Determining Coolant Flow Rate Distribution In The Fuel-Modified TRIGA Plate Reactor

NASA Astrophysics Data System (ADS)

Puji Hastuti, Endiah; Widodo, Surip; Darwis Isnaini, M.; Geni Rina, S.; Syaiful, B.

2018-02-01

TRIGA 2000 reactor in Bandung is planned to have the fuel element replaced, from cylindrical uranium and zirconium-hydride (U-ZrH) alloy to U3Si2-Al plate type of low enriched uranium of 19.75% with uranium density of 2.96 gU/cm3, while the reactor power is maintained at 2 MW. This change is planned to anticipate the discontinuity of TRIGA fuel element production. The selection of this plate-type fuel element is supported by the fact that such fuel type has been produced in Indonesia and used in MPR-30 safely since 2000. The core configuration of plate-type-fuelled TRIGA reactor requires coolant flow rate through each fuel element channel in order to meet its safety function. This paper is aimed to describe the results of coolant flow rate distribution in the TRIGA core that meets the safety function at normal operation condition, physical test, shutdown, and at initial event of loss of coolant flow due power supply interruption. The design analysis to determine coolant flow rate in this paper employs CAUDVAP and COOLODN computation code. The designed coolant flow rate that meets the safety criteria of departure from nucleate boiling ratio (DNBR), onset of flow instability ratio (OFIR), and ΔΤ onset of nucleate boiling (ONB), indicates that the minimum flow rate required to cool the plate-type fuelled TRIGA core at 2 MW is 80 kg/s. Therefore, it can be concluded that the operating limitation condition (OLC) for the minimum flow rate is 80 kg/s; the 72 kg/s is to cool the active core; while the minimum flow rate for coolant flow rate drop is limited to 68 kg/s with the coolant inlet temperature 35°C. This thermohydraulic design also provides cooling for 4 positions irradiation position (IP) utilization and 1 central irradiation position (CIP) with end fitting inner diameter (ID) of 10 mm and 20 mm, respectively.

Design and test of porous-tungsten mercury vaporizers

NASA Technical Reports Server (NTRS)

Kerslake, W. R.

1972-01-01

Future use of large size Kaufman thrusters and thruster arrays will impose new design requirements for porous plug type vaporizers. Larger flow rate coupled with smaller pores to prevent liquid intrusion will be desired. The results of testing samples of porous tungsten for flow rate, liquid intrusion pressure level, and mechanical strength are presented. Nitrogen gas was used in addition to mercury flow for approximate calibration. Liquid intrusion pressure levels will require that flight thruster systems with long feed lines have some way (a valve) to restrict dynamic line pressures during launch.

Improvements to a Flow Sensor for Liquid Bismuth-Fed Hall Thrusters

NASA Technical Reports Server (NTRS)

Bonds, Kevin; Polzin, Kurt A.

2010-01-01

Recently, there has been significant interest in using bismuth metal as a propellant in Hall Thrusters [1, 2]. Bismuth offers some considerable cost, weight, and space savings over the traditional propellant--xenon. Quantifying the performance of liquid metal-fed Hall thrusters requires a very precise measure of the low propellant flow rates [1, 2]. The low flow rates (10 mg/sec) and the temperature at which free flowing liquid bismuth exists (above 300 C) preclude the use of off-the-shelf flow sensing equipment [3]. Therefore a new type of sensor is required. The hotspot bismuth flow sensor, described in Refs. [1-5] is designed to perform a flow rate measurement by measuring the velocity at which a thermal feature moves through a flow chamber. The mass flow rate can be determined from the time of flight of the thermal peak, [4, 5]. Previous research and testing has been concerned mainly with the generation of the thermal peak and it's subsequent detection. In this paper, we present design improvements to the sensor concept; and the results of testing conducted to verify the functionality of these improvements. A ceramic material is required for the sensor body (see Fig. 1), which must allow for active heating of the bismuth flow channel to keep the propellant in a liquid state. The material must be compatible with bismuth and must be bonded to conductive elements to allow for conduction of current into the liquid metal and measurement of the temperature in the flow. The new sensor requires fabrication techniques that will allow for a very small diameter flow chamber, which is required to produce useful measurements. Testing of various materials has revealed several that are potentially compatible with liquid bismuth. Of primary concern in the fabrication and testing of a robust, working prototype, is the compatibility of the selected materials with one another. Specifically, the thermal expansion rates of the materials relative to the ceramic body cannot expand so much as to cause cracks in the body or cause the bond between parts to delaminate. Those parts that will carry the current pulse must be electrically conductive while the sensor body must be an electrical insulator. Generally, the material choices as well as the sensor design must aid to preserve the integrity of the thermal feature to obtain accurate measurements. The present aim is to also incorporate, into the sensor body, an active heating arrangement based on ceramic heater technology similar to that used in semiconductor manufacturing.

40 CFR 63.9920 - What are my continuous monitoring requirements?

Code of Federal Regulations, 2012 CFR

2012-07-01

... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

40 CFR 63.9920 - What are my continuous monitoring requirements?

Code of Federal Regulations, 2013 CFR

2013-07-01

... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

40 CFR 63.9920 - What are my continuous monitoring requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

Raising the sauropod neck: it costs more to get less

PubMed Central

Seymour, Roger S.

2009-01-01

The long necks of gigantic sauropod dinosaurs are commonly assumed to have been used for high browsing to obtain enough food. However, this analysis questions whether such a posture was reasonable from the standpoint of energetics. The energy cost of circulating the blood can be estimated accurately from two physiological axioms that relate metabolic rate, blood flow rate and arterial blood pressure: (i) metabolic rate is proportional to blood flow rate and (ii) cardiac work rate is proportional to the product of blood flow rate and blood pressure. The analysis shows that it would have required the animal to expend approximately half of its energy intake just to circulate the blood, primarily because a vertical neck would have required a high systemic arterial blood pressure. It is therefore energetically more feasible to have used a more or less horizontal neck to enable wide browsing while keeping blood pressure low. PMID:19364714

Raising the sauropod neck: it costs more to get less.

PubMed

Seymour, Roger S

2009-06-23

The long necks of gigantic sauropod dinosaurs are commonly assumed to have been used for high browsing to obtain enough food. However, this analysis questions whether such a posture was reasonable from the standpoint of energetics. The energy cost of circulating the blood can be estimated accurately from two physiological axioms that relate metabolic rate, blood flow rate and arterial blood pressure: (i) metabolic rate is proportional to blood flow rate and (ii) cardiac work rate is proportional to the product of blood flow rate and blood pressure. The analysis shows that it would have required the animal to expend approximately half of its energy intake just to circulate the blood, primarily because a vertical neck would have required a high systemic arterial blood pressure. It is therefore energetically more feasible to have used a more or less horizontal neck to enable wide browsing while keeping blood pressure low.

Volume requirements for aerated mud drilling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, B.; Rajtar, J.M.

1995-09-01

Aerated mud drilling has been recognized as having many advantages over conventional mud drilling, such ass higher penetration rate, less formation damage, minimized lost circulation, and lower drilling cost. In some areas, the use of aerated mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. Maintaining an optimum combination of liquid and air flow rates is important in aerated drilling operations. However, most drilling operators are unclear on what constitutes the ``optimum combination of the liquid and air flow rates.`` Guo et al. presented a mathematical approach to determining the flowing bottomhole pressuremore » (BHP) for aerated mud drilling. This paper addresses the use of Guo et al.`s mathematical model to determine liquid and air volume requirements considering wellbore stability, pipe sticking, and formation damage as well as the cuttings-carry capacity of the aerated mud. For a formation-damage-prevention point of view, the liquid fraction in the fluid stream should e as low as possible. However, a sufficient mud flow rate is always required to make the hole stable and to maintain the cuttings-carrying capacity of the aerated mud without injecting much air volume. This paper provides a simple approach to determining the liquid and air volume requirements for aerated mud drilling.« less

Modeling the hydrodynamic and electrochemical efficiency of semi-solid flow batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunini, VE; Chiang, YM; Carter, WC

2012-05-01

A mathematical model of flow cell operation incorporating hydrodynamic and electrochemical effects in three dimensions is developed. The model and resulting simulations apply to recently demonstrated high energy-density semi-solid flow cells. In particular, state of charge gradients that develop during low flow rate operation and their effects on the spatial non-uniformity of current density within flow cells are quantified. A one-dimensional scaling model is also developed and compared to the full three-dimensional simulation. The models are used to demonstrate the impact of the choice of electrochemical couple on flow cell performance. For semi-solid flow electrodes, which can use solid activemore » materials with a wide variety of voltage-capacity responses, we find that cell efficiency is maximized for electrochemical couples that have a relatively flat voltage vs. capacity curve, operated under slow flow conditions. For example, in flow electrodes limited by macroscopic charge transport, an LiFePO4-based system requires one-third the polarization to reach the same cycling rate as an LiCoO2-based system, all else being equal. Our conclusions are generally applicable to high energy density flow battery systems, in which flow rates can be comparatively low for a given required power. (C) 2012 Elsevier Ltd. All rights reserved.« less

Design, Development, and Testing of a Water Vapor Exchanger for Spacecraft Life Support Systems

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Micka, Daniel J.; Chepko, Ariane B.; Rule, Kyle C.; Anderson, Molly S.

2016-01-01

Thermal and environmental control systems for future exploration spacecraft must meet challenging requirements for efficient operation and conservation of resources. Maximizing the use of regenerative systems and conserving water are critical considerations. This paper describes the design, development, and testing of an innovative water vapor exchanger (WVX) that can minimize the amount of water absorbed in, and vented from, regenerative CO2 removal systems. Key design requirements for the WVX are high air flow capacity (suitable for a crew of six), very high water recovery, and very low pressure losses. We developed fabrication and assembly methods that enable high-efficiency mass transfer in a uniform and stable array of Nafion tubes. We also developed analysis and design methods to compute mass transfer and pressure losses. We built and tested subscale units sized for flow rates of 2 and 5 cu ft/min (3.4–8.5 cu m/hr). Durability testing demonstrated that a stable core geometry was sustained over many humid/dry cycles. Pressure losses were very low (less than 0.5 in. H2O (125 Pa) total) and met requirements at prototypical flow rates. We measured water recovery efficiency across a range of flow rates and humidity levels that simulate the range of possible cabin conditions. We measured water recovery efficiencies in the range of 80 to 90%, with the best efficiency at lower flow rates and higher cabin humidity levels. We compared performance of the WVX with similar units built using an unstructured Nafion tube bundle. The WVX achieves higher water recovery efficiency with nearly an order of magnitude lower pressure drop than unstructured tube bundles. These results show that the WVX provides uniform flow through flow channels for both the humid and dry streams and can meet requirements for service on future exploration spacecraft. The WVX technology will be best suited for long-duration exploration vehicles that require regenerative CO2 removal systems while needing to conserve water.

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wenzhong; Yi, Ji; Chen, Siyu

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (smallmore » ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.« less

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

PubMed Central

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F.

2015-01-01

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length. PMID:26328984

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length.

PubMed

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F

2015-09-01

Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as -0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31 μl/min among four wild-type rats. The authors' measured flow rates were consistent with results in the literature. By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.

Endoscopical determination of gastric mucosal blood flow by the crossed thermocouple method.

PubMed

Hiramatsu, A; Watanabe, T; Okuhira, M; Uchiyama, S; Mizuno, T; Sameshima, Y

1984-06-01

A crossed thermocouple method in combination with endoscopy was applied to determine the blood flow rate of the human gastric mucosa. Determination was carried out with 11 healthy control subjects at 8 sites of the stomach. The blood flow rates at all sites in the corpus were found to be higher than those at the antrum. In subjects less than 50 years old the blood flow rate in the corpus was higher than in older subjects. These results were in agreed well with those obtained by the hydrogen gas clearance method, which is widely adopted clinically. The crossed thermocouple method is easily applicable to all sites in the gastric mucosa and the time required for the assay is very short. This method dose not require the inhalation of hydrogen gas which is necessary for the hydrogen gas clearance method and which is possibly harmful to humans. Although the values obtained by the crossed thermocouple method are relative to the value at a certain fixed site, this method will holds great potential for the determination of gastric mucosal blood flow rate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oktamuliani, Sri, E-mail: srioktamuliani@ymail.com; Su’ud, Zaki, E-mail: szaki@fi.itb.ac.id

A preliminary study designs SPINNOR (Small Power Reactor, Indonesia, No On-Site Refueling) liquid metal Pb-Bi cooled fast reactors, fuel (U, Pu)N, 150 MWth have been performed. Neutronic calculation uses SRAC which is designed cylindrical core 2D (R-Z) 90 × 135 cm, on the core fuel composed of heterogeneous with percentage difference of PuN 10, 12, 13% and the result of calculation is effective neutron multiplication 1.0488. Power density distribution of the output SRAC is generated for thermal hydraulic calculation using Delphi based on Pascal language that have been developed. The research designed a reactor that is capable of natural circulation atmore » inlet temperature 300 °C with variation of total mass flow rate. Total mass flow rate affect pressure drop and temperature outlet of the reactor core. The greater the total mass flow rate, the smaller the outlet temperature, but increase the pressure drop so that the chimney needed more higher to achieve natural circulation or condition of the system does not require a pump. Optimization of the total mass flow rate produces optimal reactor design on the total mass flow rate of 5000 kg/s with outlet temperature 524,843 °C but require a chimney of 6,69 meters.« less

40 CFR 91.417 - Fuel flow measurement specifications.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have a...

A Low-Erosion Starting Technique for High-Performance Arcjets

NASA Technical Reports Server (NTRS)

Sankovic, John M.; Curran, Francis M.

1994-01-01

The NASA arcjet program is currently sponsoring development of high specific impulse thrusters for next generation geosynchronous communications satellites (2 kW-class) and low-power arcjets for power limited spacecraft (approx. 0.5 kW-class). Performance goals in both of these efforts will require up to 1000 starts at propellant mass flow rates significantly below those used in state-of-the-art arcjet thruster systems (i.e., high specific power levels). Reductions in mass flow rate can lead to damaging modes of operation, particularly at thruster ignition. During the starting sequence, the gas dynamic force due to low propellant flow is often insufficient to rapidly push the arc anode attachment to its steady-state position in the diverging section of the nozzle. This paper describes the development and demonstration of a technique which provides for non-damaging starts at low steady-state flow rates. The technique employs a brief propellant pressure pulse at ignition to increase gas dynamic forces during the critical ignition/transition phase of operation. Starting characteristics obtained using both pressure-pulsed and conventional starting techniques were compared across a wide range of propellant flow rates. The pressure-pulsed starting technique provided reliable starts at mass flow rates down to 21 mg/s, typically required for 700 s specific impulse level operation of 2 kW thrusters. Following the comparison, a 600 start test was performed across a wide flow rate range. Post-test inspection showed minimal erosion of critical arcjet anode/nozzle surfaces.

40 CFR 264.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

...., temperatures, flow rates, or vent stream organic compounds and concentrations) that represent the conditions... the estimated or design flow rate and organic content of each vent stream and define the acceptable..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 264.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

...., temperatures, flow rates, or vent stream organic compounds and concentrations) that represent the conditions... the estimated or design flow rate and organic content of each vent stream and define the acceptable..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 264.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

...., temperatures, flow rates, or vent stream organic compounds and concentrations) that represent the conditions... the estimated or design flow rate and organic content of each vent stream and define the acceptable..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 265.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

...., temperatures, flow rates or vent stream organic compounds and concentrations) that represent the conditions... -include the estimated or design flow rate and organic content of each vent stream and define the..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 265.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

...., temperatures, flow rates or vent stream organic compounds and concentrations) that represent the conditions... -include the estimated or design flow rate and organic content of each vent stream and define the..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 264.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

...., temperatures, flow rates, or vent stream organic compounds and concentrations) that represent the conditions... the estimated or design flow rate and organic content of each vent stream and define the acceptable..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 265.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

...., temperatures, flow rates or vent stream organic compounds and concentrations) that represent the conditions... -include the estimated or design flow rate and organic content of each vent stream and define the..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

40 CFR 265.1035 - Recordkeeping requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

...., temperatures, flow rates or vent stream organic compounds and concentrations) that represent the conditions... -include the estimated or design flow rate and organic content of each vent stream and define the..., drawings, schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI...

Development of braided rope seals for hypersonic engine applications: Flow modeling

NASA Technical Reports Server (NTRS)

Mutharasan, Rajakkannu; Steinetz, Bruce M.; Tao, Xiaoming; Du, Guang-Wu; Ko, Frank

1992-01-01

A new type of engine seal is being developed to meet the needs of advanced hypersonic engines. A seal braided of emerging high temperature ceramic fibers comprised of a sheath-core construction was selected for study based on its low leakage rates. Flexible, low-leakage, high temperature seals are required to seal the movable engine panels of advanced ramjet-scramjet engines either preventing potentially dangerous leakage into backside engine cavities or limiting the purge coolant flow rates through the seals. To predict the leakage through these flexible, porous seal structures new analytical flow models are required. Two such models based on the Kozeny-Carman equations are developed herein and are compared to experimental leakage measurements for simulated pressure and seal gap conditions. The models developed allow prediction of the gas leakage rate as a function of fiber diameter, fiber packing density, gas properties, and pressure drop across the seal. The first model treats the seal as a homogeneous fiber bed. The second model divides the seal into two homogeneous fiber beds identified as the core and the sheath of the seal. Flow resistances of each of the main seal elements are combined to determine the total flow resistance. Comparisons between measured leakage rates and model predictions for seal structures covering a wide range of braid architectures show good agreement. Within the experimental range, the second model provides a prediction within 6 to 13 percent of the flow for many of the cases examined. Areas where future model refinements are required are identified.

Pumping power considerations in the designs of NASA-Redox flow cells

NASA Technical Reports Server (NTRS)

Hoberecht, M. A.

1981-01-01

Pressure drop data for six different cell geometries of various flow port, manifold, and cavity dimensions are presented. The redox/energy/storage system uses two fully soluble redox couples as anode and cathode fluids. Both fluids are pumped through a redox cell, or stack of cells, where the electrochemical reactions take place at porous carbon felt electrodes. Pressure drop losses are therefore associated with this system due to the continuous flow of reactant solutions. The exact pressure drop within a redox flow cell is directly dependent on the flow rate as well as the various cell dimensions. Pumping power requirements for a specific set of cell operating conditions are found for various cell geometries once the flow rate and pressure drop are determined. These pumping power requirements contribute to the overall system parasitic energy losses which must be minimized, the choice of cell geometry becomes critical.

Development of advanced stability theory suction prediction techniques for laminar flow control. [on swept wings

NASA Technical Reports Server (NTRS)

Srokowski, A. J.

1978-01-01

The problem of obtaining accurate estimates of suction requirements on swept laminar flow control wings was discussed. A fast accurate computer code developed to predict suction requirements by integrating disturbance amplification rates was described. Assumptions and approximations used in the present computer code are examined in light of flow conditions on the swept wing which may limit their validity.

40 CFR 146.23 - Operating, monitoring, and reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... pressure, flow rate, and cumulative volume at least with the following frequencies: (i) Weekly for produced..., flow rate and cumulative volume at reasonable intervals no greater than 30 days. (3) A demonstration of..., and any major changes in characteristics or sources of injected fluid. Previously submitted...

77 FR 7005 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-10

... delivered fuel flow than the engine fuel flow demand needed to achieve the OEI rating at high altitude. They...-engine-inoperative (OEI) rating at altitudes above 10,000 feet. This condition could result in high... AD would require installing a placard that corresponds to the maximum permissible flight altitude...

Evaluation of Application Accuracy and Performance of a Hydraulically Operated Variable-Rate Aerial Application System

USDA-ARS?s Scientific Manuscript database

An aerial variable-rate application system consisting of a DGPS-based guidance system, automatic flow controller, and hydraulically controlled pump/valve was evaluated for response time to rapidly changing flow requirements and accuracy of application. Spray deposition position error was evaluated ...

40 CFR 63.1657 - Monitoring requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... pollution control practices that minimizes emissions per § 63.6(e)(1)(i). (c) Shop opacity. The owner or... monitoring device that continuously records the volumetric flow rate through each separately ducted hood. (3... records the volumetric flow rate at the inlet of the air pollution control device and must check and...

40 CFR 63.1657 - Monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pollution control practices that minimizes emissions per § 63.6(e)(1)(i). (c) Shop opacity. The owner or... monitoring device that continuously records the volumetric flow rate through each separately ducted hood. (3... records the volumetric flow rate at the inlet of the air pollution control device and must check and...

40 CFR 63.1657 - Monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pollution control practices that minimizes emissions per § 63.6(e)(1)(i). (c) Shop opacity. The owner or... monitoring device that continuously records the volumetric flow rate through each separately ducted hood. (3... records the volumetric flow rate at the inlet of the air pollution control device and must check and...

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642 SSV...

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642 SSV...

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642 SSV...

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642 SSV...

40 CFR 75.4 - Compliance dates.

Code of Federal Regulations, 2010 CFR

2010-07-01

... volumetric flow rate required under this part (or under the applicable State or Federal mass emissions... applicable on the deadlines specified in the applicable State or federal NOX mass emission reduction program... required by this part for monitoring SO2, NOX, CO2, opacity, moisture and volumetric flow are installed and...

Simulation of the effects of seasonally varying pumping on intraborehole flow and the vulnerability of public-supply wells to contamination

USGS Publications Warehouse

Yager, Richard M.; Heywood, Charles E.

2014-01-01

Public-supply wells with long screens in alluvial aquifers can produce waters of differing quality from different depths. Seasonal changes in quality are linked to seasonal changes in pumping rates that influence the distribution of flow into the well screens under pumping conditions and the magnitude and direction of intraborehole flow within the wells under ambient conditions. Groundwater flow and transport simulations with MODFLOW and MT3DMS were developed to quantify the effects of changes in average seasonal pumping rates on intraborehole flow and water quality at two long-screened, public-supply wells, in Albuquerque, New Mexico and Modesto, California, where widespread pumping has altered groundwater flow patterns. Simulation results indicate that both wells produce water requiring additional treatment to maintain potable quality in winter when groundwater withdrawals are reduced because less water is derived from parts of the aquifer that contain water requiring less treatment. Simulation results indicate that the water quality at both wells could be improved by increasing average winter-pumping rates to induce more lateral flow from parts of the aquifer that contain better quality water. Arsenic-bearing water produced by the Albuquerque well could be reduced from 55% to 45% by doubling average winter-pumping rate, while nitrate- and uranium-bearing water produced by the Modesto well could be reduced from 95% to 65% by nearly tripling the average winter-pumping rate. Higher average winter-pumping rates would also reduce the volume of intraborehole flow within both wells and prevent the exchange of poor quality water between shallow and deep parts of both aquifers.

Spin coating apparatus

DOEpatents

Torczynski, John R.

2000-01-01

A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

Electro-osmotically driven liquid delivery method and apparatus

DOEpatents

Rakestraw, David J.; Anex, Deon S.; Yan, Chao; Dadoo, Rajeev; Zare, Richard N.

1999-01-01

Method and apparatus for controlling precisely the composition and delivery of liquid at sub-.mu.L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-.mu.L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column.

Adaptation of the Carter-Tracy water influx calculation to groundwater flow simulation

USGS Publications Warehouse

Kipp, Kenneth L.

1986-01-01

The Carter-Tracy calculation for water influx is adapted to groundwater flow simulation with additional clarifying explanation not present in the original papers. The Van Everdingen and Hurst aquifer-influence functions for radial flow from an outer aquifer region are employed. This technique, based on convolution of unit-step response functions, offers a simple but approximate method for embedding an inner region of groundwater flow simulation within a much larger aquifer region where flow can be treated in an approximate fashion. The use of aquifer-influence functions in groundwater flow modeling reduces the size of the computational grid with a corresponding reduction in computer storage and execution time. The Carter-Tracy approximation to the convolution integral enables the aquifer influence function calculation to be made with an additional storage requirement of only two times the number of boundary nodes more than that required for the inner region simulation. It is a good approximation for constant flow rates but is poor for time-varying flow rates where the variation is large relative to the mean. A variety of outer aquifer region geometries, exterior boundary conditions, and flow rate versus potentiometric head relations can be used. The radial, transient-flow case presented is representative. An analytical approximation to the functions of Van Everdingen and Hurst for the dimensionless potentiometric head versus dimensionless time is given.

14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.

Code of Federal Regulations, 2010 CFR

2010-01-01

... discretion. (c) If first-aid oxygen equipment is installed, the minimum mass flow of oxygen to each user may... upon an average flow rate of 3 liters per minute per person for whom first-aid oxygen is required. (d...

Decline of the performance of a portable axial-flow fan due to the friction and duct bending loss of a connected flexible duct.

PubMed

Ojima, Jun

2017-03-28

In a job site, a portable fan is often used to ventilate a confined space. When a portable fan is applied to such a space, the actual ventilation flow rate must be accurately estimated in advance because the safety level of contaminant and oxygen concentrations in the space will determine the ventilation requirements. When a portable fan is used with a flexible duct, the actual flow rate of the fan decreases due to the friction and duct bending loss of the duct. Intending to show the decline of a fan performance, the author conducted laboratory experiments and reported the quantitative effect of the friction and duct bending loss of a flexible duct to the flow rate of a portable fan. Four commercial portable fans of different specifications were procured for the experiments, and the decline of the performance of each portable fan due to the friction loss etc. of a connected flexible duct was investigated by measuring actual flow rate. The flow rate showed an obvious decrease from the rated flow rate when a flexible duct was connected. Connection of a straight polyester flexible duct and a straight aluminum flexible duct reduced the flow rates to 81.2 - 52.9% and less than 50%, respectively. The flow rate decreased with an increase of the bend angle of the flexible duct. It is recommended that flow rate check of a portable fan should be diligently carried out in every job site.

Liquid Acquisition Device Design Sensitivity Study

NASA Technical Reports Server (NTRS)

VanDyke, M. K.; Hastings, L. J.

2012-01-01

In-space propulsion often necessitates the use of a capillary liquid acquisition device (LAD) to assure that gas-free liquid propellant is available to support engine restarts in microgravity. If a capillary screen-channel device is chosen, then the designer must determine the appropriate combination screen mesh and channel geometry. A screen mesh selection which results in the smallest LAD width when compared to any other screen candidate (for a constant length) is desirable; however, no best screen exists for all LAD design requirements. Flow rate, percent fill, and acceleration are the most influential drivers for determining screen widths. Increased flow rates and reduced percent fills increase the through-the-screen flow pressure losses, which drive the LAD to increased widths regardless of screen choice. Similarly, increased acceleration levels and corresponding liquid head pressures drive the screen mesh selection toward a higher bubble point (liquid retention capability). After ruling out some screens on the basis of acceleration requirements alone, candidates can be identified by examining screens with small flow-loss-to-bubble point ratios for a given condition (i.e., comparing screens at certain flow rates and fill levels). Within the same flow rate and fill level, the screen constants inertia resistance coefficient, void fraction, screen pore or opening diameter, and bubble point can become the driving forces in identifying the smaller flow-loss-to-bubble point ratios.

Electrochemical treatment of cetrimonium chloride with boron-doped diamond anodes. A technical and economical approach.

PubMed

de Araújo, Brenda R S; Linares León, José J

2018-05-15

This study presents the results of the electrochemical degradation of the emulsifier cetrimonium chloride (CTAC) on a boron-doped diamond (BDD) anode under different current densities and flow rates. Higher values of these parameters result in a more rapid removal. Nevertheless, operation at low current reduces the required applied charge and increases the chemical oxygen demand (COD) removal efficiency, as there is less development of ineffective parasitic reactions. On the other hand, high flow rates reduce the required volumetric applied charge and increase the COD removal current efficiency. In order to assist and enrich the study, an economic analysis has been performed. For short expected plant lifespans, operation at low current is advantageous due to the lower investment required, whereas for longer expected lifespans, the operational costs make the lower current densities less costly. High flow rates are always advantageous from a financial point of view. Copyright © 2018 Elsevier Ltd. All rights reserved.

The cooling rates of pahoehoe flows: The importance of lava porosity

NASA Technical Reports Server (NTRS)

Jones, Alun C.

1993-01-01

Many theoretical models have been put forward to account for the cooling history of a lava flow; however, only limited detailed field data exist to validate these models. To accurately model the cooling of lava flows, data are required, not only on the heat loss mechanisms, but also on the surface skin development and the causes of differing cooling rates. This paper argues that the cause of such variations in the cooling rates are attributed, primarily, to the vesicle content and degassing history of the lava.

Gravity flow rate of solids through orifices and pipes

NASA Technical Reports Server (NTRS)

Gardner, J. F.; Smith, J. E.; Hobday, J. M.

1977-01-01

Lock-hopper systems are the most common means for feeding solids to and from coal conversion reactor vessels. The rate at which crushed solids flow by gravity through the vertical pipes and valves in lock-hopper systems affects the size of pipes and valves needed to meet the solids-handling requirements of the coal conversion process. Methods used to predict flow rates are described and compared with experimental data. Preliminary indications are that solids-handling systems for coal conversion processes are over-designed by a factor of 2 or 3.

30 CFR 74.4 - Specifications of sampler unit.

Code of Federal Regulations, 2012 CFR

2012-07-01

... is not required. (7) Battery. The power supply for the pump shall be a suitable battery located in... battery may be recharged without removing the battery from the pump case or from the battery case if a separate battery case is used. (11) Flow rate indicator. A visual indicator of flow rate shall be provided...

30 CFR 74.4 - Specifications of sampler unit.

Code of Federal Regulations, 2011 CFR

2011-07-01

... is not required. (7) Battery. The power supply for the pump shall be a suitable battery located in... battery may be recharged without removing the battery from the pump case or from the battery case if a separate battery case is used. (11) Flow rate indicator. A visual indicator of flow rate shall be provided...

30 CFR 74.4 - Specifications of sampler unit.

Code of Federal Regulations, 2014 CFR

2014-07-01

... is not required. (7) Battery. The power supply for the pump shall be a suitable battery located in... battery may be recharged without removing the battery from the pump case or from the battery case if a separate battery case is used. (11) Flow rate indicator. A visual indicator of flow rate shall be provided...

30 CFR 74.4 - Specifications of sampler unit.

Code of Federal Regulations, 2013 CFR

2013-07-01

... is not required. (7) Battery. The power supply for the pump shall be a suitable battery located in... battery may be recharged without removing the battery from the pump case or from the battery case if a separate battery case is used. (11) Flow rate indicator. A visual indicator of flow rate shall be provided...

The temporal evolution of the resistive pressure-gradient-driven turbulence and anomalous transport in shear flow across the magnetic field

NASA Astrophysics Data System (ADS)

Lee, Hae June; Mikhailenko, Vladmir; Mikhailenko, Vladimir

2017-10-01

The temporal evolution of the resistive pressure-gradient-driven mode in the sheared flow is investigated by employing the shearing modes approach. It reveals an essential difference in the processes, which occur in the case of the flows with velocity shearing rate less than the growth rate of the instability in the steady plasmas, and in the case of the flows with velocity shear larger than the instability growth rate in steady plasmas. It displays the physical content of the empirical ``quench rule'' which predicts the suppression of the turbulence in the sheared flows when the velocity shearing rate becomes larger than the maximum growth rate of the possible instability. We found that the distortion of the perturbations by the sheared flow with such velocity shear introduces the time dependencies into the governing equations, which prohibits the application of the eigenmodes formalism and requires the solution of the initial value problem.

The Effect of Flow Rate and Canister Geometry on the Effectiveness of Removing Carbon Dioxide with Soda Lime.

DTIC Science & Technology

1980-09-01

1969 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE... Science and Engineering 3 ABSTRACT A continuation of experiments initiated by Commander Calvin G. Miller, USN, on the effect of flow rate, flow geometry and...Salvage Department INaval Coastal Systems Center Panama City, Florida 32401 6. Commander, Naval Sea Systems Command 2 Supervisor of Diving (Code GOC

Electro-osmotically driven liquid delivery method and apparatus

DOEpatents

Rakestraw, D.J.; Anex, D.S.; Yan, C.; Dadoo, R.; Zare, R.N.

1999-08-24

Method and apparatus are disclosed for controlling precisely the composition and delivery of liquid at sub-{micro}L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-{micro}L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column. 4 figs.

Assessments of fluid friction factors for use in leak rate calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chivers, T.C.

1997-04-01

Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

Micromachined cascade virtual impactor with a flow rate distributor for wide range airborne particle classification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Yong-Ho; Maeng, Jwa-Young; Park, Dongho

2007-07-23

This letter reports a module for airborne particle classification, which consists of a micromachined three-stage virtual impactor for classifying airborne particles according to their size and a flow rate distributor for supplying the required flow rate to the virtual impactor. Dioctyl sebacate particles, 100-600 nm in diameter, and carbon particles, 0.6-10 {mu}m in diameter, were used for particle classification. The collection efficiency and cutoff diameter were examined. The measured cutoff diameters of the first, second, and third stages were 135 nm, 1.9 {mu}m, and 4.8 {mu}m, respectively.

40 CFR 63.605 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the mass flow of phosphorus-bearing feed material to the process. The monitoring system shall have an... either the mass flow of phosphorus-bearing feed material to the dryer or calciner, or the mass flow of... total mass rate in metric ton/hour of phosphorus bearing feed using a monitoring system for measuring...

40 CFR 63.605 - Monitoring requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the mass flow of phosphorus-bearing feed material to the process. The monitoring system shall have an... either the mass flow of phosphorus-bearing feed material to the dryer or calciner, or the mass flow of... total mass rate in metric ton/hour of phosphorus bearing feed using a monitoring system for measuring...

Permafrost thaw in a nested groundwater-flow system

USGS Publications Warehouse

McKenzie, Jeffery M.; Voss, Clifford I.

2013-01-01

Groundwater flow in cold regions containing permafrost accelerates climate-warming-driven thaw and changes thaw patterns. Simulation analyses of groundwater flow and heat transport with freeze/thaw in typical cold-regions terrain with nested flow indicate that early thaw rate is particularly enhanced by flow, the time when adverse environmental impacts of climate-warming-induced permafrost loss may be severest. For the slowest climate-warming rate predicted by the Intergovernmental Panel on Climate Change (IPCC), once significant groundwater flow begins, thick permafrost layers can vanish in several hundred years, but survive over 1,000 years where flow is minimal. Large-scale thaw depends mostly on the balance of heat advection and conduction in the supra-permafrost zone. Surface-water bodies underlain by open taliks allow slow sub-permafrost flow, with lesser influence on regional thaw. Advection dominance over conduction depends on permeability and topography. Groundwater flow around permafrost and flow through permafrost impact thaw differently; the latter enhances early thaw rate. Air-temperature seasonality also increases early thaw. Hydrogeologic heterogeneity and topography strongly affect thaw rates/patterns. Permafrost controls the groundwater/surface-water-geomorphology system; hence, prediction and mitigation of impacts of thaw on ecology, chemical exports and infrastructure require improved hydrogeology/permafrost characterization and understanding

Estimation of Blood Flow Rates in Large Microvascular Networks

PubMed Central

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

2012-01-01

Objective Recent methods for imaging microvascular structures provide geometrical data on networks containing thousands of segments. Prediction of functional properties, such as solute transport, requires information on blood flow rates also, but experimental measurement of many individual flows is difficult. Here, a method is presented for estimating flow rates in a microvascular network based on incomplete information on the flows in the boundary segments that feed and drain the network. Methods With incomplete boundary data, the equations governing blood flow form an underdetermined linear system. An algorithm was developed that uses independent information about the distribution of wall shear stresses and pressures in microvessels to resolve this indeterminacy, by minimizing the deviation of pressures and wall shear stresses from target values. Results The algorithm was tested using previously obtained experimental flow data from four microvascular networks in the rat mesentery. With two or three prescribed boundary conditions, predicted flows showed relatively small errors in most segments and fewer than 10% incorrect flow directions on average. Conclusions The proposed method can be used to estimate flow rates in microvascular networks, based on incomplete boundary data and provides a basis for deducing functional properties of microvessel networks. PMID:22506980

40 CFR 60.276 - Recordkeeping and reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

...; (4) Flow diagram of process and emission capture equipment including other equipment or process(es... values exceeding ±15 percent of the value established under § 60.274(c) or operation at flow rates lower...

40 CFR 60.276 - Recordkeeping and reporting requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

...; (4) Flow diagram of process and emission capture equipment including other equipment or process(es... values exceeding ±15 percent of the value established under § 60.274(c) or operation at flow rates lower...

40 CFR 60.276 - Recordkeeping and reporting requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

...; (4) Flow diagram of process and emission capture equipment including other equipment or process(es... values exceeding ±15 percent of the value established under § 60.274(c) or operation at flow rates lower...

40 CFR 60.276 - Recordkeeping and reporting requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

...; (4) Flow diagram of process and emission capture equipment including other equipment or process(es... values exceeding ±15 percent of the value established under § 60.274(c) or operation at flow rates lower...

40 CFR 60.276 - Recordkeeping and reporting requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

...; (4) Flow diagram of process and emission capture equipment including other equipment or process(es... values exceeding ±15 percent of the value established under § 60.274(c) or operation at flow rates lower...

Theory of plasma contractors for electrodynamic tethered satellite systems

NASA Technical Reports Server (NTRS)

Parks, D. E.; Katz, I.

1986-01-01

Recent data from ground and space experiments indicate that plasma releases from an object dramatically reduce the sheath impedance between the object and the ambient plasma surrounding it. Available data is in qualitative accord with the theory developed to quantify the flow of current in the sheath. Electron transport in the theory is based on a fluid model of a collisionless plasma with an effective collision frequency comparable to frequencies of plasma oscillations. The theory leads to low effective impedances varying inversely with the square root of the injected plasma density. To support such a low impedance mode of operation using an argon plasma source for example requires that only one argon ion be injected for each thirty electrons extracted from the ambient plasma. The required plasma flow rates are quite low; to extract one ampere of electron current requires a mass flow rate of about one gram of argon per day.

Navier-Stokes computation of compressible turbulent flows with a second order closure

NASA Technical Reports Server (NTRS)

Dingus, C.; Kollmann, W.

1991-01-01

The objective was the development of a complete second order closure for wall bounded flows, including all components of the dissipation rate tensor and a numerical solution procedure for the resulting system of equations. The main topics discussed are the closure of the pressure correlations and the viscous destruction terms in the dissipation rate equations and the numerical solution scheme based on a block-tridiagonal solver for the nine equations required for the prediction of plane or axisymmetric flows.

40 CFR 86.140-94 - Exhaust sample analysis.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) and (2) of this section if required. (4) Check flow rates and pressures. (5) Measure THC, CO, CO2, CH4... accomplished by either of the following methods: (i) Close heated valve in THC sample (see Figures B94-5 or B94... pressure. (ii) Connect zero and span line directly to THC sample probe and introduce gases at a flow rate...

40 CFR 86.140-94 - Exhaust sample analysis.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) and (2) of this section if required. (4) Check flow rates and pressures. (5) Measure THC, CO, CO2, CH4... accomplished by either of the following methods: (i) Close heated valve in THC sample (see Figures B94-5 or B94... pressure. (ii) Connect zero and span line directly to THC sample probe and introduce gases at a flow rate...

40 CFR 86.140-94 - Exhaust sample analysis.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) and (2) of this section if required. (4) Check flow rates and pressures. (5) Measure THC, CO, CO2, CH4... accomplished by either of the following methods: (i) Close heated valve in THC sample (see Figures B94-5 or B94... pressure. (ii) Connect zero and span line directly to THC sample probe and introduce gases at a flow rate...

Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors

NASA Astrophysics Data System (ADS)

Tun, Min Thaw; Sakaguchi, Daisaku

2016-06-01

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. It is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

Experimental feasibility of investigating acoustic waves in Couette flow with entropy and pressure gradients

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Zorumski, William E.; Rawls, John W., Jr.

1990-01-01

The feasibility is discussed for an experimental program for studying the behavior of acoustic wave propagation in the presence of strong gradients of pressure, temperature, and flow. Theory suggests that gradients effects can be experimentally observed as resonant frequency shifts and mode shape changes in a waveguide. A convenient experimental geometry for such experiments is the annular region between two co-rotating cylinders. Radial temperature gradients in a spinning annulus can be generated by differentially heating the two cylinders via electromagnetic induction. Radial pressure gradients can be controlled by varying the cylinder spin rates. Present technology appears adequate to construct an apparatus to allow independent control of temperature and pressure gradients. A complicating feature of a more advanced experiment, involving flow gradients, is the requirement for independently controlled cylinder spin rates. Also, the boundary condition at annulus terminations must be such that flow gradients are minimally disturbed. The design and construction of an advanced apparatus to include flow gradients will require additional technology development.

40 CFR 63.9920 - What are my continuous monitoring requirements?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Continuous Compliance Requirements § 63.9920 What are my continuous monitoring requirements? For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b...

40 CFR 63.9920 - What are my continuous monitoring requirements?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Continuous Compliance Requirements § 63.9920 What are my continuous monitoring requirements? For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b...

A Soft-Start Circuit for Arcjet Ignition

NASA Technical Reports Server (NTRS)

Hamley, John A.; Sankovic, John M.

1993-01-01

The reduced propellant flow rates associated with high performance arcjets have placed new emphasis on electrode erosion, especially at startup. A soft-start current profile was defined which limited current overshoot during the initial 30 to 50 ms of operation, and maintained significantly lower than the nominal arc current for the first eight seconds of operation. A 2-5 kW arcjet PPU was modified to provide this current profile, and a 500 cycle test using simulated fully decomposed hydrazine was conducted to determine the electrode erosion during startup. Electrode geometry and mass flow rates were selected based on requirements for a 600 second specific impulse mission average arcjet system. The flow rate was varied throughout the test to simulate the blow down of a flight propellant system. Electrode damage was negligible at flow rates above 33 mg/s, and minor chamfering of the constrictor occurred at flow rates of 33 to 30 mg/s, corresponding to flow rates expected in the last 40 percent of the mission. Constrictor diameter remained unchanged and the thruster remained operable at the completion of the test. The soft-start current profile significantly reduced electrode damage when compared to state of the art starting techniques.

Syringe Pump Performance Maintained with IV Filter Use During Low Flow Rate Delivery for Pediatric Patients.

PubMed

Chau, Destiny F; Vasilopoulos, Terrie; Schoepf, Miriam; Zhang, Christina; Fahy, Brenda G

2016-09-01

Complex surgical and critically ill pediatric patients rely on syringe infusion pumps for precise delivery of IV medications. Low flow rates and in-line IV filter use may affect drug delivery. To determine the effects of an in-line filter to remove air and/or contaminants on syringe pump performance at low flow rates, we compared the measured rates with the programmed flow rates with and without in-line IV filters. Standardized IV infusion assemblies with and without IV filters (filter and control groups) attached to a 10-mL syringe were primed and then loaded onto a syringe pump and connected to a 16-gauge, 16-cm single-lumen catheter. The catheter was suspended in a normal saline fluid column to simulate the back pressure from central venous circulation. The delivered infusate was measured by gravimetric methods at predetermined time intervals, and flow rate was calculated. Experimental trials for initial programmed rates of 1.0, 0.8, 0.6, and 0.4 mL/h were performed in control and filter groups. For each trial, the flow rate was changed to double the initial flow rate and was then returned to the initial flow rate to analyze pump performance for titration of rates often required during medication administration. These conditions (initial rate, doubling of initial rate, and return to initial rate) were analyzed separately for steady-state flow rate and time to steady state, whereas their average was used for percent deviation analysis. Differences between control and filter groups were assessed using Student t tests with adjustment for multiplicity (using n = 3 replications per group). Mean time from 0 to initial flow (startup delay) was <1 minute in both groups with no statistical difference between groups (P = 1.0). The average time to reach steady-state flow after infusion startup or rate changes was not statistically different between the groups (range, 0.8-5.5 minutes), for any flow rate or part of the trial (initial rate, doubling of initial rate, and return to initial rate), although the study was underpowered to detect small time differences. Overall, the mean steady-state flow rate for each trial was below the programmed flow rate with negative mean percent deviations for each trial. In the 1.0-mL/h initial rate trial, the steady-state flow rate attained was lower in the filter than the control group for the initial rate (P = 0.04) and doubling of initial rate (P = 0.04) with a trend during the return to initial rate (P = 0.06), although this same effect was not observed when doubling the initial rate trials of 0.8 or 0.6 mL/h or any other rate trials compared with the control group. With low flow rates used in complex surgical and pediatric critically ill patients, the addition of IV filters did not confer statistically significant changes in startup delay, flow variability, or time to reach steady-state flow of medications administered by syringe infusion pumps. The overall flow rate was lower than programmed flow rate with or without a filter.

Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

NASA Technical Reports Server (NTRS)

Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

1993-01-01

A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

Extreme high temperature redox kinetics in ceria: exploration of the transition from gas-phase to material-kinetic limitations

DOE PAGES

Ji, Ho-Il; Davenport, Timothy C.; Gopal, Chirranjeevi Balaji; ...

2016-07-18

The redox kinetics of undoped ceria (CeO 2-δ) are investigated by the electrical conductivity relaxation method in the oxygen partial pressure range of -4.3 ≤ log(pO 2/atm) ≤ -2.0 at 1400 °C. It is demonstrated that extremely large gas flow rates, relative to the mass of the oxide, are required in order to overcome gas phase limitations and access the material kinetic properties. Using these high flow rate conditions, the surface reaction rate constant k chem is found to obey the correlation log(k chem/cm s -1) = (0.84 ± 0.02) × log(pO 2/atm) - (0.99 ± 0.05) and increases withmore » oxygen partial pressure. This increase contrasts the known behavior of the dominant defect species, oxygen vacancies and free electrons, which decrease in concentration with increasing oxygen partial pressure. For the sample geometries employed, diffusion was too fast to be detected. At low gas flow rates, the relaxation process becomes limited by the capacity of the sweep gas to supply/remove oxygen to/from the oxide. An analytical expression is derived for the relaxation in the gas-phase limited regime, and the result reveals an exponential decay profile, identical in form to that known for a surface reaction limited process. Thus, measurements under varied gas flow rates are required to differentiate between surface reaction limited and gas flow limited behavior.« less

Extreme high temperature redox kinetics in ceria: exploration of the transition from gas-phase to material-kinetic limitations.

PubMed

Ji, Ho-Il; Davenport, Timothy C; Gopal, Chirranjeevi Balaji; Haile, Sossina M

2016-08-03

The redox kinetics of undoped ceria (CeO2-δ) are investigated by the electrical conductivity relaxation method in the oxygen partial pressure range of -4.3 ≤ log(pO2/atm) ≤ -2.0 at 1400 °C. It is demonstrated that extremely large gas flow rates, relative to the mass of the oxide, are required in order to overcome gas phase limitations and access the material kinetic properties. Using these high flow rate conditions, the surface reaction rate constant kchem is found to obey the correlation log(kchem/cm s(-1)) = (0.84 ± 0.02) × log(pO2/atm) - (0.99 ± 0.05) and increases with oxygen partial pressure. This increase contrasts the known behavior of the dominant defect species, oxygen vacancies and free electrons, which decrease in concentration with increasing oxygen partial pressure. For the sample geometries employed, diffusion was too fast to be detected. At low gas flow rates, the relaxation process becomes limited by the capacity of the sweep gas to supply/remove oxygen to/from the oxide. An analytical expression is derived for the relaxation in the gas-phase limited regime, and the result reveals an exponential decay profile, identical in form to that known for a surface reaction limited process. Thus, measurements under varied gas flow rates are required to differentiate between surface reaction limited and gas flow limited behavior.

Very high pressure liquid chromatography using core-shell particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois A; Guiochon, Georges

2014-01-17

Five methods for controlling the mobile phase flow rate for gradient elution analyses using very high pressure liquid chromatography (VHPLC) were tested to determine thermal stability of the column during rapid gradient separations. To obtain rapid separations, instruments are operated at high flow rates and high inlet pressure leading to uneven thermal effects across columns and additional time needed to restore thermal equilibrium between successive analyses. The purpose of this study is to investigate means to minimize thermal instability and obtain reliable results by measuring the reproducibility of the results of six replicate gradient separations of a nine component RPLC standard mixture under various experimental conditions with no post-run times. Gradient separations under different conditions were performed: constant flow rates, two sets of constant pressure operation, programmed flow constant pressure operation, and conditions which theoretically should yield a constant net heat loss at the column's wall. The results show that using constant flow rates, programmed flow constant pressures, and constant heat loss at the column's wall all provide reproducible separations. However, performing separations using a high constant pressure with programmed flow reduces the analysis time by 16% compared to constant flow rate methods. For the constant flow rate, programmed flow constant pressure, and constant wall heat experiments no equilibration time (post-run time) was required to obtain highly reproducible data. Copyright © 2013 Elsevier B.V. All rights reserved.

40 CFR 60.697 - Recordkeeping requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... be kept. (i) Detailed schematics, and piping and instrumentation diagrams. (ii) The dates and... flow and volatile organic compound content under varying liquid level conditions (dynamic and static... vent stream composition, constituent concentrations, flow rate, relative humidity, and temperature. The...

40 CFR 60.697 - Recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... specifications shall be kept. (i) Detailed schematics, and piping and instrumentation diagrams. (ii) The dates..., including flow and volatile organic compound content under varying liquid level conditions (dynamic and... vent stream composition, constituent concentrations, flow rate, relative humidity, and temperature. The...

40 CFR 60.697 - Recordkeeping requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... be kept. (i) Detailed schematics, and piping and instrumentation diagrams. (ii) The dates and... flow and volatile organic compound content under varying liquid level conditions (dynamic and static... vent stream composition, constituent concentrations, flow rate, relative humidity, and temperature. The...

Cooling and crystallization of lava in open channels, and the transition of Pāhoehoe Lava to 'A'ā

NASA Astrophysics Data System (ADS)

Cashman, Katharine V.; Thornber, Carl; Kauahikaua, James P.

Samples collected from a lava channel active at Kīlauea Volcano during May 1997 are used to constrain rates of lava cooling and crystallization during early stages of flow. Lava erupted at near-liquidus temperatures ( 1150 °C) cooled and crystallized rapidly in upper parts of the channel. Glass geothermometry indicates cooling by 12-14 °C over the first 2km of transport. At flow velocities of 1-2m/s, this translates to cooling rates of 22-50 °C/h. Cooling rates this high can be explained by radiative cooling of a well-stirred flow, consistent with observations of non-steady flow in proximal regions of the channel. Crystallization of plagioclase and pyroxene microlites occurred in response to cooling, with crystallization rates of 20-50% per hour. Crystallization proceeded primarily by nucleation of new crystals, and nucleation rates of 104/cm3s are similar to those measured in the 1984 open channel flow from Mauna Loa Volcano. There is no evidence for the large nucleation delays commonly assumed for plagioclase crystallization in basaltic melts, possibly a reflection of enhanced nucleation due to stirring of the flow. The transition of the flow surface morphology from pāhoehoe to 'a'ā occurred at a distance of 1.9km from the vent. At this point, the flow was thermally stratified, with an interior temperature of 1137 °C and crystallinity of 15%, and a flow surface temperature of 1100 °C and crystallinity of 45%. 'A'ā formation initiated along channel margins, where crust was continuously disrupted, and involved tearing and clotting of the flow surface. Both observations suggest that the transition involved crossing of a rheological threshold. We suggest this threshold to be the development of a lava yield strength sufficient to prevent viscous flow of lava at the channel margin. We use this concept to propose that 'a'ā formation in open channels requires both sufficiently high strain rates for continued disruption of surface crusts and sufficient groundmass crystallinity to generate a yield strength equivalent to the imposed stress. In Hawai'i, where lava is typically microlite poor on eruption, these combined requirements help to explain two common observations on 'a'ā formation: (a) 'a'ā flow fields are generated when effusion rates are high (thus promoting crustal disruption); and (b) under most eruption conditions, lava issues from the vent as pāhoehoe and changes to 'a'ā only after flowing some distance, thus permitting sufficient crystallization.

Flow processes in electric discharge drivers

NASA Technical Reports Server (NTRS)

Baganoff, D.

1975-01-01

The performance of an electric discharge shock tube is discussed from the point of view that the conditions at the sonic station are the primary controlling variables (likewise in comparing designs), and that the analysis of the flow on either side of the sonic station should be done separately. The importance of considering mass-flow rate in matching a given driver design to the downstream flow required for a particular shock-wave speed is stressed. It is shown that a driver based on the principle of liquid injection (of H2) is superior to one based on the Ludwieg tube, because of the greater mass-flow rate and the absence of a massive diaphragm.

Energy conservation with automatic flow control valves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, D.

Automatic flow control valves are offered in a wide range of sizes starting at 1/2 in. with flow rates of 0.5 gpm and up. They are also provided with materials and end connections to meet virtually any fan-coil system requirement. Among these are copper sweat type valves; ductile iron threaded valves; male/female threaded brass valves; and combination flow control/ball valves with union ends.

Criteria for choosing an intravenous infusion line intended for multidrug infusion in anaesthesia and intensive care units.

PubMed

Maiguy-Foinard, Aurélie; Genay, Stéphanie; Lannoy, Damien; Barthélémy, Christine; Lebuffe, Gilles; Debaene, Bertrand; Odou, Pascal; Décaudin, Bertrand

2017-02-01

The aims are to identify critical parameters influencing the drug mass flow rate of infusion delivery to patients during multidrug infusion and to discuss their clinical relevance. A review of literature was conducted in January 2016 using Medline, Google Scholar, ScienceDirect, Web of Science and Scopus online databases. References relating to the accuracy of fluid delivery via gravity-flow intravenous (IV) infusion systems and positive displacement pumps, components of IV administration sets, causes of flow rate variability, potential complications due to flow rate variability, IV therapies especially at low flow rates and drug compatibilities were considered relevant. Several parameters impact the delivery of drugs and fluids by IV infusion. Among them are the components of infusion systems that particularly influence the flow rate of medications and fluids being delivered. By their conception, they may generate significant start-up delays and flow rate variability. Performing multidrug infusion requires taking into account two main points: the common dead volume of drugs delivered simultaneously with potential consequences on the accuracy and amount of drug delivery and the prevention of drug incompatibilities and their clinical effects. To prevent the potentially serious effects of flow rate variability on patients, clinicians should receive instruction on the fluid dynamics of an IV administration set and so be able to take steps to minimise flow rate changes during IV therapy. Copyright © 2016 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2012 CFR

2012-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

40 CFR 60.5407 - What are the requirements for monitoring of emissions and operations from my sweetening unit...

Code of Federal Regulations, 2013 CFR

2013-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period. At least one sample per 24-hour... sampling schedule. (3) The average acid gas flow rate from the sweetening unit. You must install and operate a monitoring device to continuously measure the flow rate of acid gas. The monitoring device...

40 CFR 60.5407 - What are the requirements for monitoring of emissions and operations from my sweetening unit...

Code of Federal Regulations, 2014 CFR

2014-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period. At least one sample per 24-hour... sampling schedule. (3) The average acid gas flow rate from the sweetening unit. You must install and operate a monitoring device to continuously measure the flow rate of acid gas. The monitoring device...

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2010 CFR

2010-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2011 CFR

2011-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

Streak Imaging Flow Cytometer for Rare Cell Analysis.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Ossandon, Miguel; Prickril, Ben; Rasooly, Avraham

2017-01-01

There is a need for simple and affordable techniques for cytology for clinical applications, especially for point-of-care (POC) medical diagnostics in resource-poor settings. However, this often requires adapting expensive and complex laboratory-based techniques that often require significant power and are too massive to transport easily. One such technique is flow cytometry, which has great potential for modification due to the simplicity of the principle of optical tracking of cells. However, it is limited in that regard due to the flow focusing technique used to isolate cells for optical detection. This technique inherently reduces the flow rate and is therefore unsuitable for rapid detection of rare cells which require large volume for analysis.To address these limitations, we developed a low-cost, mobile flow cytometer based on streak imaging. In our new configuration we utilize a simple webcam for optical detection over a large area associated with a wide-field flow cell. The new flow cell is capable of larger volume and higher throughput fluorescence detection of rare cells than the flow cells with hydrodynamic focusing used in conventional flow cytometry. The webcam is an inexpensive, commercially available system, and for fluorescence analysis we use a 1 W 450 nm blue laser to excite Syto-9 stained cells with emission at 535 nm. We were able to detect low concentrations of stained cells at high flow rates of 10 mL/min, which is suitable for rapidly analyzing larger specimen volumes to detect rare cells at appropriate concentration levels. The new rapid detection capabilities, combined with the simplicity and low cost of this device, suggest a potential for clinical POC flow cytometry in resource-poor settings associated with global health.

