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Sample records for air pressure differential

  1. Differential air sac pressures in diving tufted ducks Aythya fuligula.

    PubMed

    Boggs, D F; Butler, P J; Wallace, S E

    1998-09-01

    The air in the respiratory system of diving birds contains a large proportion of the body oxygen stores, but it must be in the lungs for gas exchange with blood to occur. To test the hypothesis that locomotion induces mixing of air sac air with lung air during dives, we measured differential pressures between the interclavicular and posterior thoracic air sacs in five diving tufted ducks Aythya fuligula. The peak differential pressure between posterior thoracic and interclavicular air sacs, 0.49+/-0.13 kPa (mean +/- s.d.), varied substantially during underwater paddling as indicated by gastrocnemius muscle activity. These data support the hypothesis that locomotion, perhaps through associated abdominal muscle activity, intermittently compresses the posterior air sacs more than the anterior ones. The result is differential pressure fluctuations that might induce the movement of air between air sacs and through the lungs during dives. PMID:9716518

  2. Design of a MEMS piezoresistive differential pressure sensor with small thermal hysteresis for air data modules

    NASA Astrophysics Data System (ADS)

    Song, Jin Woo; Lee, Jang-Sub; An, Jun-Eon; Park, Chan Gook

    2015-06-01

    The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process.

  3. Design of a MEMS piezoresistive differential pressure sensor with small thermal hysteresis for air data modules.

    PubMed

    Song, Jin Woo; Lee, Jang-Sub; An, Jun-Eon; Park, Chan Gook

    2015-06-01

    The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process.

  4. Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

    2007-01-01

    Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  5. Cellular Attachment and Differentiation on Titania Nanotubes Exposed to Air- or Nitrogen-Based Non-Thermal Atmospheric Pressure Plasma

    PubMed Central

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity

  6. Cellular attachment and differentiation on titania nanotubes exposed to air- or nitrogen-based non-thermal atmospheric pressure plasma.

    PubMed

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity

  7. Air pressure measurement

    NASA Technical Reports Server (NTRS)

    Ballard, H. N.

    1978-01-01

    The pressure measurement was made by a Model 830J Rosemont sensor which utilized the principle of a changing pressure to change correspondingly the capacitance of the pressure sensitive element. The sensor's range was stated to be from zero to 100 Torr (14 km); however, the sensor was not activated until an altitude of 20 km (41 Torr) was reached during the balloon ascent. The resolution of the sensor was specified by the manufacturer as infinitesimal; however, associated electronic and pressure readout systems limit the resolution to .044 Torr. Thus in the vicinity of an altitude of 30 km the pressure resolution corresponded to an altitude resolution of approximately 33 meters.

  8. Air separation with temperature and pressure swing

    DOEpatents

    Cassano, Anthony A.

    1986-01-01

    A chemical absorbent air separation process is set forth which uses a temperature swing absorption-desorption cycle in combination with a pressure swing wherein the pressure is elevated in the desorption stage of the process.

  9. Differential pressure pin discharge apparatus

    DOEpatents

    Oakley, D.J.

    1984-05-30

    Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pins passageway extending through the assembly.

  10. Differential pressure pin discharge apparatus

    DOEpatents

    Oakley, David J.

    1987-02-03

    Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pin passageway extending through the assembly.

  11. Differential pressure pin discharge apparatus

    DOEpatents

    Oakley, David J.

    1987-01-01

    Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pin passageway extending through the assembly.

  12. High-pressure differential scanning microcalorimeter.

    PubMed

    Senin, A A; Dzhavadov, L N; Potekhin, S A

    2016-03-01

    A differential scanning microcalorimeter for studying thermotropic conformational transitions of biopolymers at high pressure has been designed. The calorimeter allows taking measurements of partial heat capacity of biopolymer solutions vs. temperature at pressures up to 3000 atm. The principles of operation of the device, methods of its calibration, as well as possible applications are discussed. PMID:27036806

  13. Monitoring Air Circulation Under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim

    Adequate air circulation is required for controlled environments to maintain uniform temperature and humidity control, and hence the ability to measure air flow accurately is important. Human and associated life support habitats (e.g.,. plant production systems) for future space missions will likely be operated at pressures less than 100 kPa to minimize gas leakage and structural mass. Under such reduced pressures, the outputs from conventional anemometers for monitoring air flow can change and require re-calibration. These effects of atmospheric pressure on different types of air flow measurements are not completely understood; hence we compared the performance of several air flow sensors across a range of hypobaric pressures. Sensors included a propeller type anemometer, a hot-wire anemometer, and a Pitot-tube based device. Theoretical schematics (including mathematical models) underlying these measurements were developed. Results demonstrated that changes in sensor outputs were predictable based on their operating principles, and that corrections could be developed for sensors calibrated under normal Earth atmosphere pressure ( 100 kPa) and then used at different pressures. The potential effects of hypobaric atmospheres and their altered air flows on plant physiology are also discussed.

  14. Modern differential pressure gas counter (WIGZ) measurement

    NASA Astrophysics Data System (ADS)

    Brandt, O.

    1985-07-01

    The differential pressure gas counter facility developed to measure gas flow rate on orifice plates in the pipe system transporting Soviet gas to West Germany and France was equipped with small computers which record all the parameters of a measuring system and calculate the standard volume and the quantity of heat. These parameters are used to calibrate the facility. The differential pressure indicators and operating densitometers, the standard densitometers, pressure and temperature sensors, and calorific value indicators are described. The operation of and processing by the 16-bit microprocessor computers of all parameters are summarized. The central computer and the performance recording facility are presented.

  15. Microfluidic pressure sensing using trapped air compression.

    PubMed

    Srivastava, Nimisha; Burns, Mark A

    2007-05-01

    We have developed a microfluidic method for measuring the fluid pressure head experienced at any location inside a microchannel. The principal component is a microfabricated sealed chamber with a single inlet and no exit; the entrance to the single inlet is positioned at the location where pressure is to be measured. The pressure measurement is then based on monitoring the movement of a liquid-air interface as it compresses air trapped inside the microfabricated sealed chamber and calculating the pressure using the ideal gas law. The method has been used to measure the pressure of the air stream and continuous liquid flow inside microfluidic channels (d approximately 50 microm). Further, a pressure drop has also been measured using multiple microfabricated sealed chambers. For air pressure, a resolution of 700 Pa within a full-scale range of 700-100 kPa was obtained. For liquids, pressure drops as low as 70 Pa were obtained in an operating range from 70 Pa to 10 kPa. Since the method primarily uses a microfluidic sealed chamber, it does not require additional fabrication steps and may easily be incorporated in several lab-on-a-chip fluidic applications for laminar as well as turbulent flow conditions. PMID:17476384

  16. Microfluidic pressure sensing using trapped air compression.

    PubMed

    Srivastava, Nimisha; Burns, Mark A

    2007-05-01

    We have developed a microfluidic method for measuring the fluid pressure head experienced at any location inside a microchannel. The principal component is a microfabricated sealed chamber with a single inlet and no exit; the entrance to the single inlet is positioned at the location where pressure is to be measured. The pressure measurement is then based on monitoring the movement of a liquid-air interface as it compresses air trapped inside the microfabricated sealed chamber and calculating the pressure using the ideal gas law. The method has been used to measure the pressure of the air stream and continuous liquid flow inside microfluidic channels (d approximately 50 microm). Further, a pressure drop has also been measured using multiple microfabricated sealed chambers. For air pressure, a resolution of 700 Pa within a full-scale range of 700-100 kPa was obtained. For liquids, pressure drops as low as 70 Pa were obtained in an operating range from 70 Pa to 10 kPa. Since the method primarily uses a microfluidic sealed chamber, it does not require additional fabrication steps and may easily be incorporated in several lab-on-a-chip fluidic applications for laminar as well as turbulent flow conditions.

  17. Pressure Drop in Radiator Air Tubes

    NASA Technical Reports Server (NTRS)

    Parsons, S R

    1921-01-01

    This report describes a method for measuring the drop in static pressure of air flowing through a radiator and shows (1) a reason for the discrepancy noted by various observers between head resistance and drop in pressure; (2) a difference in degree of contraction of the jet in entering a circular cell and a square cell; (3) the ratio of internal frictional resistance to total head resistance for two representative types; (4) the effect of smoothness of surface on pressure gradient; and (5) the effects of supplying heat to the radiator on pressure gradient. The fact that the pressure gradients are found to be approximately proportional to the square of the rate of flow of air appears to indicate turbulent flow, even in the short tubes of the radiator. It was found that the drop in the static pressure in the air stream through a cellular radiator and the pressure gradient in the air tubes are practically proportional to the square of the air flow in a given air density; that the difference between the head resistance per unit area and the fall of static pressure through the air tubes in radiators is apparent rather than real; and that radiators of different types differ widely in the amount of contraction of the jet at entrance. The frictional resistance was found to vary considerably, and in one case to be two-thirds of the head resistance in the type using circular cells and one-half of the head resistance of the radiator type using square cells of approximately the same dimensions.

  18. Building pressurization control with rooftop air conditioners

    SciTech Connect

    Winter, S.

    1982-10-01

    The modulated exhaust fan appears to be the most cost effective positive means to maintain close building pressure control with rooftop air conditioning, but because building construction and applications vary, every building's pressure control needs must be analyzed. Requirements will vary from no relief to barometric dampers to return fans to modulated exhaust fans. As heating and cooling costs continue to rise and tighter building codes prevail, proper selection of building pressure control is one area that must be monitored more carefully by the HVAC system designer.

  19. Simple Experiments for Teaching Air Pressure

    ERIC Educational Resources Information Center

    Shamsipour, Gholamreza

    2006-01-01

    Everyone who teaches physics knows very well that sometimes a simple device or experiment can help to make a concept clear. In this paper, inspired by "The Jumping Pencil" by Martin Gardner, I will discuss a simple demonstration device that can be used to start the study of air pressure.

  20. Differential absorption lidar measurements of atmospheric temperature and pressure profiles

    NASA Technical Reports Server (NTRS)

    Korb, C. L.

    1981-01-01

    The theory and methodology of using differential absorption lidar techniques for the remote measurement of atmospheric pressure profiles, surface pressure, and temperature profiles from ground, air, and space-based platforms are presented. Pressure measurements are effected by means of high resolution measurement of absorption at the edges of the oxygen A band lines where absorption is pressure dependent due to collisional line broadening. Temperature is assessed using measurements of the absorption at the center of the oxygen A band line originating from a quantum state with high ground state energy. The population of the state is temperature dependent, allowing determination of the temperature through the Boltzmann term. The results of simulations of the techniques using Voigt profile and variational analysis are reported for ground-based, airborne, and Shuttle-based systems. Accuracies in the 0.5-1.0 K and 0.1-0.3% range are projected.

  1. High pressure microhollow cathode discharges in air

    SciTech Connect

    Khedr, M.A.; Stark, R.H.; Watson, B.; Schoenbach, K.H.

    1998-12-31

    Research on high pressure, large volume glow discharges in air is motivated by applications such as reflectors and absorbers for electromagnetic radiation, plasma processing, and the remediation of gaseous pollution. In order to prevent glow-to-arc transitions, which in high-pressure glow discharges start in the cathode region, it is proposed to use a plasma cathode consisting of an array of microhollow cathode discharges. To explore the conditions for stable operation of single 100 {micro}m microhollow cathode discharges in flowing air, the current-voltage characteristics, and the visual appearance of a 100 {micro}m microhollow cathode discharge were studied. The results show that the threshold current for the transition from a glow into a filamentary discharge varies inversely with pressure. At pressures of 400 Torr the current in the 100 {micro}m hollow cathode discharge must not exceed 0.5 mA in order for the discharge to be stable. The type of instability, which causes the transition from dc to fluctuating currents, is not known at this time, but the observed dependence of the threshold current from the gas pressure points to a thermal instability. Assuming that the White-Allis scaling law still holds for air discharges at pressures close to atmospheric, it is expected that reducing the cathode hole diameter to 50 {micro}m will allow us to operate microhollow cathode discharges at atmospheric air with currents of up to 0.25 mA. Experimental studies on the effect of the cathode dimensions and cathode material are underway and results will be discussed at the conference.

  2. Intraoral air pressure and oral air flow under different bleed and bite-block conditions.

    PubMed

    Putnam, A H; Shelton, R L; Kastner, C U

    1986-03-01

    Intraoral pressures and oral flows were measured as normal talkers produced /p lambda/ and /si/ under experimental conditions that perturbed the usual aeromechanical production characteristics of the consonants. A translabial pressure-release device was used to bleed off intraoral pressure during /p/. Bite-blocks were used to open the anterior bite artificially during /s/. For /p/, intraoral pressure decreased and translabial air leakage increased as bleed orifice area increased. For /s/, flow increased as the area of sibilant constriction increased, but differential pressure across the /s/ oral constriction did not vary systematically with changes in its area. Flow on postconsonantal vowels /lambda/ and /i/ did not vary systematically across experimental conditions. The data imply that maintenance of perturbed intraoral pressure was more effective when compensatory options included opportunity for increased respiratory drive and structural adjustments at the place of consonant articulation rather than increased respiratory drive alone.

  3. 21 CFR 868.2875 - Differential pressure transducer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Differential pressure transducer. 868.2875 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2875 Differential pressure transducer. (a) Identification. A differential pressure transducer is a two-chambered device intended...

  4. 21 CFR 868.2875 - Differential pressure transducer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Differential pressure transducer. 868.2875 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2875 Differential pressure transducer. (a) Identification. A differential pressure transducer is a two-chambered device intended...

  5. 21 CFR 868.2875 - Differential pressure transducer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Differential pressure transducer. 868.2875 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2875 Differential pressure transducer. (a) Identification. A differential pressure transducer is a two-chambered device intended...

  6. 21 CFR 868.2875 - Differential pressure transducer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Differential pressure transducer. 868.2875 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2875 Differential pressure transducer. (a) Identification. A differential pressure transducer is a two-chambered device intended...

  7. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Alternating pressure air flotation mattress. 880... Personal Use Therapeutic Devices § 880.5550 Alternating pressure air flotation mattress. (a) Identification. An alternating pressure air flotation mattress is a device intended for medical purposes...

  8. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Alternating pressure air flotation mattress. 880... Personal Use Therapeutic Devices § 880.5550 Alternating pressure air flotation mattress. (a) Identification. An alternating pressure air flotation mattress is a device intended for medical purposes...

  9. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Alternating pressure air flotation mattress. 880... Personal Use Therapeutic Devices § 880.5550 Alternating pressure air flotation mattress. (a) Identification. An alternating pressure air flotation mattress is a device intended for medical purposes...

  10. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Alternating pressure air flotation mattress. 880... Personal Use Therapeutic Devices § 880.5550 Alternating pressure air flotation mattress. (a) Identification. An alternating pressure air flotation mattress is a device intended for medical purposes...

  11. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Alternating pressure air flotation mattress. 880... Personal Use Therapeutic Devices § 880.5550 Alternating pressure air flotation mattress. (a) Identification. An alternating pressure air flotation mattress is a device intended for medical purposes...

  12. Intraoral Air Pressure of Alaryngeal Speakers during a No-Air Insufflation Maneuver.

    ERIC Educational Resources Information Center

    Gorham, Mary M.; And Others

    1996-01-01

    Intraoral air pressure was recorded during the production of consonant cognate pairs by 8 esophageal speakers (mean age 67 years) under 2 experimental conditions: after the insufflation of air and without air insufflation. Results revealed that peak intraoral air pressure magnitudes were significantly greater following the insufflation of air than…

  13. Differential pressure sensing system for airfoils usable in turbine engines

    DOEpatents

    Yang, Wen-Ching; Stampahar, Maria E.

    2005-09-13

    A detection system for identifying airfoils having a cooling systems with orifices that are plugged with contaminants or with showerheads having a portion burned off. The detection system measures pressures at different locations and calculates or measures a differential pressure. The differential pressure may be compared with a known benchmark value to determine whether the differential pressure has changed. Changes in the differential pressure may indicate that one or more of the orifices in a cooling system of an airfoil are plugged or that portions of, or all of, a showerhead has burned off.

  14. Autoimmune regulator, Aire, is a novel regulator of chondrocyte differentiation.

    PubMed

    Si, Yuan; Inoue, Kazuki; Igarashi, Katsuhide; Kanno, Jun; Imai, Yuuki

    2013-08-01

    Chondrocyte differentiation is controlled by various regulators, such as Sox9 and Runx2, but the process is complex. To further understand the precise underlying molecular mechanisms of chondrocyte differentiation, we aimed to identify a novel regulatory factor of chondrocyte differentiation using gene expression profiles of micromass-cultured chondrocytes at different differentiation stages. From the results of microarray analysis, the autoimmune regulator, Aire, was identified as a novel regulator. Aire stable knockdown cells, and primary cultured chondrocytes obtained from Aire(-/-) mice, showed reduced mRNA expression levels of chondrocyte-related genes. Over-expression of Aire induced the early stages of chondrocyte differentiation by facilitating expression of Bmp2. A ChIP assay revealed that Aire was recruited on an Airebinding site (T box) in the Bmp2 promoter region in the early stages of chondrocyte differentiation and histone methylation was modified. These results suggest that Aire can facilitate early chondrocyte differentiation by expression of Bmp2 through altering the histone modification status of the promoter region of Bmp2. Taken together, Aire might play a role as an active regulator of chondrocyte differentiation, which leads to new insights into the regulatory mechanisms of chondrocyte differentiation.

  15. Modelling of air pressure effects in casting moulds

    NASA Astrophysics Data System (ADS)

    Attar, E.; Homayonifar, P.; Babaei, R.; Asgari, K.; Davami, P.

    2005-09-01

    In the casting process, as a mould is filled with molten metal, air escapes through the vents. Air pressure in the mould cavity has serious effects upon the filling behaviour such as surface profile of the molten metal and filling time. In this project a computational model was developed for calculation of air pressure during the mould filling. A 3D single phase code based on the SOLA-VOF algorithm was used for the prediction of the fluid flow. The ideal gas assumption, conservation of mass equation and Bernoulli law were used for the calculation of air pressure. A new algorithm was developed to interpolate air pressure on the surface cells. The creation of air pressure was correlated with the sizes of the vents and their locations. An experimental test was designed to verify the modelling results. Comparison between the experimental data and simulation results has shown a good agreement.

  16. Noncontact Monitoring of Respiration by Dynamic Air-Pressure Sensor.

    PubMed

    Takarada, Tohru; Asada, Tetsunosuke; Sumi, Yoshihisa; Higuchi, Yoshinori

    2015-01-01

    We have previously reported that a dynamic air-pressure sensor system allows respiratory status to be visually monitored for patients in minimally clothed condition. The dynamic air-pressure sensor measures vital information using changes in air pressure. To utilize this device in the field, we must clarify the influence of clothing conditions on measurement. The present study evaluated use of the dynamic air-pressure sensor system as a respiratory monitor that can reliably detect change in breathing patterns irrespective of clothing. Twelve healthy volunteers reclined on a dental chair positioned horizontally with the sensor pad for measuring air-pressure signals corresponding to respiration placed on the seat back of the dental chair in the central lumbar region. Respiratory measurements were taken under 2 conditions: (a) thinly clothed (subject lying directly on the sensor pad); and (b) thickly clothed (subject lying on the sensor pad covered with a pressure-reducing sheet). Air-pressure signals were recorded and time integration values for air pressure during each expiration were calculated. This information was compared with expiratory tidal volume measured simultaneously by a respirometer connected to the subject via face mask. The dynamic air-pressure sensor was able to receive the signal corresponding to respiration regardless of clothing conditions. A strong correlation was identified between expiratory tidal volume and time integration values for air pressure during each expiration for all subjects under both clothing conditions (0.840-0.988 for the thinly clothed condition and 0.867-0.992 for the thickly clothed condition). These results show that the dynamic air-pressure sensor is useful for monitoring respiratory physiology irrespective of clothing.

  17. Noncontact Monitoring of Respiration by Dynamic Air-Pressure Sensor

    PubMed Central

    Takarada, Tohru; Asada, Tetsunosuke; Sumi, Yoshihisa; Higuchi, Yoshinori

    2015-01-01

    We have previously reported that a dynamic air-pressure sensor system allows respiratory status to be visually monitored for patients in minimally clothed condition. The dynamic air-pressure sensor measures vital information using changes in air pressure. To utilize this device in the field, we must clarify the influence of clothing conditions on measurement. The present study evaluated use of the dynamic air-pressure sensor system as a respiratory monitor that can reliably detect change in breathing patterns irrespective of clothing. Twelve healthy volunteers reclined on a dental chair positioned horizontally with the sensor pad for measuring air-pressure signals corresponding to respiration placed on the seat back of the dental chair in the central lumbar region. Respiratory measurements were taken under 2 conditions: (a) thinly clothed (subject lying directly on the sensor pad); and (b) thickly clothed (subject lying on the sensor pad covered with a pressure-reducing sheet). Air-pressure signals were recorded and time integration values for air pressure during each expiration were calculated. This information was compared with expiratory tidal volume measured simultaneously by a respirometer connected to the subject via face mask. The dynamic air-pressure sensor was able to receive the signal corresponding to respiration regardless of clothing conditions. A strong correlation was identified between expiratory tidal volume and time integration values for air pressure during each expiration for all subjects under both clothing conditions (0.840–0.988 for the thinly clothed condition and 0.867–0.992 for the thickly clothed condition). These results show that the dynamic air-pressure sensor is useful for monitoring respiratory physiology irrespective of clothing. PMID:26398125

  18. Pressurized solid oxide fuel cell integral air accumular containment

    DOEpatents

    Gillett, James E.; Zafred, Paolo R.; Basel, Richard A.

    2004-02-10

    A fuel cell generator apparatus contains at least one fuel cell subassembly module in a module housing, where the housing is surrounded by a pressure vessel such that there is an air accumulator space, where the apparatus is associated with an air compressor of a turbine/generator/air compressor system, where pressurized air from the compressor passes into the space and occupies the space and then flows to the fuel cells in the subassembly module, where the air accumulation space provides an accumulator to control any unreacted fuel gas that might flow from the module.

  19. The influence of locomotion on air-sac pressures in little penguins.

    PubMed

    Boggs, D F; Baudinette, R V; Frappell, P B; Butler, P J

    2001-10-01

    Air-sac pressures have been reported to oscillate with wing beat in flying magpies and with foot paddling in diving ducks. We sought to determine the impact on air-sac pressure of wing beats during swimming and of the step cycle during walking in little penguins (Eudyptula minor). Fluctuations averaged 0.16+/-0.06 kPa in the interclavicular air sacs, but only 0.06+/-0.04 kPa in the posterior thoracic sac, generating a small differential pressure between sacs of 0.06+/-0.02 kPa (means +/- S.E.M., N=4). These fluctuations occurred at approximately 3 Hz and corresponded to wing beats during swimming, indicated by electromyograms from the pectoralis and supracoracoideus muscles. There was no abdominal muscle activity associated with swimming or exhalation, but the abdominal muscles were active with the step cycle in walking penguins, and oscillations in posterior air-sac pressure (0.08+/-0.038 kPa) occurred with steps. We conclude that high-frequency oscillations in differential air-sac pressure enhance access to and utilization of the O(2) stores in the air sacs during a dive. PMID:11707507

  20. Plant responses to reduced air pressure: advanced techniques and results

    NASA Astrophysics Data System (ADS)

    Daunicht, H.-J.; Brinkjans, H. J.

    1996-01-01

    Knowledge on air pressure impacts on plant processes and growth is essential for understanding responses to altitude and for comprehending the way of action of aerial gasses in general, and is of potential importance for life support systems in space. Our research on reduced air pressure was extended by help of a new set-up comprising two constantly ventilated chambers (283 L each), allowing pressure gradients of +/- 100 kPa. They provide favourable general growth conditions while maintaining all those factors constant or at desired levels which modify the action of air pressure, e.g. water vapour pressure deficit and air mass flow over the plants. Besides plant growth parameters, transpiration and CO_2 gas exchange are determined continuously. Results are presented on young tomato plants grown hydroponically, which had been treated with various combinations of air pressure (400 - 700 - 1000 hPa), CO_2 concentration and wind intensity for seven days. At the lowest pressure transpiration was enhanced considerably, and the plants became sturdier. On the other hand growth was retarded to a certain extent, attributable to secondary air pressure effects. Therefore, even greater limitations of plant productivity are expected after more extended periods of low pressure treatment.

  1. A Balanced-pressure Sliding Seal for Transfer of Pressurized Air Between Stationary and Rotating Parts

    NASA Technical Reports Server (NTRS)

    Curren, Arthur N; Cochran, Reeves P

    1957-01-01

    A combination sliding-ring and pressure-balancing seal capable of transferring pressurize air from stationary to rotating parts was developed and experimentally investigated at sliding velocities and cooling-air pressures up to 10,000 feet per minute and 38.3 pounds per square inch absolute, respectively. Leakage of cooling air was completely eliminated with an expenditure of balance air less than one-fourth the leakage loss of air from labyrinth seals under the same conditions. Additional cooling of the carbon-base seal rings was required, and the maximum wear rate on the rings was about 0.0005 inch per hour.

  2. A beam-membrane structure micromachined differential pressure flow sensor.

    PubMed

    Chen, P; Zhao, Y L; Tian, B; Li, C; Li, Y Y

    2015-04-01

    A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

  3. A beam-membrane structure micromachined differential pressure flow sensor

    SciTech Connect

    Chen, P.; Zhao, Y. L.; Tian, B. Li, C.; Li, Y. Y.

    2015-04-15

    A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

  4. Measurement of the differential pressure of liquid metals

    DOEpatents

    Metz, H.J.

    1975-09-01

    This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed. (auth)

  5. The relationships between air exposure, negative pressure, and hemolysis.

    PubMed

    Pohlmann, Joshua R; Toomasian, John M; Hampton, Claire E; Cook, Keith E; Annich, Gail M; Bartlett, Robert H

    2009-01-01

    The purpose of this study was to describe the hemolytic effects of both negative pressure and an air-blood interface independently and in combination in an in vitro static blood model. Samples of fresh ovine or human blood (5 ml) were subjected to a bubbling air interface (0-100 ml/min) or negative pressure (0-600 mm Hg) separately, or in combination, for controlled periods of time and analyzed for hemolysis. Neither negative pressure nor an air interface alone increased hemolysis. However, when air and negative pressure were combined, hemolysis increased as a function of negative pressure, the air interface, and time. Moreover, when blood samples were exposed to air before initiating the test, hemolysis was four to five times greater than samples not preexposed to air. When these experiments were repeated using freshly drawn human blood, the same phenomena were observed, but the hemolysis was significantly higher than that observed in sheep blood. In this model, hemolysis is caused by combined air and negative pressure and is unrelated to either factor alone.

  6. Air plasma jet with hollow electrodes at atmospheric pressure

    SciTech Connect

    Hong, Yong Cheol; Uhm, Han Sup

    2007-05-15

    Atmospheric-pressure plasma jet with air is produced through hollow electrodes and dielectric with a hole of 1 mm diam. The plasma jet device is operated by injecting pressurized air into the electrode hole. The air plasma jet device at average powers less than 5 W exhibits a cold plasma jet of about 2 cm in length and near the room temperature, being low enough to treat thermally sensitive materials. Preliminary studies on the discharge characteristics and application tests are also presented by comparing the air plasma jet with the nitrogen and argon plasma jet.

  7. Air circulation under reduced atmospheric pressures

    NASA Astrophysics Data System (ADS)

    Hillhouse, Lendell E.

    The control of heat exchange is vital for plant life in off-world, low pressure, greenhouses. The ability to control this process was limited by methodology and technology. Mathematical models, based on classical mechanics are created to enhance our control capabilities. Data is collected using various sensors placed inside the Low Pressure Test Bed (LPTB) Chamber at Kennedy Space Center. Data from those sensors became non-linear at various pressures below 25 kPa. We introduced mathematical calibration corrections and found that sensor data linearity could be extended to a greater range of pressures. These calibration corrections allow for sensor calibration corrections in operational environments that differ from the environment of calibration (normal Earth atmospheric pressure).

  8. Constant-Differential-Pressure Two-Fluid Accumulator

    NASA Technical Reports Server (NTRS)

    Piecuch, Benjamin; Dalton, Luke T.

    2010-01-01

    A two-fluid accumulator has been designed, built, and demonstrated to provide an acceptably close approximation to constant differential static pressure between two fluids over the full ranges of (1) accumulator stroke, (2) rates of flow of the fluids, and (3) common static pressure applied to the fluids. Prior differential- pressure two-fluid accumulators are generally not capable of maintaining acceptably close approximations to constant differential pressures. The inadequacies of a typical prior differential-pressure two-fluid accumulator can be summarized as follows: The static differential pressure is governed by the intrinsic spring rate (essentially, the stiffness) of an accumulator tank. The spring rate can be tailored through selection of the tank-wall thickness, selection of the number and/or shape of accumulator convolutions, and/or selection of accumulator material(s). Reliance on the intrinsic spring rate of the tank results in three severe limitations: (1) The spring rate and the expulsion efficiency tend to be inversely proportional to each other: that is to say, as the stiffness (and thus the differential pressure) is increased, the range of motion of the accumulator is reduced. (2) As the applied common static pressure increases, the differential pressure tends to decrease. An additional disadvantage, which may or may not be considered limiting, depending on the specific application, is that an increase in stiffness entails an increase in weight. (3) The additional weight required by a low expulsion efficiency accumulator eliminates the advantage given to such gas storage systems. The high expulsion efficiency provided by this two-fluid accumulator allows for a lightweight, tightly packaged system, which can be used in conjunction with a fuel cell-based system.

  9. Laboratory performance of alternating pressure air mattresses component and sequelae.

    PubMed

    Bain, Duncan

    The performance of three different alternating pressure air mattresses with different geometries of air cell were compared (Nimbus 3, Heritage, Tamora Plus), using simple performance indices based on pressure mapping. The aim of this study was to examine the effect on performance of elevating the backrest and thigh section of the bed into sitting position. Ten healthy volunteers of various sizes were pressure-mapped over the full pressure cycle on three alternating pressure air mattresseses with differing cell geometries. This was then repeated with the beds profiled to a sitting position. Performance of the alternating pressure air mattresses in terms of their ability to redistribute pressure dynamically was assessed in the different positions. The different alternating pressure air mattresses performed similarly with the bed in the lying flat position, but smaller cells appeared to be more effective in the sitting position. A conclusion was made that cell geometry may have an effect on the ability of the mattress to achieve alternating behaviour in the sitting position.

  10. 58. AIR PRESSURIZATION TANK BEING LIFTED INTO PLACE ON THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    58. AIR PRESSURIZATION TANK BEING LIFTED INTO PLACE ON THE VAL BRIDGE STRUCTURE AT ISLIP CANYON, April 9, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  11. 27. EXTENSION OF SURGE CHAMBER AND AIR PIPES TO PRESSURE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. EXTENSION OF SURGE CHAMBER AND AIR PIPES TO PRESSURE LINE, HIGHLINE PUMPING PLANT. December 11, 1920 - Highline Canal & Pumping Station, South side of Salt River between Tempe, Phoenix & Mesa, Tempe, Maricopa County, AZ

  12. Influence of ambient air pressure on effervescent atomization

    NASA Technical Reports Server (NTRS)

    Chen, S. K.; Lefebvre, A. H.; Rollbuhler, J.

    1993-01-01

    The influence of ambient air pressure on the drop-size distributions produced in effervescent atomization is examined in this article. Also investigated are the effects on spray characteristics of variations in air/liquid mass ratio, liquid-injection pressure, and atomizer discharge-orifice diameter at different levels of ambient air pressure. It is found that continuous increase in air pressure above the normal atmospheric value causes the mean drop-size to first increase up to a maximum value and then decline. An explanation for this characteristic is provided in terms of the various contributing factors to the overall atomization process. It is also observed that changes in atomizer geometry and operating conditions have little effect on the distribution of drop-sizes in the spray.

  13. 21 CFR 868.2875 - Differential pressure transducer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Differential pressure transducer. 868.2875 Section 868.2875 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2875 Differential...

  14. Method and Apparatus for Measuring Surface Air Pressure

    NASA Technical Reports Server (NTRS)

    Lin, Bing (Inventor); Hu, Yongxiang (Inventor)

    2014-01-01

    The present invention is directed to an apparatus and method for remotely measuring surface air pressure. In one embodiment, the method of the present invention utilizes the steps of transmitting a signal having multiple frequencies into the atmosphere, measuring the transmitted/reflected signal to determine the relative received power level of each frequency and then determining the surface air pressure based upon the attenuation of the transmitted frequencies.

  15. [A new approach to improving air in habitable pressurized modules].

    PubMed

    Argunova, A M; Odelevskiĭ, V K; Strogonova, L B

    2009-01-01

    Habitable pressurized modules, including space cabin, should provide ecologically efficient and physiologically auspicious conditions. The regenerated air should be comparable with fresh air of the natural environment humans belonged with over thousand years of evolution. Air scrubbing system GALOINHALATOR IGK-02 (MAI, patent No. 2209093) comprises eco-pure minerals from the salt rocks in Verkhnekamsk (the Urals). The portable automatic system controls air saturation with negative light aeroions and fine salt aerosols at preset levels. The laboratory, clinical and model tests demonstrated bactericide and bacteriostatic effects of air produced by GALOINHALATOR and the mineral ability to adsorb harmful volatile admixtures. Breathing decontaminated and ionized air during long stay in a pressurized module is beneficial to human performance, immunity, and chronic diseases prevention. PMID:19621806

  16. Teaching Science: Air Pressure "Eggs-periments."

    ERIC Educational Resources Information Center

    Leyden, Michael B.

    1994-01-01

    Discusses how teachers can introduce students to various scientific concept concerning motion, air composition, and heat by conducting an experiment: A peeled, hard-boiled egg is sucked into a bottle neck slightly smaller than the egg, after the bottle has been filled and emptied of hot water. Also discusses how students' understanding of the…

  17. Pressure of air on coming to rest from various speeds

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1927-01-01

    The text gives theoretical formulas from which is computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. Pressure graphs are given for speeds from 1 cm. Sec. up to those of swift projectiles.

  18. System for measuring multiphase flow using multiple pressure differentials

    DOEpatents

    Fincke, James R.

    2003-01-01

    An improved method and system for measuring a multi-phase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multi-phase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The system for determining the mass flow of the high void fraction fluid flow and the gas flow includes taking into account a pressure drop experienced by the gas phase due to work performed by the gas phase in accelerating the liquid phase.

  19. Controlled differential pressure system for an enhanced fluid blending apparatus

    DOEpatents

    Hallman, Jr., Russell Louis

    2009-02-24

    A system and method for producing a controlled blend of two or more fluids. Thermally-induced permeation through a permeable tube is used to mix a first fluid from outside the tube with a second fluid flowing through the tube. Mixture ratios may be controlled by adjusting the temperature of the first fluid or by adjusting the pressure drop through the permeable tube. The combination of a back pressure control valve and a differential regulator is used to control the output pressure of the blended fluid. The combination of the back pressure control valve and differential regulator provides superior flow control of the second dry gas. A valve manifold system may be used to mix multiple fluids, and to adjust the volume of blended fluid produced, and to further modify the mixture ratio.

  20. Air-to-air combat analysis - Review of differential-gaming approaches

    NASA Technical Reports Server (NTRS)

    Ardema, M. D.

    1981-01-01

    The problem of evaluating the combat performance of fighter/attack aircraft is discussed, and the mathematical nature of the problem is examined. The following approaches to air combat analysis are reviewed: (1) differential-turning differential game and (2) coplanar differential game. Selected numerical examples of these approaches are presented. The relative advantages and disadvantages of each are analyzed, and it is concluded that air combat analysis is an extremely difficult mathematical problem and that no one method of approach is best for all purposes. The paper concludes with a discussion of how the two approaches might be used in a complementary manner.

  1. Fuel Cells Utilizing Oxygen From Air at Low Pressures

    NASA Technical Reports Server (NTRS)

    Cisar, Alan; Boyer, Chris; Greenwald, Charles

    2006-01-01

    A fuel cell stack has been developed to supply power for a high-altitude aircraft with a minimum of air handling. The fuel cell is capable of utilizing oxygen from ambient air at low pressure with no need for compression. For such an application, it is advantageous to take oxygen from the air (in contradistinction to carrying a supply of oxygen onboard), but it is a challenging problem to design a fuel-cell stack of reasonable weight that can generate sufficient power while operating at reduced pressures. The present fuel-cell design is a response to this challenge. The design features a novel bipolar plate structure in combination with a gas-diffusion structure based on a conductive metal core and a carbon gas-diffusion matrix. This combination makes it possible for the flow fields in the stack to have a large open fraction (ratio between open volume and total volume) to permit large volumes of air to flow through with exceptionally low backpressure. Operations at reduced pressure require a corresponding increase in the volume of air that must be handled to deliver the same number of moles of oxygen to the anodes. Moreover, the increase in the open fraction, relative to that of a comparable prior fuel-cell design, reduces the mass of the stack. The fuel cell has been demonstrated to operate at a power density as high as 105 W/cm2 at an air pressure as low as 2 psia (absolute pressure 14 kPa), which is the atmospheric pressure at an altitude of about 50,000 ft ( 15.2 km). The improvements in the design of this fuel cell could be incorporated into designs of other fuel cells to make them lighter in weight and effective at altitudes higher than those of prior designs. Potential commercial applications for these improvements include most applications now under consideration for fuel cells.

  2. Inverse Association between Air Pressure and Rheumatoid Arthritis Synovitis

    PubMed Central

    Furu, Moritoshi; Nakabo, Shuichiro; Ohmura, Koichiro; Nakashima, Ran; Imura, Yoshitaka; Yukawa, Naoichiro; Yoshifuji, Hajime; Matsuda, Fumihiko; Ito, Hiromu; Fujii, Takao; Mimori, Tsuneyo

    2014-01-01

    Rheumatoid arthritis (RA) is a bone destructive autoimmune disease. Many patients with RA recognize fluctuations of their joint synovitis according to changes of air pressure, but the correlations between them have never been addressed in large-scale association studies. To address this point we recruited large-scale assessments of RA activity in a Japanese population, and performed an association analysis. Here, a total of 23,064 assessments of RA activity from 2,131 patients were obtained from the KURAMA (Kyoto University Rheumatoid Arthritis Management Alliance) database. Detailed correlations between air pressure and joint swelling or tenderness were analyzed separately for each of the 326 patients with more than 20 assessments to regulate intra-patient correlations. Association studies were also performed for seven consecutive days to identify the strongest correlations. Standardized multiple linear regression analysis was performed to evaluate independent influences from other meteorological factors. As a result, components of composite measures for RA disease activity revealed suggestive negative associations with air pressure. The 326 patients displayed significant negative mean correlations between air pressure and swellings or the sum of swellings and tenderness (p = 0.00068 and 0.00011, respectively). Among the seven consecutive days, the most significant mean negative correlations were observed for air pressure three days before evaluations of RA synovitis (p = 1.7×10−7, 0.00027, and 8.3×10−8, for swellings, tenderness and the sum of them, respectively). Standardized multiple linear regression analysis revealed these associations were independent from humidity and temperature. Our findings suggest that air pressure is inversely associated with synovitis in patients with RA. PMID:24454853

  3. Air plasma jet with hollow electrodes at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Hong, Yong Cheol; Uhm, Han Sup

    2007-05-01

    Atmospheric-pressure plasma jet with air is produced through hollow electrodes and dielectric with a hole of 5W exhibits a cold plasma jet of about 2cm in length and near the room temperature, being low enough to treat thermally sensitive materials. Preliminary studies on the discharge characteristics and application tests are also presented by comparing the air plasma jet with the nitrogen and argon plasma jet.

  4. Temperature and pressure influence on explosion pressures of closed vessel propane-air deflagrations.

    PubMed

    Razus, Domnina; Brinzea, Venera; Mitu, Maria; Oancea, Dumitru

    2010-02-15

    An experimental study on pressure evolution during closed vessel explosions of propane-air mixtures was performed, for systems with various initial concentrations and pressures ([C(3)H(8)]=2.50-6.20 vol.%, p(0)=0.3-1.2 bar). The explosion pressures and explosion times were measured in a spherical vessel (Phi=10 cm), at various initial temperatures (T(0)=298-423 K) and in a cylindrical vessel (Phi=10 cm; h=15 cm), at ambient initial temperature. The experimental values of explosion pressures are examined against literature values and compared to adiabatic explosion pressures, computed by assuming chemical equilibrium within the flame front. The influence of initial pressure, initial temperature and fuel concentration on explosion pressures and explosion times are discussed. At constant temperature and fuel/oxygen ratio, the explosion pressures are linear functions of total initial pressure, as reported for other fuel-air mixtures. At constant initial pressure and composition, both the measured and calculated (adiabatic) explosion pressures are linear functions of reciprocal value of initial temperature. Such correlations are extremely useful for predicting the explosion pressures of flammable mixtures at elevated temperatures and/or pressures, when direct measurements are not available.

  5. Differential-pressure-based fiber-optic temperature sensor using Fabry-Perot interferometry.

    PubMed

    Liu, Tiegen; Yin, Jinde; Jiang, Junfeng; Liu, Kun; Wang, Shuang; Zou, Shengliang

    2015-03-15

    We propose a novel fiber-optic Fabry-Perot interferometric (FFPI) temperature sensor based on differential pressure resulting from thermal expansion of sealed air. A thin silicon diaphragm is sandwiched between two micro-circular cavity-structured Pyrex plates to construct a FP and an air cavity. The thermal expansion of sealed air induces differential pressure variation between cavities and thus the deformation of thin diaphragm, which transfers temperature change into cavity length shift of FP interferometer. Theory analysis results indicate that the temperature-sensitivity can be designed flexibly by choosing the parameters of radius and thickness of silicon diaphragm, and the differential pressure between two cavities. Experimental results demonstrate that the temperature sensitivity of 6.07 nm/°C is achieved with the resolution of 0.10°C under the range of -50°C to 100°C, and the response time is around 1.3 s with temperature change from 28°C to 100°C. PMID:25768179

  6. Optical zero-differential pressure switch and its evaluation in a multiple pressure measuring system

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1977-01-01

    The design of a clamped-diaphragm pressure switch is described in which diaphragm motion is detected by a simple fiber-optic displacement sensor. The switch was evaluated in a pressure measurement system where it detected the zero crossing of the differential pressure between a static test pressure and a tank pressure that was periodically ramped from near zero to fullscale gage pressure. With a ramping frequency of 1 hertz and a full-scale tank pressure of 69 N/sq cm gage (100 psig), the switch delay was as long as 2 milliseconds. Pressure measurement accuracies were 0.25 to 0.75 percent of full scale. Factors affecting switch performance are also discussed.

  7. Tongue-Palate Contact Pressure, Oral Air Pressure, and Acoustics of Clear Speech

    ERIC Educational Resources Information Center

    Searl, Jeff; Evitts, Paul M.

    2013-01-01

    Purpose: The authors compared articulatory contact pressure (ACP), oral air pressure (Po), and speech acoustics for conversational versus clear speech. They also assessed the relationship of these measures to listener perception. Method: Twelve adults with normal speech produced monosyllables in a phrase using conversational and clear speech.…

  8. DEVELOPMENT OF A LOW PRESSURE, AIR ATOMIZED OIL BURNER WITH HIGH ATOMIZER AIR FLOW

    SciTech Connect

    BUTCHER,T.A.

    1998-01-01

    This report describes technical advances made to the concept of a low pressure, air atomized oil burner for home heating applications. Currently all oil burners on the market are of the pressure atomized, retention head type. These burners have a lower firing rate limit of about 0.5 gallons per hour of oil, due to reliability problems related to small flow passage sizes. High pressure air atomized burners have been shown to be one route to avoid this problem but air compressor cost and reliability have practically eliminated this approach. With the low pressure air atomized burner the air required for atomization can be provided by a fan at 5--8 inches of water pressure. A burner using this concept, termed the Fan-Atomized Burner or FAB has been developed and is currently being commercialized. In the head of the FAB, the combustion air is divided into three parts, much like a conventional retention head burner. This report describes development work on a new concept in which 100% of the air from the fan goes through the atomizer. The primary advantage of this approach is a great simplification of the head design. A nozzle specifically sized for this concept was built and is described in the report. Basic flow pressure tests, cold air velocity profiles, and atomization performance have been measured. A burner head/flame tube has been developed which promotes a torroidal recirculation zone near the nozzle for flame stability. The burner head has been tested in several furnace and boiler applications over the tiring rate range 0.2 to 0.28 gallons per hour. In all cases the burner can operate with very low excess air levels (under 10%) without producing smoke. Flue gas NO{sub x} concentration varied from 42 to 62 ppm at 3% 0{sub 2}. The concept is seen as having significant potential and planned development efforts are discussed.

  9. Multi-hole pressure probes to air data system for subsonic small-scale air vehicles

    NASA Astrophysics Data System (ADS)

    Shevchenko, A. M.; Berezin, D. R.; Puzirev, L. N.; Tarasov, A. Z.; Kharitonov, A. M.; Shmakov, A. S.

    2016-10-01

    A brief review of research performed to develop multi-hole probes to measure of aerodynamic angles, dynamic head, and static pressure of a flying vehicle. The basis of these works is the application a well-known classical multi-hole pressure probe technique of measuring of a 3D flow to use in the air data system. Two multi-hole pressure probes with spherical and hemispherical head to air-data system for subsonic small-scale vehicles have been developed. A simple analytical probe model with separation of variables is proposed. The probes were calibrated in the wind tunnel, one of them is in-flight tested.

  10. Modeling of an air-backed diaphragm in dynamic pressure sensors: Effects of the air cavity

    NASA Astrophysics Data System (ADS)

    Liu, Haijun; Olson, Douglas A.; Yu, Miao

    2014-12-01

    As the key structure of most dynamic pressure sensors, a diaphragm backed by an air cavity plays a critical role in the determination of sensor performance metrics. In this paper, we investigate the influence of air cavity length on the sensitivity and bandwidth. A continuum mechanics model neglecting the air viscous effect is first developed to capture the structural-acoustic coupling between a clamped circular diaphragm and a cylindrical backing air cavity. To facilitate sensor design, close-form approximations are obtained to calculate the static sensitivity and the fundamental natural frequency of the air-backed diaphragm. Parametric studies based on this analytical model show that the air cavity can change both the effective mass and the effective stiffness of the diaphragm. One new finding is that the natural frequency of the air-backed diaphragm behaves differently in three different cavity length ranges. In particular, due to the mass effect of the air cavity being dominant, it is shown for the first time that the natural frequency decreases when the cavity length decreases below a critical value in the short cavity range. Furthermore, a finite element method (FEM) model is developed to validate the continuum mechanics model and to study the damping effect of the air cavity. These results provide important design guidelines for dynamic pressure sensors with air-backed diaphragms.

  11. The Jar Magic--Instructional Activities for Teaching Air Pressure

    ERIC Educational Resources Information Center

    Ku, Bing-Hong; Chen, Chyong-Sun

    2013-01-01

    There are a variety of impressive activities designed for teaching the concept of air pressure to junior high school students. Water, glasses, balloons, plastic bottles, and suction cups are some of the items commonly used in these experiments. For example, if we take a glass of water, cover it with a piece of cardboard, and invert the glass,…

  12. Experimental Air Pressure Tank Systems for Process Control Education

    ERIC Educational Resources Information Center

    Long, Christopher E.; Holland, Charles E.; Gatzke, Edward P.

