and work performed for severe-intensity exercise. The influence of the muscle metabolic milieu on peripheral and central fatigue is currently unclear. Moreover, the relationships between peripheral and central fatigue and the curvature constant (W ') have not been investigated. Six men (age: 25 ± 4 years, body mass: 82 ± 10 kg, height: 179 ± 4 cm) completed four constant power handgrip tests to exhaustion under conditions of control exercise (Con), blood flow occlusion exercise (Occ), Con with 5 min post-exercise blood flow occlusion (Con + Occ), and Occ with 5 min post-exercise blood flow occlusion (Occ + Occ). Neuromuscular fatigue measurements and W ' were obtained for each subject. Each trial resulted in significant peripheral and central fatigue. Significantly greater peripheral (79.7 ± 5.1% vs. 22.7 ± 6.0%) and central (42.6 ± 3.9% vs. 4.9 ± 2.0%) fatigue occurred for Occ than for Con. In addition, significantly greater peripheral (83.0 ± 4.2% vs. 69.0 ± 6.2%) and central

Concept on groundwater flow and mass transport through heterogeneous porous media and application to in-situ test analysis

International Nuclear Information System (INIS)

Hatanaka, Koichiro; Umeki, Hiroyuki.

1995-01-01

Generally, geological media is modelled as porous or fractured media depending on their characteristics. Since the channels of groundwater flow and the transport paths are determined by the heterogeneity of the geological media, quantitative understanding of the heterogeneity is an important issue for modelling flow and transport processes through them. Therefore, it becomes popular way to develop statistical identification approaches of the heterogeneous field by using data from in-situ test and conduct validation studies of flow and transport models through the field by comparing with observed data. In this report, the theories of the identification approach and the concept on groundwater flow and mass transport are explained briefly and the application to tracer tests conducted at Grimsel test site, Switzerland, are described. (author)

Analysis of two-phase flow inter-subchannel mass and momentum exchanges by the two-fluid model approach

Energy Technology Data Exchange (ETDEWEB)

Ninokata, H. [Tokyo Institute of Technology (Japan); Deguchi, A. [ENO Mathematical Analysis, Tokyo (Japan); Kawahara, A. [Kumamoto Univ., Kumamoto (Japan)

1995-09-01

A new void drift model for the subchannel analysis method is presented for the thermohydraulics calculation of two-phase flows in rod bundles where the flow model uses a two-fluid formulation for the conservation of mass, momentum and energy. A void drift model is constructed based on the experimental data obtained in a geometrically simple inter-connected two circular channel test sections using air-water as working fluids. The void drift force is assumed to be an origin of void drift velocity components of the two-phase cross-flow in a gap area between two adjacent rods and to overcome the momentum exchanges at the phase interface and wall-fluid interface. This void drift force is implemented in the cross flow momentum equations. Computational results have been successfully compared to experimental data available including 3x3 rod bundle data.

Investigation of technology for the monitoring of UF6 mass flow in UF6 streams diluted with H2

International Nuclear Information System (INIS)

Baker, O.J.; Cooley, J.N.; Hewgley, W.A.; Moran, B.W.; Swindle, D.W. Jr.

1986-12-01

The applicability, availability, and effectiveness of gas flow meters are assessed as a means for verifying the mass flows of pure UF 6 streams diluted with a carrier gas. The initial survey identified the orifice, pitot tube, thermal, vortex shedding, and vortex precession (swirl) meters as promising for the intended use. Subsequent assessments of these flow meters revealed that two - the orifice meter and the pitot tube meter - are the best choices for the proposed applications: the first is recommended for low velocity gas, small diameter piping; the latter, for high velocity gas, large diameter piping. Final selection of the gas flow meters should be based on test loop evaluations in which the proposed meters are subjected to gas flows, temperatures, and pressures representative of those expected in service. Known instruments are evaluated that may be applicable to the measurement of uranium or UF 6 concentration in a UF 6 - H 2 process stream at an aerodynamic enrichment plant. Of the six procedures evaluated, four have been used for process monitoring in a UF 6 environment: gas mass spectrometry, infrared-ultraviolet-visible spectrophotometry, gas chromatography, and acoustic gas analysis. The remaining two procedures, laser fluorimetry and atomic absorption spectroscopy, would require significant development work before they could be used for process monitoring. Infrared-ultravioloet-visible spectrophotometry is judged to be the best procedure currently available to perform the required measurement

Two-phase flow through small branches in a horizontal pipe with stratified flow

International Nuclear Information System (INIS)

Smoglie, C.

1984-12-01

This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HP) [de

Pulsed flow modulation two-dimensional comprehensive gas chromatography-tandem mass spectrometry with supersonic molecular beams.

Science.gov (United States)

Poliak, Marina; Fialkov, Alexander B; Amirav, Aviv

2008-11-07

Pulsed flow modulation (PFM) two-dimensional comprehensive gas chromatography (GC x GC) was combined with quadrupole-based mass spectrometry (MS) via a supersonic molecular beam (SMB) interface using a triple-quadrupole system as the base platform, which enabled tandem mass spectrometry (MS-MS). PFM is a simple GC x GC modulator that does not consume cryogenic gases while providing tunable second GC x GC column injection time for enabling the use of quadrupole-based mass spectrometry regardless its limited scanning speed. The 20-ml/min second column flow rate involved with PFM is handled, splitless, by the SMB interface without affecting the sensitivity. The combinations of PFM GC x GC-MS with SMB and PFM GC x GC-MS-MS with SMB were explored with the analysis of diazinon and permethrin in coriander. PFM GC x GC-MS with SMB is characterized by enhanced molecular ion and tailing-free fast ion source response time. It enables universal pesticide analysis with full scan and data analysis with reconstructed single ion monitoring on the enhanced molecular ion and another prominent high mass fragment ion. The elimination of the third fragment ion used in standard three ions method results in significantly reduced matrix interference. GC x GC-MS with SMB improves the GC separation, and thereby our ability for sample identification using libraries. GC-MS-MS with SMB provides better reduction (elimination) of matrix interference than GC x GC-MS. However, it is a target method, which is not always applicable. GC x GC-MS-MS does not seem to further reduce matrix interferences over GC-MS-MS and unlike GC x GC-MS, it is incompatible with library identification, but it is beneficial to have both GC x GC and MS-MS capabilities in the same system.

Sports-related lung injury during breath-hold diving

Directory of Open Access Journals (Sweden)

Tanja Mijacika

2016-12-01

Full Text Available The number of people practising recreational breath-hold diving is constantly growing, thereby increasing the need for knowledge of the acute and chronic effects such a sport could have on the health of participants. Breath-hold diving is potentially dangerous, mainly because of associated extreme environmental factors such as increased hydrostatic pressure, hypoxia, hypercapnia, hypothermia and strenuous exercise. In this article we focus on the effects of breath-hold diving on pulmonary function. Respiratory symptoms have been reported in almost 25% of breath-hold divers after repetitive diving sessions. Acutely, repetitive breath-hold diving may result in increased transpulmonary capillary pressure, leading to noncardiogenic oedema and/or alveolar haemorrhage. Furthermore, during a breath-hold dive, the chest and lungs are compressed by the increasing pressure of water. Rapid changes in lung air volume during descent or ascent can result in a lung injury known as pulmonary barotrauma. Factors that may influence individual susceptibility to breath-hold diving-induced lung injury range from underlying pulmonary or cardiac dysfunction to genetic predisposition. According to the available data, breath-holding does not result in chronic lung injury. However, studies of large populations of breath-hold divers are necessary to firmly exclude long-term lung damage.

The effects of mass flows on the dissipation of Alfvacute en waves in the upper layers of the solar atmosphere

International Nuclear Information System (INIS)

Ryutova, M.P.; Habbal, S.R.