Tracer-monitored flow titrations.

PubMed

Sasaki, Milton K; Rocha, Diogo L; Rocha, Fábio R P; Zagatto, Elias A G

2016-01-01

The feasibility of implementing tracer-monitored titrations in a flow system is demonstrated. A dye tracer is used to estimate the instant sample and titrant volumetric fractions without the need for volume, mass or peak width measurements. The approach was applied to spectrophotometric flow titrations involving variations of sample and titrant flow-rates (i.e. triangle programmed technique) or concentration gradients established along the sample zone (i.e. flow injection system). Both strategies required simultaneous monitoring of two absorbing species, namely the titration indicator and the dye tracer. Mixing conditions were improved by placing a chamber with mechanical stirring in the analytical path aiming at to minimize diffusional effects. Unlike most of flow-based titrations, the innovation is considered as a true titration, as it does not require a calibration curve thus complying with IUPAC definition. As an application, acidity evaluation in vinegars involving titration with sodium hydroxide was selected. Phenolphthalein and brilliant blue FCF were used as indicator and dye tracer, respectively. Effects of sample volume, titrand/titrant concentrations and flow rates were investigated aiming at improved accuracy and precision. Results were reliable and in agreement with those obtained by a reference titration procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

A NEW METHOD FOR ENVIRONMENTAL FLOW ASSESSMENT BASED ON BASIN GEOLOGY. APPLICATION TO EBRO BASIN.

PubMed

2018-02-01

The determination of environmental flows is one of the commonest practical actions implemented on European rivers to promote their good ecological status. In Mediterranean rivers, groundwater inflows are a decisive factor in streamflow maintenance. This work examines the relationship between the lithological composition of the Ebro basin (Spain) and dry season flows in order to establish a model that can assist in the calculation of environmental flow rates.Due to the lack of information on the hydrogeological characteristics of the studied basin, the variable representing groundwater inflows has been estimated in a very simple way. The explanatory variable used in the proposed model is easy to calculate and is sufficiently powerful to take into account all the required characteristics.The model has a high coefficient of determination, indicating that it is accurate for the intended purpose. The advantage of this method compared to other methods is that it requires very little data and provides a simple estimate of environmental flow. It is also independent of the basin area and the river section order.The results of this research also contribute to knowledge of the variables that influence low flow periods and low flow rates on rivers in the Ebro basin.

Overview on Pendeo-Epitaxy of GaN-Based Heterostructures for Novel Devices Applications

DTIC Science & Technology

2006-11-01

pendeo-epitaxy uses the metal organic chemical vapor deposition (MOCVD) technique that commonly requires ammonia (NH3) and trimethyl gallium ( TMG ...lateral growth rate and the crystallography of the side walls of the pendeo-epitaxial GaN are the growth temperature, the ammonia to TMG flow rate...pressure of 100 Torr and V:III ratio of 2600. It is known that the ammonia to TMG (V:III) molar flow rate ratio plays a major role for the lateral to

The effect of light level, CO2 flow rate, and anesthesia on the stress response of mice during CO2 euthanasia.

PubMed

Powell, Karin; Ethun, Kelly; Taylor, Douglas K

2016-09-21

Euthanasia protocols are designed to mitigate the stress experienced by animals, and an environment that induces minimal stress helps achieve that goal. A protocol that is efficient and practical in a typical animal research facility is also important. Light intensity, isoflurane, and CO2 flow rate were studied for their impact on the stress response of mice during CO2 euthanasia. Behavior was observed and scored during euthanasia and serum corticosterone was measured immediately after death. Unsurprisingly, animals euthanized with a high-flow rate of CO2 became unconscious in the least amount of time, while animals euthanized with a low-flow rate required the most time to reach unconsciousness. There was a significant increase in anxious behaviors in animals in the isoflurane group (F1,12 = 6.67, P = 0.024), the high-flow rate CO2 group (F1,12 = 10.24, P = 0.007), and bright chamber group (F1,12 = 7.27, P = 0.019). Serum corticosterone was highest in the isoflurane group (124.72 ± 83.98 ng/ml), however there was no significant difference in corticosterone levels observed for the other study variables of light and flow-rate. A darkened chamber and low CO2 flow rates help to decrease stress experienced during CO2 euthanasia, while the use of isoflurane was observed to increase the stress response during euthanasia.

The feasibility of recharge rate determinations using the steady- state centrifuge method

USGS Publications Warehouse

Nimmo, J.R.; Stonestrom, David A.; Akstin, K.C.

1994-01-01

The establishment of steady unsaturated flow in a centrifuge permits accurate measurement of small values of hydraulic conductivity (K). This method can provide a recharge determination if it is applied to an unsaturated core sample from a depth at which gravity alone drives the flow. A K value determined at the in situ water content indicates the long-term average recharge rate at a point. Tests of this approach have been made at two sites. For sandy core samples a better knowledge of the matric pressure profiles is required before a recharge rate can be determined. Fine-textured cores required new developments of apparatus and procedures, especially for making centrifuge measurements with minimal compaction of the samples. -from Authors

U.S. EPA CSO CAPSTONE REPORT: CONTROL SYSTEM OPTIMIZATION

EPA Science Inventory

An optimized combined sewer overflow (CSO) requires a storage treatment system because storm flow in the combined sewer system is intermittent and highly variable in both pollutant concentration and flow rate. Storage and treatment alternatives are strongly influenced by input...

Injection characteristics study of high-pressure direct injector for Compressed Natural Gas (CNG) using experimental and analytical method

NASA Astrophysics Data System (ADS)

Taha, Z.; Rahim, MF Abdul; Mamat, R.

2017-10-01

The injection characteristics of direct injector affect the mixture formation and combustion processes. In addition, the injector is converted from gasoline operation for CNG application. Thus measurement of CNG direct injector mass flow rate was done by independently tested a single injector on a test bench. The first case investigated the effect of CNG injection pressure and the second case evaluate the effect of pulse-width of injection duration. An analytical model was also developed to predict the mass flow rate of the injector. The injector was operated in a choked condition in both the experiments and simulation studies. In case 1, it was shown that mass flow rate through the injector is affected by injection pressure linearly. Based on the tested injection pressure of 20 bar to 60 bar, the resultant mass flow rate are in the range of 0.4 g/s to 1.2 g/s which are met with theoretical flow rate required by the engine. However, in Case 2, it was demonstrated that the average mass flow rate at short injection durations is lower than recorded in Case 1. At injection pressure of 50 bar, the average mass flow rate for Case 2 and Case 1 are 0.7 g/s and 1.1 g/s respectively. Also, the measured mass flow rate at short injection duration showing a fluctuating data in the range of 0.2 g/s - 1.3 g/s without any noticeable trends. The injector model able to predict the trend of the mass flow rate at different injection pressure but unable to track the fluctuating trend at short injection duration.

A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

NASA Astrophysics Data System (ADS)

Qiu, X.; Cherief, W.; Colombet, D.; Ayela, F.

2017-04-01

We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops.

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2012 CFR

2012-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2013 CFR

2013-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2011 CFR

2011-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

40 CFR 60.705 - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... readings, heat content determinations, flow rate measurements, and exit velocity determinations made during... mass flow measured at least every 15 minutes and averaged over the same time period of the performance... of the flow indication specified under § 60.703(a)(2)(i), § 60.703(b)(2)(i) and § 60.703(c)(1)(i), as...

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

NASA Astrophysics Data System (ADS)

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

2016-01-01

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

A site-specific slurry application technique on grassland and on arable crops.

PubMed

Schellberg, Jürgen; Lock, Reiner

2009-01-01

There is evidence that unequal slurry application on agricultural land contributes to N losses to the environment. Heterogeneity within fields demands adequate response by means of variable rate application. A technique is presented which allows site-specific application of slurry on grassland and arable land based on pre-defined application maps. The system contains a valve controlling flow rate by an on-board PC. During operation, flow rate is measured and scaled against set point values given in the application map together with the geographic position of the site. The systems worked sufficiently precise at a flow rate between 0 and 25 l s(-1) and an offset of actual slurry flow from set point values between 0.33 and 0.67 l s(-1). Long-term experimentation is required to test if site-specific application de facto reduces N surplus within fields and so significantly contributes to the unloading of N in agricultural areas.

Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Murray E.

Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to massmore » flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is expected to require six months of time, after receipt of funding. Benefits: US DOE facilities that use HEPA filters will benefit from access to the new operational measurement methods. Uncertainty and guesswork will be removed from HEPA filter operations.« less

A clinical study to compare between resting and stimulated whole salivary flow rate and pH before and after complete denture placement in different age groups

PubMed Central

Muddugangadhar, B. C.; Sangur, Rajashekar; Rudraprasad, I. V.; Nandeeshwar, D. B.; Kumar, B. H. Dhanya

2015-01-01

Purpose: This study compared the flow rate and pH of resting (unstimulated) and stimulated whole saliva before and after complete denture placement in different age groups. Materials and Methods: Fifty healthy, non-medicated edentulous individuals of different age groups requiring complete denture prostheses were selected from the outpatient department. The resting (unstimulated) and stimulated whole saliva and pH were measured at three stages i.e., i)Before complete denture placement;ii)Immediately after complete denture placement; andiii)After 2 to 3 months of complete denture placement. Saliva production was stimulated by chewing paraffin wax. pH was determined by using a digital pH meter. Results: Statistically significant differences were seen in resting(unstimulated) and stimulated whole salivary flow rate and pH obtained before, immediately after, and after 2 to 3 months of complete denture placement. No statistically significant differences were found between the different age groups in resting (unstimulated) as well as stimulated whole salivary flow rate and pH. Conclusion: Stimulated whole salivary flow rates and pH were significantly higher than resting (unstimulated) whole salivary flow rates and pH obtained before, immediately after, and after 2 to 3 months of complete denture placement. No age related variations in whole salivary flow rate and pH were observed in healthy, non-medicated individuals. Clinical Implications: The assessment of salivary flow rate, pH in different age groups is of prognostic value, which is an important aspect to be considered in the practice of removable prosthodontics. PMID:26929540

A clinical study to compare between resting and stimulated whole salivary flow rate and pH before and after complete denture placement in different age groups.

PubMed

Muddugangadhar, B C; Sangur, Rajashekar; Rudraprasad, I V; Nandeeshwar, D B; Kumar, B H Dhanya

2015-01-01

This study compared the flow rate and pH of resting (unstimulated) and stimulated whole saliva before and after complete denture placement in different age groups. Fifty healthy, non-medicated edentulous individuals of different age groups requiring complete denture prostheses were selected from the outpatient department. The resting (unstimulated) and stimulated whole saliva and pH were measured at three stages i.e., i)Before complete denture placement;ii)Immediately after complete denture placement; andiii)After 2 to 3 months of complete denture placement. Saliva production was stimulated by chewing paraffin wax. pH was determined by using a digital pH meter. Statistically significant differences were seen in resting(unstimulated) and stimulated whole salivary flow rate and pH obtained before, immediately after, and after 2 to 3 months of complete denture placement. No statistically significant differences were found between the different age groups in resting (unstimulated) as well as stimulated whole salivary flow rate and pH. Stimulated whole salivary flow rates and pH were significantly higher than resting (unstimulated) whole salivary flow rates and pH obtained before, immediately after, and after 2 to 3 months of complete denture placement. No age related variations in whole salivary flow rate and pH were observed in healthy, non-medicated individuals. The assessment of salivary flow rate, pH in different age groups is of prognostic value, which is an important aspect to be considered in the practice of removable prosthodontics.

Microspheres as resistive elements in a check valve for low pressure and low flow rate conditions.

PubMed

Ou, Kevin; Jackson, John; Burt, Helen; Chiao, Mu

2012-11-07

In this paper we describe a microsphere-based check valve integrated with a micropump. The check valve uses Ø20 μm polystyrene microspheres to rectify flow in low pressure and low flow rate applications (Re < 1). The microspheres form a porous medium in the check valve increasing fluidic resistance based on the direction of flow. Three check valve designs were fabricated and characterized to study the microspheres' effectiveness as resistive elements. A maximum diodicity (ratio of flow in the forward and reverse direction) of 18 was achieved. The pumping system can deliver a minimum flow volume of 0.25 μL and a maximum flow volume of 1.26 μL under an applied pressure of 0.2 kPa and 1 kPa, respectively. A proof-of-concept study was conducted using a pharmaceutical agent, docetaxel (DTX), as a sample drug showing the microsphere check valve's ability to limit diffusion from the micropump. The proposed check valve and pumping concept shows strong potential for implantable drug delivery applications with low flow rate requirements.

Bubble pump: scalable strategy for in-plane liquid routing.

PubMed

Oskooei, Ali; Günther, Axel

2015-07-07

We present an on-chip liquid routing technique intended for application in well-based microfluidic systems that require long-term active pumping at low to medium flowrates. Our technique requires only one fluidic feature layer, one pneumatic control line and does not rely on flexible membranes and mechanical or moving parts. The presented bubble pump is therefore compatible with both elastomeric and rigid substrate materials and the associated scalable manufacturing processes. Directed liquid flow was achieved in a microchannel by an in-series configuration of two previously described "bubble gates", i.e., by gas-bubble enabled miniature gate valves. Only one time-dependent pressure signal is required and initiates at the upstream (active) bubble gate a reciprocating bubble motion. Applied at the downstream (passive) gate a time-constant gas pressure level is applied. In its rest state, the passive gate remains closed and only temporarily opens while the liquid pressure rises due to the active gate's reciprocating bubble motion. We have designed, fabricated and consistently operated our bubble pump with a variety of working liquids for >72 hours. Flow rates of 0-5.5 μl min(-1), were obtained and depended on the selected geometric dimensions, working fluids and actuation frequencies. The maximum operational pressure was 2.9 kPa-9.1 kPa and depended on the interfacial tension of the working fluids. Attainable flow rates compared favorably with those of available micropumps. We achieved flow rate enhancements of 30-100% by operating two bubble pumps in tandem and demonstrated scalability of the concept in a multi-well format with 12 individually and uniformly perfused microchannels (variation in flow rate <7%). We envision the demonstrated concept to allow for the consistent on-chip delivery of a wide range of different liquids that may even include highly reactive or moisture sensitive solutions. The presented bubble pump may provide active flow control for analytical and point-of-care diagnostic devices, as well as for microfluidic cells culture and organ-on-chip platforms.

Multinode acoustic focusing for parallel flow cytometry

PubMed Central

Piyasena, Menake E.; Suthanthiraraj, Pearlson P. Austin; Applegate, Robert W.; Goumas, Andrew M.; Woods, Travis A.; López, Gabriel P.; Graves, Steven W.

2012-01-01

Flow cytometry can simultaneously measure and analyze multiple properties of single cells or particles with high sensitivity and precision. Yet, conventional flow cytometers have fundamental limitations with regards to analyzing particles larger than about 70 microns, analyzing at flow rates greater than a few hundred microliters per minute, and providing analysis rates greater than 50,000 per second. To overcome these limits, we have developed multi-node acoustic focusing flow cells that can position particles (as small as a red blood cell and as large as 107 microns in diameter) into as many as 37 parallel flow streams. We demonstrate the potential of such flow cells for the development of high throughput, parallel flow cytometers by precision focusing of flow cytometry alignment microspheres, red blood cells, and the analysis of CD4+ cellular immunophenotyping assay. This approach will have significant impact towards the creation of high throughput flow cytometers for rare cell detection applications (e.g. circulating tumor cells), applications requiring large particle analysis, and high volume flow cytometry. PMID:22239072

Comparative performance of fixed-film biological filters: Application of reactor theory

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.

2006-01-01

Nitrification is classified as a two-step consecutive reaction where R1 represents the rate of formation of the intermediate product NO2-N and R2 represents the rate of formation of the final product NO3-N. The relative rates of R1 and R2 are influenced by reactor type characterized hydraulically as plug-flow, plug-flow with dispersion and mixed-flow. We develop substrate conversion models for fixed-film biofilters operating in the first-order kinetic regime based on application of chemical reactor theory. Reactor type, inlet conditions and the biofilm kinetic constants Ki (h-1) are used to predict changes in NH4-N, NO2-N, NO3-N and BOD5. The inhibiting effects of the latter on R1 and R2 were established based on the ?? relation, e.g.:{A formula is presented}where BOD5,max is the concentration that causes nitrification to cease and N is a variable relating Ki to increasing BOD5. Conversion models were incorporated in spreadsheet programs that provided steady-state concentrations of nitrogen and BOD5 at several points in a recirculating aquaculture system operating with input values for fish feed rate, reactor volume, microscreen performance, make-up and recirculating flow rates. When rate constants are standardized, spreadsheet use demonstrates plug-flow reactors provide higher rates of R1 and R2 than mixed-flow reactors thereby reducing volume requirements for target concentrations of NH4-N and NO2-N. The benefit provided by the plug-flow reactor varies with hydraulic residence time t as well as the effective vessel dispersion number, D/??L. Both reactor types are capable of providing net increases in NO2-N during treatment but the rate of decrease in the mixed-flow case falls well behind that predicted for plug-flow operation. We show the potential for a positive net change in NO2-N increases with decreases in the dimensionless ratios K2, (R2 )/K1,( R1 ) and [NO2-N]/[NH4-N] and when the product K1, (R1) t provides low to moderate NH4-N conversions. Maintaining high levels of the latter reduces the effective reactor utilization rate (%) defined here as (RNavg/RNmax)100 where RNavg is the mean reactive nitrogen concentration ([NH4-N] + [NO2-N]) within the reactor, and RNmax represents the feed concentration of the same. Low utilization rates provide a hedge against unexpected increases in substrate loading and reduce water pumping requirements but force use of elevated reactor volumes. Further ?? effects on R1 and R2 can be reduced through use of a tanks-in-series versus a single mixed-flow reactor configuration and by improving the solids removal efficiency of microscreen treatment.

Chaotic mixing in microchannels via low frequency switching transverse electroosmotic flow generated on integrated microelectrodes.

PubMed

Song, Hongjun; Cai, Ziliang; Noh, Hongseok Moses; Bennett, Dawn J

2010-03-21

In this paper we present a numerical and experimental investigation of a chaotic mixer in a microchannel via low frequency switching transverse electroosmotic flow. By applying a low frequency, square-wave electric field to a pair of parallel electrodes placed at the bottom of the channel, a complex 3D spatial and time-dependence flow was generated to stretch and fold the fluid. This significantly enhanced the mixing effect. The mixing mechanism was first investigated by numerical and experimental analysis. The effects of operational parameters such as flow rate, frequency, and amplitude of the applied voltage have also been investigated. It is found that the best mixing performance is achieved when the frequency is around 1 Hz, and the required mixing length is about 1.5 mm for the case of applied electric potential 5 V peak-to-peak and flow rate 75 microL h(-1). The mixing performance was significantly enhanced when the applied electric potential increased or the flow rate of fluids decreased.

Operating characteristics of 120-millimeter-bore ball bearings at 3 million DN

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.; Bamberger, E. N.; Signer, H.

1974-01-01

A parametric study was performed with split inner-race 120-mm-bore angular-contact ball bearings at a speed of 25,000 rpm (3 million DN) at initial contact angles of 20 deg and 24 deg. Provisions were made for outer- and inner-race cooling and for injection of lubricant into the bearing through a number of radial holes in the split inner-race of the bearing. Oil flow and coolant rate to the bearing was controlled and varied for a total up to approximately 3.2 gal/min. Bearing temperature was found to decrease as the total lubricant flow to the bearing increased. However, at intermediate flow rates temperature began to increase with increasing flow. Power consumption increased with increasing flow rate. Bearing operating temperature, differences in temperatures between the inner and outer races, and bearing power consumption can be tuned to any desirable operating requirement. Cage speed increased by not more than 2 percent with increasing oil flow to the inner race.

Energy Harvesting from Fluid Flow in Water Pipelines for Smart Metering Applications

NASA Astrophysics Data System (ADS)

Hoffmann, D.; Willmann, A.; Göpfert, R.; Becker, P.; Folkmer, B.; Manoli, Y.

2013-12-01

In this paper a rotational, radial-flux energy harvester incorporating a three-phase generation principle is presented for converting energy from water flow in domestic water pipelines. The energy harvester together with a power management circuit and energy storage is used to power a smart metering system installed underground making it independent from external power supplies or depleting batteries. The design of the radial-flux energy harvester is adapted to the housing of a conventional mechanical water flow meter enabling the use of standard components such as housing and impeller. The energy harvester is able to generate up to 720 mW when using a flow rate of 20 l/min (fully opened water tab). A minimum flow rate of 3 l/min is required to get the harvester started. In this case a power output of 2 mW is achievable. By further design optimization of the mechanical structure including the impeller and magnetic circuit the threshold flow rate can be further reduced.

40 CFR 63.7741 - What are the installation, operation, and maintenance requirements for my monitors?

Code of Federal Regulations, 2010 CFR

2010-07-01

... paragraphs (a)(1)(i) through (iv) of this section. (i) Locate the flow sensor and other necessary equipment... sensor with a minimum measurement sensitivity of 2 percent of the flow rate. (iii) Conduct a flow sensor... paragraphs (a)(2)(i) through (vi) of this section. (i) Locate the pressure sensor(s) in or as close as...

40 CFR 63.7741 - What are the installation, operation, and maintenance requirements for my monitors?

Code of Federal Regulations, 2012 CFR

2012-07-01

... paragraphs (a)(1)(i) through (iv) of this section. (i) Locate the flow sensor and other necessary equipment... sensor with a minimum measurement sensitivity of 2 percent of the flow rate. (iii) Conduct a flow sensor... paragraphs (a)(2)(i) through (vi) of this section. (i) Locate the pressure sensor(s) in or as close as...

40 CFR 63.7741 - What are the installation, operation, and maintenance requirements for my monitors?

Code of Federal Regulations, 2014 CFR

2014-07-01

... paragraphs (a)(1)(i) through (iv) of this section. (i) Locate the flow sensor and other necessary equipment... sensor with a minimum measurement sensitivity of 2 percent of the flow rate. (iii) Conduct a flow sensor... paragraphs (a)(2)(i) through (vi) of this section. (i) Locate the pressure sensor(s) in or as close as...

Quantifying the combined effects of attempt rate and swimming capacity on passage through velocity barriers

USGS Publications Warehouse

Castro-Santos, T.

2004-01-01

The ability of fish to migrate past velocity barriers results from both attempt rate and swimming capacity. Here, I formalize this relationship, providing equations for estimating the proportion of a population successfully passing a barrier over a range of distances and times. These equations take into account the cumulative effect of multiple attempts, the time required to stage those attempts, and both the distance traversed on each attempt and its variability. I apply these equations to models of white sucker (Catostomus commersoni) and walleye (Stizostedion vitreum) ascending a 23-m-long flume against flows ranging from 1.5 to 4.5 m??s-1. Attempt rate varied between species, attempts, and over time and was influenced by hydraulic variables (velocity of flow and discharge). Distance of ascent was primarily influenced by flow velocity. Although swimming capacity was similar, white sucker had greater attempt rates, and consequently better passage success, than walleye. Over short distances, models for both species predict greater passage success against higher velocities owing to the associated increased attempt rate. These results highlight the importance of attraction to fish passage and the need for further investigation into the hydraulic and other environmental conditions required to simultaneously optimize both attempt rate and passage success.

Low volume flow meter

DOEpatents

Meixler, Lewis D.

1993-01-01

The low flow monitor provides a means for determining if a fluid flow meets a minimum threshold level of flow. The low flow monitor operates with a minimum of intrusion by the flow detection device into the flow. The electrical portion of the monitor is externally located with respect to the fluid stream which allows for repairs to the monitor without disrupting the flow. The electronics provide for the adjustment of the threshold level to meet the required conditions. The apparatus can be modified to provide an upper limit to the flow monitor by providing for a parallel electronic circuit which provides for a bracketing of the desired flow rate.

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

NASA Astrophysics Data System (ADS)

Mahmoudzadeh, Javid; Wlodarczyk, Marta; Cassel, Kevin

2017-11-01

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

Flow range enhancement by secondary flow effect in low solidity circular cascade diffusers

NASA Astrophysics Data System (ADS)

Sakaguchi, Daisaku; Tun, Min Thaw; Mizokoshi, Kanata; Kishikawa, Daiki

2014-08-01

High-pressure ratio and wide operating range are highly required for compressors and blowers. The technical issue of the design is achievement of suppression of flow separation at small flow rate without deteriorating the efficiency at design flow rate. A numerical simulation is very effective in design procedure, however, cost of the numerical simulation is generally high during the practical design process, and it is difficult to confirm the optimal design which is combined with many parameters. A multi-objective optimization technique is the idea that has been proposed for solving the problem in practical design process. In this study, a Low Solidity circular cascade Diffuser (LSD) in a centrifugal blower is successfully designed by means of multi-objective optimization technique. An optimization code with a meta-model assisted evolutionary algorithm is used with a commercial CFD code ANSYS-CFX. The optimization is aiming at improving the static pressure coefficient at design point and at low flow rate condition while constraining the slope of the lift coefficient curve. Moreover, a small tip clearance of the LSD blade was applied in order to activate and to stabilize the secondary flow effect at small flow rate condition. The optimized LSD blade has an extended operating range of 114 % towards smaller flow rate as compared to the baseline design without deteriorating the diffuser pressure recovery at design point. The diffuser pressure rise and operating flow range of the optimized LSD blade are experimentally verified by overall performance test. The detailed flow in the diffuser is also confirmed by means of a Particle Image Velocimeter. Secondary flow is clearly captured by PIV and it spreads to the whole area of LSD blade pitch. It is found that the optimized LSD blade shows good improvement of the blade loading in the whole operating range, while at small flow rate the flow separation on the LSD blade has been successfully suppressed by the secondary flow effect.

Characterizing pressure issues due to turbulent flow in tubing, in ultra-fast chiral supercritical fluid chromatography at up to 580bar.

PubMed

Berger, Terry A

2016-12-02

It has been widely suggested that the outlet pressure be changed to maintain constant density ("isopycnic" conditions) when comparing the kinetic performance of different columns in supercritical fluid chromatography (SFC). However, at high flow rates, flow in the tubing is turbulent, causing large extra-column pressure drops that limit options for changing outlet pressure. Some of these pressure drops occur before and some after the column, obscuring the actual column inlet and outlet pressures. In this work, a 4.6×100mm, 1.8μm R,R-Whelk-O1 column was used with low dispersion LD (120μm) plumbing to generate sub-1min chiral separations. However, the optimum, or near optimum, flow rate was 5mL-min -1 , producing a system pressure of 580bar (with 40% methanol, outlet pressure 120bar). Both the flow rate and pump pressure required were near the limits of the instrument, and significantly exceeded the capability of many other SFC's. Extra-column pressure drops (ΔP ec ) were as high as 200bar, caused mostly by turbulent flow in the tubing. The ΔP ec increased by more than the square of the flow rate. Reynolds Numbers (Re) were calculated for tubing as a function of flow rate between 100 and 400bar and 5-20% methanol in CO 2 , and 40°-60°C. This represents the most extensive analysis of turbulence in tubing in the SFC literature. Flow in 120μm ID tubing was calculated to be laminar below 1.0mL-min -1 , mostly transitional up to 2.5mL-min -1 and virtually always turbulent at 3mL-min -1 and higher. Flow in 170μm tubing is turbulent at lower flows but generates half the ΔP ec due to the lower mobile phase linear velocity. The results suggest that, while sub-minute chromatograms are easily generated, 4.6mm columns are not very user friendly for use with sub-2μm packings. The high flow rates required just to reach optimum result in high ΔP ec generated by the tubing, causing uncertainty in the true column inlet, outlet, and average column pressure/density. When comparing kinetic performance of columns with different dimensions, the pressure drops in the tubing must be considered. Copyright © 2016 Elsevier B.V. All rights reserved.

How can we maximize the diagnostic utility of uroflow?: ICI-RS 2017.

PubMed

Gammie, Andrew; Rosier, Peter; Li, Rui; Harding, Chris

2018-01-09

To gauge the current level of diagnostic utility of uroflowmetry and to suggest areas needing research to improve this. A summary of the debate held at the 2017 meeting of the International Consultation on Incontinence Research Society, with subsequent analysis by the authors. Limited diagnostic sensitivity and specificity exist for maximum flow rates, multiple uroflow measurements, and flow-volume nomograms. There is a lack of clarity in flow rate curve shape description and uroflow time measurement. There is a need for research to combine uroflowmetry with other non-invasive indicators. Better standardizations of test technique, flow-volume nomograms, uroflow shape descriptions, and time measurements are required. © 2017 Wiley Periodicals, Inc.

Storage requirements for Arkansas streams

USGS Publications Warehouse

Patterson, James Lee

1968-01-01

The supply of good-quality surface water in Arkansas is abundant. owing to seasonal and annual variability of streamflow, however, storage must be provided to insure dependable year-round supplies in most of the State. Storage requirements for draft rates that are as much as 60 percent of the mean annual flow at 49 continuous-record gaging stations can be obtained from tabular data in this report. Through regional analyses of streamflow data, the State was divided into three regions. Draft-storage diagrams for each region provide a means of estimating storage requirements for sites on streams where data are scant, provided the drainage area, the mean annual flow, and the low-flow index are known. These data are tabulated for 53 gaging stations used in the analyses and for 132 partial-record sites where only base-flow measurements have been made. Mean annual flow can be determined for any stream whose drainage lies within the State by using the runoff map in this report. Low-flow indices can be estimated by correlating base flows, determined from several discharge measurements, with concurrent flows at nearby continuous-record gaging stations, whose low-flow indices have been determined.

76 FR 48159 - Integrated System Power Rates

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-08

... rates, as are those of Southwestern's transmission facilities, which consist of 1,380 miles of high... system investments within the required number of years. As indicated in the Integrated System Rate Design... decrease slightly to reflect the incorporation of the White River Minimum Flows legislation as applied to...

SHINE Vacuum Pump Test Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, Gregg A; Peters, Brent

2013-09-30

Normetex pumps used world-wide for tritium service are no longer available. DOE and other researchers worldwide have spent significant funds characterizing this pump. Identification of alternate pumps is required for performance and compatibility with tritium gas. Many of the pumps that could be used to meet the functional performance requirements (e.g. pressure and flow conditions) of the Normetex pump have features that include the use of polymers or oils and greases that are not directly compatible with tritium service. This study assembles a test system to determine the flow characteristics for candidate alternate pumps. These tests are critical to themore » movement of tritium through the SHINE Tritium Purification System (TPS). The purpose of the pump testing is two-fold: (1) obtain baseline vacuum pump characteristics for an alternate (i.e. ''Normetex replacement'') pump intended for use in tritium service; and (2) verify that low pressure hydrogen gas can be transported over distances up to 300 feet by the candidate pumps. Flow rates and nominal system pressures have been identified for the SHINE Mo-99 production process Tritium Purification System (TPS). To minimize the line sizes for the transfer of low pressure tritium from the Neutron Driver Accelerator System (NDAS) to the primary processing systems in the TPS, a ''booster'' pump has been located near the accelerator in the design. A series of pump tests were performed at various configurations using hydrogen gas (no tritium) to ensure that this concept is practical and maintains adequate flow rates and required pressures. This report summarizes the results of the tests that have been performed using various pump configurations. The current design of the Tritium Purification System requires the ''booster'' pump to discharge to or to be backed by another vacuum pump. Since Normetex pumps are no longer manufactured, a commercially available Edwards scroll pump will be used to back the booster pump. In this case the ''booster pump'' is an Adixen Molecular Drag Pump (MDP 5011) and the backing pump is an Edwards (nXDS15iC) scroll pump. Various configurations of the two pumps and associated lengths of 3/4 inch tubing (0 feet to 300 feet) were used in combination with hydrogen and nitrogen flow rates ranging from 25-400 standard cubic centimeters per minute (sccm) to determine whether the proposed pump configuration meets the design criteria for SHINE. The results of this study indicate that even under the most severe conditions (300 feet of tubing and 400 sccm flow rate) the Adixen 5011 MDP can serve as a booster pump to transport gases from the accelerator (NDAS) to the TPS. The Target Gas Receiving System pump (Edwards nXDS15iC) located approximately 300 feet from the accelerator can effectively back the Adixen MDP. The molecular drag pump was able to maintain its full rotational speed even when the flow rate was 400 sccm hydrogen or nitrogen and 300 feet of tubing was installed between the drag pump and the Edwards scroll pump. In addition to maintaining adequate rotation, the pressure in the system was maintained below the target pressure of 30 torr for all flow rates, lengths of tubing, and process gases. This configuration is therefore adequate to meet the SHINE design requirements in terms of flow and pressure.« less

Inertial Particle Migration in the Presence of a Permeate Flow

NASA Astrophysics Data System (ADS)

Garcia, Mike; Singelton, Amanda; Pennathur, Sumita

2016-11-01

Tangential Flow Filtration (TFF) is a rapid and efficient method for the filtration and separation of suspensions of particles such as viruses, bacteria or cellular material. Enhancing the efficacy of TFF not only requires a detailed understanding of particle transport mechanisms, but also the interactions between these mechanisms and a porous wall. In this work, we numerically and experimentally explore the mechanisms of inertial particle migration in the presence of a permeate flow through the porous walls of a microchannel. Numerically, we develop a force balance model to understand the competition between permeate and inertial forces and the resultant consequences on the particle equilibrium location. Experimentally, we fabricated MEMS TFF devices to study the migration of 5, 10 and 15 µm fluorescent polystyrene beads in straight channels with perpendicular permeate flow rates up to 90% of the inlet flow rate. We find that the permeate flow directly influences the inertial focusing position of the particles, both as a function of downstream channel position and ratio of inlet to outlet flow rate. Comparing experiments to our model, we can identify inertial, viscous and a co-dominant regimes.

Aquatic Pest Control. Bulletin 754.

ERIC Educational Resources Information Center

Miller, James F.

Four groups of aquatic weeds are described: algae, floating weeds, emersed weeds, and submersed weeds. Specific requirements for pesticide application are given for static water, limited flow, and moving water situations. The secondary effects of improper pesticide application rates are given for static, limited flow, and moving water, and the…

Radial blanket assembly orificing arrangement

DOEpatents

Patterson, J.F.

1975-07-01

A nuclear reactor core for a liquid metal cooled fast breeder reactor is described in which means are provided for increasing the coolant flow through the reactor fuel assemblies as the reactor ages by varying the coolant flow rate with the changing coolant requirements during the core operating lifetime. (auth)

Estimation of inhalation flow profile using audio-based methods to assess inhaler medication adherence.

PubMed

Taylor, Terence E; Lacalle Muls, Helena; Costello, Richard W; Reilly, Richard B

2018-01-01

Asthma and chronic obstructive pulmonary disease (COPD) patients are required to inhale forcefully and deeply to receive medication when using a dry powder inhaler (DPI). There is a clinical need to objectively monitor the inhalation flow profile of DPIs in order to remotely monitor patient inhalation technique. Audio-based methods have been previously employed to accurately estimate flow parameters such as the peak inspiratory flow rate of inhalations, however, these methods required multiple calibration inhalation audio recordings. In this study, an audio-based method is presented that accurately estimates inhalation flow profile using only one calibration inhalation audio recording. Twenty healthy participants were asked to perform 15 inhalations through a placebo Ellipta™ DPI at a range of inspiratory flow rates. Inhalation flow signals were recorded using a pneumotachograph spirometer while inhalation audio signals were recorded simultaneously using the Inhaler Compliance Assessment device attached to the inhaler. The acoustic (amplitude) envelope was estimated from each inhalation audio signal. Using only one recording, linear and power law regression models were employed to determine which model best described the relationship between the inhalation acoustic envelope and flow signal. Each model was then employed to estimate the flow signals of the remaining 14 inhalation audio recordings. This process repeated until each of the 15 recordings were employed to calibrate single models while testing on the remaining 14 recordings. It was observed that power law models generated the highest average flow estimation accuracy across all participants (90.89±0.9% for power law models and 76.63±2.38% for linear models). The method also generated sufficient accuracy in estimating inhalation parameters such as peak inspiratory flow rate and inspiratory capacity within the presence of noise. Estimating inhaler inhalation flow profiles using audio based methods may be clinically beneficial for inhaler technique training and the remote monitoring of patient adherence.

Estimation of inhalation flow profile using audio-based methods to assess inhaler medication adherence

PubMed Central

Lacalle Muls, Helena; Costello, Richard W.; Reilly, Richard B.

2018-01-01

Asthma and chronic obstructive pulmonary disease (COPD) patients are required to inhale forcefully and deeply to receive medication when using a dry powder inhaler (DPI). There is a clinical need to objectively monitor the inhalation flow profile of DPIs in order to remotely monitor patient inhalation technique. Audio-based methods have been previously employed to accurately estimate flow parameters such as the peak inspiratory flow rate of inhalations, however, these methods required multiple calibration inhalation audio recordings. In this study, an audio-based method is presented that accurately estimates inhalation flow profile using only one calibration inhalation audio recording. Twenty healthy participants were asked to perform 15 inhalations through a placebo Ellipta™ DPI at a range of inspiratory flow rates. Inhalation flow signals were recorded using a pneumotachograph spirometer while inhalation audio signals were recorded simultaneously using the Inhaler Compliance Assessment device attached to the inhaler. The acoustic (amplitude) envelope was estimated from each inhalation audio signal. Using only one recording, linear and power law regression models were employed to determine which model best described the relationship between the inhalation acoustic envelope and flow signal. Each model was then employed to estimate the flow signals of the remaining 14 inhalation audio recordings. This process repeated until each of the 15 recordings were employed to calibrate single models while testing on the remaining 14 recordings. It was observed that power law models generated the highest average flow estimation accuracy across all participants (90.89±0.9% for power law models and 76.63±2.38% for linear models). The method also generated sufficient accuracy in estimating inhalation parameters such as peak inspiratory flow rate and inspiratory capacity within the presence of noise. Estimating inhaler inhalation flow profiles using audio based methods may be clinically beneficial for inhaler technique training and the remote monitoring of patient adherence. PMID:29346430

Effects of alternative instream-flow criteria and water-supply demands on ground-water development options in the Big River Area, Rhode Island

USGS Publications Warehouse

Granato, Gregory E.; Barlow, Paul M.

2005-01-01

Transient numerical ground-water-flow simulation and optimization techniques were used to evaluate potential effects of instream-flow criteria and water-supply demands on ground-water development options and resultant streamflow depletions in the Big River Area, Rhode Island. The 35.7 square-mile (mi2) study area includes three river basins, the Big River Basin (30.9 mi2), the Carr River Basin (which drains to the Big River Basin and is 7.33 mi2 in area), the Mishnock River Basin (3.32 mi2), and a small area that drains directly to the Flat River Reservoir. The overall objective of the simulations was to determine the amount of ground water that could be withdrawn from the three basins when constrained by streamflow requirements at four locations in the study area and by maximum rates of withdrawal at 13 existing and hypothetical well sites. The instream-flow requirement for the outlet of each basin and the outfall of Lake Mishnock were the primary variables that limited the amount of ground water that could be withdrawn. A requirement to meet seasonal ground-water-demand patterns also limits the amount of ground water that could be withdrawn by up to about 50 percent of the total withdrawals without the demand-pattern constraint. Minimum water-supply demands from a public water supplier in the Mishnock River Basin, however, did not have a substantial effect on withdrawals in the Big River Basin. Hypothetical dry-period instream-flow requirements and the effects of artificial recharge also affected the amount of ground water that could be withdrawn. Results of simulations indicate that annual average ground-water withdrawal rates that range up to 16 million gallons per day (Mgal/d) can be withdrawn from the study area under simulated average hydrologic conditions depending on instream-flow criteria and water-supply demand patterns. Annual average withdrawals of 10 to 12 Mgal/d are possible for proposed demands of 3.4 Mgal/d in the Mishnock Basin, and for a constant annual instream-flow criterion of 0.5 cubic foot per second per square mile (ft3/s/mi2) at the four streamflow-constraint locations. An average withdrawal rate of 10 Mgal/d can meet estimates of future (2020) water-supply needs of surrounding communities in Rhode Island. This withdrawal rate represents about 13 percent of the average 2002 daily withdrawal from the Scituate Reservoir (76 Mgal/d), the State?s largest water supply. Average annual withdrawal rates of 6 to 7 Mgal/d are possible for more stringent instream-flow criteria that might be used during dry-period hydrologic conditions. Two example scenarios of dry-period instream-flow constraints were evaluated: first, a minimum instream flow of 0.1 cubic foot per second at any of the four constraint locations; and second, a minimum instream flow of 10 percent of the minimum monthly streamflow estimate for each streamflow-constraint location during the period 1961?2000. The State of Rhode Island is currently (2004) considering methods for establishing instream-flow criteria for streams within the State. Twelve alternative annual, seasonal, or monthly instream-flow criteria that have been or are being considered for application in southeastern New England were used as hypothetical constraints on maximum ground-water-withdrawal rates in management-model calculations. Maximum ground-water-withdrawal rates ranged from 5 to 16 Mgal/d under five alternative annual instream-flow criteria. Maximum ground-water-withdrawal rates ranged from 0 to 13.6 Mgal/d under seven alternative seasonal or monthly instream-flow criteria. The effect of ground-water withdrawals on seasonal variations in monthly average streamflows under each criterion also were compared. Evaluation of management-model results indicates that a single annual instream-flowcriterion may be sufficient to preserve seasonal variations in monthly average streamflows and meet water-supply demands in the Big River Area, because withdrawals from wells in the Big

Storage requirements for Georgia streams

USGS Publications Warehouse

Carter, Robert F.

1983-01-01

The suitability of a stream as a source of water supply or for waste disposal may be severely limited by low flow during certain periods. A water user may be forced to provide storage facilities to supplement the natural flow if the low flow is insufficient for his needs. This report provides data for evaluating the feasibility of augmenting low streamflow by means of storage facilities. It contains tabular data on storage requirements for draft rates that are as much as 60 percent of the mean annual flow at 99 continuous-record gaging stations, and draft-storage diagrams for estimating storage requirements at many additional sites. Through analyses of streamflow data, the State was divided into four regions. Draft-storage diagrams for each region provide a means of estimating storage requirements for sites on streams where data are scant, provided the drainage area, mean annual flow, and the 7-day, 10-year low flow are known or can be estimated. These data are tabulated for the 99 gaging stations used in the analyses and for 102 partial-record sites where only base-flow measurements have been made. The draft-storage diagrams are useful not only for estimating in-channel storage required for low-flow augmentation, but also can be used for estimating the volume of off-channel storage required to retain wastewater during low-flow periods for later release. In addition, these relationships can be helpful in estimating the volume of wastewater to be disposed of by spraying on land, provided that the water disposed of in this manner is only that for which streamflow dilution water is not currently available. Mean annual flow can be determined for any stream within the State by using the runoff map in this report. Low-flow indices can be estimated by several methods, including correlation of base-flow measurements with concurrent flow at nearby continuous-record gaging stations where low-flow indices have been determined.

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Laminar Flow Supersonic Wind Tunnel primary air injector

NASA Technical Reports Server (NTRS)

Smith, Brooke Edward

1993-01-01

This paper describes the requirements, design, and prototype testing of the flex-section and hinge seals for the Laminar Flow Supersonic Wind Tunnel Primary Injector. The supersonic atmospheric primary injector operates between Mach 1.8 and Mach 2.2 with mass-flow rates of 62 to 128 lbm/s providing the necessary pressure reduction to operate the tunnel in the desired Reynolds number (Re) range.

Flow past a rotating cylinder

NASA Astrophysics Data System (ADS)

Mittal, Sanjay; Kumar, Bhaskar

2003-02-01

Flow past a spinning circular cylinder placed in a uniform stream is investigated via two-dimensional computations. A stabilized finite element method is utilized to solve the incompressible Navier Stokes equations in the primitive variables formulation. The Reynolds number based on the cylinder diameter and free-stream speed of the flow is 200. The non-dimensional rotation rate, [alpha] (ratio of the surface speed and freestream speed), is varied between 0 and 5. The time integration of the flow equations is carried out for very large dimensionless time. Vortex shedding is observed for [alpha] < 1.91. For higher rotation rates the flow achieves a steady state except for 4.34 < [alpha] < 4:70 where the flow is unstable again. In the second region of instability, only one-sided vortex shedding takes place. To ascertain the instability of flow as a function of [alpha] a stabilized finite element formulation is proposed to carry out a global, non-parallel stability analysis of the two-dimensional steady-state flow for small disturbances. The formulation and its implementation are validated by predicting the Hopf bifurcation for flow past a non-rotating cylinder. The results from the stability analysis for the rotating cylinder are in very good agreement with those from direct numerical simulations. For large rotation rates, very large lift coefficients can be obtained via the Magnus effect. However, the power requirement for rotating the cylinder increases rapidly with rotation rate.

Low flow vortex shedding flowmeter for hypergolics/all media

NASA Technical Reports Server (NTRS)

Thinh, Ngo

1990-01-01

A family of vortex shedding flowmeters for flow measurement of hypergols that requires a long term operation without removal from system lines was further developed. A family of vortex shedding flowmeters without moving parts was designed. The test loop to evaluate the meters for the Freon flow, which simulates the hypergolic fluids, was modified and reconstructed. Preliminary results were obtained on the output frequency characteristics of an 1/2 inch flowmeter as a function of the flow rate.

Transition regime analytical solution to gas mass flow rate in a rectangular micro channel

NASA Astrophysics Data System (ADS)

Dadzie, S. Kokou; Dongari, Nishanth

2012-11-01

We present an analytical model predicting the experimentally observed gas mass flow rate in rectangular micro channels over slip and transition regimes without the use of any fitting parameter. Previously, Sone reported a class of pure continuum regime flows that requires terms of Burnett order in constitutive equations of shear stress to be predicted appropriately. The corrective terms to the conventional Navier-Stokes equation were named the ghost effect. We demonstrate in this paper similarity between Sone ghost effect model and newly so-called 'volume diffusion hydrodynamic model'. A generic analytical solution to gas mass flow rate in a rectangular micro channel is then obtained. It is shown that the volume diffusion hydrodynamics allows to accurately predict the gas mass flow rate up to Knudsen number of 5. This can be achieved without necessitating the use of adjustable parameters in boundary conditions or parametric scaling laws for constitutive relations. The present model predicts the non-linear variation of pressure profile along the axial direction and also captures the change in curvature with increase in rarefaction.

Canali-type channels on Venus - Some genetic constraints

NASA Technical Reports Server (NTRS)

Komatsu, Goro; Kargel, Jeffrey S.; Baker, Victor R.

1992-01-01

Canali-type channels on Venus are unique because of their great lengths (up to 6800 km) and nearly constant channel cross sectional shapes along their paths. A simple model incorporating channel flow and radiative cooling suggests that common terrestrial-type tholeiite lava cannot sustain a superheated and turbulent state for the long distances required for thermal erosion of canali within allowable discharge rates. If canali formed mainly by constructional processes, laminar tholeiitic flow of relatively high, sustained discharge rates might travel the observed distances, but the absence of levees would need to be explained. An exotic low temperature, low viscosity lava like carbonatite or sulfur seems to be required for the erosional genesis of canali.

40 CFR Table 12 to Subpart G of... - Monitoring Requirements for Treatment Processes

Code of Federal Regulations, 2013 CFR

2013-07-01

... Appropriate methods as specified in § 63.143 and as approved by permitting authority. 2. Steam stripper (i... recorder. (ii) Wastewater feed mass flow rate; and Continuously Liquid flow meter installed at stripper... operating temperature Continuously (A) Liquid temperature monitoring device installed at stripper influent...

40 CFR Table 12 to Subpart G of... - Monitoring Requirements for Treatment Processes

Code of Federal Regulations, 2010 CFR

2010-07-01

... Appropriate methods as specified in § 63.143 and as approved by permitting authority. 2. Steam stripper (i... recorder. (ii) Wastewater feed mass flow rate; and Continuously Liquid flow meter installed at stripper... operating temperature Continuously (A) Liquid temperature monitoring device installed at stripper influent...

40 CFR Table 12 to Subpart G of... - Monitoring Requirements for Treatment Processes

Code of Federal Regulations, 2011 CFR

2011-07-01

... Appropriate methods as specified in § 63.143 and as approved by permitting authority. 2. Steam stripper (i... recorder. (ii) Wastewater feed mass flow rate; and Continuously Liquid flow meter installed at stripper... operating temperature Continuously (A) Liquid temperature monitoring device installed at stripper influent...

40 CFR Table 12 to Subpart G of... - Monitoring Requirements for Treatment Processes

Code of Federal Regulations, 2014 CFR

2014-07-01

... Appropriate methods as specified in § 63.143 and as approved by permitting authority. 2. Steam stripper (i... recorder. (ii) Wastewater feed mass flow rate; and Continuously Liquid flow meter installed at stripper... operating temperature Continuously (A) Liquid temperature monitoring device installed at stripper influent...

40 CFR Table 12 to Subpart G of... - Monitoring Requirements for Treatment Processes

Code of Federal Regulations, 2012 CFR

2012-07-01

... Appropriate methods as specified in § 63.143 and as approved by permitting authority. 2. Steam stripper (i... recorder. (ii) Wastewater feed mass flow rate; and Continuously Liquid flow meter installed at stripper... operating temperature Continuously (A) Liquid temperature monitoring device installed at stripper influent...

Method of Testing Oxygen Regulators

NASA Technical Reports Server (NTRS)

Sontag, Harcourt; Borlik, E L

1935-01-01

Oxygen regulators are used in aircraft to regulate automatically the flow of oxygen to the pilot from a cylinder at pressures ranging up to 150 atmospheres. The instruments are adjusted to open at an altitude of about 15,000 ft. and thereafter to deliver oxygen at a rate which increases with the altitude. The instruments are tested to determine the rate of flow of oxygen delivered at various altitudes and to detect any mechanical defects which may exist. A method of testing oxygen regulators was desired in which the rate of flow could be determined more accurately than by the test method previously used (reference 1) and by which instruments defective mechanically could be detected. The new method of test fulfills these requirements.

Selective Catalytic Combustion Sensors for Reactive Organic Analysis

NASA Technical Reports Server (NTRS)

Innes, W. B.

1971-01-01

Sensors involving a vanadia-alumina catalyst bed-thermocouple assembly satisfy requirements for simple, reproducible and rapid continuous analysis or reactive organics. Responses generally increase with temperature to 400 C and increase to a maximum with flow rate/catalyst volume. Selectivity decreases with temperature. Response time decreases with flow rate and increases with catalyst volume. At chosen optimum conditions calculated response which is additive and linear agrees better with photochemical reactivity than other methods for various automotive sources, and response to vehicle exhaust is insensitive to flow rate. Application to measurement of total reactive organics in vehicle exhaust as well as for gas chromatography detection illustrate utility. The approach appears generally applicable to high thermal effect reactions involving first order kinetics.

A randomised control study comparing the Infant Flow Driver with nasal continuous positive airway pressure in preterm infants.

PubMed

Mazzella, M; Bellini, C; Calevo, M G; Campone, F; Massocco, D; Mezzano, P; Zullino, E; Scopesi, F; Arioni, C; Bonacci, W; Serra, G

2001-09-01

To compare the effectiveness of the Infant Flow Driver (IFD) with single prong nasal continuous positive airway pressure (nCPAP) in preterm neonates affected by respiratory distress syndrome. Randomised controlled study. Between September 1997 and March 1999, 36 preterm infants who were eligible for CPAP treatment were randomly selected for either nCPAP or IFD and studied prospectively for changes in oxygen requirement and/or respiratory rate. The requirement for mechanical ventilation, complications of treatment, and effects on mid-term outcome were also evaluated. Use of the IFD had a significantly beneficial effect on both oxygen requirement and respiratory rate (p < 0.0001) when compared with nCPAP. Moreover, O(2) requirement and respiratory rate were significantly decreased by four hours (p < 0.001 and p < 0.03 respectively). The probability of remaining supplementary oxygen free over the first 48 hours of treatment was significantly higher in patients treated with the IFD than with nCPAP (p < 0.02). IFD treated patients had a higher success (weaning) rate (94% v 72 %) and shorter duration of treatment (49.3 (31) v 56 (29.7) hours respectively; mean (SD)), although the difference was not significant. IFD appears to be a feasible device for managing respiratory distress syndrome in preterm infants, and benefits may be had with regard to oxygen requirement and respiratory rate when compared with nCPAP. The trend towards reduced requirement for mechanical ventilation, shorter clinical recovery time, and shorter duration of treatment requires further evaluation in a multicentre randomised clinical trial.

Principle design and actuation of a dual chamber electromagnetic micropump with coaxial cantilever valves.

PubMed

Zordan, Enrico; Amirouche, Farid; Zhou, Yu

2010-02-01

This paper deals with the design and characterization of an electromagnetic actuation micropump with superimposed dual chambers. An integral part of microfluidic system includes micropumps which have become a critical design focus and have the potential to alter treatment and drug delivery requirements to patients. In this paper, conceptual design of variable geometrical nozzle/diffuser elements, coaxial cantilever valve, is proposed. It takes advantages of cantilever fluctuating valves with preset geometry to optimize and control fluid flow. The integration of this conceptual valve into a dual chamber micropump has increased the flow rate when compared to a single chamber micropump. This technique also allows for the fluid flow to be actively controlled by adjusting the movement of the intermediate membrane and the cantilever valves due to their fast response and large deflection properties when subjected to an electromagnetic field. To ensure reliability and performance of both the membrane and electromagnets, finite element method was used to perform the stress-strain analysis and optimize the membrane structure and electromagnet configuration. The frequency-dependent flow rates and backpressure are investigated for different frequencies by varying the applied currents from 1A to 1.75A. The current micropump design exhibits a backpressure of 58 mmH(2)O and has a water flow rate that reaches maximum at 1.985 ml/s under a 1.75A current with a resonance frequency of 45 Hz. This proposed micropump while at its initial prototype stage can satisfy the requirements of wide flow rate drug delivery applications. Its controllability and process design are attractive for high volume fabrication and low cost.

Effective Discharge and Annual Sediment Yield on Brazos River

NASA Astrophysics Data System (ADS)

Rouhnia, M.; Salehi, M.; Keyvani, A.; Ma, F.; Strom, K. B.; Raphelt, N.

2012-12-01

Geometry of an alluvial river alters dynamically over the time due to the sediment mobilization on the banks and bottom of the river channel in various flow rates. Many researchers tried to define a single representative discharge for these morphological processes such as "bank-full discharge", "effective discharge" and "channel forming discharge". Effective discharge is the flow rate in which, the most sediment load is being carried by water, in a long term period. This project is aimed to develop effective discharge estimates for six gaging stations along the Brazos River from Waco, TX to Rosharon, TX. The project was performed with cooperation of the In-stream Flow Team of the Texas Water Development Board (TWDB). Project objectives are listed as: 1) developing "Flow Duration Curves" for six stations based on mean-daily discharge by downloading the required, additional data from U.S Geological Survey website, 2) developing "Rating Curves" for six gaging stations after sampling and field measurements in three different flow conditions, 3) developing a smooth shaped "Sediment Yield Histogram" with a well distinguished peak as effective discharge. The effective discharge was calculated using two methods of manually and automatic bin selection. The automatic method is based on kernel density approximation. Cross-sectional geometry measurements, particle size distributions and water field samples were processed in the laboratory to obtain the suspended sediment concentration associated with flow rate. Rating curves showed acceptable trends, as the greater flow rate we experienced, the more sediment were carried by water.