    2006-01-01

    In process control education, particularly in the field of chemical engineering, there is an inherent need for industrially relevant hands-on apparatuses that enable one to bridge the gap between the theoretical content of coursework and real-world applications. At the University of South Carolina, two experimental air-pressure tank systems have…

  13. An alternating pressure sequence proposal for an air-cell cushion for preventing pressure ulcers.

    PubMed

    Arias, Sandra; Cardiel, Eladio; Rogeli, Pablo; Mori, Taketoshi; Nakagami, Gojiro; Noguchi, Hiroshi; Sanada, Hiromi

    2014-01-01

    The distribution and release of pressure on ischial regions are two important parameters for evaluating the effectiveness of a cushion; especially the release of pressure over time on ischial tuberosities, which is significant for preventing pressure ulcers. The aim of this work is to evaluate the effect on interface pressure through the application of a proposed alternating pressure sequence for an air-cell cushion. Six healthy volunteers were asked to sit on the air cell cushion, in static and alternating modes, as well as on a typical foam cushion for 12 minutes. Interface pressure was monitored with a matrix sensor system. Interface pressure values on ischial tuberosities, user contact area and pressure distribution were analyzed. Results showed that IP on IT tends to increase in both foam and static cushions, while in alternating cushion IP on IT tends to decrease. User contact area was significantly larger in alternating cushion than in static or foam cushions. Moreover, there is a better pressure re-distribution with alternating cushion than with the other cushions. The goal of the alternating sequence is to redistribute pressure and stimulate the ischial regions in order to promote blood flow and prevent pressure occurring in wheelchair users.

  14. Improved fireman's compressed air breathing system pressure vessel development program

    NASA Technical Reports Server (NTRS)

    King, H. A.; Morris, E. E.

    1973-01-01

    Prototype high pressure glass filament-wound, aluminum-lined pressurant vessels suitable for use in a fireman's compressed air breathing system were designed, fabricated, and acceptance tested in order to demonstrate the feasibility of producing such high performance, lightweight units. The 4000 psi tanks have a 60 standard cubic foot (SCF) air capacity, and have a 6.5 inch diamter, 19 inch length, 415 inch volume, weigh 13 pounds when empty, and contain 33 percent more air than the current 45 SCF (2250 psi) steel units. The current steel 60 SCF (3000 psi) tanks weigh approximately twice as much as the prototype when empty, and are 2 inches, or 10 percent shorter. The prototype units also have non-rusting aluminum interiors, which removes the hazard of corrosion, the need for internal coatings, and the possibility of rust particles clogging the breathing system.

  15. Cold Micro-Plasma Jets in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

    Mohamed, A. H.; Suddala, S.; Schoenbach, K. H.

    2003-10-01

    Direct current microhollow cathode discharges (MHCDs) have been operated in air, nitrogen and oxygen at pressures of one atmosphere. The electrodes are 250 μm thick molybdenum foils, separated by an alumina insulator of the same thickness. A cylindrical hole with a diameter in the 100 μm range is drilled through all layers. By flowing gases at high pressure through this hole, plasma jets with radial dimensions on the same order as the microhole dimensions, and with lengths of up to one centimeter are generated. The gas temperature in these jets was measured by means of a micro-thermocouple. The lowest temperatures of close to room temperature were measured when the flow changed from laminar to turbulent. The results of spectral emission and absorption studies indicate high concentrations of byproducts, such as ozone, when the discharge is operated in air or oxygen. This work is supported by the U.S Air Force Office of Scientific Research (AFOSR).

  16. High pressure differential conductance measurements of (Pb,Sn)Se

    NASA Astrophysics Data System (ADS)

    Paul, Tiffany; Vangennep, Derrick; Jackson, Daniel; Biswas, Amlan; Hamlin, James

    Topological transitions have been recognized as a new type of quantum phase transition. Recently, a number of papers have reported scanning tunneling microscope (STM) measurements of the Landau level spectra of topologically non-trivial materials. Such measurements can offer substantial insight into the nature of the transition between topologically distinct phases. Although applied pressure represents an attractive means to drive a topological quantum phase transition, STM measurements can not be performed under high pressure conditions. In this talk, I will discuss our recent attempts to observe Landau level spectra in compressed (Pb,Sn)Se using differential conductance measurements. Acknowledgements: TAP supported by REU NSF DMR-1461019. Pressure cell development and measurements at high magnetic fields supported by the National High Magnetic Field Laboratory User Collaboration Grants Program. Synthesis, characterization, and high pressure measurements supported by NSF DMR-1453752.

  17. Air and gas pockets in sewerage pressure mains.

    PubMed

    Lubbers, C L; Clemens, F

    2005-01-01

    In The Netherlands, wastewater is collected in municipal areas and transported to large centralised WWTPs by means of an extensive system of pressure mains. Over the past decades these pressure mains did not receive much attention in terms of monitoring of performance or maintenance. For that reason, in practice their state of functioning is often not known. Failure of operation is only noticed when the capacity of the system proves to be insufficient to fulfil the minimum design capacity demand. A recent inventory showed that half of the pressure mains show an increased pressure loss for no directly obvious reason. Many causes may account for the reduction of the system's nominal capacity like an increased wall roughness, scaling or occurrence of free gas in the pipeline. The occurrence of free gas may be caused by degassing of dissolved (bio) gas or by air entrained at the pumps' inlet or at air valves. A research study is started that will focus on three main issues: The description of the gas-water phenomena in wastewater pressure mains with respect to transportation and dynamic hydraulic behaviour, A method to diagnose gas problems, and To overcome future problems by either applying remedial measures or improving the design of wastewater pressure systems. For this study, two experimental facilities are constructed, a small circuit for the study of multi-phase flow and a second, larger one for the research into diagnostic methods. This paper describes the preliminary results of the experiments in the multi-phase circuit.

  18. Evaluation of pressure response in the Los Alamos controlled air incinerator during three incident scenarios

    SciTech Connect

    Vavruska, J.S.; Elsberry, K.; Thompson, T.K.; Pendergrass, J.A.

    1996-05-01

    The Los Alamos Controlled Air Incinerator (CAI) is a system designed to accept radioactive mixed waste containing alpha-emitting radionuclides. A mathematical model was developed to predict the pressure response throughout the offgas treatment system of the CAI during three hypothetical incident scenarios. The scenarios examined included: (1) loss of burner flame and failure of the flame safeguard system with subsequent reignition of fuel gas in the primary chamber, (2) pyrolytic gas buildup from a waste package due to loss of induced draft and subsequent restoration of induced draft, and (3) accidental charging of propellant spray cans in a solid waste package to the primary chamber during a normal feed cycle. For each of the three scenarios, the finite element computer model was able to determine the transient pressure surge and decay response throughout the system. Of particular interest were the maximum absolute pressures attainable at critical points in the system as well as maximum differential pressures across the high efficiency particulate air (HEPA) filters. Modeling results indicated that all three of the scenarios resulted in maximum HEPA filter differential pressures well below the maximum allowable levels.

  19. The hybrid pressurized air receiver (HPAR) in the SUNDISC cycle

    NASA Astrophysics Data System (ADS)

    Heller, Lukas; Hoffmann, Jaap; Gauché, Paul

    2016-05-01

    Tubular metallic pressurized air solar receivers face challenges in terms of temperature distribution on the absorber tubes and the limited sustainable solar influx. The HPAR concept aims at mitigating these problems through a macro-volumetric design and a secondary non-pressurized air flow around the absorber elements. Here, a 360◦ manifestation of this concept for implementation in the dual-pressure SUNDISC cycle is presented. Computationally inexpensive models for the numerous heat flows were developed for use in parametric studies of a receiver's geometric layout. Initial findings are presented on the optical penetration of concentrated solar radiation into the absorber structure, blocking of thermal radiation from hot surfaces and the influence of the flow path through the heated tubes. In the basic design the heat transfer to the non-pressurized air stream is found to be insufficient and possible measures for its improvement are given. Their effect will be examined in more detailed models of external convection and thermal radiation to be able to provide performance estimates of the system.

  20. One-Component Pressure-Temperature Phase Diagrams in the Presence of Air

    ERIC Educational Resources Information Center

    Andrade-Gamboa, Julio; Martire, Daniel O.; Donati, Edgardo R.

    2010-01-01

    One-component phase diagrams are good approximations to predict pressure-temperature ("P-T") behavior of a substance in the presence of air, provided air pressure is not much higher than the vapor pressure. However, at any air pressure, and from the conceptual point of view, the use of a traditional "P-T" phase diagram is not strictly correct. In…

  1. Generation of subnanosecond electron beams in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kostyrya, I. D.; Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Rybka, D. V.

    2009-11-01

    Optimum conditions for the generation of runaway electron beams with maximum current amplitudes and densities in nanosecond pulsed discharges in air at atmospheric pressure are determined. A supershort avalanche electron beam (SAEB) with a current amplitude of ˜30 A, a current density of ˜20 A/cm2, and a pulse full width at half maximum (FWHM) of ˜100 ps has been observed behind the output foil of an air-filled diode. It is shown that the position of the SAEB current maximum relative to the voltage pulse front exhibits a time shift that varies when the small-size collector is moved over the foil surface.

  2. Cuffless differential blood pressure estimation using smart phones.

    PubMed

    Chandrasekaran, Vikram; Dantu, Ram; Jonnada, Srikanth; Thiyagaraja, Shanti; Subbu, Kalyan Pathapati

    2013-04-01

    Smart phones today have become increasingly popular with the general public for their diverse functionalities such as navigation, social networking, and multimedia facilities. These phones are equipped with high-end processors, high-resolution cameras, and built-in sensors such as accelerometer, orientation-sensor, and light-sensor. According to comScore survey, 26.2% of U.S. adults use smart phones in their daily lives. Motivated by this statistic and the diverse capability of smart phones, we focus on utilizing them for biomedical applications. We present a new application of the smart phone with its built-in camera and microphone replacing the traditional stethoscope and cuff-based measurement technique, to quantify vital signs such as heart rate and blood pressure. We propose two differential blood pressure estimating techniques using the heartbeat and pulse data. The first method uses two smart phones whereas the second method replaces one of the phones with a customized external microphone. We estimate the systolic and diastolic pressure in the two techniques by computing the pulse pressure and the stroke volume from the data recorded. By comparing the estimated blood pressure values with those measured using a commercial blood pressure meter, we obtained encouraging results of 95-100% accuracy.

  3. Temperature and pressure influence on maximum rates of pressure rise during explosions of propane-air mixtures in a spherical vessel.

    PubMed

    Razus, D; Brinzea, V; Mitu, M; Movileanu, C; Oancea, D

    2011-06-15

    The maximum rates of pressure rise during closed vessel explosions of propane-air mixtures are reported, for systems with various initial concentrations, pressures and temperatures ([C(3)H(8)]=2.50-6.20 vol.%, p(0)=0.3-1.3 bar; T(0)=298-423 K). Experiments were performed in a spherical vessel (Φ=10 cm) with central ignition. The deflagration (severity) index K(G), calculated from experimental values of maximum rates of pressure rise is examined against the adiabatic deflagration index, K(G, ad), computed from normal burning velocities and peak explosion pressures. At constant temperature and fuel/oxygen ratio, both the maximum rates of pressure rise and the deflagration indices are linear functions of total initial pressure, as reported for other fuel-air mixtures. At constant initial pressure and composition, the maximum rates of pressure rise and deflagration indices are slightly influenced by the initial temperature; some influence of the initial temperature on maximum rates of pressure rise is observed only for propane-air mixtures far from stoichiometric composition. The differentiated temperature influence on the normal burning velocities and the peak explosion pressures might explain this behaviour. PMID:21514044

  4. Temperature and pressure influence on maximum rates of pressure rise during explosions of propane-air mixtures in a spherical vessel.

    PubMed

    Razus, D; Brinzea, V; Mitu, M; Movileanu, C; Oancea, D

    2011-06-15

    The maximum rates of pressure rise during closed vessel explosions of propane-air mixtures are reported, for systems with various initial concentrations, pressures and temperatures ([C(3)H(8)]=2.50-6.20 vol.%, p(0)=0.3-1.3 bar; T(0)=298-423 K). Experiments were performed in a spherical vessel (Φ=10 cm) with central ignition. The deflagration (severity) index K(G), calculated from experimental values of maximum rates of pressure rise is examined against the adiabatic deflagration index, K(G, ad), computed from normal burning velocities and peak explosion pressures. At constant temperature and fuel/oxygen ratio, both the maximum rates of pressure rise and the deflagration indices are linear functions of total initial pressure, as reported for other fuel-air mixtures. At constant initial pressure and composition, the maximum rates of pressure rise and deflagration indices are slightly influenced by the initial temperature; some influence of the initial temperature on maximum rates of pressure rise is observed only for propane-air mixtures far from stoichiometric composition. The differentiated temperature influence on the normal burning velocities and the peak explosion pressures might explain this behaviour.

  5. The Jar Magic -- Instructional Activities for Teaching Air Pressure

    NASA Astrophysics Data System (ADS)

    Ku, Bing-Hong; Chen, Chyong-Sun

    2013-12-01

    There are a variety of impressive activities designed for teaching the concept of air pressure to junior high school students. Water, glasses, balloons, plastic bottles, and suction cups are some of the items commonly used in these experiments. For example, if we take a glass of water, cover it with a piece of cardboard, and invert the glass, amazingly, no water spills out. Further, one may also use balloons and plastic bottles as the components in another experiment. Place a balloon in a plastic bottle and spread the balloon's mouth over the bottle's rim. Inflate the balloon by blowing into it. Students will be astonished at the fact that the balloon remains inflated even though its mouth is open. Making suction cups "stick" to the wall is also an instance of proving how air pressure works.

  6. Microcontrolled air-mattress for ulcer by pressure prevention

    NASA Astrophysics Data System (ADS)

    Pasluosta, Cristian F.; Fontana, Juan M.; Beltramone, Diego A.; Taborda, Ricardo A. M.

    2007-11-01

    An ulcer by pressure is produced when a constant pressure is exerted over the skin. This generates the collapse of the blood vessels and, therefore, a lack in the contribution of the necessary nutrients for the affected zone. As a consequence, the skin deteriorates, eventually causing an ulcer. In order to prevent it, a protocol must be applied to the patient, which is reflected on time and cost of treatment. There are some air mattresses available for this purpose, but whose performance does not fulfill all requirements. The prototype designed in our laboratory is based on the principle of the air mattress. Its objective is to improve on existing technologies and, due to an increased automation, reduce time dedication for personnel in charge of the patient. A clinical experience was made in the local Emergencies Hospital and also in an institution dedicated to aged patients care. In both cases, the results obtained and the comments from the personnel involved were favorable.

  7. AIR SEPARATION BY PRESSURE SWING ADSORPTION USING SUPERIOR ADSORBENTS

    SciTech Connect

    Ralph T. Yang

    2001-08-31

    Li-X zeolite (Si/Al = 1.0) is currently the best sorbent for use in the separation of air by adsorption processes. In particular, pressure swing adsorption (PSA) using zeolite sorbents is being increasingly used for air separation. Silver is also known to strongly affect the adsorptive properties of zeolites; and it is known that thermal vacuum dehydration of silver zeolites leads to the formation of silver clusters within the zeolite. In this work we have synthesized type X zeolites containing Ag and also varying mixtures of Li and Ag. In this project, we developed the Ag-containing zeolite as the best sorbent for air separation. We have also studied Co-ligand compounds as oxygen-selective sorbents. Syntheses, structural characterization and adsorption properties have been performed on all sorbents. The results are described in detail in 5 chapters.

  8. Benzene Dissociation in DC Atmospheric Pressure Air Glow Discharges

    NASA Astrophysics Data System (ADS)

    Jiang, Chunqi; Stark, Robert H.; Schoenbach, Karl H.

    2001-10-01

    By using a micro-hollow cathode discharge (MHCD) as an electron source to lower or eliminate the cathode fall voltage, a glow discharge could be operated in a dc atmospheric pressure air [1]. The effect of this glow discharge plasma on VOC (Volatile Organic Compound) remediation, particularly, benzene remediation, has been studied. A higher than 90 % destruction rate has been obtained by flowing a 300 ppm benzene/ dry air mixture through the plasma filament. The plasma is confined by a dielectric to a cross-section of 1 mm by 1.5 mm and extends over a depth of 0.8 mm. With a flow rate of 100 sccm, the residence time of the gas in the plasma column is 0.7 ms. A destruction efficiency of more than 0.5 L/kJ has been measured. The energy efficiency is 0.9 g/kWh which is comparable to that achieved by low pressure glow discharges in benzene/ noble gas mixtures [2]. References: [1] R. H. Stark and K. H. Schoenbach, "Direct Current Glow Discharges in Atmospheric Air," Appl. Phys. Lett. 89, 3568 (2001). [2] D. L. McCorkle, W. Ding, C. Ma and L. A. Pinnaduwage, "Dissociation of Benzene and Methylene Chloride Based on Enhanced Dissociative Electron Attachment to Highly Excited Molecules," J. Phys. D: Appl. Phys. 32, 46 (1999). Acknowledgments: This work is supported by the Air Force Office of Scientific Research.

  9. Low pressure high speed Stirling air engine. Final technical report

    SciTech Connect

    Ross, M.A.

    1980-06-16

    The purpose of this project was to design, construct and test a simple, appropriate technology low pressure, high speed, wood-fired Stirling air engine of 100 W output. The final design was a concentric piston/displacer engine of 454 in. bore and 1 in. stroke with a rhombic drive mechanism. The project engine was ultimately completed and tested, using a propane burner for all tests as a matter of convenience. The 100 W aim was exceeded, at atmospheric pressure, over a wide range of engine speed with the maximum power being 112 W at 1150 rpm. A pressure can was constructed to permit pressurization; however the grant funds were running out, and the only pressurized power test attempted was unsuccessful due to seal difficulties. This was a disappointment because numerous tests on the 4 cubic inch engine suggested power would be more than doubled with pressurization at 25 psig. A manifold was designed and constructed to permit operation of the engine over a standard No. 40 pot bellied stove. The engine was run successfully, but at reduced speed and power, over this stove. The project engine started out being rather noisy in operation, but modifications ultimately resulted in a very quiet engine. Various other difficulties and their solutions also are discussed. (LCL)

  10. Brass plasmoid in external magnetic field at different air pressures

    SciTech Connect

    Patel, D. N.; Thareja, Raj K.; Pandey, Pramod K.

    2013-10-15

    The behavior of expanding brass plasmoid generated by 266 nm wavelength of Nd:YAG laser in nonuniform magnetic field at different air pressures has been examined using optical emission spectroscopy and fast imaging of plasma plumes. The splitting of the plasma plumes and enhancement of intensity of Cu I at 510.5 nm in the presence of magnetic field at lower pressures are discussed. The threading and expulsion of the magnetic field lines through the plasmoid are correlated with the ambient pressure. The stoichiometry of the plasma plume is not significantly influenced by the magnetic field; however, the abundance of neutral to ionic species of Cu and Zn is greatly influenced by the magnetic field.

  11. A stagnation pressure probe for droplet-laden air flow

    NASA Technical Reports Server (NTRS)

    Murthy, S. N. B.; Leonardo, M.; Ehresman, C. M.

    1985-01-01

    It is often of interest in a droplet-laden gas flow to obtain the stagnation pressure of both the gas phase and the mixture. A flow-decelerating probe (TPF), with separate, purged ports for the gas phase and the mixture and with a bleed for accumulating liquid at the closed end, has been developed. Measurements obtained utilizing the TPF in a nearly isothermal air-water droplet mixture flow in a smooth circular pipe under various conditions of flow velocity, pressure, liquid concentration and droplet size are presented and compared with data obtained under identical conditions with a conventional, gas phase stagnation pressure probe (CSP). The data obtained with the CSP and TPF probes are analyzed to determine the applicability of the two probes in relation to the multi-phase characteristics of the flow and the geometry of the probe.

  12. The influence of intraocular pressure and air jet pressure on corneal contactless tonometry tests.

    PubMed

    Simonini, Irene; Pandolfi, Anna

    2016-05-01

    The air puff is a dynamic contactless tonometer test used in ophthalmology clinical practice to assess the biomechanical properties of the human cornea and the intraocular pressure due to the filling fluids of the eye. The test is controversial, since the dynamic response of the cornea is governed by the interaction of several factors which cannot be discerned within a single measurement. In this study we describe a numerical model of the air puff tests, and perform a parametric analysis on the major action parameters (jet pressure and intraocular pressure) to assess their relevance on the mechanical response of a patient-specific cornea. The particular cornea considered here has been treated with laser reprofiling to correct myopia, and the parametric study has been conducted on both the preoperative and postoperative geometries. The material properties of the cornea have been obtained by means of an identification procedure that compares the static biomechanical response of preoperative and postoperative corneas under the physiological IOP. The parametric study on the intraocular pressure suggests that the displacement of the cornea׳s apex can be a reliable indicator for tonometry, and the one on the air jet pressure predicts the outcomes of two or more distinct measurements on the same cornea, which can be used in inverse procedures to estimate the material properties of the tissue.

  13. Breakdown of air pockets in downwardly inclined sewerage pressure mains.

    PubMed

    Lubbers, C L; Clemens, F H L R

    2006-01-01

    In the Netherlands, wastewater is collected in municipal areas and transported to centralised WWTPs by an extensive system of pressure mains. Over the last decades these pressure mains did not receive much attention in terms of monitoring of performance or maintenance. A recent inventory showed that half of the pressure mains show an increased pressure loss for no directly obvious reason. One of the many causes that account for the reduction of the flow capacity is the occurrence of free gas in the pipeline. During dry weather periods with low flow velocities, gas may accumulate at high points in the system. Once the velocity increases during storm weather flow, the air pockets may be broken down and transported to the end of the system. A research study is started focussing on the description of the gas-water phenomena in wastewater pressure mains with respect to transportation of gas. An experimental facility is constructed for the study of multi-phase flow. This paper describes the preliminary results of experiments on breakdown rates of gas pockets as a function of inclination angle and water flow rate. The results show an increasing breakdown rate with increasing inclination angle.

  14. Air Flow and Pressure Drop Measurements Across Porous Oxides

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus air flow is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected flow decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of air flow versus processing parameters and the resulting porosity size and distribution.

  15. Comparison of deliverable and exhaustible pressurized air flow rates in laboratory gloveboxes

    SciTech Connect

    Compton, J.A.

    1994-10-01

    Calculations were performed to estimate the maximum credible flow rates of pressurized air into Plutonium Process Support Laboratories gloveboxes. Classical equations for compressible fluids were used to estimate the flow rates. The calculated maxima were compared to another`s estimates of glovebox exhaust flow rates and corresponding glovebox internal pressures. No credible pressurized air flow rate will pressurize a glovebox beyond normal operating limits. Unrestricted use of the pressurized air supply is recommended.

  16. Microwave generation of stable atmospheric-pressure fireballs in air.

    PubMed

    Stephan, Karl D

    2006-11-01

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed. PMID:17279961

  17. Cold atmospheric pressure air plasma jet for medical applications

    SciTech Connect

    Kolb, J. F.; Price, R. O.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H.; Mohamed, A.-A H.; Swanson, R. J.

    2008-06-16

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2 cm long plasma jet. With increasing flow rate, the flow becomes turbulent and temperatures of the jet are reduced to values close to room temperature. Utilizing the jet, yeast grown on agar can be eradicated with a treatment of only a few seconds. Conversely, animal studies show no skin damage even with exposures ten times longer than needed for pathogen extermination. This cold plasma jet provides an effective mode of treatment for yeast infections of the skin.

  18. Cold atmospheric pressure air plasma jet for medical applications

    NASA Astrophysics Data System (ADS)

    Kolb, J. F.; Mohamed, A.-A. H.; Price, R. O.; Swanson, R. J.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H.

    2008-06-01

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2cm long plasma jet. With increasing flow rate, the flow becomes turbulent and temperatures of the jet are reduced to values close to room temperature. Utilizing the jet, yeast grown on agar can be eradicated with a treatment of only a few seconds. Conversely, animal studies show no skin damage even with exposures ten times longer than needed for pathogen extermination. This cold plasma jet provides an effective mode of treatment for yeast infections of the skin.

  19. Vandenberg Air Force Base Pressure Gradient Wind Study

    NASA Technical Reports Server (NTRS)

    Shafer, Jaclyn A.

    2013-01-01

    Warning category winds can adversely impact day-to-day space lift operations at Vandenberg Air Force Base (VAFB) in California. NASA's Launch Services Program and other programs at VAFB use wind forecasts issued by the 30 Operational Support Squadron Weather Flight (30 OSSWF) to determine if they need to limit activities or protect property such as a launch vehicle. The 30 OSSWF tasked the AMU to develop an automated Excel graphical user interface that includes pressure gradient thresholds between specific observing stations under different synoptic regimes to aid forecasters when issuing wind warnings. This required the AMU to determine if relationships between the variables existed.

  20. Microwave generation of stable atmospheric-pressure fireballs in air

    SciTech Connect

    Stephan, Karl D.

    2006-11-15

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  1. Microwave generation of stable atmospheric-pressure fireballs in air.

    PubMed

    Stephan, Karl D

    2006-11-01

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  2. Microwave generation of stable atmospheric-pressure fireballs in air

    NASA Astrophysics Data System (ADS)

    Stephan, Karl D.

    2006-11-01

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  3. Pressure measurements of a three wave journal air bearing

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Addy, Harold E., Jr.

    1994-01-01

    In order to validate theoretical predictions of a wave journal bearing concept, a bench test rig was assembled at NASA Lewis Research Center to measure the steady-state performance of a journal air bearing. The tester can run up to 30,000 RPM and the spindle has a run out of less than 1 micron. A three wave journal bearing (50 mm diameter and 58 mm length) has been machined at NASA Lewis. The pressures at 16 ports along the bearing circumference at the middle of the bearing length were measured and compared to the theoretical prediction. The bearing ran at speeds up to 15,000 RPM and certain loads. Good agreement was found between the measured and calculated pressures.

  4. Differential Pressures on a Pitot-venturi and a Pitot-static Nozzle over 360 Degrees Pitch and Yaw

    NASA Technical Reports Server (NTRS)

    Bear, R M

    1928-01-01

    Measurements of the differential pressures on two navy air-speed nozzles, consisting of a Zahm type Pitot-Venturi tube and a SQ-16 two-pronged Pitot-static tube, in a tunnel air stream of fixed speed at various angles of pitch and yaw between 0 degrees and plus or minus 180 degrees. This shows for a range over -20 degrees to +20 degrees pitch and yaw, indicated air speeds varying very slightly over 2 per cent for the Zahm type and a maximum of about 5 per cent for the SQ-16 type from the calibrated speed at 0 degree. For both types of air-speed nozzle the indicated air speed increases slightly as the tubes are pitched or yawed several degrees from their normal 0 degrees altitude, attains a maximum around plus or minus 15 degrees to 25 degrees, declines rapidly therefrom as plus or minus 40 degrees is passed, to zero in the vicinity of plus or minus 70 degrees to 100 degrees, and thence fluctuates irregular from thereabouts to plus or minus 180 degrees. The complete variation in indicated air speed for the two tubes over 360 degree pitch and yaw is graphically portrayed in figures 9 and 10. For the same air speed and 0 degree pitch and yaw the differential pressure of the Zahm type Pitot-Venturi nozzle is about seven times that of the SQ-16 type two-prolonged Pitot-static nozzle.

  5. Heart-rate monitoring by air pressure and causal analysis

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Naoki; Nakajima, Hiroshi; Hata, Yutaka

    2011-06-01

    Among lots of vital signals, heart-rate (HR) is an important index for diagnose human's health condition. For instance, HR provides an early stage of cardiac disease, autonomic nerve behavior, and so forth. However, currently, HR is measured only in medical checkups and clinical diagnosis during the rested state by using electrocardiograph (ECG). Thus, some serious cardiac events in daily life could be lost. Therefore, a continuous HR monitoring during 24 hours is desired. Considering the use in daily life, the monitoring should be noninvasive and low intrusive. Thus, in this paper, an HR monitoring in sleep by using air pressure sensors is proposed. The HR monitoring is realized by employing the causal analysis among air pressure and HR. The causality is described by employing fuzzy logic. According to the experiment on 7 males at age 22-25 (23 on average), the correlation coefficient against ECG is 0.73-0.97 (0.85 on average). In addition, the cause-effect structure for HR monitoring is arranged by employing causal decomposition, and the arranged causality is applied to HR monitoring in a setting posture. According to the additional experiment on 6 males, the correlation coefficient is 0.66-0.86 (0.76 on average). Therefore, the proposed method is suggested to have enough accuracy and robustness for some daily use cases.

  6. Prenatal Air Pollution Exposure and Newborn Blood Pressure

    PubMed Central

    Rifas-Shiman, Sheryl L.; Melly, Steven J.; Kloog, Itai; Luttmann-Gibson, Heike; Zanobetti, Antonella; Coull, Brent A.; Schwartz, Joel D.; Mittleman, Murray A.; Oken, Emily; Gillman, Matthew W.; Koutrakis, Petros; Gold, Diane R.

    2015-01-01

    Background Air pollution exposure has been associated with increased blood pressure in adults. Objective: We examined associations of antenatal exposure to ambient air pollution with newborn systolic blood pressure (SBP). Methods: We studied 1,131 mother–infant pairs in a Boston, Massachusetts, area pre-birth cohort. We calculated average exposures by trimester and during the 2 to 90 days before birth for temporally resolved fine particulate matter (≤ 2.5 μm; PM2.5), black carbon (BC), nitrogen oxides, nitrogen dioxide, ozone (O3), and carbon monoxide measured at stationary monitoring sites, and for spatiotemporally resolved estimates of PM2.5 and BC at the residence level. We measured SBP at a mean age of 30 ± 18 hr with an automated device. We used mixed-effects models to examine associations between air pollutant exposures and SBP, taking into account measurement circumstances; child’s birth weight; mother’s age, race/ethnicity, socioeconomic position, and third-trimester BP; and time trend. Estimates represent differences in SBP associated with an interquartile range (IQR) increase in each pollutant. Results: Higher mean PM2.5 and BC exposures during the third trimester were associated with higher SBP (e.g., 1.0 mmHg; 95% CI: 0.1, 1.8 for a 0.32-μg/m3 increase in mean 90-day residential BC). In contrast, O3 was negatively associated with SBP (e.g., –2.3 mmHg; 95% CI: –4.4, –0.2 for a 13.5-ppb increase during the 90 days before birth). Conclusions: Exposures to PM2.5 and BC in late pregnancy were positively associated with newborn SBP, whereas O3 was negatively associated with SBP. Longitudinal follow-up will enable us to assess the implications of these findings for health during later childhood and adulthood. Citation: van Rossem L, Rifas-Shiman SL, Melly SJ, Kloog I, Luttmann-Gibson H, Zanobetti A, Coull BA, Schwartz JD, Mittleman MA, Oken E, Gillman MW, Koutrakis P, Gold DR. 2015. Prenatal air pollution exposure and newborn blood pressure

  7. Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

    NASA Technical Reports Server (NTRS)

    Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

  8. Air Pressure Responses to Sudden Vocal Tract Pressure Bleeds During Production of Stop Consonants: New Evidence of Aeromechanical Regulation

    PubMed Central

    Zajac, David J.; Weissler, Mark C.

    2011-01-01

    Two studies were conducted to evaluate short-latency vocal tract air pressure responses to sudden pressure bleeds during production of voiceless bilabial stop consonants. It was hypothesized that the occurrence of respiratory reflexes would be indicated by distinct patterns of responses as a function of bleed magnitude. In Study 1, 19 adults produced syllable trains of /pΛ/ using a mouthpiece coupled to a computer-controlled perturbator. The device randomly created bleed apertures that ranged from 0 to 40 mm2 during production of the 2nd or 4th syllable of an utterance. Although peak oral air pressure dropped in a linear manner across bleed apertures, it averaged 2 to 3 cm H2O at the largest bleed. While slope of oral pressure also decreased in a linear trend, duration of the oral pressure pulse remained relatively constant. The patterns suggest that respiratory reflexes, if present, have little effect on oral air pressure levels. In Study 2, both oral and subglottal air pressure responses were monitored in 2 adults while bleed apertures of 20 and 40 mm2 were randomly created. For 1 participant, peak oral air pressure dropped across bleed apertures, as in Study 1. Subglottal air pressure and slope, however, remained relatively stable. These patterns provide some support for the occurrence of respiratory reflexes to regulate subglottal air pressure. Overall, the studies indicate that the inherent physiologic processes of the respiratory system, which may involve reflexes, and passive aeromechanical resistance of the upper airway are capable of developing oral air pressure in the face of substantial pressure bleeds. Implications for understanding speech production and the characteristics of individuals with velopharyngeal dysfunction are discussed. PMID:15324286

  9. Air pressure responses to sudden vocal tract pressure bleeds during production of stop consonants: new evidence of aeromechanical regulation.

    PubMed

    Zajac, David J; Weissler, Mark C

    2004-08-01

    Two studies were conducted to evaluate short-latency vocal tract air pressure responses to sudden pressure bleeds during production of voiceless bilabial stop consonants. It was hypothesized that the occurrence of respiratory reflexes would be indicated by distinct patterns of responses as a function of bleed magnitude. In Study 1, 19 adults produced syllable trains of "puh" using a mouthpiece coupled to a computer-controlled perturbator. The device randomly created bleed apertures that ranged from 0 to 40 mm2 during production of the 2nd or 4th syllable of an utterance. Although peak oral air pressure dropped in a linear manner across bleed apertures, it averaged 2 to 3 cm H2O at the largest bleed. While slope of oral pressure also decreased in a linear trend, duration of the oral pressure pulse remained relatively constant. The patterns suggest that respiratory reflexes, if present, have little effect on oral air pressure levels. In Study 2, both oral and subglottal air pressure responses were monitored in 2 adults while bleed apertures of 20 and 40 mm2 were randomly created. For 1 participant, peak oral air pressure dropped across bleed apertures, as in Study 1. Subglottal air pressure and slope, however, remained relatively stable. These patterns provide some support for the occurrence of respiratory reflexes to regulate subglottal air pressure. Overall, the studies indicate that the inherent physiologic processes of the respiratory system, which may involve reflexes, and passive aeromechanical resistance of the upper airway are capable of developing oral air pressure in the face of substantial pressure bleeds. Implications for understanding speech production and the characteristics of individuals with velopharyngeal dysfunction are discussed.

  10. Converging swirling liquid jets from pressure swirl atomizers: Effect of inner air pressure

    NASA Astrophysics Data System (ADS)

    Sivakumar, D.; Raghunandan, B. N.

    2002-12-01

    Converging swirling liquid jets from pressure swirl atomizers injected into atmospheric air are studied experimentally using still and cine photographic techniques in the context of liquid-liquid coaxial swirl atomizers used in liquid rocket engines. The jet exhibits several interesting flow features in contrast to the nonswirling liquid jets (annular liquid jets) studied in the literature. The swirl motion creates multiple converging sections in the jet, which gradually collapse one after the other due to the liquid sheet breakup with increasing Weber number (We). This is clearly related to the air inside the converging jet which exhibits a peculiar variation of the pressure difference across the liquid sheet, ΔP, with We. The variation shows a decreasing trend of ΔP with We in an overall sense, but exhibits local maxima and minima at specific flow conditions. The number of maxima or minima observed in the curve depends on the number of converging sections seen in the jet at the lowest We. An interesting feature of this variation is that it delineates the regions of prominent jet flow features like the oscillating jet region, nonoscillating jet region, number of converging sections, and so on. Numerical predictions of the jet characteristics are obtained by modifying an existing nonswirling liquid jet model by including the swirling motion. The comparison between the experimental and numerical measurements shows that the pressure difference across the liquid sheet is important for the jet behavior and cannot be neglected in any theoretical analysis.

  11. 30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND...

  12. 30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND...

  13. 30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND...

  14. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND...

  15. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Portable air receivers and other unfired pressure vessels... SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other Than Ship's Equipment § 1915.172 Portable air receivers and other unfired pressure vessels. (a) Portable, unfired...

  16. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Portable air receivers and other unfired pressure vessels... SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other Than Ship's Equipment § 1915.172 Portable air receivers and other unfired pressure vessels. (a) Portable, unfired...

  17. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Portable air receivers and other unfired pressure vessels... SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other Than Ship's Equipment § 1915.172 Portable air receivers and other unfired pressure vessels. (a) Portable, unfired...

  18. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Portable air receivers and other unfired pressure vessels... SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other Than Ship's Equipment § 1915.172 Portable air receivers and other unfired pressure vessels. (a) Portable, unfired...

  19. 30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND...

  20. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Portable air receivers and other unfired pressure vessels... SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other Than Ship's Equipment § 1915.172 Portable air receivers and other unfired pressure vessels. (a) Portable, unfired...

  1. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND...

  2. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND...

  3. 30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND...

  4. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND...

  5. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND...

  6. A wet/wet differential pressure sensor for measuring vertical hydraulic gradient

    SciTech Connect

    Fritz, Brad G.; Mackley, Rob D.

    2008-12-13

    This article describes a new tool for measuring vertical hydraulic gradient in the hyporheic zone. It is essentially an electronic version of an established differential pressure measurement technique.

  7. High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

    PubMed

    Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2015-09-18

    High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%.

  8. High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

    PubMed

    Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2015-09-18

    High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%. PMID:26087881

  9. Study of short atmospheric pressure dc glow microdischarge in air

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

    2011-10-01

    The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen

  10. [Aerodynamics study on pressure changes inside pressure-type whole-body plethysmograph produced by flowing air].

    PubMed

    Xu, Wei-Hua; Shen, Hua-Hao

    2010-02-25

    When using pressure-type plethysmography to test lung function of rodents, calculation of lung volume is always based on Boyle's law. The precondition of Boyle's law is that perfect air is static. However, air in the chamber is flowing continuously when a rodent breathes inside the chamber. Therefore, Boyle's law, a principle of air statics, may not be appropriate for measuring pressure changes of flowing air. In this study, we deduced equations for pressure changes inside pressure-type plethysmograph and then designed three experiments to testify the theoretic deduction. The results of theoretic deduction indicated that increased pressure was generated from two sources: one was based on Boyle's law, and the other was based on the law of conservation of momentum. In the first experiment, after injecting 0.1 mL, 0.2 mL, 0.4 mL of air into the plethysmograph, the pressure inside the chamber increased sharply to a peak value, then promptly decreased to horizontal pressure. Peak values were significantly higher than the horizontal values (P<0.001). This observation revealed that flowing air made an extra effect on air pressure in the plethysmograph. In the second experiment, the same volume of air was injected into the plethysmograph at different frequencies (0, 0.5, 1, 2, 3 Hz) and pressure changes inside were measured. The results showed that, with increasing frequencies, the pressure changes in the chamber became significantly higher (P<0.001). In the third experiment, small animal ventilator and pipette were used to make two types of airflow with different functions of time. The pressure changes produced by the ventilator were significantly greater than those produced by the pipette (P<0.001). Based on the data obtained, we draw the conclusion that, the flow of air plays a role in pressure changes inside the plethysmograph, and the faster the airflow is, the higher the pressure changes reach. Furthermore, the type of airflow also influences the pressure changes

  11. [Aerodynamics study on pressure changes inside pressure-type whole-body plethysmograph produced by flowing air].

    PubMed

    Xu, Wei-Hua; Shen, Hua-Hao

    2010-02-25

    When using pressure-type plethysmography to test lung function of rodents, calculation of lung volume is always based on Boyle's law. The precondition of Boyle's law is that perfect air is static. However, air in the chamber is flowing continuously when a rodent breathes inside the chamber. Therefore, Boyle's law, a principle of air statics, may not be appropriate for measuring pressure changes of flowing air. In this study, we deduced equations for pressure changes inside pressure-type plethysmograph and then designed three experiments to testify the theoretic deduction. The results of theoretic deduction indicated that increased pressure was generated from two sources: one was based on Boyle's law, and the other was based on the law of conservation of momentum. In the first experiment, after injecting 0.1 mL, 0.2 mL, 0.4 mL of air into the plethysmograph, the pressure inside the chamber increased sharply to a peak value, then promptly decreased to horizontal pressure. Peak values were significantly higher than the horizontal values (P<0.001). This observation revealed that flowing air made an extra effect on air pressure in the plethysmograph. In the second experiment, the same volume of air was injected into the plethysmograph at different frequencies (0, 0.5, 1, 2, 3 Hz) and pressure changes inside were measured. The results showed that, with increasing frequencies, the pressure changes in the chamber became significantly higher (P<0.001). In the third experiment, small animal ventilator and pipette were used to make two types of airflow with different functions of time. The pressure changes produced by the ventilator were significantly greater than those produced by the pipette (P<0.001). Based on the data obtained, we draw the conclusion that, the flow of air plays a role in pressure changes inside the plethysmograph, and the faster the airflow is, the higher the pressure changes reach. Furthermore, the type of airflow also influences the pressure changes.

  12. Magnetic resonance velocity imaging derived pressure differential using control volume analysis

    PubMed Central

    2011-01-01

    Background Diagnosis and treatment of hydrocephalus is hindered by a lack of systemic understanding of the interrelationships between pressures and flow of cerebrospinal fluid in the brain. Control volume analysis provides a fluid physics approach to quantify and relate pressure and flow information. The objective of this study was to use control volume analysis and magnetic resonance velocity imaging to non-invasively estimate pressure differentials in vitro. Method A flow phantom was constructed and water was the experimental fluid. The phantom was connected to a high-resolution differential pressure sensor and a computer controlled pump producing sinusoidal flow. Magnetic resonance velocity measurements were taken and subsequently analyzed to derive pressure differential waveforms using momentum conservation principles. Independent sensor measurements were obtained for comparison. Results Using magnetic resonance data the momentum balance in the phantom was computed. The measured differential pressure force had amplitude of 14.4 dynes (pressure gradient amplitude 0.30 Pa/cm). A 12.5% normalized root mean square deviation between derived and directly measured pressure differential was obtained. These experiments demonstrate one example of the potential utility of control volume analysis and the concepts involved in its application. Conclusions This study validates a non-invasive measurement technique for relating velocity measurements to pressure differential. These methods may be applied to clinical measurements to estimate pressure differentials in vivo which could not be obtained with current clinical sensors. PMID:21414222

  13. Response of entrained air-void systems in cement paste to pressure

    NASA Astrophysics Data System (ADS)

    Frazier, Robert

    2011-12-01

    Scope and Method of Study: Determine the response of entrained air-void systems in fresh cement paste to applied pressures by utilizing micro-computed tomography. Compare results to those suggested by the ASTM C231 Type B pressure meter calibration equations. Findings and Conclusions: The results of this research suggest that although the Type B pressure meter assumptions are valid for the compression of individual voids, the volume of air-voids which dissolve under pressure is significant enough to register noticeable errors when using a synthetic air-entraining admixture with the Type B pressure meter test. Results currently suggest that air-void systems with a significant percentage of small voids present will have higher deviation from the Boyle's Law model used by the Type B pressure meter due to the dissolution of these air-voids.

  14. Compression-ignition Engine Performance at Altitudes and at Various Air Pressures and Temperatures

    NASA Technical Reports Server (NTRS)

    Moore, Charles S; Collins, John H

    1937-01-01

    Engine test results are presented for simulated altitude conditions. A displaced-piston combustion chamber on a 5- by 7-inch single cylinder compression-ignition engine operating at 2,000 r.p.m. was used. Inlet air temperature equivalent to standard altitudes up to 14,000 feet were obtained. Comparison between performance at altitude of the unsupercharged compression-ignition engine compared favorably with the carburetor engine. Analysis of the results for which the inlet air temperature, inlet air pressure, and inlet and exhaust pressure were varied indicates that engine performance cannot be reliably corrected on the basis of inlet air density or weight of air charge. Engine power increases with inlet air pressure and decreases with inlet air temperatures very nearly as straight line relations over a wide range of air-fuel ratios. Correction factors are given.

  15. Fast step-response settling of micro electrostatic actuators operated at low air pressure using input shaping

    NASA Astrophysics Data System (ADS)

    Mol, L.; Rocha, L. A.; Cretu, E.; Wolffenbuttel, R. F.

    2009-07-01

    Squeeze-film damping is highly inadequate in low-pressure systems or in systems where air pressure and/or gap dimensions are poorly defined. Input shaping has been used to circumvent the oscillations typically associated with under-damped mass-spring-damper systems and drastically decrease the settling time. The proposed method does not rely on feedback but solely on the system dynamics. The required input signal is derived analytically from the differential equation describing the system. The resulting device response is simulated and experimentally verified on an electrostatically actuated microstructure. Settling occurs even faster than for an equivalent critically damped system.

  16. Windowless transition between atmospheric pressure and high vacuum via differential pumping for synchrotron radiation applications.

    PubMed

    Gog, T; Casa, D M; Kuzmenko, I; Krakora, R J; Bolin, T B

    2007-07-01

    A differential pump assembly is introduced which can provide a windowless transition between the full atmospheric pressure of an in-air sample environment and the high-vacuum region of a synchrotron radiation beamline, while providing a clear aperture of approximately 1 mm to pass through the X-ray beam from a modern third-generation synchrotron radiation source. This novel pump assembly is meant to be used as a substitute for an exit vacuum window on synchrotron beamlines, where the existence of such a window would negatively impact the coherent nature of the X-ray beam or would introduce parasitic scattering, distorting weak scattering signals from samples under study. It is found that the length of beam pipe necessary to reduce atmospheric pressure to below 10 mbar is only about 130 mm, making the expected photon transmission for hard X-rays through this pipe competitive with that of a regular Be beamline window. This result is due to turbulent flow dominating the first pumping stage, providing a mechanism of strong gas conductance limitation, which is further enhanced by introducing artificial surface roughness in the pipe. Successive reduction of pressure through the transitional flow regime into the high-vacuum region is accomplished over a length of several meters, using beam pipes of increasing diameter. While the pump assembly has not been tested with X-rays, possible applications are discussed in the context of coherent and small-angle scattering. PMID:17587659

  17. 78 FR 1735 - Airworthiness Directives; Honeywell International Inc. Air Data Pressure Transducers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... Executive Order 12866, (2) Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... International Inc. Air Data Pressure Transducers AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... certain Honeywell International Inc. air data pressure transducers as installed on various aircraft....

  18. DESIGN NOTE: Measuring the residual air pressure in triple-point-of-water cells

    NASA Astrophysics Data System (ADS)

    White, D. R.

    2004-01-01

    Residual gas pressure is one of the factors influencing the temperature realized by triple-point-of-water cells. This note describes a simple procedure for measuring and correcting for the residual air pressure in sealed cells. The procedure is applicable to any cell with a McLeod-gauge extension or sufficient remnant 'seal-off' tube to trap an air bubble.

  19. Respiratory and Laryngeal Responses to an Oral Air Pressure Bleed during Speech

    ERIC Educational Resources Information Center

    Huber, Jessica E.; Stathopoulos, Elaine T.

    2003-01-01

    Researchers have hypothesized that the respiratory and laryngeal speech subsystems would respond to an air pressure bleed, but these responses have not been empirically studied. The present study examined the nature of the responses of the respiratory and laryngeal subsystems to an air pressure bleed in order to provide information relevant to the…

  20. Air Pressure Responses to Sudden Vocal Tract Pressure Bleeds during Production of Stop Consonants: New Evidence of Aeromechanical Regulation.

    ERIC Educational Resources Information Center

    Zajac, David J.; Weissler, Mark C.

    2004-01-01

    Two studies were conducted to evaluate short-latency vocal tract air pressure responses to sudden pressure bleeds during production of voiceless bilabial stop consonants. It was hypothesized that the occurrence of respiratory reflexes would be indicated by distinct patterns of responses as a function of bleed magnitude. In Study 1, 19 adults…

  1. Development of a Low Pressure, Air Atomized Oil Burner with High Atomizer Air Flow: Progress Report FY 1997

    SciTech Connect

    Butcher, T.A.