1995-01-01

The influence of parallel plasma flows on the propagation of shear Alfvacute en waves along magnetic structures is considered. It is shown that even in a simple case of regular mass flows directed along the magnetic field, their presence considerably modifies the dissipation of shear Alfvacute en waves, affecting both the magnitude and the height of maximum dissipation. The strongest effect occurs in the case of downflows when the flow velocity at a certain height becomes equal to the Alfvacute en velocity. Near that point, the wave comes to extinction and gives off its energy completely. The axial extent of the absorption region is evaluated. This effect can be directly associated with observed high-velocity downflows in the transition region, and, in particular, can serve as a qualitative explanation for the high variability of the emission observed near 10 5 K. In the presence of upward mass flows and moderate downflows, the dissipation of phase-mixed Alfvacute en waves is accompanied by the radial redistribution of the energy input across the magnetic structure, thus creating a mosaic pattern in the emitting regions. The flow velocities are assumed to be below the thresholds which correspond to the onset of hydrodynamic and dissipative instabilities. copyright 1995 The American Astronomical Society

49 CFR 178.338-9 - Holding time.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Holding time. 178.338-9 Section 178.338-9... Specifications for Containers for Motor Vehicle Transportation § 178.338-9 Holding time. (a) “Holding time” is the time, as determined by testing, that will elapse from loading until the pressure of the contents...

Two-phase heat and mass transfer in turbulent parallel and countercurrent flows of liquid film and gas

International Nuclear Information System (INIS)

Kholpanov, L.P.; Babak, T.B.; Babak, V.N.; Malyusov, V.A.; Zhavoronkov, N.M.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

1980-01-01

To determine the ways of intensification of heat and mass transfer processes, the direct flow and counterflow heat and mass transfer is analytically investigated during the turbulent flow of a liquid and gas film on the basis of solving the energy equation for liquid and gas film, i.e. the two-phase film heat transfer is investigated from the position of a conjugate task. The analysis of the two-phase heat transfer has shown that it is necessary to know the position of each point in a plane before using this or that formula. Depending on its position on this plane, the heat transfer process will be determined by one or two phases only. It is found, that in the case of a single-phase heat transfer the temperature on the surface remains stable over the channel length. In the case of a two-phase heat transfer it can significantly change over the channel length [ru

Proceedings of the workshop on numerical modeling of thermohydrological flow in fractured rock masses

International Nuclear Information System (INIS)

1980-09-01

Nineteen papers were presented at the workshop on modeling thermohydrologic flow in fractured masses. This workshop was a result of the interest currently being given to the isolation of nuclear wastes in geologic formations. Included in these proceedings are eighteen of the presentations, one abstract and summaries of the panel discussions. The papers are listed under the following categories: introduction; overviews; fracture modelings; repository studies; geothermal models; and recent developments. Eighteen of the papers have been abstracted and indexed

Accretion flow dynamics during 1999 outburst of XTE J1859+226—modeling of broadband spectra and constraining the source mass

Science.gov (United States)

Nandi, Anuj; Mandal, S.; Sreehari, H.; Radhika, D.; Das, Santabrata; Chattopadhyay, I.; Iyer, N.; Agrawal, V. K.; Aktar, R.

2018-05-01

We examine the dynamical behavior of accretion flow around XTE J1859+226 during the 1999 outburst by analyzing the entire outburst data (˜166 days) from RXTE Satellite. Towards this, we study the hysteresis behavior in the hardness intensity diagram (HID) based on the broadband (3-150 keV) spectral modeling, spectral signature of jet ejection and the evolution of Quasi-periodic Oscillation (QPO) frequencies using the two-component advective flow model around a black hole. We compute the flow parameters, namely Keplerian accretion rate (\\dot{m}d), sub-Keplerian accretion rate (\\dot{m}h), shock location (rs) and black hole mass (M_{bh}) from the spectral modeling and study their evolution along the q-diagram. Subsequently, the kinetic jet power is computed as L^{obs}_{jet} ˜3-6 ×10^{37} erg s^{-1} during one of the observed radio flares which indicates that jet power corresponds to 8-16% mass outflow rate from the disc. This estimate of mass outflow rate is in close agreement with the change in total accretion rate (˜14%) required for spectral modeling before and during the flare. Finally, we provide a mass estimate of the source XTE J1859+226 based on the spectral modeling that lies in the range of 5.2-7.9 M_{⊙} with 90% confidence.

Analysis of humic colloid borne trace elements by flow field-flow fractionation, gel permeation chromatography and icp-mass spectrometry

International Nuclear Information System (INIS)

Ngo, Manh Thang; Beck, H.P; Geckeis, H.; Kim, J.I.

1999-01-01

Groundwater samples containing aquatic humic substances are analyzed by flow field- flow fractionation (FFFF) and gel permeation chromatography (GPC). Natural concentrations of U, Th and rare earth elements (REE) in a size-fractionated groundwater sample are analyzed by on-line coupling of inductively coupled plasma-mass spectrometry (ICP-MS) to either FFFF or GPC. The uranium, thorium, and REE are found to be quantitatively attached to colloidal species in the investigated groundwater sample. Their distribution in different colloid size fractions, however, is quite heterogeneous. Both, FFFF and GPC reveal that Th and REE are preferentially located in the size fraction > 50 kDalton. U is also attached to low molecular weight humic acid, similar to Fe and Al. This finding could be qualitatively reproduced by sequential ultrafiltration. The results are interpreted in terms of different binding mechanisms for the individual elements in the heterogeneous humic macromolecules. The inclusion of actinides into larger aggregates of aquatic humic acid might explain the considerable kinetic hindrance of actinide-humic acid dissociation reactions described in the literature. (authors)

Rotation and Radiation Effects on MHD Flow through Porous Medium Past a Vertical Plate with Heat and Mass Transfer

Directory of Open Access Journals (Sweden)

Uday Singh Rajput

2017-11-01

Full Text Available Effects of rotation and radiation on unsteady MHD flow past a vertical plate with variable wall temperature and mass diffusion in the presence of Hall current is studied here. Earlier we studied chemical reaction effect on unsteady MHD flow past an exponentially accelerated inclined plate with variable temperature and mass diffusion in the presence of Hall current. We had obtained the results which were in agreement with the desired flow phenomenon. To study further, we are changing the model by considering radiation effect on fluid, and changing the geometry of the model. Here in this paper we are taking the plate positioned vertically upward and rotating with velocity Ω . Further, medium of the flow is taken as porous. The plate temperature and the concentration level near the plate increase linearly with time. The governing system of partial differential equations is transformed to dimensionless equations using dimensionless variables. The dimensionless equations under consideration have been solved by Laplace transform technique. The model contains equations of motion, diffusion equation and equation of energy. To analyze the solution of the model, desirable sets of the values of the parameters have been considered. The governing equations involved in the flow model are solved by the Laplace-transform technique. The results obtained have been analyzed with the help of graphs drawn for different parameters. The numerical values obtained for the drag at boundary and Nusselt number have been tabulated. We found that the values obtained for velocity, concentration and temperature are in concurrence with the actual flow of the fluid

Structural instability of atmospheric flows under perturbations of the mass balance and effect in transport calculations

International Nuclear Information System (INIS)

Núñez, M A; Mendoza, R

2015-01-01

Several methods to estimate the velocity field of atmospheric flows, have been proposed to the date for applications such as emergency response systems, transport calculations and for budget studies of all kinds. These applications require a wind field that satisfies the conservation of mass but, in general, estimated wind fields do not satisfy exactly the continuity equation. An approach to reduce the effect of using a divergent wind field as input in the transport-diffusion equations, was proposed in the literature. In this work, a linear local analysis of a wind field, is used to show analytically that the perturbation of a large-scale nondivergent flow can yield a divergent flow with a substantially different structure. The effects of these structural changes in transport calculations are illustrated by means of analytic solutions of the transport equation

FINE MAGNETIC STRUCTURE AND ORIGIN OF COUNTER-STREAMING MASS FLOWS IN A QUIESCENT SOLAR PROMINENCE

International Nuclear Information System (INIS)