Major salivary gland flow rates in young and old, generally healthy African Americans and whites.

PubMed Central

Jones, R. E.; Ship, J. A.

1995-01-01

Saliva is essential to maintain and preserve oral health. Previous studies of primarily white populations demonstrated that salivary gland flow rates are age-stable in healthy adults, but there are little data on African Americans of different ages. The purpose of this study was to determine if there is a relationship between age, gender, and race in unstimulated and stimulated parotid and submandibular salivary gland flow rates and to evaluate subjective responses to questions regarding salivary dysfunction. Sixty generally healthy, middle socioeconomic class African Americans and whites between the ages of 20 to 40 and 60 to 80 years were evaluated. The results indicate, in general, that objective and subjective measurements of major salivary gland flow rates are independent of age, gender, and race. Further studies are required using larger populations. These results suggest that signs and symptoms of dry mouth in the elderly regardless of race or gender should not be considered a normal sequela of aging. PMID:7897685

Water balance in irrigation districts. Uncertainty in on-demand pressurized networks

NASA Astrophysics Data System (ADS)

Sánchez-Calvo, Raúl; Rodríguez-Sinobas, Leonor; Juana, Luis; Laguna, Francisco Vicente

2015-04-01

In on-demand pressurized irrigation distribution networks, applied water volume is usually controlled opening a valve during a calculated time interval, and assuming constant flow rate. In general, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of pressure conditions. A pressure regulating valve PRV is the commonly used pressure regulating device in a hydrant, which, also, executes the open and close function. A hydrant feeds several irrigation units, requiring a wide range in flow rate. In addition, some flow meters are also available, one as a component of the hydrant and the rest are placed downstream. Every land owner has one flow meter for each group of field plots downstream the hydrant. Ideal PRV performance would maintain a constant downstream pressure. However, the true performance depends on both upstream pressure and the discharged flow rate. Theoretical flow rates values have been introduced into a PRV behavioral model, validated in laboratory, coupled with an on-demand irrigation district waterworks, composed by a distribution network and a multi-pump station. Variations on flow rate are simulated by taking into account the consequences of variations on climate conditions and also decisions in irrigation operation, such us duration and frequency application. The model comprises continuity, dynamic and energy equations of the components of both the PRV and the water distribution network. In this work the estimation of water balance terms during the irrigation events in an irrigation campaign has been simulated. The effect of demand concentration peaks has been estimated.

Assessing the effusion rate of lava flows from their thermal radiated energy: theoretical study and lab-scale experiments

NASA Astrophysics Data System (ADS)

Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

2010-12-01

A quantitative monitoring of lava flow is required to manage a volcanic crisis, in order to assess where the flow will go, and when will it stop. As the spreading of lava flows is mainly controlled by its rheology and the eruptive mass flux, the key question is how to evaluate them during the eruption (rather than afterwards.) A relationship between the lava flow temperature and the eruption rate is likely to exist, based on the first-order argument that higher eruption rates should correspond to larger energy radiated by a lava flow. The semi-empirical formula developed by Harris and co-workers (e.g. Harris et al., 2007) is used to estimate lava flow rate from satellite observations. However, the complete theoretical bases of this technique, especially its domain of validity, remain to be firmly established. Here we propose a theoretical study of the cooling of a viscous axisymmetric gravity current fed at constant flux rate to investigate whether or not this approach can and/or should be refined and/or modify to better assess flow rates. Our study focuses on the influence of boundary conditions at the surface of the flow, where cooling can occur both by radiation and convection, and at the base of the flow. Dimensionless numbers are introduced to quantify the relative interplay between the model parameters, such as the lava flow rate and the efficiency of the various cooling processes (conduction, convection, radiation.) We obtain that the thermal evolution of the flow can be described as a two-stage evolution. After a transient phase of dynamic cooling, the flow reaches a steady state, characterized by a balance between surface and base cooling and heat advection in the flow, in which the surface temperature structure is constant. The duration of the transient phase and the radiated energy in the steady regime are shown to be a function of the dimensionless numbers. In the case of lava flows, we obtain that the steady state regime is reached after a few days. In this regime, a thermal image provides a consistent estimate of the flow rate if the external cooling conditions are reasonably well constrained.

Pahoehoe and aa in Hawaii: volumetric flow rate controls the lava structure

NASA Astrophysics Data System (ADS)

Rowland, Scott K.; Walker, George Pl

1990-11-01

The historical records of Kilauea and Mauna Loa volcanoes reveal that the rough-surfaced variety of basalt lava called aa forms when lava flows at a high volumetric rate (>5 10 m3/s), and the smooth-surfaced variety called pahoehoe forms at a low volumetric rate (<5 10 m3/s). This relationship is well illustrated by the 1983 1990 and 1969 1974 eruptions of Kilauea and the recent eruptions of Mauna Loa. It is also illustrated by the eruptions that produced the remarkable paired flows of Mauna Loa, in which aa formed during an initial short period of high discharge rate (associated with high fountaining) and was followed by the eruption of pahoehoe over a sustained period at a low discharge rate (with little or no fountaining). The finest examples of paired lava flows are those of 1859 and 1880 1881. We attribute aa formation to rapid and concentrated flow in open channels. There, rapid heat loss causes an increase in viscosity to a threshold value (that varies depending on the actual flow velocity) at which, when surface crust is torn by differential flow, the underlying lava is unable to move sufficiently fast to heal the tear. We attribute pahoehoe formation to the flowage of lava at a low volumetric rate, commonly in tubes that minimize heat loss. Flow units of pahoehoe are small (usually <1 m thick), move slowly, develop a chilled skin, and become virtually static before the viscosity has risen, to the threshold value. We infer that the high-discharge-rate eruptions that generate aa flows result from the rapid emptying of major or subsidiary magma chambers. Rapid near-surface vesiculation of gas-rich magma leads to eruptions with high discharge rates, high lava fountains, and fast-moving channelized flows. We also infer that long periods of sustained flow at a low discharge rate, which favor pahoehoe, result from the development of a free and unimpeded pathway from the deep plumbing system of the volcano and the separation of gases from the magma before eruption. Achievement of this condition requires one or more episodes of rapid magma excursion through the rift zone to establish a stable magma pathway.

SINGLE-INTERVAL GAS PERMEABILITY ESTIMATION

EPA Science Inventory

Single-interval, steady-steady-state gas permeability testing requires estimation of pressure at a screened interval which in turn requires measurement of friction factors as a function of mass flow rate. Friction factors can be obtained by injecting air through a length of pipe...

Effect of binder burnout on the sealing performance of glass ceramics for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Ertugrul, Tugrul Y.; Celik, Selahattin; Mat, Mahmut D.

2013-11-01

The glass ceramics composite sealants are among few materials suitable for the solid oxide fuel cells (SOFC) due to their high operating temperatures (600 °C-850 °C). The glass ceramics chemically bond to both the metallic interconnector and the ceramic electrolyte and provide a gas tight connection. A careful and several stages manufacturing procedure is required to obtain a gas tight sealing. In this study, effects of binder burnout process on the sealing performance are investigated employing commercially available glass ceramic powders. The glass ceramic laminates are produced by mixing glass ceramic powders with the organic binders and employing a tape casting method. The laminates are sandwiched between the metallic interconnectors of an SOFC cell. The burnout and subsequent sealing quality are analyzed by measuring leakage rate and final macrostructure of sealing region. The effects of heating rate, dead weight load, solid loading, carrier gas and their flow rates are investigated. It is found that sealing quality is affected from all investigated parameters. While a slower heating rate is required for a better burnout, the mass flow rate of sweep gas must be adequate for removal of the burned gas. The leakage rate is reduced to 0.1 ml min-1 with 2 °C min-1 + 1 °C min-1 heating rate, 86.25% solid loading, 200 N dead weight load and 500 ml min-1 sweep gas flow rate.

A stochastic two-scale model for pressure-driven flow between rough surfaces

PubMed Central

Larsson, Roland; Lundström, Staffan; Wall, Peter; Almqvist, Andreas

2016-01-01

Seal surface topography typically consists of global-scale geometric features as well as local-scale roughness details and homogenization-based approaches are, therefore, readily applied. These provide for resolving the global scale (large domain) with a relatively coarse mesh, while resolving the local scale (small domain) in high detail. As the total flow decreases, however, the flow pattern becomes tortuous and this requires a larger local-scale domain to obtain a converged solution. Therefore, a classical homogenization-based approach might not be feasible for simulation of very small flows. In order to study small flows, a model allowing feasibly-sized local domains, for really small flow rates, is developed. Realization was made possible by coupling the two scales with a stochastic element. Results from numerical experiments, show that the present model is in better agreement with the direct deterministic one than the conventional homogenization type of model, both quantitatively in terms of flow rate and qualitatively in reflecting the flow pattern. PMID:27436975

A Continuous Method for Gene Flow

PubMed Central

Palczewski, Michal; Beerli, Peter

2013-01-01

Most modern population genetics inference methods are based on the coalescence framework. Methods that allow estimating parameters of structured populations commonly insert migration events into the genealogies. For these methods the calculation of the coalescence probability density of a genealogy requires a product over all time periods between events. Data sets that contain populations with high rates of gene flow among them require an enormous number of calculations. A new method, transition probability-structured coalescence (TPSC), replaces the discrete migration events with probability statements. Because the speed of calculation is independent of the amount of gene flow, this method allows calculating the coalescence densities efficiently. The current implementation of TPSC uses an approximation simplifying the interaction among lineages. Simulations and coverage comparisons of TPSC vs. MIGRATE show that TPSC allows estimation of high migration rates more precisely, but because of the approximation the estimation of low migration rates is biased. The implementation of TPSC into programs that calculate quantities on phylogenetic tree structures is straightforward, so the TPSC approach will facilitate more general inferences in many computer programs. PMID:23666937

Electroosmotic Flow Rectification in Membranes with Asymmetrically Shaped Pores: Effects of Current and Pore Density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, Gregory W.; Lopez, Marcos M.; Ramiah Rajasekaran, Pradeep

2015-07-09

We have recently demonstrated a new electrokinetic phenomenon—electroosmotic flow rectification in membranes with asymmetrically shaped pores. Flow rectification means that at constant driving force the flow rate in one direction through the membrane is faster than the flow rate in the opposite direction. EOF rectification could be of practical use in microfluidic devices incorporating porous membranes, but additional research is required. We explore here the effects of two key experimental variables—current density used to drive flow through the membrane and membrane pore density—on EOF rectification. We have found that the extent of EOF rectification, as quantified by the rectification ratio,more » increases with increasing current density. In contrast, the rectification ratio decreases with increasing membrane pore density. We propose explanations for these results based on simple EOF and membrane-transport theories.« less

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

DOEpatents

Hamel, William R.

1984-01-01

This invention relates to a new method and new apparatus for determining fluid mass flowrate 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 flowrate 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 flowrate 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 flowrate 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.

Simple microfluidic stagnation point flow geometries

PubMed Central

Dockx, Greet; Verwijlen, Tom; Sempels, Wouter; Nagel, Mathias; Moldenaers, Paula; Hofkens, Johan; Vermant, Jan

2016-01-01

A geometrically simple flow cell is proposed to generate different types of stagnation flows, using a separation flow and small variations of the geometric parameters. Flows with high local deformation rates can be changed from purely rotational, over simple shear flow, to extensional flow in a region surrounding a stagnation point. Computational fluid dynamic calculations are used to analyse how variations of the geometrical parameters affect the flow field. These numerical calculations are compared to the experimentally obtained streamlines of different designs, which have been determined by high speed confocal microscopy. As the flow type is dictated predominantly by the geometrical parameters, such simple separating flow devices may alleviate the requirements for flow control, while offering good stability for a wide variety of flow types. PMID:27462382

LAV@HAZARD: a Web-GIS Framework for Real-Time Forecasting of Lava Flow Hazards

NASA Astrophysics Data System (ADS)

Del Negro, C.; Bilotta, G.; Cappello, A.; Ganci, G.; Herault, A.

2014-12-01

Crucial to lava flow hazard assessment is the development of tools for real-time prediction of flow paths, flow advance rates, and final flow lengths. Accurate prediction of flow paths and advance rates requires not only rapid assessment of eruption conditions (especially effusion rate) but also improved models of lava flow emplacement. Here we present the LAV@HAZARD web-GIS framework, which combines spaceborne remote sensing techniques and numerical simulations for real-time forecasting of lava flow hazards. By using satellite-derived discharge rates to drive a lava flow emplacement model, LAV@HAZARD allows timely definition of parameters and maps essential for hazard assessment, including the propagation time of lava flows and the maximum run-out distance. We take advantage of the flexibility of the HOTSAT thermal monitoring system to process satellite images coming from sensors with different spatial, temporal and spectral resolutions. HOTSAT was designed to ingest infrared satellite data acquired by the MODIS and SEVIRI sensors to output hot spot location, lava thermal flux and discharge rate. We use LAV@HAZARD to merge this output with the MAGFLOW physics-based model to simulate lava flow paths and to update, in a timely manner, flow simulations. Thus, any significant changes in lava discharge rate are included in the predictions. A significant benefit in terms of computational speed was obtained thanks to the parallel implementation of MAGFLOW on graphic processing units (GPUs). All this useful information has been gathered into the LAV@HAZARD platform which, due to the high degree of interactivity, allows generation of easily readable maps and a fast way to explore alternative scenarios. We will describe and demonstrate the operation of this framework using a variety of case studies pertaining to Mt Etna, Sicily. Although this study was conducted on Mt Etna, the approach used is designed to be applicable to other volcanic areas around the world.

A Particle Representation Model for the Deformation of Homogeneous Turbulence

NASA Technical Reports Server (NTRS)

Kassinos, S. C.; Reynolds, W. C.

1996-01-01

In simple flows, where the mean deformation rates are mild and the turbulence has time to come to equilibrium with the mean flow, the Reynolds stresses are determined by the applied strain rate. Hence in these flows, it is often adequate to use an eddy-viscosity representation. The modern family of kappa-epsilon models has been very useful in predicting near equilibrium turbulent flows, where the rms deformation rate S is small compared to the reciprocal time scale of the turbulence (epsilon/kappa). In modern engineering applications, turbulence models are quite often required to predict flows with very rapid deformations (large S kappa/epsilon). In these flows, the structure takes some time to respond and eddy viscosity models are inadequate. The response of turbulence to rapid deformations is given by rapid distortion theory (RDT). Under RDT the nonlinear effects due to turbulence-turbulence interactions are neglected in the governing equations, but even when linearized in this fashion, the governing equations are unclosed at the one-point level due to the non-locality of the pressure fluctuations.

HEAT TRANSFER METHOD

DOEpatents

Gambill, W.R.; Greene, N.D.

1960-08-30

A method is given for increasing burn-out heat fluxes under nucleate boiling conditions in heat exchanger tubes without incurring an increase in pumping power requirements. This increase is achieved by utilizing a spinning flow having a rotational velocity sufficient to produce a centrifugal acceleration of at least 10,000 g at the tube wall. At this acceleration the heat-transfer rate at burn out is nearly twice the rate which can be achieved in a similar tube utilizing axial flow at the same pumping power. At higher accelerations the improvement over axial flow is greater, and heat fluxes in excess of 50 x 10/sup 6/ Btu/hr/sq ft can be achieved.

Analysis of the velocity distribution in different types of ventilation system ducts

NASA Astrophysics Data System (ADS)

Peszyński, Kazimierz; Olszewski, Lukasz; Smyk, Emil; Perczyński, Daniel

2018-06-01

The paper presents the results obtained during the preliminary studies of circular and rectangular ducts before testing the properties elements (elbows, tees, etc.)of rectangular with rounded corners ducts. The fundamental problem of the studies was to determine the flow rate in the ventilation duct. Due to the size of the channel it was decided to determine the flow rate based on the integration of flow velocity over the considered cross-section. This method requires knowledge of the velocity distribution in the cross section. Approximation of the measured actual profile by the classic and modified Prandtl power-law velocity profile was analysed.

Proceedings of the International Cryocoolers Conference (4th) Held in Easton, Maryland on 25-26 September 1986

DTIC Science & Technology

1987-10-30

simple relationship for the required refrigerant mass flow rate, m, for a given cooling load, q1l m = where Ah is the enthalpy difference between the cool...compressor concepts were tested to determine their performance. No measurable difference in performance was found and the first, more compact, concept was...resulting change in orifice size adjusts the mass flow rate through the valve. By reducing excursions in the pressure difference across the J-T valve, the

Combinational concentration gradient confinement through stagnation flow.

PubMed

Alicia, Toh G G; Yang, Chun; Wang, Zhiping; Nguyen, Nam-Trung

2016-01-21

Concentration gradient generation in microfluidics is typically constrained by two conflicting mass transport requirements: short characteristic times (τ) for precise temporal control of concentration gradients but at the expense of high flow rates and hence, high flow shear stresses (σ). To decouple the limitations from these parameters, here we propose the use of stagnation flows to confine concentration gradients within large velocity gradients that surround the stagnation point. We developed a modified cross-slot (MCS) device capable of feeding binary and combinational concentration sources in stagnation flows. We show that across the velocity well, source-sink pairs can form permanent concentration gradients. As source-sink concentration pairs are continuously supplied to the MCS, a permanently stable concentration gradient can be generated. Tuning the flow rates directly controls the velocity gradients, and hence the stagnation point location, allowing the confined concentration gradient to be focused. In addition, the flow rate ratio within the MCS rapidly controls (τ ∼ 50 ms) the location of the stagnation point and the confined combinational concentration gradients at low flow shear (0.2 Pa < σ < 2.9 Pa). The MCS device described in this study establishes the method for using stagnation flows to rapidly generate and position low shear combinational concentration gradients for shear sensitive biological assays.

40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

Code of Federal Regulations, 2012 CFR

2012-07-01

... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

Code of Federal Regulations, 2014 CFR

2014-07-01

... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

Code of Federal Regulations, 2010 CFR

2010-07-01

... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

Code of Federal Regulations, 2011 CFR

2011-07-01

... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

Vacuum-bag-only processing of composites

NASA Astrophysics Data System (ADS)

Thomas, Shad

Ultrasonic imaging in the C-scan mode in conjunction with the amplitude of the reflected signal was used to measure flow rates of an epoxy resin film penetrating through the thickness of single layers of woven carbon fabric. Assemblies, comprised of a single layer of fabric and film, were vacuum-bagged and ultrasonically scanned in a water tank during impregnation at 50°C, 60°C, 70°C, and 80°C. Measured flow rates were plotted versus inverse viscosity to determine the permeability in the thin film, non-saturated system. The results demonstrated that ultrasonic imaging in the C-scan mode is an effective method of measuring z-direction resin flow through a single layer of fabric. The permeability values determined in this work were consistent with permeability values reported in the literature. Capillary flow was not observed at the temperatures and times required for pressurized flow to occur. The flow rate at 65°C was predicted from the linear plot of flow rate versus inverse viscosity. The effects of fabric architecture on through-thickness flow rates during impregnation of an epoxy resin film were measured by ultrasonic imaging. Multilayered laminates comprised of woven carbon fabrics and epoxy films (prepregs) were fabricated by vacuum-bagging. Ultrasonic imaging was performed in a heated water tank (65°C) during impregnation. Impregnation rates showed a strong dependence on fabric architecture, despite similar areal densities. Impregnation rates are directly affected by inter-tow spacing and tow nesting, which depend on fabric architecture, and are indirectly affected by areal densities. A new method of predicting resin infusion rates in prepreg and resin film infusion processes was proposed. The Stokes equation was used to derive an equation to predict the impregnation rate of laminates as a function of fabric architecture. Flow rate data previously measured by ultrasound was analyzed with the new equation and the Kozeny-Carman equation. A fiber interaction parameter was determined as a function of fabric architecture. The derived equation is straight-forward to use, unlike the Kozeny-Carman equation. The results demonstrated that the newly derived equation can be used to predict the resin infusion rate of multilayer laminates.

Bone tissue engineering: the role of interstitial fluid flow

NASA Technical Reports Server (NTRS)

Hillsley, M. V.; Frangos, J. A.

1994-01-01

It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

Microfluidic oscillators with widely tunable periods

PubMed Central

Kim, Sung-Jin; Yokokawa, Ryuji; Takayama, Shuichi

2013-01-01

We present experiments and theory of a constant flow-driven microfluidic oscillator with widely tunable oscillation periods. This oscillator converts two constant input-flows from a syringe pump into an alternating, periodic output-flow with oscillation periods that can be adjusted to between 0.3 s to 4.1 h by tuning an external membrane capacitor. This capacitor allows multiple adjustable periods at a given input flow-rate, thus providing great flexibility in device operation. Also, we show that a sufficiently large external capacitance, relative to the internal capacitance of the microfluidic valve itself, is a critical requirement for oscillation. These widely tunable microfluidic oscillators are envisioned to be broadly useful for the study of biological rhythms, as on-chip timing sources for microfluidic logic circuits, and other applications that require variation in timed flow switching. PMID:23429765

46 CFR 98.25-40 - Valves, fittings, and accessories.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., United States of America Standard 300-pound standard minimum, fitted with suitable soft gasket material... shut-off valves located as close to the tank as possible. (d) Excess flow valves where required by this section shall close automatically at the rated flow of vapor or liquid as specified by the manufacturer...

Inclusion of TCAF model in XSPEC to study accretion flow dynamics around black hole candidates

NASA Astrophysics Data System (ADS)

Debnath, Dipak; Chakrabarti, Sandip Kumar; Mondal, Santanu

Spectral and Temporal properties of black hole candidates can be well understood with the Chakrabarti-Titarchuk solution of two component advective flow (TCAF). This model requires two accretion rates, namely, the Keplerian disk accretion rate and the sub-Keplerian halo accretion rate, the latter being composed of a low angular momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disk rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time we are able to create a user friendly version by implementing additive Table model FITS file into GSFC/NASA's spectral analysis software package XSPEC. This enables any user to extract physical parameters of accretion flows, such as two accretion rates, shock location, shock strength etc. for any black hole candidate. Most importantly, unlike any other theoretical model, we show that TCAF is capable of predicting timing properties from spectral fits, since in TCAF, a shock is responsible for deciding spectral slopes as well as QPO frequencies.

Impact of High-flow Nasal Cannula Therapy in Quality Improvement and Clinical Outcomes in a Non-invasive Ventilation Device-free Pediatric Intensive Care Unit.

PubMed

Can, Fulva Kamit; Anil, Ayse Berna; Anil, Murat; Zengin, Neslihan; Bal, Alkan; Bicilioglu, Yuksel; Gokalp, Gamze; Durak, Fatih; Ince, Gulberat

2017-10-15

To analyze the change in quality indicators due to the use of high-flow nasal cannula therapy as a non-invasive ventilation method in children with respiratory distress/failure in a non-invasive ventilation device-free pediatric intensive care unit. Retrospective chart review of children with respiratory distress/failure admitted 1 year before (period before high-flow nasal cannula therapy) and 1 year after (period after high-flow nasal cannula therapy) the introduction of high-flow nasal cannula therapy. We compared quality indicators as rate of mechanical ventilation, total duration of mechanical ventilation, rate of re-intubation, pediatric intensive care unit length of stay, and mortality rate between these periods. Between November 2012 and November 2014, 272 patients: 141 before and 131 after high-flow nasal cannula therapy were reviewed (median age was 20.5 mo). Of the patients in the severe respiratory distress/failure subgroup, the rate of intubation was significantly lower in period after than in period before high-flow nasal cannula therapy group (58.1% vs. 76.1%; P <0.05). The median pediatric intensive care unit length of stay was significantly shorter in patients who did not require mechanical ventilation in the period after than in the period before high-flow nasal cannula therapy group (3d vs. 4d; P<0,05). Implementation of high-flow nasal cannula therapy in pediatric intensive care unit significantly improves the quality of therapy and its outcomes.

Measurement of pressure and flow rates during irrigation of a root canal ex vivo with three endodontic needles.

PubMed

Boutsioukis, C; Lambrianidis, T; Kastrinakis, E; Bekiaroglou, P

2007-07-01

To monitor ex vivo intra-canal irrigation with three endodontic needles (25, 27 and 30 gauge) and compare them in terms of irrigant flow rate, intra-barrel pressure, duration of irrigation and volume of irrigant delivered. A testing system was constructed to allow measurement of selected variables with pressure and displacement transducers during ex vivo intra-canal irrigation with a syringe and three different needles (groups A, B, C) into a prepared root canal. Ten specialist endodontists performed the irrigation procedure. Each operator performed ten procedures with each needle. Data recorded by the transducers were analysed using Friedman's test, Wilcoxon Signed Rank test, Mann-Whitney U-test and Kendall's T(b) test. The level of significance was set to 95%. Significant differences were detected among the three needles for most variables. Duration of delivery and flow rates significantly decreased as the needle diameter increased, whilst pressure increased up to 400-550 kPa. Gender of the operator had a significant impact on the results. Experience of the operators (years) were negatively correlated to volume of irrigant (all groups), to the duration of delivery (groups A, B) and to the average flow rate (group A). Finer diameter needles require increased effort to deliver the irrigant and result in higher intra-barrel pressure. The syringe and needles used tolerated the pressure developed. Irrigant flow rate should be considered as a factor directly influencing flow beyond the needle. Wide variations of flow rate were observed among operators. Syringe irrigation appears difficult to standardize and control.

A randomised control study comparing the Infant Flow Driver with nasal continuous positive airway pressure in preterm infants

PubMed Central

Mazzella, M; Bellini, C; Calevo, M; Campone, F; Massocco, D; Mezzano, P; Zullino, E; Scopesi, F; Arioni, C; Bonacci, W; Serra, G

2001-01-01

OBJECTIVE—To compare the effectiveness of the Infant Flow Driver (IFD) with single prong nasal continuous positive airway pressure (nCPAP) in preterm neonates affected by respiratory distress syndrome.
DESIGN—Randomised controlled study.
PATIENTS—Between September 1997 and March 1999, 36 preterm infants who were eligible for CPAP treatment were randomly selected for either nCPAP or IFD and studied prospectively for changes in oxygen requirement and/or respiratory rate. The requirement for mechanical ventilation, complications of treatment, and effects on mid-term outcome were also evaluated.
RESULTS—Use of the IFD had a significantly beneficial effect on both oxygen requirement and respiratory rate (p < 0.0001) when compared with nCPAP. Moreover, O2 requirement and respiratory rate were significantly decreased by four hours (p < 0.001 and p < 0.03 respectively). The probability of remaining supplementary oxygen free over the first 48 hours of treatment was significantly higher in patients treated with the IFD than with nCPAP (p < 0.02). IFD treated patients had a higher success (weaning) rate (94% v 72%) and shorter duration of treatment (49.3 (31) v 56 (29.7) hours respectively; mean (SD)), although the difference was not significant.
CONCLUSIONS—IFD appears to be a feasible device for managing respiratory distress syndrome in preterm infants, and benefits may be had with regard to oxygen requirement and respiratory rate when compared with nCPAP. The trend towards reduced requirement for mechanical ventilation, shorter clinical recovery time, and shorter duration of treatment requires further evaluation in a multicentre randomised clinical trial.

 PMID:11517199

Application of partial inversion pulse to ultrasonic time-domain correlation method to measure the flow rate in a pipe

NASA Astrophysics Data System (ADS)

Wada, Sanehiro; Furuichi, Noriyuki; Shimada, Takashi

2017-11-01

This paper proposes the application of a novel ultrasonic pulse, called a partial inversion pulse (PIP), to the measurement of the velocity profile and flow rate in a pipe using the ultrasound time-domain correlation (UTDC) method. In general, the measured flow rate depends on the velocity profile in the pipe; thus, on-site calibration is the only method of checking the accuracy of on-site flow rate measurements. Flow rate calculation using UTDC is based on the integration of the measured velocity profile. The advantages of this method compared with the ultrasonic pulse Doppler method include the possibility of the velocity range having no limitation and its applicability to flow fields without a sufficient amount of reflectors. However, it has been previously reported that the measurable velocity range for UTDC is limited by false detections. Considering the application of this method to on-site flow fields, the issue of velocity range is important. To reduce the effect of false detections, a PIP signal, which is an ultrasound signal that contains a partially inverted region, was developed in this study. The advantages of the PIP signal are that it requires little additional hardware cost and no additional software cost in comparison with conventional methods. The effects of inversion on the characteristics of the ultrasound transmission were estimated through numerical calculation. Then, experimental measurements were performed at a national standard calibration facility for water flow rate in Japan. The experimental results demonstrate that measurements made using a PIP signal are more accurate and yield a higher detection ratio than measurements using a normal pulse signal.

Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

2014-01-10

Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. Copyright © 2013 Elsevier B.V. All rights reserved.

In-situ diagnostic tools for hydrogen transfer leak characterization in PEM fuel cell stacks part II: Operational applications

NASA Astrophysics Data System (ADS)

Niroumand, Amir M.; Homayouni, Hooman; DeVaal, Jake; Golnaraghi, Farid; Kjeang, Erik

2016-08-01

This paper describes a diagnostic tool for in-situ characterization of the rate and distribution of hydrogen transfer leaks in Polymer Electrolyte Membrane (PEM) fuel cell stacks. The method is based on reducing the air flow rate from a high to low value at a fixed current, while maintaining an anode overpressure. At high air flow rates, the reduction in air flow results in lower oxygen concentration in the cathode and therefore reduction in cell voltages. Once the air flow rate in each cell reaches a low value at which the cell oxygen-starves, the voltage of the corresponding cell drops to zero. However, oxygen starvation results from two processes: 1) the electrochemical oxygen reduction reaction which produces current; and 2) the chemical reaction between oxygen and the crossed over hydrogen. In this work, a diagnostic technique has been developed that accounts for the effect of the electrochemical reaction on cell voltage to identify the hydrogen leak rate and number of leaky cells in a fuel cell stack. This technique is suitable for leak characterization during fuel cell operation, as it only requires stack air flow and voltage measurements, which are readily available in an operational fuel cell system.

Evaluation of environmental flow requirements using eco-hydrologic-hydraulic methods in perennial rivers.

PubMed

Abdi, Reza; Yasi, Mehdi

2015-01-01

The assessment of environmental flows in rivers is of vital importance for preserving riverine ecosystem processes. This paper addresses the evaluation of environmental flow requirements in three reaches along a typical perennial river (the Zab transboundary river, in north-west Iran), using different hydraulic, hydrological and ecological methods. The main objective of this study came from the construction of three dams and inter-basin transfer of water from the Zab River to the Urmia Lake. Eight hydrological methods (i.e. Tennant, Tessman, flow duration curve analysis, range of variability approach, Smakhtin, flow duration curve shifting, desktop reserve and 7Q2&10 (7-day low flow with a 2- and 10-year return period)); two hydraulic methods (slope value and maximum curvature); and two habitat simulation methods (hydraulic-ecologic, and Q Equation based on water quality indices) were used. Ecological needs of the riverine key species (mainly Barbus capito fish), river geometries, natural flow regime and the environmental status of river management were the main indices for determining the minimum flow requirements. The results indicate that the order of 35%, 17% and 18% of the mean annual flow are to be maintained for the upper, middle and downstream river reaches, respectively. The allocated monthly flow rates in the three Dams steering program are not sufficient to preserve the Zab River life.

TI-59 helps predict IPRs for gravel-packed gas wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capdevielle, W.C.

The inflow performance relationship (IPR) is an important tool for reservoir and production engineers. It helps optimize completion, tubing, gas lift, and storm choke design. It facilitates accurate rate predictions that can be used to evaluate field development decisions. The IPR is the first step of the systems analysis that translates reservoir rock and fluid parameters into predictable flow rates. Use of gravel packing for sand control complicates the calculation that predicts a well's IPR curve, particularly in gas wells where high velocities in the formation and through gravel-filled perforation tunnels can cause turbulent flow. The program presented in thismore » article calculates the pressure drop and the flowing bottomhole pressures at varying flow rates for gravel-packed gas wells. The program was written for a Texas Instruments TI-59 programmable calculator with a PC-100 printer. Program features include: Calculations for in-casing gravel packs, open-hole gravel packs, or ungravel packed wells. Program prompts for the required data variables. Easy change of data values to run new cases. Calculates pressures for an unlimited number of flow rates. Results show the total pressure drop and the relative magnitude of its components.« less

Experimental Investigation of Two-Phase Oil (D130)-Water Flow in 4″ Pipe for Different Inclination Angles

NASA Astrophysics Data System (ADS)

Shaahid, S. M.; Basha, Mehaboob; Al-Hems, Luai M.

2018-03-01

Oil and water are often produced and transported together in pipelines that have various degrees of inclination from the horizontal. The flow of two immiscible liquids oil and water in pipes has been a research topic since several decades. In oil and chemical industries, knowledge of the frictional pressure loss in oil-water flows in pipes is necessary to specify the size of the pump required to pump the emulsions. An experimental investigation has been carried out for measurement of pressure drop of oil (D130)-water two-phase flows in 4 inch diameter inclined stainless steel pipe at different flow conditions. Experiments were conducted for different inclination angles including; 0°, 15°, 30° (for water cuts “WC” 0 - 100%). The flow rates at the inlet were varied from 4000 to 8000 barrels-per-day (BPD). For a given flow rate the frictional pressure drop has been found to increase (for all angles) from WC = 0 - 60%, and thereafter friction pressure drop decreases, this could be due phase inversion. For a given WC 40%, the frictional pressure drop has been found to increase with angle and flow rate. It has been noticed that inclination angle has appreciable effect on frictional pressure drop.

Comparison between uroflowmetry and sonouroflowmetry in recording of urinary flow in healthy men.

PubMed

Krhut, Jan; Gärtner, Marcel; Sýkora, Radek; Hurtík, Petr; Burda, Michal; Luňáček, Libor; Zvarová, Katarína; Zvara, Peter

2015-08-01

To evaluate the accuracy of sonouroflowmetry in recording urinary flow parameters and voided volume. A total of 25 healthy male volunteers (age 18-63 years) were included in the study. All participants were asked to carry out uroflowmetry synchronous with recording of the sound generated by the urine stream hitting the water level in the urine collection receptacle, using a dedicated cell phone. From 188 recordings, 34 were excluded, because of voided volume <150 mL or technical problems during recording. Sonouroflowmetry recording was visualized in a form of a trace, representing sound intensity over time. Subsequently, the matching datasets of uroflowmetry and sonouroflowmetry were compared with respect to flow time, voided volume, maximum flow rate and average flow rate. Pearson's correlation coefficient was used to compare parameters recorded by uroflowmetry with those calculated based on sonouroflowmetry recordings. The flow pattern recorded by sonouroflowmetry showed a good correlation with the uroflowmetry trace. A strong correlation (Pearson's correlation coefficient 0.87) was documented between uroflowmetry-recorded flow time and duration of the sound signal recorded with sonouroflowmetry. A moderate correlation was observed in voided volume (Pearson's correlation coefficient 0.68) and average flow rate (Pearson's correlation coefficient 0.57). A weak correlation (Pearson's correlation coefficient 0.38) between maximum flow rate recorded using uroflowmetry and sonouroflowmetry-recorded peak sound intensity was documented. The present study shows that the basic concept utilizing sound analysis for estimation of urinary flow parameters and voided volume is valid. However, further development of this technology and standardization of recording algorithm are required. © 2015 The Japanese Urological Association.

High-flow nasal prong oxygen therapy or nasopharyngeal continuous positive airway pressure for children with moderate-to-severe respiratory distress?*.

PubMed

ten Brink, Fia; Duke, Trevor; Evans, Janine

2013-09-01

The aim of this study was to compare the use of high-flow nasal prong oxygen therapy to nasopharyngeal continuous positive airway pressure in a PICU at a tertiary hospital; to understand the safety and effectiveness of high-flow nasal prong therapy; in particular, what proportion of children require escalation of therapy, whether any bedside monitoring data predict stability or need for escalation, and complications of the therapies. This was a prospective observational study of the first 6 months after the introduction of high-flow nasal prong oxygen therapy at the Royal Children's Hospital in Melbourne. Data were collected on all children who were managed with either high-flow nasal prong oxygen therapy or nasopharyngeal continuous positive airway pressure. The mode of respiratory support was determined by the treating medical staff. Data were collected on each patient before the use of high-flow nasal prong or nasopharyngeal continuous positive airway pressure, at 2 hours after starting the therapy, and the children were monitored and data collected until discharge from the ICU. Therapy was considered to be escalated if children on high-flow nasal prong required a more invasive form or higher level of respiratory support, including nasopharyngeal continuous positive airway pressure or mask bilevel positive airway pressure or endotracheal intubation and mechanical ventilation. Therapy was considered to be escalated if children on nasopharyngeal continuous positive airway pressure required bilevel positive airway pressure or intubation and mechanical ventilation. As the first mode of respiratory support, 72 children received high-flow nasal prong therapy and 37 received nasopharyngeal continuous positive airway pressure. Forty-four patients (61%) who received high-flow nasal prong first were weaned to low-flow oxygen or to room air and 21 (29%) required escalation of respiratory support, compared with children on nasopharyngeal continuous positive airway pressure: 21 (57%) weaned successfully and 9 (24%) required escalation. Repeated treatment and crossover were common in this cohort. Throughout the study duration, escalation to a higher level of respiratory support was needed in 26 of 100 high-flow nasal prong treatment episodes (26%) and in 10 of 55 continuous positive airway pressure episodes (18%; p = 0.27). The need for escalation could be predicted by two of failure of normalization of heart rate and respiratory rate, and if the FIO2 did not fall to lower than 0.5, 2 hours after starting high-flow nasal prong therapy. Nasopharyngeal continuous positive airway pressure was required for significantly longer periods than high-flow nasal prong (median 48 and 18 hours, respectively; p ≤ 0.001). High-flow nasal prong therapy is a safe form of respiratory support for children with moderate-to-severe respiratory distress, across a large range of diagnoses, whose increased work of breathing or hypoxemia is not relieved by standard oxygen therapy. About one quarter of all children will require escalation to another form of respiratory support. This can be predicted by simple bedside observations.

Topographic Effects on Geologic Mass Movements

NASA Technical Reports Server (NTRS)

Baloga, Stephen M.; Frey, Herbert (Technical Monitor)

2000-01-01

This report describes research directed toward understanding the response of volcanic lahars and lava flows to changes in the topography along the path of the flow. We have used a variety of steady-state and time-dependent models of lahars and lava flows to calculate the changes in flow dynamics due to variable topography. These models are based on first-order partial differential equations for the local conservation of volume. A global volume conservation requirement is also imposed to determine the extent of the flow as a function of time and the advance rate. Simulated DEMs have been used in this report.

[Efficacy of preoxygenation using tidal volume breathing: a comparison of Mapleson A, Bain's and Circle system].

PubMed

Arora, Suman; Gupta, Priyanka; Arya, Virender Kumar; Bhatia, Nidhi

Efficacy of preoxygenation depends upon inspired oxygen concentration, its flow rate, breathing system configuration and patient characteristics. We hypothesized that in actual clinical scenario, where breathing circuit is not primed with 100% oxygen, patients may need more time to achieve EtO 2 ≥90%, and this duration may be different among various breathing systems. We thus studied the efficacy of preoxygenation using unprimed Mapleson A, Bain's and Circle system with tidal volume breathing at oxygen flow rates of 5L.min -1 and 10L.min -1 . Patients were randomly allocated into one of the six groups, wherein they were preoxygenated using either Mapleson A, Bain's or Circle system at O 2 flow rate of either 5L.min -1 or 10L.min -1 . The primary outcome measure of our study was the time taken to achieve EtO 2 ≥90% at 5 and 10L.min -1 flow rates. At oxygen flow rate of 5L.min -1 , time to reach EtO 2 ≥90% was significantly longer with Bain's system (3.7±0.67min) than Mapleson A and Circle system (2.9±0.6, 3.3±0.97min, respectively). However at oxygen flow rate of 10L.min -1 this time was significantly shorter and comparable among all the three breathing systems (2.33±0.38min with Mapleson, 2.59±0.50min with Bain's and 2.60±0.47min with Circle system). With spontaneous normal tidal volume breathing at oxygen flow rate of 5L.min -1 , Mapleson A can optimally preoxygenate patients within 3min while Bain's and Circle system require more time. However at O 2 flow rate of 10L.min -1 all the three breathing systems are capable of optimally preoxygenating the patients in less than 3min. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

78 FR 69084 - Information Collection Request Submitted to OMB for Review and Approval; Comment Request...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-18

... quality assurance requirements in 40 CFR part 58, appendix A, require: ``2.6 Gaseous and Flow Rate Audit... Quality Assurance Regulations. These data and information are collected by state, local, and tribal air... ``EPA'' in any form of advertising.'' These requirements give assurance to end users that all specialty...

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

PubMed

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

2012-12-11

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

Review of flow rate estimates of the Deepwater Horizon oil spill

USGS Publications Warehouse

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

2012-01-01

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

Review of flow rate estimates of the Deepwater Horizon oil spill

PubMed Central

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

2012-01-01

The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ∼50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ∼5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly. PMID:22187459

40 CFR 75.15 - Special provisions for measuring Hg mass emissions using the excepted sorbent trap monitoring...

Code of Federal Regulations, 2010 CFR

2010-07-01

... the excepted sorbent trap monitoring methodology. For an affected coal-fired unit under a State or...; (c) A certified flow monitoring system is required; (d) Correction for stack gas moisture content is... proportional to the stack gas volumetric flow rate. (f) At the beginning and end of each sample collection...

[Feasibility Study on Digital Signal Processor and Gear Pump of Uroflowmeter Calibration Device].

PubMed

Yuan, Qing; Ji, Jun; Gao, Jiashuo; Wang, Lixin; Xiao, Hong

2016-08-01

It will cause hidden trouble on clinical application if the uroflowmeter is out of control.This paper introduces a scheme of uroflowmeter calibration device based on digital signal processor(DSP)and gear pump and shows studies of its feasibility.According to the research plan,we analyzed its stability,repeatability and linearity by building a testing system and carried out experiments on it.The flow test system is composed of DSP,gear pump and other components.The test results showed that the system could produce a stable water flow with high precision of repeated measurement and different flow rate.The test system can calibrate the urine flow rate well within the range of 9~50mL/s which has clinical significance,and the flow error is less than 1%,which meets the technical requirements of the calibration apparatus.The research scheme of uroflowmeter calibration device on DSP and gear pump is feasible.

Time variability in Cenozoic reconstructions of mantle heat flow: plate tectonic cycles and implications for Earth's thermal evolution.

PubMed

Loyd, S J; Becker, T W; Conrad, C P; Lithgow-Bertelloni, C; Corsetti, F A

2007-09-04

The thermal evolution of Earth is governed by the rate of secular cooling and the amount of radiogenic heating. If mantle heat sources are known, surface heat flow at different times may be used to deduce the efficiency of convective cooling and ultimately the temporal character of plate tectonics. We estimate global heat flow from 65 Ma to the present using seafloor age reconstructions and a modified half-space cooling model, and we find that heat flow has decreased by approximately 0.15% every million years during the Cenozoic. By examining geometric trends in plate reconstructions since 120 Ma, we show that the reduction in heat flow is due to a decrease in the area of ridge-proximal oceanic crust. Even accounting for uncertainties in plate reconstructions, the rate of heat flow decrease is an order of magnitude faster than estimates based on smooth, parameterized cooling models. This implies that heat flow experiences short-term fluctuations associated with plate tectonic cyclicity. Continental separation does not appear to directly control convective wavelengths, but rather indirectly affects how oceanic plate systems adjust to accommodate global heat transport. Given that today's heat flow may be unusually low, secular cooling rates estimated from present-day values will tend to underestimate the average cooling rate. Thus, a mechanism that causes less efficient tectonic heat transport at higher temperatures may be required to prevent an unreasonably hot mantle in the recent past.

Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

PubMed Central

Loyd, S. J.; Becker, T. W.; Conrad, C. P.; Lithgow-Bertelloni, C.; Corsetti, F. A.

2007-01-01

The thermal evolution of Earth is governed by the rate of secular cooling and the amount of radiogenic heating. If mantle heat sources are known, surface heat flow at different times may be used to deduce the efficiency of convective cooling and ultimately the temporal character of plate tectonics. We estimate global heat flow from 65 Ma to the present using seafloor age reconstructions and a modified half-space cooling model, and we find that heat flow has decreased by ∼0.15% every million years during the Cenozoic. By examining geometric trends in plate reconstructions since 120 Ma, we show that the reduction in heat flow is due to a decrease in the area of ridge-proximal oceanic crust. Even accounting for uncertainties in plate reconstructions, the rate of heat flow decrease is an order of magnitude faster than estimates based on smooth, parameterized cooling models. This implies that heat flow experiences short-term fluctuations associated with plate tectonic cyclicity. Continental separation does not appear to directly control convective wavelengths, but rather indirectly affects how oceanic plate systems adjust to accommodate global heat transport. Given that today's heat flow may be unusually low, secular cooling rates estimated from present-day values will tend to underestimate the average cooling rate. Thus, a mechanism that causes less efficient tectonic heat transport at higher temperatures may be required to prevent an unreasonably hot mantle in the recent past. PMID:17720806

Equations of motion for the variable mass flow-variable exhaust velocity rocket

NASA Technical Reports Server (NTRS)

Tempelman, W. H.

1972-01-01

An equation of motion for a one dimensional rocket is derived as a function of the mass flow rate into the acceleration chamber and the velocity distribution along the chamber, thereby including the transient flow changes in the chamber. The derivation of the mass density requires the introduction of the special time coordinate. The equation of motion is derived from both classical force and momentum approaches and is shown to be consistent with the standard equation expressed in terms of flow parameters at the exit to the acceleration chamber.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, Robert F.; Dietrich, Daniel D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

Design of an Efficient Turbulent Micro-Mixer for Protein Folding Experiments

NASA Astrophysics Data System (ADS)

Inguva, Venkatesh; Perot, Blair

2015-11-01

Protein folding studies require the development of micro-mixers that require less sample, mix at faster rates, and still provide a high signal to noise ratio. Chaotic to marginally turbulent micro-mixers are promising candidates for this application. In this study, various turbulence and unsteadiness generation concepts are explored that avoid cavitation. The mixing enhancements include flow turning regions, flow splitters, and vortex shedding. The relative effectiveness of these different approaches for rapid micro-mixing is discussed. Simulations found that flow turning regions provided the best mixing profile. Experimental validation of the optimal design is verified through laser confocal microscopy experiments. This work is support by the National Science Foundation.

Optimum aerobic volume control based on continuous in-line oxygen uptake monitoring.

PubMed

Svardal, K; Lindtner, S; Winkler, S

2003-01-01

Dynamic adaptation of the aerated volume to changing load conditions is essential to maximise the nitrogen removal performance and to minimise energy consumption. A control strategy is presented which provides optimum aerobic volume control (OAV-control concept) based on continuous in-line oxygen uptake monitoring. For ammonium concentrations below 1 mg/l the oxygen uptake rate shows a strong and almost linear dependency on the ammonium concentration. Therefore, the oxygen uptake rate is an ideal indicator for the nitrification performance in activated sludge systems. The OAV-control concept provides dynamic variation of the minimum aerobic volume required for complete nitrification and therefore maximises the denitrification performance. In-line oxygen uptake monitoring is carried out by controlling the oxygen concentration in a continuous aerated zone of the aeration tank and measuring the total air flow to the aeration tank. The total air flow to the aeration tank is directly proportional to the current oxygen uptake rate and can therefore be used as an indicator for the required aerobic volume. The instrumentation requirements for installation of the OAV-control are relatively low, oxygen sensors in the aeration tank and an on-line air flow measurement are needed. This enables individual control of aeration tanks operated in parallel at low investment costs. The OAV-control concept is installed at the WWTP Linz-Asten (1 Mio PE) and shows very good results. Full scale results are presented.

Experimental Assessment of the Reciprocating Feed System

NASA Technical Reports Server (NTRS)

Eddleman, David E.; Blackmon, James B.; Morton, Christopher D.

2006-01-01

The primary goal of this project was to design, construct, and test a full scale, high pressure simulated propellant feed system test bed that could evaluate the ability of the Reciprocating Feed System (RFS) to provide essentially constant flow rates and pressures to a rocket engine. The two key issues addressed were the effects of the transition of the drain cycle from tank to tank and the benefits of other hardware such as accumulators to provide a constant pressure flow rate out of the RFS. The test bed provided 500 psi flow at rates of the order of those required for engines in the 20,000 lbf thrust class (e.g., 20 to 40 lb/sec). A control system was developed in conjunction with the test article and automated system operation was achieved. Pre-test planning and acceptance activities such as a documented procedure and hazard analysis were conducted and the operation of the test article was approved by, and conducted in coordination with, appropriate NASA Marshall Space Flight Center personnel under a Space Act Agreement. Tests demonstrated successful control of flow rates and pressures.

Propellant Feed Subsystem for a 26 kW flight arcjet propulsion system

NASA Astrophysics Data System (ADS)

Vaughan, C. E.; Morris, J. P.

1993-06-01

The USAF arcjet ATTD program demanded the development of a low-cost ammonia Propellant Feed Subsystem (PFS). A flow rate of 240 +/- 5 mg/sec during a total of ten 15-min ammonia outflows was required for the flight mission. The precision of the flow tolerance required a departure from the design of previous ammonia propellant feed systems. Since a propellant management device was not used, thermocapillary forces were explored as a means to limit outflow of liquid phase ammonia. A high energy density feedline heater with an internal wick was developed to guarantee that only gas phase propellant would reach the arcjet. A digital control algorithm was developed to implement bang-bang control of mass flow rate metered by a sonic venturi. Development tests of this system have been completed. The system is capable of continuous gas phase outflows regardless of orientation. Integrated tests with the arcjet and power conditioning unit have also been successfully completed.

Development of hypersonic engine seals: Flow effects of preload and engine pressures

NASA Technical Reports Server (NTRS)

Cai, Zhong; Mutharasan, Rajakkannu; Ko, Frank K.; Steinetz, Bruce M.

1993-01-01

A new type of engine seal is being developed to meet the needs of advanced hypersonic engines. A seal braided of emerging high temperature ceramic fibers comprised of a sheath-core construction was selected for study based on its low leakage rates. Flexible, low-leakage, high temperature seals are required to seal the movable engine panels of advanced ramjet-scramjet engines either preventing potentially dangerous leakage into backside engine cavities or limiting the purge coolant flow rates through the seals. To predict the leakage through these flexible, porous seal structures as a function of preload and engine pressures, new analytical flow models are required. An empirical leakage resistance/preload model is proposed to characterize the observed decrease in leakage with increasing preload. Empirically determined compression modulus and preload factor are used to correlate experimental leakage data for a wide range of seal architectures. Good agreement between measured and predicted values are observed over a range of engine pressures and seal preloads.

Study on casing treatment and stator matching on multistage fan

NASA Astrophysics Data System (ADS)

Wu, Chuangliang; Yuan, Wei; Deng, Zhe

2017-10-01

Casing treatments are required for expanding the stall margin of multi-stage high-load turbofans designed with high blade-tip Mach numbers and high leakage flow. In the case of a low mass flow, the casing treatment effectively reduces the blockages caused by the leakage flow and enlarges the stall margin. However, in the case of a high mass flow, the casing treatment affects the overall flow capacity of the fan, the thrust when operating at the high speeds usually required by design-point specifications. Herein, we study a two-stage high-load fan with three-dimensional numerical simulations. We use the simulation results to propose a scheme that enlarges the stall margin of multistage high-load fans without sacrificing the flow capacity when operating with a large mass flow. Furthermore, a circumferential groove casing treatment is used and adjustments are made to the upstream stator angle to match the casing treatment. The stall margin is thus increased to 16.3%, with no reduction in the maximum mass flow rate or the design thrust performance.

Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

NASA Astrophysics Data System (ADS)

Wong, Ronnie J.; Jivraj, Jamil; Vuong, Barry; Ramjist, Joel; Sun, Cuiru; Huang, Yize; Yang, Victor X. D.

2015-03-01

The use of gas assistance in laser machining hard materials is well established in manufacturing but not in the context of surgery. Laser cutting of osseous tissue in the context of neurosurgery can benefit from gas-assist but requires an understanding of flow and pressure effects to minimize neural tissue damage. In this study we acquire volumetric flow rates through a gas nozzle on the spinal cord, with dura and without dura.

Supercomputer implementation of finite element algorithms for high speed compressible flows

NASA Technical Reports Server (NTRS)

Thornton, E. A.; Ramakrishnan, R.

1986-01-01

Prediction of compressible flow phenomena using the finite element method is of recent origin and considerable interest. Two shock capturing finite element formulations for high speed compressible flows are described. A Taylor-Galerkin formulation uses a Taylor series expansion in time coupled with a Galerkin weighted residual statement. The Taylor-Galerkin algorithms use explicit artificial dissipation, and the performance of three dissipation models are compared. A Petrov-Galerkin algorithm has as its basis the concepts of streamline upwinding. Vectorization strategies are developed to implement the finite element formulations on the NASA Langley VPS-32. The vectorization scheme results in finite element programs that use vectors of length of the order of the number of nodes or elements. The use of the vectorization procedure speeds up processing rates by over two orders of magnitude. The Taylor-Galerkin and Petrov-Galerkin algorithms are evaluated for 2D inviscid flows on criteria such as solution accuracy, shock resolution, computational speed and storage requirements. The convergence rates for both algorithms are enhanced by local time-stepping schemes. Extension of the vectorization procedure for predicting 2D viscous and 3D inviscid flows are demonstrated. Conclusions are drawn regarding the applicability of the finite element procedures for realistic problems that require hundreds of thousands of nodes.

Development of Fundamental Technologies for Micro Bioreactors

NASA Astrophysics Data System (ADS)

Sato, Kiichi; Kitamori, Takehiko

This chapter reviews the development of fundamental technologies required for microchip-based bioreactors utilizing living mammalian cells and pressure driven flow. The most important factor in the bioreactor is the cell culture. For proper cell culturing, continuous medium supply from a microfluidic channel and appropriate modification of the channel surface to accommodate cell attachment is required. Moreover, the medium flow rate should be chosen carefully, because shear stress affects cell activity. The techniques presented here could be applied to the development of micro bioreactors such as microlivers, pigment production by plant cells, and artificial insemination.

Renormalization group theory outperforms other approaches in statistical comparison between upscaling techniques for porous media

NASA Astrophysics Data System (ADS)

Hanasoge, Shravan; Agarwal, Umang; Tandon, Kunj; Koelman, J. M. Vianney A.

2017-09-01

Determining the pressure differential required to achieve a desired flow rate in a porous medium requires solving Darcy's law, a Laplace-like equation, with a spatially varying tensor permeability. In various scenarios, the permeability coefficient is sampled at high spatial resolution, which makes solving Darcy's equation numerically prohibitively expensive. As a consequence, much effort has gone into creating upscaled or low-resolution effective models of the coefficient while ensuring that the estimated flow rate is well reproduced, bringing to the fore the classic tradeoff between computational cost and numerical accuracy. Here we perform a statistical study to characterize the relative success of upscaling methods on a large sample of permeability coefficients that are above the percolation threshold. We introduce a technique based on mode-elimination renormalization group theory (MG) to build coarse-scale permeability coefficients. Comparing the results with coefficients upscaled using other methods, we find that MG is consistently more accurate, particularly due to its ability to address the tensorial nature of the coefficients. MG places a low computational demand, in the manner in which we have implemented it, and accurate flow-rate estimates are obtained when using MG-upscaled permeabilities that approach or are beyond the percolation threshold.