    1998-01-01

    This report describes technical advances made to the concept of a low pressure, air atomized oil burner for home heating applications. Currently all oil burners on the market are of the pressure atomized, retention head type. These burners have a lower firing rate limit of about 0.5 gallons per hour of oil, due to reliability problems related to small flow passage sizes. High pressure air atomized burners have been shown to be one route to avoid this problem but air compressor cost and reliability have practically eliminated this approach. With the low pressure air atomized burner the air required for atomization can be provided by a fan at 5-8 inches of water pressure. A burner using this concept, termed the Fan-Atomized Burner or ''FAB'' has been developed and is currently being commercialized. In the head of the FAB, the combustion air is divided into three parts, much like a conventional retention head burner. This report describes development work on a new concept in which 100% of the air from the fan goes through the atomizer. The primary advantage of this approach is a great simplification of the head design. A nozzle specifically sized for this concept was built and is described in the report. Basic flow pressure tests, cold air velocity profiles, and atomization performance have been measured. A burner head/flame tube has been developed which promotes a toroidal recirculation zone near the nozzle for flame stability. The burner head has been tested in several furnace and boiler applications over the firing rate range 0.2 to 0.28 gallons per hour. In all cases the burner can operate with very low excess air levels (under 10%) without producing smoke. Flue gas NO{sub x} concentration varied from 42 to 62 ppm at 3% O{sub 2}. The concept is seen as having significant potential and planned development efforts are discussed.

  2. The air elimination capabilities of pressure infusion devices and fluid-warmers.

    PubMed

    Schnoor, J; Macko, S; Weber, I; Rossaint, R

    2004-08-01

    Pressurised infusion devices may have only limited capability to detect and remove air during pressurised infusions. In order to assess pressure infusion systems with regard to their actual air elimination capabilities four disposable pressure infusion systems and fluid warmers were investigated: The Level 1 (L-1), Ranger (RA), Gymar (GY), and the Warmflo (WF). Different volumes of air were injected proximal to the heat exchanger and the remaining amount of air that was delivered at the end of the tubing was measured during pressurised infusions. Elimination of the injected air (100-200 ml) was superior by the RA system when compared to L-1 (p < 0.01). The GY and WF systems failed to eliminate the injected air. In conclusion, air elimination was best performed by the RA system. In terms of the risk of air embolism during pressurised infusions, improvements in air elimination of the investigated devices are still necessary. PMID:15270975

  3. Behavior of a horizontal air curtain subjected to a vertical pressure gradient

    NASA Astrophysics Data System (ADS)

    Linden, James; Phelps, LeEllen

    2012-09-01

    We present the details on an experiment to investigate the behavior of an air curtain that is subjected to a transverse pressure gradient. The setup simulates the conditions that will be present in the Advanced Technology Solar Telescope (ATST), a 4-meter solar observatory that will be built on Haleakala, Hawaii. A test rig was built to replicate the region at which the optical path crosses a temperature and pressure boundary between the telescope mount region, which is at the ambient temperature and pressure, and a warmer, pressurized lab space directly below. Use of an air curtain in place of an optically-transmitting window at the interface would allow science observations at a wider range of scientific wavelengths. With the air curtain exhibiting transitional flow behavior across the boundary, and applied pressure gradients of up to 6.5 Pa, we found that the air curtain was able to hold a pressure gradient of 0.25 Pa. As the applied pressure was increased, transient turbulent regions formed at the interface, and predictable flow behavior only occurred in the region closest to the air curtain blower. Computer modeling is used to validate the test data, identify laminar regions of the air curtain where minimal image distortion would occur, and explore the relationship between the applied pressure, effective pressure difference, and air curtain profile.

  4. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Type C supplied-air respirator, demand and pressure... be approved only when used to supply respirable air at the pressures and quantities required. (b) The manufacturer shall specify the range of air pressure at the point of attachment of the air-supply hose to...

  5. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Type C supplied-air respirator, demand and pressure... be approved only when used to supply respirable air at the pressures and quantities required. (b) The manufacturer shall specify the range of air pressure at the point of attachment of the air-supply hose to...

  6. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Type C supplied-air respirator, demand and pressure... be approved only when used to supply respirable air at the pressures and quantities required. (b) The manufacturer shall specify the range of air pressure at the point of attachment of the air-supply hose to...

  7. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Type C supplied-air respirator, demand and pressure... be approved only when used to supply respirable air at the pressures and quantities required. (b) The manufacturer shall specify the range of air pressure at the point of attachment of the air-supply hose to...

  8. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Type C supplied-air respirator, demand and pressure... be approved only when used to supply respirable air at the pressures and quantities required. (b) The manufacturer shall specify the range of air pressure at the point of attachment of the air-supply hose to...

  9. A program to evaluate a control system based on feedback of aerodynamic pressure differentials

    NASA Technical Reports Server (NTRS)

    Levy, D. W.; Finn, P.; Roskam, J.

    1981-01-01

    The use of aerodynamic pressure differentials to position a control surface is evaluated. The system is a differential pressure command loop, analogous to a position command loop, where the surface is commanded to move until a desired differential pressure across the surface is achieved. This type of control is more direct and accurate because it is the differential pressure which causes the control forces and moments. A frequency response test was performed in a low speed wind tunnel to measure the performance of the system. Both pressure and position feedback were tested. The pressure feedback performed as well as position feedback implying that the actuator, with a break frequency on the order of 10 Rad/sec, was the limiting component. Theoretical considerations indicate that aerodynamic lags will not appear below frequencies of 50 Rad/sec, or higher.

  10. High pressure flame system for pollution studies with results for methane-air diffusion flames

    NASA Technical Reports Server (NTRS)

    Miller, I. M.; Maahs, H. G.

    1977-01-01

    A high pressure flame system was designed and constructed for studying nitrogen oxide formation in fuel air combustion. Its advantages and limitations were demonstrated by tests with a confined laminar methane air diffusion flame over the pressure range from 1 to 50 atm. The methane issued from a 3.06 mm diameter port concentrically into a stream of air contained within a 20.5 mm diameter chimney. As the combustion pressure is increased, the flame changes in shape from wide and convex to slender and concave, and there is a marked increase in the amount of luminous carbon. The height of the flame changes only moderately with pressure.

  11. High-pressure combustor exhaust emissions with improved air-atomizing and conventional pressure-atomizing fuel nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.; Norgren, C. T.

    1973-01-01

    A high-pressure combustor segment 0.456 meter (18 in.) long with a maximum cross section of 0.153 by 0.305 meter (6 by 12 in.) was tested with specially designed air-atomizing and conventional pressure-atomizing fuel nozzles at inlet-air temperatures of 340 to 755 k (610 deg to 1360 R), reference velocities of 12.4 to 26.1 meters per second (41 to 86 ft/sec), and fuel-air ratios of 0.008 to 0.020. Increasing inlet-air pressure from 4 to 20 atmospheres generally increased smoke number and nitric oxide, but decreased carbon monoxide and unburned hydrocarbon concentrations with air-atomizing and pressure-atomizing nozzles. Emission indexes for carbon monoxide and unburned hydrocarbons were lower at 4, 10, and 20 atmospheres, and nitric oxide emission indexes were lower at 10 and 20 atmospheres with air-atomizing than with pressure-atomizing nozzles.

  12. Impact of two-way air flow due to temperature difference on preventing the entry of outdoor particles using indoor positive pressure control method.

    PubMed

    Chen, Chun; Zhao, Bin; Yang, Xudong

    2011-02-28

    Maintaining positive pressure indoors using mechanical ventilation system is a popular control method for preventing the entry of outdoor airborne particles. The idea is, as long as the supply air flow rate is larger than return air flow rate, the pressure inside the ventilated room should be positive since the superfluous air flow must exfiltrate from air leakages or other openings of the room to the outdoors. Based on experimental and theoretical analyses this paper aims to show the impact of two-way air flow due to indoor/outdoor temperature difference on preventing the entry of outdoor particles using positive pressure control method. The indoor positive pressure control method is effective only when the size of the opening area is restricted to a certain level, opening degree less than 30° in this study, due to the two-way air flow effect induced by differential temperature. The theoretical model was validated using the experimental data. The impacts of two-way air flow due to temperature difference and the supply air flow rate were also analyzed using the theoretical model as well as experimental data. For real houses, it seems that the idea about the positive pressure control method for preventing the entry of outdoor particles has a blind side.

  13. Method and apparatus for measuring mass flow and energy content using a differential pressure meter

    SciTech Connect

    Vander Heyden, W.H.

    1993-07-13

    An apparatus is described for measuring a ratio of a mass flow rate of a pipeline gas flowing through a pipeline compared to a mass flow rate of a sample gas tapped from the pipeline, the pipeline having a first device means for producing a pipeline gas pressure differential, the apparatus comprising: a second device means for producing a sample gas pressure differential while maintaining the sample gas at substantially the same temperature as the pipeline gas; means for routing the sample gas to the second device means; means for measuring the pipeline gas pressure differential as the pipeline gas flows through the first device means; means for measuring the sample gas pressure differential as the sample gas flows through the second device means; a flow controlling means located downstream of the second device means for maintaining a sample gas flow rate through the second device means independent of the pipeline gas pressure differential; and a control means for comparing the sample gas pressure differential with the pipeline gas pressure differential in order to obtain the mass flow rate ratio. A method is described for using the above apparatus.

  14. Air Circulation and Heat Exchange Under Reduced Pressures

    NASA Technical Reports Server (NTRS)

    Rygalov, V.; Wheeler, R.; Dixon, M.; Fowler, P.; Hillhouse, L.

    2010-01-01

    Heat exchange rates decrease non-linearly with reductions in atmospheric pressure. This decrease creates risk of thermal stress (elevated leaf temperatures) for plants under reduced pressures. Forced convection (fans) significantly increases heat exchange rate under almost all pressures except below 10 kPa. Plant cultivation techniques under reduced pressures will require forced convection. The cooling curve technique is a reliable means of assessing the influence of environmental variables like pressure and gravity on gas exchange of plant. These results represent the extremes of gas exchange conditions for simple systems under variable pressures. In reality, dense plant canopies will exhibit responses in between these extremes. More research is needed to understand the dependence of forced convection on atmospheric pressure. The overall thermal balance model should include latent and radiative exchange components.

  15. Insect hygroreceptor responses to continuous changes in humidity and air pressure.

    PubMed

    Tichy, H; Kallina, W

    2010-06-01

    The most favored model of humidity transduction views the cuticular wall of insect hygroreceptive sensilla as a hygromechanical transducer. Hygroscopic swelling or shrinking alters the geometry of the wall, deforming the dendritic membranes of the moist and dry cells. The small size the sensilla and their position surrounded by elevated structures creates technical difficulties to mechanically stimulate them by direct contact. The present study investigated hygroreceptors on the antennae of the cockroach and the stick insect. Accurately controlled, homogeneous mechanical input was delivered by modulating air pressure. Both the moist and dry cells responded not only to changes in air pressure but also in the opposite direction, as observed during changes in air humidity. The moist cell's excitatory response to increasing humidity and increasing air pressure implies that swelling of the hygroscopic cuticle compresses the dendrites, and the dry cell's excitatory response to decreasing humidity and decreasing air pressure implies that shrinking of the hygroscopic cuticle expands the dendrites. The moist and dry cells of the stick insect are more sensitive to pressure changes than those of the cockroach, but the responses to air pressure are generally weaker than to humidity. Therefore the hygroreceptive sensilla differ in their physical properties and constitutions. Furthermore, the mechanical parameters associated with homogeneous changes in air pressure on the sensillum surface can only partially account for the responses of the moist and dry cells of both species to humidity stimulation. PMID:20375249

  16. Insect hygroreceptor responses to continuous changes in humidity and air pressure

    PubMed Central

    Tichy, H.; Kallina, W.

    2011-01-01

    The most favored model of humidity transduction views the cuticular wall of insect hygroreceptive sensilla as a hygromechanical transducer. Hygroscopic swelling or shrinking alters the geometry of the wall, deforming the dendritic membranes of the moist and dry cells. The small size the sensilla and their position surrounded by elevated structures creates technical difficulties to mechanically stimulate them by direct contact. The present study investigated hygroreceptors on the antennae of the cockroach and the stick insect. Accurately controlled, homogeneous mechanical input was delivered by modulating air pressure. Both the moist and dry cells responded not only to changes in air pressure, but also in the opposite direction, as observed during changes in air humidity. The moist-cell’s excitatory response to increasing humidity and increasing air pressure implies that swelling of the hygroscopic cuticle compresses the dendrites, and the dry-cell’s excitatory response to decreasing humidity and decreasing air pressure implies that shrinking of the hygroscopic cuticle expands the dendrites. The moist and dry cells of the stick insect are more sensitive to pressure changes than those of the cockroach, but the responses to air pressure are generally weaker than to humidity. Therefore, the hygroreceptive sensilla differ in their physical properties and constitutions. Furthermore, the mechanical parameters associated with homogeneous changes in air pressure on the sensillum surface can only partially account for the responses of the moist and dry cells of both species to humidity stimulation. PMID:20375249

  17. Spatial Characteristics of the Unsteady Differential Pressures on 16 percent F/A-18 Vertical Tails

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.; Ashley, Holt

    1998-01-01

    Buffeting is an aeroelastic phenomenon which plagues high performance aircraft at high angles of attack. For the F/A-18 at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their turbulent wake. The resulting buffeting of the vertical tails is a concern from fatigue and inspection points of view. Previous flight and wind-tunnel investigations to determine the buffet loads on the tail did not provide a complete description of the spatial characteristics of the unsteady differential pressures. Consequently, the unsteady differential pressures were considered to be fully correlated in the analyses of buffet and buffeting. The use of fully correlated pressures in estimating the generalized aerodynamic forces for the analysis of buffeting yielded responses that exceeded those measured in flight and in the wind tunnel. To learn more about the spatial characteristics of the unsteady differential pressures, an available 16%, sting-mounted, F-18 wind-tunnel model was modified and tested in the Transonic Dynamics Tunnel (TDT) at the NASA Langley Research Center as part of the ACROBAT (Actively Controlled Response Of Buffet-Affected Tails) program. Surface pressures were measured at high angles of attack on flexible and rigid tails. Cross-correlation and cross-spectral analyses of the pressure time histories indicate that the unsteady differential pressures are not fully correlated. In fact, the unsteady differential pressure resemble a wave that travels along the tail. At constant angle of attack, the pressure correlation varies with flight speed.

  18. Velocity and pressure distribution behind bodies in an air current

    NASA Technical Reports Server (NTRS)

    Betz, A

    1924-01-01

    The following experiments on the air flow behind bodies were made for the purpose of assisting in the explanation of the phenomena connected with air resistance. The first two series of experiments dealt with the phenomena behind a cylinder. The third series of experiments was carried out behind a streamlined strut.

  19. An objective definition of air mass types affecting Athens, Greece; the corresponding atmospheric pressure patterns and air pollution levels.

    PubMed

    Sindosi, O A; Katsoulis, B D; Bartzokas, A

    2003-08-01

    This work aims at defining characteristic air mass types that dominate in the region of Athens, Greece during the cold (November-March) and the warm (May-September) period of the year and also at evaluating the corresponding concentration levels of the main air pollutants. For each air mass type, the mean atmospheric pressure distribution (composite maps) over Europe and the Mediterranean is estimated in order to reveal the association of atmospheric circulation with air pollution levels in Athens. The data basis for this work consists of daily values of thirteen meteorological and six pollutant parameters covering the period 1993-97. The definition of the characteristic air mass types is attempted objectively by using the methods of Factor Analysis and Cluster Analysis. The results show that during the cold period of the year there are six prevailing air mass types (at least 3% of the total number of days) and six infrequent ones. The examination of the corresponding air pollution concentration levels shows that the primary air pollutants appear with increased concentrations when light or southerly winds prevail. This is usually the case when a high pressure system is located over the central Mediterranean or a low pressure system lays over south Italy, respectively. Low levels of the primary pollutants are recorded under northeasterly winds, mainly caused by a high pressure system over Ukraine. During the warm period of the year, the southwestern Asia thermal low and the subtropical anticyclone of the Atlantic Ocean affect Greece. Though these synoptic systems cause almost stagnant conditions, four main air mass types are dominant and ten others, associated with extreme weather, are infrequent. Despite the large amounts of total solar radiation characterizing this period, ozone concentrations remain at low levels in central Athens because of its destruction by nitric oxide.

  20. Aire Expression Is Inherent to Most Medullary Thymic Epithelial Cells during Their Differentiation Program.

    PubMed

    Kawano, Hiroshi; Nishijima, Hitoshi; Morimoto, Junko; Hirota, Fumiko; Morita, Ryoko; Mouri, Yasuhiro; Nishioka, Yasuhiko; Matsumoto, Mitsuru

    2015-12-01

    Aire in medullary thymic epithelial cells (mTECs) plays an important role in the establishment of self-tolerance. Because Aire(+) mTECs appear to be a limited subset, they may constitute a unique lineage(s) among mTECs. An alternative possibility is that all mTECs are committed to express Aire in principle, but Aire expression by individual mTECs is conditional. To investigate this issue, we established a novel Aire reporter strain in which endogenous Aire is replaced by the human AIRE-GFP-Flag tag (Aire/hAGF-knockin) fusion gene. The hAGF reporter protein was produced and retained very efficiently within mTECs as authentic Aire nuclear dot protein. Remarkably, snapshot analysis revealed that mTECs expressing hAGF accounted for >95% of mature mTECs, suggesting that Aire expression does not represent a particular mTEC lineage(s). We confirmed this by generating Aire/diphtheria toxin receptor-knockin mice in which long-term ablation of Aire(+) mTECs by diphtheria toxin treatment resulted in the loss of most mature mTECs beyond the proportion of those apparently expressing Aire. These results suggest that Aire expression is inherent to all mTECs but may occur at particular stage(s) and/or cellular states during their differentiation, thus accounting for the broad impact of Aire on the promiscuous gene expression of mTECs.

  1. Method and apparatus for monitoring oxygen partial pressure in air masks

    NASA Technical Reports Server (NTRS)

    Kelly, Mark E. (Inventor); Pettit, Donald R. (Inventor)

    2006-01-01

    Method and apparatus are disclosed for monitoring an oxygen partial pressure in an air mask and providing a tactile warning to the user. The oxygen partial pressure in the air mask is detected using an electrochemical sensor, the output signal from which is provided to a comparator. The comparator compares the output signal with a preset reference value or range of values representing acceptable oxygen partial pressures. If the output signal is different than the reference value or outside the range of values, the air mask is vibrated by a vibrating motor to alert the user to a potentially hypoxic condition.

  2. Control of an Isolated Table's Fluctuation Caused by Supplied Air Pressure Using a Voice Coil Motor

    NASA Astrophysics Data System (ADS)

    Shirani, Habiburahman; Wakui, Shinji

    Pneumatic type anti-vibration apparatuses are used in the field of semiconductor manufacturing and precision measurement. The variation of the supplied air pressure from the air compressor causes the position fluctuation of the isolated table. A control method using a voice coil motor (VCM) as the actuator is proposed in this study to control the position fluctuation of the isolated table caused by the supplied air pressure. The feedforward compensator control scheme is used to provide a proper controlled signal to the VCM. According to the controlled signal, VCM exerts driving force in the opposite direction of the air spring expansion or compression to suppress the vibration of the isolated table.

  3. Endotracheal tube cuff pressure before, during, and after fixed-wing air medical retrieval.

    PubMed

    Brendt, Peter; Schnekenburger, Marc; Paxton, Karen; Brown, Anthony; Mendis, Kumara

    2013-01-01

    Abstract Background. Increased endotracheal tube (ETT) cuff pressure is associated with compromised tracheal mucosal perfusion and injuries. No published data are available for Australia on pressures in the fixed-wing air medical retrieval setting. Objective. After introduction of a cuff pressure manometer (Mallinckrodt, Hennef, Germany) at the Royal Flying Doctor Service (RFDS) Base in Dubbo, New South Wales (NSW), Australia, we assessed the prevalence of increased cuff pressures before, during, and after air medical retrieval. Methods. This was a retrospective audit in 35 ventilated patients during fixed-wing retrievals by the RFDS in NSW, Australia. Explicit chart review of ventilated patients was performed for cuff pressures and changes during medical retrievals with pressurized aircrafts. Pearson correlation was calculated to determine the relation of ascent and ETT cuff pressure change from ground to flight level. Results. The mean (± standard deviation) of the first ETT cuff pressure measurement on the ground was 44 ± 20 cmH2O. Prior to retrieval in 11 patients, the ETT cuff pressure was >30 cmH2O and in 11 patients >50 cmH2O. After ascent to cruising altitude, the cuff pressure was >30 cmH2O in 22 patients and >50 cmH2O in eight patients. The cuff pressure was reduced 1) in 72% of cases prior to take off and 2) in 85% of cases during flight, and 3) after landing, the cuff pressure increased in 85% of cases. The correlation between ascent in cabin altitude and ETT cuff pressure was r = 0.3901, p = 0.0205. Conclusions. The high prevalence of excessive cuff pressures during air medical retrieval can be avoided by the use of cuff pressure manometers. Key words: cuff pressure; air medical retrieval; prehospital. PMID:23252881

  4. Endotracheal tube cuff pressure before, during, and after fixed-wing air medical retrieval.

    PubMed

    Brendt, Peter; Schnekenburger, Marc; Paxton, Karen; Brown, Anthony; Mendis, Kumara

    2013-01-01

    Abstract Background. Increased endotracheal tube (ETT) cuff pressure is associated with compromised tracheal mucosal perfusion and injuries. No published data are available for Australia on pressures in the fixed-wing air medical retrieval setting. Objective. After introduction of a cuff pressure manometer (Mallinckrodt, Hennef, Germany) at the Royal Flying Doctor Service (RFDS) Base in Dubbo, New South Wales (NSW), Australia, we assessed the prevalence of increased cuff pressures before, during, and after air medical retrieval. Methods. This was a retrospective audit in 35 ventilated patients during fixed-wing retrievals by the RFDS in NSW, Australia. Explicit chart review of ventilated patients was performed for cuff pressures and changes during medical retrievals with pressurized aircrafts. Pearson correlation was calculated to determine the relation of ascent and ETT cuff pressure change from ground to flight level. Results. The mean (± standard deviation) of the first ETT cuff pressure measurement on the ground was 44 ± 20 cmH2O. Prior to retrieval in 11 patients, the ETT cuff pressure was >30 cmH2O and in 11 patients >50 cmH2O. After ascent to cruising altitude, the cuff pressure was >30 cmH2O in 22 patients and >50 cmH2O in eight patients. The cuff pressure was reduced 1) in 72% of cases prior to take off and 2) in 85% of cases during flight, and 3) after landing, the cuff pressure increased in 85% of cases. The correlation between ascent in cabin altitude and ETT cuff pressure was r = 0.3901, p = 0.0205. Conclusions. The high prevalence of excessive cuff pressures during air medical retrieval can be avoided by the use of cuff pressure manometers. Key words: cuff pressure; air medical retrieval; prehospital.

  5. Firefighter's compressed air breathing system pressure vessel development program

    NASA Technical Reports Server (NTRS)

    Beck, E. J.

    1974-01-01

    The research to design, fabricate, test, and deliver a pressure vessel for the main component in an improved high-performance firefighter's breathing system is reported. The principal physical and performance characteristics of the vessel which were required are: (1) maximum weight of 9.0 lb; (2) maximum operating pressure of 4500 psig (charge pressure of 4000 psig); (3) minimum contained volume of 280 in. 3; (4) proof pressure of 6750 psig; (5) minimum burst pressure of 9000 psig following operational and service life; and (6) a minimum service life of 15 years. The vessel developed to fulfill the requirements described was completely sucessful, i.e., every category of performence was satisfied. The average weight of the vessel was found to be about 8.3 lb, well below the 9.0 lb specification requirement.

  6. Scoping decision document for HEPA filter differential pressure interlock control installation and tank farm exhauster operation

    SciTech Connect

    GUSTAVSON, R.D.

    2001-06-27

    This document is a decision document regarding the scope of HEPA filter differential pressure interlock system installations at Tank Farm emission units. It is intended to provide supporting information for administration of Baseline Change Request.

  7. A directional cylindrical anemometer with four sets of differential pressure sensors

    NASA Astrophysics Data System (ADS)

    Liu, C.; Du, L.; Zhao, Z.

    2016-03-01

    This paper presents a solid-state directional anemometer for simultaneously measuring the speed and direction of a wind in a plane in a speed range 1-40 m/s. This instrument has a cylindrical shape and works by detecting the pressure differences across diameters of the cylinder when exposed to wind. By analyzing our experimental data in a Reynolds number regime 1.7 × 103-7 × 104, we figure out the relationship between the pressure difference distribution and the wind velocity. We propose a novel and simple solution based on the relationship and design an anemometer which composes of a circular cylinder with four sets of differential pressure sensors, tubes connecting these sensors with the cylinder's surface, and corresponding circuits. In absence of moving parts, this instrument is small and immune of friction. It has simple internal structures, and the fragile sensing elements are well protected. Prototypes have been fabricated to estimate performance of proposed approach. The power consumption of the prototype is less than 0.5 W, and the sample rate is up to 31 Hz. The test results in a wind tunnel indicate that the maximum relative speed measuring error is 5% and the direction error is no more than 5° in a speed range 2-40 m/s. In theory, it is capable of measuring wind up to 60 m/s. When the air stream goes slower than 2 m/s, the measuring errors of directions are slightly greater, and the performance of speed measuring degrades but remains in an acceptable range of ±0.2 m/s.

  8. A directional cylindrical anemometer with four sets of differential pressure sensors.

    PubMed

    Liu, C; Du, L; Zhao, Z

    2016-03-01

    This paper presents a solid-state directional anemometer for simultaneously measuring the speed and direction of a wind in a plane in a speed range 1-40 m/s. This instrument has a cylindrical shape and works by detecting the pressure differences across diameters of the cylinder when exposed to wind. By analyzing our experimental data in a Reynolds number regime 1.7 × 10(3)-7 × 10(4), we figure out the relationship between the pressure difference distribution and the wind velocity. We propose a novel and simple solution based on the relationship and design an anemometer which composes of a circular cylinder with four sets of differential pressure sensors, tubes connecting these sensors with the cylinder's surface, and corresponding circuits. In absence of moving parts, this instrument is small and immune of friction. It has simple internal structures, and the fragile sensing elements are well protected. Prototypes have been fabricated to estimate performance of proposed approach. The power consumption of the prototype is less than 0.5 W, and the sample rate is up to 31 Hz. The test results in a wind tunnel indicate that the maximum relative speed measuring error is 5% and the direction error is no more than 5° in a speed range 2-40 m/s. In theory, it is capable of measuring wind up to 60 m/s. When the air stream goes slower than 2 m/s, the measuring errors of directions are slightly greater, and the performance of speed measuring degrades but remains in an acceptable range of ±0.2 m/s. PMID:27036817

  9. A directional cylindrical anemometer with four sets of differential pressure sensors.

    PubMed

    Liu, C; Du, L; Zhao, Z

    2016-03-01

    This paper presents a solid-state directional anemometer for simultaneously measuring the speed and direction of a wind in a plane in a speed range 1-40 m/s. This instrument has a cylindrical shape and works by detecting the pressure differences across diameters of the cylinder when exposed to wind. By analyzing our experimental data in a Reynolds number regime 1.7 × 10(3)-7 × 10(4), we figure out the relationship between the pressure difference distribution and the wind velocity. We propose a novel and simple solution based on the relationship and design an anemometer which composes of a circular cylinder with four sets of differential pressure sensors, tubes connecting these sensors with the cylinder's surface, and corresponding circuits. In absence of moving parts, this instrument is small and immune of friction. It has simple internal structures, and the fragile sensing elements are well protected. Prototypes have been fabricated to estimate performance of proposed approach. The power consumption of the prototype is less than 0.5 W, and the sample rate is up to 31 Hz. The test results in a wind tunnel indicate that the maximum relative speed measuring error is 5% and the direction error is no more than 5° in a speed range 2-40 m/s. In theory, it is capable of measuring wind up to 60 m/s. When the air stream goes slower than 2 m/s, the measuring errors of directions are slightly greater, and the performance of speed measuring degrades but remains in an acceptable range of ±0.2 m/s.

  10. Influence of air pressure on the performance of plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

    Li, Yang; Jia, Min; Wu, Yun; Li, Ying-hong; Zong, Hao-hua; Song, Hui-min; Liang, Hua

    2016-09-01

    Plasma synthetic jet actuator (PSJA) has a wide application prospect in the high-speed flow control field for its high jet velocity. In this paper, the influence of the air pressure on the performance of a two-electrode PSJA is investigated by the schlieren method in a large range from 7 kPa to 100 kPa. The energy consumed by the PSJA is roughly the same for all the pressure levels. Traces of the precursor shock wave velocity and the jet front velocity vary a lot for different pressures. The precursor shock wave velocity first decreases gradually and then remains at 345 m/s as the air pressure increases. The peak jet front velocity always appears at the first appearance of a jet, and it decreases gradually with the increase of the air pressure. A maximum precursor shock wave velocity of 520 m/s and a maximum jet front velocity of 440 m/s are observed at the pressure of 7 kPa. The averaged jet velocity in one period ranges from 44 m/s to 54 m/s for all air pressures, and it drops with the rising of the air pressure. High velocities of the precursor shock wave and the jet front indicate that this type of PSJA can still be used to influence the high-speed flow field at 7 kPa. Project supported by the National Natural Science Foundation of China (Grant Nos. 51407197, 51522606, 51336011, 91541120, and 11472306).

  11. MEASUREMENT OF FRICTIONAL PRESSURE DIFFERENTIALS DURING A VENTILATION SURVEY

    SciTech Connect

    B.S. Prosser, PE; I.M. Loomis, PE, PhD

    2003-11-03

    During the course of a ventilation survey, both airflow quantity and frictional pressure losses are measured and quantified. The measurement of airflow has been extensively studied as the vast majority of ventilation standards/regulations are tied to airflow quantity or velocity. However, during the conduct of a ventilation survey, measurement of airflow only represents half of the necessary parameters required to directly calculate the airway resistance. The measurement of frictional pressure loss is an often misunderstood and misapplied part of the ventilation survey. This paper compares the two basic methods of frictional pressure drop measurements; the barometer and the gauge and tube. Personal experiences with each method will be detailed along with the authors' opinions regarding the applicability and conditions favoring each method.

  12. Acceptance test report, inlet air filter and control station pressure decay leak test

    SciTech Connect

    Tuck, J.A., Fluor Daniel Hanford

    1997-02-11

    This is the acceptance test report for pressure decay leak tests performed on Tank Farm primary ventilation system inlet air filter and control stations, following their installation in the field and prior to acceptance for beneficial use.

  13. Prosthetics socket that incorporates an air splint system focusing on dynamic interface pressure

    PubMed Central

    2014-01-01

    Background The interface pressure between the residual limb and prosthetic socket has a significant effect on an amputee’s satisfaction and comfort. This paper presents the design and performance of a new prosthetic socket that uses an air splint system. Methods The air splint prosthetic socket system was implemented by combining the air splint with a pressure sensor that the transhumeral user controls through the use of a microcontroller. The modular construction of the system developed allows the FSR pressure sensors that are placed inside the air splint socket to determine the required size and fitting for the socket used. Fifteen transhumeral amputees participated in the study. Results The subject’s dynamic pressure on the socket that’s applied while wearing the air splint systems was recorded using F-socket transducers and microcontroller analysis. The values collected by the F-socket sensor for the air splint prosthetic socket system were determined accordingly by comparing the dynamic pressure applied using statically socket. The pressure volume of the air splint fluctuated and was recorded at an average of 38 kPa (2.5) to 41 kPa (1.3) over three hours. Conclusion The air splint socket might reduce the pressure within the interface of residual limb. This is particularly important during the daily life activities and may reduce the pain and discomfort at the residual limb in comparison to the static socket. The potential development of an auto-adjusted socket that uses an air splint system as the prosthetic socket will be of interest to researchers involved in rehabilitation engineering, prosthetics and orthotics. PMID:25085005

  14. The rate of pressure rise of gaseous propylene-air explosions in spherical and cylindrical enclosures.

    PubMed

    Razus, Domnina; Movileanua, Codina; Oancea, Dumitru

    2007-01-01

    The maximum rates of pressure rise of propylene-air explosions at various initial pressures and various fuel/oxygen ratios in three closed vessels (a spherical vessel with central ignition and two cylindrical vessels with central or with top ignition) are reported. It was found that in explosions of quiescent mixtures the maximum rates of pressure rise are linear functions on total initial pressure, at constant initial temperature and fuel/oxygen ratio. The slope and intercept of found correlations are greatly influenced by vessel's volume and shape and by the position of the ignition source--factors which determine the amount of heat losses from the burned gas in a closed vessel explosion. Similar data on propylene-air inert mixtures are discussed in comparison with those referring to propylene-air, revealing the influence of nature and amount of inert additive. The deflagration index KG of centrally ignited explosions was also calculated from maximum rates of pressure rise. PMID:16876946

  15. The rate of pressure rise of gaseous propylene-air explosions in spherical and cylindrical enclosures.

    PubMed

    Razus, Domnina; Movileanua, Codina; Oancea, Dumitru

    2007-01-01

    The maximum rates of pressure rise of propylene-air explosions at various initial pressures and various fuel/oxygen ratios in three closed vessels (a spherical vessel with central ignition and two cylindrical vessels with central or with top ignition) are reported. It was found that in explosions of quiescent mixtures the maximum rates of pressure rise are linear functions on total initial pressure, at constant initial temperature and fuel/oxygen ratio. The slope and intercept of found correlations are greatly influenced by vessel's volume and shape and by the position of the ignition source--factors which determine the amount of heat losses from the burned gas in a closed vessel explosion. Similar data on propylene-air inert mixtures are discussed in comparison with those referring to propylene-air, revealing the influence of nature and amount of inert additive. The deflagration index KG of centrally ignited explosions was also calculated from maximum rates of pressure rise.

  16. Electrical explosion of Al and Ag wires in air at different pressures

    NASA Astrophysics Data System (ADS)

    Sarkisov, G. S.; Caplinger, J.; Parada, F.; Sotnikov, V. I.

    2016-09-01

    Experiments with electrically exploding fine Al and Ag wires in air demonstrate a strong dependence of the expanding metal core condition and velocity on ambient pressure. Expansion velocity of the wire core varies by 23 times between ˜0.2 km/s and ˜4.6 km/s. The shock-wave velocity at atmospheric pressure is ˜5 km/s and increases to ˜6 km/s when the pressure is decreased to 50 Torr. The condition of the metal core is strongly dependent on material and whether it is expanding into vacuum or against ambient air pressure. Expansion velocity of the fine Al and Ag wires for different surrounding pressures in general agree with Paschen's Law for air gap.

  17. Enhanced heterologous protein production in Pichia pastoris under increased air pressure.

    PubMed

    Lopes, Marlene; Oliveira, Carla; Domingues, Lucília; Mota, Manuel; Belo, Isabel

    2014-01-01

    Pichia pastoris is a widely used host for the production of heterologous proteins. In this case, high cell densities are needed and oxygen is a major limiting factor. The increased air pressure could be used to improve the oxygen solubility in the medium and to reach the high oxygen demand of methanol metabolism. In this study, two P. pastoris strains producing two different recombinant proteins, one intracellular (β-galactosidase) and other extracellular (frutalin), were used to investigate the effect of increased air pressure on yeast growth in glycerol and heterologous protein production, using the methanol AOX1-inducible system. Experiments were carried out in a stainless steel bioreactor under total air pressure of 1 bar and 5 bar. The use of an air pressure raise of up to 5 bar proved to be applicable for P. pastoris cultivation. Moreover, no effects on the kinetic growth parameters and methanol utilization (Mut) phenotype of strains were found, while an increase in recombinant β-galactosidase-specific activity (ninefold) and recombinant frutalin production was observed. Furthermore, the air pressure raise led to a reduction in the secreted protease specific activity. This work shows for the first time that the application of an air pressure of 5 bar may be used as a strategy to decrease protease secretion and improve recombinant protein production in P. pastoris.

  18. Atmospheric pressure and temperature profiling using near IR differential absorption lidar

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Weng, C. Y.

    1983-01-01

    The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.

  19. Response of pulmonary veins to increased intracranial pressure and pulmonary air embolization

    SciTech Connect

    Peterson, B.T.; Grauer, S.E.; Hyde, R.W.; Ortiz, C.; Moosavi, H.; Utell, M.J.

    1980-01-01

    To see whether air emboli to the lungs rather than brain compression caused these findings, anesthetized dogs received intravenous air infusions, subdural air infusions, or brain compression from balloons inflated in the subdural space. Subdural air and intravenous air resulted in similar vascular responses. Pulmonary artery pressure (Ppa) increased 160% (P < 0.01) and pulmonary venous pressure transiently rose 13 +- 5 Torr (P < 0.05) without an increase in left atrial pressure or cardiac output (Q). The end-tidal PCP/sub 2/ fell 55% (P < 0.01) and the postmortem weight of the lungs increased 55% (P < 0.05). Brain compression with a subdural balloon instead of air only caused a 20% rise in Ppa and Q without pulmonary edema. Thus, pulmonary air emboli rather than brain compression accounts for the edema and pulmonary hypertension caused by subdural air. Catheters in pulmonary veins and the left atrium showed that air emboli cause transient pulmonary venous hypertension as well as a reproducible form of noncardiogenic pulmonary edema.

  20. A program to evaluate a control system based on feedback of aerodynamic pressure differentials, part 1

    NASA Technical Reports Server (NTRS)

    Hrabak, R. R.; Levy, D. W.; Finn, P.; Roskam, J.

    1981-01-01

    The use of pressure differentials in a flight control system was evaluated. The pressure profile around the test surface was determined using two techniques: (1) windtunnel data (actual); and (2) NASA/Langley Single Element Airfoil Computer Program (theoretical). The system designed to evaluate the concept of using pressure differentials is composed of a sensor drive and power amplifiers, actuator, position potentiometer, and a control surface. The characteristics (both desired and actual) of the system and each individual component were analyzed. The desired characteristics of the system as a whole are given. The flight control system developed, the testing procedures and data reduction methods used, and theoretical frequency response analysis are described.

  1. Further experiments on the stability of laminar and turbulent hydrogen-air flames at reduced pressures

    NASA Technical Reports Server (NTRS)

    Fine, Burton

    1957-01-01

    Stability limits for laminar and turbulent hydrogen-air burner flames were measured as a function of pressure, burner diameter, and composition. On the basis of a simple flame model, turbulent flashback involved a smaller effective penetration distance than laminar flashback. No current theoretical treatment predicts the observed pressure and diameter dependence of laminar and turbulent blowoff.

  2. Pressure Distribution and Air Data System for the Aeroassist Flight Experiment

    NASA Technical Reports Server (NTRS)

    Gibson, Lorelei S.; Siemers, Paul M., III; Kern, Frederick A.

    1989-01-01

    The Aeroassist Flight Experiment (AFE) is designed to provide critical flight data necessary for the design of future Aeroassist Space Transfer Vehicles (ASTV). This flight experiment will provide aerodynamic, aerothermodynamic, and environmental data for verification of experimental and computational flow field techniques. The Pressure Distribution and Air Data System (PD/ADS), one of the measurement systems incorporated into the AFE spacecraft, is designed to provide accurate pressure measurements on the windward surface of the vehicle. These measurements will be used to determine the pressure distribution and air data parameters (angle of attack, angle of sideslip, and free-stream dynamic pressure) encountered by the blunt-bodied vehicle over an altitude range of 76.2 km to 94.5 km. Design and development data are presented and include: measurement requirements, measurement heritage, theoretical studies to define the vehicle environment, flush-mounted orifice configuration, pressure transducer selection and performance evaluation data, and pressure tubing response analysis.

  3. Variation of the pressure limits of flame propagation with tube diameter for propane-air mixtures

    NASA Technical Reports Server (NTRS)

    Belles, Frank E; Simon, Dorothy M

    1951-01-01

    An investigation was made of the variation of the pressure limits of flame propagation with tube diameter for quiescent propane with tube diameter for quiescent propane-air mixtures. Pressure limits were measured in glass tubes of six different inside diameters, with a precise apparatus. Critical diameters for flame propagation were calculated and the effect of pressure was determined. The critical diameters depended on the pressure to the -0.97 power for stoichiometric mixtures. The pressure dependence decreased with decreasing propane concentration. Critical diameters were related to quenching distance, flame speeds, and minimum ignition energy.

  4. An experimental study of geyser-like flows induced by a pressurized air pocket

    NASA Astrophysics Data System (ADS)

    Elayeb, I. S.; Leon, A.; Choi, Y.; Alnahit, A. O.

    2015-12-01

    Previous studies argues that the entrapment of pressurized air pockets within combined sewer systems can produce geyser flows, which is an oscillating jetting of a mixture of gas-liquid flows. To verify that pressurized air pockets can effectively produce geysers, laboratory experiments were conducted. However, past experiments were conducted in relatively small-scale apparatus (i.e. maximum φ2" vertical shaft). This study conducted a set of experiments in a larger apparatus. The experimental setup consists of an upstream head tank, a downstream head tank, a horizontal pipe (46.5ft long, φ6") and a vertical pipe (10ft long, φ6"). The initial condition for the experiments is constant flow discharge through the horizontal pipe. The experiments are initiated by injecting an air pocket with pre-determined volume and pressure at the upstream end of the horizontal pipe. The air pocket propagates through the horizontal pipe until it arrives to the vertical shaft, where it is released producing a geyser-like flow. Three flow rates in the horizontal pipe and three injected air pressures were tested. The variables measured were pressure at two locations in the horizontal pipe and two locations in the vertical pipe. High resolution videos at two regions in the vertical shaft were also recorded. To gain further insights in the physics of air-water interaction, the laboratory experiments were complemented with numerical simulations conducted using a commercial 3D CFD model, previously validated with experiments.

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

    SciTech Connect

    Desantes, J.M.; Galindo, J.; Guardiola, C.; Dolz, V.

    2010-01-15

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

  6. Aerodynamic effect of combustor inlet-air pressure on fuel jet atomization

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1984-01-01

    Mean drop diameters were measured with a recently developed scanning radiometer in a study of the atomization of liquid jets injected cross stream in high velocity and high pressure airflows. At constant inlet air pressure, reciprocal mean drop diameter, was correlated with airflow mass velocity. Over a combustor inlet-air pressure range of 1 to 21 atmospheres, the ratio of orifice to mean drop diameter, D(O)/D(M), was correlated with the product of Weber and Reynolds number, WeRe, and with the molecular scale momentum transfer ratio of gravitational to inertial forces.

  7. Aerodynamic effect of combustor inlet-air pressure on fuel jet atomization

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1984-01-01

    Mean drop diameters were measured with a recently developed scanning radiometer in a study of the atomization of liquid jets injected cross stream in high velocity and high pressure airflows. At constant inlet air pressure, reciprocal mean drop diameter was correlated with airflow mass velocity. Over a combustor inlet-air pressure range of 1 to 21 atmospheres, the ratio of orifice to mean drop diameter, D(O)/D(M), was correlated with the product of Weber and Reynolds number, WeRe, and with the molecular scale momentum transfer ratio of gravitational to inertial forces. Previously announced in STAR as N84-22910

  8. Plain-jet airblast atomization of alternative liquid petroleum fuels under high ambient air pressure conditions

    NASA Astrophysics Data System (ADS)

    Jasuja, A. K.

    1982-04-01

    The effects that air and fuel properties have upon the spray mean drop size characteristics of a plain-jet airblast atomizer of the type employed in the gas turbine engine are investigated. The tests used kerosene, gas oil and a high-viscosity blend of gas oil in residual fuel oil, and covered a wide range of ambient air pressures. Laser light-scattering technique was employed for drop size measurements. It is concluded that the atomizer's measured mean drop size characteristics are only slightly different from those of the pre-filming type, especially when operating on low-viscosity kerosene under higher ambient air pressure. The beneficial effect of increased levels of ambient air pressure on mean drop size is shown to be much reduced in the case of high-viscosity fuels, thus making the attainment of good atomization performance on such fuels difficult. An expression is derived for correlating the obtained mean drop size data.

  9. Intercooler cooling-air weight flow and pressure drop for minimum drag loss

    NASA Technical Reports Server (NTRS)

    Reuter, J George; Valerino, Michael F

    1944-01-01

    An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

  10. Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a slot air jet

    NASA Astrophysics Data System (ADS)

    Adimurthy, M.; Katti, Vadiraj V.

    2016-06-01

    Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing (Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio (l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.

  11. Numerical simulation of high pressure release and dispersion of hydrogen into air with real gas model

    NASA Astrophysics Data System (ADS)

    Khaksarfard, R.; Kameshki, M. R.; Paraschivoiu, M.

    2010-06-01

    Hydrogen is a renewable and clean source of energy, and it is a good replacement for the current fossil fuels. Nevertheless, hydrogen should be stored in high-pressure reservoirs to have sufficient energy. An in-house code is developed to numerically simulate the release of hydrogen from a high-pressure tank into ambient air with more accuracy. Real gas models are used to simulate the flow since high-pressure hydrogen deviates from ideal gas law. Beattie-Bridgeman and Abel Noble equations are applied as real gas equation of state. A transport equation is added to the code to calculate the concentration of the hydrogen-air mixture after release. The uniqueness of the code is to simulate hydrogen in air release with the real gas model. Initial tank pressures of up to 70 MPa are simulated.

  12. Differential absorption lidar technique for measurement of the atmospheric pressure profile

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Weng, C. Y.

    1983-01-01

    A new two-wavelength lidar technique for remotely measuring the pressure profile using the trough absorption region between two strong lines in the oxygen A band is described. The theory of integrated vertical path, differential ranging, and horizontal-path pressure measurements is given, with methods to desensitize and correct for temperature effects. The properties of absorption troughs are described and shown to reduce errors due to laser frequency jitter by up to two orders of magnitude. A general analysis, including laser bandwidth effects, demonstrates that pressure measurements with an integrated-vertical-path technique are typically fifty times more accurate than with a differential ranging technique. Simulations show 0.1-0.3 percent accuracy for ground and Shuttle-based pressure-profile and surface-pressure experiments.

  13. Downhole steam generator using low pressure fuel and air supply

    DOEpatents

    Fox, Ronald L.

    1983-01-01

    An apparatus for generation of steam in a borehole for penetration into an earth formation wherein a spiral, tubular heat exchanger is used in the combustion chamber to isolate the combustion process from the water being superheated for conversion into steam. The isolation allows combustion of a relatively low pressure oxidant and fuel mixture for generating high enthalpy steam. The fuel is preheated by feedback of combustion gases from the top of the combustion chamber through a fuel preheater chamber. The hot exhaust gases of combustion at the bottom of the combustion chamber, after flowing over the heat exchanger enter an exhaust passage and pipe. The exhaust pipe is mounted inside the water supply line heating the water flowing into the heat exchanger. After being superheated in the heat exchanger, the water is ejected through an expansion nozzle and converts into steam prior to penetration into the earth formation. Pressure responsive doors are provided at a steam outlet downstream of the nozzle and close when the steam pressure is lost due to flameout.