Shen, Yuandeng; Liu, Yu; Xu, Zhi; Liu, Zhong; Liu, Ying D.; Chen, P. F.; Su, Jiangtao

2015-01-01

We present high-resolution observations of a quiescent solar prominence that consists of a vertical and a horizontal foot encircled by an overlying spine and has ubiquitous counter-streaming mass flows. While the horizontal foot and the spine were connected to the solar surface, the vertical foot was suspended above the solar surface and was supported by a semicircular bubble structure. The bubble first collapsed, then reformed at a similar height, and finally started to oscillate for a long time. We find that the collapse and oscillation of the bubble boundary were tightly associated with a flare-like feature located at the bottom of the bubble. Based on the observational results, we propose that the prominence should be composed of an overlying horizontal spine encircling a low-lying horizontal and vertical foot, in which the horizontal foot consists of shorter field lines running partially along the spine and has ends connected to the solar surface, while the vertical foot consists of piling-up dips due to the sagging of the spine fields and is supported by a bipolar magnetic system formed by parasitic polarities (i.e., the bubble). The upflows in the vertical foot were possibly caused by the magnetic reconnection at the separator between the bubble and the overlying dips, which intruded into the persistent downflow field and formed the picture of counter-streaming mass flows. In addition, the counter-streaming flows in the horizontal foot were possibly caused by the imbalanced pressure at the both ends

Extreme mass ratio inspiral rates: dependence on the massive black hole mass

International Nuclear Information System (INIS)

Hopman, Clovis

2009-01-01

We study the rate at which stars spiral into a massive black hole (MBH) due to the emission of gravitational waves (GWs), as a function of the mass M . of the MBH. In the context of our model, it is shown analytically that the rate approximately depends on the MBH mass as M -1/4 . . Numerical simulations confirm this result, and show that for all MBH masses, the event rate is highest for stellar black holes, followed by white dwarfs, and lowest for neutron stars. The Laser Interferometer Space Antenna (LISA) is expected to see hundreds of these extreme mass ratio inspirals per year. Since the event rate derived here formally diverges as M . → 0, the model presented here cannot hold for MBHs of masses that are too low, and we discuss what the limitations of the model are.

Heat-transfer and pressure distributions for laminar separated flows downstream of rearward-facing steps with and without mass suction

Science.gov (United States)

Brown, R. D.; Jakubowski, A. K.

1974-01-01

Heat-transfer and pressure distributions were measured for laminar separated flows downstream of rearward-facing steps with and without mass suction. The flow conditions were such that the boundary-layer thickness was comparable to or larger than the step height. For both suction and no-suction cases, an increase in the step height resulted in a sharp decrease in the initial heat-transfer rates behind the step. Downstream, however, the heat transfer gradually recovered back to less than or near attached-flow values. Mass suction from the step base area increased the local heat-transfer rates; however, this effect was relatively weak for the laminar flows considered. Even removal of the entire approaching boundary layer raised the post-step heat-transfer rates only about 10 percent above the flatplate values. Post-step pressure distributions were found to depend on the entrainment conditions at separation. In the case of the solid-faced step, a sharp pressure drop behind the step was followed by a very short plateau and relatively fast recompression. For the slotted-step connected to a large plenum but without suction, the pressure drop at the base was much smaller and the downstream recompression more gradual than that for solid-faced step.

Tribocorrosion in pressurized high temperature water: a mass flow model based on the third body approach

Energy Technology Data Exchange (ETDEWEB)

Guadalupe Maldonado, S.

2014-07-01

Pressurized water reactors (PWR) used for power generation are operated at elevated temperatures (280-300 °C) and under higher pressure (120-150 bar). In addition to these harsh environmental conditions some components of the PWR assemblies are subject to mechanical loading (sliding, vibration and impacts) leading to undesirable and hardly controllable material degradation phenomena. In such situations wear is determined by the complex interplay (tribocorrosion) between mechanical, material and physical-chemical phenomena. Tribocorrosion in PWR conditions is at present little understood and models need to be developed in order to predict component lifetime over several decades. The goal of this project, carried out in collaboration with the French company AREVA NP, is to develop a predictive model based on the mechanistic understanding of tribocorrosion of specific PWR components (stainless steel control assemblies, stellite grippers). The approach taken here is to describe degradation in terms of electro-chemical and mechanical material flows (third body concept of tribology) from the metal into the friction film (i.e. the oxidized film forming during rubbing on the metal surface) and from the friction film into the environment instead of simple mass loss considerations. The project involves the establishment of mechanistic models for describing the single flows based on ad-hoc tribocorrosion measurements operating at low temperature. The overall behaviour at high temperature and pressure in investigated using a dedicated tribometer (Aurore) including electrochemical control of the contact during rubbing. Physical laws describing the individual flows according to defined mechanisms and as a function of defined physical parameters were identified based on the obtained experimental results and from literature data. The physical laws were converted into mass flow rates and solved as differential equation system by considering the mass balance in compartments

Gas mass transfer for stratified flows

International Nuclear Information System (INIS)

Duffey, R.B.; Hughes, E.D.

1995-01-01

We analyzed gas absorption and release in water bodies using existing surface renewal theory. We show a new relation between turbulent momentum and mass transfer from gas to water, including the effects of waves and wave roughness, by evaluating the equilibrium integral turbulent dissipation due to energy transfer to the water from the wind. Using Kolmogoroff turbulence arguments the gas transfer velocity, or mass transfer coefficient, is then naturally and straightforwardly obtained as a non-linear function of the wind speed drag coefficient and the square root of the molecular diffusion coefficient. In dimensionless form, the theory predicts the turbulent Sherwood number to be Sh t = (2/√π)Sc 1/2 , where Sh t is based on an integral dissipation length scale in the air. The theory confirms the observed nonlinear variation of the mass transfer coefficient as a function of the wind speed; gives the correct transition with turbulence-centered models for smooth surfaces at low speeds; and predicts experimental data from both laboratory and environmental measurements within the data scatter. The differences between the available laboratory and field data measurements are due to the large differences in the drag coefficient between wind tunnels and oceans. The results also imply that the effect of direct aeration due to bubble entrainment at wave breaking is no more than a 20% increase in the mass transfer for the highest speeds. The theory has importance to mass transfer in both the geo-physical and chemical engineering literature

Measurement of mass flux in high temperature high pressure steam-water two-phase flow using a combination of Pitot tubes and a gamma densitometer

International Nuclear Information System (INIS)

Chan, A.M.C.; Bzovey, D.

1990-01-01

The design and calibration of a two-phase mass-flux measurement device making use of a Pitot-tube rake and a gamma densitometer are described. Five Pitot tubes and three chordal void-fraction measurements are used. Similar devices have been reported previously. The present device is designed for easy operation and simple data interpretation for both axisymmetric and non-axisymmetric flows under high pressure transient two-phase flow conditions. The device was calibrated using a vertical two-phase flow loop as well as a model-scale pump loop in horizontal orientation. Good agreement between the measured two-phase mass fluxes and the single-phase values was obtained in both cases. (orig.)

The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses

International Nuclear Information System (INIS)

Wang, J.S.Y.; Sterbentz, R.A.; Tsang, C.F.

1982-01-01

The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses is reviewed and a comparative study is made of several models which have been developed in nuclear waste isolation, geothermal energy, ground water hydrology, petroleum engineering, and other geologic fields. The general review is followed by individual summaries of each model and the main characteristics of its governing equations, numerical solutions, computer codes, validations, and applications

Regional blood flows in the established stage of reduced renal mass (RRM) hypertension in rats

International Nuclear Information System (INIS)

Smits, G.J.; Lombard, J.H.