Performance Characteristics of a DME Propellant Arcjet Thruster

NASA Astrophysics Data System (ADS)

Kakami, Akira; Beeppu, Shinji; Maiguma, Muneyuki; Tachibana, Takeshi

This paper describes the influence of cathode configuration on performance of an arcjet thruster using dimethyl ether (DME) propellant. DME, an ether compound, has suitable characteristics for a space propulsion system; DME is storable in a liquid state without being kept under a high pressure, and requires no sophisticated temperature management such as a cryogenic device. DME can be gasified and liquefied simply by adjusting temperature whereas hydrazine, a conventional propellant, requires an iridium-based particulate catalyst for its gasification. In this study, thrust of a 1-kW class DME arcjet thruster is measured at a discharge current of 13 A, DME mass flow rates ranging 15 to 60 mg/s under three cathode configurations: flat-tip rods of 2 and 4 mm in diam. and 4-mm-diam. rod having a cavity of 2 mm in diameter. Thrust measurements show that thrust is increased with propellant mass flow rate. Among the tested cathodes, the flat-tip rod of 4 mm in diam. with 55 mg/s DME flow rate yielded the highest performance: specific impulse of 330 s, thrust of 0.18 N, discharge power of 1400 W and specific power of 25 MJ/kg.

Irrigation of human prepared root canal – ex vivo based computational fluid dynamics analysis

PubMed Central

Šnjarić, Damir; Čarija, Zoran; Braut, Alen; Halaji, Adelaida; Kovačević, Maja; Kuiš, Davor

2012-01-01

Aim To analyze the influence of the needle type, insertion depth, and irrigant flow rate on irrigant flow pattern, flow velocity, and apical pressure by ex-vivo based endodontic irrigation computational fluid dynamics (CFD) analysis. Methods Human upper canine root canal was prepared using rotary files. Contrast fluid was introduced in the root canal and scanned by computed tomography (CT) providing a three-dimensional object that was exported to the computer-assisted design (CAD) software. Two probe points were established in the apical portion of the root canal model for flow velocity and pressure measurement. Three different CAD models of 27G irrigation needles (closed-end side-vented, notched open-end, and bevel open-end) were created and placed at 25, 50, 75, and 95% of the working length (WL). Flow rates of 0.05, 0.1, 0.2, 0.3, and 0.4 mL/s were simulated. A total of 60 irrigation simulations were performed by CFD fluid flow solver. Results Closed-end side-vented needle required insertion depth closer to WL, regarding efficient irrigant replacement, compared to open-end irrigation needle types, which besides increased velocity produced increased irrigant apical pressure. For all irrigation needle types and needle insertion depths, the increase of flow rate was followed by an increased irrigant apical pressure. Conclusions The human root canal shape obtained by CT is applicable in the CFD analysis of endodontic irrigation. All the analyzed values –irrigant flow pattern, velocity, and pressure – were influenced by irrigation needle type, as well as needle insertion depth and irrigant flow rate. PMID:23100209

Irrigation of human prepared root canal--ex vivo based computational fluid dynamics analysis.

PubMed

Snjaric, Damir; Carija, Zoran; Braut, Alen; Halaji, Adelaida; Kovacevic, Maja; Kuis, Davor

2012-10-01

To analyze the influence of the needle type, insertion depth, and irrigant flow rate on irrigant flow pattern, flow velocity, and apical pressure by ex-vivo based endodontic irrigation computational fluid dynamics (CFD) analysis. Human upper canine root canal was prepared using rotary files. Contrast fluid was introduced in the root canal and scanned by computed tomography (CT) providing a three-dimensional object that was exported to the computer-assisted design (CAD) software. Two probe points were established in the apical portion of the root canal model for flow velocity and pressure measurement. Three different CAD models of 27G irrigation needles (closed-end side-vented, notched open-end, and bevel open-end) were created and placed at 25, 50, 75, and 95% of the working length (WL). Flow rates of 0.05, 0.1, 0.2, 0.3, and 0.4 mL/s were simulated. A total of 60 irrigation simulations were performed by CFD fluid flow solver. Closed-end side-vented needle required insertion depth closer to WL, regarding efficient irrigant replacement, compared to open-end irrigation needle types, which besides increased velocity produced increased irrigant apical pressure. For all irrigation needle types and needle insertion depths, the increase of flow rate was followed by an increased irrigant apical pressure. The human root canal shape obtained by CT is applicable in the CFD analysis of endodontic irrigation. All the analyzed values -irrigant flow pattern, velocity, and pressure - were influenced by irrigation needle type, as well as needle insertion depth and irrigant flow rate.

Heat Transfer Enhancement in High Performance Heat Sink Channels by Autonomous, Aero-Elastic Reed Fluttering

NASA Astrophysics Data System (ADS)

Jha, Sourabh; Crittenden, Thomas; Glezer, Ari

2016-11-01

Heat transport within high aspect ratio, rectangular mm-scale channels that model segments of a high-performance, air-cooled heat sink is enhanced by the formation of unsteady small-scale vortical motions induced by autonomous, aeroelastic fluttering of cantilevered planar thin-film reeds. The flow mechanisms and scaling of the interactions between the reed and the channel flow are explored to overcome the limits of forced convection heat transport from air-side heat exchangers. High-resolution PIV measurements in a testbed model show that undulations of the reed's surface lead to formation and advection of vorticity concentrations, and to alternate shedding of spanwise CW and CCW vortices. These vortices scale with the reed motion amplitude, and ultimately result in motions of decreasing scales and enhanced dissipation that are reminiscent of a turbulent flow. The vorticity shedding lead to strong enhancement in heat transfer that increases with the Reynolds number of the base flow (e.g., the channel's thermal coefficient of performance is enhanced by 2.4-fold and 9-fold for base flow Re = 4,000 and 17,400, respectively, with corresponding decreases of 50 and 77% in the required channel flow rates). This is demonstrated in heat sinks for improving the thermal performance of low-Re thermoelectric power plant air-cooled condensers, where the global air-side pressure losses can be significantly reduced by lowering the required air volume flow rate at a given heat flux and surface temperature. AFOSR and NSF-EPRI.

Simulating nailfold capillaroscopy sequences to evaluate algorithms for blood flow estimation.

PubMed

Tresadern, P A; Berks, M; Murray, A K; Dinsdale, G; Taylor, C J; Herrick, A L

2013-01-01

The effects of systemic sclerosis (SSc)--a disease of the connective tissue causing blood flow problems that can require amputation of the fingers--can be observed indirectly by imaging the capillaries at the nailfold, though taking quantitative measures such as blood flow to diagnose the disease and monitor its progression is not easy. Optical flow algorithms may be applied, though without ground truth (i.e. known blood flow) it is hard to evaluate their accuracy. We propose an image model that generates realistic capillaroscopy videos with known flow, and use this model to quantify the effect of flow rate, cell density and contrast (among others) on estimated flow. This resource will help researchers to design systems that are robust under real-world conditions.

Performance Characterization of the Production Facility Prototype Helium Flow System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woloshun, Keith Albert; Dale, Gregory E.; Dalmas, Dale Allen

2015-12-16

The roots blower in use at ANL for in-beam experiments and also at LANL for flow tests was sized for 12 mm diameter disks and significantly less beam heating. Currently, the disks are 29 mm in diameter, with a 12 mm FWHM Gaussian beam spot at 42 MeV and 2.86 μA on each side of the target, 5.72 μA total. The target design itself is reported elsewhere. With the increased beam heating, the helium flow requirement increased so that a larger blower was need for a mass flow rate of 400 g/s at 2.76 MPa (400 psig). An Aerzen GMmore » 12.4 blower was selected, and is currently being installed at the LANL facility for target and component flow testing. This report describes this blower/motor/pressure vessel package and the status of the facility preparations. Blower performance (mass flow rate as a function of loop pressure drop) was measured at 4 blower speeds. Results are reported below.« less

40 CFR 63.1104 - Process vents from continuous unit operations: applicability assessment procedures and methods.

Code of Federal Regulations, 2010 CFR

2010-07-01

... accordance with the applicable weight-percent, TOC concentration, or organic HAP concentration requirement in... rate, regulated organic HAP concentration, total organic HAP or TOC concentration, heating value, and... volumetric flow rate, regulated organic HAP concentration, total organic HAP or TOC concentration, and any...

Advanced Hybrid Cooling Loop Technology for High Performance Thermal Management

DTIC Science & Technology

2006-06-01

and Chung, 2003; Estes and Mudawar , 1995]. Because of the pumping pressure and flow rate requirements, such pumped systems require large pumping and...United States, April 24-25, 2003. 8. Estes, K. and Mudawar , I., “Comparison of Two-Phase Electronic Cooling Using Free Jets and Sprays”, Journal of

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 92.105 - General equipment specifications.

Code of Federal Regulations, 2010 CFR

2010-07-01

... measurements. Instruments used to measure engine power output shall comply with the requirements of § 92.106... they produce a permanent visual data record of a quality equal to or better than those required by this... calculating the engine intake humidity; (ii) The temperature of the fuel, in volume measuring flow rate...

Spiromax, a New Dry Powder Inhaler: Dose Consistency under Simulated Real-World Conditions.

PubMed

Canonica, Giorgio Walter; Arp, Jan; Keegstra, Johan René; Chrystyn, Henry

2015-10-01

Spiromax(®) is a novel dry powder inhaler for patients with asthma or chronic obstructive pulmonary disease (COPD). The studies presented here provide further data on attributes (in vitro dosing consistency with budesonide-formoterol (DuoResp) Spiromax; flow rates through empty versions of the Spiromax and Turbuhaler inhaler) of importance to patients with asthma or COPD. Dose-delivery studies were performed using low-, middle-, and high-strength DuoResp Spiromax. Dose consistency was assessed over inhaler life. Total emitted doses (TEDs) were measured at various flow rates, after exposure to high and low temperature or humidity, at different inhaler orientations, and after dropping the inhaler. The criterion for evaluating dose uniformity was whether mean TEDs were within the product specification limits. In separate studies, flow rates were measured after training, using the patient information leaflets, and again after enhanced training as part of a randomized, open-label, cross-over study. Mean values for both budesonide and formoterol were within 85%-115% of the label claim for each strength of DuoResp Spiromax for initial dose uniformity and for the other investigated conditions (temperature, humidity, orientation, dropping, knocking), with the exception of approximately an 80% increase in first dose after dropping the inhaler (subsequent doses not affected). In the flow rate patient study, two patients' inhalations with Spiromax and six with Turbuhaler were <30 L/min. The majority of asthma patients [91% (Spiromax) versus 82% (Turbuhaler)] achieved the preferred flow rate of >60 L/min. DuoResp Spiromax consistently meets dose uniformity criteria, under controlled laboratory conditions and with variations intended to mimic real-world use. Following enhanced training, all patients in the flow study were able to achieve the minimal inspiratory flow rate of >30 L/min, which is required for effective treatment.

Tearing Instability of a Current Sheet Forming by Sheared Incompressible Flow

NASA Astrophysics Data System (ADS)

Tolman, Elizabeth; Loureiro, Nuno; Uzdensky, Dmitri

2017-10-01

Sweet-Parker current sheets are unstable to the tearing mode, suggesting they will not form in physical systems. Understanding magnetic reconnection thus requires study of the stability of a current sheet as it forms. Such formation can occur as a result of sheared, sub-Alfvénic incompressible flows into and along the sheet. This work presents an analysis of how tearing perturbations behave in a current sheet forming under the influence of such flows, beginning with a phase when the growth rate of the tearing mode is small and the behavior of perturbations is primarily governed by ideal MHD. Later, after the tearing growth rate becomes significant relative to the time scale of the driving flows, the flows cause a slight reduction in the tearing growth rate and wave vector of the dominant mode. Once the tearing mode enters the nonlinear regime, the flows accelerate the tearing growth slightly; during X-point collapse, the flows have negligible effect on the system behavior. This analysis allows greater understanding of reconnection in evolving systems and increases confidence in the application of tools developed in time-independent current sheets to changing current sheets. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship.

The effect of reduced gravity on cryogenic nitrogen boiling and pipe chilldown.

PubMed

Darr, Samuel; Dong, Jun; Glikin, Neil; Hartwig, Jason; Majumdar, Alok; Leclair, Andre; Chung, Jacob

2016-01-01

Manned deep space exploration will require cryogenic in-space propulsion. Yet, accurate prediction of cryogenic pipe flow boiling heat transfer is lacking, due to the absence of a cohesive reduced gravity data set covering the expected flow and thermodynamic parameter ranges needed to validate cryogenic two-phase heat transfer models. This work provides a wide range of cryogenic chilldown data aboard an aircraft flying parabolic trajectories to simulate reduced gravity. Liquid nitrogen is used to quench a 1.27 cm diameter tube from room temperature. The pressure, temperature, flow rate, and inlet conditions are reported from 10 tests covering liquid Reynolds number from 2,000 to 80,000 and pressures from 80 to 810 kPa. Corresponding terrestrial gravity tests were performed in upward, downward, and horizontal flow configurations to identify gravity and flow direction effects on chilldown. Film boiling heat transfer was lessened by up to 25% in reduced gravity, resulting in longer time and more liquid to quench the pipe to liquid temperatures. Heat transfer was enhanced by increasing the flow rate, and differences between reduced and terrestrial gravity diminished at high flow rates. The new data set will enable the development of accurate and robust heat transfer models of cryogenic pipe chilldown in reduced gravity.

The effect of reduced gravity on cryogenic nitrogen boiling and pipe chilldown

PubMed Central

Darr, Samuel; Dong, Jun; Glikin, Neil; Hartwig, Jason; Majumdar, Alok; Leclair, Andre; Chung, Jacob

2016-01-01

Manned deep space exploration will require cryogenic in-space propulsion. Yet, accurate prediction of cryogenic pipe flow boiling heat transfer is lacking, due to the absence of a cohesive reduced gravity data set covering the expected flow and thermodynamic parameter ranges needed to validate cryogenic two-phase heat transfer models. This work provides a wide range of cryogenic chilldown data aboard an aircraft flying parabolic trajectories to simulate reduced gravity. Liquid nitrogen is used to quench a 1.27 cm diameter tube from room temperature. The pressure, temperature, flow rate, and inlet conditions are reported from 10 tests covering liquid Reynolds number from 2,000 to 80,000 and pressures from 80 to 810 kPa. Corresponding terrestrial gravity tests were performed in upward, downward, and horizontal flow configurations to identify gravity and flow direction effects on chilldown. Film boiling heat transfer was lessened by up to 25% in reduced gravity, resulting in longer time and more liquid to quench the pipe to liquid temperatures. Heat transfer was enhanced by increasing the flow rate, and differences between reduced and terrestrial gravity diminished at high flow rates. The new data set will enable the development of accurate and robust heat transfer models of cryogenic pipe chilldown in reduced gravity. PMID:28725740

Implementation of two-component advective flow solution in XSPEC

NASA Astrophysics Data System (ADS)

Debnath, Dipak; Chakrabarti, Sandip K.; Mondal, Santanu

2014-05-01

Spectral and temporal properties of black hole candidates can be explained reasonably well using Chakrabarti-Titarchuk solution of two-component advective flow (TCAF). This model requires two accretion rates, namely the Keplerian disc accretion rate and the halo accretion rate, the latter being composed of a sub-Keplerian, low-angular-momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disc rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time, we made it user friendly by implementing it into XSPEC software of Goddard Space Flight Center (GSFC)/NASA. This enables any user to extract physical parameters of the accretion flows, such as two accretion rates, the shock location, the shock strength, etc., for any black hole candidate. We provide some examples of fitting a few cases using this model. Most importantly, unlike any other model, we show that TCAF is capable of predicting timing properties from the spectral fits, since in TCAF, a shock is responsible for deciding spectral slopes as well as quasi-periodic oscillation frequencies. L86

Development of a 13 kW Hall Thruster Propulsion System Performance Model for AEPS

NASA Technical Reports Server (NTRS)

Stanley, Steven; Allen, May; Goodfellow, Keith; Chew, Gilbert; Rapetti, Ryan; Tofil, Todd; Herman, Dan; Jackson, Jerry; Myers, Roger

2017-01-01

The Advanced Electric Propulsion System (AEPS) program will develop a flight 13kW Hall thruster propulsion system based on NASA's HERMeS thruster. The AEPS system includes the Hall Thruster, the Power Processing Unit (PPU) and the Xenon Flow Controller (XFC). These three primary components must operate together to ensure that the system generates the required combinations of thrust and specific impulse at the required system efficiencies for the desired system lifetime. At the highest level, the AEPS system will be integrated into the spacecraft and will receive power, propellant, and commands from the spacecraft. Power and propellant flow rates will be determined by the throttle set points commanded by the spacecraft. Within the system, the major control loop is between the mass flow rate and thruster current, with time-dependencies required to handle all expected transients, and additional, much slower interactions between the thruster and cathode temperatures, flow controller and PPU. The internal system interactions generally occur on shorter timescales than the spacecraft interactions, though certain failure modes may require rapid responses from the spacecraft. The AEPS system performance model is designed to account for all these interactions in a way that allows evaluation of the sensitivity of the system to expected changes over the planned mission as well as to assess the impacts of normal component and assembly variability during the production phase of the program. This effort describes the plan for the system performance model development, correlation to NASA test data, and how the model will be used to evaluate the critical internal and external interactions. The results will ensure the component requirements do not unnecessarily drive the system cost or overly constrain the development program. Finally, the model will be available to quickly troubleshoot any future unforeseen development challenges.

Evaluations of the Combat Ready Clamp to Control Bleeding in Human Cadavers, Manikins, Swine Femoral Artery Hemorrhage Model and Swine Carcasses

DTIC Science & Technology

2012-06-01

some advantages over alternative live tissue models when a mechanical device is employed to reduce arterial flow rates. Authentic human anatomy is...vessels to reduce and stop blood flow require authentic human anatomy for optimal testing. Cadaver I was approximately 60 year old male with a total

Measurement of OH, O, and NO densities and their correlations with mouse melanoma cell death rate treated by a nanosecond pulsed streamer discharge

NASA Astrophysics Data System (ADS)

Yagi, Ippei; Shirakawa, Yuki; Hirakata, Kenta; Akiyama, Taketoshi; Yonemori, Seiya; Mizuno, Kazue; Ono, Ryo; Oda, Tetsuji

2015-10-01

Mouse melanoma cells in a culture medium are treated using a nanosecond pulsed streamer discharge plasma and the correlations between the rate of cell death and the densities of reactive species (OH, O, and NO) in the plasma are measured. The plasma is irradiated onto the culture medium surface with a vertical gas flow of an O2/N2 mixture from a glass tube at various gas flow rates and O2 concentrations. The densities of the reactive species are measured very close to the culture medium surface, where the reactive species interact with the culture medium, using laser-induced fluorescence. In the case of the N2 discharge (O2 = 0%), an increase in gas flow rate decreases OH density because it lowers the water vapor concentration by diluting the vapor, which is required for OH production. The increase in gas flow rate also leads to a decreased cell death rate. In the case of the O2/N2 discharge, on the other hand, an increase in O2 concentration at a fixed flow rate does not affect the rate of cell death, although it considerably changes the O and NO densities. These findings indicate that some reactive species derived from water vapor such as OH are responsible for the melanoma cell death, whereas those from O2, such as O and NO, are less likely responsible. They also indicate the importance of water evaporation from the culture medium surface in cell treatment.

Migration of Amphitheater-Headed Valleys in Kauai Basalts: Wailua Falls as a Case Example

NASA Astrophysics Data System (ADS)

Pederson, D. T.; Blay, C.

2006-12-01

Amphitheater-headed valleys in Kauai basalts migrate upstream primarily because of weathering processes. Basalt weathering rates are enhanced by the presence of water and/or vegetation. When both weathering process are present, weathering rates are greater than the sum of the two processes. Because waterfalls can create an environment where vegetation growth is greatly inhibited by the impact of falling water, weathering rates may be much greater on each side of the falls where vegetation can grow. Sources of water for weathering include groundwater discharge, waterfall spray, and condensation of atmospheric water. Because basalts weather rapidly in tropical environments, streams require only the capability to transport smaller particle sizes to sustain amphitheater migration. It should be noted that most waterfalls occupy only a small fraction of the amphitheater head which further supports weathering as the principal agent in amphitheater development and migration. Lava flows building shield volcanos are usually episodic with crystallization and possible weathering occurring before the next flow. The rate of cooling of a flow determines the crystal size of minerals and in combination with the magma chemistry the susceptibility of a flow to weathering process as well as the strength of the rock. With time, soils and topography will develop on the now crystallized flow. Because clays are a product of basalt weathering, soils when buried by later flows, represent low permeability layers. Additionally, new flows may follow (and bury) surface drainage systems resulting in localized thicker flows that cool more slowly and have different properties then the adjacent thinner flows. Consequently, most amphitheater heads have significant heterogenieties, especially in a vertical section representing multiple basalt flows. Wailua Falls on Kauai will be used as a field example of amphitheater weathering processes and migration.

An investigation of deformation and fluid flow at subduction zones using newly developed instrumentation and finite element modeling

NASA Astrophysics Data System (ADS)

Labonte, Alison Louise

Detecting seafloor deformation events in the offshore convergent margin environment is of particular importance considering the significant seismic hazard at subduction zones. Efforts to gain insight into the earthquake cycle have been made at the Cascadia and Costa Rica subduction margins through recent expansions of onshore GPS and seismic networks. While these studies have given scientists the ability to quantify and locate slip events in the seismogenic zone, there is little technology available for adequately measuring offshore aseismic slip. This dissertation introduces an improved flow meter for detecting seismic and aseismic deformation in submarine environments. The value of such hydrologic measurements for quantifying the geodetics at offshore margins is verified through a finite element modeling (FEM) study in which the character of deformation in the shallow subduction zone is determined from previously recorded hydrologic events at the Costa Rica Pacific margin. Accurately sensing aseismic events is one key to determining the stress state in subduction zones as these slow-slip events act to load or unload the seismogenic zone during the interseismic period. One method for detecting seismic and aseismic strain events is to monitor the hydrogeologic response to strain events using fluid flow meters. Previous instrumentation, the Chemical Aqueous Transport (CAT) meter which measures flow rates through the sediment-water interface, can detect transient events at very low flowrates, down to 0.0001 m/yr. The CAT meter performs well in low flow rate environments and can capture gradual changes in flow rate, as might be expected during ultra slow slip events. However, it cannot accurately quantify high flow rates through fractures and conduits, nor does it have the temporal resolution and accuracy required for detecting transient flow events associated with rapid deformation. The Optical Tracer Injection System (OTIS) developed for this purpose is an electronic flow meter that can measure flow rates of 0.1 to >500 m/yr at a temporal resolution of 30 minutes to 0.5 minutes, respectively. Test deployments of the OTIS at cold seeps in the transpressional Monterey Bay demonstrated the OTIS functionality over this range of flow environments. Although no deformation events were detected during these test deployments, the OTIS's temporally accurate measurements at the vigorously flowing Monterey Bay cold seep rendered valuable insight into the plumbing of the seep system. In addition to the capability to detect transient flow events, a primary functional requirement of the OTIS was the ability to communicate and transfer data for long-term real-time monitoring deployments. Real-time data transfer from the OTIS to the desktop was successful during a test deployment of the Nootka Observatory, an acoustically-linked moored-buoy system. A small array of CAT meters was also deployed at the Nootka transform-Cascadia subduction zone triple junction. Four anomalous flow rate events were observed across all four meters during the yearlong deployment. Although the records have low temporal accuracy, a preliminary explanation for the regional changes in flow rate is made through comparison between flow rate records and seismic records. The flow events are thought to be a result of a tectonic deformation event, possibly with an aseismic component. Further constraints are not feasible given the unknown structure of faulting near the triple junction. In a final proof of concept study, I find that use these hydrologic instruments, which capture unique aseismic flow rate patterns, is a valuable method for extracting information about deformation events on the decollement in the offshore subduction zone margin. Transient flow events observed in the frontal prism during a 1999--2000 deployment of CAT meters on the Costa Rica Pacific margin suggest episodic slow-slip deformation events may be occurring in the shallow subduction zone. The FEM study to infer the character of the hypothetical deformation event driving flow transients verify that indeed, a shallow slow-slip event can reproduce the unique flow rate patterns observed. Along (trench) strike variability in the rupture initiation location, and bidirectional propagation, is one way to explain the opposite sign of flow rate transients observed at different along-strike distances. The larger question stimulated by this dissertation project, is: What are the controls on fault mechanics in offshore subduction zone environments? It appears the shallow subduction zone plate interface doesn't behave solely in response to frictional properties of the sediment lining the decollement. Shallow episodic slip at the Costa Rica Pacific margin and further north off Nicaragua, where a slow earthquake broke through the shallow 'stable-sliding' zone and resulted in a tsunami, are potentially conceived through the normally faulted incoming basement topography. Scientists should seek to map out the controls of faulting mechanics, whatever they may be, at all temporal and spatial scales in order to understand these dynamic subduction zone systems. The quest to understanding these controls, in part, requires the characterization of aseismic and seismic strain occurring over time and space. The techniques presented in this dissertation advance scientists' capability for quantifying such strains. With the new instrumentation presented here, long-term real-time observatory networks on the seafloor, and modeling for characterization of deformation events, the pieces of the subduction zone earthquake cycle puzzle may start to come together.

Tolerance requirements to prevent fluid leakage in the crucible/plunger MEA experiment MPS 770030

NASA Technical Reports Server (NTRS)

Rathz, T. J.

1982-01-01

Molten Al-In leaked unexpectedly out of the crucible of a proposed MEA materials processing in space experiment. The molten metals use a spring loaded plunger to eliminate most free surfaces. The critical criteria necessary to initiate flow and the rate of fluid flow into the crucible/plunger annulus is calculated. Experimental in situ X-radiographs are interpreted according to the calculations. A note on possible effects of capillary flow if wetting occurs between crucible/plunger and liquids is included.

Pico-CSIA: Picomolar Scale Compound-Specific Isotope Analyses

NASA Astrophysics Data System (ADS)

Baczynski, A. A.; Polissar, P. J.; Juchelka, D.; Schwieters, J. B.; Hilkert, A.; Freeman, K. H.

2016-12-01

The basic approach to analyzing molecular isotopes has remained largely unchanged since the late 1990s. Conventional compound-specific isotope analyses (CSIA) are conducted using capillary gas chromatography (GC), a combustion interface, and an isotope-ratio mass spectrometer (IRMS). Commercially available GC-IRMS systems are comprised of components with inner diameters ≥0.25 mm and employ helium flow rates of 1-4 mL/min. These flow rates are an order of magnitude larger than what the IRMS can accept. Consequently, ≥90% of the sample is lost through the open split, and 1-10s of nanomoles of carbon are required for analysis. These sample requirements are prohibitive for many biomarkers, which are often present in picomolar concentrations. We utilize the resolving power and low flows of narrow-bore capillary GC to improve the sensitivity of CSIA. Narrow bore capillary columns (<0.25 mm ID) allow low helium flow rates of ≤0.5mL/min for more efficient sample transfer to the ion source of the IRMS while maintaining the high linear flow rates necessary to preserve narrow peak widths ( 250 ms). The IRMS has been fitted with collector amplifiers configured to 25 ms response times for rapid data acquisition across narrow peaks. Previous authors (e.g., Sacks et al., 2007) successfully demonstrated improved sensitivity afforded by narrow-bore GC columns. They reported an accuracy and precision of 1.4‰ for peaks with an average width at half maximum of 720 ms for 100 picomoles of carbon on column. Our method builds on their advances and further reduces peak widths ( 600 ms) and the amount of sample lost prior to isotopic analysis. Preliminary experiments with 100 picomoles of carbon on column show an accuracy and standard deviation <1‰. With further improvement, we hope to demonstrate robust isotopic analysis of 10s of picomoles of carbon, more than 2 orders of magnitude lower than commercial systems. The pico-CSIA method affords high-precision isotopic analyses for picomoles of carbon in organic biomarkers, which significantly lowers sample size requirements and broadens analytical windows in paleoclimate, astrobiological, and biogeochemical research.

Tuning-free controller to accurately regulate flow rates in a microfluidic network

NASA Astrophysics Data System (ADS)

Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

2016-03-01

We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework.

Tuning-free controller to accurately regulate flow rates in a microfluidic network

PubMed Central

Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

2016-01-01

We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework. PMID:26987587

A High Performance Pulsatile Pump for Aortic Flow Experiments in 3-Dimensional Models.

PubMed

Chaudhury, Rafeed A; Atlasman, Victor; Pathangey, Girish; Pracht, Nicholas; Adrian, Ronald J; Frakes, David H

2016-06-01

Aortic pathologies such as coarctation, dissection, and aneurysm represent a particularly emergent class of cardiovascular diseases. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies, as well as for planning their surgical repair. In vitro experiments are required to validate the simulations against real world data, and the experiments require a pulsatile flow pump system that can provide physiologic flow conditions characteristic of the aorta. We designed a newly capable piston-based pulsatile flow pump system that can generate high volume flow rates (850 mL/s), replicate physiologic waveforms, and pump high viscosity fluids against large impedances. The system is also compatible with a broad range of fluid types, and is operable in magnetic resonance imaging environments. Performance of the system was validated using image processing-based analysis of piston motion as well as particle image velocimetry. The new system represents a more capable pumping solution for aortic flow experiments than other available designs, and can be manufactured at a relatively low cost.

Reacting flow studies in a dump combustor: Enhanced volumetric heat release rates and flame anchorability

NASA Astrophysics Data System (ADS)

Behrens, Alison Anne

Reacting flow studies in a novel dump combustor facility focused on increasing volumetric heat release rates, under stable burning conditions, and understanding the physical mechanisms governing flame anchoring in an effort to extend range and maneuverability of compact, low drag, air-breathing engines. Countercurrent shear flow was enhanced within the combustor as the primary control variable. Experiments were performed burning premixed JP10/air and methane/air in a dump combustor using reacting flow particle image velocimetry (PIV) and chemiluminescence as the primary diagnostics. Stable combustion studies burning lean mixtures of JP10/air aimed to increase volumetric heat release rates through the implementation of countercurrent shear control. Countercurrent shear flow was produced by creating a suction flow from a low pressure cavity connected to the dump combustor via a gap directly below the trailing edge. Chemiluminescence measurements showed that enhancing countercurrent shear within the combustor doubles volumetric heat release rates. PIV measurements indicate that counterflow acts to increase turbulent kinetic energy while maintaining constant strain rates. This acts to increase flame surface area through flame wrinkling without disrupting the integrity of the flame. Flame anchorability is one of the most important fundamental aspects to understand when trying to enhance turbulent combustion in a high-speed engine without increasing drag. Studies burning methane/air mixtures used reacting flow PIV to study flame anchoring. The operating point with the most stable flame anchor exhibited a correspondingly strong enthalpy flux of products into reactants via a single coherent structure positioned downstream of the step. However, the feature producing a strong flame anchor, i.e. a single coherent structure, also is responsible for combustion instabilities, therefore making this operating point undesirable. Counterflow control was found to create the best flow features for stable, robust, compact combustion. Enhancing countercurrent shear flow within a dump combustor enhances burning rates, provides a consistent pump of reaction-initiating combustion products required for sustained combustion, while maintaining flow three dimensionality needed to disrupt combustion instabilities. Future studies will focus on geometric and control scenarios that further reduce drag penalties while creating these same flow features found with countercurrent shear thus producing robust operating points.

A Novel Low-Power, High-Performance, Zero-Maintenance Closed-Path Trace Gas Eddy Covariance System with No Water Vapor Dilution or Spectroscopic Corrections

NASA Astrophysics Data System (ADS)

Sargent, S.; Somers, J. M.

2015-12-01

Trace-gas eddy covariance flux measurement can be made with open-path or closed-path analyzers. Traditional closed-path trace-gas analyzers use multipass absorption cells that behave as mixing volumes, requiring high sample flow rates to achieve useful frequency response. The high sample flow rate and the need to keep the multipass cell extremely clean dictates the use of a fine-pore filter that may clog quickly. A large-capacity filter cannot be used because it would degrade the EC system frequency response. The high flow rate also requires a powerful vacuum pump, which will typically consume on the order of 1000 W. The analyzer must measure water vapor for spectroscopic and dilution corrections. Open-path analyzers are available for methane, but not for nitrous oxide. The currently available methane analyzers have low power consumption, but are very large. Their large size degrades frequency response and disturbs the air flow near the sonic anemometer. They require significant maintenance to keep the exposed multipass optical surfaces clean. Water vapor measurements for dilution and spectroscopic corrections require a separate water vapor analyzer. A new closed-path eddy covariance system for measuring nitrous oxide or methane fluxes provides an elegant solution. The analyzer (TGA200A, Campbell Scientific, Inc.) uses a thermoelectrically-cooled interband cascade laser. Its small sample-cell volume and unique sample-cell configuration (200 ml, 1.5 m single pass) provide excellent frequency response with a low-power scroll pump (240 W). A new single-tube Nafion® dryer removes most of the water vapor, and attenuates fluctuations in the residual water vapor. Finally, a vortex intake assembly eliminates the need for an intake filter without adding volume that would degrade system frequency response. Laboratory testing shows the system attenuates the water vapor dilution term by more than 99% and achieves a half-power band width of 3.5 Hz.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, R.F.; Dietrich, D.D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability is disclosed. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three. 6 figs.

40 CFR 61.24 - Annual reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., including their location, diameter, flow rate, effluent temperature and release height. (5) A description of...) Distances from the points of release to the nearest residence, school, business or office and the nearest...

Fluid-dynamic design optimization of hydraulic proportional directional valves

NASA Astrophysics Data System (ADS)

Amirante, Riccardo; Catalano, Luciano Andrea; Poloni, Carlo; Tamburrano, Paolo

2014-10-01

This article proposes an effective methodology for the fluid-dynamic design optimization of the sliding spool of a hydraulic proportional directional valve: the goal is the minimization of the flow force at a prescribed flow rate, so as to reduce the required opening force while keeping the operation features unchanged. A full three-dimensional model of the flow field within the valve is employed to accurately predict the flow force acting on the spool. A theoretical analysis, based on both the axial momentum equation and flow simulations, is conducted to define the design parameters, which need to be properly selected in order to reduce the flow force without significantly affecting the flow rate. A genetic algorithm, coupled with a computational fluid dynamics flow solver, is employed to minimize the flow force acting on the valve spool at the maximum opening. A comparison with a typical single-objective optimization algorithm is performed to evaluate performance and effectiveness of the employed genetic algorithm. The optimized spool develops a maximum flow force which is smaller than that produced by the commercially available valve, mainly due to some major modifications occurring in the discharge section. Reducing the flow force and thus the electromagnetic force exerted by the solenoid actuators allows the operational range of direct (single-stage) driven valves to be enlarged.

40 CFR 60.4870 - How do I establish my operating limits?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Sewage Sludge Incineration Units Initial Compliance Requirements § 60.4870 How do I establish my... compliance with the emission limit for particulate matter, cadmium, and lead. (4) For an activated carbon... limit and monitor sorbent injection rate and carrier gas flow rate (or carrier gas pressure drop) if you...

40 CFR 60.4870 - How do I establish my operating limits?

Code of Federal Regulations, 2012 CFR

2012-07-01

... Sewage Sludge Incineration Units Initial Compliance Requirements § 60.4870 How do I establish my... compliance with the emission limit for particulate matter, cadmium, and lead. (4) For an activated carbon... limit and monitor sorbent injection rate and carrier gas flow rate (or carrier gas pressure drop) if you...

40 CFR 60.4870 - How do I establish my operating limits?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Sewage Sludge Incineration Units Initial Compliance Requirements § 60.4870 How do I establish my... compliance with the emission limit for particulate matter, cadmium, and lead. (4) For an activated carbon... limit and monitor sorbent injection rate and carrier gas flow rate (or carrier gas pressure drop) if you...

40 CFR 60.4870 - How do I establish my operating limits?

Code of Federal Regulations, 2013 CFR

2013-07-01

... Sewage Sludge Incineration Units Initial Compliance Requirements § 60.4870 How do I establish my... compliance with the emission limit for particulate matter, cadmium, and lead. (4) For an activated carbon... limit and monitor sorbent injection rate and carrier gas flow rate (or carrier gas pressure drop) if you...

Fabrication and Testing of Tapered Electro-spray Nozzles

DTIC Science & Technology

2012-09-01

4.2 Microclimate Issues .......................................................................................................20 5. Summary and...requirement, while using very low flow rates per nozzle to obtain small combustor geometries. 4.2 Microclimate One of the challenges with this...off the Taylor-cone. To determine if there is an influence of microclimate , the evaporation rate was calculated from the Langmuir equation 1, using

40 CFR 63.1429 - Process vent monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the presence of a pilot flame. (3) Where a boiler or process heater of less than 44 megawatts design... series are used, a scrubbing liquid flow rate meter, or a pressure monitoring device, equipped with a continuous recorder, is required for each absorber in the series. An owner or operator may submit a request...

40 CFR 63.1429 - Process vent monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the presence of a pilot flame. (3) Where a boiler or process heater of less than 44 megawatts design... series are used, a scrubbing liquid flow rate meter, or a pressure monitoring device, equipped with a continuous recorder, is required for each absorber in the series. An owner or operator may submit a request...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2010 CFR

2010-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2011 CFR

2011-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2013 CFR

2013-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2014 CFR

2014-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2012 CFR

2012-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 60.5225 - What are the monitoring and calibration requirements for compliance with my operating limits?

Code of Federal Regulations, 2012 CFR

2012-07-01

... SOURCES Emission Guidelines and Compliance Times for Existing Sewage Sludge Incineration Units Model Rule... monitoring system according to your monitoring plan required under § 60.4880. Additionally: (i) For carrier gas flow rate monitors (for activated carbon injection), during the performance test conducted...

40 CFR 75.74 - Annual and ozone season monitoring and reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... owner or operator of an affected unit subject both to an Acid Rain emission limitation and to a State or... State or federal NOX mass reduction program that adopts the provisions of this part and that requires...-diluent monitoring system, each flow rate monitoring system, each moisture monitoring system and each...

Simulating Nailfold Capillaroscopy Sequences to Evaluate Algorithms for Blood Flow Estimation

PubMed Central

Tresadern, P. A.; Berks, M.; Murray, A. K.; Dinsdale, G.; Taylor, C. J.; Herrick, A. L.

2016-01-01

The effects of systemic sclerosis (SSc) – a disease of the connective tissue causing blood flow problems that can require amputation of the fingers – can be observed indirectly by imaging the capillaries at the nailfold, though taking quantitative measures such as blood flow to diagnose the disease and monitor its progression is not easy. Optical flow algorithms may be applied, though without ground truth (i.e. known blood flow) it is hard to evaluate their accuracy. We propose an image model that generates realistic capillaroscopy videos with known flow, and use this model to quantify the effect of flow rate, cell density and contrast (among others) on estimated flow. This resource will help researchers to design systems that are robust under real-world conditions. PMID:24110268

Slugging Flow of Water Draining from the Bottom of a Non-Vented Container

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles W. Solbrig

2010-06-01

Experiments were run to observe the behavior of water exiting through an orifice at the bottom of an non-vented container. Initially, the container is nearly full of water with a small air space on top. Once the orifice was uncovered, the slugging rate and the drain rate of the water leaving the container were measured. Upon initially opening the orifice, water drains out until the air pressure above the water reduces enough that the air pressure drop from inside to outside of the container supports the water column and the water stops flowing. Air then enters the container through themore » orifice forming a bubble, which grows until it detaches and bubbles through the water to reach the air space. Once the bubble enters, this added air increases the pressure in the air space enough to allow the water to start flowing out again. This cycle of flow out, flow stoppage, air inflow, and bubble breakoff continues over and over until the hole is closed or the container empties. This is referred to as the “slugging cycle.” A mechanism is proposed to describe the slugging cycle which is modeled analytically. This paper presents the description of the experiments, data obtained, the mechanistic model, and comparison of the model to the experimental data. The model predicts outflow rates close to experimental values. Flow rates from non-vented containers are more than 10 to 20 less than vented containers. The bubbles which must enter the container periodically to increase the internal air pressure stop the water flow momentarily so are responsible for this large decrease in flow rate. Swirl induced in the non-vented container causes the flow rates to increase by a factor of two. The flow rate out of a non-vented container is independent of water height which is in direct contrast to a vented container where the flow rate is proportional to the square root of the water height. The constant rate is due to the container pressure. The higher the water level, the lower the air pressure is in the container. This analytical model requires input of the bubble size. The volume recommended is the volume of a cylinder with the base of the orifice area and length of 3.3 cm. Slugging rate varies only a small amount falling in the range to 2 to 4 cycles/sec. Preliminary work with other containers indicates larger containers, larger orifices and nozzle exit shapes produce higher specific flow rates. The standard multiphase flow equations could not be used to analyze this situation because the two phases are not interpenetrating. Instead one phase must fully stop before the other can flow. Interpenetrating phases allow can pass one another each affecting the other with friction and virtual mass. An interesting observation: The negative air pressure in the container is observable. It equals the water height.« less

Aortic Wave Dynamics and Its Influence on Left Ventricular Workload

PubMed Central

Pahlevan, Niema M.; Gharib, Morteza

2011-01-01

The pumping mechanism of the heart is pulsatile, so the heart generates pulsatile flow that enters into the compliant aorta in the form of pressure and flow waves. We hypothesized that there exists a specific heart rate at which the external left ventricular (LV) power is minimized. To test this hypothesis, we used a computational model to explore the effects of heart rate (HR) and aortic rigidity on left ventricular (LV) power requirement. While both mean and pulsatile parts of the pressure play an important role in LV power requirement elevation, at higher rigidities the effect of pulsatility becomes more dominant. For any given aortic rigidity, there exists an optimum HR that minimizes the LV power requirement at a given cardiac output. The optimum HR shifts to higher values as the aorta becomes more rigid. To conclude, there is an optimum condition for aortic waves that minimizes the LV pulsatile load and consequently the total LV workload. PMID:21853075

River flow maintenance turbine for Milner Hydroelectric Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carson, J.L.; Holveck, W.H.; Gokhman, A.

1995-12-31

The Milner Hydroelectric Project on the Snake River in Idaho was commissioned in 1992. The project included renovation of an existing dam, which was built to supply irrigation water to a canal system, construction of a new spillway, and the addition of a new powerhouse. The forebay of the main powerhouse is located on a combination power and irrigation canal, approximately 3500 feet (1070 m) from the dam, with a short tailrace returning the water to the river. There are two Kaplan turbines installed in the main powerhouse, rated at 1000 cfs and 4000 cfs respectively at a net headmore » of 150 feet. The FERC license required that a target flow of 200 cfs be released from the dam to maintain a stream flow between the dam and the powerhouse. In order to utilize this flow, a small powerhouse was constructed at the toe of the dam. The site conditions favored a vertical axial flow turbine, with a net head of 56 feet. As the flow is constant and the head is fairly constant, a fixed geometry turbine was selected, to be controlled solely by the intake gate. Due to the higher head, the main powerhouse can generate more power per unit of flow than can the bypass turbine. Therefore, it is undesirable for the discharge of the bypass turbine to be any greater than required by the license. Also, the release flow is determined by a river gauge, the accuracy of which is unknown, but assumed to be within five percent. In order to meet these two requirements, the turbine was specified to have manually adjustable runner blades to obtain the required release flow of 200 cfs at any head between 55 and 58 feet.« less

40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

Code of Federal Regulations, 2011 CFR

2011-07-01

... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

Code of Federal Regulations, 2010 CFR

2010-07-01

... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

Code of Federal Regulations, 2012 CFR

2012-07-01

... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

Code of Federal Regulations, 2013 CFR

2013-07-01

... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

Code of Federal Regulations, 2014 CFR

2014-07-01

... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

Catch bonds govern adhesion through L-selectin at threshold shear.

PubMed

Yago, Tadayuki; Wu, Jianhua; Wey, C Diana; Klopocki, Arkadiusz G; Zhu, Cheng; McEver, Rodger P

2004-09-13

Flow-enhanced cell adhesion is an unexplained phenomenon that might result from a transport-dependent increase in on-rates or a force-dependent decrease in off-rates of adhesive bonds. L-selectin requires a threshold shear to support leukocyte rolling on P-selectin glycoprotein ligand-1 (PSGL-1) and other vascular ligands. Low forces decrease L-selectin-PSGL-1 off-rates (catch bonds), whereas higher forces increase off-rates (slip bonds). We determined that a force-dependent decrease in off-rates dictated flow-enhanced rolling of L-selectin-bearing microspheres or neutrophils on PSGL-1. Catch bonds enabled increasing force to convert short-lived tethers into longer-lived tethers, which decreased rolling velocities and increased the regularity of rolling steps as shear rose from the threshold to an optimal value. As shear increased above the optimum, transitions to slip bonds shortened tether lifetimes, which increased rolling velocities and decreased rolling regularity. Thus, force-dependent alterations of bond lifetimes govern L-selectin-dependent cell adhesion below and above the shear optimum. These findings establish the first biological function for catch bonds as a mechanism for flow-enhanced cell adhesion.

Flow rate of transport network controls uniform metabolite supply to tissue

PubMed Central

Meigel, Felix J.

2018-01-01

Life and functioning of higher organisms depends on the continuous supply of metabolites to tissues and organs. What are the requirements on the transport network pervading a tissue to provide a uniform supply of nutrients, minerals or hormones? To theoretically answer this question, we present an analytical scaling argument and numerical simulations on how flow dynamics and network architecture control active spread and uniform supply of metabolites by studying the example of xylem vessels in plants. We identify the fluid inflow rate as the key factor for uniform supply. While at low inflow rates metabolites are already exhausted close to flow inlets, too high inflow flushes metabolites through the network and deprives tissue close to inlets of supply. In between these two regimes, there exists an optimal inflow rate that yields a uniform supply of metabolites. We determine this optimal inflow analytically in quantitative agreement with numerical results. Optimizing network architecture by reducing the supply variance over all network tubes, we identify patterns of tube dilation or contraction that compensate sub-optimal supply for the case of too low or too high inflow rate. PMID:29720455

Space-Time Dependent Transport, Activation, and Dose Rates for Radioactivated Fluids.

NASA Astrophysics Data System (ADS)

Gavazza, Sergio

Two methods are developed to calculate the space - and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates generated from the radioactivated fluids flowing through pipes. The work couples space- and time-dependent phenomena, treated as only space- or time-dependent in the open literature. The transport and activation methodology (TAM) is used to numerically calculate space- and time-dependent transport and activation of radionuclides in fluids flowing through pipes exposed to radiation fields, and volumetric radioactive sources created by radionuclide motions. The computer program Radionuclide Activation and Transport in Pipe (RNATPA1) performs the numerical calculations required in TAM. The gamma ray dose methodology (GAM) is used to numerically calculate space- and time-dependent gamma ray dose equivalent rates from the volumetric radioactive sources determined by TAM. The computer program Gamma Ray Dose Equivalent Rate (GRDOSER) performs the numerical calculations required in GAM. The scope of conditions considered by TAM and GAM herein include (a) laminar flow in straight pipe, (b)recirculating flow schemes, (c) time-independent fluid velocity distributions, (d) space-dependent monoenergetic neutron flux distribution, (e) space- and time-dependent activation process of a single parent nuclide and transport and decay of a single daughter radionuclide, and (f) assessment of space- and time-dependent gamma ray dose rates, outside the pipe, generated by the space- and time-dependent source term distributions inside of it. The methodologies, however, can be easily extended to include all the situations of interest for solving the phenomena addressed in this dissertation. A comparison is made from results obtained by the described calculational procedures with analytical expressions. The physics of the problems addressed by the new technique and the increased accuracy versus non -space and time-dependent methods are presented. The value of the methods is also discussed. It has been demonstrated that TAM and GAM can be used to enhance the understanding of the space- and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates related to radioactivated fluids flowing through pipes.

Transition of basaltic lava from pahoehoe to aa, Kilauea Volcano, Hawaii: Field observations and key factors

USGS Publications Warehouse

Peterson, Donald W.; Tilling, Robert I.

1980-01-01

Nearly all Hawaiian basaltic lava erupts as pahoehoe, and some changes to aa during flowage and cooling; factors governing the transition involve certain critical relations between viscosity and rate of shear strain. If the lava slows, cools, and stops in direct response to concomitant increase in viscosity before these critical relations are reached, it remains pahoehoe. But, if flow mechanics (flow rate, flow dimensions, slope, momentum, etc.) impel the lava to continue to move and deform even after it has become highly viscous, the critical relations may be reached and the lava changes to aa.Typical modes of transition from pahoehoe to aa include: (1) spontaneous formation of relatively stiff clots in parts of the flowing lava where shear rate is highest; these clots grow into discrete, rough, sticky masses to which the remaining fluid lava incrementally adheres; (2) fragmentation and immersion of solid or semi-solid surface crusts of pahoehoe by roiling movements of the flow, forming cores of discrete, tacky masses; (3) sudden renewed movement of lava stored and cooled within surface reservoirs to form clots. The masses, fragments, and clots in these transition modes are characterized by spinose, granulated surfaces; as flow movement continues, the masses and fragments aggregate, fracture, and grind together, completing the transition to aa.Observations show that the critical relation between viscosity and rate of shear strain is inverse: if viscosity is low, a high rate of shear is required to begin the transition to aa; conversely, if viscosity is high, a much lower rate of shear will induce the transition. These relations can be demonstrated qualitatively with simple graphs, which can be used to examine the flow history of any selected finite lava element by tracing the path represented by its changing viscosity and shear rate. A broad, diffuse “transition threshold zone” in these graphs portrays the inverse critical relation between viscosity and shear rate; the transition to aa is represented by the path of the lava element crossing this zone.Moving lava flows can be regarded as natural viscometers, by which shear stress and rate of shear strain at selected points can be determined and viscosity can be computed. By making such determinations under a wide range of conditions on pahoehoe, aa, and transitional flow types, the critical relations that control the pahoehoe-aa transition can be quantified.

Precision Adjustable Liquid Regulator (ALR)

NASA Astrophysics Data System (ADS)

Meinhold, R.; Parker, M.

2004-10-01

A passive mechanical regulator has been developed for the control of fuel or oxidizer flow to a 450N class bipropellant engine for use on commercial and interplanetary spacecraft. There are several potential benefits to the propulsion system, depending on mission requirements and spacecraft design. This system design enables more precise control of main engine mixture ratio and inlet pressure, and simplifies the pressurization system by transferring the function of main engine flow rate control from the pressurization/propellant tank assemblies, to a single component, the ALR. This design can also reduce the thermal control requirements on the propellant tanks, avoid costly Qualification testing of biprop engines for missions with more stringent requirements, and reduce the overall propulsion system mass and power usage. In order to realize these benefits, the ALR must meet stringent design requirements. The main advantage of this regulator over other units available in the market is that it can regulate about its nominal set point to within +/-0.85%, and change its regulation set point in flight +/-4% about that nominal point. The set point change is handled actively via a stepper motor driven actuator, which converts rotary into linear motion to affect the spring preload acting on the regulator. Once adjusted to a particular set point, the actuator remains in its final position unpowered, and the regulator passively maintains outlet pressure. The very precise outlet regulation pressure is possible due to new technology developed by Moog, Inc. which reduces typical regulator mechanical hysteresis to near zero. The ALR requirements specified an outlet pressure set point range from 225 to 255 psi, and equivalent water flow rates required were in the 0.17 lb/sec range. The regulation output pressure is maintained at +/-2 psi about the set point from a P (delta or differential pressure) of 20 to over 100 psid. Maximum upstream system pressure was specified at 320 psi. The regulator is fault tolerant in that it was purposely designed with no shutoff capability, such that the minimum flow position of the poppet still allows the subsystem to provide adequate flow to the main engine for basic operation.

Feasibility of a miniature centrifugal rotary blood pump for low-flow circulation in children and infants.

PubMed

Takatani, Setsuo; Hoshi, Hideo; Tajima, Kennichi; Ohuchi, Katsuhiro; Nakamura, Makoto; Asama, Junichio; Shimshi, Tadahiko; Yoshikawa, Masaharu

2005-01-01

In this study, a seal-less, tiny centrifugal rotary blood pump was designed for low-flow circulatory support in children and infants. The design was targeted to yield a compact and priming volume of 5 ml with a flow rate of 0.5-4 l/min against a head pressure of 40-100 mm Hg. To meet the design requirements, the first prototype had an impeller diameter of 30 mm with six straight vanes. The impeller was supported with a needle-type hydrodynamic bearing and was driven with a six-pole radial magnetic driver. The external pump dimensions included a pump head height of 20 mm, diameter of 49 mm, and priming volume of 5 ml. The weight was 150 g, including the motor driver. In the mock circulatory loop, using fresh porcine blood, the pump yielded a flow of 0.5-4.0 l/min against a head pressure of 40-100 mm Hg at a rotational speed of 1800-4000 rpm using 1/4" inflow and outflow conduits. The maximum flow and head pressure of 5.25 l/min and 244 mm Hg, respectively, were obtained at a rotational speed of 4400 rpm. The maximum electrical-to-hydraulic efficiency occurred at a flow rate of 1.5-3.5 l/min and at a rotational speed of 2000-4400 rpm. The normalized index of hemolysis, which was evaluated using fresh porcine blood, was 0.0076 g/100 l with the impeller in the down-mode and a bearing clearance of 0.1 mm. Further refinement in the bearing and magnetic coupler are required to improve the hemolytic performance of the pump. The durability of the needle-type hydrodynamic bearing and antithrombotic performance of the pump will be performed before clinical applications. The tiny centrifugal blood pump meets the flow requirements necessary to support the circulation of pediatric patients.

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs.

PubMed

Seymour, Roger S; Smith, Sarah L; White, Craig R; Henderson, Donald M; Schwarz-Wings, Daniela

2012-02-07

The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

PubMed Central

Seymour, Roger S.; Smith, Sarah L.; White, Craig R.; Henderson, Donald M.; Schwarz-Wings, Daniela

2012-01-01

The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat. PMID:21733896

Time-resolved PIV measurements of the flow field in a stenosed, compliant arterial model

NASA Astrophysics Data System (ADS)

Geoghegan, P. H.; Buchmann, N. A.; Soria, J.; Jermy, M. C.

2013-05-01

Compliant (flexible) structures play an important role in several biological flows including the lungs, heart and arteries. Coronary heart disease is caused by a constriction in the artery due to a build-up of atherosclerotic plaque. This plaque is also of major concern in the carotid artery which supplies blood to the brain. Blood flow within these arteries is strongly influenced by the movement of the wall. To study these problems experimentally in vitro, especially using flow visualisation techniques, can be expensive due to the high-intensity and high-repetition rate light sources required. In this work, time-resolved particle image velocimetry using a relatively low-cost light-emitting diode illumination system was applied to the study of a compliant flow phantom representing a stenosed (constricted) carotid artery experiencing a physiologically realistic flow wave. Dynamic similarity between in vivo and in vitro conditions was ensured in phantom construction by matching the distensibility and the elastic wave propagation wavelength and in the fluid system through matching Reynolds ( Re) and Womersley number ( α) with a maximum, minimum and mean Re of 939, 379 and 632, respectively, and a α of 4.54. The stenosis had a symmetric constriction of 50 % by diameter (75 % by area). Once the flow rate reached a critical value, Kelvin-Helmholtz instabilities were observed to occur in the shear layer between the main jet exiting the stenosis and a reverse flow region that occurred at a radial distance of 0.34 D from the axis of symmetry in the region on interest 0-2.5 D longitudinally downstream from the stenosis exit. The instability had an axis-symmetric nature, but as peak flow rate was approached this symmetry breaks down producing instability in the flow field. The characteristics of the vortex train were sensitive not only to the instantaneous flow rate, but also to whether the flow was accelerating or decelerating globally.

Physical aspects of computing the flow of a viscous fluid

NASA Technical Reports Server (NTRS)

Mehta, U. B.

1984-01-01

One of the main themes in fluid dynamics at present and in the future is going to be computational fluid dynamics with the primary focus on the determination of drag, flow separation, vortex flows, and unsteady flows. A computation of the flow of a viscous fluid requires an understanding and consideration of the physical aspects of the flow. This is done by identifying the flow regimes and the scales of fluid motion, and the sources of vorticity. Discussions of flow regimes deal with conditions of incompressibility, transitional and turbulent flows, Navier-Stokes and non-Navier-Stokes regimes, shock waves, and strain fields. Discussions of the scales of fluid motion consider transitional and turbulent flows, thin- and slender-shear layers, triple- and four-deck regions, viscous-inviscid interactions, shock waves, strain rates, and temporal scales. In addition, the significance and generation of vorticity are discussed. These physical aspects mainly guide computations of the flow of a viscous fluid.