  14. Air bubble migration rates as a proxy for bubble pressure distribution in ice cores

    NASA Astrophysics Data System (ADS)

    Dadic, Ruzica; Schneebeli, Martin; Bertler, Nancy

    2015-04-01

    Air bubble migration can be used as a proxy to measure the pressure of individual bubbles and can help constrain the gradual close-off of gas bubbles and the resulting age distribution of gases in ice cores. The close-off depth of single bubbles can vary by tens of meters, which leads to a distribution of pressures for bubbles at a given depth. The age distribution of gases (along with gas-age-ice-age differences) decreases the resolution of the gas level reconstructions from ice cores and limits our ability to determine the phase relationship between gas and ice, and thus, the impact of rapid changes of greenhouse gases on surface temperatures. For times of rapid climate change, including the last 150 years, and abrupt climate changes further back in the past, knowledge of the age distribution of the gases trapped in air bubbles will enable us to refine estimates of atmospheric changes. When a temperature gradient is applied to gas bubbles in an ice sample, the bubbles migrate toward warmer ice. This motion is caused by sublimation from the warm wall and subsequent frost deposition on the cold wall. The migration rate depends on ice temperature and bubble pressure and is proportional to the temperature gradient. The spread in migration rates for bubbles in the same samples at given temperatures should therefore reflect the variations in bubble pressures within a sample. Air bubbles with higher pressures would have been closed off higher in the firn column and thus have had time to equilibrate with the surrounding ice pressure, while air bubbles that have been closed off recently would have pressures that are similar to todays atmospheric pressure above the firn column. For ice under pressures up to ~13-16 bar, the pressure distribution of bubbles from a single depth provides a record of the trapping function of air bubbles in the firn column for a certain time in the past. We will present laboratory experiments on air bubble migration, using Antarctic ice core

  15. Ozone generation using atmospheric pressure glow discharge in air

    NASA Astrophysics Data System (ADS)

    Buntat, Z.; Smith, I. R.; Razali, N. A. M.

    2009-12-01

    This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh-1 and confirms its potential as an important ozone generation technology.

  16. The investigation of parachute fabric permeability under an unsteady pressure differential

    NASA Astrophysics Data System (ADS)

    Rondeau, Nichole C.

    An apparatus for assessing permeability of textiles subjected to time-varying pressure differentials is presented. A Computer Numerically Controlled Piston Permeability Apparatus (CNC-PPA) that can control the volume flow rate through a fabric has been designed and built. This test device has been developed in an effort to improve the understanding and design choices for aerodynamic decelerators. Preliminary results for a low permeability fabric (PIA-C-44378, Type IV) under both steady and unsteady loads are presented. The results from this investigation do indicate a small effect of unsteady pressure differential on the fabric permeability. The fabric permeability is slightly higher than the static permeability when the pressure differential is increasing with respect to time and the opposite is true when the pressure differential is decreasing. This change in permeability is more pronounced as the pressure is higher and the pressure changes more rapidly with respect to time, suggesting dynamic permeability likely affects highly unsteady phenomena such as parachute opening.

  17. The discharge of fine silica sand in a silo under different ambient air pressures

    NASA Astrophysics Data System (ADS)

    Hsiau, Shu-San; Liao, Chun-Chung; Lee, Jie-Hsien

    2012-04-01

    Silos are widely used for the industrial scale handling and transportation of powdered and granular materials. The process of discharging powder in a silo involves the flow of both solid particles and an interstitial fluid, usually air. In this study, we experimentally investigate the effects of particle size and ambient pressure on the discharge process in open- and closed-top silos. The discharge rate, pressure drop, and pressure recovery rate are measured and discussed. The results show that the particle size, the diameter of the orifice, and the ambient pressure significantly influence the process of discharge. The effect of air flow is stronger on fine-powdered flow in a closed-top silo. The results indicate that the effects of air flow could be reduced by lowering the ambient pressure. In addition, a normalized critical pressure can be defined beyond which the discharge rate increases dramatically. With reduced ambient pressure, this normalized critical pressure decreases with increasing particle size. Finally, the experimental results are compared with results calculated using the Beverloo equation and Darcy's law.

  18. Atmospheric-pressure plasma-irradiation inhibits mouse embryonic stem cell differentiation to mesoderm and endoderm but promotes ectoderm differentiation

    NASA Astrophysics Data System (ADS)

    Miura, Taichi; Hamaguchi, Satoshi; Nishihara, Shoko

    2016-04-01

    Recently, various effects of low-temperature atmospheric-pressure plasma irradiation on living cells have been demonstrated, such as tissue sterilization, blood coagulation, angiogenesis, wound healing, and tumor elimination. However, the effect of plasma-irradiation on the differentiation of mouse embryonic stem cells (mESCs) has not yet been clarified. A large number of reactive species are generated by plasma-irradiation in medium, of which hydrogen peroxide (H2O2) is one of the main species generated. Here, we investigated the effect of plasma-irradiation on the differentiation of mESCs using an embryoid body (EB) formation assay with plasma-irradiated medium or H2O2-supplemented non-irradiated medium. Our findings demonstrated that plasma-irradiated medium potently inhibits the differentiation from mESCs to mesoderm and endoderm by inhibiting Wnt signaling as determined by quantitative polymerase chain reaction and immunoblotting analyses. In contrast, both the plasma-irradiated medium and H2O2-supplemented non-irradiated medium enhanced the differentiation to epiblastoid, ectodermal, and neuronal lineages by activation of fibroblast growth factor 4 (FGF4) signaling, suggesting that these effects are caused by the H2O2 generated by plasma-irradiation in medium. However, in each case, the differentiation to glial cells remained unaffected. This study is the first demonstration that plasma-irradiation affects the differentiation of mESCs by the regulation of Wnt and FGF4 signaling pathways.

  19. Torricelli and the ocean of air: the first measurement of barometric pressure.

    PubMed

    West, John B

    2013-03-01

    The recognition of barometric pressure was a critical step in the development of environmental physiology. In 1644, Evangelista Torricelli described the first mercury barometer in a remarkable letter that contained the phrase, "We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight." This extraordinary insight seems to have come right out of the blue. Less than 10 years before, the great Galileo had given an erroneous explanation for the related problem of pumping water from a deep well. Previously, Gasparo Berti had filled a very long lead vertical tube with water and showed that a vacuum formed at the top. However, Torricelli was the first to make a mercury barometer and understand that the mercury was supported by the pressure of the air. Aristotle stated that the air has weight, although this was controversial for some time. Galileo described a method of measuring the weight of the air in detail, but for reasons that are not clear his result was in error by a factor of about two. Torricelli surmised that the pressure of the air might be less on mountains, but the first demonstration of this was by Blaise Pascal. The first air pump was built by Otto von Guericke, and this influenced Robert Boyle to carry out his classical experiments of the physiological effects of reduced barometric pressure. These were turning points in the early history of high-altitude physiology.

  20. Torricelli and the ocean of air: the first measurement of barometric pressure.

    PubMed

    West, John B

    2013-03-01

    The recognition of barometric pressure was a critical step in the development of environmental physiology. In 1644, Evangelista Torricelli described the first mercury barometer in a remarkable letter that contained the phrase, "We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight." This extraordinary insight seems to have come right out of the blue. Less than 10 years before, the great Galileo had given an erroneous explanation for the related problem of pumping water from a deep well. Previously, Gasparo Berti had filled a very long lead vertical tube with water and showed that a vacuum formed at the top. However, Torricelli was the first to make a mercury barometer and understand that the mercury was supported by the pressure of the air. Aristotle stated that the air has weight, although this was controversial for some time. Galileo described a method of measuring the weight of the air in detail, but for reasons that are not clear his result was in error by a factor of about two. Torricelli surmised that the pressure of the air might be less on mountains, but the first demonstration of this was by Blaise Pascal. The first air pump was built by Otto von Guericke, and this influenced Robert Boyle to carry out his classical experiments of the physiological effects of reduced barometric pressure. These were turning points in the early history of high-altitude physiology. PMID:23455767

  1. Torricelli and the Ocean of Air: The First Measurement of Barometric Pressure

    PubMed Central

    2013-01-01

    The recognition of barometric pressure was a critical step in the development of environmental physiology. In 1644, Evangelista Torricelli described the first mercury barometer in a remarkable letter that contained the phrase, “We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight.” This extraordinary insight seems to have come right out of the blue. Less than 10 years before, the great Galileo had given an erroneous explanation for the related problem of pumping water from a deep well. Previously, Gasparo Berti had filled a very long lead vertical tube with water and showed that a vacuum formed at the top. However, Torricelli was the first to make a mercury barometer and understand that the mercury was supported by the pressure of the air. Aristotle stated that the air has weight, although this was controversial for some time. Galileo described a method of measuring the weight of the air in detail, but for reasons that are not clear his result was in error by a factor of about two. Torricelli surmised that the pressure of the air might be less on mountains, but the first demonstration of this was by Blaise Pascal. The first air pump was built by Otto von Guericke, and this influenced Robert Boyle to carry out his classical experiments of the physiological effects of reduced barometric pressure. These were turning points in the early history of high-altitude physiology. PMID:23455767

  2. Soot formation and temperature field structure in laminar propane-air diffusion flames at elevated pressures

    SciTech Connect

    Bento, Decio S.; Guelder, OEmer L.; Thomson, Kevin A.

    2006-06-15

    The effect of pressure on soot formation and the structure of the temperature field was studied in coflow propane-air laminar diffusion flames over the pressure range of 0.1 to 0.73 MPa in a high-pressure combustion chamber. The fuel flow rate was selected so that the soot was completely oxidized within the visible flame and the flame was stable at all pressures. Spectral soot emission was used to measure radially resolved soot volume fraction and soot temperature as a function of pressure. Additional soot volume fraction measurements were made at selected heights using line-of-sight light attenuation. Soot concentration values from these two techniques agreed to within 30% and both methods exhibited similar trends in the spatial distribution of soot concentration. Maximum line-of-sight soot concentration along the flame centerline scaled with pressure; the pressure exponent was about 1.4 for pressures between 0.2 and 0.73 MPa. Peak carbon conversion to soot, defined as the percentage of fuel carbon content converted to soot, also followed a power-law dependence on pressure, where the pressure exponent was near to unity for pressures between 0.2 and 0.73 MPa. Soot temperature measurements indicated that the overall temperatures decreased with increasing pressure; however, the temperature gradients increased with increasing pressure. (author)

  3. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

    PubMed Central

    Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures. PMID:27610377

  4. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

    PubMed Central

    Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures.

  5. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor.

    PubMed

    Grossöhmichen, Martin; Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures.

  6. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor.

    PubMed

    Grossöhmichen, Martin; Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures. PMID:27610377

  7. Thermodynamic and Transport Properties of Real Air Plasma in Wide Range of Temperature and Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Chunlin; Wu, Yi; Chen, Zhexin; Yang, Fei; Feng, Ying; Rong, Mingzhe; Zhang, Hantian

    2016-07-01

    Air plasma has been widely applied in industrial manufacture. In this paper, both dry and humid air plasmas' thermodynamic and transport properties are calculated in temperature 300-100000 K and pressure 0.1-100 atm. To build a more precise model of real air plasma, over 70 species are considered for composition. Two different methods, the Gibbs free energy minimization method and the mass action law method, are used to determinate the composition of the air plasma in a different temperature range. For the transport coefficients, the simplified Chapman-Enskog method developed by Devoto has been applied using the most recent collision integrals. It is found that the presence of CO2 has almost no effect on the properties of air plasma. The influence of H2O can be ignored except in low pressure air plasma, in which the saturated vapor pressure is relatively high. The results will serve as credible inputs for computational simulation of air plasma. supported by the National Key Basic Research Program of China (973 Program)(No. 2015CB251002), National Natural Science Foundation of China (Nos. 51521065, 51577145), the Science and Technology Project Funds of the Grid State Corporation (SGTYHT/13-JS-177), the Fundamental Research Funds for the Central Universities, and State Grid Corporation Project (GY71-14-004)

  8. Air-braked cycle ergometers: validity of the correction factor for barometric pressure.

    PubMed

    Finn, J P; Maxwell, B F; Withers, R T

    2000-10-01

    Barometric pressure exerts by far the greatest influence of the three environmental factors (barometric pressure, temperature and humidity) on power outputs from air-braked ergometers. The barometric pressure correction factor for power outputs from air-braked ergometers is in widespread use but apparently has never been empirically validated. Our experiment validated this correction factor by calibrating two air-braked cycle ergometers in a hypobaric chamber using a dynamic calibration rig. The results showed that if the power output correction for changes in air resistance at barometric pressures corresponding to altitudes of 38, 600, 1,200 and 1,800 m above mean sea level were applied, then the coefficients of variation were 0.8-1.9% over the range of 160-1,597 W. The overall mean error was 3.0 % but this included up to 0.73 % for the propagated error that was associated with errors in the measurement of: a) temperature b) relative humidity c) barometric pressure d) force, distance and angular velocity by the dynamic calibration rig. The overall mean error therefore approximated the +/- 2.0% of true load that was specified by the Laboratory Standards Assistance Scheme of the Australian Sports Commission. The validity of the correction factor for barometric pressure on power output was therefore demonstrated over the altitude range of 38-1,800 m.

  9. Tables for pressure of air on coming to rest from various speeds

    NASA Technical Reports Server (NTRS)

    Zahm, A F; Louden, F A

    1930-01-01

    In Technical Report no. 247 of the National Advisory Committee for Aeronautics theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. In that report, the table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per-second, knots per hour, kilometers per hour, and meters per second. The pressure values in table II are also more exact than values given in the previous table. To furnish the aeronautical engineer with ready numerical formulas for finding the pressure of air on coming to rest, table I has been derived for the standard values specified below it. This table first presents the theoretical pressure-speed formulas and their working forms in C. G. S. Units as given in NACA Technical Report No. 247, then furnishes additional working formulas for several special units of speed. (author)

  10. Air-braked cycle ergometers: validity of the correction factor for barometric pressure.

    PubMed

    Finn, J P; Maxwell, B F; Withers, R T

    2000-10-01

    Barometric pressure exerts by far the greatest influence of the three environmental factors (barometric pressure, temperature and humidity) on power outputs from air-braked ergometers. The barometric pressure correction factor for power outputs from air-braked ergometers is in widespread use but apparently has never been empirically validated. Our experiment validated this correction factor by calibrating two air-braked cycle ergometers in a hypobaric chamber using a dynamic calibration rig. The results showed that if the power output correction for changes in air resistance at barometric pressures corresponding to altitudes of 38, 600, 1,200 and 1,800 m above mean sea level were applied, then the coefficients of variation were 0.8-1.9% over the range of 160-1,597 W. The overall mean error was 3.0 % but this included up to 0.73 % for the propagated error that was associated with errors in the measurement of: a) temperature b) relative humidity c) barometric pressure d) force, distance and angular velocity by the dynamic calibration rig. The overall mean error therefore approximated the +/- 2.0% of true load that was specified by the Laboratory Standards Assistance Scheme of the Australian Sports Commission. The validity of the correction factor for barometric pressure on power output was therefore demonstrated over the altitude range of 38-1,800 m. PMID:11071051

  11. A barometric pressure sensor based on the air-gap scale effect in a cantilever

    NASA Astrophysics Data System (ADS)

    Minh-Dung, Nguyen; Takahashi, Hidetoshi; Uchiyama, Takeshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2013-09-01

    The most common structure for a conventional barometric pressure sensor consists of a vacuum-sealed cavity and a diaphragm. However, we hypothesize that a simple structure with an unsealed cavity and an ultra-thin cantilever can provide more sensitive measurements. We produced a 300-nm-thick cantilever with a small spring constant, which made the cantilever sensitive to low pressures. We demonstrated that miniaturizing the air-gap of the cantilever enables the sensor to measure barometric pressure changes at a low pressure change rate with a high resolution, which was 1 Pa at 0.05 Hz, and for a gap size of 1.7 μm.

  12. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    NASA Astrophysics Data System (ADS)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui; Zhang, Jue; Fang, Jing

    2015-10-01

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  13. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    SciTech Connect

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui; Zhang, Jue Fang, Jing

    2015-10-15

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  14. Differential control of systolic and diastolic blood pressure in blacks with essential hypertension.

    PubMed Central

    Ayodele, Olugbenga E.; Alebiosu, C. Olutayo; Salako, Babatunde L.

    2004-01-01

    OBJECTIVE: The risk of cardiovascular and renal diseases has been shown to be higher for systolic blood pressure than diastolic blood pressure. The aim of this study was to assess the differential control of systolic and diastolic blood pressure in Nigerians with primary hypertension. DESIGN AND SETTING: This was a prospective observational study carried out at the Medical Outpatient Department of the State Hospital, Abeokuta, Nigeria. Ethical approval for the study was obtained from the ethical committee of the hospital. METHODOLOGY: The study population consisted of 185 consecutive patients (65 males, 120 females), aged 35-85 years with primary hypertension who had been on drugs one- to 25 years prior to the onset of the study. Clinic blood pressure control was assessed during a year period. Six consecutive clinic blood pressure readings were recorded for each patient and the average calculated (systolic blood pressure and diastolic blood pressure separately). Patients were classified into subgroups based on the pattern of blood pressure control. RESULTS: Clinic systolic blood pressure and diastolic blood pressure was controlled in 58 patients (31.4%). Systolic blood pressure control was less frequent than diastolic blood pressure control (35.7% versus 51.4%, p<0.05). Patients with uncontrolled systolic blood pressure were significantly older than patients with only uncontrolled diastolic blood pressure (66.7+/-7.4 versus 52.9+/-8.7 years, p<0.001). CONCLUSION: Systolic blood pressure is less frequently controlled than diastolic blood pressure in Nigerians treated for primary hypertension. This may increase the patient's risk of developing stroke, and cardiovascular and renal complications. PMID:15040512

  15. A Lateral Differential Resonant Pressure Microsensor Based on SOI-Glass Wafer-Level Vacuum Packaging.

    PubMed

    Xie, Bo; Xing, Yonghao; Wang, Yanshuang; Chen, Jian; Chen, Deyong; Wang, Junbo

    2015-09-21

    This paper presents the fabrication and characterization of a resonant pressure microsensor based on SOI-glass wafer-level vacuum packaging. The SOI-based pressure microsensor consists of a pressure-sensitive diaphragm at the handle layer and two lateral resonators (electrostatic excitation and capacitive detection) on the device layer as a differential setup. The resonators were vacuum packaged with a glass cap using anodic bonding and the wire interconnection was realized using a mask-free electrochemical etching approach by selectively patterning an Au film on highly topographic surfaces. The fabricated resonant pressure microsensor with dual resonators was characterized in a systematic manner, producing a quality factor higher than 10,000 (~6 months), a sensitivity of about 166 Hz/kPa and a reduced nonlinear error of 0.033% F.S. Based on the differential output, the sensitivity was increased to two times and the temperature-caused frequency drift was decreased to 25%.

  16. A Lateral Differential Resonant Pressure Microsensor Based on SOI-Glass Wafer-Level Vacuum Packaging

    PubMed Central

    Xie, Bo; Xing, Yonghao; Wang, Yanshuang; Chen, Jian; Chen, Deyong; Wang, Junbo

    2015-01-01

    This paper presents the fabrication and characterization of a resonant pressure microsensor based on SOI-glass wafer-level vacuum packaging. The SOI-based pressure microsensor consists of a pressure-sensitive diaphragm at the handle layer and two lateral resonators (electrostatic excitation and capacitive detection) on the device layer as a differential setup. The resonators were vacuum packaged with a glass cap using anodic bonding and the wire interconnection was realized using a mask-free electrochemical etching approach by selectively patterning an Au film on highly topographic surfaces. The fabricated resonant pressure microsensor with dual resonators was characterized in a systematic manner, producing a quality factor higher than 10,000 (~6 months), a sensitivity of about 166 Hz/kPa and a reduced nonlinear error of 0.033% F.S. Based on the differential output, the sensitivity was increased to two times and the temperature-caused frequency drift was decreased to 25%. PMID:26402679

  17. Negative pressure of the environmental air in the cleaning area of the materials and sterilization center: a systematic review

    PubMed Central

    Ciofi-Silva, Caroline Lopes; Hansen, Lisbeth Lima; Almeida, Alda Graciele Claudio dos Santos; Kawagoe, Julia Yaeko; Padoveze, Maria Clara; Graziano, Kazuko Uchikawa

    2016-01-01

    ABSTRACT Objective: to analyze the scientific evidence on aerosols generated during cleaning activities of health products in the Central Service Department (CSD) and the impact of the negative pressure of the ambient air in the cleaning area to control the dispersion of aerosols to adjacent areas. Method: for this literature systematic review the following searches were done: search guidelines, manuals or national and international technical standards given by experts; search in the portal and databases PubMed, Scopus, CINAHL and Web of Science; and a manual search of scientific articles. Results: the five technical documents reviewed recommend that the CSD cleaning area should have a negative differential ambient air pressure, but scientific articles on the impact of this intervention were not found. The four articles included talked about aerosols formed after the use of a ultrasonic cleaner (an increased in the contamination especially during use) and pressurized water jet (formation of smaller aerosols 5μm). In a study, the aerosols formed from contaminated the hot tap water with Legionella pneumophila were evaluated. Conclusions: there is evidence of aerosol formation during cleanup activities in CSD. Studies on occupational diseases of respiratory origin of workers who work in CSD should be performed. PMID:27598374

  18. Differential pressure distribution measurement with an MEMS sensor on a free-flying butterfly wing.

    PubMed

    Takahashi, Hidetoshi; Tanaka, Hiroto; Matsumoto, Kiyoshi; Shimoyama, Isao

    2012-09-01

    An insect can perform various flight maneuvers. However, the aerodynamic force generated by real insect wings during free flight has never been measured directly. In this study, we present the direct measurement of the four points of the differential pressures acting on the wing surface of a flying insect. A small-scale differential pressure sensor of 1.0 mm × 1.0 mm × 0.3 mm in size was developed using microelectromechanical systems (MEMS) and was attached to a butterfly wing. Total weight of the sensor chip and the flexible electrode on the wing was 4.5 mg, which was less than 10% of the wing weight. Four points on the wing were chosen as measurement points, and one sensor chip was attached in each flight experiment. During takeoff, the wing's flapping motion induced a periodic and symmetric differential pressure between upstroke and downstroke. The average absolute value of the local differential pressure differed significantly with the location: 7.4 Pa at the forewing tip, 5.5 Pa at the forewing center, 2.1 Pa at the forewing root and 2.1 Pa at the hindwing center. The instantaneous pressure at the forewing tip reached 10 Pa, which was ten times larger than wing loading of the butterfly.

  19. Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells

    SciTech Connect

    Zhang, Xianhui; Yang, Si-ze; Liu, Dongping; Song, Ying; Sun, Yue

    2013-05-15

    The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

  20. Race-Based Differential Prediction in Air Force Technical Training Programs.

    ERIC Educational Resources Information Center

    Houston, Walter M.; Novick, Melvin R.

    1987-01-01

    Bayesian Johnson-Neyman methodology was used to investigate differential prediction by race in U.S. Air Force training programs. Meaningful differences were found in eight of nine comparisons. The setting of the cutting scores had an effect on whether the bias was positive or negative for Blacks. (Author/GDC)

  1. Characterization of the respiratory and heart beat signal from an air pressure-based ballistocardiographic setup.

    PubMed

    Willemen, Tim; Van Deun, Dorien; Verhaert, Vincent; Van Huffel, Sabine; Haex, Bart; Vander Sloten, Jos

    2014-01-01

    Off-body detection of respiratory and cardiac activity presents an enormous opportunity for general health, stress and sleep quality monitoring. The presented setup detects the mechanical activity of both heart and lungs by measuring pressure difference fluctuations between two air volumes underneath the chest area of the subject. The registered signals were characterized over four different sleep postures, three different base air pressures within the air volumes and three different mattress top layer materials. Highest signal strength was detected in prone posture for both the respiratory and heart beat signal. Respiratory signal strength was the lowest in supine posture, while heart beat signal strength was lowest for right lateral. Heart beat cycle variability was highest in prone and lowest in supine posture. Increasing the base air pressure caused a reduction in signal amplitude for both the respiratory and the heart beat signal. A visco-elastic poly-urethane foam top layer had significantly higher respiration amplitude compared to high resilient poly-urethane foam and latex foam. For the heart beat signal, differences between the top layers were small. The authors conclude that, while the influence of the mattress top layer material is small, the base air pressure can be tuned for optimal mechanical transmission from heart and lungs towards the registration setup.

  2. Characteristics of radio-frequency, atmospheric-pressure glow discharges with air using bare metal electrodes

    SciTech Connect

    Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Zhang Xiaozhang

    2006-10-16

    In this letter, an induced gas discharge approach is proposed and described in detail for obtaining a uniform atmospheric-pressure glow discharge with air in a {gamma} mode using water-cooled, bare metal electrodes driven by radio-frequency (13.56 MHz) power supply. A preliminary study on the discharge characteristics of the air glow discharge is also presented in this study. With this induced gas discharge approach, radio-frequency, atmospheric-pressure glow discharges using bare metal electrodes with other gases which cannot be ignited directly as the plasma working gas, such as nitrogen, oxygen, etc., can also be obtained.

  3. GSOD Based Daily Global Mean Surface Temperature and Mean Sea Level Air Pressure (1982-2011)

    DOE Data Explorer

    Xuan Shi, Dali Wang

    2014-05-05

    This data product contains all the gridded data set at 1/4 degree resolution in ASCII format. Both mean temperature and mean sea level air pressure data are available. It also contains the GSOD data (1982-2011) from NOAA site, contains station number, location, temperature and pressures (sea level and station level). The data package also contains information related to the data processing methods

  4. Simplified configuration for the combustor of an oil burner using a low pressure, high flow air-atomizing nozzle

    DOEpatents

    Butcher, Thomas A.; Celebi, Yusuf; Fisher, Leonard

    2000-09-15

    The invention relates to clean burning of fuel oil with air. More specifically, to a fuel burning combustion head using a low-pressure, high air flow atomizing nozzle so that there will be a complete combustion of oil resulting in a minimum emission of pollutants. The improved fuel burner uses a low pressure air atomizing nozzle that does not result in the use of additional compressors or the introduction of pressurized gases downstream, nor does it require a complex design. Inventors:

  5. Effects of hydraulic pressure on the performance of single chamber air-cathode microbial fuel cells.

    PubMed

    Cheng, Shaoan; Liu, Weifeng; Guo, Jian; Sun, Dan; Pan, Bin; Ye, Yaoli; Ding, Weijun; Huang, Haobin; Li, Fujian

    2014-06-15

    Scaling up of microbial fuel cells (MFCs) without losing power density requires a thorough understanding of the effect of hydraulic pressure on MFC performance. In this work, the performance of an activated carbon air-cathode MFC was evaluated under different hydraulic pressures. The MFC under 100 mmH2O hydraulic pressure produced a maximum power density of 1260 ± 24 mW m(-2), while the power density decreased by 24.4% and 44.7% as the hydraulic pressure increased to 500 mmH2O and 2000 mmH2O, respectively. Notably, the performance of both the anode and the cathode had decreased under high hydraulic pressures. Electrochemical impedance spectroscopy tests of the cathode indicated that both charge transfer resistance and diffusion transfer resistance increased with the increase in hydraulic pressure. Denaturing gradient gel electrophoresis of PCR-amplified partial 16S rRNA genes demonstrated that the similarity among anodic biofilm communities under different hydraulic pressures was ≥ 90%, and the communities of all MFCs were dominated by Geobacter sp. These results suggested that the reduction in power output of the single chamber air-cathode MFC under high hydraulic pressures can be attributed to water flooding of the cathode and suppression the metabolism of anodic exoelectrogenic bacteria.

  6. An analysis of contact stiffness between a finger and an object when wearing an air-cushioned glove: the effects of the air pressure.

    PubMed

    Wu, John Z; Wimer, Bryan M; Welcome, Daniel E; Dong, Ren G

    2012-04-01

    Air-cushioned gloves have the advantages of lighter weight, lower cost, and unique mechanical performance, compared to gloves made of conventional engineering materials. The goal of this study is to analyze the contact interaction between fingers and object when wearing an air-cushioned glove. The contact interactions between the the fingertip and air bubbles, which is considered as a cell of a typical air-cushioned glove, has been analyzed theoretically. Two-dimensional finite element models were developed for the analysis. The fingertip model was assumed to be composed of skin layers, subcutaneous tissue, bone, and nail. The air bubbles were modeled as air sealed in the container of nonelastic membrane. We simulated two common scenarios: a fingertip in contact with one single air bubble and with two air cushion bubbles simultaneously. Our simulation results indicated that the internal air pressure can modulate the fingertip-object contact characteristics. The contact stiffness reaches a minimum when the initial air pressure is equal to 1.3 and 1.05 times of the atmosphere pressure for the single air bubble and the double air bubble contact, respectively. Furthermore, the simulation results indicate that the double air bubble contact will result in smaller volumetric tissue strain than the single air bubble contact for the same force.

  7. Pressure-loss and flow coefficients inside a chordwise-finned, impingement, convection, and film air-cooled turbine vane

    NASA Technical Reports Server (NTRS)

    Hippensteele, S. A.

    1974-01-01

    Total-pressure-loss coefficients, flow discharge coefficients, and friction factors were determined experimentally for the various area and geometry changes and flow passages within an air-cooled turbine vane. The results are compared with those of others obtained on similar configurations, both actual and large models, of vane passages. The supply and exit air pressures were controlled and varied. The investigation was conducted with essentially ambient-temperature air and without external flow of air over the vane.

  8. Effect of pressure on structure and NO sub X formation in CO-air diffusion flames

    NASA Technical Reports Server (NTRS)

    Maahs, H. G.; Miller, I. M.

    1979-01-01

    A study was made of nitric oxide formation in a laminar CO-air diffusion flame over a pressure range from 1 to 50 atm. The carbon monoxide (CO) issued from a 3.06 mm diameter port coaxially into a coflowing stream of air confined within a 20.5 mm diameter chimney. Nitric oxide concentrations from the flame were measured at two carbon monoxide (fuel) flow rates: 73 standard cubic/min and 146 sccm. Comparison of the present data with data in the literature for a methane-air diffusion flame shows that for flames of comparable flame height (8 to 10 mm) and pseudoequivalence ratio (0.162), the molar emission index of a CO-air flame is significantly greater than that of a methane-air flame.

  9. High pressure ceramic air heater for indirectly fired gas turbine applications

    SciTech Connect

    LaHaye, P.G.; Briggs, G.F.; Orozxo, N.J.; Seger, J.L.

    1993-11-01

    The EFCC cycle is conceptually simple. Air enters the compressor where it is pressurized and becomes the tube-side flow of the ceramic air heater. Heat transferred from the hot combustion gases flowing through the shell-side raises the air temperature to the desired turbine inlet temperature. Internally insulated high pressure piping returns the heated compressor air to the turbine, where it is expanded providing power to drive the electric generator and gas turbine compressor. Exhaust air from the turbine is used as the combustion air for the coal combustor. The EFCC cycle burns pulverized coal in an atmospheric combustion chamber similar to the combustion system in a conventional steam generator. The combustion gas exits the combustor and enters a slag screen, or impact separator, where the larger ash particles are collected to prevent fouling of the heat exchanger. After the slag screen, the combustion gas enters the shell-side of the CerHX where its thermal energy is transferred to the tube side air flow. Shell-side exit temperatures are sufficiently high to provide thermal energy for the bottoming Rankine Cycle through a heat recovery steam generator. Exhaust gas exiting the steam generator passes through a flue gas desulfurization system and a particulate removal system.

  10. Engineering Task Plan for Hepa Filter Differential Pressure (DP) Fan Interlock Upgrades

    SciTech Connect

    SIMONS, S.R.

    2000-05-19

    This document provides a plan for installation of Differential Pressure (DP) fan interlocks on the primary ventilation systems in selected Tank Farm facilities. This plan contains the engineering tasks required for installation and is summarized by the Acceptance for Beneficial Use list. Individuals responsible for each task are identified and scheduled accordingly.

  11. Software Verification and Validation Test Report for the HEPA filter Differential Pressure Fan Interlock System

    SciTech Connect

    ERMI, A.M.

    2000-09-05

    The HEPA Filter Differential Pressure Fan Interlock System PLC ladder logic software was tested using a Software Verification and Validation (V&V) Test Plan as required by the ''Computer Software Quality Assurance Requirements''. The purpose of his document is to report on the results of the software qualification.

  12. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static pressure in the facepiece shall not exceed 38 mm. (1.5 inches) of water-column height. (b) The pressure...

  13. 49 CFR 393.51 - Warning signals, air pressure and vacuum gauges.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Warning signals, air pressure and vacuum gauges... and vacuum gauges. (a) General Rule. Every bus, truck and truck tractor, except as provided in.... (d) Vacuum brakes. A commercial motor vehicle (regardless of the date it was manufactured)...

  14. 49 CFR 393.51 - Warning signals, air pressure and vacuum gauges.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Warning signals, air pressure and vacuum gauges... and vacuum gauges. (a) General Rule. Every bus, truck and truck tractor, except as provided in.... (d) Vacuum brakes. A commercial motor vehicle (regardless of the date it was manufactured)...

  15. 49 CFR 393.51 - Warning signals, air pressure and vacuum gauges.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Warning signals, air pressure and vacuum gauges... and vacuum gauges. (a) General Rule. Every bus, truck and truck tractor, except as provided in.... (d) Vacuum brakes. A commercial motor vehicle (regardless of the date it was manufactured)...

  16. 49 CFR 393.51 - Warning signals, air pressure and vacuum gauges.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Warning signals, air pressure and vacuum gauges... and vacuum gauges. (a) General Rule. Every bus, truck and truck tractor, except as provided in.... (d) Vacuum brakes. A commercial motor vehicle (regardless of the date it was manufactured)...

  17. 49 CFR 393.51 - Warning signals, air pressure and vacuum gauges.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Warning signals, air pressure and vacuum gauges... and vacuum gauges. (a) General Rule. Every bus, truck and truck tractor, except as provided in.... (d) Vacuum brakes. A commercial motor vehicle (regardless of the date it was manufactured)...

  18. Negative Intraoral Air Pressures of Deaf Children with Cochlear Implants: Physiology, Phonology, and Treatment.

    ERIC Educational Resources Information Center

    Higgins, Maureen B.; And Others

    1996-01-01

    A study of four children with deafness who had cochlear implants investigated the use of negative intraoral air pressure in articulation, from both the physiological and phonological perspectives. The study showed that the children used speech-production strategies that were different from hearing children and that deviant speech behaviors should…

  19. Compressed-air work is entering the field of high pressures.

    PubMed

    Le Péchon, J Cl; Gourdon, G

    2010-01-01

    Since 1850, compressed-air work has been used to prevent shafts or tunnels under construction from flooding. Until the 1980s, workers were digging in compressed-air environments. Since the introduction of tunnel boring machines (TBMs), very little digging under pressure is needed. However, the wearing out of cutter-head tools requires inspection and repair. Compressed-air workers enter the pressurized working chamber only occasionally to perform such repairs. Pressures between 3.5 and 4.5 bar, that stand outside a reasonable range for air breathing, were reached by 2002. Offshore deep diving technology had to be adapted to TBM work. Several sites have used mixed gases: in Japan for deep shaft sinking (4.8 bar), in The Netherlands at Western Scheldt Tunnels (6.9 bar), in Russia for St. Petersburg Metro (5.8 bar) and in the United States at Seattle (5.8 bar). Several tunnel projects are in progress that may involve higher pressures: Hallandsås (Sweden) interventions in heliox saturation up to 13 bar, and Lake Mead (U.S.) interventions to about 12 bar (2010). Research on TBMs and grouting technologies tries to reduce the requirements for hyperbaric works. Adapted international rules, expertise and services for saturation work, shuttles and trained personnel matching industrial requirements are the challenges. PMID:20737925

  20. SOIL-AIR PERMEABILITY MEASUREMENT WITH A TRANSIENT PRESSURE BUILDUP METHOD

    EPA Science Inventory

    An analytical solution for transient pressure change in a single venting well was derived from mass conservation of air, Darcy's law of flow in porous media, and the ideal gas law equation of state. Slopes of plots of Pw2 against ln (t+Δt)/Δt similar to Homer's plot were used to ...

  1. The Impact of a Science Demonstration on Children's Understanding of Air Pressure.

    ERIC Educational Resources Information Center

    Shepardson, Damiel P.; And Others

    1994-01-01

    Examines 52 fifth graders' written and oral responses to determine the impact of a scientific demonstration on their understanding of air pressure. For one-third of the children, the demonstration reinforced previous understanding. Recommendations for using demonstrations to promote children's scientific understanding are presented. (ZWH)

  2. The Determination of the Percent of Oxygen in Air Using a Gas Pressure Sensor

    ERIC Educational Resources Information Center

    Gordon, James; Chancey, Katherine

    2005-01-01

    The experiment of determination of the percent of oxygen in air is performed in a general chemistry laboratory in which students compare the results calculated from the pressure measurements obtained with the calculator-based systems to those obtained in a water-measurement method. This experiment allows students to explore a fundamental reaction…

  3. Promoting Students' Learning of Air Pressure Concepts: The Interrelationship of Teaching Approaches and Student Learning Characteristics

    ERIC Educational Resources Information Center

    She, Hsiao-Ching

    2005-01-01

    The author explored the potential to promote students' understanding of difficult science concepts through an examination of the inter-relationships among the teachers' instructional approach, students' learning preference styles, and their levels of learning process. The concept "air pressure," which requires an understanding of invisible,…

  4. Hydrostatic pressure effect on micro air bubbles deposited on surfaces with a retreating tip.

    PubMed

    Huynh, So Hung; Wang, Jingming; Yu, Yang; Ng, Tuck Wah

    2014-06-01

    The effect of hydrostatic pressure on 6 μL air bubbles formed on micropillar structured PDMS and silicone surfaces using a 2 mm diameter stainless steel tip retreated at 1 mm/s was investigated. Dimensional analysis of the tip retraction process showed the experiments to be conducted in the condition where fluid inertial forces are comparable in magnitude with surface tension forces, while viscous forces were lower. Larger bubbles could be left behind on the structured PDMS surface. For hydrostatic pressures in excess of 20 mm H2O (196 Pa), the volume of bubble deposited was found to decrease progressively with pressure increase. The differences in width of the deposited bubbles (in contact with the substrate) were significant at any particular pressure but marginal in height. The attainable height before rupture reduced with pressure increase, thereby accounting for the reducing dispensed volume characteristic. On structured PDMS, the gaseous bridge width (in contact with the substrate) was invariant with tip retraction, while on silicone it was initially reducing before becoming invariant in the lead up to rupture. With silicone, hence, reductions in the contact width and height were both responsible for reduced volumes with pressure increase. Increased hydrostatic pressure was also found to restrict the growth in contact width on silicone during the stage when air was injected in through the tip. The ability to effect bubble size in such a simple manner may already be harnessed in nature and suggests possibilities in technological applications.

  5. Acute Effects of Continuous Positive Air way Pressure on Pulse Pressure in Chronic Heart Failure

    PubMed Central

    Quintão, Mônica; Chermont, Sérgio; Marchese, Luana; Brandão, Lúcia; Bernardez, Sabrina Pereira; Mesquita, Evandro Tinoco; Rocha, Nazareth de Novaes; Nóbrega, Antônio Claudio L.

    2014-01-01

    Background Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP. Objective The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF. Methods Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60 ± 11 years; BMI 29 ± 5 kg/cm2, NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH2O, whereas placebo was fixed at 0-1 cmH2O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode. Results CPAP decreased resting heart rate (Pre: 72 ± 9; vs. Post 5 min: 67 ± 10 bpm; p < 0.01) and MAP (CPAP: 87 ± 11; vs. control 96 ± 11 mmHg; p < 0.05 post 5 min). CPAP decreased PP (CPAP: 47 ± 20 pre to 38 ± 19 mmHg post; vs. control: 42 ± 12 mmHg, pre to 41 ± 18 post p < 0.05 post 5 min). Conclusion NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome. PMID:24676373

  6. Near-complete optic nerve transection by high-pressure air

    PubMed Central

    Ko, Soo Won; Lee, Jong Seok; Choi, Han Sung; Ko, Young Gwan; Hong, Hoon Pyo

    2016-01-01

    The use of high-pressure air instruments has become more common. Consequently, there have been a number of cases of orbital emphysema caused by contact with high-pressure air. In this case, a 62-year-old male patient visited an emergency medical center after his left eye was shot by an air compressor gun that was used to wash cars. Lacerations were observed in the upper and lower eyelids of his left eye. Radiological examinations revealed orbital emphysema, optic nerve transection, pneumocephalus, and subcutaneous emphysema in the face, neck, shoulder, and mediastinum. Canalicular injury repair was performed, and the emphysema resolved. However, there was near-complete vision loss in the patient’s left eye. Because most optic nerve transections occur after a severe disruption in bone structure, pure optic nerve transections without any injury of the bone structure, as in the present case, is extremely rare. PMID:27752640

  7. An investigation of air solubility in Jet A fuel at high pressures

    NASA Technical Reports Server (NTRS)

    Faeth, G. M.

    1981-01-01

    Problems concerned with the supercritical injection concept are discussed. Supercritical injection involves dissolving air into a fuel prior to injection. A similar effect is obtained by preheating the fuel so that a portion of the fuel flashes when its pressure is reduced. Flashing improves atomization properties and the presence of air in the primary zone of a spray flame reduces the formation of pollutants. The investigation is divided into three phases: (1) measure the solubility and density properties of fuel/gas mixtures, including Jet A/air, at pressures and correlate these results using theory; (2) investigate the atomization properties of flashing liquids, including fuel/dissolved gas systems. Determine and correlate the effect of inlet properties and injector geometry on mass flow rates, Sauter mean diameter and spray angles; (3) examine the combustion properties of flashing injection in an open burner flame, considering flame shape and soot production.

  8. Acute changes in pulse pressure in relation to constituents of particulate air pollution in elderly persons

    SciTech Connect

    Jacobs, Lotte; Buczynska, Anna; Walgraeve, Christophe; Delcloo, Andy; Potgieter-Vermaak, Sanja; Van Grieken, Rene; Demeestere, Kristof; Dewulf, Jo; Van Langenhove, Herman; De Backer, Hugo; Nemery, Benoit; Nawrot, Tim S.

    2012-08-15

    An increased pulse pressure (difference between systolic and diastolic blood pressure) suggests aortic stiffening. The objective of this study was to examine the acute effects of both particulate matter (PM) mass and composition on blood pressure, among elderly persons. We carried out a panel study in persons living in elderly homes in Antwerp, Belgium. We recruited 88 non-smoking persons, 70% women with a mean age of 83 years (standard deviation: 5.2). Blood pressure was measured and a blood sample was collected on two time points, which were chosen so that there was an exposure contrast in ambient PM exposure. The elemental content of the collected indoor and outdoor PM{sub 2.5} (particulate matter with an aerodynamic diameter <2.5 {mu}m) mass concentration was measured. Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) on outdoor PM{sub 10} (particulate matter with an aerodynamic diameter <10 {mu}m) were measured. Each interquartile range increase of 20.8 {mu}g/m Superscript-Three in 24-h mean outdoor PM{sub 2.5} was associated with an increase in pulse pressure of 4.0 mmHg (95% confidence interval: 1.8-6.2), in persons taking antihypertensive medication (n=57), but not in persons not using antihypertensive medication (n=31) (p for interaction: 0.02). Vanadium, iron and nickel contents of PM{sub 2.5} were significantly associated with systolic blood pressure and pulse pressure, among persons on antihypertensive medication. Similar results were found for indoor concentrations. Of the oxy-PAHs, chrysene-5,6-dione and benzo[a]pyrene-3,6-dione were significantly associated with increases in systolic blood pressure and pulse pressure. In elderly, pulse pressure was positively associated with acute increases in outdoor and indoor air pollution, among persons taking antihypertensive medication. These results might form a mechanistic pathway linking air pollution as a trigger of cardiovascular events.

  9. On Static Pressure Fluctuation between Sirocco Fan Blades in a Car Air-Conditioning System

    NASA Astrophysics Data System (ADS)

    Sakai, Yasuhiko; Kato, Takaaki; Moriguchi, Yuu; Sakai, Masaharu; Ito, Kouji; Mitsuishi, Yasushi; Nagata, Kouji; Kubo, Takashi

    In this study, special attention is directed to static pressure fluctuation in a sirocco fan for a car air-conditioning system, because it is expected that there is a close connection between the fluid noise and the pressure fluctuation. The final purpose of this study is to clarify the relationship between the static pressure fluctuation between fan blades and the sound noise emitted to the outside of the fan, and to develop an air-conditioning system with highly low noise level. For this purpose, first of all, a new micro probe for the measurement of static pressure fluctuation has been developed. This new micro probe is composed of an L-type static pressure tube (the outer diameter is 0.5 mm and the inner diameter is 0.34 mm) and a very small pressure transducer. This probe exhibits a flat frequency response until approximately 2,000 Hz, and it is set between the blades of the fan rotating at 1,500 rpm. The measurements of the static pressure fluctuation between the blades have been performed, and the intensity of sound source was quantified from the second derivative of the phase-averaged static pressure fluctuation signals on the basis of Ribner's formula (Ribner 1962). The experiments have been made in two different modes, i.e., the cooling mode (FACE MODE) and the heating mode (FOOT MODE). It is shown that the static pressure increases rapidly as the blade approaches to the nose of the casing. It is also found that the sound source for FACE MODE shows the larger value than that for FOOT MODE as a whole. In particular, the largest intensity of sound source is observed when the blade approaches to the nose. From these results, it is confirmed that the present new static pressure probe is useful to specify the distributions of sound source in a sirocco fan.

  10. Acute changes in pulse pressure in relation to constituents of particulate air pollution in elderly persons.

    PubMed

    Jacobs, Lotte; Buczynska, Anna; Walgraeve, Christophe; Delcloo, Andy; Potgieter-Vermaak, Sanja; Van Grieken, René; Demeestere, Kristof; Dewulf, Jo; Van Langenhove, Herman; De Backer, Hugo; Nemery, Benoit; Nawrot, Tim S

    2012-08-01

    An increased pulse pressure (difference between systolic and diastolic blood pressure) suggests aortic stiffening. The objective of this study was to examine the acute effects of both particulate matter (PM) mass and composition on blood pressure, among elderly persons. We carried out a panel study in persons living in elderly homes in Antwerp, Belgium. We recruited 88 non-smoking persons, 70% women with a mean age of 83 years (standard deviation: 5.2). Blood pressure was measured and a blood sample was collected on two time points, which were chosen so that there was an exposure contrast in ambient PM exposure. The elemental content of the collected indoor and outdoor PM(2.5) (particulate matter with an aerodynamic diameter <2.5 μm) mass concentration was measured. Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) on outdoor PM(10) (particulate matter with an aerodynamic diameter <10 μm) were measured. Each interquartile range increase of 20.8 μg/m³ in 24-h mean outdoor PM(2.5) was associated with an increase in pulse pressure of 4.0 mm Hg (95% confidence interval: 1.8-6.2), in persons taking antihypertensive medication (n=57), but not in persons not using antihypertensive medication (n=31) (p for interaction: 0.02). Vanadium, iron and nickel contents of PM(2.5) were significantly associated with systolic blood pressure and pulse pressure, among persons on antihypertensive medication. Similar results were found for indoor concentrations. Of the oxy-PAHs, chrysene-5,6-dione and benzo[a]pyrene-3,6-dione were significantly associated with increases in systolic blood pressure and pulse pressure. In elderly, pulse pressure was positively associated with acute increases in outdoor and indoor air pollution, among persons taking antihypertensive medication. These results might form a mechanistic pathway linking air pollution as a trigger of cardiovascular events.

  11. Method and system for measuring multiphase flow using multiple pressure differentials

    DOEpatents

    Fincke, James R.

    2001-01-01

    An improved method and system for measuring a multiphase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multiphase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The method for determining the mass flow of the high void fraction fluid flow and the gas flow includes certain steps. The first step is calculating a gas density for the gas flow. The next two steps are finding a normalized gas mass flow rate through the venturi and computing a gas mass flow rate. The following step is estimating the gas velocity in the venturi tube throat. The next step is calculating the pressure drop experienced by the gas-phase due to work performed by the gas phase in accelerating the liquid phase between the upstream pressure measuring point and the pressure measuring point in the venturi throat. Another step is estimating the liquid velocity in the venturi throat using the calculated pressure drop experienced by the gas-phase due to work performed by the gas phase. Then the friction is computed between the liquid phase and a wall in the venturi tube. Finally, the total mass flow rate based on measured pressure in the venturi throat is calculated, and the mass flow rate of the liquid phase is calculated from the difference of the total mass flow rate and the gas mass flow rate.