1986-01-01

Regional blood flows were measured with 15 μm 153 Gd-labelled microspheres in 21 anesthetized (pentobarbital-50 mg/kg, i.p.) male Sprague Dawley rats 5-6 weeks after a 75% reduction in renal mass and in 6 sham operated controls (SOC). RRM rats were maintained on either a high salt (HS-RRM) diet, i.e., choice of 1% NaCl or tap water (n = 11), or on a salt-restricted (SR-RRM) diet (n = 10). Mean arterial blood pressure was significantly elevated (mean +/- SE) in the HS-RRM (168 +/- 5 mmHg) vs. either the SR-RRM (147 +/- 6 mmHg) or the SOC (138 +/- 4 mmHg). Although blood flow to the skin and femur were elevated in HS-RRM and SR-RRM relative to SOC, there were no significant differences in blood flow to skeletal muscle, spleen, liver, small intestine, stomach or testes between any of the groups. Absolute renal blood flow and renal blood flow/gm of tissue were significantly lower in HS-RRM (7.2 +/- 0.7 ml/min or 3.4 +/- 0.5 ml/min/gm) and SR-RRM (6.3 +/- 0.6 ml/min or 3.2 +/- 0.3 ml/min/gm) than in SOC (15.1 +/- 0.97 ml/min or 5.5 +/- 0.2 ml/min/gm). The present results suggest that regional blood flow is unchanged in most vascular beds during the established stage of RRM hypertension in rats

Investigations on the enrichment behaviour of toxic heavy metals in the mass flows of a coal power station

International Nuclear Information System (INIS)

Biehusen, U.

1980-01-01

In the present work solid sample material from a coal power plant has been analyzed, and by means of establishing a mass balance and calculating enrichment factors the question of how the heavy-metals having entered the power plant via the coal are distributed over the individual mass flows leaving the plant has been explained. Radioactive substances that get into the plant with the uranium and thorium contained in the coal have been considered in the same way. (orig./EF) [de

Two-phase flow through small branches in a horizontal pipe with stratified flow

International Nuclear Information System (INIS)

Smoglie, C.

1985-02-01

In the field of reactor safety the occurrence of a small break in a horizontal primary coolant pipe is of great importance. This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HS) [de

Holdings of the Federal German Government in 1988

International Nuclear Information System (INIS)

1989-01-01

The report provides an overview of the direct and more important indirect holdings of the Federal German Government and its special assets ERP, Compensation Fund, Federal Mail and Federal Railway. Part A provides a total survey of the number of government holdings. For the direct holdings of the Federal Government and its special assets the shares in nominal capital and registered foundation capital, number of employees and dividend on profits are presented. In Parts B to M, the narrative parts, the most important holdings are reported on more in detail (sphere of activities, economic development, composition of the corporate bodies). The listing order does not reflect any order of importance. The following part N contains alphabetic indexes. Indexes I and II list all the direct holdings of the Federal Government and its special assets irrespective of the nominal capital volume and share of holdings. In index III, are listed only companies with corporate activites and a nominal capital of at least 100.000 German Marks of which the Federal Government and/or its special assets hold directly or indirectly at least 25 percent. Holdings of these undertakings of which the Federal Government does not have majority ownership, and which are not dependent on it under the regulations governing shareholdings either, are not considered. (orig.) [de

Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

Science.gov (United States)

Alexandrou, Constantia; Athenodorou, Andreas; Cichy, Krzysztof; Constantinou, Martha; Horkel, Derek P.; Jansen, Karl; Koutsou, Giannis; Larkin, Conor

2018-04-01

We compare lattice QCD determinations of topological susceptibility using a gluonic definition from the gradient flow and a fermionic definition from the spectral-projector method. We use ensembles with dynamical light, strange and charm flavors of maximally twisted mass fermions. For both definitions of the susceptibility we employ ensembles at three values of the lattice spacing and several quark masses at each spacing. The data are fitted to chiral perturbation theory predictions with a discretization term to determine the continuum chiral condensate in the massless limit and estimate the overall discretization errors. We find that both approaches lead to compatible results in the continuum limit, but the gluonic ones are much more affected by cutoff effects. This finally yields a much smaller total error in the spectral-projector results. We show that there exists, in principle, a value of the spectral cutoff which would completely eliminate discretization effects in the topological susceptibility.

Study of turbulent natural-circulation flow and low-Prandtl-number forced-convection flow

International Nuclear Information System (INIS)

Chung, K.S.; Thompson, D.H.

1980-01-01

Calculational methods and results are discussed for the coupled energy and momentum equations of turbulent natural circulation flow and low Prandtl number forced convection flow. The objective of this paper is to develop a calculational method for the study of the thermal-hydraulic behavior of coolant flowing in a liquid metal fast breeder reactor channel under natural circulation conditions. The two-equation turbulence model is used to evaluate the turbulent momentum transport property. Because the analogy between momentum transfer and heat transfer does not generally hold for low Prandtl number fluid and natural circulation flow conditions, the turbulent thermal conductivity is calculated independently using equations similar to the two-equation turbulence model. The numerical technique used in the calculation is the finite element method

Breath-Holding Spells

Science.gov (United States)

... reviewed: October 2016 More on this topic for: Parents Is It Normal for Children to Hold Their Breath? Taming Tempers Disciplining Your Child Disciplining Your Toddler Temper Tantrums Separation Anxiety View more About Us Contact Us Partners ...

Assessment of Mass Transfer Coefficients in Coalescing Slug Flow in Vertical Pipes and Applications to Tubular Airlift Membrane Bioreactors

DEFF Research Database (Denmark)

Ratkovich, Nicolas Rios; Berube, P.R.; Nopens, I.

2011-01-01

by the gas flow. It was noted that coalescence of bubbles affects the MTH. Coalescence increased the “width” of the peaks (i.e. the estimate of the variability of the mass transfer coefficient) and the height of the peak (i.e. amount of time that a mass transfer coefficient of a given value is maintained......). A semi-empirical relationship based on the Lévêque relationship for the Sherwood number (mass transfer coefficient) was formulated for the laminar regime. A test case comparison between water and activated sludge was performed based on full-scale airlift MBR operational conditions. It was found...

76 FR 20459 - Savings and Loan Holding Company Application

Science.gov (United States)

2011-04-12

... DEPARTMENT OF THE TREASURY Office of Thrift Supervision Savings and Loan Holding Company... concerning the following information collection. Title of Proposal: Savings and Loan Holding Company... officer of a savings and loan holding company, or any individual who owns, controls, or holds with power...

Combined natural convection and mass transfer effects on unsteady flow past an infinite vertical porous plate embedded in a porous medium with heat source

Energy Technology Data Exchange (ETDEWEB)

Das, S.S. [Department of Physics, K B D A V College, Nirakarpur, Khurda-752 019 (Orissa) (India); Tripathy, R.K. [Department of Physics, D R Nayapalli College, Bhubaneswar-751 012 (Orissa) (India); Padhy, R.K. [Department of Physics, D A V Public School, Chandrasekharpur, Bhubaneswar-751 021 (Orissa) (India); Sahu, M. [Department of Physics, Jupiter +2 Women’s Science College, IRC Village, Bhubaneswar-751 015 (Orissa) (India)

2012-07-01

This paper theoretically investigates the combined natural convection and mass transfer effects on unsteady flow of a viscous incompressible fluid past an infinite vertical porous plate embedded in a porous medium with heat source. The governing equations of the flow field are solved analytically for velocity, temperature, concentration distribution, skin friction and the rate of heat transfer using multi parameter perturbation technique and the effects of the flow parameters such as permeability parameter Kp, Grashof number for heat and mass transfer Gr, Gc; heat source parameter S, Schmidt number Sc, Prandtl number Pr etc. on the flow field are analyzed and discussed with the help of figures and tables. The permeability parameter Kp is reported to accelerate the transient velocity of the flow field at all points for small values of Kp (£1) and for higher values the effect reverses. The effect of increasing Grashof numbers for heat and mass transfer or heat source parameter is to enhance the transient velocity of the flow field at all points while a growing Schmidt number retards its effect at all points. A growing permeability parameter or heat source parameter increases the transient temperature of the flow field at all points, while a growing Prandtl number shows reverse effect. The effect of increasing Schmidt number is to decrease the concentration boundary layer thickness of the flow field at all points. Further, a growing permeability parameter enhances the skin friction at the wall and a growing Prandtl number shows reverse effect. The effect of increasing Prandtl number or permeability parameter leads to increase the magnitude of the rate of heat transfer at the wall.