Highly Sensitive Hot-Wire Anemometry Based on Macro-Sized Double-Walled Carbon Nanotube Strands.

PubMed

Wang, Dingqu; Xiong, Wei; Zhou, Zhaoying; Zhu, Rong; Yang, Xing; Li, Weihua; Jiang, Yueyuan; Zhang, Yajun

2017-08-01

This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs) as sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT) strands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor is demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by suspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of silver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive TCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current was applied between the two prongs. This sensor can evidently respond to flow rate, and requires only several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor has better sensitivity than the Pt-coated DWCNT sensor.

LOx breathing system with gas permeable-liquid impermeable heat exchange and delivery hose

DOEpatents

Hall, M.N.

1996-04-30

Life support apparatus is composed of: a garment for completely enclosing a wearer and constructed for preventing passage of gas from the environment surrounding the garment; a portable receptacle holding a quantity of an oxygen-containing fluid in liquid state, the fluid being in a breathable gaseous state when at standard temperature and pressure; a fluid flow member secured within the garment and coupled to the receptacle for conducting the fluid in liquid state from the receptacle to the interior of the garment; and a fluid flow control device connected for causing fluid to flow from the receptacle to the fluid flow member at a rate determined by the breathable air requirement of the wearer, wherein fluid in liquid state is conducted into the interior of the garment at a rate to be vaporized and heated to a breathable temperature by body heat produced by the wearer. 6 figs.

Note: Ultrasonic gas flowmeter based on optimized time-of-flight algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X. F.; Tang, Z. A.

2011-04-15

A new digital signal processor based single path ultrasonic gas flowmeter is designed, constructed, and experimentally tested. To achieve high accuracy measurements, an optimized ultrasound driven method of incorporation of the amplitude modulation and the phase modulation of the transmit-receive technique is used to stimulate the transmitter. Based on the regularities among the received envelope zero-crossings, different received signal's signal-to-noise ratio situations are discriminated and optional time-of-flight algorithms are applied to take flow rate calculations. Experimental results from the dry calibration indicate that the designed flowmeter prototype can meet the zero-flow verification test requirements of the American Gas Association Reportmore » No. 9. Furthermore, the results derived from the flow calibration prove that the proposed flowmeter prototype can measure flow rate accurately in the practical experiments, and the nominal accuracies after FWME adjustment are lower than 0.8% throughout the calibration range.« less

Critical parameters for coarse coal underground slurry haulage systems

NASA Technical Reports Server (NTRS)

Maynard, D. P.

1981-01-01

Factors are identified which must be considered in meeting the requirements of a transportation system for conveying, in a pipeline, the coal mined by a continuous mining machine to a storage location neat the mine entrance or to a coal preparation plant located near the surface. For successful operation, the slurry haulage the system should be designed to operated in the turbulent flow regime at a flow rate at least 30% greater than the deposition velocity (slurry flow rate at which the solid particles tend to settle in the pipe). The capacity of the haulage system should be compatible with the projected coal output. Partical size, solid concentration, density, and viscosity of the suspension are if importance as well as the selection of the pumps, pipes, and valves. The parameters with the greatest effect on system performance ar flow velocity, pressure coal particle size, and solids concentration.

Liquid Bismuth Propellant Management System for the Very High Specific Impulse Thruster with Anode Layer

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Markusic, T. E.; Stanojev, B. J.

2007-01-01

Two prototype bismuth propellant feed systems were constructed and operated in conjunction with a propellant vaporizer. One system provided bismuth to a vaporizer using gas pressurization but did not include a means to measure the flow rate. The second system incorporated an electromagnetic pump to provide fine control of the hydrostatic pressure and a new type of in-line flow sensor that was developed for accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of Macor for the main body of both components. Posttest inspections of both components revealed no degradation of the material. The gas pressurization system demonstrated continuous pressure control over a range from zero to 200 torr. In separate proof-of-concept experiments, the electromagnetic pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, producing a pressure rise of 10 kPa at 30 A. Preliminary flow sensor operation indicated a bismuth flow rate of 6 mg/s with an uncertainty of plus or minus 6%. An electronics suite containing a real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

Gravity flow operated small electricity generator retrofit kit to flour mill industry.

PubMed

Shekara, Prithivi; Kumar V, Pavan; Hosamane, Gangadharappa Gundabhakthara

2013-10-01

Flour milling is a grinding process to produce flour from wheat through comprehensive stages of grinding and separation. The primary energy is required to provide power used in grinding of wheat. In wheat milling, tempering is the process of adding water to wheat before milling to toughen the bran and mellow the endosperm. Gravity flow of the wheat is utilized to rotate the dampener wheel with cups to add water. Low cost gravity flow operated small electricity generator retrofit kit for dampener was designed and developed to justify low cost energy production without expensive solutions. Results of statistical analysis indicated that there was significant difference in mean values for voltage, rpm and flow rate at the 95% probability level. The resulted maximum mechanical power and measured electrical power were 5.1 W and 4.9 W respectively at wheat flow rate of 1.6 Kg/s and dampener wheel rotational velocity of 4.4 rad/s.

Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants

PubMed Central

Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

2014-01-01

Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier–Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. PMID:24664988

Droplet trapping and fast acoustic release in a multi-height device with steady-state flow.

PubMed

Rambach, Richard W; Linder, Kevin; Heymann, Michael; Franke, Thomas

2017-10-11

We demonstrate a novel multilayer polydimethylsiloxane (PDMS) device for selective storage and release of single emulsion droplets. Drops are captured in a microchannel cavity and can be released on-demand through a triggered surface acoustic wave pulse. The surface acoustic wave (SAW) is excited by a tapered interdigital transducer (TIDT) deposited on a piezoelectric lithium niobate (LiNbO 3 ) substrate and inverts the pressure difference across the cavity trap to push a drop out of the trap and back into the main flow channel. Droplet capture and release does not require a flow rate change, flow interruption, flow inversion or valve action and can be achieved in as fast as 20 ms. This allows both on-demand droplet capture for analysis and monitoring over arbitrary time scales, and continuous device operation with a high droplet rate of 620 drops per s. We hence decouple long-term droplet interrogation from other operations on the chip. This will ease integration with other microfluidic droplet operations and functional components.

Spacelab uplink/downlink data flow and formats

NASA Technical Reports Server (NTRS)

Kandefer, F.

1978-01-01

The results of an analysis of the Spacelab (SL) data uplink/downlink structure and those data system elements associated with the support of this data flow are presented. Specific objectives of this report are to present the results of the following analyses: (1) operations of the SL high rate multiplexer, including format structure, data rates, format combinations, format switching, etc.; (2) operations of SL data recorders to include the definition of modes, data rates and forms; (3) operations of the high rate demultiplexer as described above; (4) potential experiment data formats defining formatting parameters to be considered in decommutation analysis; (5) SL computer input/output (I/O) decommutation channels, including the definition of structure, quantity and use of this I/O data; (6) detailed requirements of the data quality monitoring philosophy for this function.

Task 4 supporting technology. Densification requirements definition and test objectives. Propellant densification requirements definition

NASA Technical Reports Server (NTRS)

Lak, Tibor; Weeks, D. P.

1995-01-01

The primary challenge of the X-33 CAN is to build and test a prototype LO2 and LH2 densification ground support equipment (GSE) unit, and perform tank thermodynamic testing within the 15 month phase 1 period. The LO2 and LH2 propellant densification system will be scaled for the IPTD LO2 and LH2 tank configurations. The IPTD tanks were selected for the propellant technology demonstration because of the potential benefits to the phase 1 plan: tanks will be built in time to support thermodynamic testing; minimum cost; minimum schedule risk; future testing at MSFC will build on phase 1 data base; and densification system will be available to support X-33 and RLV engine test at IPTD. The objective of the task 1 effort is to define the preliminary requirements of the propellant densification GSE and tank recirculation system. The key densification system design parameters to be established in Task 1 are: recirculation flow rate; heat exchanger inlet temperature; heat exchanger outlet temperature; maximum heat rejection rate; vent flow rate (GN2 and GH2); densification time; and tank pressure level.

An evaluation of the relations between flow regime components, stream characteristics, species traits and meta-demographic rates of warmwater stream fishes: Implications for aquatic resource management

USGS Publications Warehouse

Peterson, James T.; Shea, C.P.

2015-01-01

Fishery biologists are increasingly recognizing the importance of considering the dynamic nature of streams when developing streamflow policies. Such approaches require information on how flow regimes influence the physical environment and how those factors, in turn, affect species-specific demographic rates. A more cost-effective alternative could be the use of dynamic occupancy models to predict how species are likely to respond to changes in flow. To appraise the efficacy of this approach, we evaluated relative support for hypothesized effects of seasonal streamflow components, stream channel characteristics, and fish species traits on local extinction, colonization, and recruitment (meta-demographic rates) of stream fishes. We used 4 years of seasonal fish collection data from 23 streams to fit multistate, multiseason occupancy models for 42 fish species in the lower Flint River Basin, Georgia. Modelling results suggested that meta-demographic rates were influenced by streamflows, particularly short-term (10-day) flows. Flow effects on meta-demographic rates also varied with stream size, channel morphology, and fish species traits. Small-bodied species with generalized life-history characteristics were more resilient to flow variability than large-bodied species with specialized life-history characteristics. Using this approach, we simplified the modelling framework, thereby facilitating the development of dynamic, spatially explicit evaluations of the ecological consequences of water resource development activities over broad geographic areas. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

DESIGN ANALYSIS OF RADIAL INFLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

Gas Flow Detection System

NASA Technical Reports Server (NTRS)

Moss, Thomas; Ihlefeld, Curtis; Slack, Barry

2010-01-01

This system provides a portable means to detect gas flow through a thin-walled tube without breaking into the tubing system. The flow detection system was specifically designed to detect flow through two parallel branches of a manifold with only one inlet and outlet, and is a means for verifying a space shuttle program requirement that saves time and reduces the risk of flight hardware damage compared to the current means of requirement verification. The prototype Purge Vent and Drain Window Cavity Conditioning System (PVD WCCS) Flow Detection System consists of a heater and a temperature-sensing thermistor attached to a piece of Velcro to be attached to each branch of a WCCS manifold for the duration of the requirement verification test. The heaters and thermistors are connected to a shielded cable and then to an electronics enclosure, which contains the power supplies, relays, and circuit board to provide power, signal conditioning, and control. The electronics enclosure is then connected to a commercial data acquisition box to provide analog to digital conversion as well as digital control. This data acquisition box is then connected to a commercial laptop running a custom application created using National Instruments LabVIEW. The operation of the PVD WCCS Flow Detection System consists of first attaching a heater/thermistor assembly to each of the two branches of one manifold while there is no flow through the manifold. Next, the software application running on the laptop is used to turn on the heaters and to monitor the manifold branch temperatures. When the system has reached thermal equilibrium, the software application s graphical user interface (GUI) will indicate that the branch temperatures are stable. The operator can then physically open the flow control valve to initiate the test flow of gaseous nitrogen (GN2) through the manifold. Next, the software user interface will be monitored for stable temperature indications when the system is again at thermal equilibrium with the test flow of GN2. The temperature drop of each branch from its "no flow" stable temperature peak to its stable "with flow" temperature will allow the operator to determine whether a minimum level of flow exists. An alternative operation has the operator turning on the software only long enough to record the ambient temperature of the tubing before turning on the heaters and initiating GN2 flow. The stable temperature of the heated tubing with GN2 flow is then compared with the ambient tubing temperature to determine if flow is present in each branch. To help quantify the level of flow in the manifolds, each branch will be bench calibrated to establish its thermal properties using the flow detection system and different flow rates. These calibration values can then be incorporated into the software application to provide more detailed flow rate information.

Two stage turbine for rockets

NASA Technical Reports Server (NTRS)

Veres, Joseph P.

1993-01-01

The aerodynamic design and rig test evaluation of a small counter-rotating turbine system is described. The advanced turbine airfoils were designed and tested by Pratt & Whitney. The technology represented by this turbine is being developed for a turbopump to be used in an advanced upper stage rocket engine. The advanced engine will use a hydrogen expander cycle and achieve high performance through efficient combustion of hydrogen/oxygen propellants, high combustion pressure, and high area ratio exhaust nozzle expansion. Engine performance goals require that the turbopump drive turbines achieve high efficiency at low gas flow rates. The low mass flow rates and high operating pressures result in very small airfoil heights and diameters. The high efficiency and small size requirements present a challenging turbine design problem. The shrouded axial turbine blades are 50 percent reaction with a maximum thickness to chord ratio near 1. At 6 deg from the tangential direction, the nozzle and blade exit flow angles are well below the traditional design minimum limits. The blade turning angle of 160 deg also exceeds the maximum limits used in traditional turbine designs.

40 CFR 270.24 - Specific part B information requirements for process vents.

Code of Federal Regulations, 2011 CFR

2011-07-01

... emission reductions must be made using operating parameter values (e.g., temperatures, flow rates, or..., schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI Course 415...

40 CFR 270.24 - Specific part B information requirements for process vents.

Code of Federal Regulations, 2013 CFR

2013-07-01

... emission reductions must be made using operating parameter values (e.g., temperatures, flow rates, or..., schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI Course 415...

40 CFR 270.24 - Specific part B information requirements for process vents.

Code of Federal Regulations, 2012 CFR

2012-07-01

... emission reductions must be made using operating parameter values (e.g., temperatures, flow rates, or..., schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI Course 415...

40 CFR 270.24 - Specific part B information requirements for process vents.

Code of Federal Regulations, 2014 CFR

2014-07-01

... emission reductions must be made using operating parameter values (e.g., temperatures, flow rates, or..., schematics, and piping and instrumentation diagrams based on the appropriate sections of “APTI Course 415...

Velocity profile survey in a 16-in. custody-transfer orifice meter for natural gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, J.J.S.

1991-02-01

This paper describes a research project conducted at Chevron U.S.A. Inc.'s Venice, LA, facility to ascertain that the flow condition inside a nominal 16-in. (406-mm) custody-transfer orifice meter was in compliance with American Gas Assn. (AGA) requirements. The survey was conducted at four flow rates ranging from 160 to 200 MMscf/D (4.53 {times} 10{sup 6} to 5.66 {times} 10{sup 6} std m{sup 3}/d) of processed natural gas at 880 psia (6.1 MPa). Experimental data were collected by a portable data-acquisition system driven by a lap-top microcomputer. The measured profiles indicated that the flow was nearly fully developed at the orificemore » plate location, and no significant swirling motion was detected. This test successfully demonstrated the techniques and equipment developed for determining actual flow distributions inside orifice meters in the field under normal operating conditions. This technology can be used to detect detrimental flow profiles and to verify compliance with AGA requirements on flow conditions in custody-transfer orifice meters.« less

Calibration and use of filter test facility orifice plates

NASA Astrophysics Data System (ADS)

Fain, D. E.; Selby, T. W.

1984-07-01

There are three official DOE filter test facilities. These test facilities are used by the DOE, and others, to test nuclear grade HEPA filters to provide Quality Assurance that the filters meet the required specifications. The filters are tested for both filter efficiency and pressure drop. In the test equipment, standard orifice plates are used to set the specified flow rates for the tests. There has existed a need to calibrate the orifice plates from the three facilities with a common calibration source to assure that the facilities have comparable tests. A project has been undertaken to calibrate these orifice plates. In addition to reporting the results of the calibrations of the orifice plates, the means for using the calibration results will be discussed. A comparison of the orifice discharge coefficients for the orifice plates used at the seven facilities will be given. The pros and cons for the use of mass flow or volume flow rates for testing will be discussed. It is recommended that volume flow rates be used as a more practical and comparable means of testing filters. The rationale for this recommendation will be discussed.

Development of the US3D Code for Advanced Compressible and Reacting Flow Simulations

NASA Technical Reports Server (NTRS)

Candler, Graham V.; Johnson, Heath B.; Nompelis, Ioannis; Subbareddy, Pramod K.; Drayna, Travis W.; Gidzak, Vladimyr; Barnhardt, Michael D.

2015-01-01

Aerothermodynamics and hypersonic flows involve complex multi-disciplinary physics, including finite-rate gas-phase kinetics, finite-rate internal energy relaxation, gas-surface interactions with finite-rate oxidation and sublimation, transition to turbulence, large-scale unsteadiness, shock-boundary layer interactions, fluid-structure interactions, and thermal protection system ablation and thermal response. Many of the flows have a large range of length and time scales, requiring large computational grids, implicit time integration, and large solution run times. The University of Minnesota NASA US3D code was designed for the simulation of these complex, highly-coupled flows. It has many of the features of the well-established DPLR code, but uses unstructured grids and has many advanced numerical capabilities and physical models for multi-physics problems. The main capabilities of the code are described, the physical modeling approaches are discussed, the different types of numerical flux functions and time integration approaches are outlined, and the parallelization strategy is overviewed. Comparisons between US3D and the NASA DPLR code are presented, and several advanced simulations are presented to illustrate some of novel features of the code.

An improved design method and experimental performance of two dimensional curved wall diffusers

NASA Technical Reports Server (NTRS)

Yang, T.; Hudson, W. G.; El-Nashar, A. M.

1972-01-01

A computer design program was developed to incorporate the suction slots in solving the potential flow equations with prescribed boundary conditions. Using the contour generated from this program two Griffith diffusers were tested having area ratios AR = 3 and 4. The inlet Reynolds number ranged from 600,000 to 7 million. It was found that the slot suction required for metastable operation depends on the sidewall suction applied. Values of slot suction of 8% of the inlet flow rate was required for AR = 4 with metastable condition, provided that enough sidewall suction was applied. For AR = 3, the values of slot suction was about 25% lower than those required for AR = 4. For nearly all unseparated test runs, the effectiveness was 100% and the exit flow was uniform. In addition to the Griffith diffusers, dump and cusp diffusers of comparable area ratios were built and tested. The results obtained from these diffusers were compared with those of the Griffith diffusers. Flow separation occurred in all test runs with the dump and cusp diffusers.

Photogrammetric Measurement of Recession Rates of Low Temperature Ablators Subjected to High Speed Flow

DTIC Science & Technology

2011-06-01

recession rate prediction of carbon based, camphor and dry ice at hypersonic velocities...paradichlorobenzene, naphthalene, camphor , and ammonium chloride (Kohlman & Richardson, 1969). Except for dry ice, these materials require stagnation temperatures... Camphor , for example, sublimates at ~170C. With the reestablished interest in expendable ablative heat shields, these past experiences have

40 CFR 60.646 - Monitoring of emissions and operations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour... require a more frequent sampling schedule. (3) The average acid gas flow rate from the sweetening unit... rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24...

40 CFR 60.646 - Monitoring of emissions and operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour... require a more frequent sampling schedule. (3) The average acid gas flow rate from the sweetening unit... rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24...

40 CFR 60.646 - Monitoring of emissions and operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour... require a more frequent sampling schedule. (3) The average acid gas flow rate from the sweetening unit... rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24...

40 CFR 60.646 - Monitoring of emissions and operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour... require a more frequent sampling schedule. (3) The average acid gas flow rate from the sweetening unit... rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24...

40 CFR 60.646 - Monitoring of emissions and operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour... require a more frequent sampling schedule. (3) The average acid gas flow rate from the sweetening unit... rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24...

Calculating e-flow using UAV and ground monitoring

NASA Astrophysics Data System (ADS)

Zhao, C. S.; Zhang, C. B.; Yang, S. T.; Liu, C. M.; Xiang, H.; Sun, Y.; Yang, Z. Y.; Zhang, Y.; Yu, X. Y.; Shao, N. F.; Yu, Q.

2017-09-01

Intense human activity has led to serious degradation of basin water ecosystems and severe reduction in the river flow available for aquatic biota. As an important water ecosystem index, environmental flows (e-flows) are crucial for maintaining sustainability. However, most e-flow measurement methods involve long cycles, low efficiency, and transdisciplinary expertise. This makes it impossible to rapidly assess river e-flows at basin or larger scales. This study presents a new method to rapidly assessing e-flows coupling UAV and ground monitorings. UAV was firstly used to calculate river-course cross-sections with high-resolution stereoscopic images. A dominance index was then used to identify key fish species. Afterwards a habitat suitability index, along with biodiversity and integrity indices, was used to determine an appropriate flow velocity with full consideration of the fish spawning period. The cross-sections and flow velocity values were then combined into AEHRA, an e-flow assessment method for studying e-flows and supplying-rate. To verify the results from this new method, the widely used Tennant method was employed. The root-mean-square errors of river cross-sections determined by UAV are less than 0.25 m, which constitutes 3-5% water-depth of the river cross-sections. In the study area of Jinan city, the ecological flow velocity (VE) is equal to or greater than 0.11 m/s, and the ecological water depth (HE) is greater than 0.8 m. The river ecosystem is healthy with the minimum e-flow requirements being always met when it is close to large rivers, which is beneficial for the sustainable development of the water ecosystem. In the south river channel of Jinan, the upstream flow mostly meets the minimum e-flow requirements, and the downstream flow always meets the minimum e-flow requirements. The north of Jinan consists predominantly of artificial river channels used for irrigation. Rainfall rarely meets the minimum e-flow and irrigation water requirements. We suggest that the water shortage problem can be partly solved by diversion of the Yellow River. These results can provide useful information for ecological operations and restoration. The method used in this study for calculating e-flow based on a combination of UAV and ground monitoring can effectively promote research progress into basin e-flow, and provide an important reference for e-flow monitoring around the world.

Preliminary control system design and analysis for the Space Station Furnace Facility thermal control system

NASA Technical Reports Server (NTRS)

Jackson, M. E.

1995-01-01

This report presents the Space Station Furnace Facility (SSFF) thermal control system (TCS) preliminary control system design and analysis. The SSFF provides the necessary core systems to operate various materials processing furnaces. The TCS is defined as one of the core systems, and its function is to collect excess heat from furnaces and to provide precise cold temperature control of components and of certain furnace zones. Physical interconnection of parallel thermal control subsystems through a common pump implies the description of the TCS by coupled nonlinear differential equations in pressure and flow. This report formulates the system equations and develops the controllers that cause the interconnected subsystems to satisfy flow rate tracking requirements. Extensive digital simulation results are presented to show the flow rate tracking performance.

Sinks for photosynthetic electron flow in green petioles and pedicels of Zantedeschia aethiopica: evidence for innately high photorespiration and cyclic electron flow rates.

PubMed

Yiotis, Charilaos; Manetas, Yiannis

2010-07-01

A combination of gas exchange and various chlorophyll fluorescence measurements under varying O(2) and CO(2) partial pressures were used to characterize photosynthesis in green, stomata-bearing petioles of Zantedeschia aethiopica (calla lily) while corresponding leaves served as controls. Compared to leaves, petioles displayed considerably lower CO(2) assimilation rates, limited by both stomatal and mesophyll components. Further analysis of mesophyll limitations indicated lower carboxylating efficiencies and insufficient RuBP regeneration but almost similar rates of linear electron transport. Accordingly, higher oxygenation/carboxylation ratios were assumed for petioles and confirmed by experiments under non-photorespiratory conditions. Higher photorespiration rates in petioles were accompanied by higher cyclic electron flow around PSI, the latter being possibly linked to limitations in electron transport from intermediate electron carriers to end acceptors and low contents of PSI. Based on chlorophyll fluorescence methods, similar conclusions can be drawn for green pedicels, although gas exchange in these organs could not be applied due to their bulky size. Since our test plants were not subjected to stress we argue that higher photorespiration and cyclic electron flow rates are innate attributes of photosynthesis in stalks of calla lily. Active nitrogen metabolism may be inferred, while increased cyclic electron flow may provide the additional ATP required for the enhanced photorespiratory activity in petiole and pedicel chloroplasts and/or the decarboxylation of malate ascending from roots.

Applicability of empirical data currently used in predicting solid propellant exhaust plumes

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.; Greenwood, T.; Roberts, B. B.

1977-01-01

Theoretical and experimental approaches to exhaust plume analysis are compared. A two-phase model is extended to include treatment of reacting gas chemistry, and thermodynamical modeling of the gaseous phase of the flow field is considered. The applicability of empirical data currently available to define particle drag coefficients, heat transfer coefficients, mean particle size, and particle size distributions is investigated. Experimental and analytical comparisons are presented for subscale solid rocket motors operating at three altitudes with attention to pitot total pressure and stagnation point heating rate measurements. The mathematical treatment input requirements are explained. The two-phase flow field solution adequately predicts gasdynamic properties in the inviscid portion of two-phase exhaust plumes. It is found that prediction of exhaust plume gas pressures requires an adequate model of flow field dynamics.

Cooling rates for glass containing lunar compositions

NASA Technical Reports Server (NTRS)

Fang, C. Y.; Yinnon, H.; Uhlmann, D. R.

1983-01-01

Cooling rates required to form glassy or partly-crystalline bodies of 14 lunar compositions have been estimated using a previously introduced, simplified model. The calculated cooling rates are found to be in good agreement with cooling rates measured for the same compositions. Measurements are also reported of the liquidus temperature and glass transition temperature for each composition. Inferred cooling rates are combined with heat flow analyses to obtain insight into the thermal histories of samples 15422, 14162, 15025, 74220, 74241, 10084, 15425, and 15427. The critical cooling rates required to form glasses of 24 lunar compositions, including the 14 compositions of the present study, are suggested to increase systematically with increasing ratio of total network modifiers/total network formers in the compositions. This reflects the importance of melt viscosity in affecting glass formation.

Quantifying water requirements of riparian river red gum (Eucalyptus camaldulensis) in the Murray-Darling Basin, Australia: Implications for the management of environmental flows

USGS Publications Warehouse

Doody, Tanya M.; Colloff, Matthew J.; Davies, Micah; Koul, Vijay; Benyon, Richard G.; Nagler, Pamela L.

2015-01-01

Water resource development and drought have altered river flow regimes, increasing average flood return intervals across floodplains in the Murray-Darling Basin, Australia, causing health declines in riparian river red gum (Eucalyptus camaldulensis) forests and woodlands. Environmental flow allocations helped to alleviate water stress during the recent Millennium Drought (1997–2010), however, quantification of the flood frequency required to support healthy E. camaldulensis communities is still needed. We quantified water requirements of E. camaldulensis for two years across a flood gradient (trees inundated at frequencies of 1:2, 1:5 and 1:10 years) at Yanga National Park, New South Wales to help inform management decision-making and design of environmental flows. Sap flow, evaporative losses and soil moisture measurements were used to determine transpiration, evapotranspiration and plant-available soil water before and after flooding. A formula was developed using plant-available soil water post-flooding and average annual rainfall, to estimate maintenance time of soil water reserves in each flood frequency zone. Results indicated that soil water reserves could sustain 1:2 and 1:5 trees for 15 months and six years, respectively. Trees regulated their transpiration rates, allowing them to persist within their flood frequency zone, and showed reduction in active sapwood area and transpiration rates when flood frequencies exceeded 1:2 years. A leaf area index of 0.5 was identified as a potential threshold indicator of severe drought stress. Our results suggest environmental water managers may have greater flexibility to adaptively manage floodplains in order to sustain E. camaldulensis forests and woodlands than has been appreciated hitherto.

Modelling the breakup of solid aggregates in turbulent flows

NASA Astrophysics Data System (ADS)

B?Bler, Matth?Us U.; Morbidelli, Massimo; Ba?Dyga, Jerzy

The breakup of solid aggregates suspended in a turbulent flow is considered. The aggregates are assumed to be small with respect to the Kolmogorov length scale and the flow is assumed to be homogeneous. Further, it is assumed that breakup is caused by hydrodynamic stresses acting on the aggregates, and breakup is therefore assumed to follow a first-order kinetic where KB(x) is the breakup rate function and x is the aggregate mass. To model KB(x), it is assumed that an aggregate breaks instantaneously when the surrounding flow is violent enough to create a hydrodynamic stress that exceeds a critical value required to break the aggregate. For aggregates smaller than the Kolmogorov length scale the hydrodynamic stress is determined by the viscosity and local energy dissipation rate whose fluctuations are highly intermittent. Hence, the first-order breakup kinetics are governed by the frequency with which the local energy dissipation rate exceeds a critical value (that corresponds to the critical stress). A multifractal model is adopted to describe the statistical properties of the local energy dissipation rate, and a power-law relation is used to relate the critical energy dissipation rate above which breakup occurs to the aggregate mass. The model leads to an expression for KB(x) that is zero below a limiting aggregate mass, and diverges for x . When simulating the breakup process, the former leads to an asymptotic mean aggregate size whose scaling with the mean energy dissipation rate differs by one third from the scaling expected in a non-fluctuating flow.

Internal-liquid-film-cooling Experiments with Air-stream Temperatures to 2000 Degrees F. in 2- and 4-inch-diameter Horizontal Tubes

NASA Technical Reports Server (NTRS)

Kinney, George R; Abramson, Andrew E; Sloop, John L

1952-01-01

Report presents the results of an investigation conducted to determine the effectiveness of liquid-cooling films on the inner surfaces of tubes containing flowing hot air. Experiments were made in 2- and 4-inch-diameter straight metal tubes with air flows at temperatures from 600 degrees to 2000 degrees F. and diameter Reynolds numbers from 2.2 to 14 x 10(5). The film coolant, water, was injected around the circumference at a single axial position on the tubes at flow rates from 0.02 to .24 pound per second per foot of tube circumference (0.8 to 12 percent of the air flow). Liquid-coolant films were established and maintained around and along the tube wall in concurrent flow with the hot air. The results indicated that, in order to film cool a given surface area with as little coolant flow as possible, it may be necessary to limit the flow of coolant introduced at a single axial position and to introduce it at several axial positions. The flow rate of inert coolant required to maintain liquid-film cooling over a given area of tube surface can be estimated when the gas-flow conditions are known by means of a generalized plot of the film-cooling data.

Modeling of Turbulent Swirling Flows

NASA Technical Reports Server (NTRS)

Shih, Tsan-Hsing; Zhu, Jiang; Liou, William; Chen, Kuo-Huey; Liu, Nan-Suey; Lumley, John L.

1997-01-01

Aircraft engine combustors generally involve turbulent swirling flows in order to enhance fuel-air mixing and flame stabilization. It has long been recognized that eddy viscosity turbulence models are unable to appropriately model swirling flows. Therefore, it has been suggested that, for the modeling of these flows, a second order closure scheme should be considered because of its ability in the modeling of rotational and curvature effects. However, this scheme will require solution of many complicated second moment transport equations (six Reynolds stresses plus other scalar fluxes and variances), which is a difficult task for any CFD implementations. Also, this scheme will require a large amount of computer resources for a general combustor swirling flow. This report is devoted to the development of a cubic Reynolds stress-strain model for turbulent swirling flows, and was inspired by the work of Launder's group at UMIST. Using this type of model, one only needs to solve two turbulence equations, one for the turbulent kinetic energy k and the other for the dissipation rate epsilon. The cubic model developed in this report is based on a general Reynolds stress-strain relationship. Two flows have been chosen for model evaluation. One is a fully developed rotating pipe flow, and the other is a more complex flow with swirl and recirculation.

Gravel Mobility in a High Sand Content Riverbed

NASA Astrophysics Data System (ADS)

Haschenburger, J. K.

2017-12-01

In sand-gravel channels, sand may modify gravel transport by changing conditions of entrainment and promoting longer displacements or gravel may inhibit sand transport if concentrated into distinct deposits, which restrict sand supply with consequences for migrating bedform size or form. This study reports on gravel mobility in the lower San Antonio River, Texas, where gravel content in the bed material ranges from about 1% to more than 20%. Sediment transport observations were collected at three U.S. Geological Survey gauging stations by deploying a Helley-Smith sampler with a 0.2 mm mesh bag from which transport rates and mobile grain sizes were determined. The flow rates sampled translate into an annual exceedance expectation from 0.2% to 98%. Gravel transport rates are generally two orders of magnitude smaller than the rates of sand transport. However, the finest gravels are transported at rates on the same order of magnitude as the coarsest sands. At all sites, the 2 and 2.8 mm fractions are transported at the lowest flow rate sampled, suggesting mobility for at least 38% to as much as 98% of the year. Fractions as large as 8 mm are mobilized at flow rates that are expected between 25% and 53% of the year. The largest fractions captured in the sampling (16 to 32 mm) require flows closer to bankfull conditions that occur no more than 0.8% of the year. Results document that some gravel sizes can be frequently transported in low gradient riverbeds with high sand content.

Geometric pumping in autophoretic channels.

PubMed

Michelin, Sébastien; Montenegro-Johnson, Thomas D; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric

2015-08-07

Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.

Evaluation of blood flow in human exercising muscle by diffuse correlation spectroscopy: a phantom model study

NASA Astrophysics Data System (ADS)

Nakabayashi, Mikie; Ono, Yumie; Ichinose, Masashi

2018-02-01

Diffuse correlation spectroscopy (DCS) has a potential to noninvasively and quantitatively measure the blood flow in the exercising muscle that could contribute to the fields of sports physiology and medicine. However, the blood flow index (BFI) measured from skin surface by DCS reflects hemodynamic signals from both superficial tissue and muscle layer. Thus, an appropriate calibration technology is required to quantify the absolute blood flow in the muscle layer. We therefore fabricated a realistic two-layer phantom model consisted of a static silicon layer imitating superficial tissue and a dynamic flow layer imitating the muscle blood flow and investigated the relationship between the simulated blood flow rate in the muscle layer and the BFI measured from the surface of the phantom. The absorption coefficient and the reduced scattering coefficient of the forearm were measured from 25 healthy young adults using a time-resolved nearinfrared spectroscopy. The depths of the superficial and muscle layers of forearm were also determined by ultrasound tomography images from 25 healthy young adults. The phantoms were fabricated to satisfy these optical coefficients and anatomical constraints. The simulated blood flow rate were set from 0 mL/ min to 68.7 mL/ min in ten steps, which is considered to cover a physiological range of mean blood flow of the forearm between per 100g of muscle tissue at rest to heavy dynamic handgrip exercise. We found a proportional relationship between the flow rates and BFIs with significant correlation coefficient of R = 0.986. Our results suggest that the absolute exercising muscle blood flow could be estimated by DCS with optimal calibration using phantom models.

The use of three-parameter rating table lookup programs, RDRAT and PARM3, in hydraulic flow models

USGS Publications Warehouse

Sanders, C.L.

1995-01-01

Subroutines RDRAT and PARM3 enable computer programs such as the BRANCH open-channel unsteady-flow model to route flows through or over combinations of critical-flow sections, culverts, bridges, road- overflow sections, fixed spillways, and(or) dams. The subroutines also obstruct upstream flow to simulate operation of flapper-type tide gates. A multiplier can be applied by date and time to simulate varying numbers of tide gates being open or alternative construction scenarios for multiple culverts. The subroutines use three-parameter (headwater, tailwater, and discharge) rating table lookup methods. These tables may be manually prepared using other programs that do step-backwater computations or compute flow through bridges and culverts or over dams. The subroutine, therefore, precludes the necessity of incorporating considerable hydraulic computational code into the client program, and provides complete flexibility for users of the model for routing flow through almost any affixed structure or combination of structures. The subroutines are written in Fortran 77 language, and have minimal exchange of information with the BRANCH model or other possible client programs. The report documents the interpolation methodology, data input requirements, and software.

A microfluidic fuel cell with flow-through porous electrodes.

PubMed

Kjeang, Erik; Michel, Raphaelle; Harrington, David A; Djilali, Ned; Sinton, David

2008-03-26

A microfluidic fuel cell architecture incorporating flow-through porous electrodes is demonstrated. The design is based on cross-flow of aqueous vanadium redox species through the electrodes into an orthogonally arranged co-laminar exit channel, where the waste solutions provide ionic charge transfer in a membraneless configuration. This flow-through architecture enables improved utilization of the three-dimensional active area inside the porous electrodes and provides enhanced rates of convective/diffusive transport without increasing the parasitic loss required to drive the flow. Prototype fuel cells are fabricated by rapid prototyping with total material cost estimated at 2 USD/unit. Improved performance as compared to previous microfluidic fuel cells is demonstrated, including power densities at room temperature up to 131 mW cm-2. In addition, high overall energy conversion efficiency is obtained through a combination of relatively high levels of fuel utilization and cell voltage. When operated at 1 microL min-1 flow rate, the fuel cell produced 20 mW cm-2 at 0.8 V combined with an active fuel utilization of 94%. Finally, we demonstrate in situ fuel and oxidant regeneration by running the flow-through architecture fuel cell in reverse.

The Role of Fine Sediment Content on Soil Consolidation and Debris Flows Development after Earthquake

NASA Astrophysics Data System (ADS)

Lyu, L.; Xu, M., III; Wang, Z.

2017-12-01

Fine sediment has been identified as an important factor determining the critical runoff that initiates debris flows because its contribution to shear strength through consolidation. Especially, owing to the 2008 Wenchuan earthquake in China enormous of loose sediment with different fractions of fine particles was eroded and supplied as materials for debris flows. The loose materials are gradually consolidated along with time, and therefore stronger rainfall is required to overcome the shear strength and to initiate debris flows. In this study, flume experiments were performed to explore soil consolidation and shear strength on mass failure and debris flow initiation under the conditions that different fractions of fine sediment were contained in the materials. Under the low content of fine sediment conditions (mass percentages: 0-10%), the debris flows formed with large pores and low shear strength and thus fine particles were too few to fill up the pores among the coarse particles. The consolidation rate was mostly influenced by the content of the fine particles. Consolidation of fine particles caused an increase of the shear strength and decrease of the rainfall infiltration, and therefore, debris flow initiation required stronger rainfall as the consolidation of the fine particles developed.

Using a reactive transport model to elucidate differences between laboratory and field dissolution rates in regolith

NASA Astrophysics Data System (ADS)

Moore, Joel; Lichtner, Peter C.; White, Art F.; Brantley, Susan L.

2012-09-01

The reactive transport model FLOTRAN was used to forward-model weathering profiles developed on granitic outwash alluvium over 40-3000 ka from the Merced, California (USA) chronosequence as well as deep granitic regolith developed over 800 ka near Davis Run, Virginia (USA). Baseline model predictions that used laboratory rate constants (km), measured fluid flow velocities (v), and BET volumetric surface areas for the parent material (AB,mo) were not consistent with measured profiles of plagioclase, potassium feldspar, and quartz. Reaction fronts predicted by the baseline model are deeper and thinner than the observed, consistent with faster rates of reaction in the model. Reaction front depth in the model depended mostly upon saturated versus unsaturated hydrologic flow conditions, rate constants controlling precipitation of secondary minerals, and the average fluid flow velocity (va). Unsaturated hydrologic flow conditions (relatively open with respect to CO2(g)) resulted in the prediction of deeper reaction fronts and significant differences in the separation between plagioclase and potassium feldspar reaction fronts compared to saturated hydrologic flow (relatively closed with respect to CO2(g)). Under saturated or unsaturated flow conditions, the rate constant that controls precipitation rates of secondary minerals must be reduced relative to laboratory rate constants to match observed reaction front depths and measured pore water chemistry. Additionally, to match the observed reaction front depths, va was set lower than the measured value, v, for three of the four profiles. The reaction front gradients in mineralogy and pore fluid chemistry could only be modeled accurately by adjusting values of the product kmAB,mo. By assuming km values were constrained by laboratory data, field observations were modeled successfully with TST-like rate equations by dividing measured values of AB,mo by factors from 50 to 1700. Alternately, with sigmoidal or Al-inhibition rate models, this adjustment factor ranges from 5 to 170. Best-fit models of the wetter, hydrologically saturated Davis Run profile required a smaller adjustment to AB,mo than the drier hydrologically unsaturated Merced profiles. We attributed the need for large adjustments in va and AB,mo necessary for the Merced models to more complex hydrologic flow that decreased the reactive surface area in contact with bulk flow water, e.g., dead-end pore spaces containing fluids that are near or at chemical equilibrium. Thus, rate models from the laboratory can successfully predict weathering over millions of years, but work is needed to understand how to incorporate changes in what controls the relationship between reactive surface area and hydrologic flow.

Spiromax, a New Dry Powder Inhaler: Dose Consistency under Simulated Real-World Conditions

PubMed Central

Canonica, Giorgio Walter; Arp, Jan; Keegstra, Johan René

2015-01-01

Abstract Background: Spiromax® is a novel dry powder inhaler for patients with asthma or chronic obstructive pulmonary disease (COPD). The studies presented here provide further data on attributes (in vitro dosing consistency with budesonide–formoterol (DuoResp) Spiromax; flow rates through empty versions of the Spiromax and Turbuhaler inhaler) of importance to patients with asthma or COPD. Methods: Dose-delivery studies were performed using low-, middle-, and high-strength DuoResp Spiromax. Dose consistency was assessed over inhaler life. Total emitted doses (TEDs) were measured at various flow rates, after exposure to high and low temperature or humidity, at different inhaler orientations, and after dropping the inhaler. The criterion for evaluating dose uniformity was whether mean TEDs were within the product specification limits. In separate studies, flow rates were measured after training, using the patient information leaflets, and again after enhanced training as part of a randomized, open-label, cross-over study. Results: Mean values for both budesonide and formoterol were within 85%–115% of the label claim for each strength of DuoResp Spiromax for initial dose uniformity and for the other investigated conditions (temperature, humidity, orientation, dropping, knocking), with the exception of approximately an 80% increase in first dose after dropping the inhaler (subsequent doses not affected). In the flow rate patient study, two patients' inhalations with Spiromax and six with Turbuhaler were <30 L/min. The majority of asthma patients [91% (Spiromax) versus 82% (Turbuhaler)] achieved the preferred flow rate of >60 L/min. Conclusions: DuoResp Spiromax consistently meets dose uniformity criteria, under controlled laboratory conditions and with variations intended to mimic real-world use. Following enhanced training, all patients in the flow study were able to achieve the minimal inspiratory flow rate of >30 L/min, which is required for effective treatment. PMID:26352860

Self-regulated cooling flows in elliptical galaxies and in cluster cores - Is exclusively low mass star formation really necessary?

NASA Technical Reports Server (NTRS)

Silk, J.; Djorgovski, S.; Wyse, R. F. G.; Bruzual A., G.

1986-01-01

A self-consistent treatment of the heating by supernovae associated with star formation in a spherically symmetric cooling flow in a cluster core or elliptical galaxy is presented. An initial stellar mass function similar to that in the solar neighborhood is adopted. Inferred star-formation rates, within the cooling region - typically the inner 100 kpc around dominant galaxies at the centers of cooling flows in XD clusters - are reduced by about a factor of 2, relative to rates inferred when the heat input from star formation is ignored. Truncated initial mass functions (IMFs) are also considered, in which massive star formation is suppressed in accordance with previous treatments, and colors are predicted for star formation in cooling flows associated with central dominant elliptical galaxies and with isolated elliptical galaxies surrounded by gaseous coronae. The low inferred cooling-flow rates around isolated elliptical galaxies are found to be insensitive to the upper mass cutoff in the IMF, provided that the upper mass cutoff exceeds 2 M solar mass. Comparison with observed colors favors a cutoff in the IMF above 1 M solar mass in at least two well-studied cluster cooling flows, but a normal IMF cannot be excluded definitively. Models for NGC 1275 support a young (less than about 3 Gyr) cooling flow. As for the isolated elliptical galaxies, the spread in colors is consistent with a normal IMF. A definitive test of the IMF arising via star formation in cooling flows requires either UV spectral data or supernova searches in the cooling-flow-centered galaxies.

Regenerative Blower for EVA Suit Ventilation Fan

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Paul, Heather L.

2010-01-01

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at sub-atmospheric pressures that simulate a PLSS ventilation loop environment. Head/flow performance and maximum efficiency point data were used to specify the design and operating conditions for the ventilation fan. We identified materials for the blower that will enhance safety for operation in a lunar environment, and produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSE ventilation subsystem while running at 5400 rpm, consuming only 9 W of electric power using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power regenerative blower can meet the performance requirements for future space suit life support systems.

Erosion by an Alpine glacier.

PubMed

Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y Y; Avouac, Jean-Philippe; Cox, Simon C

2015-10-09

Assessing the impact of glaciation on Earth's surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years. Copyright © 2015, American Association for the Advancement of Science.

Minimum data requirement for neural networks based on power spectral density analysis.

PubMed

Deng, Jiamei; Maass, Bastian; Stobart, Richard

2012-04-01

One of the most critical challenges ahead for diesel engines is to identify new techniques for fuel economy improvement without compromising emissions regulations. One technique is the precise control of air/fuel ratio, which requires the measurement of instantaneous fuel consumption. Measurement accuracy and repeatability for fuel rate is the key to successfully controlling the air/fuel ratio and real-time measurement of fuel consumption. The volumetric and gravimetric measurement principles are well-known methods for measurement of fuel consumption in internal combustion engines. However, the fuel flow rate measured by these methods is not suitable for either real-time control or real-time measurement purposes because of the intermittent nature of the measurements. This paper describes a technique that can be used to find the minimum data [consisting of data from just 2.5% of the non-road transient cycle (NRTC)] to solve the problem concerning discontinuous data of fuel flow rate measured using an AVL 733S fuel meter for a medium or heavy-duty diesel engine using neural networks. Only torque and speed are used as the input parameters for the fuel flow rate prediction. Power density analysis is used to find the minimum amount of the data. The results show that the nonlinear autoregressive model with exogenous inputs could predict the particulate matter successfully with R(2) above 0.96 using 2.5% NRTC data with only torque and speed as inputs.

Flow adjustment inside large finite-size wind farms approaching the infinite wind farm regime

NASA Astrophysics Data System (ADS)

Wu, Ka Ling; Porté-Agel, Fernando

2017-04-01

Due to the increasing number and the growing size of wind farms, the distance among them continues to decrease. Thus, it is necessary to understand how these large finite-size wind farms and their wakes could interfere the atmospheric boundary layer (ABL) dynamics and adjacent wind farms. Fully-developed flow inside wind farms has been extensively studied through numerical simulations of infinite wind farms. The transportation of momentum and energy is only vertical and the advection of them is neglected in these infinite wind farms. However, less attention has been paid to examine the length of wind farms required to reach such asymptotic regime and the ABL dynamics in the leading and trailing edges of the large finite-size wind farms. Large eddy simulations are performed in this study to investigate the flow adjustment inside large finite-size wind farms in conventionally-neutral boundary layer with the effect of Coriolis force and free-atmosphere stratification from 1 to 5 K/km. For the large finite-size wind farms considered in the present work, when the potential temperature lapse rate is 5 K/km, the wind farms exceed the height of the ABL by two orders of magnitude for the incoming flow inside the farms to approach the fully-developed regime. An entrance fetch of approximately 40 times of the ABL height is also required for such flow adjustment. At the fully-developed flow regime of the large finite-size wind farms, the flow characteristics match those of infinite wind farms even though they have different adjustment length scales. The role of advection at the entrance and exit regions of the large finite-size wind farms is also examined. The interaction between the internal boundary layer developed above the large finite-size wind farms and the ABL under different potential temperature lapse rates are compared. It is shown that the potential temperature lapse rate plays a role in whether the flow inside the large finite-size wind farms adjusts to the fully-developed flow regime. The flow characteristics of the wake of these large finite-size wind farms are reported to forecast the effect of large finite-size wind farms on adjacent wind farms. A power deficit as large as 8% is found at a distance of 10 km downwind from the large finite-size wind farms.

Use of Numerical Models to Simulate Transport of Sewage-Derived Nitrate in a Coastal Aquifer, Central and Western Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.

2008-01-01

The unconsolidated glacial sediments underlying Cape Cod, Massachusetts compose a regional aquifer system that is used both as a source of drinking water and as a disposal site for wastewater; in addition, the discharge of clean ground water from the aquifer system is needed for the maintenance of freshwater and marine ecosystems throughout the region. Because these uses of the aquifer conflict with one another in many areas of the Cape, local and regional planners have begun to develop sustainable wastewater plans that will facilitate the disposal of wastewater while protecting water supplies and improving the health of aquatic ecosystems. To assist local and regional planners in these efforts, the U.S. Geological Survey conducted a 2-year investigation to (1) assist local and regional planners in the evaluation of potential wastewater scenarios, (2) use results and interpretation from these analyses to develop hydrologic concepts transferable throughout the region, and (3) establish and test methods that would be of use in future evaluations. Wastewater-disposal scenarios need to be evaluated in the context of the regional ground-water-flow system. For a given rate of disposal, wastewater from sites at or near a regional ground-water divide is transported in a wider arc of flow directions, flows deeper in the system, and contaminates a larger part of the aquifer than does wastewater discharged from sites farther from the divide. Also, traveltimes of wastewater from sites near a ground-water divide to receptors are longer (as much as several hundred years) than traveltimes from sites farther from the divide. Thus, wastewater disposal at or near a divide will affect a larger part of the aquifer and likely contribute wastewater to more receptors than wastewater disposal farther from a divide; however, longer traveltimes could allow for more attenuation of wastewater-derived nitrate from those sites. Ground-water-flow models and particle tracking can be used to identify advective-transport patterns downgradient from wastewater-disposal sites and estimate traveltimes; however, these tools cannot predict the distribution of mass or concentrations of wastewater constituents, such as nitrate, in the aquifer. Flow-based particle-tracking analyses can be used to estimate mass-loading rates and time-varying concentrations at wells and ecological receptors by the accounting of mass-weighted particles discharging into the receptor of interest. This method requires no additional development beyond the flow model; however, post-modeling analyses are required. In addition, the method is based on the assumption that no mass is lost during transport, an assumption that likely is not valid in many systems. Solute-transport models simulate the subsurface transport of nitrate through the aquifer and predict the distribution of the mass of a solute in the aquifer at different transport times. This method does require additional model development beyond the flow model, but can predict timevarying concentrations at receptors. Estimates of mass-loading rates require minimal post-modeling analyses. Time-varying concentrations and mass-loading rates calculated for wells in eastern Barnstable by the two methods generally were in reasonable agreement. Inherent in the flow-based particle-tracking method is the assumption that mass is conserved along a given flow line and that there is no spreading of mass in the aquifer. Although the solute-transport models also incorporate a system-wide conservation of mass, these models allow for a spreading of mass in the aquifer, and mass is not conserved along a given flow line. As a result, estimates of concentrations and mass loading rates generally were higher in particle-tracking analyses than in solute-transport simulations. Results from the two types of simulations agreed best for wells that receive large amounts of wastewater with short traveltimes (less than 10 years) because insufficient transport

New results in gravity dependent two-phase flow regime mapping

NASA Astrophysics Data System (ADS)

Kurwitz, Cable; Best, Frederick

2002-01-01

Accurate prediction of thermal-hydraulic parameters, such as the spatial gas/liquid orientation or flow regime, is required for implementation of two-phase systems. Although many flow regime transition models exist, accurate determination of both annular and slug regime boundaries is not well defined especially at lower flow rates. Furthermore, models typically indicate the regime as a sharp transition where data may indicate a transition space. Texas A&M has flown in excess of 35 flights aboard the NASA KC-135 aircraft with a unique two-phase package. These flights have produced a significant database of gravity dependent two-phase data including visual observations for flow regime identification. Two-phase flow tests conducted during recent zero-g flights have added to the flow regime database and are shown in this paper with comparisons to selected transition models. .

Gel compression considerations for chromatography scale-up for protein C purification.

PubMed

He, W; Bruley, D F; Drohan, W N

1998-01-01

This work is to establish theoretical and experimental relationships for the scale-up of Immobilized Metal Affinity Chromatography (IMAC) and Immuno Affinity Chromatography for the low cost production of large quantities of Protein C. The external customer requirements for this project have been established for Protein C deficient people with the goal of providing prophylactic patient treatment. Deep vein thrombosis is the major symptom for protein C deficiency creating the potential problem of embolism transport to important organs, such as, lung and brain. Gel matrices for protein C separation are being analyzed to determine the relationship between the material properties of the gel and the column collapse characteristics. The fluid flow rate and pressure drop is being examined to see how they influence column stability. Gel packing analysis includes two considerations; one is bulk compression due to flow rate, and the second is gel particle deformation due to fluid flow and pressure drop. Based on the assumption of creeping flow, Darcy's law is being applied to characterize the flow through the gel particles. Biot's mathematical description of three-dimensional consolidation in porous media is being used to develop a set of system equations. Finite difference methods are being utilized to obtain the equation solutions. In addition, special programs such as finite element approaches, ABAQUS, will be studied to determine their application to this particular problem. Experimental studies are being performed to determine flow rate and pressure drop correlation for the chromatographic columns with appropriate gels. Void fraction is being measured using pulse testing to allow Reynolds number calculations. Experimental yield stress is being measured to compare with the theoretical calculations. Total Quality Management (TQM) tools have been utilized to optimize this work. For instance, the "Scatter Diagram" has been used to evaluate and select the appropriate gels and operating conditions via Taguchi techniques. Targeting customer requirements under the structure of TQM represents a novel approach to graduate student research in an academic institution which is designed to simulate an industrial environment.

The Debye-Huckel Approximation in Electroosmotic Flow in Micro- and Nano-channels

NASA Astrophysics Data System (ADS)

Conlisk, A. Terrence

2002-11-01

In this work we consider the electroosmotic flow in a rectangular channel. We consider a mixture of water or other neutral solvent and a salt compound such as sodium chloride and other buffers for which the ionic species are entirely dissociated. Results are produced for the case where the channel height is much greater than the electric double layer(EDL)(microchannel) and for the case where the channel height is of the order or slightly greater than the width of the EDL(nanochannel). At small cation, anion concentration differences the Debye-Huckel approximation is appropriate; at larger concentration differences, the Gouy-Chapman picture of the electric double emerges naturally. In the symmetric case for the electroosmotic flow so induced, the velocity field and the potential are similar. We specifically focus in this paper on the limits of the Debye-Huckel approximation for a simplified version of a phosphate buffered saline(PBS) mixture. The fluid is assumed to behave as a continuum and the volume flow rate is observed to vary linearly with channel height for electrically driven flow in contrast to pressure driven flow which varies as height cubed. This means that very large pressure drops are required to drive flows in small channels. However, useful volume flow rates may be obtained at a very low driving voltage.

Lower crustal flow and the role of shear in basin subsidence: An example from the Dead Sea basin

USGS Publications Warehouse

Al-Zoubi, A.; ten Brink, Uri S.

2002-01-01

We interpret large-scale subsidence (5–6 km depth) with little attendant brittle deformation in the southern Dead Sea basin, a large pull-apart basin along the Dead Sea transform plate boundary, to indicate lower crustal thinning due to lower crustal flow. Along-axis flow within the lower crust could be induced by the reduction of overburden pressure in the central Dead Sea basin, where brittle extensional deformation is observed. Using a channel flow approximation, we estimate that lower crustal flow would occur within the time frame of basin subsidence if the viscosity is ≤7×1019–1×1021 Pa s, a value compatible with the normal heat flow in the region. Lower crustal viscosity due to the strain rate associated with basin extension is estimated to be similar to or smaller than the viscosity required for a channel flow. However, the viscosity under the basin may be reduced to 5×1017–5×1019 Pa s by the enhanced strain rate due to lateral shear along the transform plate boundary. Thus, lower crustal flow facilitated by shear may be a viable mechanism to enlarge basins and modify other topographic features even in the absence of underlying thermal anomalies.

40 CFR 63.526 - Monitoring requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... vent. (D) Design analysis based on accepted chemical engineering principles, measurable process.... (i) For the purpose of determining de minimis status for emission points, engineering assessment may... operating conditions expected to yield the highest flow rate and concentration. Engineering assessment...

40 CFR 63.526 - Monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... vent. (D) Design analysis based on accepted chemical engineering principles, measurable process.... (i) For the purpose of determining de minimis status for emission points, engineering assessment may... operating conditions expected to yield the highest flow rate and concentration. Engineering assessment...