  12. Investigation of the reaction of liquid hydrogen with liquid air in a pressure tube

    NASA Technical Reports Server (NTRS)

    Karb, Erich H.

    1987-01-01

    A pressure tube should protect the FR-2 reactor from the consequences of a hydrogen-air reaction, which is conceivable in the breakdown of several safety devices of the planned cold neutron source Project FR-2/16. The magnitudes and time pattern of the pressures to be expected were investigated. In the geometry used and the ignition mechanism selected, which is comparable to the strongest ignition process conceivable in the reactor, the reaction proceeds with greater probability than combustion. The combustion is possibly smaller if local limited partial detonations are superimposed. The magnitude of the pressure was determined by the masses of the reaction partners, liquid H2 and liquid air, and determines their ratio to each other.

  13. Layers of air in the water beneath the floating fern Salvinia are exposed to fluctuations in pressure.

    PubMed

    Mayser, Matthias J; Barthlott, Wilhelm

    2014-12-01

    Superhydrophobic, hierarchically structured, technical surfaces (Lotus-effect) are of high scientific and economic interest because of their remarkable properties. Recently, the immense potential of air-retaining superhydrophobic surfaces, for example, for low-friction transport of fluids and drag-reducing coatings of ships has begun to be explored. A major problem of superhydrophobic surfaces mimicking the Lotus-effect is the limited persistence of the air retained, especially under rough conditions of flow. However, there are a variety of floating or diving plant and animal species that possess air-retaining surfaces optimized for durable water-repellency (Salvinia-effect). Especially floating ferns of the genus Salvinia have evolved superhydrophobic surfaces capable of maintaining layers of air for months. Apart from maintaining stability under water, the layer of air has to withstand the stresses of water pressure (up to 2.5 bars). Both of these aspects have an application to create permanent air layers on ships' hulls. We investigated the effect of pressure on air layers in a pressure cell and exposed the air layer to pressures of up to 6 bars. We investigated the suppression of the air layer at increasing pressures as well as its restoration during decreases in pressure. Three of the four examined Salvinia species are capable of maintaining air layers at pressures relevant to the conditions applying to ships' hulls. High volumes of air per surface area are advantageous for retaining at least a partial Cassie-Baxter-state under pressure, which also helps in restoring the air layer after depressurization. Closed-loop structures such as the baskets at the top of the "egg-beater hairs" (see main text) also help return the air layer to its original level at the tip of the hairs by trapping air bubbles.

  14. Layers of air in the water beneath the floating fern Salvinia are exposed to fluctuations in pressure.

    PubMed

    Mayser, Matthias J; Barthlott, Wilhelm

    2014-12-01

    Superhydrophobic, hierarchically structured, technical surfaces (Lotus-effect) are of high scientific and economic interest because of their remarkable properties. Recently, the immense potential of air-retaining superhydrophobic surfaces, for example, for low-friction transport of fluids and drag-reducing coatings of ships has begun to be explored. A major problem of superhydrophobic surfaces mimicking the Lotus-effect is the limited persistence of the air retained, especially under rough conditions of flow. However, there are a variety of floating or diving plant and animal species that possess air-retaining surfaces optimized for durable water-repellency (Salvinia-effect). Especially floating ferns of the genus Salvinia have evolved superhydrophobic surfaces capable of maintaining layers of air for months. Apart from maintaining stability under water, the layer of air has to withstand the stresses of water pressure (up to 2.5 bars). Both of these aspects have an application to create permanent air layers on ships' hulls. We investigated the effect of pressure on air layers in a pressure cell and exposed the air layer to pressures of up to 6 bars. We investigated the suppression of the air layer at increasing pressures as well as its restoration during decreases in pressure. Three of the four examined Salvinia species are capable of maintaining air layers at pressures relevant to the conditions applying to ships' hulls. High volumes of air per surface area are advantageous for retaining at least a partial Cassie-Baxter-state under pressure, which also helps in restoring the air layer after depressurization. Closed-loop structures such as the baskets at the top of the "egg-beater hairs" (see main text) also help return the air layer to its original level at the tip of the hairs by trapping air bubbles. PMID:24925548

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

    SciTech Connect

    Moore, Murray E.

    2015-02-23

    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 mass 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

  16. PTV analysis of the entrained air into the diesel spray at high-pressure injection

    NASA Astrophysics Data System (ADS)

    Toda, Naoki; Yamashita, Hayato; Mashida, Makoto

    2014-08-01

    In order to clarify the effect of high-pressure injection on soot reduction in terms of the air entrainment into spray, the air flow surrounding the spray and set-off length indicating the distance from the nozzle tip to the flame region in diffusion diesel combustion were investigated using 300MPa injection of a multi-hole injector. The measurement of the air entrainment flow was carried out at non-evaporating condition using consecutive PTV (particle tracking velocimetry) method with a high-speed camera and a high-frequency pulse YAG laser. The set-off length was measured at highpressure and high-temperature using the combustion bomb of constant volume and optical system of shadow graph method. And the amount of air entrainment into spray until reaching set-off length in diffusion combustion was studied as a factor of soot formation.

  17. Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure

    SciTech Connect

    Yatom, S.; Vekselman, V.; Krasik, Ya. E.

    2012-12-15

    Time- and space-resolved fast framing photography was employed to study the discharge initiated by runaway electrons in air and He gas at atmospheric pressure. Whereas in the both cases, the discharge occurs in a nanosecond time scale and its front propagates with a similar velocity along the cathode-anode gap, the later stages of the discharge differ significantly. In air, the main discharge channels develop and remain in the locations with the strongest field enhancement. In He gas, the first, diode 'gap bridging' stage, is similar to that obtained in air; however, the development of the discharge that follows is dictated by an explosive electron emission from micro-protrusions on the edge of the cathode. These results allow us to draw conclusions regarding the different conductivity of the plasma produced in He and air discharges.

  18. Generation of large-area and glow-like surface discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Song, Ying; Xia, Yang; Bi, Zhenhua; Wang, Xueyang; Qi, Zhihua; Ji, Longfei; Li, Bin; Liu, Dongping

    2016-08-01

    A large-area (6 cm × 6 cm) air surface dielectric barrier discharge has been generated at atmospheric pressure by using well-aligned and micron-sized dielectric tubes with tungsten wire electrodes. Intensified CCD images with an exposure time of 5 ns show that the uniform surface air discharge can be generated during the rising and falling time of pulsed DC voltage. Current and voltage and optical measurements confirm the formation of glow-like air discharges on the surface of micron-sized dielectric tubes. Simulation results indicate that the microelectrode configuration contributes to the formation of strong surface electric field and plays an important role in the generation of uniform surface air discharge.

  19. Gas bubble dimensions in Archean lava flows indicate low air pressure at 2.7 Ga

    NASA Astrophysics Data System (ADS)

    Som, S. M.; Buick, R.; Hagadorn, J.; Blake, T.; Perreault, J.; Harnmeijer, J.; Catling, D. C.

    2014-12-01

    Air pressure constrains atmospheric composition, which, in turn, is linked to the Earth system through biogeochemical cycles and fluxes of volatiles from and to the Earth's interior. Previous studies have only placed maximum levels on surface air pressure for the early Earth [1]. Here, we calculate an absolute value for Archean barometric pressure using gas bubble size (vesicle) distributions in uninflated basaltic lava flows that solidified at sea level 2.7 billion years ago in the Pilbara Craton, Western Australia. These vesicles have been filled in by secondary minerals deposited during metasomatism and so are now amydules, but thin sections show that infilling did not change vesicle dimensions. Amygdule dimensions are measured using high-resolution X-ray tomography from core samples obtained from the top and bottom of the lava flows. The modal size expressed at the top and at the bottom of an uninflated flow can be linked to atmospheric pressure using the ideal gas law. Such a technique has been verified as a paleoaltimeter using Hawaiian Quaternary lava flows [2]. We use statistical methods to estimate the mean and standard deviation of the volumetric size of the amygdules by applying 'bootstrap'resampling and the Central Limit Theorem. Our data indicate a surprisingly low atmospheric pressure. Greater nitrogen burial under anaerobic conditions likely explains lower pressure. Refs: [1] Som et al. (2012) Nature 484, 359-262. D. L. Sahagian et al. (2002) J. Geol., 110, 671-685.

  20. Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

    NASA Astrophysics Data System (ADS)

    Cooper, W. A.; Spuler, S. M.; Spowart, M.; Lenschow, D. H.; Friesen, R. B.

    2014-09-01

    A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s-1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents) that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

  1. A Comparative Study of Sound Speed in Air at Room Temperature between a Pressure Sensor and a Sound Sensor

    ERIC Educational Resources Information Center

    Amrani, D.

    2013-01-01

    This paper deals with the comparison of sound speed measurements in air using two types of sensor that are widely employed in physics and engineering education, namely a pressure sensor and a sound sensor. A computer-based laboratory with pressure and sound sensors was used to carry out measurements of air through a 60 ml syringe. The fast Fourier…

  2. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2012-10-01 2012-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC...

  3. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2013-10-01 2013-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC...

  4. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2014-10-01 2014-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC...

  5. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2011-10-01 2011-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC...

  6. Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

    PubMed

    Dockery, D W; Pope, C A; Kanner, R E; Martin Villegas, G; Schwartz, J

    1999-01-01

    Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study.

  7. Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

    PubMed

    Dockery, D W; Pope, C A; Kanner, R E; Martin Villegas, G; Schwartz, J

    1999-01-01

    Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study. PMID:10192116

  8. [Application of Land-use Regression Models in Spatial-temporal Differentiation of Air Pollution].

    PubMed

    Wu, Jian-sheng; Xie, Wu-dan; Li, Jia-cheng

    2016-02-15

    With the rapid development of urbanization, industrialization and motorization, air pollution has become one of the most serious environmental problems in our country, which has negative impacts on public health and ecological environment. LUR model is one of the common methods simulating spatial-temporal differentiation of air pollution at city scale. It has broad application in Europe and North America, but not really in China. Based on many studies at home and abroad, this study started with the main steps to develop LUR model, including obtaining the monitoring data, generating variables, developing models, model validation and regression mapping. Then a conclusion was drawn on the progress of LUR models in spatial-temporal differentiation of air pollution. Furthermore, the research focus and orientation in the future were prospected, including highlighting spatial-temporal differentiation, increasing classes of model variables and improving the methods of model development. This paper was aimed to popularize the application of LUR model in China, and provide a methodological basis for human exposure, epidemiologic study and health risk assessment.

  9. [Application of Land-use Regression Models in Spatial-temporal Differentiation of Air Pollution].

    PubMed

    Wu, Jian-sheng; Xie, Wu-dan; Li, Jia-cheng

    2016-02-15

    With the rapid development of urbanization, industrialization and motorization, air pollution has become one of the most serious environmental problems in our country, which has negative impacts on public health and ecological environment. LUR model is one of the common methods simulating spatial-temporal differentiation of air pollution at city scale. It has broad application in Europe and North America, but not really in China. Based on many studies at home and abroad, this study started with the main steps to develop LUR model, including obtaining the monitoring data, generating variables, developing models, model validation and regression mapping. Then a conclusion was drawn on the progress of LUR models in spatial-temporal differentiation of air pollution. Furthermore, the research focus and orientation in the future were prospected, including highlighting spatial-temporal differentiation, increasing classes of model variables and improving the methods of model development. This paper was aimed to popularize the application of LUR model in China, and provide a methodological basis for human exposure, epidemiologic study and health risk assessment. PMID:27363125

  10. Elevated Plasma Endothelin-1 and Pulmonary Arterial Pressure in Children Exposed to Air Pollution

    PubMed Central

    Calderón-Garcidueñas, Lilian; Vincent, Renaud; Mora-Tiscareño, Antonieta; Franco-Lira, Maricela; Henríquez-Roldán, Carlos; Barragán-Mejía, Gerardo; Garrido-García, Luis; Camacho-Reyes, Laura; Valencia-Salazar, Gildardo; Paredes, Rogelio; Romero, Lina; Osnaya, Hector; Villarreal-Calderón, Rafael; Torres-Jardón, Ricardo; Hazucha, Milan J.; Reed, William

    2007-01-01

    Background Controlled exposures of animals and humans to particulate matter (PM) or ozone air pollution cause an increase in plasma levels of endothelin-1, a potent vasoconstrictor that regulates pulmonary arterial pressure. Objectives The primary objective of this field study was to determine whether Mexico City children, who are chronically exposed to levels of PM and O3 that exceed the United States air quality standards, have elevated plasma endothelin-1 levels and pulmonary arterial pressures. Methods We conducted a study of 81 children, 7.9 ± 1.3 years of age, lifelong residents of either northeast (n = 19) or southwest (n = 40) Mexico City or Polotitlán (n = 22), a control city with PM and O3 levels below the U.S. air quality standards. Clinical histories, physical examinations, and complete blood counts were done. Plasma endothelin-1 concentrations were determined by immunoassay, and pulmonary arterial pressures were measured by Doppler echocardiography. Results Mexico City children had higher plasma endothelin-1 concentrations compared with controls (p < 0.001). Mean pulmonary arterial pressure was elevated in children from both northeast (p < 0.001) and southwest (p < 0.05) Mexico City compared with controls. Endothelin-1 levels in Mexico City children were positively correlated with daily outdoor hours (p = 0.012), and 7-day cumulative levels of PM air pollution < 2.5 μm in aerodynamic diameter (PM2.5) before endothelin-1 measurement (p = 0.03). Conclusions Chronic exposure of children to PM2.5 is associated with increased levels of circulating endothelin-1 and elevated mean pulmonary arterial pressure. PMID:17687455

  11. Study of flow fields induced by surface dielectric barrier discharge actuator in low-pressure air

    SciTech Connect

    Che, Xueke E-mail: st@mail.iee.ac.cn; Nie, Wansheng; Tian, Xihui; Hou, Zhiyong; He, Haobo; Zhou, Penghui; Zhou, Siyin; Yang, Chao; Shao, Tao E-mail: st@mail.iee.ac.cn

    2014-04-15

    Surface dielectric barrier discharge (SDBD) is a promising method for a flow control. Flow fields induced by a SDBD actuator driven by the ac voltage in static air at low pressures varying from 1.0 to 27.7 kPa are measured by the particle image velocimetry method. The influence of the applied ac voltage frequency and magnitude on the induced flow fields is studied. The results show that three different classes of flow fields (wall jet flow field, complex flow field, and vortex-shape flow field) can be induced by the SDBD actuator in the low-pressure air. Among them, the wall jet flow field is the same as the tangential jet at atmospheric pressure, which is, together with the vertical jet, the complex flow field. The vortex-shape flow field is composed of one vertical jet which points towards the wall and two opposite tangential jets. The complex and the vortex-shape flow fields can be transformed to the wall jet flow field when the applied ac voltage frequency and magnitude are changed. It is found that the discharge power consumption increases initially, decreases, and then increases again at the same applied ac voltage magnitude when the air pressure decreases. The tangential velocity of the wall jet flow field increases when the air pressure decreases. It is however opposite for the complex flow field. The variation of the applied ac voltage frequency influences differently three different flow fields. When the applied ac voltage magnitude increases at the same applied ac voltage frequency, the maximal jet velocity increases, while the power efficiency increases only initially and then decreases again. The discharge power shows either linear or exponential dependences on the applied ac voltage magnitude.

  12. Heat transfer and pressure drop for air flow through enhanced passages

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  13. Heat transfer and pressure drop for air flow through enhanced passages. Final report

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  14. Atmospheric pressure air-plasma jet evolved from microdischarges: Eradication of E. coli with the jet

    SciTech Connect

    Hong, Yong Cheol; Kang, Won Seok; Hong, Yoo Beom; Yi, Won Ju; Uhm, Han Sup

    2009-12-15

    An atmospheric-pressure air-plasma jet operating at 60 Hz ac is presented. A plasma jet with a length of 23 mm was produced by feeding air through a porous alumina dielectric installed between an outer electrode and a hollow inner electrode. Microdischarges in the porous alumina are ejected as a plasma jet from the outer electrode through a 1 mm hole, showing that the temperature of the jet decreases to a value close to the room temperature. The jet disinfects E. coli cells very effectively, eradicating them with an exposure of a few seconds to the jet flame.

  15. A plasma needle for generating homogeneous discharge in atmospheric pressure air

    SciTech Connect

    Li Xuechen; Yuan Ning; Jia Pengying; Chen Junying

    2010-09-15

    Homogeneous discharge in air is often considered to be the ultimate low-temperature atmospheric pressure plasmas for industrial applications. In this paper, we present a method whereby stable homogeneous discharge in open air can be generated by a simple plasma needle. The discharge mechanism is discussed based on the spatially resolved light emission waveforms from the plasma. Optical emission spectroscopy is used to determine electron energy and rotational temperature, and results indicate that both electron energy and rotational temperature increase with increasing the applied voltage. The results are analyzed qualitatively based on the discharge mechanism.

  16. Long-Term Air Pollution Exposure and Blood Pressure in the Sister Study

    PubMed Central

    Chan, Stephanie H.; Van Hee, Victor C.; Bergen, Silas; Szpiro, Adam A.; DeRoo, Lisa A.; London, Stephanie J.; Marshall, Julian D.; Sandler, Dale P.

    2015-01-01

    Background Exposure to air pollution has been consistently associated with cardiovascular morbidity and mortality, but mechanisms remain uncertain. Associations with blood pressure (BP) may help to explain the cardiovascular effects of air pollution. Objective We examined the cross-sectional relationship between long-term (annual average) residential air pollution exposure and BP in the National Institute of Environmental Health Sciences’ Sister Study, a large U.S. cohort study investigating risk factors for breast cancer and other outcomes. Methods This analysis included 43,629 women 35–76 years of age, enrolled 2003–2009, who had a sister with breast cancer. Geographic information systems contributed to satellite-based nitrogen dioxide (NO2) and fine particulate matter (≤ 2.5 μm; PM2.5) predictions at participant residences at study entry. Generalized additive models were used to examine the relationship between pollutants and measured BP at study entry, adjusting for cardiovascular disease risk factors and including thin plate splines for potential spatial confounding. Results A 10-μg/m3 increase in PM2.5 was associated with 1.4-mmHg higher systolic BP (95% CI: 0.6, 2.3; p < 0.001), 1.0-mmHg higher pulse pressure (95% CI: 0.4, 1.7; p = 0.001), 0.8-mmHg higher mean arterial pressure (95% CI: 0.2, 1.4; p = 0.01), and no significant association with diastolic BP. A 10-ppb increase in NO2 was associated with a 0.4-mmHg (95% CI: 0.2, 0.6; p < 0.001) higher pulse pressure. Conclusions Long-term PM2.5 and NO2 exposures were associated with higher blood pressure. On a population scale, such air pollution–related increases in blood pressure could, in part, account for the increases in cardiovascular disease morbidity and mortality seen in prior studies. Citation Chan SH, Van Hee VC, Bergen S, Szpiro AA, DeRoo LA, London SJ, Marshall JD, Kaufman JD, Sandler DP. 2015. Long-term air pollution exposure and blood pressure in the Sister Study. Environ Health

  17. System for the automated design on differential-pressure flowmeters with standard constrictors

    SciTech Connect

    Mamonov, Yu.V.; Markov, A.V.; Partrikeev, V.G.; Frenklakh, M.M.

    1995-08-01

    This article examines features of the computing-search subsystem of an automated system for designing differential-pressure flowmeters with standard constrictors. Recent developments within Russia have moved efforts to automate the design and operation of differential-pressure flowmeters (DPF) having a microprocessor-based counter outside the country. The Russian State Commission on Standards therefore assigned the All-Russian Scientific Research Center for Standardization, Information, and Certification of Raw and Processed Materials and Substances (ASRCSMS) the task of developing and introducing standard DPF software based on ISO standards and existing Russian standards. This work was undertaken in accordance with an approved program. Our goal in this article is to substantiate the expediency of developing a system for the automated design of DPFs (DPFADS) to improve on existing practice.

  18. Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength

    PubMed Central

    Kamikawa, Norimichi; Taito, Shunsuke; Takahashi, Makoto; Sekikawa, Kiyokazu; Hamada, Hironobu

    2016-01-01

    Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a “hard” and “soft” mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in “soft” than in “hard” mode. The differences between the sinking distances of the mattress in “soft” and “hard” modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense. PMID:26741497

  19. Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength.

    PubMed

    Kamikawa, Norimichi; Taito, Shunsuke; Takahashi, Makoto; Sekikawa, Kiyokazu; Hamada, Hironobu

    2016-01-01

    Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a "hard" and "soft" mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in "soft" than in "hard" mode. The differences between the sinking distances of the mattress in "soft" and "hard" modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense. PMID:26741497

  20. Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength.

    PubMed

    Kamikawa, Norimichi; Taito, Shunsuke; Takahashi, Makoto; Sekikawa, Kiyokazu; Hamada, Hironobu

    2016-01-01

    Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a "hard" and "soft" mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in "soft" than in "hard" mode. The differences between the sinking distances of the mattress in "soft" and "hard" modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense.

  1. Differential absorption lidars for remote sensing of atmospheric pressure and temperature profiles

    NASA Technical Reports Server (NTRS)

    Korb, C. Laurence; Schwemmer, Geary K.; Famiglietti, Joseph; Walden, Harvey; Prasad, Coorg

    1995-01-01

    A near infrared differential absorption lidar technique is developed using atmospheric oxygen as a tracer for high resolution vertical profiles of pressure and temperature with high accuracy. Solid-state tunable lasers and high-resolution spectrum analyzers are developed to carry out ground-based and airborne measurement demonstrations and results of the measurements presented. Numerical error analysis of high-altitude airborne and spaceborne experiments is carried out, and system concepts developed for their implementation.

  2. Experimental Study on a Standing Wave Thermoacoustic Prime Mover with Air Working Gas at Various Pressures

    NASA Astrophysics Data System (ADS)

    Setiawan, Ikhsan; Achmadin, Wahyu N.; Murti, Prastowo; Nohtomi, Makoto

    2016-04-01

    Thermoacoustic prime mover is an energy conversion device which converts thermal energy into acoustic work (sound wave). The advantages of this machine are that it can work with air as the working gas and does not produce any exhaust gases, so that it is environmentally friendly. This paper describes an experimental study on a standing wave thermoacoustic prime mover with air as the working gas at various pressures from 0.05 MPa to 0.6 MPa. We found that 0.2 MPa is the optimum pressure which gives the lowest onset temperature difference of 355 °C. This pressure value would be more preferable in harnessing low grade heat sources to power the thermoacoustic prime mover. In addition, we find that the lowest onset temperature difference is obtained when rh /δ k ratio is 2.85, where r h is the hydraulic radius of the stack and δ k is the thermal penetration depth of the gas. Moreover, the pressure amplitude of the sound wave is significantly getting larger from 2.0 kPa to 9.0 kPa as the charged pressure increases from 0.05 MPa up to 0.6 MPa.

  3. Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

    NASA Astrophysics Data System (ADS)

    Cooper, W. A.; Spuler, S. M.; Spowart, M.; Lenschow, D. H.; Friesen, R. B.

    2014-03-01

    A new laser air-motion sensor measures the true airspeed with an uncertainty of less than 0.1 m s-1 (standard error) and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard-error uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the Global Positioning System, then indicate (via integrations of the hydrostatic equation during climbs and descents) that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that the new laser air-motion sensor, combined with parametrized fits to correction factors for the measured dynamic and ambient pressure, provides a measurement of temperature that is independent of any other temperature sensor.

  4. Investigation of air solubility in jet A fuel at high pressures

    NASA Technical Reports Server (NTRS)

    Rupprecht, S. D.; Faeth, G. M.

    1981-01-01

    The solubility and density properties of saturated mixtures of fuels and gases were measured. The fuels consisted of Jet A and dodecane, the gases were air and nitrogen. The test range included pressures of 1.03 to 10.34 MPa and temperatures of 298 to 373 K. The results were correlated successfully, using the Soave equation of state. Over this test range, dissolved gas concentrations were roughly proportional to pressure and increased slightly with increasing temperature. Mixture density was relatively independent of dissolved gas concentration.

  5. Air-pressure tunable depletion width, rectification behavior, and charge conduction in oxide nanotubes.

    PubMed

    Alivov, Yahya; Funke, Hans H; Singh, Vivek; Nagpal, Prashant

    2015-02-01

    Metal-oxide nanotubes provide large surface areas and functionalizable surfaces for a variety of optical and electronic applications. Here we report air-tunable rectifying behavior, depletion width modulation, and two-dimensional (2D) charge conduction in hollow titanium-dioxide nanotubes. The metal contact forms a Schottky-diode in the nanotubes, and the rectification factor (on/off ratio) can be varied by more than 3 orders of magnitude (1-2 × 10(3)) as the air pressure is increased from 2 mTorr to atmospheric pressure. This behavior is explained using a change in depletion width of these thin nanotubes by adsorption of water vapor on both surfaces of a hollow nanotube, and the resulting formation of a metal-insulator-semiconductor (MIS) junction, which controls the 2D charge conduction properties in thin oxide nanotubes.

  6. Evaluation of analytical methodology for hydrocarbons in high pressure air and nitrogen systems. [evaluation of methodology

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Samples of liquid oxygen, high pressure nitrogen, low pressure nitrogen, and missile grade air were studied to determine the hydrocarbon concentrations. Concentration of the samples was achieved by adsorption on a molecular sieve and activated charcoal. The trapped hydrocarbons were then desorbed and transferred to an analytical column in a gas chromatograph. The sensitivity of the method depends on the volume of gas passed through the adsorbent tubes. The value of the method was verified through recoverability and reproducibility studies. The use of this method enables LOX, GN2, and missile grade air systems to be routinely monitored to determine low level increases in specific hydrocarbon concentration that could lead to potentially hazardous conditions.

  7. Parameters of a supershort avalanche electron beam generated in atmospheric-pressure air

    SciTech Connect

    Tarasenko, V. F.

    2011-05-15

    Conditions under which the number of runaway electrons in atmospheric-pressure air reaches {approx}5 Multiplication-Sign 10{sup 10} are determined. Recommendations for creating runaway electron accelerators are given. Methods for measuring the parameters of a supershort avalanche electron beam and X-ray pulses from gas-filled diodes, as well as the discharge current and gap voltage, are described. A technique for determining the instant of runaway electron generation with respect to the voltage pulse is proposed. It is shown that the reduction in the gap voltage and the decrease in the beam current coincide in time. The mechanism of intense electron beam generation in gas-filled diodes is analyzed. It is confirmed experimentally that, in optimal regimes, the number of electrons generated in atmospheric-pressure air with energies T > eU{sub m}, where U{sub m} is the maximum gap voltage, is relatively small.

  8. Parameters of a supershort avalanche electron beam generated in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.

    2011-05-01

    Conditions under which the number of runaway electrons in atmospheric-pressure air reaches ˜5 × 1010 are determined. Recommendations for creating runaway electron accelerators are given. Methods for measuring the parameters of a supershort avalanche electron beam and X-ray pulses from gas-filled diodes, as well as the discharge current and gap voltage, are described. A technique for determining the instant of runaway electron generation with respect to the voltage pulse is proposed. It is shown that the reduction in the gap voltage and the decrease in the beam current coincide in time. The mechanism of intense electron beam generation in gas-filled diodes is analyzed. It is confirmed experimentally that, in optimal regimes, the number of electrons generated in atmospheric-pressure air with energies T > eU m , where U m is the maximum gap voltage, is relatively small.

  9. Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2015-09-01

    In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

  10. Differential contributions of theobromine and caffeine on mood, psychomotor performance and blood pressure.

    PubMed

    Mitchell, E S; Slettenaar, M; vd Meer, N; Transler, C; Jans, L; Quadt, F; Berry, M

    2011-10-24

    The combination of theobromine and caffeine, methylxanthines found in chocolate, has previously been shown to improve mood and cognition. However, it is unknown whether these molecules act synergistically. This study tested the hypothesis that a combination of caffeine and theobromine has synergistic effects on cognition, mood and blood pressure in 24 healthy female subjects. The effects of theobromine (700 mg), caffeine (120 mg) or the combination of both, or placebo were tested on mood (the Bond-Lader visual analog scale), psychomotor performance (the Digit Symbol Substitution Test (DSST)) and blood pressure before and at 1, 2 and 3 h after administration. Theobromine alone decreased self-reported calmness 3h after ingestion and lowered blood pressure relative to placebo 1 h after ingestion. Caffeine increased self-reported alertness 1, 2 and 3h after ingestion and contentedness 1 and 2 h after ingestion, and increased blood pressure relative to placebo (at 1 h). The combination of caffeine+theobromine had similar effects as caffeine alone on mood, but with no effect on blood pressure. There was no treatment effect on DSST performance. Together these results suggest that theobromine and caffeine could have differential effects on mood and blood pressure. It was tentatively concluded that caffeine may have more CNS-mediated effects on alertness, while theobromine may be acting primarily via peripheral physiological changes.

  11. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    NASA Astrophysics Data System (ADS)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  12. Ozone production by nanoporous dielectric barrier glow discharge in atmospheric pressure air

    SciTech Connect

    Cho, J. H.; Koo, I. G.; Choi, M. Y.; Lee, W. M.

    2008-03-10

    This study is aimed at demonstrating plasma-chemical ozone production based on low temperature atmospheric pressure glow discharge through nanoporous dielectric barriers. The 20 kHz ac driven discharge is formed in air or oxygen gas flowing in the axial direction of the cylindrical plasma reactor containing four parallel aluminum rods covered with nanoporous alumina films. The discharge utilizing nanoporous dielectric barrier is more uniform and more energy efficient in ozone generation than the discharge through smooth-surface dielectric barriers.

  13. Characteristics of a glow discharge in atmospheric pressure air over the water surface

    NASA Astrophysics Data System (ADS)

    Shuaibov, A. K.; Chuchman, M. P.; Mesarosh, L. V.

    2014-06-01

    The current-voltage characteristics, the amount of cathode fall, and the spectra of plasma radiation from different spatial domains are presented versus the molecular band intensity of products arising in an atmospheric-pressure air glow discharge over the distilled water surface. The plasma electron temperature is also reported. The distance to a liquid cathode or anode is varied from 1 to 10 mm at a discharge mean current of 10-36 mA.

  14. Travel of the center of pressure of airfoils transversely to the air stream

    NASA Technical Reports Server (NTRS)

    Katzmayr, Richard

    1929-01-01

    The experiments here described were performed for the purpose of obtaining the essential facts concerning the distribution of the air force along the span. We did not follow, however, the time-consuming method of point-to-point measurements of the pressure distribution on the wing surfaces, but determined directly the moment of mean force about an axis passing through the middle of the span parallel to the direction of flight.

  15. Vibration and recoil control of pneumatic hammers. [by air flow pressure regulation

    NASA Technical Reports Server (NTRS)

    Constantinescu, I. N.; Darabont, A. V.

    1974-01-01

    Vibration sources are described for pneumatic hammers used in the mining industry (pick hammers), in boiler shops (riveting hammers), etc., bringing to light the fact that the principal vibration source is the variation in air pressure inside the cylinder. The present state of the art of vibration control of pneumatic hammers as it is practiced abroad, and the solutions adopted for this purpose, are discussed. A new type of pneumatic hammer with a low noise and vibration level is presented.

  16. Measurement of Electron Densities in a Pulsed Atmospheric Pressure Air Discharge

    NASA Astrophysics Data System (ADS)

    Leipold, Frank; Stark, Robert H.; Schoenbach, Karl H.

    2000-10-01

    Microhollow cathode discharges have been shown to serve as plasma cathodes for atmospheric pressure air discharges [1]. The high pressure discharges are operated dc at currents from 10 mA up to 30 mA and at average electric fields of 1.25 kV/cm. The electron density in the dc discharge was measured by an interferometrique technique [2]. For a dc filamentary air discharge with a current of 10 mA, the radial electron density distribution was found to be parabolic with a total width of 660 μ m and an electron density of ne = 10^13 cm-3 in the center of the discharge. The diagnostic technique has now also been applied to pulsed discharges. It was found that the method provides electron densities measurements for discharges with durations as low as 5 μ s. The spatial distribution of the index of refraction in the pulsed discharge was obtained by shifting the discharge volume through the laser beam and by using an inversion method to obtain the radial index profile. For the electron density with a assumed parabolic profile, the maximum value was measured as 1.17*10^14 cm-3. (10 mA atmospheric pressure air discharge. The temperature profile was found to be gaussian with a half width of 1.3 mm. Acknowledgement This work was funded by the Air Force Office of Scientific Research in Cooperation with the DDR&E Air Plasma Ramparts MURI Program. References [1] Robert H. Stark and Karl H. Schoenbach, Appl. Phys. Lett. 74, 3770 (1999) [2] Frank Leipold, Robert H. Stark, and Karl H. Schoenbach, to appear in J. Phys. D., Appl. Phys.

  17. Three-Dimensional Modelling inside a Differential Pressure Laminar Flow Bioreactor Filled with Porous Media.

    PubMed

    Weyand, Birgit; Israelowitz, Meir; Kramer, James; Bodmer, Christian; Noehre, Mariel; Strauss, Sarah; Schmälzlin, Elmar; Gille, Christoph; von Schroeder, Herbert P; Reimers, Kerstin; Vogt, Peter M

    2015-01-01

    A three-dimensional computational fluid dynamics- (CFD-) model based on a differential pressure laminar flow bioreactor prototype was developed to further examine performance under changing culture conditions. Cell growth inside scaffolds was simulated by decreasing intrinsic permeability values and led to pressure build-up in the upper culture chamber. Pressure release by an integrated bypass system allowed continuation of culture. The specific shape of the bioreactor culture vessel supported a homogenous flow profile and mass flux at the scaffold level at various scaffold permeabilities. Experimental data showed an increase in oxygen concentration measured inside a collagen scaffold seeded with human mesenchymal stem cells when cultured in the perfusion bioreactor after 24 h compared to static culture in a Petri dish (dynamic: 11% O2 versus static: 3% O2). Computational fluid simulation can support design of bioreactor systems for tissue engineering application.

  18. Evaluation of the operator protection factors offered by positive pressure air suits against airborne microbiological challenge.

    PubMed

    Steward, Jackie A; Lever, Mark S

    2012-08-01

    Laboratories throughout the world that perform work with Risk Group 4 Pathogens generally adopt one of two approaches within BSL-4 environments: either the use of positive pressure air-fed suits or using Class III microbiological safety cabinets and isolators for animal work. Within the UK at present, all laboratories working with Risk Group 4 agents adopt the use of Class III microbiological safety cabinet lines and isolators. Operator protection factors for the use of microbiological safety cabinets and isolators are available however; there is limited published data on the operator protection factors afforded by the use of positive pressure suits. This study evaluated the operator protection factors provided by positive pressure air suits against a realistic airborne microbiological challenge. The suits were tested, both intact and with their integrity compromised, on an animated mannequin within a stainless steel exposure chamber. The suits gave operator protection in all tests with an intact suit and with a cut in the leg. When compromised by a cut in the glove, a very small ingress of the challenge was seen as far as the wrist. This is likely to be due to the low airflow in the gloves of the suit. In all cases no microbiological penetration of the respiratory tract was observed. These data provide evidence on which to base safety protocols for use of positive pressure suits within high containment laboratories. PMID:23012620

  19. Evaluation of the Operator Protection Factors Offered by Positive Pressure Air Suits against Airborne Microbiological Challenge

    PubMed Central

    Steward, Jackie A.; Lever, Mark S.

    2012-01-01

    Laboratories throughout the world that perform work with Risk Group 4 Pathogens generally adopt one of two approaches within BSL-4 environments: either the use of positive pressure air-fed suits or using Class III microbiological safety cabinets and isolators for animal work. Within the UK at present, all laboratories working with Risk Group 4 agents adopt the use of Class III microbiological safety cabinet lines and isolators. Operator protection factors for the use of microbiological safety cabinets and isolators are available however; there is limited published data on the operator protection factors afforded by the use of positive pressure suits. This study evaluated the operator protection factors provided by positive pressure air suits against a realistic airborne microbiological challenge. The suits were tested, both intact and with their integrity compromised, on an animated mannequin within a stainless steel exposure chamber. The suits gave operator protection in all tests with an intact suit and with a cut in the leg. When compromised by a cut in the glove, a very small ingress of the challenge was seen as far as the wrist. This is likely to be due to the low airflow in the gloves of the suit. In all cases no microbiological penetration of the respiratory tract was observed. These data provide evidence on which to base safety protocols for use of positive pressure suits within high containment laboratories. PMID:23012620

  20. The role of air pressure and contact force in shaping obstruent consonant onset

    NASA Astrophysics Data System (ADS)

    Chen, Lan

    2003-04-01

    Soft tissues (the tongue or lips) are used to form the narrow oral constriction for turbulence noise generation during the production of obstruent consonants. The displacement of the soft tissue subject to oral pressure buildup is comparable to the vertical dimension of the constriction. The contact force during the closure of stop consonants and affricates provides a pressure load over 5 times larger than the air pressure at the surface in contact. It can influence the time variation of the constriction size at onset in the form of elastic energy stored in the compliant structure forming the constriction. A finite element fluid-structure interaction program has been used to simulate the effect of these external forces during the onset of obstruent consonants. Preliminary results from a 2-D tongue tip constriction/closure model show that air pressure and contact force can introduce movement on the order of 0.1-0.2 mm during the first tens of milliseconds after release, which is enough to affect the size of the constriction at onset and the nature of release burst. The results of this kind can be used for speech synthesis, guiding the modification of the trajectories of articulators at the consonant onset. [Work supported by NIH.

  1. Pattern recognition techniques for visualizing the biotropic waveform of air temperature and pressure

    NASA Astrophysics Data System (ADS)

    Ozheredov, V. A.

    2012-12-01

    It is known that long periods of adverse weather have a negative effect on the human cardiovascular system. A number of studies have set a lower limit of around 5 days for the duration of these periods. However, the specific features of the negative dynamics of the main weather characteristics—air temperature and atmospheric pressure—remained open. To address this problem, the present paper proposes a conjunctive method of the theory of pattern recognition. It is shown that this method approaches a globally optimal (in the sense of recognition errors) Neumann critical region and can be used to solve various problems in heliobiology. To illustrate the efficiency of this method, we show that some quickly relaxing short sequences of temperature and pressure time series (the so-called temperature waves and waves of atmospheric pressure changes) increase the risk of cardiovascular diseases and can lead to serious organic lesions (particularly myocardial infarction). It is established that the temperature waves and waves of atmospheric pressure changes increase the average morbidity rate of myocardial infarction by 90% and 110%, respectively. Atmospheric pressure turned out to be a more biotropic factor than air temperature.

  2. Progressive resistance neck exercises using a compressible ball coupled with an air pressure gauge.

    PubMed

    Axen, K; Haas, F; Schicchi, J; Merrick, J

    1992-01-01

    Strength training of neck muscles, a potentially important approach to injury prevention and rehabilitation, has been limited by the lack of a convenient means of instituting progressive resistance exercise (PRE) programs. By positioning a compressible ball coupled with an air pressure gauge between the head and a wall, eight men, ranging in age from 21 to 46 years, initially measured the maximum voluntary pressure (MVP) generated within the ball (a measure of neck muscle force), while maximally flexing, extending, and laterally flexing their head into the ball. In accordance with PRE principles, they then performed three sets of 10 repetitions of each motion while maintaining ball pressure at 60-80% of the measured MVP. This training program, consisting of three to five sessions per week for 4-7 weeks: 1) increased the MVPs for flexion [to 156 +/- 9% (SE) pretraining, p < 0.05], extension [to 162 +/- 11% (SE) pretraining, p < 0.05], and lateral flexion [to 173 +/- 12% (SE) pretraining, p < 0.05]; and 2) decreased the disparity between the MVPs for left and right lateral flexion, indicating that the weaker side showed greater improvement than the stronger side (p < 0.05). These findings demonstrate that progressive resistance neck exercises, facilitated by a compressible ball coupled with an air pressure gauge, can markedly increase neck muscle strength and decrease lateral force imbalance. J Orthop Sports Phys Ther 1992;16(6):275-280.

  3. Soot formation in turbulent nonpremixed kerosine-air flames burning at elevated pressure: Experimental measurement

    SciTech Connect

    Young, K.J.; Stewart, C.D.; Moss, J.B.

    1994-12-31

    Detailed scalar property maps have been constructed for turbulent jet flames of prevaporized kerosine, burning in a coflowing air stream and confined within an optically accessed cylindrical chamber, which permits operation at elevated pressure. Time-averaged measurements of spatially resolved soot volume fraction by path-integrated laser absorption and tomographic inversion, temperature by fine wire thermocouple, and mixture fraction by microprobe sampling and mass spectrometric analysis are reported at chamber pressures from 1 to 6.4 bar. While the principal objective of the study has been to develop a database for modelling and computational prediction, the centerline data admit presentation in a standardized form, based on the centerline flame length to the maximum soot concentration, which permits analysis of the pressure dependence from turbulent flames of differing sizes. In this form, the peak soot volume fractions and soot formation rates appear linearly dependent on pressure, exhibiting a peak mass fraction of soot carbon of 7%, substantially independent of pressure. The peak soot loading, at the highest pressure investigated, approaches 120 gm{sup {minus}3} before complete laser extinction renders the flame inaccessible to further measurement. The high carbon loading and enhanced radiative loss lead to reduced mean temperatures throughout the flame by comparison with more widely studied gaseous fuels such as ethylene. Measured temperatures do not exceed 1,438 K anywhere on the centerline of the flame at 1 bar, for example.

  4. Surface Pressure Study of Lipid Aggregates at the Air Water Interface

    NASA Astrophysics Data System (ADS)

    Shew, Woody; Ploplis Andrews, Anna

    1996-11-01

    Qualitative and quantitative descriptions of the growth of fatty acid aggregates on a water/air interface were made by analyzing surface pressure measurements taken with a Langmuir Balance. High concentrations of palmitic acid, lauric acid, myristic acid, and also phosphatidylethanolamine in solution with chloroform were applied with a syringe to the surface of the Langmuir Balance and surface pressure was monitored as aggregates assembled spontaneously. The aggregation process for palmitic acid was determined to consist of three distinct parts. Exponential curves were fit to the individual regions of the data and growth and decay constants were determined. Surface pressure varied in very complex ways for lauric acid, myristic acid, and phosphatidylethanolamine yet kinetic measurements yield qualitative information about assembly of those aggregates. This research was supported by NSF Grant No. DMR-93-22301.

  5. Advancing a smart air cushion system for preventing pressure ulcers using projection Moiré for large deformation measurements

    NASA Astrophysics Data System (ADS)

    Cheng, Sheng-Lin; Tsai, Tsung-Heng; Lee, Carina Jean-Tien; Hsu, Yu-Hsiang; Lee, Chih-Kung

    2016-03-01

    A pressure ulcer is one of the most important concerns for wheelchair bound patients with spinal cord injuries. A pressure ulcer is a localized injury near the buttocks that bear ischial tuberosity oppression over a long period of time. Due to elevated compression to blood vessels, the surrounding tissues suffer from a lack of oxygen and nutrition. The ulcers eventually lead to skin damage followed by tissue necrosis. The current medical strategy is to minimize the occurrence of pressure ulcers by regularly helping patients change their posture. However, these methods do not always work effectively or well. As a solution to fundamentally prevent pressure ulcers, a smart air cushion system was developed to detect and control pressure actively. The air cushion works by automatically adjusting a patient's sitting posture to effectively relieve the buttock pressure. To analyze the correlation between the dynamic pressure profiles of an air cell with a patient's weight, a projection Moiré system was adopted to measure the deformation of an air cell and its associated stress distribution. Combining a full-field deformation imaging with air pressure measured within an air cell, the patient's weight and the stress distribution can be simultaneously obtained. By integrating a full-field optical metrology with a time varying pressure sensor output coupled with different active air control algorithms for various designs, we can tailor the ratio of the air cells. Our preliminary data suggests that this newly developed smart air cushion has the potential to selectively reduce localized compression on the tissues at the buttocks. Furthermore, it can take a patient's weight which is an additional benefit so that medical personnel can reference it to prescribe the correct drug dosages.

  6. Simplified Configuration for the Combustor of an oil Burner using a low Pressure, high flow air-atomizing Nozzle

    SciTech Connect

    Butcher, Thomas; Celebi, Yusuf; Fisher, Leonard

    1998-09-28

    The invention relates to clean burning of fuel oil with air. More specifically, to a fuel burning combustion head using a low-pressure, high air flow atomizing nozzle so that there will be a complete combustion oil resulting in a minimum emission of pollutants. The inventors have devised a fuel burner that uses a low pressure air atomizing nozzle. The improved fuel burner does not result in the use of additional compressors or the introduction of pressurized gases downstream, nor does it require a complex design.

  7. Fiber in-line Mach-Zehnder interferometer based on an inner air-cavity for high-pressure sensing.

    PubMed

    Talataisong, W; Wang, D N; Chitaree, R; Liao, C R; Wang, C

    2015-04-01

    We demonstrate a fiber in-line Mach-Zehnder interferometer based on an inner air-cavity with open micro-channel for high-pressure sensing applications. The inner air-cavity is fabricated by combining femtosecond laser micromachining and the fusion splicing technique. The micro-channel is drilled on the top of the inner air-cavity to allow the high-pressure gas to flow in. The fiber in-line device is miniature, robust, and stable in operation and exhibits a high pressure sensitivity of ∼8,239  pm/MPa.

  8. Drag Reduction Study by Wavelet Analysis of Differential Pressure Signals in Turbulent Flow

    SciTech Connect

    Ling Zhen; Yassin, A. Hassan; Dominguez-Ontiveros, Elvis

    2004-07-01

    Drag reduction was studied when micro-bubbles with low void fractions were injected in the boundary layer of a turbulent channel flow. The particle tracking velocimetry (PIV) flow measurement technique was used to measure two-dimensional full velocity fields. Since pressure field distribution is associated with turbulence behavior and dissipation, it is important to study the changes of the pressure field. However, the differential pressure signals are difficult to analyze due to irregularity. The characteristics of these signals have been studied by traditional statistical methods. In this study, the multi-resolution technique of wavelet transform based on localized wavelet functions is utilized to nonlinear pressure signals. By using continuous wavelet transform method, the pressure signals in the turbulent flow can be decomposed into its approximations and details at different resolutions. The magnitudes of the coefficients represent the energy distribution at different scales and this also can facilitate the visual observation of the energy transition process. The wavelet decomposition coefficients at different scales plot would provide a tool to further our understanding of drag reduction mechanism via micro-bubbles injection. (authors)

  9. Seasonal emanation of radon at Ghuttu, northwest Himalaya: Differentiation of atmospheric temperature and pressure influences.

    PubMed

    Kamra, Leena

    2015-11-01

    Continuous monitoring of radon along with meteorological parameters has been carried out in a seismically active area of Garhwal region, northwest Himalaya, within the frame work of earthquake precursory research. Radon measurements are carried out by using a gamma ray detector installed in the air column at a depth of 10m in a 68m deep borehole. The analysis of long time series for 2006-2012 shows strong seasonal variability masked by diurnal and multi-day variations. Isolation of a seasonal cycle by minimising short-time by 31 day running average shows a strong seasonal variation with unambiguous dependence on atmospheric temperature and pressure. The seasonal characteristics of radon concentrations are positively correlated to atmospheric temperature (R=0.95) and negatively correlated to atmospheric pressure (R=-0.82). The temperature and pressure variation in their annual progressions are negatively correlated. The calculations of partial correlation coefficient permit us to conclude that atmospheric temperature plays a dominant role in controlling the variability of radon in borehole, 71% of the variability in radon arises from the variation in atmospheric temperature and about 6% of the variability is contributed by atmospheric pressure. The influence of pressure variations in an annual cycle appears to be a pseudo-effect, resulting from the negative correlation between temperature and pressure variations. Incorporation of these results explains the varying and even contradictory claims regarding the influence of the pressure variability on radon changes in the published literature. Temperature dependence, facilitated by the temperature gradient in the borehole, controls the transportation of radon from the deep interior to the surface.