Blue breath holding is benign.

OpenAIRE

Stephenson, J B

1991-01-01

In their recent publication in this journal, Southall et al described typical cyanotic breath holding spells, both in otherwise healthy children and in those with brainstem lesions and other malformations. Their suggestions regarding possible autonomic disturbances may require further study, but they have adduced no scientific evidence to contradict the accepted view that in the intact child blue breath holding spells are benign. Those families in which an infant suffers an 'apparently life t...

A dilute-and-shoot flow-injection tandem mass spectrometry method for quantification of phenobarbital in urine.

Science.gov (United States)

Alagandula, Ravali; Zhou, Xiang; Guo, Baochuan

2017-01-15

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the gold standard of urine drug testing. However, current LC-based methods are time consuming, limiting the throughput of MS-based testing and increasing the cost. This is particularly problematic for quantification of drugs such as phenobarbital, which is often analyzed in a separate run because they must be negatively ionized. This study examined the feasibility of using a dilute-and-shoot flow-injection method without LC separation to quantify drugs with phenobarbital as a model system. Briefly, a urine sample containing phenobarbital was first diluted by 10 times, followed by flow injection of the diluted sample to mass spectrometer. Quantification and detection of phenobarbital were achieved by an electrospray negative ionization MS/MS system operated in the multiple reaction monitoring (MRM) mode with the stable-isotope-labeled drug as internal standard. The dilute-and-shoot flow-injection method developed was linear with a dynamic range of 50-2000 ng/mL of phenobarbital and correlation coefficient > 0.9996. The coefficients of variation and relative errors for intra- and inter-assays at four quality control (QC) levels (50, 125, 445 and 1600 ng/mL) were 3.0% and 5.0%, respectively. The total run time to quantify one sample was 2 min, and the sensitivity and specificity of the method did not deteriorate even after 1200 consecutive injections. Our method can accurately and robustly quantify phenobarbital in urine without LC separation. Because of its 2 min run time, the method can process 720 samples per day. This feasibility study shows that the dilute-and-shoot flow-injection method can be a general way for fast analysis of drugs in urine. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Operation characteristic of a R123-based organic Rankine cycle depending on working fluid mass flow rates and heat source temperatures

International Nuclear Information System (INIS)

Feng, Yong-Qiang; Hung, Tzu-Chen; Wu, Shang-Lun; Lin, Chih-Hung; Li, Bing-Xi; Huang, Kuo-Chen; Qin, Jiang

2017-01-01

Highlights: • The operation characteristic of an Organic Rankine Cycle using R123 and a scroll expander have been investigated. • The behaviors and detailed discussion for those four major components are examined. • The expander isentropic efficiency presents a slight decrease first and then a sharp increase with mass flow rate. • The maximum electrical power and system generation efficiency are 2.01 kW and 3.25%, respectively. - Abstract: The test and operation characteristic of an organic Rankine cycle using R123 and a scroll expander have been investigated. The steady-state operation characteristic is addressed with the varying working fluid mass flow rates ranging of 0.124–0.222 kg/s and heat source temperatures ranging of 383.15–413.15 K. The behaviors and detailed discussion for those four major components (pump, evaporator, expander and condenser) are examined. The experimental results show that the environmental temperature presents a higher influence on the pump behaviors. The range of pump power consumption, isentropic efficiency and back work ratio are 0.21–0.32 kW, 26.76–53.96%, and 14–32%, respectively. The expander isentropic efficiency presents a slight decrease first and then a sharp increase with mass flow rate, while a degree of superheating more than 3 K is necessary to avoid expander cavitation. The expander isentropic and generator efficiencies are in range of 69.10–85.17% and 60–73%, respectively, while the respective heat transfer coefficients for evaporator and condenser are ranging of 200–400 and 450–2000 W/m"2 K. The maximum expander shaft power and electrical power are 2.78 kW and 2.01 kW, respectively, while the maximum system generating efficiency is 3.25%. Moreover, the tested thermal efficiency presents a slight decrease trend with mass flow rate.

Radiated chemical reaction impacts on natural convective MHD mass transfer flow induced by a vertical cone

Science.gov (United States)

Sambath, P.; Pullepu, Bapuji; Hussain, T.; Ali Shehzad, Sabir

2018-03-01

The consequence of thermal radiation in laminar natural convective hydromagnetic flow of viscous incompressible fluid past a vertical cone with mass transfer under the influence of chemical reaction with heat source/sink is presented here. The surface of the cone is focused to a variable wall temperature (VWT) and wall concentration (VWC). The fluid considered here is a gray absorbing and emitting, but non-scattering medium. The boundary layer dimensionless equations governing the flow are solved by an implicit finite-difference scheme of Crank-Nicolson which has speedy convergence and stable. This method converts the dimensionless equations into a system of tri-diagonal equations and which are then solved by using well known Thomas algorithm. Numerical solutions are obtained for momentum, temperature, concentration, local and average shear stress, heat and mass transfer rates for various values of parameters Pr, Sc, λ, Δ, Rd are established with graphical representations. We observed that the liquid velocity decreased for higher values of Prandtl and Schmidt numbers. The temperature is boost up for decreasing values of Schimdt and Prandtl numbers. The enhancement in radiative parameter gives more heat to liquid due to which temperature is enhanced significantly.

12 CFR 583.20 - Savings and loan holding company.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Savings and loan holding company. 583.20... REGULATIONS AFFECTING SAVINGS AND LOAN HOLDING COMPANIES § 583.20 Savings and loan holding company. The term savings and loan holding company means any company that directly or indirectly controls a savings...

An initial study on modeling the global thermal and fast reactor fuel cycle mass flow using Vensim

International Nuclear Information System (INIS)

Brinton, Samuel

2008-01-01

This study concentrated on modeling the construction and decommissioning rates of five major facilities comprising the nuclear fuel cycle: (1) current LWRs with a 60-year service life, (2) new LWRs burning MOX fuel, (3) new LWRs to replace units in the current fleet, (4) new FRs to be added to the fleet, and (5) new spent fuel reprocessing facilities. This is a mass flow mode starting from uranium ore and following it to spent forms. The visual dynamic modeling program Vensim was used to create a system of equations and variables to track the mass flows from enrichment, fabrication, burn-up, and the back-end of the fuel cycle. The scenarios considered provide estimates of the uranium ore requirements, quantities of LLW and HLW production, and the number of reprocessing facilities necessary to reduce recently reported levels of spent fuel inventory. Preliminary results indicate that the entire national spent fuel inventory produced in the next 100 years can be reprocessed with a reprocessing plant built every 11 years (small capacity) or even as low as every 23 years (large capacity). (authors)

Choked flow mechanism of HFC-134a flowing through short-tube orifices

Energy Technology Data Exchange (ETDEWEB)

Nilpueng, Kitti; Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), Department of Mechanical Engineering, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok (Thailand)

2011-02-15

This paper is a continuation of the author's previous work. New experimental data on the occurrence of choked flow phenomenon and mass flow rate of HFC-134a inside short-tube orifices under choked flow condition are presented. Short-tube orifices diameters ranging from 0.406 mm to 0.686 mm with lengths ranging from 1 mm to 3 mm which can be applied to a miniature vapour-compression refrigeration system are examined. The experimental results indicated that the occurrence of choked flow phenomena inside short-tube orifices is different from that obtained from short-tube orifice diameters of greater than 1 mm, which are typically used in air-conditioner. The beginning of choked flow is dependent on the downstream pressure, degree of subcooling, and length-to-diameter ratio. Under choked flow condition, the mass flow rate is greatly varied with the short-tube orifice dimension, but it is slightly affected by the operating conditions. A correlation of mass flow rate through short-tube orifices is proposed in terms of the dimensionless parameters. The predicted results show good agreement with experimental data with a mean deviation of 4.69%. (author) transfer coefficient was also proposed. (author)

Transient radiative hydromagnetic free convection flow past an impulsively started vertical plate with uniform heat and mass flux

Directory of Open Access Journals (Sweden)

Prasad Ramachandra V.