40 CFR 63.526 - Monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... vent. (D) Design analysis based on accepted chemical engineering principles, measurable process.... (i) For the purpose of determining de minimis status for emission points, engineering assessment may... operating conditions expected to yield the highest flow rate and concentration. Engineering assessment...

40 CFR Table 2 to Subpart Cccc of... - Requirements for Performance Tests

Code of Federal Regulations, 2010 CFR

2010-07-01

... port's location and the number of traverse points Method 1* 3. Measure volumetric flow rate. Method 2* 4. Perform gas analysis to determine the dry molecular weight of the stack gas Method 3* 5...

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642 SSV... ranges of dilution air dewpoint versus calibration air dewpoint in Table 3 of § 1065.640, you may set M...

Computational study of duct and pipe flows using the method of pseudocompressibility

NASA Technical Reports Server (NTRS)

Williams, Robert W.

1991-01-01

A viscous, three-dimensional, incompressible, Navier-Stokes Computational Fluid Dynamics code employing pseudocompressibility is used for the prediction of laminar primary and secondary flows in two 90-degree bends of constant cross section. Under study are a square cross section duct bend with 2.3 radius ratio and a round cross section pipe bend with 2.8 radius ratio. Sensitivity of predicted primary and secondary flow to inlet boundary conditions, grid resolution, and code convergence is investigated. Contour and velocity versus spanwise coordinate plots comparing prediction to experimental data flow components are shown at several streamwise stations before, within, and after the duct and pipe bends. Discussion includes secondary flow physics, computational method, computational requirements, grid dependence, and convergence rates.

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

NASA Astrophysics Data System (ADS)

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.

Detecting Human Hydrologic Alteration from Diversion Hydropower Requires Universal Flow Prediction Tools: A Proposed Framework for Flow Prediction in Poorly-gauged, Regulated Rivers

NASA Astrophysics Data System (ADS)

Kibler, K. M.; Alipour, M.

2016-12-01

Achieving the universal energy access Sustainable Development Goal will require great investment in renewable energy infrastructure in the developing world. Much growth in the renewable sector will come from new hydropower projects, including small and diversion hydropower in remote and mountainous regions. Yet, human impacts to hydrological systems from diversion hydropower are poorly described. Diversion hydropower is often implemented in ungauged rivers, thus detection of impact requires flow analysis tools suited to prediction in poorly-gauged and human-altered catchments. We conduct a comprehensive analysis of hydrologic alteration in 32 rivers developed with diversion hydropower in southwestern China. As flow data are sparse, we devise an approach for estimating streamflow during pre- and post-development periods, drawing upon a decade of research into prediction in ungauged basins. We apply a rainfall-runoff model, parameterized and forced exclusively with global-scale data, in hydrologically-similar gauged and ungauged catchments. Uncertain "soft" data are incorporated through fuzzy numbers and confidence-based weighting, and a multi-criteria objective function is applied to evaluate model performance. Testing indicates that the proposed framework returns superior performance (NSE = 0.77) as compared to models parameterized by rote calibration (NSE = 0.62). Confident that the models are providing `the right answer for the right reasons', our analysis of hydrologic alteration based on simulated flows indicates statistically significant hydrologic effects of diversion hydropower across many rivers. Mean annual flows, 7-day minimum and 7-day maximum flows decreased. Frequency and duration of flow exceeding Q25 decreased while duration of flows sustained below the Q75 increased substantially. Hydrograph rise and fall rates and flow constancy increased. The proposed methodology may be applied to improve diversion hydropower design in data-limited regions.

Flow injection method for sulphide determination using an organic mercury compound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaqoob, M.; Anwar, M.; Masood, A.S.

1991-04-01

A simple flow injection analysis method is described for the determination of soluble sulfide, based on the complexation of sulfide with p-hydroxymercurbenzoic acid, in the presence of dithizone used as an indicator. The reaction is very rapid, with a sampling rate of 90/hr. and requires a very short length post injection reaction coil. The detection limit and precision are 0.01 mM and 0.7%, respectively.

Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics.

PubMed

Cebral, J R; Mut, F; Chung, B J; Spelle, L; Moret, J; van Nijnatten, F; Ruijters, D

2017-06-01

Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms. DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms. The average similarity between the DSA and the projected computational fluid dynamics flow fields was 78% in the parent artery, while it was only 30% in the aneurysm region. Qualitatively, both the DSA and projected computational fluid dynamics flow fields captured the location of the inflow jet, the main vortex structure, the intrasaccular flow split, and the main rotation direction in approximately 60% of the cases. Several factors affect the reconstruction of 2D flow fields from dynamic angiography sequences. The most important factors are the 3-dimensionality of the intrasaccular flow patterns and inflow jets, the alignment of the main vortex structure with the line of sight, the overlapping of surrounding vessels, and possibly frame rate undersampling. Flow visualization with DSA from >1 projection is required for understanding of the 3D intrasaccular flow patterns. Although these DSA-based flow quantification techniques do not capture swirling or secondary flows in the parent artery, they still provide a good representation of the mean axial flow and the corresponding flow rate. © 2017 by American Journal of Neuroradiology.

Flux Recovery of a Forward Osmosis Membrane After a Fouling Process

NASA Technical Reports Server (NTRS)

Gamboa-Vázquez, Sonia; Flynn, Michael; Romero Mangado, Jaione; Parodi, Jurek

2016-01-01

Wastewater treatment through Forward Osmosis (FO) membranes is a process that has been evaluated in the past years as an innovative technology for the Next Generation Life Support Systems. FO technologies are cost effective, and require very low energy consumption, but are subject to membrane fouling. Membrane fouling occurs when unwanted materials accumulate on the active side of the membrane during the wastewater treatment process, which leads to a decrease in membrane flow rates. Membrane fouling can be reversed with the use of antifoulant solutions. The aim of this study is to identify the materials that cause flow rate reduction due to membrane fouling, as well as to evaluate the flux recovery after membrane treatment using commercially available antifoulants. 3D Laser Scanning Microscope images were taken to observe the surface of the membrane. Fourier Transform Infrared (FTIR) spectrometry results identified possible compounds that cause membrane fouling and FO testing results demonstrated flow rate recovery after membrane treatment using antifoulants.

Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

NASA Astrophysics Data System (ADS)

Beyerlein, K. R.; Adriano, L.; Heymann, M.; Kirian, R.; Knoška, J.; Wilde, F.; Chapman, H. N.; Bajt, S.

2015-12-01

Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injection molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquid flow conservation. Finally, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.

Determining Near-Bottom Fluxes of Passive Tracers in Aquatic Environments

NASA Astrophysics Data System (ADS)

Bluteau, Cynthia E.; Ivey, Gregory N.; Donis, Daphne; McGinnis, Daniel F.

2018-03-01

In aquatic systems, the eddy correlation method (ECM) provides vertical flux measurements near the sediment-water interface. The ECM independently measures the turbulent vertical velocities w' and the turbulent tracer concentration c' at a high sampling rate (> 1 Hz) to obtain the vertical flux w'c'¯ from their time-averaged covariance. This method requires identifying and resolving all the flow-dependent time (and length) scales contributing to w'c'¯. With increasingly energetic flows, we demonstrate that the ECM's current technology precludes resolving the smallest flux-contributing scales. To avoid these difficulties, we show that for passive tracers such as dissolved oxygen, w'c'¯ can be measured from estimates of two scalar quantities: the rate of turbulent kinetic energy dissipation ɛ and the rate of tracer variance dissipation χc. Applying this approach to both laboratory and field observations demonstrates that w'c'¯ is well resolved by the new method and can provide flux estimates in more energetic flows where the ECM cannot be used.

Experiences with explicit finite-difference schemes for complex fluid dynamics problems on STAR-100 and CYBER-203 computers

NASA Technical Reports Server (NTRS)

Kumar, A.; Rudy, D. H.; Drummond, J. P.; Harris, J. E.

1982-01-01

Several two- and three-dimensional external and internal flow problems solved on the STAR-100 and CYBER-203 vector processing computers are described. The flow field was described by the full Navier-Stokes equations which were then solved by explicit finite-difference algorithms. Problem results and computer system requirements are presented. Program organization and data base structure for three-dimensional computer codes which will eliminate or improve on page faulting, are discussed. Storage requirements for three-dimensional codes are reduced by calculating transformation metric data in each step. As a result, in-core grid points were increased in number by 50% to 150,000, with a 10% execution time increase. An assessment of current and future machine requirements shows that even on the CYBER-205 computer only a few problems can be solved realistically. Estimates reveal that the present situation is more storage limited than compute rate limited, but advancements in both storage and speed are essential to realistically calculate three-dimensional flow.

A direct-interface fusible heat sink for astronaut cooling

NASA Technical Reports Server (NTRS)

Lomax, Curtis; Webbon, B. W.

1990-01-01

Astronaut cooling during extravehicular activity is a critical design issue in developing a portable life support system that meets the requirements of a space station mission. Some the requirements are that the cooling device can be easily regenerable and nonventing during operation. In response to this, a direct-interface, fusible heat sink prototpye with freezable quick-disconnects was developed. A proof-of-concept prototype was constructed and tested that consists of an elastic container filled with normal tap water and having two quick-disconnects embedded in a wall. These quick-disconnects are designed so that they may be frozen with the ice and yet still be joined to the cooling system, allowing an immediate flow path. The inherent difficulties in a direct-interface heat sink have been overcome, i.e., (1) establishing an initial flow path; (2) avoiding low-flow freeze-up; and (3) achieving adequate heat-transfer rates at the end of the melting process. The requirements, design, fabrication, and testing are discussed.

A direct-interface, fusible heat sink for astronaut cooling

NASA Technical Reports Server (NTRS)

Lomax, Curtis; Webbon, B. W.

1990-01-01

Astronaut cooling during extravehicular activity is a critical design issue in developing a portable life support system that meets the requirements of a space station mission. Some of the requirements are that the cooling device can be easily regenerable and nonventing during operation. In response to this, a direct-interface, fusible heat sink prototype with freezable quick-disconnects was developed. A proof-of-concept prototype was constructed and tested that consists of an elastic container filled with normal tap water and having two quick-disconnects embedded in a wall. These quick-disconnects are designed so that they may be frozen with the ice and yet still be joined to the cooling system, allowing an immediate flow path. The inherent difficulties in a direct-interface heat sink have been overcome, i.e., (1) establishing an initial flow path; (2) avoiding low-flow freeze-up; and (3) achieving adequate heat-transfer rates at the end of the melting process. The requirements, design, fabrication, and testing are discussed.

Particulate generation and control in the PREPP (Process Experimental Pilot Plant) incinerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stermer, D.L.; Gale, L.G.

1989-03-01

Particulate emissions in radioactive incineration systems using a wet scrubbing system are generally ultimately controlled by flowing the process offgas stream through a high-efficiency filter, such as a High Efficient Particulate Air (HEPA) filter. Because HEPA filters are capable of reducing particulate emissions over an order of magnitude below regulatory limits, they consequently are vulnerable to high loading rates. This becomes a serious handicap in radioactive systems when filter change-out is required at an unacceptably high rate. The Process Experimental Pilot Plant (PREPP) incineration system is designed for processing retrieved low level mixed hazardous waste. It has a wet offgasmore » treatment system consisting of a Quencher, Venturi Scrubber, Entrainment Eliminator, Mist Eliminator, two stages of HEPA filters, and induced draft fans. During previous tests, it was noted that the offgas filters loaded with particulate at a rate requiring replacement as often as every four hours. During 1988, PREPP conducted a series of tests which included an investigation of the causes of heavy particulate accumulation on the offgas filters in relation to various operating parameters. This was done by measuring the particulate concentrations in the offgas system, primarily as a function of scrub solution salt concentration, waste feed rate, and offgas flow rate. 2 figs., 9 tabs.« less

Incorporation of a Chemical Equilibrium Equation of State into LOCI-Chem

NASA Technical Reports Server (NTRS)

Cox, Carey F.

2005-01-01

Renewed interest in development of advanced high-speed transport, reentry vehicles and propulsion systems has led to a resurgence of research into high speed aerodynamics. As this flow regime is typically dominated by hot reacting gaseous flow, efficient models for the characteristic chemical activity are necessary for accurate and cost effective analysis and design of aerodynamic vehicles that transit this regime. The LOCI-Chem code recently developed by Ed Luke at Mississippi State University for NASA/MSFC and used by NASA/MSFC and SSC represents an important step in providing an accurate, efficient computational tool for the simulation of reacting flows through the use of finite-rate kinetics [3]. Finite rate chemistry however, requires the solution of an additional N-1 species mass conservation equations with source terms involving reaction kinetics that are not fully understood. In the equilibrium limit, where the reaction rates approach infinity, these equations become very stiff. Through the use of the assumption of local chemical equilibrium the set of governing equations is reduced back to the usual gas dynamic equations, and thus requires less computation, while still allowing for the inclusion of reacting flow phenomenology. The incorporation of a chemical equilibrium equation of state module into the LOCI-Chem code was the primary objective of the current research. The major goals of the project were: (1) the development of a chemical equilibrium composition solver, and (2) the incorporation of chemical equilibrium solver into LOCI-Chem. Due to time and resource constraints, code optimization was not considered unless it was important to the proper functioning of the code.

Flagella-Driven Flows Circumvent Diffusive Bottlenecks that Inhibit Metabolite Exchange

NASA Astrophysics Data System (ADS)

Short, Martin; Solari, Cristian; Ganguly, Sujoy; Kessler, John; Goldstein, Raymond; Powers, Thomas

2006-03-01

The evolution of single cells to large and multicellular organisms requires matching the organisms' needs to the rate of exchange of metabolites with the environment. This logistic problem can be a severe constraint on development. For organisms with a body plan that approximates a spherical shell, such as colonies of the volvocine green algae, the required current of metabolites grows quadratically with colony radius whereas the rate at which diffusion can exchange metabolites grows only linearly with radius. Hence, there is a bottleneck radius beyond which the diffusive current cannot keep up with metabolic demands. Using Volvox carteri as a model organism, we examine experimentally and theoretically the role that advection of fluid by surface-mounted flagella plays in enhancing nutrient uptake. We show that fluid flow driven by the coordinated beating of flagella produces a convective boundary layer in the concentration of a diffusing solute which in turn renders the metabolite exchange rate quadratic in the colony radius. This enhanced transport circumvents the diffusive bottleneck, allowing increase in size and thus evolutionary transitions to multicellularity in the Volvocales.

Role of surface properties in bacterial attachment

NASA Astrophysics Data System (ADS)

Conrad, Jacinta; Sharma, Sumedha

2014-03-01

Bacterial biofilms foul a wide range of engineered surfaces, from pipelines to membranes to biomedical implants, and lead to deleterious costs for industry and for human health. Designing strategies to reduce bacterial fouling requires fundamental understanding of mechanisms by which bacteria attach to surfaces. We investigate the attachment of Escherichia coli on silanized glass surfaces during flow through a linear channel at flow rates of 0.1-1 mL/min using confocal microscopy. We deposit self-assembled monolayers of organosilanes on glass and track the position and orientation of bacteria deposited on these surfaces during flow using high-throughput image processing algorithms. Here, we report differences in deposition rate and surface-tethered motion of cells as a function of surface charge and surface energy, suggesting that attachment of bacteria on these engineered surfaces is dominated by different physical mechanisms.

Modification of the BioMedicus centrifugal pump to provide continuous irrigation for neuroendoscopy: technical note.

PubMed

Koueik, Joyce; Rocque, Brandon G; Henry, Jordan; Bragg, Taryn; Paul, Jennifer; Iskandar, Bermans J

2018-02-01

Continuous irrigation is an important adjunct for successful intraventricular endoscopy, particularly for complex cases. It allows better visualization by washing out blood and debris, improves navigation by expanding the ventricles, and assists with tissue dissection. A method of irrigation delivery using a centrifugal pump designed originally for cardiac surgery is presented. The BioMedicus centrifugal pump has the desirable ability to deliver a continuous laminar flow of fluid that excludes air from the system. A series of modifications to the pump tubing was performed to adapt it to neuroendoscopy. Equipment testing determined flow and pressure responses at various settings and simulated clinical conditions. The pump was then studied clinically in 11 endoscopy cases and eventually used in 310 surgical cases. Modifications of the pump tubing allowed for integration with different endoscopy systems. Constant flow rates were achieved with and without surgical instruments through the working ports. Optimal flow rates ranged between 30 and 100 ml/min depending on endoscope size. Intraoperative use was well tolerated with no permanent morbidity and showed consistent flow rates, minimal air accumulation, and seamless irrigation bag replacement during prolonged surgery. Although the pump is equipped with an internal safety mechanism to protect against pressure buildup when outflow obstructions occur, equipment testing revealed that flow cessation is not instantaneous enough to protect against sudden intracranial pressure elevation. A commonly available cardiac pump system was modified to provide continuous irrigation for intraventricular endoscopy. The system alleviates the problems of inconsistent flow rates, air in the irrigation lines, and delays in changing irrigation bags, thereby optimizing patient safety and surgical efficiency. Safe use of the pump requires good ventricular outflow and, clearly, sound surgical judgment.

Design, Integration, Certification and Testing of the Orion Crew Module Propulsion System

NASA Technical Reports Server (NTRS)

McKay, Heather; Freeman, Rich; Cain, George; Albright, John D.; Schoenberg, Rich; Delventhal, Rex

2014-01-01

The Orion Multipurpose Crew Vehicle (MPCV) is NASA's next generation spacecraft for human exploration of deep space. Lockheed Martin is the prime contractor for the design, development, qualification and integration of the vehicle. A key component of the Orion Crew Module (CM) is the Propulsion Reaction Control System, a high-flow hydrazine system used during re-entry to orient the vehicle for landing. The system consists of a completely redundant helium (GHe) pressurization system and hydrazine fuel system with monopropellant thrusters. The propulsion system has been designed, integrated, and qualification tested in support of the Orion program's first orbital flight test, Exploration Flight Test One (EFT-1), scheduled for 2014. A subset of the development challenges and lessons learned from this first flight test campaign will be discussed in this paper for consideration when designing future spacecraft propulsion systems. The CONOPS and human rating requirements of the CM propulsion system are unique when compared with a typical satellite propulsion reaction control system. The system requires a high maximum fuel flow rate. It must operate at both vacuum and sea level atmospheric pressure conditions. In order to meet Orion's human rating requirements, multiple parts of the system must be redundant, and capable of functioning after spacecraft system fault events.

Tracking lava flow emplacement on the east rift zone of Kilauea, Hawai'i with InSAR coherence

NASA Astrophysics Data System (ADS)

Dietterich, H. R.; Schmidt, D. A.; Poland, M. P.; Cashman, K. V.

2010-12-01

Remote sensing of lava flows from the Pu`u `O`o-Kupaianaha eruption on the east rift zone of Kilauea serves to document the ongoing eruption, while yielding insights into how lava flow fields develop. InSAR is widely used to measure deformation by detecting minute changes in ground surfaces that stay correlated during repeat observations. The eruption and emplacement of fresh lava on the surface, however, disrupts the coherence of the radar echoes, allowing the area of these flows to be mapped with InSAR coherence images. We use InSAR correlation to visualize surface flow activity from 2003-2010 in order to quantify eruption rates and explore lava flow behavior from emplacement onward. This method for mapping flows does not require daylight, cloudless skies, or access to the active flow fields that is necessary for traditional visual surveys. We produce coherence maps for hundreds of 35 to 105-day periods from twelve tracks of ENVISAT SAR data using the GAMMA software package. By combining these coherence maps we create a unique dataset with which to develop this technique and amass lava flow observations. Where correlation images overlap in time, they are summed and normalized to derive a time series of surface coherence with a spatial resolution of 20 meters and a temporal resolution of as little as a few days. We identify existing stable flows by their high radar coherence, and determine a coherence threshold that is applied to each correlation image. This threshold is calibrated so as to reduce the effects of varying baseline, time duration, and atmospheric effects between images, as well as decorrelation due to vegetation. The final images illustrate lava flow activity that corresponds well with surface flow outlines and tube locations recorded by the USGS mapping effort. The InSAR-derived results serve to enhance these traditional maps by documenting pixel-scale changes over time. When compared with forward looking infrared (FLIR) thermal imagery, pixel decorrelation can be related to specific styles of activity, including surface breakouts or deformation, where field examination is difficult. We analyze these detailed snapshots of the flows to derive estimates of flow parameters, including effusion rates, lava flow areas and volumes, and surface lava flow activity over time, which provides a means of examining controls on flow paths, advance rates, and morphologies. We find that once emplaced, flows remain decorrelated for months before becoming correlated again in a piecewise fashion, suggesting that correlation rate may be dependent on thickness and cooling rate. As the eruption continues, this ever-expanding dataset has great potential for remotely capturing quantitative data from an active flow field and improving our knowledge of lava flows and their hazards.

Optimal Flow Control Design

NASA Technical Reports Server (NTRS)

Allan, Brian; Owens, Lewis

2010-01-01

In support of the Blended-Wing-Body aircraft concept, a new flow control hybrid vane/jet design has been developed for use in a boundary-layer-ingesting (BLI) offset inlet in transonic flows. This inlet flow control is designed to minimize the engine fan-face distortion levels and the first five Fourier harmonic half amplitudes while maximizing the inlet pressure recovery. This concept represents a potentially enabling technology for quieter and more environmentally friendly transport aircraft. An optimum vane design was found by minimizing the engine fan-face distortion, DC60, and the first five Fourier harmonic half amplitudes, while maximizing the total pressure recovery. The optimal vane design was then used in a BLI inlet wind tunnel experiment at NASA Langley's 0.3-meter transonic cryogenic tunnel. The experimental results demonstrated an 80-percent decrease in DPCPavg, the reduction in the circumferential distortion levels, at an inlet mass flow rate corresponding to the middle of the operational range at the cruise condition. Even though the vanes were designed at a single inlet mass flow rate, they performed very well over the entire inlet mass flow range tested in the wind tunnel experiment with the addition of a small amount of jet flow control. While the circumferential distortion was decreased, the radial distortion on the outer rings at the aerodynamic interface plane (AIP) increased. This was a result of the large boundary layer being distributed from the bottom of the AIP in the baseline case to the outer edges of the AIP when using the vortex generator (VG) vane flow control. Experimental results, as already mentioned, showed an 80-percent reduction of DPCPavg, the circumferential distortion level at the engine fan-face. The hybrid approach leverages strengths of vane and jet flow control devices, increasing inlet performance over a broader operational range with significant reduction in mass flow requirements. Minimal distortion level requirements are met using vanes alone, avoiding engine stall and increasing robustness of this hybrid inlet flow control approach. This design applies to aerospace applications needing flush-mounted boundary-layer-ingesting inlets.

Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants.

PubMed

Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

2014-11-01

Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier-Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. © 2014 Wiley Periodicals, Inc.

Viscid/inviscid interaction analysis of thrust augmenting ejectors

NASA Technical Reports Server (NTRS)

Bevilacqua, P. M.; Dejoode, A. D.

1979-01-01

A method was developed for calculating the static performance of thrust augmenting ejectors by matching a viscous solution for the flow through the ejector to an inviscid solution for the flow outside the ejector. A two dimensional analysis utilizing a turbulence kinetic energy model is used to calculate the rate of entrainment by the jets. Vortex panel methods are then used with the requirement that the ejector shroud must be a streamline of the flow induced by the jets to determine the strength of circulation generated around the shroud. In effect, the ejector shroud is considered to be flying in the velocity field of the jets. The solution is converged by iterating between the rate of entrainment and the strength of the circulation. This approach offers the advantage of including external influences on the flow through the ejector. Comparisons with data are presented for an ejector having a single central nozzle and Coanda jet on the walls. The accuracy of the matched solution is found to be especially sensitive to the jet flap effect of the flow just downstream of the ejector exit.

Real time closed loop control of an Ar and Ar/O2 plasma in an ICP

NASA Astrophysics Data System (ADS)

Faulkner, R.; Soberón, F.; McCarter, A.; Gahan, D.; Karkari, S.; Milosavljevic, V.; Hayden, C.; Islyaikin, A.; Law, V. J.; Hopkins, M. B.; Keville, B.; Iordanov, P.; Doherty, S.; Ringwood, J. V.

2006-10-01

Real time closed loop control for plasma assisted semiconductor manufacturing has been the subject of academic research for over a decade. However, due to process complexity and the lack of suitable real time metrology, progress has been elusive and genuine real time, multi-input, multi-output (MIMO) control of a plasma assisted process has yet to be successfully implemented in an industrial setting. A Splasma parameter control strategy T is required to be adopted whereby process recipes which are defined in terms of plasma properties such as critical species densities as opposed to input variables such as rf power and gas flow rates may be transferable between different chamber types. While PIC simulations and multidimensional fluid models have contributed considerably to the basic understanding of plasmas and the design of process equipment, such models require a large amount of processing time and are hence unsuitable for testing control algorithms. In contrast, linear dynamical empirical models, obtained through system identification techniques are ideal in some respects for control design since their computational requirements are comparatively small and their structure facilitates the application of classical control design techniques. However, such models provide little process insight and are specific to an operating point of a particular machine. An ideal first principles-based, control-oriented model would exhibit the simplicity and computational requirements of an empirical model and, in addition, despite sacrificing first principles detail, capture enough of the essential physics and chemistry of the process in order to provide reasonably accurate qualitative predictions. This paper will discuss the development of such a first-principles based, control-oriented model of a laboratory inductively coupled plasma chamber. The model consists of a global model of the chemical kinetics coupled to an analytical model of power deposition. Dynamics of actuators including mass flow controllers and exhaust throttle are included and sensor characteristics are also modelled. The application of this control-oriented model to achieve multivariable closed loop control of specific species e.g. atomic Oxygen and ion density using the actuators rf power, Oxygen and Argon flow rates, and pressure/exhaust flow rate in an Ar/O2 ICP plasma will be presented.

The Characteristics of Heat Flow in the Ryukyu Trench-Arc-Basin System: Constraints on Thermal Structure and Evolution of the Okinawa Trough

NASA Astrophysics Data System (ADS)

Zhang, L.

2017-12-01

Heat flow is an important constraint to study the thermal structure and evolution in modeling experiments. Based on the surface heat flow map and recent geochemistry results, a 2D transient heat conduction-advection model is used to investigate how the effects of sedimentation rate, magmatic intrusion, extension duration and rate on the surface heat flow distribution of the Okinawa Trough. Surface heat flow distribution map is interpolated based on a data set with 664 measurements in the Ryukyu trench-arc-basin system. The map shows an obviously correspondence between heat flows and tectonic zones, characterized by belts in E-W and blocks in S-N. The heat flow is extremely high and variable in the central Okinawa Trough (COT). The lowest heat values are distributed in the northwest of West Philippine Sea near the Ryukyu Trench. This phenomenon is likely related to increasing hydrothermal circulation of cold water into the upper portion of the incoming plate because of bend-faulting and little sediment coverage. Simulation results show that (1) High sedimentation rate can reduce heat flow by 30-35 % in the southern OT. (2) The sedimentation-corrected heat flow indicates that mantle upwelling occurred in the whole OT. The isotherm of 1000°C reaches to the depth of 19 km in the axil of the COT after 10 Ma. (3) The heat flow can be improved drastically by dyke intrusion along normal faults, but subsequent decreases rapidly about 15% after 0.1 Ma, which indicates the age of dyke intrusion under the Iheya area is younger than 0.5 Ma, and the depth is shallower than 2 km. Moreover, the magma fluid upward migrated along the magma conduits is required for the extremely high heat flow and its Darcy velocity can reach to 9 cm/yr. Based on the distribution of heat flow, we suggest that there is a different evolution model between the central- northern OT and the southern. The time of rifting in the NOT-COT began at 10 Ma with the mean rate of 0.4 cm/yr, while the rifting of the SOT started from 6 Ma with higher rate of 0.6 cm/yr.

Two-Stage Centrifugal Fan

NASA Technical Reports Server (NTRS)

Converse, David

2011-01-01

Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan rotor diameter. The invention is to put two radially oriented stages on a single disk. Flow enters the first stage from the center; energy is imparted to the flow in the first stage blades, the flow is redirected some amount opposite to the direction of rotation in the fixed stators, and more energy is imparted to the flow in the second- stage blades. Without increasing either rotational speed or disk diameter, it is believed that as much as 50 percent more DP can be achieved with this design than with an ordinary, single-stage centrifugal design. This invention is useful primarily for fans having relatively low flow rates with relatively high pressure rise requirements.

Effect of reference conditions on flow rate, modifier fraction and retention in supercritical fluid chromatography.

PubMed

De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

2016-08-12

When using compressible mobile phases such as fluidic CO2, the density, the volumetric flow rates and volumetric fractions are pressure dependent. The pressure and temperature definition of these volumetric parameters (referred to as the reference conditions) may alter between systems, manufacturers and operating conditions. A supercritical fluid chromatography system was modified to operate in two modes with different definition of the eluent delivery parameters, referred to as fixed and variable mode. For the variable mode, the volumetric parameters are defined with reference to the pump operating pressure and actual pump head temperature. These conditions may vary when, e.g. changing the column length, permeability, flow rate, etc. and are thus variable reference conditions. For the fixed mode, the reference conditions were set at 150bar and 30°C, resulting in a mass flow rate and mass fraction of modifier definition which is independent of the operation conditions. For the variable mode, the mass flow rate of carbon dioxide increases with system pump operating pressure, decreasing the fraction of modifier. Comparing the void times and retention factor shows that the deviation between the two modes is almost independent of modifier percentage, but depends on the operating pressure. Recalculating the set volumetric fraction of modifier to the mass fraction results in the same retention behaviour for both modes. This shows that retention in SFC can be best modelled using the mass fraction of modifier. The fixed mode also simplifies method scaling as it only requires matching average column pressure. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania

PubMed Central

Kang, Mary; Kanno, Cynthia M.; Reid, Matthew C.; Zhang, Xin; Mauzerall, Denise L.; Celia, Michael A.; Chen, Yuheng; Onstott, Tullis C.

2014-01-01

Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells (“controls”) in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10−6 kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10−3 kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4–7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories. PMID:25489074

Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.

PubMed

Kang, Mary; Kanno, Cynthia M; Reid, Matthew C; Zhang, Xin; Mauzerall, Denise L; Celia, Michael A; Chen, Yuheng; Onstott, Tullis C

2014-12-23

Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.

Influence of oxygen concentration, fuel composition, and strain rate on synthesis of carbon nanomaterials

NASA Astrophysics Data System (ADS)

Hou, Shuhn-Shyurng; Huang, Wei-Cheng

2015-02-01

This paper investigates the influence of flame parameters including oxygen concentration, fuel composition, and strain rate on the synthesis of carbon nanomaterials in opposed-jet ethylene diffusion flames with or without rigid-body rotation. In the experiments, a mixture of ethylene and nitrogen was introduced from the upper burner; meanwhile, a mixture of oxygen and nitrogen was supplied from the lower burner. A nascent nickel mesh was used as the catalytic metal substrate to collect deposited materials. With non-rotating opposed-jet diffusion flames, carbon nanotubes (CNTs) were successfully produced for oxygen concentrations in the range of 21-50 % at a fixed ethylene concentration of 20 %, and for ethylene concentrations ranging from 14 to 24 % at a constant oxygen concentration of 40 %. With rotating opposed-jet diffusion flames, the strain rate was varied by adjusting the angular velocities of the upper and lower burners. The strain rate governed by flow rotation greatly affects the synthesis of carbon nanomaterials [i.e., CNTs and carbon nano-onions (CNOs)] either through the residence time or carbon sources available. An increase in the angular velocity lengthened the residence time of the flow and thus caused the diffusion flame to experience a decreased strain rate, which in turn produced more carbon sources. The growth of multi-walled CNTs was achieved for the stretched flames experiencing a higher strain rate [i.e., angular velocity was equal to 0 or 1 rotations per second (rps)]. CNOs were synthesized at a lower strain rate (i.e., angular velocity was in the range of 2-5 rps). It is noteworthy that the strain rate controlled by flow rotation greatly influences the fabrication of carbon nanostructures owing to the residence time as well as carbon source. Additionally, more carbon sources and higher temperature are required for the synthesis of CNOs compared with those required for CNTs (i.e., about 605-625 °C for CNTs and 700-800 °C for CNOs).

Efficiency of Silver Impregnated Porous Pot (SIPP) Filters for Production of Clean Potable Water

PubMed Central

Mahlangu, Oranso; Mamba, Bhekie; Momba, Maggie

2012-01-01

The Silver Impregnated Porous Pot (SIPP) filter is a product of the Tshwane University of Technology manufactured for the production of safe drinking water at a household (home) level. Two SIPP devices were assessed for the reduction efficiency of chemical contaminants such as calcium, magnesium, iron, arsenic, fluorides and total organic carbon (TOC) as well as microbial contaminants from environmental samples. Turbidity change after filtration, together with correlation between chlorophyll a in the feed water and SIPP’s flow rates were also evaluated in order to give comprehensive guidelines on the quality of intake water that could be filtered through the filter without causing a significant decrease in flow rate. The SIPP filters removed contaminants from environmental water samples as follows: 70% to 92% iron, 36% to 68% calcium, 42% to 82% arsenic, 39% to 98% magnesium, 39% to 95% fluorides, 12% to 35% TOC and 45% to 82% turbidity. The SIPP filters had initial flow rates of 1 L/h to 4 L/h but the flow rates dropped to 0.5 L/h with an increase in cumulative volume of intake water as the filter was used. Turbidity and chemical contaminant reduction rates decreased with accumulating volume of intake water but the filter removed Ca, Fe and Mg to levels that comply with the South African National Standards (SANS 241) and the World Health Organization (WHO) guideline values. However, the SIPP filters cannot produce enough water to satisfy the daily drinking water requirement of a typical household (25 L/p·d). Chlorophyll a was associated with a decrease in the flow rate through the SIPP filters. PMID:23202668

Efficiency of Silver Impregnated Porous Pot (SIPP) filters for production of clean potable water.

PubMed

Mahlangu, Oranso; Mamba, Bhekie; Momba, Maggie

2012-08-24

The Silver Impregnated Porous Pot (SIPP) filter is a product of the Tshwane University of Technology manufactured for the production of safe drinking water at a household (home) level. Two SIPP devices were assessed for the reduction efficiency of chemical contaminants such as calcium, magnesium, iron, arsenic, fluorides and total organic carbon (TOC) as well as microbial contaminants from environmental samples. Turbidity change after filtration, together with correlation between chlorophyll a in the feed water and SIPP's flow rates were also evaluated in order to give comprehensive guidelines on the quality of intake water that could be filtered through the filter without causing a significant decrease in flow rate. The SIPP filters removed contaminants from environmental water samples as follows: 70% to 92% iron, 36% to 68% calcium, 42% to 82% arsenic, 39% to 98% magnesium, 39% to 95% fluorides, 12% to 35% TOC and 45% to 82% turbidity. The SIPP filters had initial flow rates of 1 L/h to 4 L/h but the flow rates dropped to 0.5 L/h with an increase in cumulative volume of intake water as the filter was used. Turbidity and chemical contaminant reduction rates decreased with accumulating volume of intake water but the filter removed Ca, Fe and Mg to levels that comply with the South African National Standards (SANS 241) and the World Health Organization (WHO) guideline values. However, the SIPP filters cannot produce enough water to satisfy the daily drinking water requirement of a typical household (25 L/p·d). Chlorophyll a was associated with a decrease in the flow rate through the SIPP filters.

Extraction of dye from aqueous solution in rotating packed bed.

PubMed

Modak, Jayant B; Bhowal, Avijit; Datta, Siddhartha

2016-03-05

The influence of centrifugal acceleration on mass transfer rates in liquid-liquid extraction was investigated experimentally in rotating packed bed (RPB) contactor. The extraction of methyl red using xylene was studied in the equipment. The effect of rotational speed (300-900rpm), flow rate of the aqueous (4.17-20.8×10(-6)m(3)/s), and organic phase (0.83-2.5×10(-6)m(3)/s) on the mass transfer performance was examined. The maximum stage efficiency attained was ∼0.98 at aqueous to organic flow rate ratio of 10. The results suggest that contactor volume required to carry out a given separation can be reduced by an order of magnitude with RPB in comparison to conventional extractors. Copyright © 2015 Elsevier B.V. All rights reserved.

CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime.

PubMed

Sánchez, F; Rey, H; Viedma, A; Nicolás-Pérez, F; Kaiser, A S; Martínez, M

2018-08-01

Due to the aeration system, biological reactors are the most energy-consuming facilities of convectional WWTPs. Many biological reactors work under intermittent aeration regime; the optimization of the aeration process (air diffuser layout, air flow rate per diffuser, aeration length …) is necessary to ensure an efficient performance; satisfying the effluent requirements with the minimum energy consumption. This work develops a CFD modelling of an activated sludge reactor (ASR) which works under intermittent aeration regime. The model considers the fluid dynamic and biological processes within the ASR. The biological simulation, which is transient, takes into account the intermittent aeration regime. The CFD modelling is employed for the selection of the aeration system of an ASR. Two different aeration configurations are simulated. The model evaluates the aeration power consumption necessary to satisfy the effluent requirements. An improvement of 2.8% in terms of energy consumption is achieved by modifying the air diffuser layout. An analysis of the influence of the air flow rate per diffuser on the ASR performance is carried out. The results show a reduction of 14.5% in the energy consumption of the aeration system when the air flow rate per diffuser is reduced. The model provides an insight into the aeration inefficiencies produced within ASRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Model modifications for simulation of flow through stratified rocks in eastern Ohio

USGS Publications Warehouse

Helgesen, J.O.; Razem, A.C.; Larson, S.P.

1982-01-01

A quasi three-dimensional groundwater flow model is being used as part of a study to determine impacts of coal-strip mining on local hydrologic systems. Modifications to the model were necessary to simulate local hydrologic conditions properly. Perched water tables required that the method of calculating vertical flow rate be changed. A head-dependent spring-discharge function and a head-dependent stream aquifer-interchange function were added to the program. Modifications were also made to allow recharge from precipitation to any layer. The modified program, data deck instructions, and sample input and output are presented. (USGS)

Water Pipeline Monitoring and Leak Detection using Flow Liquid Meter Sensor

NASA Astrophysics Data System (ADS)

Rahmat, R. F.; Satria, I. S.; Siregar, B.; Budiarto, R.

2017-04-01

Water distribution is generally installed through underground pipes. Monitoring the underground water pipelines is more difficult than monitoring the water pipelines located on the ground in open space. This situation will cause a permanent loss if there is a disturbance in the pipeline such as leakage. Leaks in pipes can be caused by several factors, such as the pipe’s age, improper installation, and natural disasters. Therefore, a solution is required to detect and to determine the location of the damage when there is a leak. The detection of the leak location will use fluid mechanics and kinematics physics based on harness water flow rate data obtained using flow liquid meter sensor and Arduino UNO as a microcontroller. The results show that the proposed method is able to work stably to determine the location of the leak which has a maximum distance of 2 metres, and it’s able to determine the leak location as close as possible with flow rate about 10 litters per minute.

Temporal flow instability for Magnus-Robins effect at high rotation rates

NASA Astrophysics Data System (ADS)

Sengupta, T. K.; Kasliwal, A.; de, S.; Nair, M.

2003-06-01

The lift and drag coefficients of a circular cylinder, translating and spinning at a supercritical rate is studied theoretically to explain the experimentally observed violation of maximum mean lift coefficient principle, that was proposed heuristically by Prandtl on the basis of inviscid flow model. It is also noted experimentally that flow past a rotating and translating cylinder experiences temporal instability-a fact not corroborated by any theoretical studies so far. In the present paper we report very accurate solution of Navier-Stokes equation that displays the above-mentioned instability and the violation of the maximum limit. The calculated lift coefficient exceeds the limit of /4π, instantaneously as well as in time-averaged sense. The main purpose of the present paper is to explain the observed temporal instability sequence in terms of a new theory of instability based on full Navier-Stokes equation that does not require making any assumption about the flow field, unlike other stability theories.

Experimental characterization of novel microdiffuser elements

NASA Astrophysics Data System (ADS)

Ehrlich, L.; Punch, J.; Jeffers, N.; Stafford, J.

2014-07-01

Micropumps can play a significant role in thermal management applications, as a component of microfluidic cooling systems. For next-generation high density optical communication systems, in particular, heat flux levels are sufficiently high to require a microfluidic circuit for cooling. Valveless piezoelectrically-actuated micropumps are a particularly promising technology to be deployed for this application. These pumps exploit the asymmetric flow behaviour of microdiffusers to achieve net flow. They feature no rotating or contacting parts, which make them intrinsically reliable in comparison to micropumps with active valves. In this paper, two novel microdiffuser elements are reported and characterized. The micropumps were fabricated using a 3D Printer. Each single diffuser had a length of 1800 pm and a depth of 400 pm. An experimental characterization was conducted in which the flow rate and differential pressure were measured as a function of operating frequency. In comparison with standard diffuser, both elements showed an increase in differential pressure in the range of 40 - 280 %, but only one of the elements exhibited an improved flow rate, of about 85 %.

Development of a high-resolution automatic digital (urine/electrolytes) flow volume and rate measurement system of miniature size

NASA Technical Reports Server (NTRS)

Liu, F. F.

1975-01-01

To aid in the quantitative analysis of man's physiological rhythms, a flowmeter to measure circadian patterns of electrolyte excretion during various environmental stresses was developed. One initial flowmeter was designed and fabricated, the sensor of which is the approximate size of a wristwatch. The detector section includes a special type of dielectric integrating type sensor which automatically controls, activates, and deactivates the flow sensor data output by determining the presence or absence of fluid flow in the system, including operation under zero-G conditions. The detector also provides qualitative data on the composition of the fluid. A compact electronic system was developed to indicate flow rate as well as total volume per release or the cumulative volume of several releases in digital/analog forms suitable for readout or telemetry. A suitable data readout instrument is also provided. Calibration and statistical analyses of the performance functions required of the flowmeter were also conducted.

Lox breathing system with gas permeable-liquid impermeable heat exchange and delivery hose

DOEpatents

Hall, Mark N.

1996-01-01

Life support apparatus composed of: a garment (2): for completely enclosing a wearer and constructed for preventing passage of gas from the environment surrounding the garment (2); a portable receptacle (6) holding a quantity of an oxygen-containing fluid in liquid state, the fluid being in a breathable gaseous; state when at standard temperature and pressure; a fluid flow member (16) secured within the garment (2) and coupled to the receptacle (6) for conducting the fluid in liquid state from the receptacle (6) to the interior of the garment (2); and a fluid flow control device (14) connected for causing fluid to flow from the receptacle (6) to the fluid flow member (16) at a rate determined by the breathable air requirement of the wearer, wherein fluid in liquid state is conducted into the interior of the garment (2) at a rate to be vaporized and heated to a breathable temperature by body heat produced by the wearer.

Satellite Propellant Pump Research

NASA Technical Reports Server (NTRS)

Schneider, Steven J.; Veres, Joseph P.; Hah, Chunill; Nerone, Anthony L.; Cunningham, Cameron C.; Kraft, Thomas G.; Tavernelli, Paul F.; Fraser, Bryan

2005-01-01

NASA Glenn initiated a satellite propellant pump technology demonstration program. The goal was to demonstrate the technologies for a 60 percent efficient pump at 1 gpm flow rate and 500 psia pressure rise. The pump design and analysis used the in-house developed computer codes named PUMPA and HPUMP3D. The requirements lead to a 4-stage impeller type pump design with a tip diameter of 0.54 inches and a rotational speed of 57,000 rpm. Analyses indicated that flow cavitation was not a problem in the design. Since the flow was incompressible, the stages were identical. Only the 2-stage pump was designed, fabricated, assembled, and tested for demonstration. Water was selected as the surrogate fluid for hydrazine in this program. Complete mechanical design including stress and dynamic analyses were conducted. The pump was driven by an electric motor directly coupled to the impellers. Runs up to 57,000 rpm were conducted, where a pressure rise of 200 psia at a flow rate of 0.8 gpm was measured to validate the design effort.

Effects of Convective Solute and Impurity Transport in Protein Crystal Growth

NASA Technical Reports Server (NTRS)

Vekilov, Peter G.; Thomas, Bill R.; Rosenberger, Franz

1998-01-01

High-resolution optical interferometry was used to investigate the effects of forced solution convection on the crystal growth kinetics of the model protein lysozyme. Most experiments were conducted with 99.99% pure protein solutions. To study impurity effects, approx. 1% of lysozyme dimer (covalently bound) was added in some cases. We show that the unsteady kinetics, corresponding to bunching of growth steps, can be characterized by the Fourier components of time traces of the growth rate. Specific Fourier spectra are uniquely determined by the solution conditions (composition, temperature, and flow rate) and the growth layer source activity. We found that the average step velocity and growth rate increase by approx. I0% with increasing flow rate, as a result of the enhanced solute supply to the interface. More importantly, faster convective transport results in lower fluctuation amplitudes. This observation supports our rationale for system-dependent effects of transport on the structural perfection of protein crystals. We also found that solution flow rates greater than 500 microns/s result in stronger fluctuations while the average growth rate is decreased. This can lead to growth cessation at low supersaturations. With the intentionally contaminated solutions, these undesirable phenomena occurred at about half the flow rates required in pure solutions. Thus, we conclude that they are due to enhanced convective supply of impurities that are incorporated into the crystal during growth. Furthermore, we found that the impurity effects are reduced at higher crystal growth rates. Since the exposure time of terraces is inversely proportional to the growth rate, this observation suggests that the increased kinetics instability results from impurity adsorption on the interface. Finally, we provide evidence relating earlier observations of "slow protein crystal growth kinetics" to step bunch formation in response to nonsteady step generation.

Multi-Velocity Encoding Four-Dimensional Flow Magnetic Resonance Imaging in the Assessment of Chronic Aortic Dissection

PubMed Central

Sherrah, Andrew G.; Callaghan, Fraser M.; Puranik, Rajesh; Jeremy, Richmond W.; Bannon, Paul G.; Vallely, Michael P.; Grieve, Stuart M.

2017-01-01

Background Chronic descending thoracic aortic dissection (CDTAD) following surgical repair of ascending aortic dissection requires long-term imaging surveillance. We investigated four-dimensional (4D)-flow magnetic resonance imaging (MRI) with a novel multi-velocity encoding (multi-VENC) technique as an emerging clinical method enabling the dynamic quantification of blood volume and velocity throughout the cardiac cycle. Methods Patients with CDTAD (n = 10; mean age, 55.1 years; standard deviation (SD) 10.8) and healthy volunteers (n = 9; mean age, 37.1 years; SD 11.4; p < 0.01) underwent 3T MRI, and standard views and 4D-flow data were obtained. Flow measurements were made in selected regions of interest within the ascending and descending thoracic aorta. Results The overall flow profile at peak systole was reduced in the false lumen (FL) compared with the true lumen (TL) and normal aortas (p < 0.05 for velocity < 0.4 m/s). Peak systolic flow rate per aortic lumen area (mL/s/cm2) was lower in the FL than in the TL (p < 0.05), and both rates were lower than that of control aortas (p < 0.05). Blood flow reversal was higher in the FL than in the TL throughout the descending aorta in CDTAD patients (p < 0.05). A derived pulsatility index was elevated in the TL compared with that in the FL in CDTAD patients. Generated pathline images demonstrated flow patterns in detail, including sites of communication between the true and FL. Conclusions 4D-flow MRI revealed FL blood flow and reduced blood flow velocity and flow rate in the TL of CDTAD patients compared with normal aortas of healthy participants. Thus, multi-VENC 4D-flow MRI could serve as an adjunct in the long-term assessment of CDTAD following surgical repair of ascending aortic dissection. PMID:29675440

40 CFR 63.526 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (D) Design analysis based on accepted chemical engineering principles, measurable process parameters... purpose of determining de minimis status for emission points, engineering assessment may be used to... expected to yield the highest flow rate and concentration. Engineering assessment includes, but is not...

40 CFR 63.526 - Monitoring requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (D) Design analysis based on accepted chemical engineering principles, measurable process parameters... purpose of determining de minimis status for emission points, engineering assessment may be used to... expected to yield the highest flow rate and concentration. Engineering assessment includes, but is not...

From catastrophic acceleration to deceleration of liquid plugs in prewetted capillary tubes

NASA Astrophysics Data System (ADS)

Magniez, Juan; Baudoin, Michael; Zoueshtiagh, Farzam; Lemac/Lics Team

2016-11-01

Liquid/gas flows in capillaries are involved in a multitude of systems including flow in porous media, petroleum extraction, imbibition of paper or flows in pulmonary airways in pathological conditions. Liquid plugs, witch compose the biphasic flows, can have a dramatic impact on patients with pulmonary obstructive diseases, since they considerably alter the circulation of air in the airways and thus can lead to severe breathing difficulties. Here, the dynamics of liquid plugs in prewetted capillary tube is investigated experimentally and theoretically, with a particular emphasis on the role of the prewetting films and of the driving condition (constant flow rate, constant pressure). For both driving conditions, the plugs can either experience a continuous increase or decrease of their size. While this phenomenon is regular in the case of imposed flow rate, a constant pressure head can lead to a catastrophic acceleration of the plug and eventually its rupture or a dramatic increase of the plug size. A theoretical model is proposed to explain the transition between theses two regimes. These results give a new insight on the critical pressure required for airways obstruction and reopening. IEMN, International Laboratory LEMAC/LICS, UMR CNRS 8520, University of Lille.

Multigrid schemes for viscous hypersonic flows

NASA Technical Reports Server (NTRS)

Swanson, R. C.; Radespiel, R.

1993-01-01

Several multigrid schemes are considered for the numerical computation of viscous hypersonic flows. For each scheme, the basic solution algorithm employs upwind spatial discretization with explicit multistage time stepping. Two-level versions of the various multigrid algorithms are applied to the two-dimensional advection equation, and Fourier analysis is used to determine their damping properties. The capabilities of the multigrid methods are assessed by solving two different hypersonic flow problems. Some new multigrid schemes, based on semicoarsening strategies, are shown to be quite effective in relieving the stiffness caused by the high-aspect-ratio cells required to resolve high Reynolds number flows. These schemes exhibit good convergence rates for Reynolds numbers up to 200 x 10(exp 6).

Flow and Heat Transfer Tests in New Loop at 2757 kPa (400 psi)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woloshun, Keith Albert

2016-06-13

A helium flow and heat transfer experiment has been designed for the new helium flow loop facility at LANL. This new facility is centered on an Aerzen GM 12.4 Root’s blower, selected for operation at higher pressure, up to 2757 kPa, and mass flow rate, up to 400 g/s. This replaces the previous Tuthill PD plus 3206 blower and loop limited to 2067 kPa (300 psi) and 100 g/s. The resistively heated test piece is comprised of 7 electric heaters with embedded thermocouples. The plant design for the Mo100 to Mo99 targets requires sharp bends and geometry changes in themore » helium flow tube immediately before and after the target. An idealized fully developed flow configuration with straight entry and exit will be tested and compared with an option that employs rectangular tubing to make the bend at a radius consistent with and practical for the actual plant design. The current plant design, with circular tubing and a sudden contraction to rectangular just prior to target entrance, will also be tested. This requires some modification of the test piece, as described in the report.« less

Numerical Modeling of the Transient Chilldown Process of a Cryogenic Propellant Transfer Line

NASA Technical Reports Server (NTRS)

Hartwig, Jason; Vera, Jerry

2015-01-01

Before cryogenic fuel depots can be fully realized, efficient methods with which to chill down the spacecraft transfer line and receiver tank are required. This paper presents numerical modeling of the chilldown of a liquid hydrogen tank-to-tank propellant transfer line using the Generalized Fluid System Simulation Program (GFSSP). To compare with data from recently concluded turbulent LH2 chill down experiments, seven different cases were run across a range of inlet liquid temperatures and mass flow rates. Both trickle and pulse chill down methods were simulated. The GFSSP model qualitatively matches external skin mounted temperature readings, but large differences are shown between measured and predicted internal stream temperatures. Discrepancies are attributed to the simplified model correlation used to compute two-phase flow boiling heat transfer. Flow visualization from testing shows that the initial bottoming out of skin mounted sensors corresponds to annular flow, but that considerable time is required for the stream sensor to achieve steady state as the system moves through annular, churn, and bubbly flow. The GFSSP model does adequately well in tracking trends in the data but further work is needed to refine the two-phase flow modeling to better match observed test data.

Knowledge Transformation in the United States Air Force Civil Engineer Career Field: A System Dynamics Approach

DTIC Science & Technology

2010-03-01

Review and recommend or approve contracts and cost estimates. Compute load and grade requirements, water flow rates , and material stress factors to...classified into one of ten standard behavioral categories. While the exact rate and value of the behavior may vary, the underlying infrastructure they...it at some rate Y. However, if the same individual increases their knowledge to X*2, retaining that level of knowledge will be more difficult

Identification of aerodynamic models for maneuvering aircraft

NASA Technical Reports Server (NTRS)

Chin, Suei; Lan, C. Edward

1990-01-01

Due to the requirement of increased performance and maneuverability, the flight envelope of a modern fighter is frequently extended to the high angle-of-attack regime. Vehicles maneuvering in this regime are subjected to nonlinear aerodynamic loads. The nonlinearities are due mainly to three-dimensional separated flow and concentrated vortex flow that occur at large angles of attack. Accurate prediction of these nonlinear airloads is of great importance in the analysis of a vehicle's flight motion and in the design of its flight control system. A satisfactory evaluation of the performance envelope of the aircraft may require a large number of coupled computations, one for each change in initial conditions. To avoid the disadvantage of solving the coupled flow-field equations and aircraft's motion equations, an alternate approach is to use a mathematical modeling to describe the steady and unsteady aerodynamics for the aircraft equations of motion. Aerodynamic forces and moments acting on a rapidly maneuvering aircraft are, in general, nonlinear functions of motion variables, their time rate of change, and the history of maneuvering. A numerical method was developed to analyze the nonlinear and time-dependent aerodynamic response to establish the generalized indicial function in terms of motion variables and their time rates of change.

Direct 3D-printing of cell-laden constructs in microfluidic architectures.

PubMed

Liu, Justin; Hwang, Henry H; Wang, Pengrui; Whang, Grace; Chen, Shaochen

2016-04-21

Microfluidic platforms have greatly benefited the biological and medical fields, however standard practices require a high cost of entry in terms of time and energy. The utilization of three-dimensional (3D) printing technologies has greatly enhanced the ability to iterate and build functional devices with unique functions. However, their inability to fabricate within microfluidic devices greatly increases the cost of producing several different devices to examine different scientific questions. In this work, a variable height micromixer (VHM) is fabricated using projection 3D-printing combined with soft lithography. Theoretical and flow experiments demonstrate that altering the local z-heights of VHM improved mixing at lower flow rates than simple geometries. Mixing of two fluids occurs as low as 320 μL min(-1) in VHM whereas the planar zigzag region requires a flow rate of 2.4 mL min(-1) before full mixing occurred. Following device printing, to further demonstrate the ability of this projection-based method, complex, user-defined cell-laden scaffolds are directly printed inside the VHM. The utilization of this unique ability to produce 3D tissue models within a microfluidic system could offer a unique platform for medical diagnostics and disease modeling.

Ground-Water Contributions to Reservoir Storage and the Effect on Estimates of Firm Yield for Reservoirs in Massachusetts

USGS Publications Warehouse

Archfield, Stacey A.; Carlson, Carl S.