  10. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures.

    PubMed

    Aleksandrov, N L; Bodrov, S B; Tsarev, M V; Murzanev, A A; Sergeev, Yu A; Malkov, Yu A; Stepanov, A N

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ∼3% O_{2}), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures. PMID:27575227

  11. Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Krueger, Ronald; Ratcliffe, James

    2013-01-01

    The ground-air pressurization of lightweight honeycomb sandwich structures caused by alternating pressure differences between the enclosed air within the honeycomb core and the ambient environment is a well-known and controllable loading condition of aerospace structures. However, initial face sheet/core disbonds intensify the face sheet peeling effect of the internal pressure load significantly and can decrease the reliability of the sandwich structure drastically. Within this paper, a numerical parameter study was carried out to investigate the criticality of initial disbonds in honeycomb sandwich structures under ground-air pressurization. A fracture mechanics approach was used to evaluate the loading at the disbond front. In this case, the strain energy release rate was computed via the Virtual Crack Closure Technique. Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed.

  12. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures

    NASA Astrophysics Data System (ADS)

    Aleksandrov, N. L.; Bodrov, S. B.; Tsarev, M. V.; Murzanev, A. A.; Sergeev, Yu. A.; Malkov, Yu. A.; Stepanov, A. N.

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ˜3% O2), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures.

  13. Change in endotracheal tube cuff pressure during nitrous oxide anaesthesia: a comparison between air and distilled water cuff inflation.

    PubMed

    Ahmad, N L; Norsidah, A M

    2001-10-01

    In this prospective, randomized controlled trial, changes in endotracheal tube cuff pressure were studied in 60 patients undergoing elective surgery under general anaesthesia with nitrous oxide and oxygen. The cuffs were inflated with either air or distilled water. The mean pressure in the air-filled cuffs increased steadily throughout the procedure, reaching 47.5 +/- 7.3 cmH2O at one hour compared with 31.6 +/- 2.4 cmH2O mean pressure in the water-filled cuffs. The pressure and the rate of rise in cuff pressure were significantly lower (P<0.05) in the water-filled cuffs throughout the hour of study. When an endotracheal tube cuff is distended with water, the rise in cuff pressure during nitrous oxide anaesthesia is lower than that of an air-filled cuff.

  14. [Air pollutants study by differential optical absorption spectroscopy with transmit-receive fibers].

    PubMed

    Wei, Yong-Jie; Geng, Xiao-Juan; Chen, Bo; Liu, Cui-Cui; Chen, Wen-Liang

    2013-10-01

    The differential optical absorption spectroscopy system is presented to monitor air pollutants, such as SO2, NO2, etc. The system employs a reflective telescope to collimate light source and focus absorbed light. A combined transmitting and receiving fiber bundle is set to the focus of a concave mirror. A Xenon lamp works as the light source. The light is coupled into the transmitting fiber, and then collimated by the reflective telescope system. After absorbed by the pollutants, the light is reflected by a pyramid mirror far away the telescope. Then the absorbed light is incident on the concave mirror the second time, and focused on the focal plane again. The receiving fiber induces the light which carries the information of the measured gas into a spectrometer. We can get the concentration of the pollutants by DOAS algorithm. Experimental results show that the proposed method can be adopted to measure some pollutants in air quality monitoring.

  15. [Air pollutants study by differential optical absorption spectroscopy with transmit-receive fibers].

    PubMed

    Wei, Yong-Jie; Geng, Xiao-Juan; Chen, Bo; Liu, Cui-Cui; Chen, Wen-Liang

    2013-10-01

    The differential optical absorption spectroscopy system is presented to monitor air pollutants, such as SO2, NO2, etc. The system employs a reflective telescope to collimate light source and focus absorbed light. A combined transmitting and receiving fiber bundle is set to the focus of a concave mirror. A Xenon lamp works as the light source. The light is coupled into the transmitting fiber, and then collimated by the reflective telescope system. After absorbed by the pollutants, the light is reflected by a pyramid mirror far away the telescope. Then the absorbed light is incident on the concave mirror the second time, and focused on the focal plane again. The receiving fiber induces the light which carries the information of the measured gas into a spectrometer. We can get the concentration of the pollutants by DOAS algorithm. Experimental results show that the proposed method can be adopted to measure some pollutants in air quality monitoring. PMID:24409736

  16. [Transport and differentiation of polycyclic aromatic hydrocarbons in air from Dashiwei karst Sinkholes in Guangxi, China].

    PubMed

    Kong, Xiang-Sheng; Qi, Shi-Hua; Sun, Qian; Huang, Bao-Jian

    2012-12-01

    The typical karst Dashiwei Sinkholes located in Leye County, Guangxi were chosen as the study object. The air samples from the opening of Dashiwei Sinkholes to the underground river profiles were collected by polyurethane foam passive samplers (PUF-PAS), and the meteorological parameters were observed. The 16 PAHs were analyzed using GC-MS. The results showed that the total PAHs concentration in air in Dashiwei Sinkholes ranged from 33.76 ng x d(-1) to 150.86 ng x d(-1), with an average of 80.36 ng x d(-1). The mean concentrations in the cliff, the bottom and the underground river profiles were 67.17, 85.36 and 101.67 ng x d(-1), respectively. The 2-3 rings PAHs (including phenanthrene, anthracene, napnthalene and fluorene) accounted for 87.97% of the total of PAHs. The transport and accumulation processes of PAHs in air in Dashiwei Sinkholes were: the ground to the cliff section to the bottom section and then to the underground river, and the total PAHs concentrations showed an obvious increasing tendency with the decrease in altitude or increase in the length of the underground river. Low molecular weight PAHs compounds (including phenanthrene, anthracene, flourene and fluoranthene) in air went through differentiation at the bottom of the west peak, the bottom of the sinkhole and the underground river. The primary sources of PAHs were pyrogenic sources with atmosphere transport. Ambient temperature was the predominating factor influencing the transport and accumulation of gas phase PAHs in Dashiwei Sinkholes, following by wind speed, wind direction and relative humidity. Relative humidity and the temperature were the predominating factors influencing the differentiation, following by wind speed and wind direction. As a whole, a "cold trapping effect" of POPs was showed obviously in Dashiwei Sinkholes.

  17. An Analytical Solution for Mechanical Responses Induced by Temperature and Air Pressure in a Lined Rock Cavern for Underground Compressed Air Energy Storage

    NASA Astrophysics Data System (ADS)

    Zhou, Shu-Wei; Xia, Cai-Chu; Du, Shi-Gui; Zhang, Ping-Yang; Zhou, Yu

    2015-03-01

    Mechanical responses induced by temperature and air pressure significantly affect the stability and durability of underground compressed air energy storage (CAES) in a lined rock cavern. An analytical solution for evaluating such responses is, thus, proposed in this paper. The lined cavern of interest consists of three layers, namely, a sealing layer, a concrete lining and the host rock. Governing equations for cavern temperature and air pressure, which involve heat transfer between the air and surrounding layers, are established first. Then, Laplace transform and superposition principle are applied to obtain the temperature around the lined cavern and the air pressure during the operational period. Afterwards, a thermo-elastic axisymmetrical model is used to analytically determine the stress and displacement variations induced by temperature and air pressure. The developments of temperature, displacement and stress during a typical operational cycle are discussed on the basis of the proposed approach. The approach is subsequently verified with a coupled compressed air and thermo-mechanical numerical simulation and by a previous study on temperature. Finally, the influence of temperature on total stress and displacement and the impact of the heat transfer coefficient are discussed. This paper shows that the temperature sharply fluctuates only on the sealing layer and the concrete lining. The resulting tensile hoop stresses on the sealing layer and concrete lining are considerably large in comparison with the initial air pressure. Moreover, temperature has a non-negligible effect on the lined cavern for underground compressed air storage. Meanwhile, temperature has a greater effect on hoop and longitudinal stress than on radial stress and displacement. In addition, the heat transfer coefficient affects the cavern stress to a higher degree than the displacement.

  18. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  19. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test... for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with...

  20. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test... for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with...

  1. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test... for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with...

  2. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test... for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with...

  3. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test... for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with...

  4. Hydrogen Adsorption on Activated Carbon an Carbon Nanotubes Using Volumetric Differential Pressure Technique

    SciTech Connect

    Sanip, S. M.; Saidin, M. A. R.; Aziz, M.; Ismail, A. F.

    2010-03-11

    A simple hydrogen adsorption measurement system utilizing the volumetric differential pressure technique has been designed, fabricated and calibrated. Hydrogen adsorption measurements have been carried out at temperatures 298 K and 77 K on activate carbon and carbon nanotubes with different surface areas. The adsorption data obtained will be helpful in understanding the adsorption property of the studied carbon materials using the fundamentals of adsorption theory. The principle of the system follows the Sievert-type method. The system measures a change in pressure between the reference cell, R1 and the sample cell S1, S2, S3 over a certain temperature range, R1, S1, S2, and S3 having known fixed volume. The sample temperatures will be monitored by thermocouple TC while the pressures in R1 an S1, S2, S3 will be measured using a digital pressure transducer. The maximum operating pressure of the pressure transducer is 20 bar and calibrated with an accuracy of +-0.01 bar. High purity hydrogen is being used in the system and the amount of samples for the study is between 1.0-2.0 grams. The system was calibrated using helium gas without any samples in S1, S2 an S3. This will provide a correction factor during the adsorption process providing an adsorption free reference point when using hydrogen gas resulting in a more accurate reading of the adsorption process by eliminating the errors caused by temperature expansion effects and other non-adsorption related phenomena. The ideal gas equation of state is applied to calculate the hydrogen adsorption capacity based on the differential pressure measurements. Activated carbon with a surface area of 644.87 m{sup 2}/g showed a larger amount of adsorption as compared to multiwalled nanotubes (commercial) with a surface area of 119.68 m{sup 2}/g. This study als indicated that there is a direct correlation between the amounts of hydrogen adsorbed an surface area of the carbon materials under the conditions studied and that the

  5. Hydrogen Adsorption on Activated Carbon an Carbon Nanotubes Using Volumetric Differential Pressure Technique

    NASA Astrophysics Data System (ADS)

    Sanip, S. M.; Saidin, M. A. R.; Aziz, M.; Ismail, A. F.

    2010-03-01

    A simple hydrogen adsorption measurement system utilizing the volumetri differential pressure technique has been designed, fabricated and calibrated. Hydroge adsorption measurements have been carried out at temperatures 298 K and 77 K on activate carbon and carbon nanotubes with different surface areas. The adsorption data obtained will b helpful in understanding the adsorption property of the studied carbon materials using th fundamentals of adsorption theory. The principle of the system follows the Sievert-type metho The system measures a change in pressure between the reference cell, R1 and the sample cell S1, S2, S3 over a certain temperature range. R1, S1, S2, and S3 having known fixed volume The sample temperatures will be monitored by thermocouple TC while the pressures in R1 an S1, S2, S3 will be measured using a digital pressure transducer. The maximum operatin pressure of the pressure transducer is 20 bar and calibrated with an accuracy of ±0.01 bar. Hig purity hydrogen is being used in the system and the amount of samples for the study is betwee 1.0-2.0 grams. The system was calibrated using helium gas without any samples in S1, S2 an S3. This will provide a correction factor during the adsorption process providing an adsorption free reference point when using hydrogen gas resulting in a more accurate reading of th adsorption process by eliminating the errors caused by temperature expansion effects and oth non-adsorption related phenomena. The ideal gas equation of state is applied to calculate th hydrogen adsorption capacity based on the differential pressure measurements. Activated carbo with a surface area of 644.87 m2/g showed a larger amount of adsorption as compared to multiwalled nanotubes (commercial) with a surface area of 119.68 m2/g. This study als indicated that there is a direct correlation between the amounts of hydrogen adsorbed an surface area of the carbon materials under the conditions studied and that the adsorption significant at 77

  6. Air emission into a water shear layer through porous media. Part 2: Cavitation induced pressure attenuation

    SciTech Connect

    Myer, E.C.; Marboe, R.C.

    1994-12-31

    Cavitation near the casing of a hydroturbine can lead to damage through both cavitation erosion and mechanical vibration of the casing and the associated piping. Cavitation erosion results from the collapse of cavitation bubbles on or near a surface such as the casing wall. Mechanical vibrations transmitted to the casing directly through the collapse of bubbles on the casing wall indirectly through a coupling of the acoustic pressure pulse due to a nearby collapse on the turbine blade. Air emission along the casing can reduce the intensity of the tip vortex and the gap cavitation through ventilation of the cavity. Reduction in the machinery vibration is obtained by reduction of the intensity of cavitation bubble collapse and attenuation and scattering of the radiated acoustic pressure. This requires a bubble layer which may be introduced in the vicinity of the turbine blade tips. This layer remains for some distance downstream of the blades and is effective for attenuation of tip vortex induced noise and blade surface cavitation noise. For the purpose of characterizing this bubble layer within a water pipe, the authors spanned a pipe with a two dimensional hydrofoil and emitted air through porous media (20 and 100 micron porosity sintered stainless steel) into the shear flow over the hydrofoil. This paper is limited to an investigation of the attenuation of acoustic pressure propagating to the casing rather than the reduction in acoustic source level due to collapse cushioning effects.

  7. Differential analysis of camphor wood products by desorption atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Zhu, Liang; Yan, Jianping; Zhu, Zhiqiang; Ouyang, Yongzhong; Zhang, Xinglei; Zhang, Wenjun; Dai, Ximo; Luo, Liping; Chen, Huanwen

    2013-01-23

    In the course of this study, desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS) was applied to readily acquire the mass spectral fingerprints of camphor wood and other wood samples under ambient conditions. Characteristic natural analytes, such as camphor and geraniol, were successfully detected in their protonated form and then identified by tandem mass spectrometry (MS(n)). Further principal component analysis (PCA) and cluster analysis (CA) of the mass spectrometric results allow a confident discrimination of camphor wood products from inferior/fake ones. These experimental findings demonstrate that DAPCI-MS is a valuable tool for differential analysis of untreated camphor wood products with sufficient sensitivity and high throughput.

  8. Pressure Measurements Using an Airborne Differential Absorption Lidar. Part 1; Analysis of the Systematic Error Sources

    NASA Technical Reports Server (NTRS)

    Flamant, Cyrille N.; Schwemmer, Geary K.; Korb, C. Laurence; Evans, Keith D.; Palm, Stephen P.

    1999-01-01

    Remote airborne measurements of the vertical and horizontal structure of the atmospheric pressure field in the lower troposphere are made with an oxygen differential absorption lidar (DIAL). A detailed analysis of this measurement technique is provided which includes corrections for imprecise knowledge of the detector background level, the oxygen absorption fine parameters, and variations in the laser output energy. In addition, we analyze other possible sources of systematic errors including spectral effects related to aerosol and molecular scattering interference by rotational Raman scattering and interference by isotopic oxygen fines.

  9. Applications of high pressure differential scanning calorimetry to aviation fuel thermal stability research

    NASA Technical Reports Server (NTRS)

    Neveu, M. C.; Stocker, D. P.

    1985-01-01

    High pressure differential scanning calorimetry (DSC) was studied as an alternate method for performing high temperature fuel thermal stability research. The DSC was used to measure the heat of reaction versus temperature of a fuel sample heated at a programmed rate in an oxygen pressurized cell. Pure hydrocarbons and model fuels were studied using typical DSC operating conditions of 600 psig of oxygen and a temperature range from ambient to 500 C. The DSC oxidation onset temperature was determined and was used to rate the fuels on thermal stability. Kinetic rate constants were determined for the global initial oxidation reaction. Fuel deposit formation is measured, and the high temperature volatility of some tetralin deposits is studied by thermogravimetric analysis. Gas chromatography and mass spectrometry are used to study the chemical composition of some DSC stressed fuels.

  10. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hoseeinzadeh, Sepideh; Gorji-Bandpy, Mofid

    2012-04-01

    This paper presents a computational fluid dynamics (CFD) calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  11. Measurement of Respiration, Heart Beat and Body Movement on a Bed Using Dynamic Air-Pressure Sensor

    NASA Astrophysics Data System (ADS)

    Kuno, Hiroaki; Takashima, Mitsuru; Okawai, Hiroaki

    In this study, the possibility of the measurement of respiration, heart beat, and body movement on a bed was examined using the dynamic air-pressure sensor aiming at a daily health monitoring. The dynamic air-pressure sensor measures vital information using a change of air pressure. Twelve healthy volunteers participated in this study. The dynamic air-pressure sensor was installed under the bed mat and respiration and heart beat information were measured. This information was compared with the standard waveforms obtained from respiratory belt transducer and the electrocardiograph. As a result, both waveforms demonstrate a high correlation, and confirmed the validity of this method. A change of waveform and a quantitative evaluation of respiration, heart beat, and body movement measured from during sleep using this sensor can be useful for a daily health monitoring.

  12. High-pressure ceramic air heater for indirectly fired gas turbine applications

    NASA Astrophysics Data System (ADS)

    Lahaye, P. G.; Briggs, G. F.; Vandervort, C. L.; Seger, J. L.

    The Externally-Fired Combined Cycle (EFCC) offers a method for operating high-efficiency gas and steam turbine combined cycles on coal. In the EFCC, an air heater replaces the gas turbine combustor so that the turbine can be indirectly fired. Ceramic materials are required for the heat exchange surfaces to accommodate the operating temperatures of modern gas turbines. The ceramic air heater or heat exchanger is the focus of this program, and the two primary objectives are (1) to demonstrate that a ceramic air heater can be reliably pressurized to a level of 225 psia (1.5 MPa); and (2) to show that the air heater can withstand exposure to the products of coal combustion at elevated temperatures. By replacing the gas turbine combustor with a ceramic air heater, the cycle can use coal or other ash-bearing fuels. Numerous programs have attempted to fuel high efficiency gas turbines directly with coal, often resulting in significant ash deposition upon turbine components and corrosion or erosion of turbine blades. This report will show that a ceramic air heater is significantly less susceptible to ash deposition or corrosion than a gas turbine when protected by rudimentary methods of gas-stream clean-up. A 25 x 10(sup 6) Btu/hr (7 MW) test facility is under construction in Kennebunk, Maine. It is anticipated that this proof of concept program will lead to commercialization of the EFCC by electric utility and industrial organizations. Applications are being pursued for power plants ranging from 10 to 100 megawatts.

  13. Metal-air cells comprising collapsible foam members and means for minimizing internal pressure buildup

    NASA Technical Reports Server (NTRS)

    Woodruff, Glenn (Inventor); Putt, Ronald A. (Inventor)

    1994-01-01

    This invention provides a prismatic zinc-air cell including, in general, a prismatic container having therein an air cathode, a separator and a zinc anode. The container has one or more oxygen access openings, and the air cathode is disposed in the container in gaseous communication with the oxygen access openings so as to allow access of oxygen to the cathode. The separator has a first side in electrolytic communication with the air cathode and a second side in electrolytic communication with the zinc anode. The separator isolates the cathode and the zinc anode from direct electrical contact and allows passage of electrolyte therebetween. An expansion chamber adjacent to the zinc anode is provided which accommodates expansion of the zinc anode during discharge of the cell. A suitable collapsible foam member generally occupies the expansion space, providing sufficient resistance tending to oppose movement of the zinc anode away from the separator while collapsing upon expansion of the zinc anode during discharge of the cell. One or more vent openings disposed in the container are in gaseous communication with the expansion space, functioning to satisfactorily minimize the pressure buildup within the container by venting gasses expelled as the foam collapses during cell discharge.

  14. Study on an Efficient Dehumidifying Air-conditioning System utilizing Phase Change of Intermediate Pressure Refrigerant

    NASA Astrophysics Data System (ADS)

    Maeda, Kensaku; Inaba, Hideo

    The present study has proven a new dehumidifying system that aimed to reduce the sensible heat factor(SHF) of cooling process without using additional heat to relieve the internationally indicated conflict between energy saving and dehumidification necessary for keeping adequate indoor air quality (IAQ). In this system, we used intermediate pressure refrigerant in a vapor compression refrigerating cycle as heat transfer medium of a characteristic heat exchanger to precool the process air entering into an evaporator as well as to reheat the process air leaving from the evaporator. By this system, the present results achieved higher moisture removal and consequently higher efficiency of dehumidifying process. In addition to this fact, since this system has capability of integration into air-conditioning apparatus(HVAC system), it will be able to work for wide range of cooling load by variable SHF function. In the present paper, technical information, experimental results, and simulation results which assumed to apply this system into HVAC system are reported.

  15. Simulation of a runaway electron avalanche developing in an atmospheric pressure air discharge

    SciTech Connect

    Oreshkin, E. V.; Barengolts, S. A.; Chaikovsky, S. A.; Oreshkin, V. I.

    2015-12-15

    To gain a better understanding of the operation of atmospheric pressure air discharges, the formation of a runaway electron beam at an individual emission site on the cathode has been numerically simulated. The model provides a description of the dynamics of the fast electrons emitted into an air gap from the surface of the emission zone by solving numerically two-dimensional equations for the electrons. It is supposed that the electric field at the surface of the emission zone is enhanced, providing conditions for continuous acceleration of the emitted electrons. It is shown that the formation of a runaway electron beam in a highly overvolted discharge is largely associated with avalanche-type processes and that the number of electrons in the avalanche reaches 50% of the total number of runaway electrons.

  16. JT8D revised high-pressure turbine cooling and other outer air seal program

    NASA Technical Reports Server (NTRS)

    Gaffin, W. O.

    1979-01-01

    The JT8D high pressure turbine was revised to reduce leakage between the blade tip shrouds and the outer air seal, and engine testing was performed to determine the effect on performance. The addition of a second knife-edge on the blade tip shroud, the extension of the honeycomb seal land to cover the added knife-edge and an existing spoiler on the shroud, and a material substitution in the seal support ring to improve thermal growth characteristics are included. A relocation of the blade cooling air discharge to insure adequate cooling flow is required. Significant specific fuel consumption and exhaust gas temperature improvements were demonstrated with the revised turbine in sea level and simulated altitude engine tests. Inspection of the revised seal hardware after these tests showed no unusual wear or degradation.

  17. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro

    2014-12-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.

  18. BOREAS AFM-5 Level-2 Upper Air Network Standard Pressure Level Data

    NASA Technical Reports Server (NTRS)

    Barr, Alan; Hrynkiw, Charmaine; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The BOREAS AFM-5 team collected and processed data from the numerous radiosonde flights during the project. The goals of the AFM-05 team were to provide large-scale definition of the atmosphere by supplementing the existing AES aerological network, both temporally and spatially. This data set includes basic upper-air parameters interpolated at 0.5 kiloPascal increments of atmospheric pressure from data collected from the network of upper-air stations during the 1993, 1994, and 1996 field campaigns over the entire study region. The data are contained in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  19. A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

    SciTech Connect

    Liu, Wenzheng Sun, Guangliang Li, Chuanhui; Zhang, Rongrong

    2014-04-15

    Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

  20. Confronting environmental pressure, environmental quality and human health impact indicators of priority air emissions

    NASA Astrophysics Data System (ADS)

    Geelen, Loes M. J.; Huijbregts, Mark A. J.; den Hollander, Henri; Ragas, Ad M. J.; van Jaarsveld, Hans. A.; de Zwart, Dick

    This paper evaluates the ranking of 21 priority air pollutants with three indicator schemes: environmental pressure indicator (EPI), environmental quality indicator (EQI), and human health effect indicator (HEI). The EPI and EQI compare the emissions and concentrations with the target emissions and target concentrations, respectively. The HEI comprehends the steps from cause (i.e. national emissions) to effect (i.e. human health effects), and is the total human health burden, expressed in Disability Adjusted Life Years per year of exposure (DALYs year -1). We estimated a health burden in the Netherlands of 41 × 10 3 DALYs year -1 caused by Dutch air emissions of PM10 and its precursors in the year 2003. The burden due to 17 carcinogenic substances emitted to air, was much lower (140 DALYs year -1). In contrast, when the same substances were evaluated regarding environmental pressure and environmental quality, carbon tetrachloride (pressure) and benzo[ a]pyrene (quality) were of highest importance, whereas the importance of PM10 was substantially lower. This result is remarkable, because for the majority of substances evaluated, the target concentrations and target emissions are based on preventing human health damage. The differences in relevance are explained by the different weighting of interests in the indicators. The HEI is based on concentration-response relations, whereas the EPI and EQI also depend on other, policy-based, principles and on technical feasibility. Therefore, to effectively prioritize emission reduction measures in policy-making, substances should not only be evaluated as to whether emission targets and environmental quality targets are reached, but they should be evaluated regarding their human health impact as well. In this context, the HEI is a suitable indicator to evaluate the human health impact.

  1. Focused excimer laser initiated, radio frequency sustained high pressure air plasmas

    SciTech Connect

    Giar, Ryan; Scharer, John

    2011-11-15

    Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (n{sub e} {approx} 7 x 10{sup 16}/cm{sup 3}) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm{sup 2} at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

  2. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    PubMed Central

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W.; Jeong, Chang-Mo

    2013-01-01

    PURPOSE Autoclaves and UV sterilizers have been commonly used to prevent cross-infections between dental patients and dental instruments or materials contaminated by saliva and blood. To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated. MATERIALS AND METHODS After inoculating E. coli and B. subtilis the diamond burs and polyvinyl siloxane materials were sterilized by exposing them to the plasma for different lengths of time (30, 60, 90, 120, 180 and, 240 seconds). The diamond burs and polyvinyl siloxane materials were immersed in PBS solutions, cultured on agar plates and quantified by counting the colony forming units. The data were analyzed using one-way ANOVA and significance was assessed by the LSD post hoc test (α=0.05). RESULTS The device was effective in killing E. coli contained in the plasma device compared with the UV sterilizer. The atmospheric pressure non-thermal air plasma device contributed greatly to the sterilization of diamond burs and polyvinyl siloxane materials inoculated with E. coli and B. subtilis. Diamond burs and polyvinyl siloxane materials inoculated with E. coli was effective after 60 and 90 seconds. The diamond burs and polyvinyl siloxane materials inoculated with B. subtilis was effective after 120 and 180 seconds. CONCLUSION The atmospheric pressure non-thermal air plasma device was effective in killing both E. coli and B. subtilis, and was more effective in killing E. coli than the UV sterilizer. PMID:23508991

  3. High Precision Pressure Measurement with a Funnel

    ERIC Educational Resources Information Center

    Lopez-Arias, T.; Gratton, L. M.; Oss, S.

    2008-01-01

    A simple experimental device for high precision differential pressure measurements is presented. Its working mechanism recalls that of a hydraulic press, where pressure is supplied by insufflating air under a funnel. As an application, we measure air pressure inside a soap bubble. The soap bubble is inflated and connected to a funnel which is…

  4. Surface pressure-induced layer growth of a monolayer at the air-water interface

    SciTech Connect

    Fang, J.Y.; Uphaus, R.A. )

    1994-04-01

    Spread monolayers containing a nematic liquid crystal and stearic acid were characterized at various mole fractions by determination of surface pressure-area isotherms at the air-water interface. The surface-composition phase diagrams indicate that compression induces a new phase transition in the films, which changes from a mixed monolayer to a supermonomolecular system. X-ray diffraction and optical absorption spectra demonstrate that the supermolecular array consists of an island liquid crystal monolayer and a uniform stearic acid monolayer. 12 refs., 7 figs.

  5. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    SciTech Connect

    Narayan, Jagdish Bhaumik, Anagh

    2015-10-01

    We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals.

  6. Spectrum of the Runaway Electron Beam Generated During a Nanosecond Discharge in Air at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.

    2016-04-01

    The spectrum of supershort avalanche runaway electron beam generated in air at atmospheric pressure is experimentally investigated using a time-of-flight spectrometer and attenuation curves. It is shown that the maximum of the electron energy distribution for the main (second) group of electrons is less than the energy eUm, where Um is the maximal voltage across the gap, and the difference between these energies depends on the design of the cathode and the interelectrode gap in a gas diode. It is confirmed that there are three groups of electrons with different energies in the runaway electron beam spectrum.

  7. Scuba tanks as a compressed air source in positive-pressure ventilation.

    PubMed

    Stewart, T

    1992-06-01

    Throughout the developing world there is a general problem of ensuring regular deliveries of medical supplies to hospitals. This includes the supply of compressed gases. At one regional hospital in Vanuatu, we were faced with the problem of how to provide economically a source of compressed gas at regulated pressure to drive an anaesthetic ventilator. We eventually adapted the output from a Scuba cylinder for this purpose. This paper describes the simple modifications necessary and suggests other uses for this source of compressed air that could be implemented in hospitals with small to medium case loads and access to a diving compressor.

  8. Energy distribution of runaway electrons generated by a nanosecond discharge in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Kostyrya, I. D.; Lomaev, M. I.; Petin, V. K.; Rybka, D. V.; Shlyakhtun, S. V.

    2008-12-01

    The spectra of an ultrashort avalanche electron beam generated by a nanosecond discharge in atmospheric-pressure air were investigated. The temporal characteristics of the beam current pulses, gap voltage, and discharge current in a gas diode were measured with a time resolution of ˜0.1 ns. A simple technique was developed for recovering electron spectra from the curves of beam attenuation by aluminum foils. The effect of the cathode design, electrode gap length, and generator parameters on the electron spectra were studied using seven setups. It is shown that generation of electrons with anomalously high energies requires the use of cathodes with increased curvature radius.

  9. Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics†

    PubMed Central

    Fournier, Yannick; Maeder, Thomas; Boutinard-Rouelle, Grégoire; Barras, Aurélie; Craquelin, Nicolas; Ryser, Peter

    2010-01-01

    We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues. PMID:22163518

  10. Effects of ear-canal pressurization on middle-ear bone- and air-conduction responses

    PubMed Central

    Homma, Kenji; Shimizu, Yoshitaka; Kim, Namkeun; Du, Yu; Puria, Sunil

    2014-01-01

    In extremely loud noise environments, it is important to not only protect one’s hearing against noise transmitted through the air-conduction (AC) pathway, but also through the bone-conduction (BC) pathways. Much of the energy transmitted through the BC pathways is concentrated in the mid-frequency range around 1.5–2 kHz, which is likely due to the structural resonance of the middle ear. One potential approach for mitigating this mid-frequency BC noise transmission is to introduce a positive or negative static pressure in the ear canal, which is known to reduce BC as well as AC hearing sensitivity. In the present study, middle-ear ossicular velocities at the umbo and stapes were measured using human cadaver temporal bones in response to both BC and AC excitations, while static air pressures of ±400 mm H2O were applied in the ear canal. For the maximum negative pressure of −400 mm H2O, mean BC stapes-velocity reductions of about 5–8 dB were observed in the frequency range from 0.8 to 2.5 kHz, with a peak reduction of 8.6(± 4.7) dB at 1.6 kHz. Finite-element analysis indicates that the peak BC-response reduction tends to be in the mid-frequency range because the middle-ear BC resonance, which is typically around 1.5–2 kHz, is suppressed by the pressure-induced stiffening of the middle-ear structure. The measured data also show that the BC responses are reduced more for negative static pressures than for positive static pressures. This may be attributable to a difference in the distribution of the stiffening among the middle-ear components depending on the polarity of the static pressure. The characteristics of the BC-response reductions are found to be largely consistent with the available psychoacoustic data, and are therefore indicative of the relative importance of the middle-ear mechanism in BC hearing. PMID:19944139

  11. Effect of Fuel-Air Ratio, Inlet Temperature, and Exhaust Pressure on Detonation

    NASA Technical Reports Server (NTRS)

    Taylor, E S; Leary, W A; Diver, J R

    1940-01-01

    An accurate determination of the end-gas condition was attempted by applying a refined method of analysis to experimental results. The results are compared with those obtained in Technical Report no. 655. The experimental technique employed afforded excellent control over the engine variables and unusual cyclic reproducibility. This, in conjunction with the new analysis, made possible the determination of the state of the end-gas at any instant to a fair degree of precision. Results showed that for any given maximum pressure the maximum permissible end-gas temperature increased as the fuel-air ratio was increased. The tendency to detonate was slightly reduced by an increase in residual gas content resulting from an increase in exhaust backpressure with inlet pressure constant.

  12. Low-pressure reservoir drilled with air/N[sub 2] in a closed system

    SciTech Connect

    Teichrob, R.R. )

    1994-03-21

    Ignition tests on simulated produced fluids helped determine the ideal air/nitrogen mixture for an underbalanced drilling operation that used a closed surface system to process return fluids. The low-pressure, heavy-oil target reservoir required underbalanced drilling to minimize formation damage. Underbalanced or near-balanced drilling can improve production from pressure-depleted reservoirs by reducing the chance of formation damage from drilling fluid losses. Underbalanced drilling technology currently available includes the use of gas injection through parasite strings or through drilling tubulars. No one (to the author's knowledge) has combined concentric-string commingled gas injection with through-drilling-tubular commingled gas injection. The paper describes lab work, test results, surface returns, downhole design, operations, and field results.

  13. Porous graphene-based membranes for water purification from metal ions at low differential pressures

    NASA Astrophysics Data System (ADS)

    Park, Jaewoo; Bazylewski, Paul; Fanchini, Giovanni

    2016-05-01

    A new generation of membranes for water purification based on weakly oxidized and nanoporous few-layer graphene is here introduced. These membranes dramatically decrease the high energy requirements of water purification by reverse osmosis. They combine the advantages of porous and non-oxidized single-layer graphene, offering energy-efficient water filtration at relatively low differential pressures, and highly oxidized graphene oxide, exhibiting high performance in terms of impurity adsorption. In the reported fabrication process, leaks between juxtaposed few-layer graphene flakes are sealed by thermally annealed colloidal silica, in a treatment that precedes the opening of (sub)nanometre-size pores in graphene. This process, explored for the first time in this work, results in nanoporous graphene flakes that are water-tight at the edges without occluding the (sub)nanopores. With this method, removal of impurities from water occurs through a combination of size-based pore rejection and pore-edge adsorption. Thinness of graphene flakes allows these membranes to achieve water purification from metal ions in concentrations of few parts-per-million at differential pressures as low as 30 kPa, outperforming existing graphene or graphene oxide purification systems with comparable flow rates.

  14. Porous graphene-based membranes for water purification from metal ions at low differential pressures.

    PubMed

    Park, Jaewoo; Bazylewski, Paul; Fanchini, Giovanni

    2016-05-14

    A new generation of membranes for water purification based on weakly oxidized and nanoporous few-layer graphene is here introduced. These membranes dramatically decrease the high energy requirements of water purification by reverse osmosis. They combine the advantages of porous and non-oxidized single-layer graphene, offering energy-efficient water filtration at relatively low differential pressures, and highly oxidized graphene oxide, exhibiting high performance in terms of impurity adsorption. In the reported fabrication process, leaks between juxtaposed few-layer graphene flakes are sealed by thermally annealed colloidal silica, in a treatment that precedes the opening of (sub)nanometre-size pores in graphene. This process, explored for the first time in this work, results in nanoporous graphene flakes that are water-tight at the edges without occluding the (sub)nanopores. With this method, removal of impurities from water occurs through a combination of size-based pore rejection and pore-edge adsorption. Thinness of graphene flakes allows these membranes to achieve water purification from metal ions in concentrations of few parts-per-million at differential pressures as low as 30 kPa, outperforming existing graphene or graphene oxide purification systems with comparable flow rates. PMID:27098780

  15. Porous graphene-based membranes for water purification from metal ions at low differential pressures.

    PubMed

    Park, Jaewoo; Bazylewski, Paul; Fanchini, Giovanni

    2016-05-14

    A new generation of membranes for water purification based on weakly oxidized and nanoporous few-layer graphene is here introduced. These membranes dramatically decrease the high energy requirements of water purification by reverse osmosis. They combine the advantages of porous and non-oxidized single-layer graphene, offering energy-efficient water filtration at relatively low differential pressures, and highly oxidized graphene oxide, exhibiting high performance in terms of impurity adsorption. In the reported fabrication process, leaks between juxtaposed few-layer graphene flakes are sealed by thermally annealed colloidal silica, in a treatment that precedes the opening of (sub)nanometre-size pores in graphene. This process, explored for the first time in this work, results in nanoporous graphene flakes that are water-tight at the edges without occluding the (sub)nanopores. With this method, removal of impurities from water occurs through a combination of size-based pore rejection and pore-edge adsorption. Thinness of graphene flakes allows these membranes to achieve water purification from metal ions in concentrations of few parts-per-million at differential pressures as low as 30 kPa, outperforming existing graphene or graphene oxide purification systems with comparable flow rates.

  16. Aerosols generated by releases of pressurized powders and solutions in static air

    SciTech Connect

    Sutter, S.L.

    1983-08-01

    Safety assessments and environmental impact statements for nuclear fuel cycle facilities require an estimate of potential airborne releases caused by accidents. Aerosols generated by accidents are being investigated by Pacific Northwest Laboratory to develop the source terms for these releases. An upper boundary accidental release event would be a pressurized release of powder or liquid in static air. Experiments were run using various source sizes and pressures and measuring the mass airborne and the particle size distribution of aerosols produced by these pressurized releases. Two powder and two liquid sources were used: TiO/sub 2/ and depleted uranium dioxide (DUO); and aqueous uranine (sodium fluorescein) and uranyl nitrate solutions. Results of the experiments showed that pressurization level and source size were significant variables for the airborne powder releases. For this experimental configuration, the liquid releases were a function of pressure, but volume did not appear to be a significant variable. During the experiments 100 g and 350 g of DUO (1 ..mu..m dia) and TiO/sub 2/ (1.7 ..mu..m dia) powders and 100 cm/sup 3/ and 350 cm/sup 3/ of uranine and uranyl nitrate solutions were released at pressures ranging from 50 to 500 psig. The average of the largest fractions of powder airborne was about 24%. The maximum amount of liquid source airborne was significantly less, about 0.15%. The median aerodynamic equivalent diameters (AED) for collected airborne powders ranged from 5 to 19 ..mu..m; liquids ranged from 2 to 29 ..mu..m. All of the releases produced a significant fraction of respirable particles of 10 ..mu..m and less. 12 references, 10 figures, 23 tables.

  17. Laser-based measurements of OH in high pressure CH4/air flames

    NASA Technical Reports Server (NTRS)

    Battles, B. E.; Hanson, R. K.

    1991-01-01

    Narrow-linewidth laser absorption measurements are reported from which mole fraction and temperature of OH are determined in high-pressure (1-10 atm), lean CH4/air flames. These measurements were made in a new high pressure combustion facility which incorporates a traversable flat flame burner, providing spatially and temporally uniform combustion gases at pressures up to 10 am. A commercially avialable CW ring dye laser was used with an intracavity doubling crystal to provide near-UV single mode output at approximately 306 nm. The UV beam was rapidly scanned over 120 GHz (0.1 sec scan duration) to resolve the absorption lineshape of the A-X (0,0) R1(7)/R1(11) doublet of the OH radical. From the doublet's absorption lineshape, the temperature was determined; and from peak absorption, Beer's Law was employed to find the mole fraction of OH. These data were obtained as a function of height above the flame at various pressures.

  18. The lunar semidiurnal air pressure tide in in-situ data and ECMWF reanalyses

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Dobslaw, Henryk

    2016-04-01

    A gridded empirical model of the lunar semidiurnal air pressure tide L2 is deduced through multiquadric interpolation of more than 2000 globally distributed tidal estimates from land barometers and moored buoys. The resulting climatology serves as an independent standard to validate the barometric L2 oscillations that are present in ECMWF's (European Centre for Medium-Range Weather Forecasts) global atmospheric reanalyses despite the omission of gravitational forcing mechanisms in the involved forecast routines. Inconsistencies between numerical and empirical L2 solutions are found to be small even though the reanalysis models typically underestimate equatorial peak pressures by 10-20% and produce slightly deficient tidal phases in latitudes south of 30°N. Through using a time-invariant reference surface over both land and water and assimilating marine pressure data without accounting for vertical sensor movements due to the M2 ocean tide, ECMWF-based tidal solutions are also prone to strong local artifacts. Additionally, the dependency of the lunar tidal oscillation in atmospheric analysis systems on the meteorological input data is demonstrated based on a recent ECMWF twentieth-century reanalysis (ERA-20C) which draws its all of its observational constraints from in-situ registrations of pressure and surface winds. The L2 signature prior to 1950 is particularly indicative of distinct observing system changes, such as the paucity of marine data during both World Wars or the opening of the Panama Canal in 1914 and the associated adjustment of commercial shipping routes.

  19. Extreme Air Pollution Conditions Adversely Affect Blood Pressure and Insulin Resistance: The Air Pollution and Cardiometabolic Disease Study.

    PubMed

    Brook, Robert D; Sun, Zhichao; Brook, Jeffrey R; Zhao, Xiaoyi; Ruan, Yanping; Yan, Jianhua; Mukherjee, Bhramar; Rao, Xiaoquan; Duan, Fengkui; Sun, Lixian; Liang, Ruijuan; Lian, Hui; Zhang, Shuyang; Fang, Quan; Gu, Dongfeng; Sun, Qinghua; Fan, Zhongjie; Rajagopalan, Sanjay

    2016-01-01

    Mounting evidence supports that fine particulate matter adversely affects cardiometabolic diseases particularly in susceptible individuals; however, health effects induced by the extreme concentrations within megacities in Asia are not well described. We enrolled 65 nonsmoking adults with metabolic syndrome and insulin resistance in the Beijing metropolitan area into a panel study of 4 repeated visits across 4 seasons since 2012. Daily ambient fine particulate matter and personal black carbon levels ranged from 9.0 to 552.5 µg/m(3) and 0.2 to 24.5 µg/m(3), respectively, with extreme levels observed during January 2013. Cumulative fine particulate matter exposure windows across the prior 1 to 7 days were significantly associated with systolic blood pressure elevations ranging from 2.0 (95% confidence interval, 0.3-3.7) to 2.7 (0.6-4.8) mm Hg per SD increase (67.2 µg/m(3)), whereas cumulative black carbon exposure during the previous 2 to 5 days were significantly associated with ranges in elevations in diastolic blood pressure from 1.3 (0.0-2.5) to 1.7 (0.3-3.2) mm Hg per SD increase (3.6 µg/m(3)). Both black carbon and fine particulate matter were significantly associated with worsening insulin resistance (0.18 [0.01-0.36] and 0.22 [0.04-0.39] unit increase per SD increase of personal-level black carbon and 0.18 [0.02-0.34] and 0.22 [0.08-0.36] unit increase per SD increase of ambient fine particulate matter on lag days 4 and 5). These results provide important global public health warnings that air pollution may pose a risk to cardiometabolic health even at the extremely high concentrations faced by billions of people in the developing world today. PMID:26573709

  20. Extreme Air Pollution Conditions Adversely Affect Blood Pressure and Insulin Resistance: The Air Pollution and Cardiometabolic Disease Study.

    PubMed

    Brook, Robert D; Sun, Zhichao; Brook, Jeffrey R; Zhao, Xiaoyi; Ruan, Yanping; Yan, Jianhua; Mukherjee, Bhramar; Rao, Xiaoquan; Duan, Fengkui; Sun, Lixian; Liang, Ruijuan; Lian, Hui; Zhang, Shuyang; Fang, Quan; Gu, Dongfeng; Sun, Qinghua; Fan, Zhongjie; Rajagopalan, Sanjay

    2016-01-01

    Mounting evidence supports that fine particulate matter adversely affects cardiometabolic diseases particularly in susceptible individuals; however, health effects induced by the extreme concentrations within megacities in Asia are not well described. We enrolled 65 nonsmoking adults with metabolic syndrome and insulin resistance in the Beijing metropolitan area into a panel study of 4 repeated visits across 4 seasons since 2012. Daily ambient fine particulate matter and personal black carbon levels ranged from 9.0 to 552.5 µg/m(3) and 0.2 to 24.5 µg/m(3), respectively, with extreme levels observed during January 2013. Cumulative fine particulate matter exposure windows across the prior 1 to 7 days were significantly associated with systolic blood pressure elevations ranging from 2.0 (95% confidence interval, 0.3-3.7) to 2.7 (0.6-4.8) mm Hg per SD increase (67.2 µg/m(3)), whereas cumulative black carbon exposure during the previous 2 to 5 days were significantly associated with ranges in elevations in diastolic blood pressure from 1.3 (0.0-2.5) to 1.7 (0.3-3.2) mm Hg per SD increase (3.6 µg/m(3)). Both black carbon and fine particulate matter were significantly associated with worsening insulin resistance (0.18 [0.01-0.36] and 0.22 [0.04-0.39] unit increase per SD increase of personal-level black carbon and 0.18 [0.02-0.34] and 0.22 [0.08-0.36] unit increase per SD increase of ambient fine particulate matter on lag days 4 and 5). These results provide important global public health warnings that air pollution may pose a risk to cardiometabolic health even at the extremely high concentrations faced by billions of people in the developing world today.

  1. Novel Therapeutic Effects of Non-thermal atmospheric pressure plasma for Muscle Regeneration and Differentiation

    PubMed Central

    Choi, Jae Won; Kang, Sung Un; Kim, Yang Eun; Park, Ju Kyeong; Yang, Sang Sik; Kim, Yeon Soo; Lee, Yun Sang; Lee, Yuijina; Kim, Chul-Ho

    2016-01-01

    Skeletal muscle can repair muscle tissue damage, but significant loss of muscle tissue or its long-lasting chronic degeneration makes injured skeletal muscle tissue difficult to restore. It has been demonstrated that non-thermal atmospheric pressure plasma (NTP) can be used in many biological areas including regenerative medicine. Therefore, we determined whether NTP, as a non-contact biological external stimulator that generates biological catalyzers, can induce regeneration of injured muscle without biomaterials. Treatment with NTP in the defected muscle of a Sprague Dawley (SD) rat increased the number of proliferating muscle cells 7 days after plasma treatment (dapt) and rapidly induced formation of muscle tissue and muscle cell differentiation at 14 dapt. In addition, in vitro experiments also showed that NTP could induce muscle cell proliferation and differentiation of human muscle cells. Taken together, our results demonstrated that NTP promotes restoration of muscle defects through control of cell proliferation and differentiation without biological or structural supporters, suggesting that NTP has the potential for use in muscle tissue engineering and regenerative therapies. PMID:27349181

  2. Differential pressure measurement using a free-flying insect-like ornithopter with an MEMS sensor.

    PubMed

    Takahashi, Hidetoshi; Aoyama, Yuichiro; Ohsawa, Kazuharu; Tanaka, Hiroto; Iwase, Eiji; Matsumoto, Kiyoshi; Shimoyama, Isao

    2010-09-01

    This paper presents direct measurements of the aerodynamic forces on the wing of a free-flying, insect-like ornithopter that was modeled on a hawk moth (Manduca sexta). A micro differential pressure sensor was fabricated with micro electro mechanical systems (MEMS) technology and attached to the wing of the ornithopter. The sensor chip was less than 0.1% of the wing area. The mass of the sensor chip was 2.0 mg, which was less than 1% of the wing mass. Thus, the sensor was both small and light in comparison with the wing, resulting in a measurement system that had a minimal impact on the aerodynamics of the wing. With this sensor, the 'pressure coefficient' of the ornithopter wing was measured during both steady airflow and actual free flight. The maximum pressure coefficient observed for steady airflow conditions was 1.4 at an angle of attack of 30 degrees . In flapping flight, the coefficient was around 2.0 for angles of attack that ranged from 25 degrees to 40 degrees . Therefore, a larger aerodynamic force was generated during the downstroke in free flight compared to steady airflow conditions. PMID:20710069

  3. Integrated Energy Method for Propulsion Dynamics Analysis of Air-Pressurized Waterjet Rocket

    NASA Astrophysics Data System (ADS)

    Lee, Hsing-Juin; Chiu, Chih-Hong; Hsia, Wen-Kung

    The launching of a waterjet rocket has been a very popular idea in recent years. Its basic propulsion principle makes use of the high-pressurized air inside the rocket’s main body to swiftly expel the water out of the nozzle and thus generate thrust. The waterjet rocket is characterized with nature, interest, combustionlessness, environmental friendliness, simplicity, and minimal cost. Moreover, it is a very good science model for propulsion analysis, design, experiment, and education because of an abundance of easily adjustable key parameters. This model also features separately stored energy and mass of the propellant, in contrast to a conventional rocket. However, related literature shows that no in-depth theoretical analysis of the waterjet rocket has been attempted for various reasons. In this research, the propulsion dynamics of a waterjet rocket is analyzed by simultaneously solving the momentum and the newly derived generalized power equations to predict its flight histogram, computationally, and convolutionally. This integrated energy approach synthesizes the internal and external dynamics analyses together and ingeniously takes full advantage of the clear power supply of pressurized air in a waterjet rocket. The analysis results are generally agreeable with the experimental flight data. While the new power equation herein gives a complete spectrum of physical parameters to be manipulated, there will be wider room in quest of better rocket propulsion performance, especially through the heuristic research of this versatile but affordable waterjet rocket.