2006-01-01

Full Text Available The interaction of free convection with thermal radiation of viscous incompressible MHD unsteady flow past an impulsively started vertical plate with uniform heat and mass flux is analyzed. This type of problem finds application in many technological and engineering fields such as rocket propulsion systems, space craft re-entry aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace engineering .The Rosseland approximation is used to describe the radiative heat transfer in the limit of the optically thin fluid. The non-linear, coupled equations are solved using an implicit finite difference scheme of Crank-Nicolson type. Velocity, temperature and concentration of the flow have been presented for various parameters such as thermal Grashof number, mass Grashof number, Prandtl number, Schmidt number, radiation parameter and magnetic parameter. The local and average skin friction, Nusslet number and Sherwood number are also presented graphically. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer. .

Quasi One-Dimensional Model of Natural Draft Wet-Cooling Tower Flow, Heat and Mass Transfer

Directory of Open Access Journals (Sweden)

Hyhlík Tomáš

2015-01-01

Full Text Available The article deals with the development of CFD (Computational Fluid Dynamics model of natural draft wet-cooling tower flow, heat and mass transfer. The moist air flow is described by the system of conservation laws along with additional equations. Moist air is assumed to be homogeneous mixture of dry air and water vapour. Liquid phase in the fill zone is described by the system of ordinary differential equations. Boundary value problem for the system of conservation laws is discretized in space using Kurganov-Tadmor central scheme and in time using strong stability preserving Runge-Kutta scheme. Initial value problems in the fill zone is solved by using standard fourth order Runge-Kutta scheme. The interaction between liquid water and moist air is done by source terms in governing equations.

Soil CO2 emissions as a proxy for heat and mass flow assessment, Taupō Volcanic Zone, New Zealand

Science.gov (United States)

Bloomberg, S.; Werner, Cynthia A.; Rissmann, C.F.; Mazot, A.; Horton, Travis B.; Gravley, D; Kennedy, B.; Oze, C

2014-01-01

The quantification of heat and mass flow between deep reservoirs and the surface is important for understanding magmatic and hydrothermal systems. Here, we use high-resolution measurement of carbon dioxide flux (φCO2) and heat flow at the surface to characterize the mass (CO2 and steam) and heat released to the atmosphere from two magma-hydrothermal systems. Our soil gas and heat flow surveys at Rotokawa and White Island in the Taupō Volcanic Zone, New Zealand, include over 3000 direct measurements of φCO2 and soil temperature and 60 carbon isotopic values on soil gases. Carbon dioxide flux was separated into background and magmatic/hydrothermal populations based on the measured values and isotopic characterization. Total CO2 emission rates (ΣCO2) of 441 ± 84 t d−1 and 124 ± 18 t d−1were calculated for Rotokawa (2.9 km2) and for the crater floor at White Island (0.3 km2), respectively. The total CO2 emissions differ from previously published values by +386 t d−1 at Rotokawa and +25 t d−1 at White Island, demonstrating that earlier research underestimated emissions by 700% (Rotokawa) and 25% (White Island). These differences suggest that soil CO2 emissions facilitate more robust estimates of the thermal energy and mass flux in geothermal systems than traditional approaches. Combining the magmatic/hydrothermal-sourced CO2 emission (constrained using stable isotopes) with reservoir H2O:CO2mass ratios and the enthalpy of evaporation, the surface expression of thermal energy release for the Rotokawa hydrothermal system (226 MWt) is 10 times greater than the White Island crater floor (22.5 MWt).

Creditor rights, country governance, and corporate cash holdings

NARCIS (Netherlands)

Seifert, Bruce; Gonenc, Halit

2016-01-01

This study examines the impact of creditor rights and country governance on cash holdings using a sample of firms from 47 countries. We hypothesize that cash holdings are smaller when both creditor rights and country governance are high. In these circumstances firms will not need to hold as much

Radiation effects on flow past an impulsively started vertical plate with variable temperature and mass flux

Directory of Open Access Journals (Sweden)

Muthucumaraswamy R.

2005-01-01

Full Text Available An analysis is performed to study the thermal radiation effects on unsteady free convective flow over a moving vertical plate in the presence of variable temperature and uniform mass flux. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The temperature is raised linearly with time and the concentration level near the plate are raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity and skinfriction are studied for different parameters like the radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing radiation parameter.

Body Growth and Rapid Hematological Development Support Breath Hold of Baby Belugas (Delphinapterus leucas) during Subice Transit.

Science.gov (United States)

Noren, Shawn R; Poll, Caryn P; Edwards, Matthew S

Body size and oxygen stores in the blood and muscle set breath-hold limits in marine mammals, yet these characteristics are understudied in immature cetaceans. We examined body mass and hematology from birth through adulthood in beluga whales (Delphinapterus leucas). At birth, body mass was 8% and 6% of the maximum mass recorded for adult females and males, respectively. Body mass then increased rapidly, approaching an asymptote around 12 yr for females and 18 yr for males. Interestingly, red blood cell counts, hemoglobin content, and hematocrit levels decreased after birth; this neonatal anemia was reversed as levels increased after 2 mo postpartum. Mature levels were obtained at approximately 8, 9, and 11 mo postpartum, respectively. Neonatal mean corpuscular hemoglobin also increased with ontogeny; mature levels were achieved by approximately 13 mo after birth. In contrast, mean corpuscular volume and mean corpuscular hemoglobin concentration demonstrated a significant but subtle increase throughout ontogeny. Our results indicate that postnatal maturation was required and that maturation occurred far earlier than the age at weaning (i.e., 2-3 yr postpartum). This is atypical of marine mammals, which generally achieve mature hemoglobin levels at weaning. Hematological maturation before maternal independence undoubtedly supports the prolonged breath holds of young belugas transiting under sea ice. This assessment enhances our knowledge of cetacean physiology and provides important inputs for determining age-specific dive capacity, yielding insights into age-specific flexibility to alter underwater behaviors, as will be required for future regime shifts and disturbances.

Estimation of the quantification uncertainty from flow injection and liquid chromatography transient signals in inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Laborda, Francisco; Medrano, Jesus; Castillo, Juan R.

2004-01-01

The quality of the quantitative results obtained from transient signals in high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) and flow injection-inductively coupled plasma mass spectrometry (FI-ICPMS) was investigated under multielement conditions. Quantification methods were based on multiple-point calibration by simple and weighted linear regression, and double-point calibration (measurement of the baseline and one standard). An uncertainty model, which includes the main sources of uncertainty from FI-ICPMS and HPLC-ICPMS (signal measurement, sample flow rate and injection volume), was developed to estimate peak area uncertainties and statistical weights used in weighted linear regression. The behaviour of the ICPMS instrument was characterized in order to be considered in the model, concluding that the instrument works as a concentration detector when it is used to monitorize transient signals from flow injection or chromatographic separations. Proper quantification by the three calibration methods was achieved when compared to reference materials, although the double-point calibration allowed to obtain results of the same quality as the multiple-point calibration, shortening the calibration time. Relative expanded uncertainties ranged from 10-20% for concentrations around the LOQ to 5% for concentrations higher than 100 times the LOQ

An experimental and numerical study of the flow and mass transfer in a model of the wearable artificial kidney dialyzer

Directory of Open Access Journals (Sweden)

Rosenfeld Moshe

2010-05-01

Full Text Available Abstract Background Published studies of the past decades have established that mass transfer across the dialyzer membrane is governed by diffusion, convection and osmosis. While the former is independent of the pressure in the liquids, the latter two are pressure dependent and are enhanced when the pressure difference across the membrane is increased. The goal of the present study is to examine the impact of pulsatile flow on the transport phenomena across the membrane of a high-flux dialyzer in a wearable artificial kidney (WAK with a novel single small battery-operated pulsatile pump that drives both the blood and dialysate in a counter-phased manner, maximizing the trans-membrane pressure. Methods Both in-vitro experimental and numerical tools are employed to compare the performance of the pulsatile WAK dialyzer with a traditional design of a single-channel roller blood pump together with a centrifugal pump that drives the dialysate flow. The numerical methods utilize the axisymmetric Navier-Stokes and mass transfer equations to model the flow in the fibers of the dialyzer. Results While diffusion is still the dominating transport regime, the WAK pump enhances substantially the trans-membrane pressure and thus increases mass convection that might be as high as 30% of the overall transfer. This increase is obtained due to the design of the pulsatile WAK pump that increases ultrafiltration by increasing the trans-membrane pressure. Conclusions The experimental and numerical results revealed that when pumping at similar flow rates, a small battery-operated pulsatile pump provides clearances of urea and creatinine similar as or better than a large heavy AC-powered roller pump.