2006-01-01

Potential ground-water contributions to reservoir storage were determined for nine reservoirs in Massachusetts that had shorelines in contact with sand and gravel aquifers. The effect of ground water on firm yield was not only substantial, but furthermore, the firm yield of a reservoir in contact with a sand and gravel aquifer was always greater when the ground-water contribution was included in the water balance. Increases in firm yield ranged from 2 to 113 percent, with a median increase in firm yield of 10 percent. Additionally, the increase in firm yield in two reservoirs was greater than 85 percent. This study identified a set of equations that are based on an analytical solution to the ground-water-flow equation for the case of one-dimensional flow in a finite-width aquifer bounded by a linear surface-water feature such as a stream. These equations, which require only five input variables, were incorporated into an existing firm-yield-estimator (FYE) model, and the potential effect of ground water on firm yield was evaluated. To apply the FYE model to a reservoir in Massachusetts, the model requires that the drainage area to the reservoir be clearly defined and that some surface water flows into the reservoir. For surface-water-body shapes having a more realistic representation of a reservoir shoreline than a stream, a comparison of ground-water-flow rates simulated by the ground-water equations with flow rates simulated by a two-dimensional, finite-difference ground-water-flow model indicate that the agreement between the simulated flow rates is within ?10 percent when the ratio of the distance from the reservoir shoreline to the aquifer boundary to the length of shoreline in contact with the aquifer is between values of 0.5 and 3.5. Idealized reservoir-aquifer systems were assumed to verify that the ground-water-flow equations were implemented correctly into the existing FYE model; however, the modified FYE model has not been validated through a comparison of simulated and observed data. A comparison of simulated and observed reservoir water levels would further define limitations to the applicability of the ground-water-flow equations to reservoirs in Massachusetts whose shorelines are in contact with a sand and gravel aquifer.

Suppression of Thermal Emission from Exhaust Components Using an Integrated Approach

DTIC Science & Technology

2002-08-01

design model must, as a minimum, include an accurate estimate of space required for the exhaust , backpressure to the engine , system weight, gas species...hot flovw testing. The virtual design model provides an estimate of space required for: tih exhaust , backiressure to the engine ., svsie:. weigar. gas...either be the engine for the exhaust system or is capable of providing more than the required mass flow rate and enough gas temperature margins so that

Unsteady flow over a decelerating rotating sphere

NASA Astrophysics Data System (ADS)

Turkyilmazoglu, M.

2018-03-01

Unsteady flow analysis induced by a decelerating rotating sphere is the main concern of this paper. A revolving sphere in a still fluid is supposed to slow down at an angular velocity rate that is inversely proportional to time. The governing partial differential equations of motion are scaled in accordance with the literature, reducing to the well-documented von Kármán equations in the special circumstance near the pole. Both numerical and perturbation approaches are pursued to identify the velocity fields, shear stresses, and suction velocity far above the sphere. It is detected that an induced flow surrounding the sphere acts accordingly to adapt to the motion of the sphere up to some critical unsteadiness parameters at certain latitudes. Afterward, the decay rate of rotation ceases such that the flow at the remaining azimuths starts revolving freely. At a critical unsteadiness parameter corresponding to s = -0.681, the decelerating sphere rotates freely and requires no more torque. At a value of s exactly matching the rotating disk flow at the pole identified in the literature, the entire flow field around the sphere starts revolving faster than the disk itself. Increasing values of -s almost diminish the radial outflow. This results in jet flows in both the latitudinal and meridional directions, concentrated near the wall region. The presented mean flow results will be useful for analyzing the instability features of the flow, whether of a convective or absolute nature.

Dispersion of a Nanoliter Bolus in Microfluidic Co-Flow.

PubMed

Conway, A J; Saadi, W M; Sinatra, F L; Kowalski, G; Larson, D; Fiering, J

2014-03-01

Microfluidic systems enable reactions and assays on the scale of nanoliters. However, at this scale nonuniformities in sample delivery become significant. To determine the fundamental minimum sample volume required for a particular device, a detailed understanding of mass transport is required. Co-flowing laminar streams are widely used in many devices, but typically only in the steady-state. Because establishing the co-flow steady-state consumes excess sample volume and time, there is a benefit to operating devices in the transient state, which predominates as the volume of the co-flow reactor decreases. Analysis of the co-flow transient has been neglected thus far. In this work we describe the fabrication of a pneumatically controlled microfluidic injector constructed to inject a discrete 50nL bolus into one side of a two-stream co-flow reactor. Using dye for image analysis, injections were performed at a range of flow rates from 0.5-10μL/min, and for comparison we collected the co-flow steady-state data for this range. The results of the image analysis were also compared against theory and simulations for device validation. For evaluation, we established a metric that indicates how well the mass distribution in the bolus injection approximates steady-state co-flow. Using such analysis, transient-state injections can approximate steady-state conditions within predefined errors, allowing straight forward measurements to be performed with reduced reagent consumption.

On the efficiency of jet production in FR II radio galaxies and quasars

NASA Astrophysics Data System (ADS)

Rusinek, Katarzyna; Sikora, Marek; Kozieł-Wierzbowska, Dorota; Godfrey, Leith

2017-04-01

Jet powers in many radio galaxies with extended radio structures appear to exceed their associated accretion luminosities. In systems with very low accretion rates, this is likely due to the very low accretion luminosities resulting from radiatively inefficient accretion flows. In systems with high accretion rates, the accretion flows are expected to be radiatively efficient, and the production of such powerful jets may require an accretion scenario, which involves magnetically arrested discs (MADs). However, numerical simulations of the MAD scenario indicate that jet production efficiency is large only for geometrically thick accretion flows and scales roughly with (H/R)2, where H is the disc height and R is the distance from the black hole. Using samples of FR II radio galaxies and quasars accreting at moderate accretion rates, we show that their jets are much more powerful than predicted by the MAD scenario. We discuss possible origins of this discrepancy, suggesting that it can be related to approximations adopted in magnetohydrodynamic simulations to treat optically thick accretion flow within the MAD zone, or may indicate that accretion discs are geometrically thicker than the standard theory predicts.

Improvement of oxygen transfer coefficient during Penicillium canescens culture. Influence of turbine design, agitation speed, and air flow rate on xylanase production.

PubMed

Gaspar, A; Strodiot, L; Thonart, P

1998-01-01

To improve xylanase productivity from Penicillium canescens 10-10c culture, an optimization of oxygen supply is required. Because the strain is sensitive to shear forces, leading to lower xylanase productivity as to morphological alteration, vigorous mixing is not desired. The influence of turbine design, agitation speed, and air flow rate on K1a (global mass transfer coefficient, h(-1)) and enzyme production is discussed. K1a values increased with agitation speed and air flow rate, whatever the impeller, in our assay conditions. Agitation had more influence on K1a values than air flow, when a disk-mounted blade's impeller (DT) is used; an opposite result was obtained with a hub-mounted pitched blade's impeller (PBT). Xylanase production appeared as a function of specific power (W/m3), and an optimum was found in 20 and 100 L STRs fitted with DT impellers. On the other hand, the use of a hub-mounted pitched blade impeller (PBT8), instead of a disk-mounted blade impeller (DT4), reduced the lag time of hemicellulase production and increased xylanase productivity 1.3-fold.

Unsteady numerical analysis of solid-liquid two-phase flow in stirred tank with double helical ribbon impeller

NASA Astrophysics Data System (ADS)

Bai, He; Chen, Xiangshan; Zhao, Guangyu; Xiao, Chenglei; Li, Chen; Zhong, Cheng; Chen, Yu

2017-08-01

In order to enhance the mixing process of soil contaminated by oil and water, one kind of double helical ribbon (DHR) impeller was developed. In this study, the unsteady simulation analysis of solid-liquid two-phase flow in stirring tank with DHR impeller was conducted by the the computational fluid dynamics and the multi-reference frame (MRF) method. It was found that at 0-3.0 s stage, the rate of liquid was greater than the rate of solid particles, while the power consumption was 5-6 times more than the smooth operation. The rates of the liquid and the solid particles were almost the same, and the required power was 32 KW at t > 3.0 s. The flow of the solid particles in the tank was a typical axial circle flow, and the dispersed sequence of the solid that was accumulated at the bottom of the tank was: the bottom loop region, the annular region near the wall of the groove and finally the area near axial center. The results show that the DHR impeller was suitable for the mixing of liquid-solid two-phase.

Impact of membrane lung surface area and blood flow on extracorporeal CO2 removal during severe respiratory acidosis.

PubMed

Karagiannidis, Christian; Strassmann, Stephan; Brodie, Daniel; Ritter, Philine; Larsson, Anders; Borchardt, Ralf; Windisch, Wolfram

2017-12-01

Veno-venous extracorporeal CO 2 removal (vv-ECCO 2 R) is increasingly being used in the setting of acute respiratory failure. Blood flow rates through the device range from 200 ml/min to more than 1500 ml/min, and the membrane surface areas range from 0.35 to 1.3 m 2 . The present study in an animal model with similar CO 2 production as an adult patient was aimed at determining the optimal membrane lung surface area and technical requirements for successful vv-ECCO 2 R. Four different membrane lungs, with varying lung surface areas of 0.4, 0.8, 1.0, and 1.3m 2 were used to perform vv-ECCO 2 R in seven anesthetized, mechanically ventilated, pigs with experimentally induced severe respiratory acidosis (pH 7.0-7.1) using a 20Fr double-lumen catheter with a sweep gas flow rate of 8 L/min. During each experiment, the blood flow was increased stepwise from 250 to 1000 ml/min. Amelioration of severe respiratory acidosis was only feasible when blood flow rates from 750 to 1000 ml/min were used with a membrane lung surface area of at least 0.8 m 2 . Maximal CO 2 elimination was 150.8 ml/min, with pH increasing from 7.01 to 7.30 (blood flow 1000 ml/min; membrane lung 1.3 m 2 ). The membrane lung with a surface of 0.4 m 2 allowed a maximum CO 2 elimination rate of 71.7 mL/min, which did not result in the normalization of pH, even with a blood flow rate of 1000 ml/min. Also of note, an increase of the surface area above 1.0 m 2 did not result in substantially higher CO 2 elimination rates. The pressure drop across the oxygenator was considerably lower (<10 mmHg) in the largest membrane lung, whereas the smallest revealed a pressure drop of more than 50 mmHg with 1000 ml blood flow/min. In this porcine model, vv-ECCO 2 R was most effective when using blood flow rates ranging between 750 and 1000 ml/min, with a membrane lung surface of at least 0.8 m 2 . In contrast, low blood flow rates (250-500 ml/min) were not sufficient to completely correct severe respiratory acidosis, irrespective of the surface area of the membrane lung being used. The converse was also true, low surface membrane lungs (0.4 m 2 ) were not capable of completely correcting severe respiratory acidosis across the range of blood flows used in this study.

Determination of Flood Discharges in Rivers as a Prerequisite for Calculating Rates of Geomorphic Change in Drainage Basins During Extreme Events

NASA Astrophysics Data System (ADS)

Smith, J. D.; Kean, J. W.

2003-12-01

Accurate empirical determination of river discharge during an extreme event is very difficult even at a gage site. Moreover, the procurement of extreme flow measurements at many locations in an ungaged drainage basin often is necessary to relate the surface-water flow in the drainage network during a flood to the spatial distribution of intense rainfall. Consequently, paleo-hydrologic methods have to be employed to estimate peak discharges. These methods, however, require the application of some type of flow model. Often the flow models used with paleo-hydrologic data are over simplified and embody low-flow or extrapolated roughness coefficients that are inappropriate for the high flow of interest and that substantially reduce the reliability of the estimated discharge. Models that permit calculation of flow resistance from measured or calculated pre-flood, post-flood, or evolving channel and floodplain geometries and roughnesses can yield the most accurate results for these extreme situations. We have developed a procedure for directly calculating flow discharge as a function of stage in reaches a few tens of river widths in length. The foundation for this approach is a set of algorithms that permits computation of the form drag on topographic elements and woody vegetation. Its application requires an initial survey of the channel and floodplain topography and roughness. The method can be used either with stage determined from a set of pressure gages distributed throughout a drainage basin to monitor discharge in a drainage network or with paleo-hydrologic data to determine discharge from extreme events. Currently, our method of determining discharge from stage is being tested at various sites in the drainage basin of the Whitewater River, Kansas. Two of these sites are just downstream of USGS gages, and a third is a short distance downstream from the outlet pipe of a man-made lake. These tests are for a full range of hydrologic conditions in order to demonstrate that the model-based method for converting stage to discharge can be employed with confidence (1) in ungaged drainage basins where a large number of discharge measurements are required for hydrologic research, (2) at locations where rated USGS stage gages are too expensive, (3) near the sites of USGS stage gages for floods during which the discharge exceeds those for which the gage has been rated, and (4) for situations where paleo-flood methods have to be used to obtain a peak discharge. Model calculated rating curves are compared to measured ones for one of the USGS gage sites. Model calculations also are used to show that Manning's and other friction coefficients are functions of stage at this site. An approach such as the one described here is essential for the quantitative investigation of fluvial geomorphic processes caused by very large floods.

Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

PubMed

Karagiannidis, Christian; Kampe, Kristin Aufm; Sipmann, Fernando Suarez; Larsson, Anders; Hedenstierna, Goran; Windisch, Wolfram; Mueller, Thomas

2014-06-17

While non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH <7.20) still need intubation. Extracorporeal veno-venous CO2 removal (ECCO2R) could prove to be an alternative. The present animal study tested in a systematic fashion technical requirements for successful ECCO2R in terms of cannula size, blood and sweep gas flow. ECCO2R with a 0.98 m(2) surface oxygenator was performed in six acidotic (pH <7.20) pigs using either a 14.5 French (Fr) or a 19Fr catheter, with sweep gas flow rates of 8 and 16 L/minute, respectively. During each experiment the blood flow was incrementally increased to a maximum of 400 mL/minute (14.5Fr catheter) and 1000 mL/minute (19Fr catheter). Amelioration of severe respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH. Veno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

In-situ temperature-controllable shear flow device for neutron scattering measurement--an example of aligned bicellar mixtures.

PubMed

Xia, Yan; Li, Ming; Kučerka, Norbert; Li, Shutao; Nieh, Mu-Ping

2015-02-01

We have designed and constructed a temperature-controllable shear flow cell for in-situ study on flow alignable systems. The device has been tested in the neutron diffraction and has the potential to be applied in the small angle neutron scattering configuration to characterize the nanostructures of the materials under flow. The required sample amount is as small as 1 ml. The shear rate on the sample is controlled by the flow rate produced by an external pump and can potentially vary from 0.11 to 3.8 × 10(5) s(-1). Both unidirectional and oscillational flows are achievable by the setting of the pump. The instrument is validated by using a lipid bicellar mixture, which yields non-alignable nanodisc-like bicelles at low T and shear-alignable membranes at high T. Using the shear cell, the bicellar membranes can be aligned at 31 °C under the flow with a shear rate of 11.11 s(-1). Multiple high-order Bragg peaks are observed and the full width at half maximum of the "rocking curve" around the Bragg's condition is found to be 3.5°-4.1°. It is noteworthy that a portion of the membranes remains aligned even after the flow stops. Detailed and comprehensive intensity correction for the rocking curve has been derived based on the finite rectangular sample geometry and the absorption of the neutrons as a function of sample angle [See supplementary material at http://dx.doi.org/10.1063/1.4908165 for the detailed derivation of the absorption correction]. The device offers a new capability to study the conformational or orientational anisotropy of the solvated macromolecules or aggregates induced by the hydrodynamic interaction in a flow field.

The Effect of Acoustic Disturbances on the Operation of the Space Shuttle Main Engine Fuel Flowmeter

NASA Technical Reports Server (NTRS)

Marcu, Bogdan; Szabo, Roland; Dorney, Dan; Zoladz, Tom

2007-01-01

The Space Shuttle Main Engine (SSME) uses a turbine fuel flowmeter (FFM) in its Low Pressure Fuel Duct (LPFD) to measure liquid hydrogen flowrates during engine operation. The flowmeter is required to provide accurate and robust measurements of flow rates ranging from 10000 to 18000 GPM in an environment contaminated by duct vibration and duct internal acoustic disturbances. Errors exceeding 0.5% can have a significant impact on engine operation and mission completion. The accuracy of each sensor is monitored during hot-fire engine tests on the ground. Flow meters which do not meet requirements are not flown. Among other parameters, the device is screened for a specific behavior in which a small shift in the flow rate reading is registered during a period in which the actual fuel flow as measured by a facility meter does not change. Such behavior has been observed over the years for specific builds of the FFM and must be avoided or limited in magnitude in flight. Various analyses of the recorded data have been made prior to this report in an effort to understand the cause of the phenomenon; however, no conclusive cause for the shift in the instrument behavior has been found. The present report proposes an explanation of the phenomenon based on interactions between acoustic pressure disturbances in the duct and the wakes produced by the FFM flow straightener. Physical insight into the effects of acoustic plane wave disturbances was obtained using a simple analytical model. Based on that model, a series of three-dimensional unsteady viscous flow computational fluid dynamics (CFD) simulations were performed using the MSFC PHANTOM turbomachinery code. The code was customized to allow the FFM rotor speed to change at every time step according to the instantaneous fluid forces on the rotor, that, in turn, are affected by acoustic plane pressure waves propagating through the device. The results of the simulations show the variation in the rotation rate of the flowmeter due to the interaction of the flow straightener wakes and the upstream propagating acoustic waves. A detailed analysis of the acoustic disturbance effects is presented along with an assessment of the impact on measurement accuracy.

The cost of energy from utility-owned solar electric systems. A required revenue methodology for ERDA/EPRI evaluations

NASA Technical Reports Server (NTRS)

1976-01-01

This methodology calculates the electric energy busbar cost from a utility-owned solar electric system. This approach is applicable to both publicly- and privately-owned utilities. Busbar cost represents the minimum price per unit of energy consistent with producing system-resultant revenues equal to the sum of system-resultant costs. This equality is expressed in present value terms, where the discount rate used reflects the rate of return required on invested capital. Major input variables describe the output capabilities and capital cost of the energy system, the cash flows required for system operation amd maintenance, and the financial structure and tax environment of the utility.

Effect of warming and flow rate conditions of blood warmers on red blood cell integrity.

PubMed

Poder, T G; Pruneau, D; Dorval, J; Thibault, L; Fisette, J-F; Bédard, S K; Jacques, A; Beauregard, P

2016-11-01

Fluid warmers are routinely used to reduce the risk of hypothermia and cardiac complications associated with the infusion of cold blood products. However, warming blood products could generate haemolysis. This study was undertaken to compare the impact of temperature of blood warmers on the per cent haemolysis of packed red blood cells (RBCs) heated at different flow rates as well as non-flow conditions. Infusion warmers used were calibrated at 41·5°C ± 0·5°C and 37·5°C ± 0·5°C. Cold RBC units stored at 4°C in AS-3 (n = 30), aged 30-39 days old, were divided into half units before being allocated under two different scenarios (i.e. infusion pump or syringe). Blood warmers were effective to warm cold RBCs to 37·5°C or 41·5°C when used in conjunction with an infusion pump at flow rate up to 600 ml/h. However, when the warmed blood was held in a syringe for various periods of time, such as may occur in neonatal transfusions, the final temperature was below the expected requirements with measurement as low as 33·1°C. Increasing the flow with an infusion pump increased haemolysis in RBCs from 0·2% to up to 2·1% at a flow rate of 600 ml/h regardless of the warming device used (P < 0·05). No relevant increase of haemolysis was observed using a syringe. The use of a blood warmer adjusted to 41·5°C is probably the best choice for reducing the risk of hypothermia for the patient without generating haemolysis. However, we should be cautious with the use of an infusion pump for RBC transfusion, particularly at high flow rates. © 2016 International Society of Blood Transfusion.

Oxygen Flow Rate Requirements of Critically Injured Patients

DTIC Science & Technology

2015-04-08

2.0 BACKGROUND Supplemental oxygen is required to correct hypoxemia and is often used to augment tissue oxygen delivery following hemorrhagic ...least 6 months after enrollment to determine mortality status. 3.4 Outcome Measurements The primary outcomes were the proportion of subjects...and 53/204 (26%) with hemorrhagic shock (systolic blood pressure (SBP) ៊ or blood transfusion). There were 33/142 (23%) patients with an indication

Chemical Reactions in Turbulent Mixing Flows

DTIC Science & Technology

1989-10-15

response, following the program control actuation. 3 in 2 vs. roughly the 8in2 required for the M1 = 1.5 (high speed stream Mach number) flow planned for...Papamoschou & Roshko (1988) as the compressibility-effect parameter, on the growth rate of the mixing layers was studied. In a finite thickness...attained is at present controversial; an issue that will have to be resolved both theoretically as well as with the planned for experiments. A sample plot

Geologic, geochemical rock mechanics and hydrologic characteristics of candidate repository horizons

NASA Astrophysics Data System (ADS)

Long, P. E.; Apted, M. J.; Spane, F. A., Jr.; Kim, K.

1982-09-01

The feasibility of constructing a nuclear waste repository in basalt (NWRB) on the Hanford Site is determined. Studies conducted indicate feasibility and performance requirements are within a significant safety margin. The two most promising candidate repository horizons for an NWRB are the middle Sentinel Bluffs and the Umtanum flows. Both of these flows are laterally continuous and have thicknesses of competent rock adequate to accommodate a repository. Significant geologic differences between the two flows are their depth, total thickness, and variability of flow top thickness. These differences are considered in selection of one of the two flows for breakout from an exploratory shaft. The geochemical characteristics of both the middle Sentinel Bluffs flow and the Umtanum flow favor long term isolation of radionuclides by providing an environment in which canister corrosion rates and solubility of many radionuclide bearing solids is relatively low.

Complex Greenland outlet glacier flow captured

PubMed Central

Aschwanden, Andy; Fahnestock, Mark A.; Truffer, Martin

2016-01-01

The Greenland Ice Sheet is losing mass at an accelerating rate due to increased surface melt and flow acceleration in outlet glaciers. Quantifying future dynamic contributions to sea level requires accurate portrayal of outlet glaciers in ice sheet simulations, but to date poor knowledge of subglacial topography and limited model resolution have prevented reproduction of complex spatial patterns of outlet flow. Here we combine a high-resolution ice-sheet model coupled to uniformly applied models of subglacial hydrology and basal sliding, and a new subglacial topography data set to simulate the flow of the Greenland Ice Sheet. Flow patterns of many outlet glaciers are well captured, illustrating fundamental commonalities in outlet glacier flow and highlighting the importance of efforts to map subglacial topography. Success in reproducing present day flow patterns shows the potential for prognostic modelling of ice sheets without the need for spatially varying parameters with uncertain time evolution. PMID:26830316

Analysis of Clinicians' Perceptual Cough Evaluation.

PubMed

Laciuga, Helena; Brandimore, Alexandra E; Troche, Michelle S; Hegland, Karen W

2016-08-01

This study examined the relationships between subjective descriptors and objective airflow measures of cough. We hypothesized that coughs with specific airflow characteristics would share common subjective perceptual descriptions. Thirty clinicians (speech-language pathologists, otolaryngologists, and neurologists) perceptually evaluated ten cough audio samples with specific airflow characteristics determined by peak expiratory flow rate, cough expired volume, cough duration, and number of coughs in the cough epoch. Participants rated coughs by strength, duration, quality, quantity, and overall potential effectiveness for airway protection. Perception of cough strength and effectiveness was determined by the combination of presence of pre-expulsive compression phase, short peak expiratory airflow rate rise time, high peak expiratory flow rates, and high cough volume acceleration. Perception of cough abnormality was defined predominantly by descriptors of breathiness and strain. Breathiness was characteristic for coughs with either absent compression phases and relatively high expiratory airflow rates or coughs with significantly low expired volumes and reduced peak flow rates. In contrast, excessive strain was associated with prolonged compression phases and low expiratory airflow rates or the absence of compression phase with high peak expiratory rates. The study participants reached greatest agreement in distinguishing between single and multiple coughs. Their assessment of cough strength and effectiveness was less consistent. Finally, the least agreement was shown in determining the quality categories. Modifications of cough airflow can influence perceptual cough evaluation outcomes. However, the inconsistency of cough ratings among our participants suggests that a uniform cough rating system is required.

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

PubMed

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

2011-01-01

To investigate lower urinary tract symptoms (LUTS) and voiding function in a cohort of hyperthyroid women. The autonomic nervous system (ANS) imbalance has been thought to cause LUTS in hyperthyroidism. Between January 2008 and December 2008, 65 newly diagnosed, untreated female hyperthyroid patients were enrolled in this study. Another 62 age-matched healthy women were enrolled as a control group. Demographics, LUTS, urinary flow rates, hyperthyroid symptoms, and serum levels of thyroid hormones were recorded before and after the medical treatment for hyperthyroidism. Compared with the control group, the hyperthyroid patients had a higher mean symptom score of frequency (1.15 ± 1.75 vs 0.31 ± 1.05, P = .01), incomplete emptying (0.91 ± 1.47 vs 0.29 ± 1.12, P = .02), straining (1.05 ± 0.85 vs 0.27 ± 0.51, P <.01), voiding symptoms (3.05 ± 3.28 vs 1.06 ± 2.63, P <.01), and total symptoms (5.88 ± 6.17 vs 2.76 ± 4.65, P <.01). Fifty-three (81.5%) of them had an IPSS of <8, while only 12 (18.5%) had an International Prostate Symptom Score (IPSS) of ≥8. Hyperthyroid women demonstrated a lower mean peak flow rate (25.0 ± 5.3 vs 28.6 ± 6.1 mL/s, P = .02). After treatment, both LUTS and flow rates improved significantly. The severity of LUTS was associated with neither serum levels of thyroid hormone nor other hyperthyroid symptoms. Hyperthyroid women have worse LUTS and lower peak flow rates than healthy controls. However, the severity of LUTS is only mild (IPSS <8) in the majority, and only 18.5% have moderate-to-severe LUTS. Both LUTS and flow rates improve after the treatment for hyperthyroidism. The exact mechanisms of LUTS and/or lower urinary tract dysfunction in hyperthyroidism require further investigation. Copyright © 2011 Elsevier Inc. All rights reserved.

VISCOUS CHARACTERICTICS ANALYSIS

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1994-01-01

Current investigations of the hydrogen-fueled supersonic combustion ramjet engine have delineated several technological problem areas. One area, the analysis of the injection, turbulent mixing, and combusiton of hydrogen, requires the accurate calculation of the supersonic combustion flow fields. This calculation has proven difficult because of an interesting phenomena which makes possible the transition from supersonic to subsonic flow in the combustion field, due to the temperature transitions which occur in the flow field. This computer program was developed to use viscous characteristics theory to analyze supersonic combustion flow fields with imbedded subsonic regions. Intended to be used as a practical design tool for two-dimensional and axisymmetric supersonic combustor development, this program has proven useful in the analysis of such problems as determining the flow field of a single underexpanded hydrogen jet, the internal flow of a gas sampling probe, the effects of fuel-injector strut shape, and the effects of changes in combustor configuration. Both combustion and diffusive effects can significantly alter the wave pattern in a supersonic field and generate significant pressure gradients in both the axial and radial directions. The induced pressure, in turn, substantially influences the ignition delay and reaction times as well as the velocity distribution. To accurately analyze the flow fields, the effects of finite rate chemistry, mixing, and wave propagation must be properly linked to one another. The viscous characteristics theory has been used in the past to describe flows that are purely supersonic; however, the interacting pressure effects in the combustor often allow for the development of shock waves and imbedded subsonic regions. Numerical investigation of these transonic situations has required the development of a new viscous characteristics procedure which is valid within the subsonic region and can be coupled with the standard viscous characteristics procedure in the supersonic region. The basic governing equations used are the 'viscous-inviscid' equations, similar to those employed in higher-order boundary layer analyses, with finite rate chemistry terms included. In addition, the Rankine-Hugoniot and Prandtl-Meyer relations are used to compute shock and expansion conditions. The program can handle up to 20 simultaneous shock waves. Chemistry terms are computed for a 7-species 8-mechanism hydrogen-air reaction scheme. The user input consists of a physical description of the combustor and flow determination parameters. Output includes detail flow parameter values at selected points within the flow field. This computer program is written in FORTRAN IV for batch execution and has been implemented on a CDC CYBER 175 with a central memory requirement of approximately 114K (octal) of 60 bit words. The program was developed in 1978.

Linking fish tolerance to water quality criteria for the assessment of environmental flows: A practical method for streamflow regulation and pollution control.

PubMed

Zhao, Changsen; Yang, Shengtian; Liu, Junguo; Liu, Changming; Hao, Fanghua; Wang, Zhonggen; Zhang, Huitong; Song, Jinxi; Mitrovic, Simon M; Lim, Richard P

2018-05-15

The survival of aquatic biota in stream ecosystems depends on both water quantity and quality, and is particularly susceptible to degraded water quality in regulated rivers. Maintenance of environmental flows (e-flows) for aquatic biota with optimum water quantity and quality is essential for sustainable ecosystem services, especially in developing regions with insufficient stream monitoring of hydrology, water quality and aquatic biota. Few e-flow methods are available that closely link aquatic biota tolerances to pollutant concentrations in a simple and practical manner. In this paper a new method was proposed to assess e-flows that aimed to satisfy the requirements of aquatic biota for both the quantity and quality of the streamflow by linking fish tolerances to water quality criteria, or the allowable concentration of pollutants. For better operation of water projects and control of pollutants discharged into streams, this paper presented two coefficients for streamflow adjustment and pollutant control. Assessment of e-flows in the Wei River, the largest tributary of the Yellow River, shows that streamflow in dry seasons failed to meet e-flow requirements. Pollutant influx exerted a large pressure on the aquatic ecosystem, with pollutant concentrations much higher than that of the fish tolerance thresholds. We found that both flow velocity and water temperature exerted great influences on the pollutant degradation rate. Flow velocity had a much greater influence on pollutant degradation than did the standard deviation of flow velocity. This study provides new methods to closely link the tolerance of aquatic biota to water quality criteria for e-flow assessment. The recommended coefficients for streamflow adjustment and pollutant control, to dynamically regulate streamflow and control pollutant discharge, are helpful for river management and ecosystems rehabilitation. The relatively low data requirement also makes the method easy to use efficiently in developing regions, and thus this study has significant implications for managing flows in polluted and regulated rivers worldwide. Copyright © 2018. Published by Elsevier Ltd.

Removing Constraints on the Biomass Production of Freshwater Macroalgae by Manipulating Water Exchange to Manage Nutrient Flux

PubMed Central

Cole, Andrew J.; de Nys, Rocky; Paul, Nicholas A.

2014-01-01

Freshwater macroalgae represent a largely overlooked group of phototrophic organisms that could play an important role within an industrial ecology context in both utilising waste nutrients and water and supplying biomass for animal feeds and renewable chemicals and fuels. This study used water from the intensive aquaculture of freshwater fish (Barramundi) to examine how the biomass production rate and protein content of the freshwater macroalga Oedogonium responds to increasing the flux of nutrients and carbon, by either increasing water exchange rates or through the addition of supplementary nitrogen and CO2. Biomass production rates were highest at low flow rates (0.1–1 vol.day−1) using raw pond water. The addition of CO2 to cultures increased biomass production rates by between 2 and 25% with this effect strongest at low water exchange rates. Paradoxically, the addition of nitrogen to cultures decreased productivity, especially at low water exchange rates. The optimal culture of Oedogonium occurred at flow rates of between 0.5–1 vol.day−1, where uptake rates peaked at 1.09 g.m−2.day−1 for nitrogen and 0.13 g.m−2.day−1 for phosphorous. At these flow rates Oedogonium biomass had uptake efficiencies of 75.2% for nitrogen and 22.1% for phosphorous. In this study a nitrogen flux of 1.45 g.m−2.day−1 and a phosphorous flux of 0.6 g.m−2.day−1 was the minimum required to maintain the growth of Oedogonium at 16–17 g DW.m−2.day−1 and a crude protein content of 25%. A simple model of minimum inputs shows that for every gram of dry weight biomass production (g DW.m−2.day−1), Oedogonium requires 0.09 g.m−2.day−1 of nitrogen and 0.04 g.m−2.day−1 of phosphorous to maintain growth without nutrient limitation whilst simultaneously maintaining a high-nutrient uptake rate and efficiency. As such the integrated culture of freshwater macroalgae with aquaculture for the purposes of nutrient recovery is a feasible solution for the bioremediation of wastewater and the supply of a protein resource. PMID:25000501

Removing constraints on the biomass production of freshwater macroalgae by manipulating water exchange to manage nutrient flux.

PubMed

Cole, Andrew J; de Nys, Rocky; Paul, Nicholas A

2014-01-01

Freshwater macroalgae represent a largely overlooked group of phototrophic organisms that could play an important role within an industrial ecology context in both utilising waste nutrients and water and supplying biomass for animal feeds and renewable chemicals and fuels. This study used water from the intensive aquaculture of freshwater fish (Barramundi) to examine how the biomass production rate and protein content of the freshwater macroalga Oedogonium responds to increasing the flux of nutrients and carbon, by either increasing water exchange rates or through the addition of supplementary nitrogen and CO2. Biomass production rates were highest at low flow rates (0.1-1 vol.day-1) using raw pond water. The addition of CO2 to cultures increased biomass production rates by between 2 and 25% with this effect strongest at low water exchange rates. Paradoxically, the addition of nitrogen to cultures decreased productivity, especially at low water exchange rates. The optimal culture of Oedogonium occurred at flow rates of between 0.5-1 vol.day-1, where uptake rates peaked at 1.09 g.m-2.day-1 for nitrogen and 0.13 g.m-2.day-1 for phosphorous. At these flow rates Oedogonium biomass had uptake efficiencies of 75.2% for nitrogen and 22.1% for phosphorous. In this study a nitrogen flux of 1.45 g.m-2.day-1 and a phosphorous flux of 0.6 g.m-2.day-1 was the minimum required to maintain the growth of Oedogonium at 16-17 g DW.m-2.day-1 and a crude protein content of 25%. A simple model of minimum inputs shows that for every gram of dry weight biomass production (g DW.m-2.day-1), Oedogonium requires 0.09 g.m-2.day-1 of nitrogen and 0.04 g.m-2.day-1 of phosphorous to maintain growth without nutrient limitation whilst simultaneously maintaining a high-nutrient uptake rate and efficiency. As such the integrated culture of freshwater macroalgae with aquaculture for the purposes of nutrient recovery is a feasible solution for the bioremediation of wastewater and the supply of a protein resource.

A dryer for rapid response on-line expired gas measurements.

PubMed

Deno, N S; Kamon, E

1979-06-01

A dryer is described for use in on-line breath-by-breath gas analysis systems. The dryer continuously removes water vapor by condensation and controls the sample gas at 2 degrees C dew-point temperature or 5 Torr water vapor partial pressure. It is designed to operate at gas sampling flow rates from 0.5 to 1 1.min-1. The step-response time for the described system including a Beckman LB-2 CO2 analyzer, sampling tubing, and dryer is 120 ms at 1 l.min-1. The time required for gas samples to transport through the dryer is 105 ms at a gas sampling-flow rate of 1 l.min=1.

Coarsening strategies for unstructured multigrid techniques with application to anisotropic problems

NASA Technical Reports Server (NTRS)

Morano, E.; Mavriplis, D. J.; Venkatakrishnan, V.

1995-01-01

Over the years, multigrid has been demonstrated as an efficient technique for solving inviscid flow problems. However, for viscous flows, convergence rates often degrade. This is generally due to the required use of stretched meshes (i.e., the aspect-ratio AR = delta y/delta x is much less than 1) in order to capture the boundary layer near the body. Usual techniques for generating a sequence of grids that produce proper convergence rates on isotopic meshes are not adequate for stretched meshes. This work focuses on the solution of Laplace's equation, discretized through a Galerkin finite-element formulation on unstructured stretched triangular meshes. A coarsening strategy is proposed and results are discussed.

Coarsening Strategies for Unstructured Multigrid Techniques with Application to Anisotropic Problems

NASA Technical Reports Server (NTRS)

Morano, E.; Mavriplis, D. J.; Venkatakrishnan, V.

1996-01-01

Over the years, multigrid has been demonstrated as an efficient technique for solving inviscid flow problems. However, for viscous flows, convergence rates often degrade. This is generally due to the required use of stretched meshes (i.e. the aspect-ratio AR = (delta)y/(delta)x much less than 1) in order to capture the boundary layer near the body. Usual techniques for generating a sequence of grids that produce proper convergence rates on isotropic meshes are not adequate for stretched meshes. This work focuses on the solution of Laplace's equation, discretized through a Galerkin finite-element formulation on unstructured stretched triangular meshes. A coarsening strategy is proposed and results are discussed.

Photochemically Etched Construction Technology Developed for Digital Xenon Feed Systems

NASA Technical Reports Server (NTRS)

Otsap, Ben; Cardin, Joseph; Verhey, Timothy R.; Rawlin, Vincent K.; Mueller, Juergen; Aadlund, Randall; Kay, Robert; Andrews, Michael

2005-01-01

Electric propulsion systems are quickly emerging as attractive options for primary propulsion in low Earth orbit, in geosynchronous orbit, and on interplanetary spacecraft. The driving force behind the acceptance of these systems is the substantial reduction in the propellant mass that can be realized. Unfortunately, system designers are often forced to utilize components designed for chemical propellants in their electric systems. Although functionally acceptable, these relatively large, heavy components are designed for the higher pressures and mass flow rates required by chemical systems. To fully realize the benefits of electric propulsion, researchers must develop components that are optimized for the low flow rates, critical leakage needs, low pressures, and limited budgets of these emerging systems.

Extracorporeal CO2 removal by hemodialysis: in vitro model and feasibility.

PubMed

May, Alexandra G; Sen, Ayan; Cove, Matthew E; Kellum, John A; Federspiel, William J

2017-12-01

Critically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO 2 from the blood, mainly as bicarbonate. In this study, Stewart's approach to acid-base chemistry was used to create a dialysate that would maintain blood pH while removing CO 2 as well as determine the blood and dialysate flow rates necessary to remove clinically relevant CO 2 volumes. Bench studies were performed using a scaled down respiratory hemodialyzer in bovine or porcine blood. The scaling factor for the bench top experiments was 22.5. In vitro dialysate flow rates ranged from 2.2 to 24 mL/min (49.5-540 mL/min scaled up) and blood flow rates were set at 11 and 18.7 mL/min (248-421 mL/min scaled up). Blood inlet CO 2 concentrations were set at 50 and 100 mmHg. Results are reported as scaled up values. The CO 2 removal rate was highest at intermittent hemodialysis blood and dialysate flow rates. At an inlet pCO 2 of 50 mmHg, the CO 2 removal rate increased from 62.6 ± 4.8 to 77.7 ± 3 mL/min when the blood flow rate increased from 248 to 421 mL/min. At an inlet pCO 2 of 100 mmHg, the device was able to remove up to 117.8 ± 3.8 mL/min of CO 2 . None of the test conditions caused the blood pH to decrease, and increases were ≤0.08. When the bench top data is scaled up, the system removes a therapeutic amount of CO 2 standard intermittent hemodialysis flow rates. The zero bicarbonate dialysate did not cause acidosis in the post-dialyzer blood. These results demonstrate that, with further development, respiratory hemodialysis can be a minimally invasive extracorporeal carbon dioxide removal treatment option.

40 CFR 1065.545 - Validation of proportional flow control for batch sampling.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of the estimate, SEE, of the sample flow rate versus the total flow rate. For each test interval, demonstrate that SEE was less than or equal to 3.5% of the mean sample flow rate. (b) For any pair of flow meters, use recorded sample and total flow rates, where total flow rate means the raw exhaust flow rate...

Development, Calibration and Deployment of an Electromagnetic Flowmeter for Cross-Hole Hydrogeologic Experiments

NASA Astrophysics Data System (ADS)

Slovacek, A. E.; Fisher, A. T.; Kirkwood, W.; Wheat, C. G.; Maughan, T.; Gomes, K.

2011-12-01

We developed an autonomous electromagnetic flowmeter as part of a cross-hole hydrogeologic experiment using subseafloor borehole observatories (CORKs) that penetrate into the volcanic ocean crust. The cylindrical flowmeter is adapted from a conventional industrial tool and hardened for use at water depths up to 6000 m. In addition, the electronics were modified with a new power controller, and a data logger and communication board was added to enable data storage and long-term, autonomous use for up to eight years. The flowmeter generates a magnetic field and measures a voltage gradient that is created across the orifice as water moves through it. This kind of tool is ideally suited for use in the deep sea, particularly for measuring hydrothermal fluids emanating from the ocean crust, because it requires no moving parts, places no obstructions along the flow path, gives total flow volume as well as instantaneous flow rate, and is highly accurate across a large dynamic range, including bi-directional flow. This flowmeter was deployed on a CORK wellhead using an adapter and ring clamp system located above a 4-inch ball valve. The ball valve can be opened to permit flow (from an overpressured formation) out of the CORK and into the overlying ocean. A polyvinyl chloride "chimney" positioned vertically above the flowmeter is instrumented with autonomous temperature loggers to permit an additional estimate of fluid flow rates with time, based on heat loss during fluid ascent, and to facilitate fluid sampling. Calibration of the new flowmeter was completed in two stages: tank testing using a pump at flow rates of 0.5 to 1.2 L/s, and by lowering the flowmeter on a wireline at sea at rates equivalent to 0.5 to 5.2 L/s. A cross plot of apparent and reference flow rates obtained during calibration indicates a highly linear instrument response. Comparison of instantaneous (once per minute) and integrated (total flow) data collected during calibration indicates good agreement, although the instantaneous data tended to be noisy because of irregularity of flow (turbulence). The flowmeter was deployed in Summer 2011 on a CORK installed in IODP Hole 1362B, on the eastern flank of the Juan de Fuca ridge. Once the flowmeter was attached to the wellhead, the underlying ball valve was opened, which allowed overpressured fluids from the permeable ocean crust to flow upward and out of the seafloor at 5 to 10 L/s (estimated rate). Changes in formation fluid pressure resulting from this flow are being monitored in four additional CORKs located 310 to 2320 m away from Hole 1362B, which will allow large-scale, directional assessment of formation properties. The flowmeter is recording data for instantaneous flow rate and total flow once per hour, and will be recovered to permit collection and analysis of experimental data during a servicing visit in Summer 2012.

Numerical Investigation of PLIF Gas Seeding for Hypersonic Boundary Layer Flows

NASA Technical Reports Server (NTRS)

Johanson, Craig T.; Danehy, Paul M.

2012-01-01

Numerical simulations of gas-seeding strategies required for planar laser-induced fluorescence (PLIF) in a Mach 10 air flow were performed. The work was performed to understand and quantify adverse effects associated with gas seeding and to compare different flow rates and different types of seed gas. The gas was injected through a slot near the leading edge of a flat plate wedge model used in NASA Langley Research Center's 31- Inch Mach 10 Air Tunnel facility. Nitric oxide, krypton, and iodine gases were simulated at various injection rates. Simulation results showing the deflection of the velocity field for each of the cases are presented. Streamwise distributions of velocity and concentration boundary layer thicknesses as well as vertical distributions of velocity, temperature, and mass distributions are presented for each of the cases. Relative merits of the different seeding strategies are discussed.

Liquid metal enabled pump

PubMed Central

Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O’Mullane, Anthony P.; Abbott, Derek; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2014-01-01

Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

Toxicity studies of a polyurethane rigid foam

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Schneider, J. E.

1977-01-01

Relative toxicity tests were performed on a polyurethane foam containing a trimethylopropane-based polyol and an organophosphate flame retardant. The routine screening procedure involved the exposure of four Swiss albino male mice in a 4.2 liter hemispherical chamber to the products generated by pyrolyzing a 1.00 g sample at a heating rate of 40 deg C/min from 200 to 800 C in the absence of air flow. In addition to the routine screening, experiments were performed with a very rapid rise to 800 C, with nominal 16 and 48 ml/sec air flow and with varying sample rates. No unusual toxicity was observed with either gradual or rapid pyrolysis to 800 C. Convulsions and seizures similar to those previously reported were observed when the materials were essentially flash pyrolyzed at 800 C in the presence of air flow, and the toxicity appeared unusual because of low sample weights required to produce death.

Cosmic ray exposure dating with in situ produced cosmogenic 3He: results from young Hawaiian lava flows

USGS Publications Warehouse

Kurz, M.D.; Colodner, D.; Trull, T.W.; Moore, R.B.; O'Brien, K.

1990-01-01

In an effort to determine the in situ production rate of spallation-produced cosmogenic 3He, and evaluate its use as a surface exposure chronometer, we have measured cosmogenic helium contents in a suite of Hawaiian radiocarbon-dated lava flows. The lava flows, ranging in age from 600 to 13,000 years, were collected from Hualalai and Mauna Loa volcanoes on the island of Hawaii. Because cosmic ray surface-exposure dating requires the complete absence of erosion or soil cover, these lava flows were selected specifically for this purpose. The 3He production rate, measured within olivine phenocrysts, was found to vary significantly, ranging from 47 to 150 atoms g-1 yr-1 (normalized to sea level). Although there is considerable scatter in the data, the samples younger than 10,000 years are well-preserved and exposed, and the production rate variations are therefore not related to erosion or soil cover. Data averaged over the past 2000 years indicate a sea-level 3He production rate of 125 ?? 30 atoms g-1 yr-1, which agrees well with previous estimates. The longer record suggests a minimum in sea level normalized 3He production rate between 2000 and 7000 years (55 ?? 15 atoms g-1 yr-1), as compared to samples younger than 2000 years (125 ?? 30 atoms g-1 yr-1), and those between 7000 and 10,000 years (127 ?? 19 atoms g-1 yr-1). The minimum in production rate is similar in age to that which would be produced by variations in geomagnetic field strength, as indicated by archeomagnetic data. However, the production rate variations (a factor of 2.3 ?? 0.8) are poorly determined due to the large uncertainties in the youngest samples and questions of surface preservation for the older samples. Calculations using the atmospheric production model of O'Brien (1979) [35], and the method of Lal and Peters (1967) [11], predict smaller production rate variations for similar variation in dipole moment (a factor of 1.15-1.65). Because the production rate variations, archeomagnetic data, and theoretical estimates are not well determined at present, the relationship between dipole moment and production rate will require further study. Precise determination of the production rate is an important uncertainty in the surface-exposure technique, but the data demonstrate that it is feasible to date samples as young as 600 years of age providing that there has been no erosion or soil cover. Therefore, the technique will have important applications for volcanology, glacial geology, geomorphology and archaeology. ?? 1990.

Microvascular flow estimation by contrast-assisted ultrasound B-scan and statistical parametric images.

PubMed

Tsui, Po-Hsiang; Yeh, Chih-Kuang; Chang, Chien-Cheng

2009-05-01

The microbubbles destruction/replenishment technique has been previously applied to estimating blood flow in the microcirculation. The rate of increase of the time-intensity curve (TIC) due to microbubbles flowing into the region of interest (ROI), as measured from B-mode images, closely reflects the flow velocity. In previous studies, we proposed a new approach called the time-Nakagami-parameter curve (TNC) obtained from Nakagami images to monitor microbubble replenishment for quantifying the microvascular flow velocity. This study aimed to further explore some effects that may affect the TNC to estimate the microflow, including microbubble concentration, ultrasound transmitting energy, attenuation, intrinsic noise, and tissue clutter. In order to well control each effect production, we applied a typical simulation method to investigate the TIC and TNC. The rates of increase of the TIC and TNC were expressed by the rate constants beta(I) and beta(N), respectively, of a monoexponential model. The results show that beta(N) quantifies the microvascular flow velocity similarly to the conventional beta(I) . Moreover, the measures of beta(I) and beta(N) are not influenced by microbubble concentration, transducer excitation energy, and attenuation effect. Although the effect of intrinsic signals contributed by noise and blood would influence the TNC behavior, the TNC method has a better tolerance of tissue clutter than the TIC does, allowing the presence of some clutter components in the ROI. The results suggest that the TNC method can be used as a complementary tool for the conventional TIC to reduce the wall filter requirements for blood flow measurement in the microcirculation.

Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

DOE PAGES

Liang, David Y.; Tentori, Augusto M.; Dimov, Ivan K.; ...

2011-01-01

Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics ofmore » degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL/s and mean flow rates of approximately 1-1.5 nL/s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.« less

Influence of respiratory muscle work on VO(2) and leg blood flow during submaximal exercise.

PubMed

Wetter, T J; Harms, C A; Nelson, W B; Pegelow, D F; Dempsey, J A

1999-08-01

The work of breathing (W(b)) normally incurred during maximal exercise not only requires substantial cardiac output and O(2) consumption (VO(2)) but also causes vasoconstriction in locomotor muscles and compromises leg blood flow (Q(leg)). We wondered whether the W(b) normally incurred during submaximal exercise would also reduce Q(leg). Therefore, we investigated the effects of changing the W(b) on Q(leg) via thermodilution in 10 healthy trained male cyclists [maximal VO(2) (VO(2 max)) = 59 +/- 9 ml. kg(-1). min(-1)] during repeated bouts of cycle exercise at work rates corresponding to 50 and 75% of VO(2 max). Inspiratory muscle work was 1) reduced 40 +/- 6% via a proportional-assist ventilator, 2) not manipulated (control), or 3) increased 61 +/- 8% by addition of inspiratory resistive loads. Increasing the W(b) during submaximal exercise caused VO(2) to increase; decreasing the W(b) was associated with lower VO(2) (DeltaVO(2) = 0.12 and 0.21 l/min at 50 and 75% of VO(2 max), respectively, for approximately 100% change in W(b)). There were no significant changes in leg vascular resistance (LVR), norepinephrine spillover, arterial pressure, or Q(leg) when W(b) was reduced or increased. Why are LVR, norepinephrine spillover, and Q(leg) influenced by the W(b) at maximal but not submaximal exercise? We postulate that at submaximal work rates and ventilation rates the normal W(b) required makes insufficient demands for VO(2) and cardiac output to require any cardiovascular adjustment and is too small to activate sympathetic vasoconstrictor efferent output. Furthermore, even a 50-70% increase in W(b) during submaximal exercise, as might be encountered in conditions where ventilation rates and/or inspiratory flow resistive forces are higher than normal, also does not elicit changes in LVR or Q(leg).

The influence of underlying topography on lava channel networks and flow behavior (Invited)

NASA Astrophysics Data System (ADS)

Dietterich, H. R.; Cashman, K. V.; Rust, A.

2013-12-01

New high resolution mapping of historical lava flows in Hawai';i reveals complex topographically controlled channel networks. Network morphologies range from distributary systems dominated by branching around local obstacles, to tributary systems constricted by topographic confinement. Because channel networks govern the distribution of lava within the flow, they can dramatically alter the effective volumetric flux, which affects both flow length and advance rate. The influence of flow bifurcations is evidenced by (1) channelized flows from Pu';u ';O';o episodes 1-20 at Kilauea Volcano, where flow front velocities decreased by approximately half each time a flow split, and (2) the length of confined flows, such as the Mauna Loa 1859 flow, which traveled twice as far as the distributary Mauna Loa 1984 flow, despite similar effusion rates and durations. To study the underlying controls on flow bifurcations, we have undertaken a series of analogue experiments with golden syrup (a Newtonian fluid) to better understand the physics of obstacle interaction and its influence on flow behavior and morphology. Controlling the effusion rate and surface slope, we extrude flows onto a surface with a cylindrical or V-shaped obstacle of variable angle. When the flow is sufficiently fast, a stationary wave forms upslope of the obstacle; if the stationary wave is sufficiently high, the flow can overtop, rather than split around, the obstacle. The stationary wave height increases with flow velocity and with the effective obstacle width. Evidence for stationary waves in Hawaiian lava flows comes from both photographs of active flows and waveforms frozen into solidified flows. We have also performed a preliminary set of similar experiments with molten basalt to identify the effect of cooling and investigate flow merging. In these experiments, a stationary wave develops upslope of the obstacle, which allows the surface to cool and thicken. After splitting, the syrup experiments show minimal impact of the split on flow advance, except in cases where the flow is very thin, and surface tension controls the flow behavior. In contrast, the experiments with molten basalt slow markedly, as measured by both flow front and surface velocities. This difference demonstrates the effect of cooling and crust formation on flowing lava. Crust formation also controls the ability of split flows to merge below an obstacle, such that flows can converge only at high flow rates, which limits time for crust formation, and at narrow obstacle angles, which limits the lateral spreading required for convergence. Our experiments qualitatively support theoretical descriptions of crustal controls on flow spreading and levee development, but our poor knowledge of the appropriate parameter values, particularly that of the strength of the viscoelastic crust, prevents a quantitative comparison. These experiments, and our observations from natural systems, have significant implications for predicting lava flow behavior and inform efforts to mitigate flow hazards with diversion barriers.

Influence of vascular network design on gas transfer in lung assist device technology.

PubMed

Bassett, Erik K; Hoganson, David M; Lo, Justin H; Penson, Elliot J N; Vacanti, Joseph P

2011-01-01

Blood oxygenators are vital for the critically ill, but their use is limited to the hospital setting. A portable blood oxygenator or a lung assist device for ambulatory or long-term use would greatly benefit patients with chronic lung disease. In this work, a biomimetic blood oxygenator system was developed which consisted of a microfluidic vascular network covered by a gas permeable silicone membrane. This system was used to determine the influence of key microfluidic parameters-channel size, oxygen exposure length, and blood shear rate-on blood oxygenation and carbon dioxide removal. Total gas transfer increased linearly with flow rate, independent of channel size and oxygen exposure length. On average, CO(2) transfer was 4.3 times higher than oxygen transfer. Blood oxygen saturation was also found to depend on the flow rate per channel but in an inverse manner; oxygenation decreased and approached an asymptote as the flow rate per channel increased. These relationships can be used to optimize future biomimetic vascular networks for specific lung applications: gas transfer for carbon dioxide removal in patients with chronic obstructive pulmonary disease or oxygenation for premature infants requiring complete lung replacement therapy.

Understanding the amorphous-to-microcrystalline silicon transition in SiF{sub 4}/H{sub 2}/Ar gas mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dornstetter, Jean-Christophe; LPICM-CNRS, Ecole Polytechnique, 91128 Palaiseau; Bruneau, Bastien

2014-06-21

We report on the growth of microcrystalline silicon films from the dissociation of SiF{sub 4}/H{sub 2}/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF{sub 4} dissociation, and this removal is promoted by the addition of H{sub 2} which strongly reacts with F to form HF molecules. At low H{sub 2} flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding tomore » the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF{sub 4}/H{sub 2} plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H{sub 2} flow rate.« less

AutoSyP: A Low-Cost, Low-Power Syringe Pump for Use in Low-Resource Settings.

PubMed

Juarez, Alexa; Maynard, Kelley; Skerrett, Erica; Molyneux, Elizabeth; Richards-Kortum, Rebecca; Dube, Queen; Oden, Z Maria

2016-10-05

This article describes the design and evaluation of AutoSyP, a low-cost, low-power syringe pump intended to deliver intravenous (IV) infusions in low-resource hospitals. A constant-force spring within the device provides mechanical energy to depress the syringe plunger. As a result, the device can run on rechargeable battery power for 66 hours, a critical feature for low-resource settings where the power grid may be unreliable. The device is designed to be used with 5- to 60-mL syringes and can deliver fluids at flow rates ranging from 3 to 60 mL/hour. The cost of goods to build one AutoSyP device is approximately $500. AutoSyP was tested in a laboratory setting and in a pilot clinical study. Laboratory accuracy was within 4% of the programmed flow rate. The device was used to deliver fluid to 10 healthy adult volunteers and 30 infants requiring IV fluid therapy at Queen Elizabeth Central Hospital in Blantyre, Malawi. The device delivered fluid with an average mean flow rate error of -2.3% ± 1.9% for flow rates ranging from 3 to 60 mL/hour. AutoSyP has the potential to improve the accuracy and safety of IV fluid delivery in low-resource settings. © The American Society of Tropical Medicine and Hygiene.

Influence of Polymer Type on the Physical Properties and Release Profile of Papaverine Hydrochloride From Hard Gelatin Capsules.