  4. Emission spectroscopy of an atmospheric pressure plasma jet operated with air at low frequency

    NASA Astrophysics Data System (ADS)

    Giuliani, L.; Gallego, J. L.; Minotti, F.; Kelly, H.; Grondona, D.

    2015-03-01

    Low-temperature, high-pressure plasma jets have an extensive use in plasma biology and plasma medicine, such as pathogen deactivation, wound disinfection, stopping of bleeding without damage of healthy tissue, acceleration of wound healing, control of bio-film proliferation, etc. In this work, a spectroscopic characterization of a typical plasma jet, operated in air at atmospheric pressure, is reported. Within the spectrum of wavelengths from 200 to 450 nm all remarkable emissions of N2 were monitored. Spectra of the N2 2nd positive system (C3Πu-B3Πg) emitted in air are the most convenient for plasma diagnostics, since they enable to determine electronic Te, rotational Tr and vibrational Tv temperatures by fitting the experimental spectra with the simulated ones. We used SPECAIR software for spectral simulation and obtained the best fit with all these temperatures about 3500K. The conclusion that all temperatures are equal, and its relatively high value, is consistent with the results of a previous work, where it was found that the experimentally determined electrical characteristic was consistent with the model of a thermal arc discharge, together with a highly collisional cathode sheet.

  5. Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

    NASA Technical Reports Server (NTRS)

    Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

    2003-01-01

    Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were

  6. Aire regulates the expression of differentiation-associated genes and self-renewal of embryonic stem cells.

    PubMed

    Gu, Bin; Zhang, Jiarong; Chen, Qi; Tao, Bo; Wang, Wei; Zhou, Yang; Chen, Liangbiao; Liu, Yusen; Zhang, Ming

    2010-04-01

    Embryonic stem cells (ESCs) are pluripotent stem cells from early embryos. It has been well recognized that ESC genomes are maintained in a globally transcriptional hyperactive state, which genetically poised ESCs to the high differentiation potential. However, the transcription factors regulating the global transcription activities in ESCs are not well defined. We show here that mouse and human ESCs express two transcription factors, Aire and Deaf1. Previously known to function in the thymus stromal cells and peripheral lymphoid organs respectively, Aire and Deaf1 help regulate the ectopic expression of diverse tissue-specific antigens to establish self-immune tolerance. Differentiation of ESCs greatly reduced Aire and Deaf1 expression, in a pattern similar to the pluripotent factors, Oct4 and Nanog. Knockdown of Aire in mouse ESCs resulted in significantly decreased clone-forming efficiency as well as attenuated cell cycle, suggesting Aire plays a role in ESC self-renewal. In addition, some differentiation-associated genes that are sporadically expressed in ESCs were reduced in expression upon Aire knockdown. These results suggest that transcription factors such as Aire and Deaf1, which exert global transcriptional regulatory functions, may play important roles in self-renewal of ESCs and maintaining ESC in a transcriptionally hyperactive state.

  7. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Liu, Xinghua; Xian, Richang; Sun, Xuefeng; Wang, Tao; Lv, Xuebin; Chen, Suhong; Yang, Fan

    2014-08-01

    Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and continuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agreement with experimental measurements. The behavior of the electronic avalanche progress is also described. O2+ and N2+ are the dominant positive ions, and the values of O- and O2- densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system.

  8. Use of MODIS Cloud Top Pressure to Improve Assimilation Yields of AIRS Radiances in GSI

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi

    2014-01-01

    Radiances from hyperspectral sounders such as the Atmospheric Infrared Sounder (AIRS) are routinely assimilated both globally and regionally in operational numerical weather prediction (NWP) systems using the Gridpoint Statistical Interpolation (GSI) data assimilation system. However, only thinned, cloud-free radiances from a 281-channel subset are used, so the overall percentage of these observations that are assimilated is somewhere on the order of 5%. Cloud checks are performed within GSI to determine which channels peak above cloud top; inaccuracies may lead to less assimilated radiances or introduction of biases from cloud-contaminated radiances.Relatively large footprint from AIRS may not optimally represent small-scale cloud features that might be better resolved by higher-resolution imagers like the Moderate Resolution Imaging Spectroradiometer (MODIS). Objective of this project is to "swap" the MODIS-derived cloud top pressure (CTP) for that designated by the AIRS-only quality control within GSI to test the hypothesis that better representation of cloud features will result in higher assimilated radiance yields and improved forecasts.

  9. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2016-02-01

    Non-thermal atmospheric pressure plasmas have been applied in the biomedical field for the improvement of various cellular activities. In dentistry, the healing of gingival soft tissue plays an important role in health and aesthetic outcomes. While the biomedical application of plasma has been thoroughly studied in dentistry, a detailed investigation of plasma-mediated human gingival fibroblast (HGF) migration for wound healing and its underlying biological mechanism is still pending. Therefore, the aim of this study is to apply a non-thermal air atmospheric pressure plasma jet (NTAAPPJ) to HGF to measure the migration and to reveal the underlying biological mechanisms involved in the migration. After the characterization of NTAAPPJ by optical emission spectroscopy, the adherent HGF was treated with NTAAPPJ or air with a different flow rate. Cell viability, lipid peroxidation, migration, intracellular reactive oxygen species (ROS), and the expression of migration-related genes (EGFR, PAK1, and MAPK3) were investigated. The level of statistical significance was set at 0.05. NTAAPPJ and air treatment with a flow rate of 250–1000 standard cubic centimetres per minute (sccm) for up to 30 s did not induce significant decreases in cell viability or membrane damage. A significant increase in the migration of mitomycin C-treated HGF was observed after 30 s of NTAAPPJ treatment compared to 30 s air-only treatment, which was induced by high levels of intracellular reactive oxygen species (ROS). An increase in migration-related gene expression and EGFR activation was observed following NTAAPPJ treatment in an air flow rate-dependent manner. This is the first report that NTAAPPJ treatment induces an increase in HGF migration without changing cell viability or causing membrane damage. HGF migration was related to an increase in intracellular ROS, changes in the expression of three of the migration-related genes (EGFR, PAK1, and MAPK1), and EGFR activation. Therefore

  10. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2016-02-01

    Non-thermal atmospheric pressure plasmas have been applied in the biomedical field for the improvement of various cellular activities. In dentistry, the healing of gingival soft tissue plays an important role in health and aesthetic outcomes. While the biomedical application of plasma has been thoroughly studied in dentistry, a detailed investigation of plasma-mediated human gingival fibroblast (HGF) migration for wound healing and its underlying biological mechanism is still pending. Therefore, the aim of this study is to apply a non-thermal air atmospheric pressure plasma jet (NTAAPPJ) to HGF to measure the migration and to reveal the underlying biological mechanisms involved in the migration. After the characterization of NTAAPPJ by optical emission spectroscopy, the adherent HGF was treated with NTAAPPJ or air with a different flow rate. Cell viability, lipid peroxidation, migration, intracellular reactive oxygen species (ROS), and the expression of migration-related genes (EGFR, PAK1, and MAPK3) were investigated. The level of statistical significance was set at 0.05. NTAAPPJ and air treatment with a flow rate of 250-1000 standard cubic centimetres per minute (sccm) for up to 30 s did not induce significant decreases in cell viability or membrane damage. A significant increase in the migration of mitomycin C-treated HGF was observed after 30 s of NTAAPPJ treatment compared to 30 s air-only treatment, which was induced by high levels of intracellular reactive oxygen species (ROS). An increase in migration-related gene expression and EGFR activation was observed following NTAAPPJ treatment in an air flow rate-dependent manner. This is the first report that NTAAPPJ treatment induces an increase in HGF migration without changing cell viability or causing membrane damage. HGF migration was related to an increase in intracellular ROS, changes in the expression of three of the migration-related genes (EGFR, PAK1, and MAPK1), and EGFR activation. Therefore

  11. Air Pollution from Industrial Swine Operations and Blood Pressure of Neighboring Residents

    PubMed Central

    Horton, Rachel Avery; Rose, Kathryn M.

    2012-01-01

    Background: Industrial swine operations emit odorant chemicals including ammonia, hydrogen sulfide (H2S), and volatile organic compounds. Malodor and pollutant concentrations have been associated with self-reported stress and altered mood in prior studies. Objectives: We conducted a repeated-measures study of air pollution, stress, and blood pressure in neighbors of swine operations. Methods: For approximately 2 weeks, 101 nonsmoking adult volunteers living near industrial swine operations in 16 neighborhoods in eastern North Carolina sat outdoors for 10 min twice daily at preselected times. Afterward, they reported levels of hog odor on a 9-point scale and measured their blood pressure twice using an automated oscillometric device. During the same 2- to 3-week period, we measured ambient levels of H2S and PM10 at a central location in each neighborhood. Associations between systolic and diastolic blood pressure (SBP and DBP, respectively) and pollutant measures were estimated using fixed-effects (conditional) linear regression with adjustment for time of day. Results: PM10 showed little association with blood pressure. DBP [β (SE)] increased 0.23 (0.08) mmHg per unit of reported hog odor during the 10 min outdoors and 0.12 (0.08) mmHg per 1-ppb increase of H2S concentration in the same hour. SBP increased 0.10 (0.12) mmHg per odor unit and 0.29 (0.12) mmHg per 1-ppb increase of H2S in the same hour. Reported stress was strongly associated with BP; adjustment for stress reduced the odor–DBP association, but the H2S–SBP association changed little. Conclusions: Like noise and other repetitive environmental stressors, malodors may be associated with acute blood pressure increases that could contribute to development of chronic hypertension. PMID:23111006

  12. Electron density measurements in an atmospheric pressure air plasma by means of infrared heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Leipold, Frank; Stark, Robert H.; El-Habachi, Ahmed; Schoenbach, Karl H.

    2000-09-01

    An infrared heterodyne interferometer has been used to measure the spatial distribution of the electron density in direct current, atmospheric pressure discharges in air. Spatial resolution of the electron density in the high-pressure glow discharge with characteristic dimensions on the order of 100 µm required the use of a CO2 laser at a wavelength of 10.6 µm. For this wavelength and electron densities greater than 1011 cm-3 the index of refraction of the atmospheric air plasma is mainly determined by heavy particles rather than electrons. The electron contribution to the refractive index was separated from that of the heavy particles by taking the different relaxation times of the two particle species into account. With the discharge operated in a repetitive pulsed mode, the initial rapid change of the refractive index was assumed to be due to the increase in electron density, whereas the following slower rise is due to the decrease in gas density caused by gas heating. By reducing the time between pulses, direct current conditions were approached, and the electron density as well as the gas density, and gas temperature, respectively, were obtained through extrapolation. A computation inversion method was used to determine the radial distribution of the plasma parameters in the cylindrical discharge. For a direct-current filamentary discharge in air, at a current of 10 mA, the electron density was found to be 1013 cm-3 in the centre, decreasing to half of this value at a radial distance of 0.21 mm. Gaussian temperature profiles with σ = 1.1 mm and maximum values of 1000-2000 K in the centre were also obtained with, however, larger error margins than for electron densities.

  13. Road, rail, and air transportation noise in residential and workplace neighborhoods and blood pressure (RECORD Study).

    PubMed

    Méline, Julie; Van Hulst, Andraea; Thomas, Frederique; Chaix, Basile

    2015-01-01

    Associations between road traffic noise and hypertension have been repeatedly documented, whereas associations with rail or total road, rail, and air (RRA) traffic noise have rarely been investigated. Moreover, most studies of noise in the environment have only taken into account the residential neighborhood. Finally, few studies have taken into account individual/neighborhood confounders in the relationship between noise and hypertension. We performed adjusted multilevel regression analyses using data from the 7,290 participants of the RECORD Study to investigate the associations of outdoor road, rail, air, and RRA traffic noise estimated at the place of residence, at the workplace, and in the neighborhoods around the residence and workplace with systolic blood pressure (SBP), diastolic blood pressure (DBP), and hypertension. Associations were documented between higher outdoor RRA and road traffic noise estimated at the workplace and a higher SBP [+1.36 mm of mercury, 95% confidence interval (CI): +0.12, +2.60 for 65-80 dB(A) vs 30-45 dB(A)] and DBP [+1.07 (95% CI: +0.28, +1.86)], after adjustment for individual/neighborhood confounders. These associations remained after adjustment for risk factors of hypertension. Associations were documented neither with rail traffic noise nor for hypertension. Associations between transportation noise at the workplace and blood pressure (BP) may be attributable to the higher levels of road traffic noise at the workplace than at the residence. To better understand why only noise estimated at the workplace was associated with BP, our future work will combine Global Positioning System (GPS) tracking, assessment of noise levels with sensors, and ambulatory monitoring of BP. PMID:26356373

  14. Road, rail, and air transportation noise in residential and workplace neighborhoods and blood pressure (RECORD Study)

    PubMed Central

    Méline, Julie; Van Hulst, Andraea; Thomas, Frederique; Chaix, Basile

    2015-01-01

    Associations between road traffic noise and hypertension have been repeatedly documented, whereas associations with rail or total road, rail, and air (RRA) traffic noise have rarely been investigated. Moreover, most studies of noise in the environment have only taken into account the residential neighborhood. Finally, few studies have taken into account individual/neighborhood confounders in the relationship between noise and hypertension. We performed adjusted multilevel regression analyses using data from the 7,290 participants of the RECORD Study to investigate the associations of outdoor road, rail, air, and RRA traffic noise estimated at the place of residence, at the workplace, and in the neighborhoods around the residence and workplace with systolic blood pressure (SBP), diastolic blood pressure (DBP), and hypertension. Associations were documented between higher outdoor RRA and road traffic noise estimated at the workplace and a higher SBP [+1.36 mm of mercury, 95% confidence interval (CI): +0.12, +2.60 for 65-80 dB(A) vs 30-45 dB(A)] and DBP [+1.07 (95% CI: +0.28, +1.86)], after adjustment for individual/neighborhood confounders. These associations remained after adjustment for risk factors of hypertension. Associations were documented neither with rail traffic noise nor for hypertension. Associations between transportation noise at the workplace and blood pressure (BP) may be attributable to the higher levels of road traffic noise at the workplace than at the residence. To better understand why only noise estimated at the workplace was associated with BP, our future work will combine Global Positioning System (GPS) tracking, assessment of noise levels with sensors, and ambulatory monitoring of BP. PMID:26356373

  15. Microwave air plasmas in capillaries at low pressure I. Self-consistent modeling

    NASA Astrophysics Data System (ADS)

    Coche, P.; Guerra, V.; Alves, L. L.

    2016-06-01

    This work presents the self-consistent modeling of micro-plasmas generated in dry air using microwaves (2.45 GHz excitation frequency), within capillaries (<1 mm inner radius) at low pressure (300 Pa). The model couples the system of rate balance equations for the most relevant neutral and charged species of the plasma to the homogeneous electron Boltzmann equation. The maintenance electric field is self-consistently calculated adopting a transport theory for low to intermediate pressures, taking into account the presence of O- ions in addition to several positive ions, the dominant species being O{}2+ , NO+ and O+ . The low-pressure small-radius conditions considered yield very-intense reduced electric fields (˜600-1500 Td), coherent with species losses controlled by transport and wall recombination, and kinetic mechanisms strongly dependent on electron-impact collisions. The charged-particle transport losses are strongly influenced by the presence of the negative ion, despite its low-density (˜10% of the electron density). For electron densities in the range (1-≤ft. 4\\right)× {{10}12} cm-3, the system exhibits high dissociation degrees for O2 (˜20-70%, depending on the working conditions, in contrast with the  ˜0.1% dissociation obtained for N2), a high concentration of O2(a) (˜1014 cm-3) and NO(X) (5× {{10}14} cm-3) and low ozone production (<{{10}-3}% ).

  16. Air Pollution Exposure and Blood Pressure: An Updated Review of the Literature.

    PubMed

    Giorgini, Paolo; Di Giosia, Paolo; Grassi, Davide; Rubenfire, Melvyn; Brook, Robert D; Ferri, Claudio

    2016-01-01

    Both high arterial blood pressure (BP) and elevated levels of fine particulate matter (PM2.5) air pollution have been associated with an increased risk for several cardiovascular (CV) diseases, including stroke, heart failure, and myocardial infarction. Given that PM2.5 and high BP are each independently leading risk factors for premature mortality worldwide, a potential relationship between these factors would have tremendous public health repercussions. Therefore, the aim of this review is to summarize recent evidence linking air pollution and BP. Epidemiological findings demonstrate that particulate pollutants cause significant increases in BP parameters in relation to both short and long-term exposures, with robust evidence for exposures to PM2.5. Moreover, recent epidemiological studies suggest a positive association between residence within regions with higher levels of ambient PM and an increased incidence and prevalence of overt hypertension. Studies provide consistent results that elevated concentrations of pollutants increase hospital admissions and/or emergency visits for hypertensive disorders and also support that PM levels increases BP in vulnerable subsets of individuals (pregnant women, high CV risk individuals). In this context, PM-mediated BP elevations may be an important pathway which acts as a potential triggering factor for acute CV events. Mechanistic evidence illustrates plausible pathways by which acute and chronic exposures to air pollutants might disrupt hemodynamic balance favoring vasoconstriction, including autonomic imbalance and augmented release of various pro-oxidative, inflammatory and/or hemodynamically-active mediators. Together these responses may underlie PM-induced BP elevations; however, full details regarding the responsible mechanisms require further studies. As a consequence of the ubiquity of air pollution, even a small effect on raising BP and/or the prevalence of hypertension, i.e. the major risk factor for mortality

  17. Atmospheric pressure resistive barrier air plasma jet induced bacterial inactivation in aqueous environment

    NASA Astrophysics Data System (ADS)

    Thiyagarajan, Magesh; Sarani, Abdollah; Gonzales, Xavier

    2013-03-01

    An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in aqueous media in direct and indirect exposure modes of treatment. The resistive barrier plasma jet is designed to operate at both dc and standard 50-60 Hz low frequency ac power input and the ambient air at 50% humidity level was used as the operating gas. The voltage-current characteristics of the plasma jet were analyzed and the operating frequency of the discharge was measured to be 20 kHz and the plasma power was measured to be 26 W. The plasma jet rotational temperatures (Trot) are obtained from the optical emission spectra, from the N2C-B(2+) transitions by matching the experimental spectrum results with the Spectra Air (SPECAIR) simulation spectra. The reactive oxygen and nitrogen species were measured using optical emission spectroscopy and gas analyzers, for direct and indirect treatment modes. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Neisseria meningitidis (Gram-negative) were suspended in an aqueous media and treated by the resistive barrier air plasma jet in direct and indirect exposure modes. The results show that a near complete bacterial inactivation was achieved within 120 s for both direct and indirect plasma treatment of S. aureus and E. coli bacteria. Conversely, a partial inactivation of N. meningitidis was observed by 120 s direct plasma exposure and insignificant inactivation was observed for the indirect plasma exposure treatment. Plasma induced shifts in N. meningitidis gene expression was analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.

  18. A New Differential Pressure Flow Meter for Measurement of Human Breath Flow: Simulation and Experimental Investigation

    PubMed Central

    Bridgeman, Devon; Tsow, Francis; Xian, Xiaojun; Forzani, Erica

    2016-01-01

    The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a “Confined Pitot Tube,” is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method.

  19. Differential Features of AIRE-Induced and AIRE-Independent Promiscuous Gene Expression in Thymic Epithelial Cells.

    PubMed

    St-Pierre, Charles; Trofimov, Assya; Brochu, Sylvie; Lemieux, Sébastien; Perreault, Claude

    2015-07-15

    Establishment of self-tolerance in the thymus depends on promiscuous expression of tissue-restricted Ags (TRA) by thymic epithelial cells (TEC). This promiscuous gene expression (pGE) is regulated in part by the autoimmune regulator (AIRE). To evaluate the commonalities and discrepancies between AIRE-dependent and -independent pGE, we analyzed the transcriptome of the three main TEC subsets in wild-type and Aire knockout mice. We found that the impact of AIRE-dependent pGE is not limited to generation of TRA. AIRE decreases, via non-cell autonomous mechanisms, the expression of genes coding for positive regulators of cell proliferation, and it thereby reduces the number of cortical TEC. In mature medullary TEC, AIRE-driven pGE upregulates non-TRA coding genes that enhance cell-cell interactions (e.g., claudins, integrins, and selectins) and are probably of prime relevance to tolerance induction. We also found that AIRE-dependent and -independent TRA present several distinctive features. In particular, relative to AIRE-induced TRA, AIRE-independent TRA are more numerous and show greater splicing complexity. Furthermore, we report that AIRE-dependent versus -independent TRA project nonredundant representations of peripheral tissues in the thymus.

  20. Rate of water equilibration in vapor-diffusion crystallization: dependence on the residual pressure of air in the vapor space.

    PubMed

    DeTitta, G T; Luft, J R

    1995-09-01

    The kinetics of water equilibration in vapor-diffusion crystallization experiments are sensitive to the residual pressure of air in the vapor chamber. Experiments with sitting droplets of 10%(w/v) PEG, allowed to equilibrate with reservoirs of 20%(w/v) PEG, were conducted at pressures ranging from 80 to 760 mm Hg. Equilibrations were interrupted after one, four, five and seven days to assess their progress. Even down to the lowest pressures examined it was found that a decrease in pressure leads to an increase in the rate of equilibration. The residual pressure of air in the vapor chamber can be varied to tailor the time course of equilibration in macromolecular crystal growth experiments.

  1. A global ground truth view of the lunar air pressure tide L2

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Dobslaw, Henryk

    2016-01-01

    A comprehensive model of the lunar air pressure tide L2 is developed on the basis of 2315 ground truth estimates from land barometers and moored buoys. Regional-scale features of the tide and its seasonal modulations are well resolved by the in situ scatter and gridded to a 2° mesh through multiquadric interpolation. The resulting climatologies serve as an independent standard to validate the lunar semidiurnal tidal signal that is present in ERA-Interim reanalysis products despite the absence of L2-related gravitational forcing mechanisms in the prescribed model physics. Inconsistencies between the reanalysis solution of the barometric lunar tide and its empirical account are generally small, yet when averaged over the period 1979-2010, ERA-Interim underestimates the 100 μbar open ocean tidal amplitude in the Tropics by up to 20 μbar and produces times of peak pressure that are too early by 10 lunar minutes. Large-amplitude features of the reanalysis tide off the coast of Alaska, the eastern U.S., and Great Britain are evidently spurious, introduced to the analysis system by assimilating marine pressure data at an invariant reference surface instead of properly accounting for vertical sensor movements associated with the M2 ocean tide. Additionally, a credible L2 signal is documented for the ERA-20C pilot reanalysis of the twentieth century. The fact that this model rests upon input data from mere surface observations provides an unambiguous indication that the lunar tidal oscillation in atmospheric analysis systems is closely tied to the assimilation of conventional pressure measurements from stations and marine objects.

  2. Differential Post-Exercise Blood Pressure Responses between Blacks and Caucasians

    PubMed Central

    Yan, Huimin; Behun, Michael A.; Cook, Marc D.; Ranadive, Sushant M.; Lane-Cordova, Abbi D.; Kappus, Rebecca M.; Woods, Jeffrey A.; Wilund, Kenneth R.; Baynard, Tracy; Halliwill, John R.; Fernhall, Bo

    2016-01-01

    Post-exercise hypotension (PEH) is widely observed in Caucasians (CA) and is associated with histamine receptors 1- and 2- (H1R and H2R) mediated post-exercise vasodilation. However, it appears that blacks (BL) may not exhibit PEH following aerobic exercise. Hence, this study sought to determine the extent to which BL develop PEH, and the contribution of histamine receptors to PEH (or lack thereof) in this population. Forty-nine (22 BL, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either a combined H1R and H2R antagonist (fexofenadine and ranitidine) or a control placebo. Supine blood pressure (BP), cardiac output and peripheral vascular resistance measurements were obtained at baseline, as well as at 30 min, 60 min and 90 min after 45 min of treadmill exercise at 70% heart rate reserve. Exercise increased diastolic BP in young BL but not in CA. Post-exercise diastolic BP was also elevated in BL after exercise with histamine receptor blockade. Moreover, H1R and H2R blockade elicited differential responses in stroke volume between BL and CA at rest, and the difference remained following exercise. Our findings show differential BP responses following exercise in BL and CA, and a potential role of histamine receptors in mediating basal and post-exercise stroke volume in BL. The heightened BP and vascular responses to exercise stimulus is consistent with the greater CVD risk in BL. PMID:27074034

  3. Differential Post-Exercise Blood Pressure Responses between Blacks and Caucasians.

    PubMed

    Yan, Huimin; Behun, Michael A; Cook, Marc D; Ranadive, Sushant M; Lane-Cordova, Abbi D; Kappus, Rebecca M; Woods, Jeffrey A; Wilund, Kenneth R; Baynard, Tracy; Halliwill, John R; Fernhall, Bo

    2016-01-01

    Post-exercise hypotension (PEH) is widely observed in Caucasians (CA) and is associated with histamine receptors 1- and 2- (H1R and H2R) mediated post-exercise vasodilation. However, it appears that blacks (BL) may not exhibit PEH following aerobic exercise. Hence, this study sought to determine the extent to which BL develop PEH, and the contribution of histamine receptors to PEH (or lack thereof) in this population. Forty-nine (22 BL, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either a combined H1R and H2R antagonist (fexofenadine and ranitidine) or a control placebo. Supine blood pressure (BP), cardiac output and peripheral vascular resistance measurements were obtained at baseline, as well as at 30 min, 60 min and 90 min after 45 min of treadmill exercise at 70% heart rate reserve. Exercise increased diastolic BP in young BL but not in CA. Post-exercise diastolic BP was also elevated in BL after exercise with histamine receptor blockade. Moreover, H1R and H2R blockade elicited differential responses in stroke volume between BL and CA at rest, and the difference remained following exercise. Our findings show differential BP responses following exercise in BL and CA, and a potential role of histamine receptors in mediating basal and post-exercise stroke volume in BL. The heightened BP and vascular responses to exercise stimulus is consistent with the greater CVD risk in BL. PMID:27074034

  4. Modeling the chemical kinetics of high-pressure glow discharges in mixtures of helium with real air

    SciTech Connect

    Stalder, K.R.; Vidmar, R.J.; Nersisyan, G.; Graham, W.G.

    2006-05-01

    Atmospheric and near-atmospheric pressure glow discharges generated in both pure helium and helium-air mixtures have been studied using a plasma chemistry code originally developed for simulations of electron-beam-produced air plasmas. Comparisons are made with experimental data obtained from high-pressure glow discharges in helium-air mixtures developed by applying sinusoidal voltage wave forms between two parallel planar metallic electrodes covered by glass plates, with frequencies ranging from 10 to 50 kHz and electric field strengths up to 5 kV/cm. The code simulates the plasma chemistry following periodic pulsations of ionization in prescribed E/N environments. Many of the rate constants depend on gas temperature, electron temperature, and E/N. In helium plasmas with small amounts ({approx}850 ppm) of air added, rapid conversion of atomic helium ions to molecular helium ions dominate the positive ion kinetics and these species are strongly modulated while the radical species are not. The charged and neutral species concentrations at atmospheric pressure with air impurity levels up to 10 000 ppm are predicted. The negative ion densities are very small but increase as the air impurity level is raised, which indicates that in helium-based systems operated in open air the concentration of negative ions would be significant. If water vapor at typical humidity levels is present as one of the impurities, hydrated cluster ions eventually comprise a significant fraction of the charged species.

  5. Use of nose cap and fuselage pressure orifices for determination of air data for space shuttle orbiter below supersonic speeds

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Siemers, P. M., III

    1980-01-01

    Wind tunnel pressure measurements were acquired from orifices on a 0.1 scale forebody model of the space shuttle orbiter that were arranged in a preliminary configuration of the shuttle entry air data system (SEADS). Pressures from those and auxiliary orifices were evaluated for their ability to provide air data at subsonic and transonic speeds. The orifices were on the vehicle's nose cap and on the sides of the forebody forward of the cabin. The investigation covered a Mach number range of 0.25 to 1.40 and an angle of attack range from 4 deg. to 18 deg. An air data system consisting of nose cap and forebody fuselage orifices constitutes a complete and accurate air data system at subsonic and transonic speeds. For Mach numbers less than 0.80 orifices confined to the nose cap can be used as a complete and accurate air data system. Air data systems that use only flush pressure orifices can be used to determine basic air data on other aircraft at subsonic and transonic speeds.

  6. High-Reynolds-number turbulent-boundary-layer wall pressure fluctuations with skin-friction reduction by air injection.

    PubMed

    Winkel, Eric S; Elbing, Brian R; Ceccio, Steven L; Perlin, Marc; Dowling, David R

    2008-05-01

    The hydrodynamic pressure fluctuations that occur on the solid surface beneath a turbulent boundary layer are a common source of flow noise. This paper reports multipoint surface pressure fluctuation measurements in water beneath a high-Reynolds-number turbulent boundary layer with wall injection of air to reduce skin-friction drag. The experiments were conducted in the U.S. Navy's Large Cavitation Channel on a 12.9-m-long, 3.05-m-wide hydrodynamically smooth flat plate at freestream speeds up to 20 ms and downstream-distance-based Reynolds numbers exceeding 200 x 10(6). Air was injected from one of two spanwise slots through flush-mounted porous stainless steel frits (approximately 40 microm mean pore diameter) at volume flow rates from 17.8 to 142.5 l/s per meter span. The two injectors were located 1.32 and 9.78 m from the model's leading edge and spanned the center 87% of the test model. Surface pressure measurements were made with 16 flush-mounted transducers in an "L-shaped" array located 10.7 m from the plate's leading edge. When compared to no-injection conditions, the observed wall-pressure variance was reduced by as much as 87% with air injection. In addition, air injection altered the inferred convection speed of pressure fluctuation sources and the streamwise coherence of pressure fluctuations.

  7. Association between long-term air pollution and increased blood pressure and hypertension in China.

    PubMed

    Dong, Guang-Hui; Qian, Zhengmin Min; Xaverius, Pamela K; Trevathan, Edwin; Maalouf, Salwa; Parker, Jamaal; Yang, Laiji; Liu, Miao-Miao; Wang, Da; Ren, Wan-Hui; Ma, Wenjun; Wang, Jing; Zelicoff, Alan; Fu, Qiang; Simckes, Maayan

    2013-03-01

    Several studies have investigated the short-term effects of ambient air pollutants in the development of high blood pressure and hypertension. However, little information exists regarding the health effects of long-term exposure. To investigate the association between residential long-term exposure to air pollution and blood pressure and hypertension, we studied 24 845 Chinese adults in 11 districts of 3 northeastern cities from 2009 to 2010. Three-year average concentration of particles with an aerodynamic diameter ≤10 µm (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxides (NO(2)), and ozone (O(3)) were calculated from monitoring stations in the 11 districts. We used generalized additive models and 2-level logistic regressions models to examine the health effects. The results showed that the odds ratio for hypertension increased by 1.12 (95% confidence interval [CI], 1.08-1.16) per 19 μg/m(3) increase in PM(10), 1.11 (95% CI, 1.04-1.18) per 20 μg/m(3) increase in SO(2), and 1.13 (95% CI, 1.06-1.20) per 22 μg/m(3) increase in O(3). The estimated increases in mean systolic and diastolic blood pressure were 0.87 mm Hg (95% CI, 0.48-1.27) and 0.32 mm Hg (95% CI, 0.08-0.56) per 19 μg/m(3) interquartile increase in PM(10), 0.80 mm Hg (95% CI, 0.46-1.14) and 0.31 mm Hg (95% CI, 0.10-0.51) per 20 μg/m(3) interquartile increase in SO(2), and 0.73 mm Hg (95% CI, 0.35-1.11) and 0.37 mm Hg (95% CI, 0.14-0.61) per 22 μg/m(3) interquartile increase in O(3). These associations were only statistically significant in men. In conclusion, long-term exposure to PM(10), SO(2), and O(3) was associated with increased arterial blood pressure and hypertension in the study population.

  8. Energy of electrons generated during a subnanosecond breakdown in atmospheric-pressure air

    SciTech Connect

    Tarasenko, V. F. Baksht, E. Kh.; Burachenko, A. G.; Kostyrya, I. D.; Rybka, D. V.

    2013-07-15

    The influence of the cathode design on the energy of the main group of electrons generated during a subnanosecond breakdown in atmospheric-pressure air was studied experimentally. The electron energy was measured using a time-of-flight spectrometer with a picosecond time resolution. It is shown that the energy of the main group of electrons increases with increasing cathode curvature radius. It is established using 400- to 650-{mu}m-thick aluminum foils that the electron energy reaches its maximum value in voltage pulses with abrupt trailing edges and amplitudes below the maximum amplitude. Electrons with maximum energies are generated with a stronger spatial and amplitude scatter than those with average energies.

  9. A simple atmospheric pressure room-temperature air plasma needle device for biomedical applications

    NASA Astrophysics Data System (ADS)

    Lu, X.; Xiong, Z.; Zhao, F.; Xian, Y.; Xiong, Q.; Gong, W.; Zou, C.; Jiang, Z.; Pan, Y.

    2009-11-01

    Rather than using noble gas, room air is used as the working gas for an atmospheric pressure room-temperature plasma. The plasma is driven by submicrosecond pulsed directed current voltages. Several current spikes appear periodically for each voltage pulse. The first current spike has a peak value of more than 1.5 A with a pulse width of about 10 ns. Emission spectra show that besides excited OH, O, N2(C-B), and N2+(B-X) emission, excited NO, N2(B-A), H, and even N emission are also observed in the plasma, which indicates that the plasma may be more reactive than that generated by other plasma jet devices. Utilizing the room-temperature plasma, preliminary inactivation experiments show that Enterococcus faecalis can be killed with a treatment time of only several seconds.

  10. Simulations of nanosecond-pulsed dielectric barrier discharges in atmospheric pressure air

    SciTech Connect

    Soo Bak, Moon; Cappelli, Mark A.

    2013-03-21

    This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge accumulation and secondary emission from the grounded electrode eventually lead to sheath collapse. One interesting feature is a predicted reversal in gap potential due to the accumulated charge, even when there is no reversal in applied potential. The simulation results are compared to recent measurement of mid-gap electric field under the same discharge conditions [Ito et al., Phys. Rev. Lett. 107, 065002 (2011)].

  11. Characteristics of Low Power CH4/Air Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    ZHANG, Jun; XIAO, Dezhi; FANG, Shidong; SHU, Xingsheng; ZUO, Xiao; CHENG, Cheng; MENG, Yuedong; WANG, Shouguo

    2015-03-01

    A low power atmospheric pressure plasma jet driven by a 24 kHz AC power source and operated with a CH4/air gas mixture has been investigated by optical emission spectrometer. The plasma parameters including the electron excitation temperature, vibrational temperature and rotational temperature of the plasma jet at different discharge powers are diagnosed based on the assumption that the kinetic energy of the species obeys the Boltzmann distribution. The electron density at different power is also investigated by Hβ Stark broadening. The results show that the plasma source works under non-equilibrium conditions. It is also found that the vibrational temperature and rotational temperature increase with discharge power, whereas the electron excitation temperature seems to have a downward trend. The electron density increases from 0.8 × 1021 m-3 to 1.1 × 1021 m-3 when the discharge power increases from 53 W to 94 W.

  12. Atmospheric pressure discharge plasma decomposition for gaseous air contaminants -- Trichlorotrifluoroethane and trichloroethylene

    SciTech Connect

    Oda, Tetsuji; Yamashita, Ryuichi; Takahashi, Tadashi; Masuda, Senichi

    1996-03-01

    The decomposition performance of gaseous environmental destructive contaminants in air by using atmospheric pressure discharged plasma including the surface discharge induced plasma chemical processing (SPCP) was examined. The main contaminants tested were chlorofluorocarbon (CFC-113) and trichloroethylene, typically. The discharge exciting frequency range studied was wide--50 Hz to 50 kHz. Results showed the low frequency discharge requires high voltage to inject high electric power in the gas and to decompose the contaminants. A Gas Chromatograph Mass Spectrometer was used to analyze discharge products of dense CFC-113 or trichloroethylene. Among the detected products were HCl, CClFO, and CHCl{sub 3}. Two different electrode configurations; the silent discharge (coaxial) electrode and the coil-electrode were also tested and compared to each other as a gas reactor.

  13. Synthesis of ammonia directly from air and water at ambient temperature and pressure.

    PubMed

    Lan, Rong; Irvine, John T S; Tao, Shanwen

    2013-01-01

    The N≡N bond (225 kcal mol⁻¹) in dinitrogen is one of the strongest bonds in chemistry therefore artificial synthesis of ammonia under mild conditions is a significant challenge. Based on current knowledge, only bacteria and some plants can synthesise ammonia from air and water at ambient temperature and pressure. Here, for the first time, we report artificial ammonia synthesis bypassing N₂ separation and H₂ production stages. A maximum ammonia production rate of 1.14 × 10⁻⁵ mol m⁻² s⁻¹ has been achieved when a voltage of 1.6 V was applied. Potentially this can provide an alternative route for the mass production of the basic chemical ammonia under mild conditions. Considering climate change and the depletion of fossil fuels used for synthesis of ammonia by conventional methods, this is a renewable and sustainable chemical synthesis process for future.

  14. Interaction of high-power microwave with air breakdown plasma at low pressure

    NASA Astrophysics Data System (ADS)

    Zhao, Pengcheng; Guo, Lixin; Shu, Panpan

    2016-09-01

    The high-power microwave breakdown at the low air pressure (about 0.01 atm) is simulated numerically using the one-dimensional model coupling Maxwell's equations with plasma fluid equations. The accuracy of the model is validated by comparing the breakdown prediction with the experimental data. We find that a diffuse plasma with a stationary front profile forms due to the large electron diffusion. Most of the incident wave energy is absorbed and reflected by the plasma when the plasma front achieves a stationary profile. The front propagation velocity remains almost unchanged with time and increases when the incident wave amplitude increases or the incident wave frequency decreases. With the incident wave frequency increasing, the maximum density of the stationary plasma front increases, while the ratio of the reflected wave power to the incident wave power remains almost unchanged. At a higher incident wave amplitude, the maximum density and reflectance become large.

  15. Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Zhao, Huanhuan; Jia, Pengying

    2013-11-01

    Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.

  16. Response of atmospheric pressure and air temperature to the solar events in October 2003

    NASA Astrophysics Data System (ADS)

    Avakyan, S. V.; Voronin, N. A.; Nikol'sky, G. A.

    2015-12-01

    Variations in the main weather parameters were studied for effects of solar flares and magnetic storms: the air temperature T and the atmospheric pressure P. We report the results of our comparison of these parameters measured at the mountain meteorological observatory near Kislovodsk (2100 m above sea level) to the monitoring data on strong solargeomagnetic perturbations for October 2003. We observed a decrease in the value of P for medium and large flares (of the type M > 4) in nine cases (82%) and an increase in T after magnetic storms with K p > 5 in 16 cases (84%). Hence, the manifestation of solar flares and magnetic storms in weather parameter variations ( T and P) at an altitude of 2100 m was proven, and the contribution of the radiooptical three-step trigger mechanism to solar-weather relations was qualitatively confirmed.

  17. Responses of differentiated primary human lung epithelial cells to exposure to diesel exhaust at an air-liquid interface.

    PubMed

    Seagrave, JeanClare; Dunaway, Sandy; McDonald, Jacob D; Mauderly, Joe L; Hayden, Patrick; Stidley, Christine

    2007-01-01

    In vitro responses of potential target cell types to air pollutants under physiological conditions may be useful in understanding the health effects of air pollution exposure. The study evaluated responses of human primary airway epithelial cells to diesel exhaust (DE). Cultures of cells from 3 donors, differentiated by culture on membranes with the apical surfaces exposed to the atmosphere, were exposed to filtered air or DE. Some exposure-related effects were similar among donors, whereas others were affected by the donor, consistent with human population heterogeneity. This model may be useful for mechanistic and comparative toxicology studies. PMID:17364910

  18. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Rivera, Andrew; Birdsell, Dawn N.; Wagner, David M.; Zenhausern, Frederic

    2015-12-01

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30-100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

  19. Soot Surface Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix I

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2003-01-01

    Soot surface oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round fuel jets burning in coflowing dry air considering acetylene-nitrogen, ethylene, propyiene-nitrogen, propane and acetylene-benzene-nitrogen in the fuel stream. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of major stable gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2, C2H6, C3H6, C3H8, and C6H6) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by deconvoluted Li/LiOH atomic absorption and flow velocities by laser velocimetry. For present test conditions, it was found that soot surface oxidation rates were not affected by fuel type, that direct rates of soot surface oxidation by O2 estimated from Nagle and Strickland-Constable (1962) were small compared to observed soot surface oxidation rates because soot surface oxidation was completed near the flame sheet where O2 concentrations were less than 3% by volume, and that soot surface oxidation rates were described by the OH soot surface oxidation mechanism with a collision efficiency of 0.14 and an uncertainty (95% confidence) of +/- 0.04 when allowing for direct soot surface oxidation by O2, which is in reasonably good agreement with earlier observations of soot surface oxidation rates in both premixed and diffusion flames at atmospheric pressure.

  20. Helium:oxygen versus air:oxygen noninvasive positive-pressure ventilation in patients exposed to sulfur mustard.

    PubMed

    Ghanei, Mostafa; Rajaeinejad, Mohsen; Motiei-Langroudi, Rouzbeh; Alaeddini, Farshid; Aslani, Jafar

    2011-01-01

    Exposure to sulfur mustard (SM) causes a variety of respiratory symptoms, such as chronic bronchitis and constrictive bronchiolitis. This study assessed the effectiveness of noninvasive positive-pressure ventilation, adjunct with 79:21 helium:oxygen instead of 79:21 air:oxygen, in 24 patients with a previous exposure to SM presenting with acute respiratory failure. Both air:oxygen and helium:oxygen significantly decreased systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse rate, respiratory rate, dyspnea, and increased oxygen saturation (P values: .007, .029, .002, <.001, <.001, <.001, and .002 for air:oxygen, respectively, and <.001, .020, .001, <.001, <.001, <.001, and .002, for helium:oxygen, respectively). Moreover, helium:oxygen more potently improved systolic pressure, mean arterial pressure, pulse rate, respiratory rate, and dyspnea (P values: .012, .048, <.001, <.001, and .012, respectively). The results of our study support the benefit of using helium:oxygen adjunct with noninvasive positive-pressure ventilation in patients exposed to SM with acute respiratory decompensation.

  1. Localized etching of polymer films using an atmospheric pressure air microplasma jet

    NASA Astrophysics Data System (ADS)

    Guo, Honglei; Liu, Jingquan; Yang, Bin; Chen, Xiang; Yang, Chunsheng

    2015-01-01

    A direct-write process device based on the atmospheric pressure air microplasma jet (AμPJ) has been developed for the localized etching of polymer films. The plasma was generated by the air discharge ejected out through a tip-nozzle (inner diameter of 100 μm), forming the microplasma jet. The AμPJ was capable of reacting with the polymer surface since it contains a high concentration of oxygen reactive species and thus resulted in the selective removal of polymer films. The experimental results demonstrated that the AμPJ could fabricate different microstructures on a parylene-C film without using any masks or causing any heat damage. The etch rate of parylene-C reached 5.1 μm min-1 and microstructures of different depth and width could also be realized by controlling two process parameters, namely, the etching time and the distance between the nozzle and the substrate. In addition, combining XPS analysis and oxygen-induced chemical etching principles, the potential etching mechanism of parylene-C by the AμPJ was investigated. Aside from the etching of parylene-C, micro-holes on the photoresist and polyimide film were successfully created by the AμPJ. In summary, maskless pattern etching of polymer films could be achieved using this AμPJ.

  2. Use of MODIS Cloud Top Pressure to Improve Assimilation Yields of AIRS Radiances in GSI

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi

    2014-01-01

    Improvements to global and regional numerical weather prediction have been demonstrated through assimilation of data from NASA's Atmospheric Infrared Sounder (AIRS). Current operational data assimilation systems use AIRS radiances, but impact on regional forecasts has been much smaller than for global forecasts. Previously, it has been shown that cloud top designation associated with quality control procedures within the Gridpoint Statistical Interpolation (GSI) system used operationally by a number of Joint Center for Satellite Data Assimilation (JCSDA) partners may not provide the best representation of cloud top pressure (CTP). Because this designated CTP determines which channels are cloud-free and, thus, available for assimilation, ensuring the most accurate representation of this value is imperative to obtaining the greatest impact from satellite radiances. This paper examines the assimilation of hyperspectral sounder data used in operational numerical weather prediction by comparing analysis increments and numerical forecasts generated using operational techniques with a research technique that swaps CTP from the Moderate-resolution Imaging Spectroradiometer (MODIS) for the value of CTP calculated from the radiances within GSI.

  3. Afterglow chemistry of atmospheric-pressure helium-oxygen plasmas with humid air impurity

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

    2014-04-01

    The formation of reactive species in the afterglow of a radio-frequency-driven atmospheric-pressure plasma in a fixed helium-oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means of an extensive global plasma chemical kinetics model. As an original objective, we explore the effects of humid air impurity on the biologically relevant reactive species in an oxygen-dependent system. After a few milliseconds in the afterglow environment, the densities of atomic oxygen (O) decreases from 1015 to 1013 cm-3 and singlet delta molecular oxygen (O2(1D)) of the order of 1015 cm-3 decreases by a factor of two, while the ozone (O3) density increases from 1014 to 1015 cm-3. Electrons and oxygen ionic species, initially of the order of 1011 cm-3, recombine much faster on the time scale of some microseconds. The formation of atomic hydrogen (H), hydroxyl radical (OH), hydroperoxyl (HO2), hydrogen peroxide (H2O2), nitric oxide (NO) and nitric acid (HNO3) resulting from the humid air impurity as well as the influence on the afterglow chemistry is clarified with particular emphasis on the formation of dominant reactive oxygen species (ROS). The model suggests that the reactive species predominantly formed in the afterglow are major ROS O2(1D) and O3 (of the order of 1015 cm-3) and rather minor hydrogen- and nitrogen-based reactive species OH, H2O2, HNO3 and NO2/NO3, of which densities are comparable to the O-atom density (of the order of 1013 cm-3). Furthermore, the model quantitatively reproduces the experimental results of independent O and O3 density measurements.