12 CFR 583.12 - Multiple savings and loan holding company.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Multiple savings and loan holding company. 583... DEFINITIONS FOR REGULATIONS AFFECTING SAVINGS AND LOAN HOLDING COMPANIES § 583.12 Multiple savings and loan holding company. The term multiple savings and loan holding company means any savings and loan holding...

12 CFR 583.11 - Diversified savings and loan holding company.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Diversified savings and loan holding company... DEFINITIONS FOR REGULATIONS AFFECTING SAVINGS AND LOAN HOLDING COMPANIES § 583.11 Diversified savings and loan holding company. The term diversified savings and loan holding company means any savings and loan holding...

12 CFR 225.81 - What is a financial holding company?

Science.gov (United States)

2010-01-01

... RESERVE SYSTEM BANK HOLDING COMPANIES AND CHANGE IN BANK CONTROL (REGULATION Y) Regulations Financial Holding Companies § 225.81 What is a financial holding company? (a) Definition. A financial holding... 12 Banks and Banking 3 2010-01-01 2010-01-01 false What is a financial holding company? 225.81...

Single breath hold 3D cardiac cine MRI using kat-ARC: preliminary results at 1.5T.

Science.gov (United States)

Jeong, Daniel; Schiebler, Mark L; Lai, Peng; Wang, Kang; Vigen, Karl K; François, Christopher J

2015-04-01

Validation of a new single breath-hold, three-dimensional, cine balanced steady-state free precession (3D cine bSSFP) cardiac magnetic resonance (CMR) sequence for left ventricular function. CMR examinations were performed on fifteen patients and three healthy volunteers on a clinical 1.5T scanner using a two-dimensional (2D) cine balanced SSFP CMR sequence (2D cine bSSFP) followed by an investigational 3D cine bSSFP pulse sequence acquired within a single breath hold. Left ventricular end diastolic volume (LVEDV), end systolic volume (LVESV), ejection fraction (LVEF), and myocardial mass were independently segmented on a workstation by two experienced radiologists. Blood pool to myocardial contrast was evaluated in consensus using a Likert scale. Bland-Altman analysis was used to compare these quantitative and nominal measurements for the two sequences. The average acquisition time was significantly shorter for the 3D cine bSSFP than for 2D cine bSSFP (0.36 ± 0.03 vs. 8.5 ± 2.3 min) p = 0.0002. Bland-Altman analyses [bias and (limits of agreement)] of the data derived from these two methods revealed that the LVEF 0.9% (-4.7, 6.4), LVEDV 4.9 ml (-23.0, 32.8), LVESV -0.2 ml (-22.4, 21.9), and myocardial mass -0.4 g (-23.8, 23.0) were not significantly different. There was excellent intraclass correlation for intra-observer variability (0.981, 0.989, 0.997, 0.985) and inter-observer variability (0.903, 0.954, 0.970, 0.842) for LVEF, LVEDV, LVESV, and myocardial mass respectively. 3D cine bSSFP allows for accurate single breath-hold volumetric cine CMR which enables substantial improvements in scanner time efficiency without sacrificing diagnostic accuracy.

“Veillant Panoptic Assemblage”: Mutual Watching and Resistance to Mass Surveillance after Snowden

Directory of Open Access Journals (Sweden)

Vian Bakir

2015-10-01

Full Text Available The Snowden leaks indicate the extent, nature, and means of contemporary mass digital surveillance of citizens by their intelligence agencies and the role of public oversight mechanisms in holding intelligence agencies to account. As such, they form a rich case study on the interactions of “veillance” (mutual watching involving citizens, journalists, intelligence agencies and corporations. While Surveillance Studies, Intelligence Studies and Journalism Studies have little to say on surveillance of citizens’ data by intelligence agencies (and complicit surveillant corporations, they offer insights into the role of citizens and the press in holding power, and specifically the political-intelligence elite, to account. Attention to such public oversight mechanisms facilitates critical interrogation of issues of surveillant power, resistance and intelligence accountability. It directs attention to the veillant panoptic assemblage (an arrangement of profoundly unequal mutual watching, where citizens’ watching of self and others is, through corporate channels of data flow, fed back into state surveillance of citizens. Finally, it enables evaluation of post-Snowden steps taken towards achieving an equiveillant panoptic assemblage (where, alongside state and corporate surveillance of citizens, the intelligence-power elite, to ensure its accountability, faces robust scrutiny and action from wider civil society.

Effects of holding pressure and process temperatures on the mechanical properties of moulded metallic parts

DEFF Research Database (Denmark)

Islam, Aminul; Hansen, Hans Nørgaard; Esteves, N.M.

2013-01-01

Metal injection moulding is gaining more and more importance over the time and needs more research to be done to understand the sensitivity of process to different process parameters. The current paper makes an attempt to better understand the effects of holding pressure and process temperatures...... on the moulded metallic parts. Stainless steel 316L is used in the investigation to produce the specimen by metal injection moulding (MIM) and multiple analyses were carried out on samples produced with different combinations of holding pressure, mould temperature and melt temperature. Finally, the parts were...... characterized to investigate mechanical properties like density, ultimate tensile strength, shrinkage etc. The results are discussed in the paper. The main conclusion from this study is unlike plastic moulding, the tensile properties of MIM parts doesn’t vary based on the flow direction of the melt, and tensile...

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.

Energy efficiency improvements utilising mass flow control and a ring topology in a district heating network

International Nuclear Information System (INIS)

Laajalehto, Tatu; Kuosa, Maunu; Mäkilä, Tapio; Lampinen, Markku; Lahdelma, Risto

2014-01-01

Heating and cooling have a major role in the energy sector, covering 46% of total final energy use worldwide. District heating (DH) is a significant technology for improving the energy efficiency of heating systems in communities, because it enables waste heat sources to be utilised economically and therefore significantly reduces the environmental impacts of power generation. As a result of new and more stringent construction regulations for buildings, the heat demands of individual buildings are decreasing and more energy-efficient heating systems have to be developed. In this study, the energy efficiency of a new DH system which includes both a new control system called mass flow control and a new network design called a ring network is examined. A topology in the Helsinki region is studied by using a commercial DH network modelling tool, Grades Heating. The district heating network is attached to a wood-burning heat station which has a heat recovery system in use. Examination is performed by means of both technical and economic analysis. The new non-linear temperature programme that is required is adopted for supply and return temperatures, which allows greater temperature cooling and smaller flow rates. Lower district heating water temperatures are essential when reducing the heat losses in the network and heat production. Mass flow control allows smaller pressure drops in the network and thus reduces the pumping power. The aim of this study was to determine the most energy-efficient DH water supply temperatures in the case network. If the ring network design is utilised, the district heating system is easier to control. As a result the total heat consumption within the heating season is reduced compared to traditional DH systems. On the basis of the results, the new DH system is significantly more energy-efficient in the case network that was examined than the traditional design. For example, average energy losses within the constraints (which consist of heat

Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

Science.gov (United States)

Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

2017-10-01

3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

Effect of Process Parameters on Flow Length and Flash Formation in Injection Moulding of High Aspect Ratio Polymeric Micro Features

Directory of Open Access Journals (Sweden)

Abdelkhalik Eladl

2018-01-01

Full Text Available This paper reports an investigation of the effects of process parameters on the quality characteristics of polymeric parts produced by micro injection moulding (μIM with two different materials. Four injection moulding process parameters (injection velocity, holding pressure, melt temperature and mould temperature were investigated using Polypropylene (PP and Acrylonitrile Butadiene Styrene (ABS. Three key characteristics of the mouldings were evaluated with respect to process settings and the material employed: part mass, flow length and flash formation. The experimentation employs a test part with four micro fingers with different aspect ratios (from 21 up to 150 and was carried out according to the Design of Experiments (DOE statistical technique. The results show that holding pressure and injection velocity are the most influential parameters on part mass with a direct effect for both materials. Both parameters have a similar effect on flow length for both PP and ABS at all aspect ratios and have higher effects as the feature thickness decreased below 300 μm. The study shows that for the investigated materials the injection speed and packing pressure were the most influential parameters for increasing the amount of flash formation, with relative effects consistent for both materials. Higher melt and mould temperatures settings were less influential parameters for increasing the flash amount when moulding with both materials. Of the two investigated materials, PP was the one exhibiting more flash formation as compared with ABS, when corresponding injection moulding parameters settings for both materials were considered.

Multiple job holding in rural villages and the Chinese road to development.

Science.gov (United States)

van der Ploeg, Jan Douwe; Jingzhong, Ye

2010-01-01

This paper examines some of the interrelations that exist between rural China's peasant economy and the wider economy in which it is embedded. In doing so it focuses on the circular flows that link town and countryside. Multiple job holding is strategic in this respect. The paper draws on research undertaken in a peasant village in Hebei Province. The research highlights some remarkable differences that exist between development processes in China and in other developing countries and traces these back to a combination of an enlightened rural policy and the strong linkages that exist between rural China and its urban "global factory".

Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

Energy Technology Data Exchange (ETDEWEB)

Kramer, D.

2007-03-27

This work deals with selected aspects of mass transport phenomena in PEFCs and DMFCs. Emphasis is placed on the implications originating from the occurrence of two-phase flow within these devices. Optimality of supply, distribution, and removal of the fuel, the oxidant, and the reaction products is of utmost importance for the stability, efficiency, and durability of the devices. Being a prerequisite for high current densities while maintaining sufficient voltage, mass transport optimization contributes to the development of cost effective as well as compact designs and hence competitive fuel cells. [German] Die Visualisierung und Quantifizierung von Fluessigwasseransammlungen in Polymerelektrolytmembran-Brennstoffzellen konnte mittels Neutronenradiographie erreicht werden. Dank dieser neuartigen diagnostischen Methode konnte erstmals die Fluessigwasseransammlung in den poroesen Gasdiffusionsschichten direkt nachgewiesen und quantifiziert werden. Die Kombination von Neutronenradiographie mit ortsaufgeloesten Stromdichtemessungen bzw. lokaler Impedanzspektroskopie erlaubte die Korrelation des inhomogenen Fluessigwasseranfalls mit dem lokalen elektrochemischen Leistungsverhalten. Systematische Untersuchungen an Polymerelektrolyt- und Direkt-Methanol-Brennstoffzellen verdeutlichen sowohl den Einfluss von Betriebsbedingungen als auch die Auswirkung von Materialeigenschaften auf die Ausbildung zweiphasiger Stroemungen.

Impact of collection container material and holding times on sample integrity for mercury and methylmercury in water

Energy Technology Data Exchange (ETDEWEB)

Riscassi, Ami L [ORNL; Miller, Carrie L [ORNL; Brooks, Scott C [ORNL

2014-01-01

Mercury (Hg) and methylmercury (MeHg) concentrations in streamwater can vary on short timescales (hourly or less) during storm flow and on a diel cycle; the frequency and timing of sampling required to accurately characterize these dynamics may be difficult to accomplish manually. Automated sampling can assist in sample collection; however use has been limited for Hg and MeHg analysis due to stability concerns of trace concentrations during extended storage times. We examined the viability of using automated samplers with disposable low-density polyethylene (LDPE) sample bags to collect industrially contaminated streamwater for unfiltered and filtered Hg and MeHg analysis. Specifically we investigated the effect of holding times ranging from hours to days on streamwater collected during baseflow and storm flow. Unfiltered and filtered Hg and MeHg concentrations decreased with increases in time prior to sample processing; holding times of 24 hours or less resulted in concentration changes (mean 11 7% different) similar to variability in duplicates collected manually during analogous field conditions (mean 7 10% different). Comparisons of samples collected with manual and automated techniques throughout a year for a wide range of stream conditions were also found to be similar to differences observed between duplicate grab samples. These results demonstrate automated sampling into LDPE bags with holding times of 24 hours or less can be effectively used to collect streamwater for Hg and MeHg analysis, and encourage the testing of these materials and methods for implementation in other aqueous systems where high-frequency sampling is warranted.

Measurements of local mass transfer coefficient of Flow Accelerated Corrosion at feeder outlet pipes in CANDU using Plaster of Paris method

International Nuclear Information System (INIS)

Hyuk Kwon; Dong Un Seo; Goon-Cherl Park

2005-01-01

Full text of publication follows: Flow Accelerated Corrosion (FAC) is a corrosion mechanism that results in wall thinning in piping systems and components. FAC on carbon steels in pure water has occurred in a number of industry and power plant. A pipe wall thinning due to the FAC at nuclear power plant is just reported in confined to carbon steel pipe on the secondary system which does not equip a radioactive component. Recently, at Canadian Deuterium Uranium type reactor, it is reported that the feeder lines suffer the wall thinning on the primary system to equip 380 feeder pipes. Differently from the fast FAC rate of the secondary system on PWR, FAC rate of feeder pipes on CANDU is not more than the 0.2 mm/year. Although the FAC rate of feeder pipe is relatively slow, the narrow thickness margin of 2.6089 mm is endangered sufficiently by only the slow FAC rate. The FAC is governed by the mass transfer coefficient which is determined by the flow field. To well predict the FAC rate, mass transfer coefficient should be well measured or calculated. New measurement method of mass transfer coefficient is developed to obtain the coefficient for the complex shape like feeder pipe. The method evaluated the naphthalene sublimation method to apply it under the water flow. The naphthalene sublimation method can be used to study mass and heat transfer with confidence for a variety of applications, but with certain restrictions. At present, Plaster of paris method can modified the sublimation method to overcome the restrictions. This method is particularly useful in complex flows on geometries and for flows with large gradients in wall transport rate. The test specimen can be easily prepared by several methods, including dipping, machining, spraying, and casting. The local transfer coefficients can be determined with high accuracy and in detail by automated measurement systems that eliminate most human errors during the measurement process. To evaluate the method, the

Energy performance of an innovative liquid desiccant dehumidification system with a counter-flow heat and mass exchanger using potassium formate

DEFF Research Database (Denmark)

Jradi, Muhyiddine; Riffat, Saffa

2014-01-01

An innovative micro-scale liquid desiccant dehumidification system is numerically investigated. The liquid desiccant dehumidification unit employs a counter-flow low-cost and efficient heat and mass exchange core, improving the thermal performance and eliminating desiccant carryover...... that the dehumidifier effectiveness is directly proportional to the intake air temperature, intake air relative humidity and liquid desiccant flow rate where the effectiveness is inversely proportional to the intake air velocity and the heat exchanger air channel height....

INNOVATION DEVELOPMENT MANAGEMENT IN VERTICALLY INTEGRATED HOLDING COMPANY

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