PubMed

Polski, Andrzej; Iwaniak, Karol; Kasperek, Regina; Modrzewska, Joanna; Sobótka-Polska, Karolina; Sławińska, Karolina; Poleszak, Ewa

2015-01-01

The capsule is one of the most important solid dosage forms in the pharmaceutical industry. It is easier and faster to produce than a tablet, because it requires fewer excipients. Generally, capsules are easy to swallow and mask any unpleasant taste of the substances used while their release profiles can be easily modified. Papaverine hydrochloride was used as a model substance to show different release profiles using different excipients. The main aim of the study was to analyze the impact of using different polymers on the release profile of papaverine hydrochloride from hard gelatin capsules. Six series of hard gelatin capsules containing papaverine hydrochloride as a model drug and different excipients were made. Then, the angle of repose, flow rate, mass flow rate and volume flow rate of the powders used for capsule production were analyzed. The uniform weight and disintegration time of the capsules were studied. The dissolution study was performed in a basket apparatus, while the amount of papaverine hydrochloride released was determined spectrophotometrically at 251 nm. Only one formula of powder had satisfactory flow properties, while all formulas had good Hausner ratios. The best properties were from powder containing polyvinylpyrrolidone 10k. The disintegration time of capsules varied from 1:30 min to 2:00 min. As required by Polish Pharmacopoeia X, 80% of the active substance in all cases was released within 15 minutes. The capsules with polyvinylpyrrolidone 10k were characterized by the longest release. On the other hand, capsules containing microcrystalline cellulose had the fastest release profile. Using 10% of different polymers, without changing the other excipients, had a significant impact on the physical properties of the powders and papaverine hydrochloride release profile. The two most preferred capsule formulations contained either polyvinylpyrrolidone 10k or microcrystalline cellulose.

Tomographic reconstruction of heat release rate perturbations induced by helical modes in turbulent swirl flames

NASA Astrophysics Data System (ADS)

Moeck, Jonas P.; Bourgouin, Jean-François; Durox, Daniel; Schuller, Thierry; Candel, Sébastien

2013-04-01

Swirl flows with vortex breakdown are widely used in industrial combustion systems for flame stabilization. This type of flow is known to sustain a hydrodynamic instability with a rotating helical structure, one common manifestation of it being the precessing vortex core. The role of this unsteady flow mode in combustion is not well understood, and its interaction with combustion instabilities and flame stabilization remains unclear. It is therefore important to assess the structure of the perturbation in the flame that is induced by this helical mode. Based on principles of tomographic reconstruction, a method is presented to determine the 3-D distribution of the heat release rate perturbation associated with the helical mode. Since this flow instability is rotating, a phase-resolved sequence of projection images of light emitted from the flame is identical to the Radon transform of the light intensity distribution in the combustor volume and thus can be used for tomographic reconstruction. This is achieved with one stationary camera only, a vast reduction in experimental and hardware requirements compared to a multi-camera setup or camera repositioning, which is typically required for tomographic reconstruction. Different approaches to extract the coherent part of the oscillation from the images are discussed. Two novel tomographic reconstruction algorithms specifically tailored to the structure of the heat release rate perturbations related to the helical mode are derived. The reconstruction techniques are first applied to an artificial field to illustrate the accuracy. High-speed imaging data acquired in a turbulent swirl-stabilized combustor setup with strong helical mode oscillations are then used to reconstruct the 3-D structure of the associated perturbation in the flame.

Development of Heat-Affected Zone Hardness Limits for In-Service Welding

DOT National Transportation Integrated Search

2009-09-29

Welding onto in-service pipelines is frequently required to facilitate a repair or to install a branch connection using the "hot tapping" technique. Welds made in-service cool at an accelerated rate as the result of the ability of the flowing content...

78 FR 4133 - Procurement List; Proposed Additions and Deletion

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-18

... specific tasks including preparation of menu boards, table bussing service, guest flow rate, service of food, replenishing of food, unloading, storing, and shelving of supplies, food preparation, cashier... the event of contingency, perform all required tasks to include cooking to ensure continued service...

A Report on Deliverable Five: Evaluate Current Commercially Available Suction Pump Devices for Use in Prehospital Combat Care

DTIC Science & Technology

Develop a consumer-style report for currently available suction pump devices on the market . List parameters such as suction flow rate, pressure...evaluate whether suction devices that are currently on the market meet these requirements.

MOLECULAR DEMOGRAPHIC HISTORY OF THE ANNUAL SUNFLOWERS HELIANTHUS ANNUUS AND H. PETIOLARIS—LARGE EFFECTIVE POPULATION SIZES AND RATES OF LONG-TERM GENE FLOW

PubMed Central

Strasburg, Jared L.; Rieseberg, Loren H.

2008-01-01

Hybridization between distinct species may lead to introgression of genes across species boundaries, and this pattern can potentially persist for extended periods as long as selection at some loci or genomic regions prevents thorough mixing of gene pools. However, very few reliable estimates of long-term levels of effective migration are available between hybridizing species throughout their history. Accurate estimates of divergence dates and levels of gene flow require data from multiple unlinked loci as well as an analytical framework that can distinguish between lineage sorting and gene flow and incorporate the effects of demographic changes within each species. Here we use sequence data from 18 anonymous nuclear loci in two broadly sympatric sunflower species, Helianthus annuus and H. petiolaris, analyzed within an “isolation with migration” framework to make genome-wide estimates of the ages of these two species, long-term rates of gene flow between them, and effective population sizes and historical patterns of population growth. Our results indicate that H. annuus and H. petiolaris are approximately one million years old and have exchanged genes at a surprisingly high rate (long-term Nef m estimates of approximately 0.5 in each direction), with somewhat higher rates of introgression from H. annuus into H. petiolaris than vice versa. In addition, each species has undergone dramatic population expansion since divergence, and both species have among the highest levels of genetic diversity reported for flowering plants. Our results provide the most comprehensive estimate to date of long-term patterns of gene flow and historical demography in a nonmodel plant system, and they indicate that species integrity can be maintained even in the face of extensive gene flow over a prolonged period. PMID:18462213

Continuous measurements of flow rate in a shallow gravel-bed river by a new acoustic system

NASA Astrophysics Data System (ADS)

Kawanisi, K.; Razaz, M.; Ishikawa, K.; Yano, J.; Soltaniasl, M.

2012-05-01

The continuous measurement of river discharge for long periods of time is crucial in water resource studies. However, the accurate estimation of river discharge is a difficult and labor-intensive procedure; thus, a robust and efficient method of measurement is required. Continuous measurements of flowrate have been carried out in a wide, shallow gravel bed river (water depth ≈ 0.6 m under low-flow conditions, width ≈ 115 m) using Fluvial Acoustic Tomography System (FATS) that has 25 kHz broadband transducers with horizontally omnidirectional and vertically hemispherical beam patterns. Reciprocal sound transmissions were performed between the two acoustic stations located diagonally on both sides of the river. The horizontal distance between the transducers was 301.96 m. FATS enabled the measurement of the depth- and range-averaged sound speed and flow velocity along the ray path. In contrast to traditional point/transect measurements of discharge, in a fraction of a second, FATS covers the entire cross section of river in a single measurement. The flow rates measured by FATS were compared to those estimated by moving boat Acoustic Doppler Current Profiler (ADCP) and rating curve (RC) methods. FATS estimates were in good agreement with ADCP estimates over a range of 20 to 65 m3 s-1. The RMS of residual between the two measurements was 2.41 m3 s-1. On the other hand the flowrate by RC method fairly agreed with FATS estimates for greater discharges than around 40 m3 s-1. This inconsistency arises from biased RC estimates in low flows. Thus, the flow rates derived from FATS could be considered reliable.

Particle Flow Cell Formation at Minimum Fluidization Flow Rates in a Rectangular Gas-Fluidized Bed.

DTIC Science & Technology

1981-03-01

G’ Fluid mass velocity based on voidage area. Ga Galileo number ( Archimedes number). Ge Hypothetical fluid mass velocity required to merely expand a...eighteen inches high above the distributor plate. All joints were glued together and wood screws added in mounting the distributor plate for additional...inch center to center intervals along its length. The air ports are located at the underside of the tube allowing the air to exhaust downward into the

Unsteady Thermocapillary Migration of Isolated Drops in Creeping Flow

NASA Technical Reports Server (NTRS)

Dill, Loren H.; Balasubramaniam, R.

1992-01-01

The problem of an isolated immiscible drop that slowly migrates due to unsteady thermocapillary stresses is considered. All physical properties except for interfacial tension are assumed constant for the two Newtonian fluids. Explicit expressions are found for the migration rate and stream functions in the Laplace domain. The resulting microgravity theory is useful, e.g., in predicting the distance a drop will migrate due to an impulsive interfacial temperature gradient as well as the time required to attain steady flow conditions from an initially resting state.

A Posteriori Quantification of Rate-Controlling Effects from High-Intensity Turbulence-Flame Interactions Using 4D Measurements

DTIC Science & Technology

2016-11-22

Unclassified REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1...compact at all conditions tested, as indicated by the overlap of OH and CH2O distributions. 5. We developed analytical techniques for pseudo- Lagrangian ...condition in a constant density flow requires that the flow divergence is zero, ∇ · ~u = 0. Three smoothing schemes were examined, a moving average (i.e

Particle bed reactor modeling

NASA Technical Reports Server (NTRS)

Sapyta, Joe; Reid, Hank; Walton, Lew

1993-01-01

The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

Thrust Evaluation of an Arcjet Thruster Using Dimethyl Ether as a Propellant

NASA Astrophysics Data System (ADS)

Kakami, Akira; Beppu, Shinji; Maiguma, Muneyuki; Tachibana, Takeshi

This paper describes the performance of an arcjet thruster using dimethyl ether (DME) as a propellant. DME, an ether compound, has adequate characteristics for space propulsion systems; DME is storable in a liquid state without a high pressure or cryogenic device and requires no sophisticated temperature management. DME is gasified and liquefied simply by adjusting temperature, whereas hydrazine, a conventional propellant, requires an iridium-based particulate catalyst for its gasification. In this study, thrust of the designed kW-class DME arcjet thruster is measured with a torsional thrust stand. Thrust measurements show that thrust is increased with propellant mass flow rate, and that thrust using DME propellant is higher than when using nitrogen. The prototype DME arcjet thruster yields a specific impulse of 330 s, a thruster efficiency of 0.14, and a thrust of 0.19 N at 60-mg/s DME mass flow rate at 25-A discharge current. The corresponding discharge power and specific power are 2.3 kW and 39 MJ/kg.

Mediation of tubuloglomerular feedback by adenosine: evidence from mice lacking adenosine 1 receptors.

PubMed

Sun, D; Samuelson, L C; Yang, T; Huang, Y; Paliege, A; Saunders, T; Briggs, J; Schnermann, J

2001-08-14

Adenosine is a determinant of metabolic control of organ function increasing oxygen supply through the A2 class of adenosine receptors and reducing oxygen demand through A1 adenosine receptors (A1AR). In the kidney, activation of A1AR in afferent glomerular arterioles has been suggested to contribute to tubuloglomerular feedback (TGF), the vasoconstriction elicited by elevations in [NaCl] in the macula densa region of the nephron. To further elucidate the role of A1AR in TGF, we have generated mice in which the entire A1AR coding sequence was deleted by homologous recombination. Homozygous A1AR mutants that do not express A1AR mRNA transcripts and do not respond to A1AR agonists are viable and without gross anatomical abnormalities. Plasma and urinary electrolytes were not different between genotypes. Likewise, arterial blood pressure, heart rates, and glomerular filtration rates were indistinguishable between A1AR(+/+), A1AR(+/-), and A1AR(-/-) mice. TGF responses to an increase in loop of Henle flow rate from 0 to 30 nl/min, whether determined as change of stop flow pressure or early proximal flow rate, were completely abolished in A1AR(-/-) mice (stop flow pressure response, -6.8 +/- 0.55 mmHg and -0.4 +/- 0.2 in A1AR(+/+) and A1AR(-/-) mice; early proximal flow rate response, -3.4 +/- 0.4 nl/min and +0.02 +/- 0.3 nl/min in A1AR(+/+) and A1AR(-/-) mice). Absence of TGF responses in A1AR-deficient mice suggests that adenosine is a required constituent of the juxtaglomerular signaling pathway. A1AR null mutant mice are a promising tool to study the functional role of A1AR in different target tissues.

Thermal mapping of a pāhoehoe lava flow, Kīlauea Volcano

NASA Astrophysics Data System (ADS)

Patrick, Matthew; Orr, Tim; Fisher, Gary; Trusdell, Frank; Kauahikaua, James

2017-02-01

Pāhoehoe lava flows are a major component of Hawaiian eruptive activity, and an important part of basaltic volcanism worldwide. In recent years, pāhoehoe lava has destroyed homes and threatened parts of Hawai'i with inundation and disruption. In this study, we use oblique helicopter-borne thermal images to create high spatial resolution ( 1 m) georeferenced thermal maps of the active pāhoehoe flow on Kīlauea Volcano's East Rift Zone. Thermal maps were created on 27 days during 2014-2016 in the course of operational monitoring, encompassing a phase of activity that threatened the town of Pāhoa. Our results illustrate and reinforce how pāhoehoe flows are multicomponent systems consisting of the vent, master tube, distributary tubes, and surface breakouts. The thermal maps accurately depict the distribution and character of pāhoehoe breakouts through time, and also delineate the subsurface lava tube. Surface breakouts were distributed widely across the pāhoehoe flow, with significant portions concurrently active well upslope of the flow front, often concentrated in clusters of activity that evolved through time. Gradual changes to surface breakout distribution and migration relate to intrinsic processes in the flow, including the slow evolution of the distributary tube system. Abrupt disruptions to this system, and the creation of new breakouts (and associated hazards), were triggered by extrinsic forcing-namely fluctuations in lava supply rate at the vent which disrupted the master lava tube. Although the total area of a pāhoehoe flow has been suggested to relate to effusion rate, our results show that changes in the proportion of expansion vs. overplating can complicate this relationship. By modifying existing techniques, we estimate time-averaged discharge rates for the flow during 2014-2016 generally in the range of 1-2 m3 s- 1 (mean: 1.3 ± 0.4 m3 s- 1)-less than half of Kīlauea's typical eruption rate on the East Rift Zone and suggestive of a weak eruptive regime during 2014-2016. We caution, however, that this discharge rate approach requires further independent corroboration. The thermal maps provide the first synoptic characterization of pāhoehoe flow activity at high spatial resolution, essential both for operational hazard assessment and fundamental understanding of pāhoehoe behavior.

Flow Measurement

NASA Technical Reports Server (NTRS)

1988-01-01

Macrodyne, Inc.'s laser velocimeter (LV) is a system used in wind tunnel testing of aircraft, missiles and spacecraft employing electro optical techniques to probe the flow field as the tunnel blows air over a model of flight vehicle and to determine velocity of air and its direction at many points around the model. However, current state-of-the-art minicomputers cannot handle the massive flow of real time data from several sources simultaneously. Langley developed instrument Laser Velocimeter Autocovariance Buffer Interface (LVABI). LVABI is interconnecting instrument between LV and computer. It acquires data from as many as six LV channels at high real time data rates, stores it in memory and sends it to computer on command. LVABI has application in variety of research, industrial and defense functions requiring precise flow measurement.

Progress with multigrid schemes for hypersonic flow problems

NASA Technical Reports Server (NTRS)

Radespiel, R.; Swanson, R. C.

1991-01-01

Several multigrid schemes are considered for the numerical computation of viscous hypersonic flows. For each scheme, the basic solution algorithm uses upwind spatial discretization with explicit multistage time stepping. Two level versions of the various multigrid algorithms are applied to the two dimensional advection equation, and Fourier analysis is used to determine their damping properties. The capabilities of the multigrid methods are assessed by solving three different hypersonic flow problems. Some new multigrid schemes based on semicoarsening strategies are shown to be quite effective in relieving the stiffness caused by the high aspect ratio cells required to resolve high Reynolds number flows. These schemes exhibit good convergence rates for Reynolds numbers up to 200 x 10(exp 6) and Mach numbers up to 25.

Noble gas storage and delivery system for ion propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

2001-01-01

A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

Vulnerability of Xylem Vessels to Cavitation in Sugar Maple. Scaling from Individual Vessels to Whole Branches1

PubMed Central

Melcher, Peter J.; Zwieniecki, Maciej A.; Holbrook, N. Michele

2003-01-01

The relation between xylem vessel age and vulnerability to cavitation of sugar maple (Acer saccharum Marsh.) was quantified by measuring the pressure required to force air across bordered pit membranes separating individual xylem vessels. We found that the bordered pit membranes of vessels located in current year xylem could withstand greater applied gas pressures (3.8 MPa) compared with bordered pit membranes in vessels located in older annular rings (2.0 MPa). A longitudinal transect along 6-year-old branches indicated that the pressure required to push gas across bordered pit membranes of current year xylem did not vary with distance from the growing tip. To understand the contribution of age-related changes in vulnerability to the overall resistance to cavitation, we combined data on the pressure thresholds of individual xylem vessels with measurements of the relative flow rate through each annual ring. The annual ring of the current year contributed only 16% of the total flow measured on 10-cm-long segments cut from 6-year-old branches, but it contributed more than 70% of the total flow when measured through 6-year-old branches to the point of leaf attachment. The vulnerability curve calculated using relative flow rates measured on branch segments were similar to vulnerability curves measured on 6-year-old branches (pressure that reduces hydraulic conductance by 50% = 1.6–2.4 MPa), whereas the vulnerability curve calculated using relative flow rates measured on 6-year-old branches were similar to ones measured on the extension growth of the current year (pressure that reduces hydraulic conductance by 50% = 3.8 MPa). These data suggest that, in sugar maple, the xylem of the current year can withstand larger xylem tensions than older wood and dominates water delivery to leaves. PMID:12692336

Hydrogeologic framework and simulation of shallow ground-water flow in the vicinity of a hazardous-waste landfill near Pinewood, South Carolina

USGS Publications Warehouse

Vroblesky, D.A.

1994-01-01

The geologic units in the vicinity of a hazardous- waste landfill near Pinewood, S.C., were divided into hydrogeologic units on the basis of lithologic and hydrologic characteristics. A quasi-3- dimensional finite-difference ground-water-flow model was constructed to represent the hydrogeologic flamework. The simulation results indicate that if non-reactive constituents were released to the Lang Syne water-bearing zone underlying the central and western pans of the disposal area, the constituents would move in a southwesterly direction at a rate of about one-half to 7 feet per year. Contaminants could move from the Lang Syne water-bearing zone upward to the surficial aquifer, to streams, or to Lake Marion. Although these flow rates indicate that it would require at least 50 years for contaminants to travel between the disposal area and a nearby (400 ft) potential discharge area, the heterogeneity of the site hydrogeology imparts an uncertainty to the conclusion. Faster travel times cannot be ruled out if contamination enters an area having a higher hydraulic conductivity than those determined in this investigation. Faster arrival times at Lake Marion also could result if there are pathways shorter than about 400 feet between contaminated water and an area where it can discharge to the surficial aquifer or to streams. If contaminant releases were to occur on the eastern side of the ground-water mounds, near landfill section II and the southeastern part of land fill section I, initial flow directions would be toward the water-level depression in the eastern part of the facility. Ground water within water- level depression would flow downward, probably to the underlying lower Sawdust Landing water-beating zone. Movement of non-reactive constituents in the tower Sawdust Landing water-bearing zone would be southwestward toward Lake Marion at a rate of about 8 to 20 feet per year. Transport to the lake by this route could require more than 200 years.

Central venous catheter integrity during mechanical power injection of iodinated contrast medium.

PubMed

Macha, Douglas B; Nelson, Rendon C; Howle, Laurens E; Hollingsworth, John W; Schindera, Sebastian T

2009-12-01

To evaluate a widely used nontunneled triple-lumen central venous catheter in order to determine whether the largest of the three lumina (16 gauge) can tolerate high flow rates, such as those required for computed tomographic angiography. Forty-two catheters were tested in vitro, including 10 new and 32 used catheters (median indwelling time, 5 days). Injection pressures were continuously monitored at the site of the 16-gauge central venous catheter hub. Catheters were injected with 300 and 370 mg of iodine per milliliter of iopamidol by using a mechanical injector at increasing flow rates until the catheter failed. The infusion rate, hub pressure, and location were documented for each failure event. The catheter pressures generated during hand injection by five operators were also analyzed. Mean flow rates and pressures at failure were compared by means of two-tailed Student t test, with differences considered significant at P < .05. Injections of iopamidol with 370 mg of iodine per milliliter generate more pressure than injections of iopamidol with 300 mg of iodine per milliliter at the same injection rate. All catheters failed in the tubing external to the patient. The lowest flow rate at which catheter failure occurred was 9 mL/sec. The lowest hub pressure at failure was 262 pounds per square inch gauge (psig) for new and 213 psig for used catheters. Hand injection of iopamidol with 300 mg of iodine per milliliter generated peak hub pressures ranging from 35 to 72 psig, corresponding to flow rates ranging from 2.5 to 5.0 mL/sec. Indwelling use has an effect on catheter material property, but even for used catheters there is a substantial safety margin for power injection with the particular triple-lumen central venous catheter tested in this study, as the manufacturer's recommendation for maximum pressure is 15 psig.

Including local rainfall dynamics and uncertain boundary conditions into a 2-D regional-local flood modelling cascade

NASA Astrophysics Data System (ADS)

Bermúdez, María; Neal, Jeffrey C.; Bates, Paul D.; Coxon, Gemma; Freer, Jim E.; Cea, Luis; Puertas, Jerónimo

2016-04-01

Flood inundation models require appropriate boundary conditions to be specified at the limits of the domain, which commonly consist of upstream flow rate and downstream water level. These data are usually acquired from gauging stations on the river network where measured water levels are converted to discharge via a rating curve. Derived streamflow estimates are therefore subject to uncertainties in this rating curve, including extrapolating beyond the maximum observed ratings magnitude. In addition, the limited number of gauges in reach-scale studies often requires flow to be routed from the nearest upstream gauge to the boundary of the model domain. This introduces additional uncertainty, derived not only from the flow routing method used, but also from the additional lateral rainfall-runoff contributions downstream of the gauging point. Although generally assumed to have a minor impact on discharge in fluvial flood modeling, this local hydrological input may become important in a sparse gauge network or in events with significant local rainfall. In this study, a method to incorporate rating curve uncertainty and the local rainfall-runoff dynamics into the predictions of a reach-scale flood inundation model is proposed. Discharge uncertainty bounds are generated by applying a non-parametric local weighted regression approach to stage-discharge measurements for two gauging stations, while measured rainfall downstream from these locations is cascaded into a hydrological model to quantify additional inflows along the main channel. A regional simplified-physics hydraulic model is then applied to combine these inputs and generate an ensemble of discharge and water elevation time series at the boundaries of a local-scale high complexity hydraulic model. Finally, the effect of these rainfall dynamics and uncertain boundary conditions are evaluated on the local-scale model. Improvements in model performance when incorporating these processes are quantified using observed flood extent data and measured water levels from a 2007 summer flood event on the river Severn. The area of interest is a 7 km reach in which the river passes through the city of Worcester, a low water slope, subcritical reach in which backwater effects are significant. For this domain, the catchment area between flow gauging stations extends over 540 km2. Four hydrological models from the FUSE framework (Framework for Understanding Structural Errors) were set up to simulate the rainfall-runoff process over this area. At this regional scale, a 2-dimensional hydraulic model that solves the local inertial approximation of the shallow water equations was applied to route the flow, whereas the full form of these equations was solved at the local scale to predict the urban flow field. This nested approach hence allows an examination of water fluxes from the catchment to the building scale, while requiring short setup and computational times. An accurate prediction of the magnitude and timing of the flood peak was obtained with the proposed method, in spite of the unusual structure of the rain episode and the complexity of the River Severn system. The findings highlight the importance of estimating boundary condition uncertainty and local rainfall contribution for accurate prediction of river flows and inundation.

Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

NASA Technical Reports Server (NTRS)

Decker, A. J.

1984-01-01

The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

Exploring Inflated Pahohoe Lava Flow Morphologies and the Effects of Cooling Using a New Simulation Approach

NASA Technical Reports Server (NTRS)

Glaze, L. S.; Baloga, S. M.

2014-01-01

Pahoehoe lavas are recognized as an important landform on Earth, Mars and Io. Observations of such flows on Earth (e.g., Figure 1) indicate that the emplacement process is dominated by random effects. Existing models for lobate a`a lava flows that assume viscous fluid flow on an inclined plane are not appropriate for dealing with the numerous random factors present in pahoehoe emplacement. Thus, interpretation of emplacement conditions for pahoehoe lava flows on Mars requires fundamentally different models. A new model that implements a simulation approach has recently been developed that allows exploration of a variety of key influences on pahoehoe lobe emplacement (e.g., source shape, confinement, slope). One important factor that has an impact on the final topographic shape and morphology of a pahoehoe lobe is the volumetric flow rate of lava, where cooling of lava on the lobe surface influences the likelihood of subsequent breakouts.

The effect of visualizing the flow of multimedia content among and inside devices.

PubMed

Lee, Dong-Seok

2009-05-01

This study introduces a user interface, referred to as the flow interface, which provides a graphical representation of the movement of content among and inside audio/video devices. The proposed interface provides a different frame of reference with content-oriented visualization of the generation, manipulation, storage, and display of content as well as input and output. The flow interface was applied to a VCR/DVD recorder combo, one of the most complicated consumer products. A between-group experiment was performed to determine whether the flow interface helps users to perform various tasks and to examine the learning effect of the flow interface, particularly in regard to hooking up and recording tasks. The results showed that participants with access to the flow interface performed better in terms of success rate and elapsed time. In addition, the participants indicated that they could easily understand the flow interface. The potential of the flow interface for application to other audio video devices, and design issues requiring further consideration, are discussed.

Effects of Distortion on Mass Flow Plug Calibration

NASA Technical Reports Server (NTRS)

Sasson, Jonathan; Davis, David O.; Barnhart, Paul J.

2015-01-01

A numerical, and experimental investigation to study the effects of flow distortion on a Mass Flow Plug (MFP) used to control and measure mass-flow during an inlet test has been conducted. The MFP was first calibrated using the WIND-US flow solver for uniform (undistorted) inflow conditions. These results are shown to compare favorably with an experimental calibration under similar conditions. The effects of distortion were investigated by imposing distorted flow conditions taken from an actual inlet test to the inflow plane of the numerical simulation. The computational fluid dynamic (CFD) based distortion study only showed the general trend in mass flow rate. The study used only total pressure as the upstream boundary condition, which was not enough to define the flow. A better simulation requires knowledge of the turbulence structure and a specific distortion pattern over a range of plug positions. It is recommended that future distortion studies utilize a rake with at least the same amount of pitot tubes as the AIP rake.

The impact of bulimia nervosa on oral health: A review of the literature.

PubMed

Rosten, A; Newton, T

2017-11-01

Eating disorders are a potentially life-threatening group of mental disorders, which affect a patient's relationship with food and their body. This manifests itself through chaotic and disordered eating habits. One such eating disorder is bulimia nervosa, which has a lifetime prevalence of 1%. While there is consensus that bulimic behaviour directly causes dental erosion due to vomiting and acidic food choices, there is less clear evidence for a direct link between bulimia nervosa and dental caries, although there does still appear to be an association. Reduced salivary flow rate is a common feature among bulimics, but this is often due to anti-depressant medication rather than dietary habits or vomiting, and the effects are largely limited to unstimulated whole salivary flow rate and don't affect stimulated whole salivary flow rate. Parotid enlargement is present in a number of cases but this tends to be a minority. Further research is required given the limitations of current studies, especially gender imbalances among the populations studied and a lack of clear focus on bulimia nervosa.

Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beyerlein, K. R.; Heymann, M.; Kirian, R.

Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injectionmore » molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquid flow conservation. Finally, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.« less

Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 1: Analysis and results

NASA Technical Reports Server (NTRS)

Anderson, O. L.; Chiappetta, L. M.; Edwards, D. E.; Mcvey, J. B.

1982-01-01

A model for predicting the distribution of liquid fuel droplets and fuel vapor in premixing-prevaporizing fuel-air mixing passages of the direct injection type is reported. This model consists of three computer programs; a calculation of the two dimensional or axisymmetric air flow field neglecting the effects of fuel; a calculation of the three dimensional fuel droplet trajectories and evaporation rates in a known, moving air flow; a calculation of fuel vapor diffusing into a moving three dimensional air flow with source terms dependent on the droplet evaporation rates. The fuel droplets are treated as individual particle classes each satisfying Newton's law, a heat transfer, and a mass transfer equation. This fuel droplet model treats multicomponent fuels and incorporates the physics required for the treatment of elastic droplet collisions, droplet shattering, droplet coalescence and droplet wall interactions. The vapor diffusion calculation treats three dimensional, gas phase, turbulent diffusion processes. The analysis includes a model for the autoignition of the fuel air mixture based upon the rate of formation of an important intermediate chemical species during the preignition period.

Multiphase flowmeter successfully measures three-phase flow at extremely high gas-volume fractions -- Gulf of Suez, Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leggett, R.B.; Borling, D.C.; Powers, B.S.

1998-02-01

A multiphase flowmeter (MPFM) installed in offshore Egypt has accurately measured three-phase flow in extremely gassy flow conditions. The meter is completely nonintrusive, with no moving parts, requires no flow mixing before measurement, and has no bypass loop to remove gas before multiphase measurement. Flow regimes observed during the field test of this meter ranged from severe slugging to annular flow caused by the dynamics of gas-lift gas in the production stream. Average gas-volume fraction ranged from 93 to 98% during tests conducted on seven wells. The meter was installed in the Gulf of Suez on a well protector platformmore » in the Gulf of Suez Petroleum Co. (Gupco) October field, and was placed in series with a test separator located on a nearby production platform. Wells were individually tested with flow conditions ranging from 1,300 to 4,700 B/D fluid, 2.4 to 3.9 MMscf/D of gas, and water cuts from 1 to 52%. The meter is capable of measuring water cuts up to 100%. Production was routed through both the MPFM and the test separator simultaneously as wells flowed with the assistance of gas-lift gas. The MPFM measured gas and liquid rates to within {+-} 10% of test-separator reference measurement flow rates, and accomplished this at gas-volume fractions from 93 to 96%. At higher gas-volume fractions up to 98%, accuracy deteriorated but the meter continued to provide repeatable results.« less

A survey of aerobraking orbital transfer vehicle design concepts

NASA Technical Reports Server (NTRS)

Park, Chul

1987-01-01

The five existing design concepts of the aerobraking orbital transfer vehicle (namely, the raked sphere-cone designs, conical lifting-brake, raked elliptic-cone, lifting-body, and ballute) are reviewed and critiqued. Historical backgrounds, and the geometrical, aerothermal, and operational features of these designs are reviewed first. Then, the technological requirements for the vehicle (namely, navigation, aerodynamic stability and control, afterbody flow impingement, nonequilibrium radiation, convective heat-transfer rates, mission abort and multiple atmospheric passes, transportation and construction, and the payload-to-vehicle weight requirements) are delineated by summarizing the recent advancements made on these issues. Each of the five designs are critiqued and rated on these issues. The highest and the lowest ratings are given to the raked sphere-cone and the ballute design, respectively.

Patient-specific in vitro models for hemodynamic analysis of congenital heart disease - Additive manufacturing approach.

PubMed

Medero, Rafael; García-Rodríguez, Sylvana; François, Christopher J; Roldán-Alzate, Alejandro

2017-03-21

Non-invasive hemodynamic assessment of total cavopulmonary connection (TCPC) is challenging due to the complex anatomy. Additive manufacturing (AM) is a suitable alternative for creating patient-specific in vitro models for flow measurements using four-dimensional (4D) Flow MRI. These in vitro systems have the potential to serve as validation for computational fluid dynamics (CFD), simulating different physiological conditions. This study investigated three different AM technologies, stereolithography (SLA), selective laser sintering (SLS) and fused deposition modeling (FDM), to determine differences in hemodynamics when measuring flow using 4D Flow MRI. The models were created using patient-specific MRI data from an extracardiac TCPC. These models were connected to a perfusion pump circulating water at three different flow rates. Data was processed for visualization and quantification of velocity, flow distribution, vorticity and kinetic energy. These results were compared between each model. In addition, the flow distribution obtained in vitro was compared to in vivo. The results showed significant difference in velocities measured at the outlets of the models that required internal support material when printing. Furthermore, an ultrasound flow sensor was used to validate flow measurements at the inlets and outlets of the in vitro models. These results were highly correlated to those measured with 4D Flow MRI. This study showed that commercially available AM technologies can be used to create patient-specific vascular models for in vitro hemodynamic studies at reasonable costs. However, technologies that do not require internal supports during manufacturing allow smoother internal surfaces, which makes them better suited for flow analyses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Getting the gas out - developing gas networks in magmatic systems

NASA Astrophysics Data System (ADS)

Cashman, Katharine; Rust, Alison; Oppenheimer, Julie; Belien, Isolde

2015-04-01

Volcanic eruption style, and explosive potential, are strongly controlled by the pre-eruptive history of the magmatic volatiles: specifically, the more efficient the gas loss prior to eruption, the lower the likelihood of primary (magmatic) explosive activity. Commonly considered gas loss mechanisms include separated flow, where individual bubbles (or bubble clouds) travel at a rate that is faster than the host magma, and permeable flow, where gas escapes through permeable (connected) pathways developed within a (relatively) static matrix. Importantly, gas loss via separated flow is episodic, while gas loss via permeable flow is likely to be continuous. Analogue experiments and numerical models on three phase (solid-liquid-gas) systems also suggest a third mechanism of gas loss that involves the opening and closing of 'pseudo fractures'. Pseudo fractures form at a critical crystallinity that is close to the maximum particle packing. Fractures form by local rearrangement of solid particles and liquid to form a through-going gas fracture; gas escape is episodic, and modulated by the available gas volume and the rate of return flow of interstitial liquid back into the fracture. In all of the gas escape scenarios described above, a fundamental control on gas behaviour is the melt viscosity, which affects the rate of individual bubble rise, the rate of bubble expansion, the rate of film thinning (required for bubble coalescence), and the rate of melt flow into gas-generated fractures. From the perspective of magma degassing, rates of gas expansion and film thinning are key to the formation of an interconnected (permeable) gas pathway. Experiments with both analogue and natural materials show that bubble coalescence is relatively slow, and, in particle-poor melts, does not necessarily create permeable gas networks. As a result, degassing efficiency is modulated by the time scales required either (1) to produce large individual bubbles or bubble clouds (in low viscosity melts) or (2) to develop sufficient porosity for full connectivity of a bubble network (in high viscosity melts). In contrast, our experiments suggest that the presence of solid particles may greatly enhance gas escape. On the one hand, the addition of solid particles increases the bulk viscosity of the mixture, which reduces the migration rate of large single bubbles. On the other hand, the strength of networks created by touching crystals inhibits bulk magma deformation and forces smaller bubbles to deform to occupy the spaces between particles, thereby increasing both the bubble shape anisotropy and, correspondingly, the probability of bubble coalescence. Gas pathways created in this way take advantage of inhomogeneities in the spatial distribution of crystals and allow large-scale gas release at relatively low vesicularities. This mechanism of gas escape is likely to be important not only in mafic arc volcanoes, where shallow conduits are likely to be highly crystalline, but also for degassing of crystal-mush-dominated magmatic systems.

Refuge alternatives relief valve testing and design with updated test stand.

PubMed

Lutz, T J; Bissert, P T; Homce, G T; Yonkey, J A

2018-03-01

Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-the-shelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m 3 /min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.

Lead Coolant Test Facility Systems Design, Thermal Hydraulic Analysis and Cost Estimate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soli Khericha; Edwin Harvego; John Svoboda

2012-01-01

The Idaho National Laboratory prepared a preliminary technical and functional requirements (T&FR), thermal hydraulic design and cost estimate for a lead coolant test facility. The purpose of this small scale facility is to simulate lead coolant fast reactor (LFR) coolant flow in an open lattice geometry core using seven electrical rods and liquid lead or lead-bismuth eutectic coolant. Based on review of current world lead or lead-bismuth test facilities and research needs listed in the Generation IV Roadmap, five broad areas of requirements were identified as listed: (1) Develop and Demonstrate Feasibility of Submerged Heat Exchanger; (2) Develop and Demonstratemore » Open-lattice Flow in Electrically Heated Core; (3) Develop and Demonstrate Chemistry Control; (4) Demonstrate Safe Operation; and (5) Provision for Future Testing. This paper discusses the preliminary design of systems, thermal hydraulic analysis, and simplified cost estimate. The facility thermal hydraulic design is based on the maximum simulated core power using seven electrical heater rods of 420 kW; average linear heat generation rate of 300 W/cm. The core inlet temperature for liquid lead or Pb/Bi eutectic is 4200 C. The design includes approximately seventy-five data measurements such as pressure, temperature, and flow rates. The preliminary estimated cost of construction of the facility is $3.7M (in 2006 $). It is also estimated that the facility will require two years to be constructed and ready for operation.« less

Melt Flow before Crystal Seeding in Cz Si Growth with Transversal MF

NASA Astrophysics Data System (ADS)

Iizuka, Masaya; Mukaiyama, Yuji; Demina, S. E.; Kalaev, V. V.

2017-06-01

Industrial Cz growth of Si crystal of 300 mm and higher diameter usually requires DC magnetic fields (MFs) to suppress turbulence in the melt. We present 3D unsteady analysis of melt turbulent convection in an industrial Cz system coupled with the effect of the transversal MF for different argon gas flow rates for the stage before crystal seeding. We have performed detailed 2D axisymmetric modeling of global heat transfer in the whole Cz furnace. Radiative heat fluxes obtained in 2D modeling have been used in detailed 3D steady and unsteady modeling of crystallization zone. LES method is applied as a predictive approach for modeling of turbulent flow of silicon melt. We have obtained flow structure and temperature distribution in the melt, which were different from previously reported data. We have observed a well-fixed dark spike which includes low temperature melt area on the melt free surface in MF cases. These results indicates that MF and argon flow rate conditions are important to achieve stable positioning of the dark spike on the melt free surface for optimized crystal seeding without uncontrollable meltdown and single crystal structure loss.

Safety, efficiency and learning curves in robotic surgery: a human factors analysis.

PubMed

Catchpole, Ken; Perkins, Colby; Bresee, Catherine; Solnik, M Jonathon; Sherman, Benjamin; Fritch, John; Gross, Bruno; Jagannathan, Samantha; Hakami-Majd, Niv; Avenido, Raymund; Anger, Jennifer T

2016-09-01

Expense, efficiency of use, learning curves, workflow integration and an increased prevalence of serious incidents can all be barriers to adoption. We explored an observational approach and initial diagnostics to enhance total system performance in robotic surgery. Eighty-nine robotic surgical cases were observed in multiple operating rooms using two different surgical robots (the S and Si), across several specialties (Urology, Gynecology, and Cardiac Surgery). The main measures were operative duration and rate of flow disruptions-described as 'deviations from the natural progression of an operation thereby potentially compromising safety or efficiency.' Contextual parameters collected were surgeon experience level and training, type of surgery, the model of robot and patient factors. Observations were conducted across four operative phases (operating room pre-incision; robot docking; main surgical intervention; post-console). A mean of 9.62 flow disruptions per hour (95 % CI 8.78-10.46) were predominantly caused by coordination, communication, equipment and training problems. Operative duration and flow disruption rate varied with surgeon experience (p = 0.039; p < 0.001, respectively), training cases (p = 0.012; p = 0.007) and surgical type (both p < 0.001). Flow disruption rates in some phases were also sensitive to the robot model and patient characteristics. Flow disruption rate is sensitive to system context and generates improvement diagnostics. Complex surgical robotic equipment increases opportunities for technological failures, increases communication requirements for the whole team, and can reduce the ability to maintain vision in the operative field. These data suggest specific opportunities to reduce the training costs and the learning curve.

Developing New Modelling Tools for Environmental Flow Assessment in Regulated Salmon Rivers

NASA Astrophysics Data System (ADS)

Geris, Josie; Soulsby, Chris; Tetzlaff, Doerthe

2013-04-01

There is a strong political drive in Scotland to meet all electricity demands from renewable sources by 2020. In Scotland, hydropower generation has a long history and is a key component of this strategy. However, many rivers sustain freshwater communities that have both high conservation status and support economically important Atlantic salmon fisheries. Both new and existing hydropower schemes must be managed in accordance with the European Union's Water Framework Directive (WFD), which requires that all surface water bodies achieve good ecological status or maintain good ecological potential. Unfortunately, long-term river flow monitoring is sparse in the Scottish Highlands and there are limited data for defining environmental flows. The River Tay is the most heavily regulated catchment in the UK. To support hydropower generation, it has an extensive network of inter- and intra- catchment transfers, in addition to a large number of regulating reservoirs for which abstraction legislation often only requires minimum compensation flows. The Tay is also considered as one of Scotland's most important rivers for Atlantic salmon (Salmo salar), and there is considerable uncertainty as to how best change reservoir operations to improve the ecological potential of the river system. It is now usually considered that environmental flows require more than a minimum compensation flow, and instead should cover a range of hydrological flow aspects that represent ecologically relevant streamflow attributes, including magnitude, timing, duration, frequency and rate of change. For salmon, these hydrological indices are of particular interest, with requirements varying at different stages of their life cycle. To meet the WFD requirements, rationally alter current abstraction licences and provide an evidence base for regulating new hydropower schemes, advanced definitions for abstraction limits and ecologically appropriate flow releases are desirable. However, a good understanding of the natural flow variability and the hydrological impacts of the regulation is unavailable, partly because pre-regulation data of existing hydropower schemes are lacking. Here we develop a novel modelling approach for characterising natural flow regimes and defining hydrological flow indices. This allows us to quantitatively assess the impacts of hydropower to better inform environmental flow requirements for the Atlantic salmon river ecosystem. Results are presented for the River Lyon (390 km2), a regulated headwater catchment of the River Tay. The HBV hydrological rainfall-runoff model is used to simulate flows, based on calibrated parameters from regulated flow data, with the current hydropower scheme active. For this, the HBV model is adapted to be able to incorporate water transfers and regulated flows. The natural hydrological indices are derived from the simulated pre-regulation data, and compared with those of the regulated data to investigate the impact of the regulation on these at different critical times for Atlantic salmon. The sensitivity of the system to change is also investigated to explore the extent to which flow variables can be modified without major degradation to the river's ecosystem, while still maintaining viable hydropower generation. The modelling approach presented will provide the basis for assessing impacts on hydrological flow indices and informing environmental flows in regions with similar heavily regulated mountain river ecosystems.

Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

NASA Technical Reports Server (NTRS)

Micklow, Gerald J.

1996-01-01

The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

Yield Stress Reduction of DWPF Melter Feed Slurries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stone, M.E.; Smith, M.E.

2007-07-01

The Defense Waste Processing Facility (DWPF) at the Savannah River Site vitrifies High Level Waste for repository internment. The process consists of three major steps: waste pretreatment, vitrification, and canister decontamination/sealing. The HLW consists of insoluble metal hydroxides and soluble sodium salts. The pretreatment process acidifies the sludge with nitric and formic acids, adds the glass formers as glass frit, then concentrates the resulting slurry to approximately 50 weight percent (wt%) total solids. This slurry is fed to the joule-heated melter where the remaining water is evaporated followed by calcination of the solids and conversion to glass. The Savannah Rivermore » National Laboratory (SRNL) is currently assisting DWPF efforts to increase throughput of the melter. As part of this effort, SRNL has investigated methods to increase the solids content of the melter feed to reduce the heat load required to complete the evaporation of water and allow more of the energy available to calcine and vitrify the waste. The process equipment in the facility is fixed and cannot process materials with high yield stresses, therefore increasing the solids content will require that the yield stress of the melter feed slurries be reduced. Changing the glass former added during pretreatment from an irregularly shaped glass frit to nearly spherical beads was evaluated. The evaluation required a systems approach which included evaluations of the effectiveness of beads in reducing the melter feed yield stress as well as evaluations of the processing impacts of changing the frit morphology. Processing impacts of beads include changing the settling rate of the glass former (which effects mixing and sampling of the melter feed slurry and the frit addition equipment) as well as impacts on the melt behavior due to decreased surface area of the beads versus frit. Beads were produced from the DWPF process frit by fire polishing. The frit was allowed to free fall through a flame, then quenched with a water spray. Approximately 90% of the frit was converted to beads by this process. Yield stress reduction was measured by preparing melter feed slurries (using nonradioactive HLW simulants) that contain beads and comparing the yield stress with melter feed containing frit. A second set of tests was performed with beads of various diameters to determine if a decrease in diameter affected the results. Smaller particle size was shown to increase yield stress when frit is utilized. The settling rate of the beads was required to match the settling rate of the frit, therefore a decrease in particle size was anticipated. Settling tests were conducted in water, xanthan gum solutions, and in non-radioactive simulants of the HLW. The tests used time-lapse video-graphy as well as solids sampling to evaluate the settling characteristics of beads compared to frit of the same particle size. A preliminary melt rate evaluation was performed using a dry-fed Melt Rate Furnace (MRF) developed by SRNL. Preliminary evaluation of the impact of beading the frit on the frit addition system were completed by conducting flow loop testing. A recirculation loop was built with a total length of about 30 feet. Pump power, flow rate, outlet pressure, and observations of the flow in the horizontal upper section of the loop were noted. The recirculation flow was then gradually reduced and the above items recorded until settling was noted in the recirculation line. Overall, the data shows that the line pressure increased as the solids were increased for the same flow rate. In addition, the line pressure was higher for Frit 320 than the beads at the same solids level and flow. With the observations, a determination of minimum velocity to prevent settling could be done, but a graph of the line pressures versus velocity for the various tests was deemed to more objective. The graph shows that the inflection point in pressure drop is about the same for the beads and Frit 320. This indicates that the bead slurry would not require higher flows rates than frit slurry at DWPF during transfers. Another key finding was that the pump impeller was not significantly damaged by the bead slurry, while the Frit 320 slurry rapidly destroyed the impeller. Evidence of this was first observed when black particles were seen in the Frit 320 slurry being recirculated and then confirmed by a post-test inspection of the impeller. Finally, the pumping of bead slurry could be recovered even if flow is stopped. The Frit 320 slurry could not be restarted after stopping flow due to the nature of the frit to pack tightly when settled. Beads were shown to represent a significant process improvement versus frit for the DWPF process in lowering yield stress of the melter feed. Lower erosion of process equipment is another expected benefit.« less

Applicator Training Manual for: Aquatic Weed Control.

ERIC Educational Resources Information Center

Herron, James W.

The aquatic weeds discussed in this manual include algae, floating weeds, emersed weeds, and submerged weeds. Specific requirements for pesticide application are given for static water, limited flow, and moving water situations. Secondary effects of improper application rates and faulty application are described. Finally, techniques of limited…

40 CFR 1065.307 - Linearity verification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... different flow rates. Use a gravimetric reference measurement (such as a scale, balance, or mass comparator... the gas-division system to divide the span gas with purified air or nitrogen. Select gas divisions... verification for gravimetric PM balances, use external calibration weights that that meet the requirements in...

40 CFR 89.331 - Test conditions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Test conditions. 89.331 Section 89.331... EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Emission Test Equipment Provisions § 89.331 Test conditions. (a) General requirements. Calculate all volumes and volumetric flow rates at...

Leading-edge flow criticality as a governing factor in leading-edge vortex initiation in unsteady airfoil flows

NASA Astrophysics Data System (ADS)

Ramesh, Kiran; Granlund, Kenneth; Ol, Michael V.; Gopalarathnam, Ashok; Edwards, Jack R.

2018-04-01

A leading-edge suction parameter (LESP) that is derived from potential flow theory as a measure of suction at the airfoil leading edge is used to study initiation of leading-edge vortex (LEV) formation in this article. The LESP hypothesis is presented, which states that LEV formation in unsteady flows for specified airfoil shape and Reynolds number occurs at a critical constant value of LESP, regardless of motion kinematics. This hypothesis is tested and validated against a large set of data from CFD and experimental studies of flows with LEV formation. The hypothesis is seen to hold except in cases with slow-rate kinematics which evince significant trailing-edge separation (which refers here to separation leading to reversed flow on the aft portion of the upper surface), thereby establishing the envelope of validity. The implication is that the critical LESP value for an airfoil-Reynolds number combination may be calibrated using CFD or experiment for just one motion and then employed to predict LEV initiation for any other (fast-rate) motion. It is also shown that the LESP concept may be used in an inverse mode to generate motion kinematics that would either prevent LEV formation or trigger the same as per aerodynamic requirements.

Investigation of Spray Cooling Schemes for Dynamic Thermal Management

NASA Astrophysics Data System (ADS)

Yata, Vishnu Vardhan Reddy

This study aims to investigate variable flow and intermittent flow spray cooling characteristics for efficiency improvement in active two-phase thermal management systems. Variable flow spray cooling scheme requires control of pump input voltage (or speed), while intermittent flow spray cooling scheme requires control of solenoid valve duty cycle and frequency. Several testing scenarios representing dynamic heat load conditions are implemented to characterize the overall performance of variable flow and intermittent flow spray cooling cases in comparison with the reference, steady flow spray cooling case with constant flowrate, continuous spray cooling. Tests are conducted on a small-scale, closed loop spray cooling system featuring a pressure atomized spray nozzle. HFE-7100 dielectric liquid is selected as the working fluid. Two types of test samples are prepared on 10 mm x 10 mm x 2 mm copper substrates with matching size thick film resistors attached onto the opposite side, to generate heat and simulate high heat flux electronic devices. The test samples include: (i) plain, smooth surface, and (ii) microporous surface featuring 100 ?m thick copper-based coating prepared by dual stage electroplating technique. Experimental conditions involve HFE-7100 at atmospheric pressure and 30°C and 10°C subcooling. Steady flow spray cooling tests are conducted at flow rates of 2-5 ml/cm2.s, by controlling the heat flux in increasing steps, and recording the corresponding steady-state temperatures to obtain cooling curves in the form of surface superheat vs. heat flux. Variable flow and intermittent flow spray cooling tests are done at selected flowrate and subcooling conditions to investigate the effects of dynamic flow conditions on maintaining the target surface temperatures defined based on reference steady flow spray cooling performance.

In vivo study of flow-rate accuracy of the MedStream Programmable Infusion System.

PubMed

Venugopalan, Ramakrishna; Ginggen, Alec; Bork, Toralf; Anderson, William; Buffen, Elaine

2011-01-01

  Flow-rate accuracy and precision are important parameters to optimizing the efficacy of programmable intrathecal (IT) infusion pump delivery systems. Current programmable IT pumps are accurate within ±14.5% of their programmed infusion rate when assessed under ideal environmental conditions and specific flow-rate settings in vitro. We assessed the flow-rate accuracy of a novel programmable pump system across its entire flow-rate range under typical conditions in sheep (in vivo) and nominal conditions in vitro.   The flow-rate accuracy of the MedStream Programmable Pump was assessed in both the in vivo and in vitro settings. In vivo flow-rate accuracy was assessed in 16 sheep at various flow-rates (producing 90 flow intervals) more than 90 ± 3 days. Pumps were then explanted, re-sterilized and in vitro flow-rate accuracy was assessed at 37°C and 1013 mBar (80 flow intervals).   In vivo (sheep body temperatures 38.1°C-39.8°C), mean ± SD flow-rate error was 9.32% ± 9.27% and mean ± SD leak-rate was 0.028 ± 0.08 mL/day. Following explantation, mean in vitro flow-rate error and leak-rate were -1.05% ± 2.55% and 0.003 ± 0.004 mL/day (37°C, 1013 mBar), respectively.   The MedStream Programmable Pump demonstrated high flow-rate accuracy when tested in vivo and in vitro at normal body temperature and environmental pressure as well as when tested in vivo at variable sheep body temperature. The flow-rate accuracy of the MedStream Programmable Pump across its flow-rate range, compares favorably to the accuracy of current clinically utilized programmable IT infusion pumps reported at specific flow-rate settings and conditions. © 2011 International Neuromodulation Society.

Filament turnover tunes both force generation and dissipation to control long-range flows in a model actomyosin cortex

PubMed Central

McCall, Patrick M.; Gardel, Margaret L.; Munro, Edwin M.

2017-01-01

Actomyosin-based cortical flow is a fundamental engine for cellular morphogenesis. Cortical flows are generated by cross-linked networks of actin filaments and myosin motors, in which active stress produced by motor activity is opposed by passive resistance to network deformation. Continuous flow requires local remodeling through crosslink unbinding and and/or filament disassembly. But how local remodeling tunes stress production and dissipation, and how this in turn shapes long range flow, remains poorly understood. Here, we study a computational model for a cross-linked network with active motors based on minimal requirements for production and dissipation of contractile stress: Asymmetric filament compliance, spatial heterogeneity of motor activity, reversible cross-links and filament turnover. We characterize how the production and dissipation of network stress depend, individually, on cross-link dynamics and filament turnover, and how these dependencies combine to determine overall rates of cortical flow. Our analysis predicts that filament turnover is required to maintain active stress against external resistance and steady state flow in response to external stress. Steady state stress increases with filament lifetime up to a characteristic time τm, then decreases with lifetime above τm. Effective viscosity increases with filament lifetime up to a characteristic time τc, and then becomes independent of filament lifetime and sharply dependent on crosslink dynamics. These individual dependencies of active stress and effective viscosity define multiple regimes of steady state flow. In particular our model predicts that when filament lifetimes are shorter than both τc and τm, the dependencies of effective viscosity and steady state stress on filament turnover cancel one another, such that flow speed is insensitive to filament turnover, and shows a simple dependence on motor activity and crosslink dynamics. These results provide a framework for understanding how animal cells tune cortical flow through local control of network remodeling. PMID:29253848

Progress Toward an Efficient and General CFD Tool for Propulsion Design/Analysis

NASA Technical Reports Server (NTRS)

Cox, C. F.; Cinnella, P.; Westmoreland, S.

1996-01-01

The simulation of propulsive flows inherently involves chemical activity. Recent years have seen substantial strides made in the development of numerical schemes for reacting flowfields, in particular those involving finite-rate chemistry. However, finite-rate calculations are computationally intensive and require knowledge of the actual kinetics, which are not always known with sufficient accuracy. Alternatively, flow simulations based on the assumption of local chemical equilibrium are capable of obtaining physically reasonable results at far less computational cost. The present study summarizes the development of efficient numerical techniques for the simulation of flows in local chemical equilibrium, whereby a 'Black Box' chemical equilibrium solver is coupled to the usual gasdynamic equations. The generalization of the methods enables the modelling of any arbitrary mixture of thermally perfect gases, including air, combustion mixtures and plasmas. As demonstration of the potential of the methodologies, several solutions, involving reacting and perfect gas flows, will be presented. Included is a preliminary simulation of the SSME startup transient. Future enhancements to the proposed techniques will be discussed, including more efficient finite-rate and hybrid (partial equilibrium) schemes. The algorithms that have been developed and are being optimized provide for an efficient and general tool for the design and analysis of propulsion systems.

Research on Streamlines and Aerodynamic Heating for Unstructured Grids on High-Speed Vehicles

NASA Technical Reports Server (NTRS)

DeJarnette, Fred R.; Hamilton, H. Harris (Technical Monitor)

2001-01-01

Engineering codes are needed which can calculate convective heating rates accurately and expeditiously on the surfaces of high-speed vehicles. One code which has proven to meet these needs is the Langley Approximate Three-Dimensional Convective Heating (LATCH) code. It uses the axisymmetric analogue in an integral boundary-layer method to calculate laminar and turbulent heating rates along inviscid surface streamlines. It requires the solution of the inviscid flow field to provide the surface properties needed to calculate the streamlines and streamline metrics. The LATCH code has been used with inviscid codes which calculated the flow field on structured grids, Several more recent inviscid codes calculate flow field properties on unstructured grids. The present research develops a method to calculate inviscid surface streamlines, the streamline metrics, and heating rates using the properties calculated from inviscid flow fields on unstructured grids. Mr. Chris Riley, prior to his departure from NASA LaRC, developed a preliminary code in the C language, called "UNLATCH", to accomplish these goals. No publication was made on his research. The present research extends and improves on the code developed by Riley. Particular attention is devoted to the stagnation region, and the method is intended for programming in the FORTRAN 90 language.