  4. Biphasic Aire expression in early embryos and in medullary thymic epithelial cells before end-stage terminal differentiation.

    PubMed

    Nishikawa, Yumiko; Hirota, Fumiko; Yano, Masashi; Kitajima, Hiroyuki; Miyazaki, Jun-ichi; Kawamoto, Hiroshi; Mouri, Yasuhiro; Matsumoto, Mitsuru

    2010-05-10

    The roles of autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) in the organization of the thymic microenvironment for establishing self-tolerance are enigmatic. We sought to monitor the production and maintenance of Aire-expressing mTECs by a fate-mapping strategy in which bacterial artificial chromosome transgenic (Tg) mice expressing Cre recombinase under the control of the Aire regulatory element were crossed with a GFP reporter strain. We found that, in addition to its well recognized expression within mature mTECs, Aire was expressed in the early embryo before emergence of the three germ cell layers. This observation may help to explain the development of ectodermal dystrophy often seen in patients with AIRE deficiency. With the use of one Tg line in which Cre recombinase expression was confined to mTECs, we found that Aire(+)CD80(high) mTECs further progressed to an Aire(-)CD80(intermediate) stage, suggesting that Aire expression is not constitutive from after its induction until cell death but instead is down-regulated at the beginning of terminal differentiation. We also demonstrated that many mTECs of Aire-expressing lineage are in close contact with thymic dendritic cells. This close proximity may contribute to transfer of tissue-restricted self-antigens expressed by mTECs to professional antigen-presenting cells.

  5. Unique erosion features of hafnium cathode in atmospheric pressure arcs of air, nitrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Ghorui, S.; Meher, K. C.; Kar, R.; Tiwari, N.; Sahasrabudhe, S. N.

    2016-07-01

    Experimental investigation of cathode erosion in atmospheric pressure hafnium-electrode plasma torches is reported under different plasma environments along with the results of numerical simulation. Air, nitrogen and oxygen are the plasma gases considered. Distinct differences in the erosion features in different plasmas are brought out. Cathode images exhibiting a degree of erosion and measured erosion rates are presented in detail as a function of time of arc operation and arc current. Physical erosion rates are determined using high precision balance. The changes in the surface microstructures are investigated through scanning electron microscopy (SEM). Evolution of cathode chemistry is determined using energy dispersive x-ray spectroscopy (EDX). Numerical simulation with proper consideration of the plasma effects is performed for all the plasma gases. The important role of electromagnetic body forces in shaping the flow field and the distribution of pressure in the region is explored. It is shown that the mutual interaction between fluid dynamic and electromagnetic body forces may self-consistently evolve a situation of an extremely low cathode erosion rate.

  6. Effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1976-01-01

    In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. Flow is shown to provide a modest increase in TL that is uniform with frequency up to the critical frequency. The increase is about 2 dB at Mach number M = 0.5, and about 3.5 dB at M = 1. Above the critical frequency where TL is damping controlled, the increase can be slightly larger at certain frequencies. Curvature is found to stiffen the panel, thereby increasing the TL at low frequencies, but also to introduce a dip at the 'ring frequency' of a full cylinder having the same radius as the panel. Pressurization appears to produce a slight decrease in TL throughout the frequency range, and also slightly shifts the dips at the critical frequency and at the ring frequency.

  7. Phenol production in benzene/air plasmas at atmospheric pressure. Role of radical and ionic routes.

    PubMed

    Ascenzi, Daniela; Franceschi, Pietro; Guella, Graziano; Tosi, Paolo

    2006-06-29

    Benzene can be efficiently converted into phenol when it is treated by either corona or dielectric barrier discharge (DBD) plasmas operating at atmospheric pressure in air or mixtures of N(2) and O(2). Phenol produced by corona discharge in an atmospheric pressure chemical ionization source (APCI) has been detected as the corresponding radical cation C(6)H(5)OH(+*) at m/z 94 by an ion trap mass spectrometer. On the other hand, phenol has been observed also as neutral product by gas chromatography-mass spectrometry analysis (GC-MS) after treatment in a DBD plasma. Experiments aimed at shading light on the elementary processes responsible for benzene oxidation were carried out (i) by changing the composition of the gas in the corona discharge source; (ii) by using isotopically labeled reagents; and (iii) by investigating some relevant ion-molecule reactions (i.e. C(6)H(6)(+*) + O(2), C(6)H(5)(+) + O(2)) via selected guided ion beam measurements and with the help of ab initio calculations. The results of our approach show that ionic mechanisms do not play a significant role in phenol production, which can be better explained by radical reactions resulting in oxygen addition to the benzene ring followed by 1,2 H transfer.

  8. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    PubMed

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. PMID:27183129

  9. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution

    PubMed Central

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. PMID:27183129

  10. Air jet erosion test on plasma sprayed surface by varying erodent impingement pressure and impingement angle

    NASA Astrophysics Data System (ADS)

    Behera, Ajit; Behera, Asit; Mishra, S. C.; Pani, S.; Parida, P.

    2015-02-01

    Fly-ash premixed with quartz and illmenite powder in different weight proportions are thermal sprayed on mild steel and copper substrates at various input power levels of the plasma torch ranging from 11 kW to 21 kW DC. The erosion test has done using Air Jet erosion test Reg (As per ASTM G76) with silica erodent typically 150-250 pm in size. Multiple tests were performed at increasing the time duration from 60 sec to 180 sec with increasing pressure (from 1 bar to 2.5 bar) and angle (60° & 90°). This study reveals that the impact velocity and impact angle are two most significant parameters among various factors influencing the wear rate of these coatings. The mechanisms and microstructural changes that arise during erosion wear are studied by using SEM. It is found that, when erodent are impacting the fresh un-eroded surface, material removal occurs by the continuous evolution of craters on the surface. Upper layer splats are removed out after 60 sec and second layer splat erosion starts. Based on these observations Physical models are developed. Some graphs plotted between mass loss-rate versus time period/impact Pressure/impact Angle gives good correlation with surface features observed.

  11. Measurements of Electron Temperature and Gas Temperature in a Pulsed Atmospheric Pressure Air Discharge

    NASA Astrophysics Data System (ADS)

    Leipold, Frank; Hufney Mohamed, Abdel-Aleam; Schoenbach, Karl H.

    2001-10-01

    The application of electrical pulses with duration shorter than the time constant for glow-to-arc transition allows us to shift the electron energy distribution in high pressure glow discharges temporally to high energy values [1]. Application of these nonequilibrium plasmas are plasma ramparts, plasma reactors, and excimer light sources. In order to obtain information on the electron energy distribution , or electron energy, respectively, and the gas temperature with the required temporal resolution of 1 ns, we have explored two diagnostic methods. One is based on the evaluation of the bremsstrahlung. This method allows us to determine the electron temperature [2]. The gas temperature is obtained from the rotational spectrum of the second positive system of nitrogen. The results of measurement on a 10 ns pulsed atmospheric pressure air glow will be presented. References [1] Robert H. Stark and Karl H. Schoenbach, J. Appl. Phys. 89, 3568 (2001) [2] Jaeyoung Park, Ivars Henins, Hans W. Herrmann, and Gary S. Selwyn, Physics of Plasmas 7, 3141 (2000). [3] R. Block, O. Toedter, and K. H. Schoenbach, Bull. APS 43, 1478 (1998)

  12. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    PubMed

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma.

  13. Effects of moderate strength cold air exposure on blood pressure and biochemical indicators among cardiovascular and cerebrovascular patients.

    PubMed

    Zhang, Xiakun; Zhang, Shuyu; Wang, Chunling; Wang, Baojian; Guo, Pinwen

    2014-02-27

    The effects of cold air on cardiovascular and cerebrovascular diseases were investigated in an experimental study examining blood pressure and biochemical indicators. Zhangye, a city in Gansu Province, China, was selected as the experimental site. Health screening and blood tests were conducted, and finally, 30 cardiovascular disease patients and 40 healthy subjects were recruited. The experiment was performed during a cold event during 27-28 April 2013. Blood pressure, catecholamine, angiotensin II (ANG-II), cardiac troponin I (cTnI), muscle myoglobin (Mb) and endothefin-1 (ET-1) levels of the subjects were evaluated 1 day before, during the 2nd day of the cold exposure and 1 day after the cold air exposure. Our results suggest that cold air exposure increases blood pressure in cardiovascular disease patients and healthy subjects via the sympathetic nervous system (SNS) that is activated first and which augments ANG-II levels accelerating the release of the norepinephrine and stimulates the renin-angiotensin system (RAS). The combined effect of these factors leads to a rise in blood pressure. In addition, cold air exposure can cause significant metabolism and secretion of Mb, cTnI and ET-1 in subjects; taking the patient group as an example, ET-1 was 202.7 ng/L during the cold air exposure, increased 58 ng/L compared with before the cold air exposure, Mb and cTnI levels remained relatively high (2,219.5 ng/L and 613.2 ng/L, increased 642.1 ng/L and 306.5 ng/L compared with before the cold air exposure, respectively) 1-day after the cold exposure. This showed that cold air can cause damage to patients' heart cells, and the damage cannot be rapidly repaired. Some of the responses related to the biochemical markers indicated that cold exposure increased cardiovascular strain and possible myocardial injury.

  14. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  15. Pulsed positive discharges in air at moderate pressures near a dielectric rod

    NASA Astrophysics Data System (ADS)

    Dubinova, A.; Trienekens, D.; Ebert, U.; Nijdam, S.; Christen, T.

    2016-10-01

    We study pulsed positive discharges in air in a cylindrically symmetric setup with an electrode needle close (about 1 mm) above the top of a dielectric cylindrical rod of 4 mm in diameter mounted at its bottom on a grounded plate electrode. We present ICCD (intensified charge-coupled device) pictures and evaluations of experiments as well as simulations with a fluid discharge model; the simulations use cylindrical symmetry. In the experiments, there is an initial inception cloud phase, where the cylindrical symmetry is maintained, and later a streamer phase, where it is broken spontaneously. At 75-150 mbar, discharges with cylindrical symmetry are not attracted to the dielectric rod, but move away from it. The dielectric rod plays the sole role of an obstacle that shades (in the context of photoionization) a cone-shaped part of the inception cloud; the cone size is determined by the geometry of the setup. The material properties of the dielectric rod, such as its dielectric permittivity and the efficiency of the photon induced secondary electron emission do not have a noticeable effect. This is due to the abundance of photoionization in air, which supplies a positive discharge with free electrons and allows it to propagate along the electric field lines. Using some simple field calculations, we show that field enhancement due to dielectric polarization does not play a significant role in our geometry as long as the discharge maintains its cylindrical symmetry. The field component towards the rod is insufficiently enhanced to cause the discharge to move towards the rod. Any additional electrons produced by the dielectric surface do not influence this discharge morphology. This interpretation is supported by both experiments and simulations. At higher pressures (400-600 mbar) or for larger gaps between the needle and the dielectric rod, the inception cloud reaches its maximal radius within the gap between needle and rod and destabilizes there. In those cases

  16. A transmission-line model of back-cavity dynamics for in-plane pressure-differential microphones.

    PubMed

    Kim, Donghwan; Kuntzman, Michael L; Hall, Neal A

    2014-11-01

    Pressure-differential microphones inspired by the hearing mechanism of a special parasitoid fly have been described previously. The designs employ a beam structure that rotates about two pivots over an enclosed back volume. The back volume is only partially enclosed due to open slits around the perimeter of the beam. The open slits enable incoming sound waves to affect the pressure profile in the microphone's back volume. The goal of this work is to study the net moment applied to pressure-differential microphones by an incoming sound wave, which in-turn requires modeling the acoustic pressure distribution within the back volume. A lumped-element distributed transmission-line model of the back volume is introduced for this purpose. It is discovered that the net applied moment follows a low-pass filter behavior such that, at frequencies below a corner frequency depending on geometrical parameters of the design, the applied moment is unaffected by the open slits. This is in contrast to the high-pass filter behavior introduced by barometric pressure vents in conventional omnidirectional microphones. The model accurately predicts observed curvature in the frequency response of a prototype pressure-differential microphone 2 mm × 1 mm × 0.5 mm in size and employing piezoelectric readout.

  17. A transmission-line model of back-cavity dynamics for in-plane pressure-differential microphones.

    PubMed

    Kim, Donghwan; Kuntzman, Michael L; Hall, Neal A

    2014-11-01

    Pressure-differential microphones inspired by the hearing mechanism of a special parasitoid fly have been described previously. The designs employ a beam structure that rotates about two pivots over an enclosed back volume. The back volume is only partially enclosed due to open slits around the perimeter of the beam. The open slits enable incoming sound waves to affect the pressure profile in the microphone's back volume. The goal of this work is to study the net moment applied to pressure-differential microphones by an incoming sound wave, which in-turn requires modeling the acoustic pressure distribution within the back volume. A lumped-element distributed transmission-line model of the back volume is introduced for this purpose. It is discovered that the net applied moment follows a low-pass filter behavior such that, at frequencies below a corner frequency depending on geometrical parameters of the design, the applied moment is unaffected by the open slits. This is in contrast to the high-pass filter behavior introduced by barometric pressure vents in conventional omnidirectional microphones. The model accurately predicts observed curvature in the frequency response of a prototype pressure-differential microphone 2 mm × 1 mm × 0.5 mm in size and employing piezoelectric readout. PMID:25373956

  18. An evaluation of Shuttle Entry Air Data System (SEADS) flight pressures - Comparisons with wind tunnel and theoretical predictions

    NASA Technical Reports Server (NTRS)

    Henry, M. W.; Wolf, H.; Siemers, Paul M., III

    1988-01-01

    The SEADS pressure data obtained from the Shuttle flight 61-C are analyzed in conjunction with the preflight database. Based on wind tunnel data, the sensitivity of the Shuttle Orbiter stagnation region pressure distribution to angle of attack and Mach number is demonstrated. Comparisons are made between flight and wind tunnel SEADS orifice pressure distributions at several points throughout the re-entry. It is concluded that modified Newtonian theory provides a good tool for the design of a flush air data system, furnishing data for determining orifice locations and transducer sizing. Ground-based wind tunnel facilities are capable of providing the correction factors necessary for the derivation of accurate air data parameters from pressure data.

  19. An Ultrasonic and Air Pressure Sensing System for Detection of Behavior before Getting out of Bed Aided by Fuzzy Theory

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hayato; Nakajima, Hiroshi; Taniguchi, Kazuhiko; Kobashi, Syoji; Hata, Yutaka

    This paper proposes a sensing system for a behavior detection system using an ultrasonic oscillosensor and an air pressure sensor. The ultrasonic oscillosensor sensor has a cylindrical tank filled with water. It detects the vibration of the target object from the signal reflected from the water surface. This sensor can detect a biological vibration by setting to the bottom bed frame. The air pressure sensor consists of a polypropylene sheet and an air pressure sensor, and detects the pressure information by setting under the bed's mattress. An increase (decrease) in the load placed on the bed is detected by the increase (decrease) in the pressure of the air held in the tube attached to the sheet. We propose a behavior detection system using both sensors, complementally. The system recognizes three states (nobody in bed, keeping quiet in bed, moving in bed) using both sensors, and we detect the behavior before getting out of bed by recognized these states. Fuzzy logic plays a primary role in the system. As the fundamental experiment, we applied the system to five healthy volunteers, the system successfully recognized three states, and detected the behavior before getting out of bed. As the clinical experiment, we applied the system to four elderly patients with dementia, the system exactly detected the behavior before getting out of the bed with enough time for medical care support.

  20. Dual-pump CARS of Air in a Heated Pressure Vessel up to 55 Bar and 1300 K

    NASA Technical Reports Server (NTRS)

    Cantu, Luca; Gallo, Emanuela; Cutler, Andrew D.; Danehy, Paul M.

    2014-01-01

    Dual-pump Coherent anti-Stokes Raman scattering (CARS) measurements have been performed in a heated pressure vessel at NASA Langley Research Center. Each measurement, consisting of 500 single shot spectra, was recorded at a fixed location in dry air at various pressures and temperatures, in a range of 0.03-55×10(exp 5) Pa and 300-1373 K, where the temperature was varied using an electric heater. The maximum output power of the electric heater limited the combinations of pressures and temperatures that could be obtained. Charts of CARS signal versus temperature (at constant pressure) and signal versus pressure (at constant temperature) are presented and fit with an empirical model to validate the range of capability of the dual-pump CARS technique; averaged spectra at different conditions of pressure and temperature are also shown.

  1. Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

    NASA Technical Reports Server (NTRS)

    Russin, W. R.

    1974-01-01

    Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

  2. Effects of nozzle exit geometry and pressure ratio on plume shape for nozzles exhausting into quiescent air

    NASA Technical Reports Server (NTRS)

    Scallion, William I.

    1991-01-01

    The effects of varying the exit geometry on the plume shapes of supersonic nozzles exhausting into quiescent air at several exit-to-ambient pressure ratios are given. Four nozzles having circular throat sections and circular, elliptical and oval exit cross sections were tested and the exit plume shapes are compared at the same exit-to-ambient pressure ratios. The resulting mass flows were calculated and are also presented.

  3. Pilot Study of the Effects of Simulated Turbine Passage Pressure on Juvenile Chinook Salmon Acclimated with Access to Air at Absolute Pressures Greater than Atmospheric

    SciTech Connect

    Carlson, Thomas J.; Abernethy, Cary S.

    2005-04-28

    The impacts of pressure on juvenile salmon who pass through the turbines of hydroelectric dams while migrating downstream on the Columbia and Snake rivers has not been well understood, especially as these impacts relate to injury to the fish's swim bladder. The laboratory studies described here were conducted by Pacific Northwest National Laboratory for the US Army Corps of Engineers Portland District at PNNL's fisheries research laboratories in 2004 to investigate the impacts of simulated turbine passage pressure on fish permitted to achieve neutral buoyancy at pressures corresponding to depths at which they are typically observed during downstream migration. Two sizes of juvenile Chinook salmon were tested, 80-100mm and 125-145mm total length. Test fish were acclimated for 22 to 24 hours in hyperbaric chambers at pressures simulating depths of 15, 30, or 60 ft, with access to a large air bubble. High rates of deflated swim bladders and mortality were observed. Our results while in conclusive show that juvenile salmon are capable of drawing additional air into their swimbladder to compensate for the excess mass of implanted telemetry devices. However they may pay a price in terms of increased susceptibility to injury, predation, and death for this additional air.

  4. Kinetic studies of NO formation in pulsed air-like low-pressure dc plasmas

    NASA Astrophysics Data System (ADS)

    Hübner, M.; Gortschakow, S.; Guaitella, O.; Marinov, D.; Rousseau, A.; Röpcke, J.; Loffhagen, D.

    2016-06-01

    The kinetics of the formation of NO in pulsed air-like dc plasmas at a pressure of 1.33 mbar and mean currents between 50 and 150 mA of discharge pulses with 5 ms duration has been investigated both experimentally and by self-consistent numerical modelling. Using time-resolved quantum cascade laser absorption spectroscopy, the densities of NO, NO2 and N2O have been measured in synthetic air as well as in air with 0.8% of NO2 and N2O, respectively. The temporal evolution of the NO density shows four distinct phases during the plasma pulse and the early afterglow in the three gas mixtures that were used. In particular, a steep density increase during the ignition phase and after termination of the discharge current pulse has been detected. The NO concentration has been found to reach a constant value of 0.57× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} , 1.05× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} , and 1.3× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} for mean plasma currents of 50 mA, 100 mA and 150 mA, respectively, in the afterglow. The measured densities of NO2 and N2O in the respective mixture decrease exponentially during the plasma pulse and remain almost constant in the afterglow, especially where the admixture of NO2 has a remarkable impact on the NO production during the ignition. The numerical results of the coupled solution of a set of rate equations for the various heavy particles and the time-dependent Boltzmann equation of the electrons agree quite well with the experimental findings for the different air-like plasmas. The main reaction processes have been analysed on the basis of the model calculations and the remaining differences between the experiment and modelling especially during the afterglow are discussed.

  5. 17. VIEW OF AIR LOCK ENTRY DOOR. BANKS OF AIR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. VIEW OF AIR LOCK ENTRY DOOR. BANKS OF AIR FILTERS ARE VISIBLE TO THE SIDES OF THE DOORS. THE BUILDING WAS DIVIDED INTO ZONES BY AIRLOCK DOORS AND AIR FILTERS. AIR PRESSURE DIFFERENTIALS WERE MAINTAINED IN THE ZONES, SUCH THAT AIRFLOW WAS PROGRESSIVELY TOWARD AREAS WITH THE HIGHEST POTENTIAL FOR CONTAMINATION. (9/24/91) - Rocky Flats Plant, Plutonium Manufacturing Facility, North-central section of Plant, just south of Building 776/777, Golden, Jefferson County, CO

  6. The association of annual air pollution exposure with blood pressure among patients with sleep-disordered breathing.

    PubMed

    Liu, Wen-Te; Lee, Kang-Yun; Lee, Hsin-Chien; Chuang, Hsiao-Chi; Wu, Dean; Juang, Jer-Nan; Chuang, Kai-Jen

    2016-02-01

    While sleep-disordered breathing (SDB), high blood pressure (BP) and air pollution exposure have separately been associated with increased risk of cardiopulmonary mortality, the association linking air pollution exposure to BP among patients with sleep-disordered breathing is still unclear. We collected 3762 participants' data from the Taipei Medical University Hospital's Sleep Center and air pollution data from the Taiwan Environmental Protection Administration. Associations of 1-year mean criteria air pollutants [particulate matter with aerodynamic diameters ≤10 μm (PM10), particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5), nitrogen dioxide (NO2) and ozone (O3)] with systolic BP (SBP) and diastolic BP (DBP) were investigated by generalized additive models. After controlling for age, sex, body mass index (BMI), temperature and relative humidity, we observed that increases in air pollution levels were associated with decreased SBP and increased DBP. We also found that patients with apnea-hypopnea index (AHI) ≥30 showed a stronger BP response to increased levels of air pollution exposure than those with AHI<30. Stronger effects of air pollution exposure on BP were found in overweight participants than in participants with normal BMI. We concluded that annual exposure to air pollution was associated with change of BP among patients with sleep-disordered breathing. The association between annual air pollution exposure and BP could be modified by AHI and BMI.

  7. Electronic structure computation and differential capacitance profile in δ-doped FET as a function of hydrostatic pressure

    SciTech Connect

    Carlos-Pinedo, C.; Rodríguez-Vargas, I.; Martínez-Orozco, J. C.

    2014-05-15

    In this work we present the results obtained from the calculation of the level structure of a n-type delta-doped well Field Effect Transistor when is subjected to hydrostatic pressure. We study the energy level structure as a function of hydrostatic pressure within the range of 0 to 6 kbar for different Schottky barrier height (SBH). We use an analytical expression for the effect of hydrostatic pressure on the SBH and the pressure dependence of the basic parameters of the system as the effective mass m(P) and the dielectric constant ε(P) of GaAs. We found that due to the effects of hydrostatic pressure, in addition to electronic level structure alteration, the profile of the differential capacitance per unit area C{sup −2} is affected.

  8. Investigations of cosmetic treatments on high-pressure differential scanning calorimetry.

    PubMed

    Marsh, J M; Clarke, C J; Meinert, K; Dahlgren, R M

    2007-01-01

    High Pressure Differential Scanning Calorimetry (HPDSC) can be used to gain information on both the degree of crystallinity in the intermediate filaments (IFs) and the structural rigidity of the surrounding matrix or intermediate filament associated proteins (IFAP) of the hair cortex. We have used HPDSC to measure changes in denaturation temperature (T(D)) and enthalpy (deltaH(D)) of the crystalline components after treatment with bleach products. Literature reports suggest that a decrease in peak denaturation temperature is indicative of permanent damage to the hair. However, changing the rigidity of the matrix surrounding the IFs, by temporarily changing electrostatic interactions, should also result in a similar decrease in peak temperature. The complex nature of bleach formulations including oxidants, alkalizers and salts suggests that several of the components could have a non-permanent affect on salt bridges and hydrogen bonds and hence rigidity or viscosity of the matrix. We have compared the denaturation temperature with levels of lightening (dL) and tensile properties of the fiber after treatment both before and after removal of actives from the fiber. It is evident that the HPDSC results are strongly influenced by formulation components and that these changes are reversible with extensive washing or dialysis. Combined with tensile data, it is proposed that a decrease in T(D) and deltaH(D) following treatment with bleach products can be due to both permanent and reversible changes to either the intermediate filaments or intermediate filament associated proteins of the hair fiber.

  9. Investigations of cosmetic treatments on high-pressure differential scanning calorimetry.

    PubMed

    Marsh, J M; Clarke, C J; Meinert, K; Dahlgren, R M

    2007-01-01

    High Pressure Differential Scanning Calorimetry (HPDSC) can be used to gain information on both the degree of crystallinity in the intermediate filaments (IFs) and the structural rigidity of the surrounding matrix or intermediate filament associated proteins (IFAP) of the hair cortex. We have used HPDSC to measure changes in denaturation temperature (T(D)) and enthalpy (deltaH(D)) of the crystalline components after treatment with bleach products. Literature reports suggest that a decrease in peak denaturation temperature is indicative of permanent damage to the hair. However, changing the rigidity of the matrix surrounding the IFs, by temporarily changing electrostatic interactions, should also result in a similar decrease in peak temperature. The complex nature of bleach formulations including oxidants, alkalizers and salts suggests that several of the components could have a non-permanent affect on salt bridges and hydrogen bonds and hence rigidity or viscosity of the matrix. We have compared the denaturation temperature with levels of lightening (dL) and tensile properties of the fiber after treatment both before and after removal of actives from the fiber. It is evident that the HPDSC results are strongly influenced by formulation components and that these changes are reversible with extensive washing or dialysis. Combined with tensile data, it is proposed that a decrease in T(D) and deltaH(D) following treatment with bleach products can be due to both permanent and reversible changes to either the intermediate filaments or intermediate filament associated proteins of the hair fiber. PMID:17728932

  10. Infradian, notably circaseptan testable feedsidewards among chronomes of the ECG and air temperature and pressure.

    PubMed

    Delyukov, A; Gorgo, Y; Cornélissen, G; Otsuka, K; Halberg, F

    2001-01-01

    To study the interactions among the natural physical environmental cycles and human infradian components of heart rate (HR) and HR variability (HRV), a healthy 49-year-old man in Kiev, who had monitored his electrocardiogram (ECG) around the clock earlier for 50 days, added at a later date with the same ambulatorily wearable device, a record of 70 days. The mean value of the R-R intervals (R-R), their standard deviation (SDNN) and other HRV endpoints, computed over consecutive 5-min intervals, served as markers of the subject's functional associations with the amplitude of fluctuations in atmospheric pressure (FAP) and the planetary Kp index of geomagnetic disturbance. About-weekly and half-weekly cycles in HRV endpoints indicate a reduction in physiological 'preparedness', here described as 'dynamics', of the subject investigated on Saturdays and Sundays and a sharp increase in 'dynamics' on Mondays. The waveform of the weekly oscillation seemed to be influenced by ambient air temperature and FAP. On Mondays, an FAP amplification or a temperature rise was accompanied by a significant decrease in R-R and SDNN, indicating an aggravation of a 'Monday effect' in physiological 'dynamics'. HRV endpoints also revealed about-5-day and about-12-day cyclic components similar to those found in FAP. The infradian pattern in a 70-day record differed from one found earlier in a 50-day record of the same subject. Changes in the natural physical environment (past as well as present), especially in air temperature and FAP, likely influence(d) if not synchronize(d) the amplitude and waveform of infradian weekly and half-weekly physiological cycles. Some of these infradians, their wobbly nature notwithstanding, may have been built into our temporal make-up by an evolutionary integration of life in the non-stationary quasi-periodic natural physical environment, which continues to contribute to variability. PMID:11774873

  11. Soot Oxidation in Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix K

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, propylene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2,C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable (1962), because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  12. Soot Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix D

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.

    2000-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, proplyene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, 02, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable, because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  13. Survey and bibliography on attainment of laminar flow control in air using pressure gradient and suction, volume 1

    NASA Technical Reports Server (NTRS)

    Bushnell, D. M.; Tuttle, M. H.

    1979-01-01

    A survey was conducted and a bibliography compiled on attainment of laminar flow in air through the use of favorable pressure gradient and suction. This report contains the survey, summaries of data for both ground and flight experiments, and abstracts of referenced reports. Much early information is also included which may be of some immediate use as background material for LFC applications.

  14. The Effect of Conceptual Change Approach to Eliminate 9th Grade High School Students' Misconceptions about Air Pressure

    ERIC Educational Resources Information Center

    Akbas, Yavuz; Gencturk, Ebru

    2011-01-01

    The aim of this study was to determine the effectiveness of teaching based on conceptual change overcome misconceptions of 9th grade high school students about the subject of air pressure. The sampling of the study was formed with two classes of 9th grade students from a general high school in the city-center of Trabzon. A quasi-experimental…

  15. Similarity laws for cathode-directed streamers in gaps with an inhomogeneous field at elevated air pressures

    SciTech Connect

    Bolotov, O. V.; Golota, V. I.; Kadolin, B. B.; Karas', V. I.; Ostroushko, V. N.; Zavada, L. M.; Shulika, A. Yu.

    2010-11-15

    Results are presented from experimental studies of cathode-directed streamers in the gap closure regime without a transition into spark breakdown. Spatiotemporal, electrodynamic, and spectroscopic characteristics of streamer discharges in air at different pressures were studied. Similarity laws for streamer discharges were formulated. These laws allow one to compare the discharge current characteristics and streamer propagation dynamics at different pressures. Substantial influence of gas photoionization on the deviations from the similarity laws was revealed. The existence of a pressure range in which the discharges develop in a similar way was demonstrated experimentally. In particular, for fixed values of the product pd and discharge voltage U, the average streamer velocity is also fixed. It is found that, although the similarity laws are violated in the interstreamer pause of the discharge, the average discharge current and the product of the pressure and the streamer repetition period remain the same at different pressures. The radiation spectra of the second positive system of nitrogen (the C{sup 3{Pi}}{sub u}-B{sup 3{Pi}}{sub g} transitions) in a wavelength range of 300-400 nm at air pressures of 1-3 atm were recorded. It is shown that, in the entire pressure range under study, the profiles of the observed radiation bands practically remain unchanged and the relative intensities of the spectral lines corresponding to the {sup 3{Pi}}{sub u}-B{sup 3{Pi}}{sub g} transitions are preserved.

  16. Suppression of Thyroarytenoid Muscle Responses During Repeated Air Pressure Stimulation of the Laryngeal Mucosa in Awake Humans

    PubMed Central

    Kearney, Pamela Reed; Poletto, Christopher J.; Mann, Eric A.; Ludlow, Christy L.

    2008-01-01

    Repeated stimulation of the laryngeal mucosa occurs during speech. Single stimuli, however, can elicit laryngeal adductor responses (LAR). Our hypothesis was that the LAR to repeated rapid air pressure stimuli are centrally suppressed in humans. Hooked wire electrodes were inserted into the thyroarytenoid and cricothyroid muscles bilaterally and into the posterior cricoarytenoid muscle on one side. Pairs of air puff stimuli were presented to the mucosa over the arytenoids at pressure levels three times threshold with inter-stimulus intervals from 250 to 5000 ms. Bilateral thyroarytenoid responses occurred at around 150 ms to over 70% of initial stimuli. With repeated presentation at intervals of 2 seconds or less, the percent occurrence decreased to less than 40% and response amplitudes were reduced by 50%. Central suppression of adductor responses to repeated air puff stimuli may allow speakers to produce voice without eliciting reflexive spasms which could disrupt speech. PMID:15895780

  17. [Differentiation of allotments for occupationally necessary and hygiene relevant costs of air technology designs for operating rooms].

    PubMed

    Seipp, H M; Sprengel, M; Wagner, K H

    1994-06-01

    The aeration of operation theatres serves multiple purposes. It is necessary for the regulation of room temperature (waste heat generated by the operation team and technical appliances), air exchange for oxygen supply, removal of narcotic gases and of smells (occupational limit values) as well the elimination of germs and particles emitted during operations by staff and from instruments (avoidance of germ transfer by air). This paper tries on the one hand to estimate the investment and running costs of different indoor air supplies according to the specifications given by DIN 1946, parts 2 and 4) and on the other hand to differentiate the hygienically relevant expenses of turbulent and laminar flow air supply systems. It can be seen that, due to the high heat production generated during operations, no cost can be saved through decreases in air flow volume. Depending on the operation frequency (e.g. 4 operations daily, 200-300 days per year) a hygienically relevant cost of DM 2.8-6.7 per patient is calculated for laminar flow supplies and DM 4.5-6.7 per patient for the turbulent air supply systems ("Stützstrahl"). Thus laminar flow systems are also cost-saving in comparison to turbulent air supply systems in addition to their significant technical and hygienic advantages. PMID:7916867

  18. Control of Air Leakage in Buildings.

    ERIC Educational Resources Information Center

    Wilson, A. Grant

    This discussion of air leakage emphasizes cause and provides suggestions for elimination of undesirable effects. Cause parameters described are--(1) pressure differential, (2) building shape, (3) temperature differential, (4) opening sizes, (5) mechanical system pressures, and (6) climatic factors. Effects discussed are--(1) increased mechanical…

  19. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Zhanguo; Li, Ying; Cao, Peng; Zhao, Hongjie

    2013-07-01

    An atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experimental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination process, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride (PVC), polyethylene (PE), phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chromatism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet.

  20. HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Steve Ruppel; Julia Gale; Jon Holder; Jon Olsen; Deanna Combs; Dhiraj Dembla; Leonel Gomez

    2003-12-10

    The Bureau of Economic Geology and Goldrus Producing Company have assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The characterization phase of the project is utilizing geoscientists and petroleum engineers from the Bureau of Economic Geology and the Department of Petroleum Engineering (both at The University of Texas at Austin) to define the controls on fluid flow in the reservoir as a basis for developing a reservoir model. This model will be used to define a field deployment plan that Goldrus, a small independent oil company, will implement by drilling both vertical and horizontal wells during the demonstration phase of the project. Additional reservoir data are being gathered during the demonstration phase to improve the accuracy of the reservoir model. The results of the demonstration will being closely monitored to provide a basis for improving the design of the HPAI field deployment plan. The results of the reservoir characterization field demonstration and monitoring program will be documented and widely disseminated to facilitate adoption of this technology by oil operators in the Permian Basin and elsewhere in the U.S.

  1. Nanosecond Repetitively Pulsed Discharges in Air at Atmospheric Pressure -- Experiment and Theory of Regime Transitions

    NASA Astrophysics Data System (ADS)

    Pai, David; Lacoste, Deanna; Laux, Christophe

    2009-10-01

    In atmospheric pressure air preheated from 300 to 1000 K, the Nanosecond Repetitively Pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and inter-electrode gap distance) of each discharge regime. Notably, there is a minimum gap distance for the existence of the glow regime that increases with decreasing gas temperature. A theory is developed to describe the Corona-to-Glow (C-G) and Glow-to-Spark (G-S) transitions for NRP discharges. The C-G transition is shown to depend on the Avalanche-to-Streamer Transition (AST) as well as the electric field strength in the positive column. The G-S transition is due to the thermal ionization instability. The minimum gap distance for the existence of the glow regime can be understood by considering that the applied voltage of the AST must be lower than that of the thermal ionization instability. This is a previously unknown criterion for generating glow discharges, as it does not correspond to the Paschen minimum or to the Meek-Raether criterion.

  2. Functionalization of graphene by atmospheric pressure plasma jet in air or H2O2 environments

    NASA Astrophysics Data System (ADS)

    Huang, Weixin; Ptasinska, Sylwia

    2016-03-01

    The functionalization of graphene, which deforms its band structure, can result in a metal-semiconductor transition. In this work, we report a facile strategy to oxidize single-layer graphene using an atmospheric pressure plasma jet (APPJ) that generates a variety of reactive plasma species at close to ambient temperature. We systematically characterized the oxygen content and chemical structure of the graphene films after plasma treatment under different oxidative conditions (ambient air atmosphere or hydrogen peroxide solution) by X-ray Photoelectron Spectroscopy (XPS). Plasma-treated graphene films containing more than 40% oxygen were obtained in both oxidative environments. Interestingly, prolonged irradiation led to the reduction of graphene oxides. N-doping of graphene also occurred during the APPJ treatment in H2O2 solution; the nitrogen content of the doped graphene was dependent on the duration of irradiation and reached up to 8.1% within 40 min. Moreover, the H2O2 solution served as a buffer layer that prevented damage to the graphene during plasma irradiation. Four-point probe measurement revealed an increase in sheet resistance of the plasma-treated graphene, indicating the transition of the material property from semi-metallic to semiconducting.

  3. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    NASA Astrophysics Data System (ADS)

    Begum, Asma; Laroussi, Mounir; Pervez, Mohammad Rasel

    2013-06-01

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 1011 cm-3 and it reaches to the maximum of 1012 cm-3.

  4. Characterization Of Nano-Second Laser Induced Plasmas From Al Target In Air At Atmospheric Pressure

    SciTech Connect

    Hegazy, H.; Abdel-Rahim, F. M.; Nossair, A. M. A.; Allam, S. H.; El-Sherbini, Th. M.

    2008-09-23

    In the present work we study the effect of the laser beam energy on the properties of the plasma generated by focusing an intense laser beam on Al solid target in air at atmospheric pressure. Plasma is generated using a Nd:YAG pulsed laser at 1064 nm wavelength, 6 ns pulse duration with a maximum pulse energy of 750mJ. The emission spectrum is collected using an Echelle spectrometer equipped with ICCD camera Andor type. The measurements were performed at several delay times between 0 to 9 {mu}s. Measurements of temperature and electron density of the produced plasmas at different laser energies and at different delay times are described using different emission spectral lines. Based on LTE assumption, excitation temperature is determined from the Boltzmann plot using O I spectral lines at 777.34, 794.93, and 848.65 nm and the electron density is determined from Stark width of Al II at 281.6 and 466.3 nm. The determined density is compared with the density determined from H{sub {alpha}} spectral line.

  5. Low temperature, atmospheric pressure, direct current microplasma jet operated in air, nitrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Mohamed, A.-A. H.; Kolb, J. F.; Schoenbach, K. H.

    2010-12-01

    Micro-plasma jets in atmospheric pressure molecular gases (nitrogen, oxygen, air) were generated by blowing these gases through direct current microhollow cathode discharges (MHCDs). The tapered discharge channel, drilled through two 100 to 200 μm thick molybdenum electrodes separated by a 200 μm thick alumina layer, is 150 to 450 μm in diameter in the cathode and has an opening of 100 to 300 μm in diameter in the anode. Sustaining voltages are 400 to 600 V, the maximum current is 25 mA. The gas temperature of the microplasma inside the microhollow cathode varies between ~2000 K and ~1000 K depending on current, gas, and flow rate. Outside the discharge channel the temperature in the jet can be reduced by manipulating the discharge current and the gas flow to achieve values close to room temperature. This cold microplasma jet can be used for surface treatment of heat sensitive substances, and for sterilization of contaminated areas.

  6. Xanthan production on polyurethane foam and its enhancement by air pressure pulsation.

    PubMed

    Zhang, Zhi-guo; Chen, Hong-zhang

    2010-12-01

    In this study, we evaluated the feasibility of solid-state fermentation (SSF) on polyurethane foam (PUF) for xanthan production. The effects of air pressure pulsation (APP) on biomass accumulation and final xanthan concentration were also studied. Under suitable conditions (15% inoculum, 0.5-cm (side length) PUF cubes, 15 mL medium per gram cubes and 4.5 cm bed depth), the broth was dispersed on the PUF as a film. When the initial glucose concentration in the media was low (20 and 40 g L⁻¹), there was no significant difference between the final xanthan concentration in static SSF and submerged fermentation (SMF). When high initial glucose concentrations (60 and 80 g L⁻¹) were used, the final gum concentrations in SSF were much higher than those in SMF. When the APP technique was applied in xanthan production with a medium containing a high glucose concentration (80 g L⁻¹), the oxygen consumption rate of Xanthomonas campestris was significantly enhanced at the later stages of fermentation, and both the biomass and xanthan concentration were improved. The results indicated that SSF on PUF is suitable for xanthan preparation, especially when the initial glucose concentration ranged from 60 to 80 g L⁻¹. Those results also demonstrated that APP technology can be used to enhance xanthan yields.

  7. Auto-ignition of lubricating oil working at high pressures in a compressor for an air conditioner.

    PubMed

    Kim, Chul Jin; Choi, Hyo Hyun; Sohn, Chae Hoon

    2011-01-15

    Auto-ignition of lubricating oil working in a compressor for an air conditioner is studied experimentally. The adopted lubricating oil is an unknown mixture with multi-components and known to have flash point temperature of 170 °C. First, its auto-ignition temperature is measured 365 °C at atmospheric pressure. The lubricating oil works under high-pressure condition up to 30 atm and it is heated and cooled down repeatedly. Accordingly, auto-ignition temperatures or flammable limits of lubricating oil are required at high pressures with respect to fire safety. Because there is not a standard test method for the purpose, a new ignition-test method is proposed in this study and thereby, auto-ignition temperatures are measured over the pressure range below 30 atm. The measured temperatures range from 215 °C to 255 °C and they strongly depend on pressure of gas mixture consisting of oil vapor, nitrogen, and oxygen. They are close to flash point temperature and the lubricating oil can be hazardous when it works for high-pressure operating condition and abundant air flows into a compressor. PMID:20934810

  8. Differential Velocity between Solar Wind Protons and Alpha Particles in Pressure Balance Structures

    NASA Technical Reports Server (NTRS)

    Yamauchi, Yohei; Suess, Steven T.; Steinberg, John T.; Sakurai, Takashi

    2004-01-01

    Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advected into and reconnects with the flux concentration. A minimum variance analysis (MVA) of magnetic discontinuities in PBSs showed there is a larger proportion of tangential discontinuities than in the surrounding high-speed wind, supporting the hypothesis that plasmoids or extended current sheets are formed during reconnection at the base of plumes. To further evaluate the character of magnetic field discontinuities in PBSs, differential streaming between alpha particles and protons is analyzed here for the same sample of PBSs used in the MVA. Alpha particles in high-speed wind generally have a higher radial flow speed than protons. However, if the magnetic field is folded back on itself, as in a large-amplitude Alfven wave, alpha particles will locally have a radial flow speed less than protons. This characteristic is used here to distinguish between folded back magnetic fields (which would contain rotational discontinuities) and tangential discontinuities using Ulysses high-latitude, high-speed solar wind data. The analysis indicates that almost all reversals in the radial magnetic field in PBSs are folded back field lines. This is found to also be true outside PBSs, supporting existing results for typical high-speed, high-latitude wind. There remains a small number of cases that appear not to be folds in the magnetic field and which may be flux tubes with both ends rooted in the Sun. The distinct difference in MVA results inside and outside PBSs remains unexplained.

  9. Recovery optimization by modeling depletion and fault block differential pressures at Green Canyon 110

    SciTech Connect

    Kikani, J.; Smith, T.D.

    1996-12-31

    A robust depletion/completion strategy for deepwater subsea wells is critical to the economic success of a project. Since recompletions are expensive and risky, commingling different horizons or fault blocks could be attractive. This option is now available due to recent regulatory policies which have moved away from specific reserve limits as a criteria for commingling. This paper describes the methodology and the results of a simulation study performed to evaluate the development options for Shell Offshore Inc.`s (SOI) first modern technology subsea oil well at Green Canyon (GC) 110 - a satellite development to Bullwinkle located in the same basin. The well SOI GC110-4 cutting across a fault at an angle of about 62{degrees}, indicated the existence of pressure differentials between the upthrown and downthrown blocks at current conditions. The two fault blocks communicate with each other through a common aquifer. At a datum depth of -11000 ft SS, the reservoir is depleted by about 750 psi compared to the well GC110-2 which was drilled in 1987 prior to the start of production from Bullwinkle. The seemingly fragmented data was reconciled into a reservoir model by accounting for basin depletion effects. A hypothesis about the reservoir and fault connectivities was used to address dynamic model initialization. A first order material balance estimate of basin depletion based on prospect Bullwinkle production data was used to tune the model. Based on this dynamic initialization, a completion strategy was developed. A number of development scenarios including sequential and commingled production as well as the effect of shutin on crossflow were considered. The results indicate that it will be prudent from the recovery and economic perspective to commingle the two fault blocks through GC110-4. This scenario provided the highest recovery at the lowest life cycle cost.

  10. Differentiation of (Mixed) Halogenated Dibenzo-p-Dioxins by Negative Ion Atmospheric Pressure Chemical Ionization.

    PubMed

    Fernando, Sujan; Green, M Kirk; Organtini, Kari; Dorman, Frank; Jones, Rhys; Reiner, Eric J; Jobst, Karl J

    2016-05-17

    Brominated and mixed halogenated dibenzo-p-dioxins (PBDDs and PXDDs) may well be as toxic as 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2378-TCDD), a compound reputed as one of the most toxic chemicals known to exist. However, studies on the occurrence of PXDDs have been hampered by a lack of authentic standards as well as separation techniques capable of resolving the enormous number of potential isomers. Electron ionization (EI) mass spectrometry based methods are of limited value due to the lack of isomer specific fragmentation. Negative ion atmospheric pressure chemical ionization (APCI(-)) of 2378-TCDD was described in this journal over 30 years ago. Under these conditions, the reaction between O2(-•) and 2378-TCDD results in structure diagnostic cleavages of the C-O bonds, which can distinguish TCDD isomers on the basis of Cl distribution between the two aromatic rings. In the present study, the analogous ether cleavages of PBDDs and PXDDs were studied using a gas chromatograph-quadrupole time-of-flight (GC-QTOF) mass spectrometer coupled using APCI. The results indicate comparable detection limits for the radical cations [M(•+)] and negative pseudomolecular ions [M-Cl+O](-): approximately 5 fg and 10 fg, respectively, for 2378-TCDD and 5-10 fg and 10-30 fg, respectively, for the 2,3,7,8-substituted PXDDs. Detection limits obtained by monitoring the ether cleavage products were somewhat higher (between 100 and 600 fg) but still acceptable for trace analysis of PXDDs. Such reactions may resolve coeluting isomers, which is crucial for the identification of PXDDs. The technique is demonstrated by differentiating PXDD isomer classes in a sample obtained from a major industrial fire that would not be feasible using EI or positive ion APCI(+). PMID:27074061

  11. Heat transfer and pressure drop measurements in an air/molten salt direct-contact heat exchanger

    SciTech Connect

    Bohn, M.S.

    1988-11-01

    This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610-mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440{degree}C and air inlet temperatures of approximately 230{degree}C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/m{sup 2} s air flow and 6 to 18 kg/m{sup 2} s salt flow, the data agree with the model within 22% standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18% standard deviation over the range of column pressure drop from 40 to 1250 Pa/m. 25 refs., 7 figs., 2 tabs.

  12. Indoor Air Pollution and Blood Pressure in Adult Women Living in Rural China

    PubMed Central

    Schauer, James J.; Ezzati, Majid; Lu, Lin; Cheng, Chun; Patz, Jonathan A.; Bautista, Leonelo E.

    2011-01-01

    Background: Almost half of the world’s population uses coal and biomass fuels for domestic energy. Limited evidence suggests that exposure to air pollutants from indoor biomass combustion may be associated with elevated blood pressure (BP). Objective: Our aim was to assess the relationship between air pollution exposure from indoor biomass combustion and BP in women in rural China. Methods: We measured 24-hr personal integrated gravimetric exposure to fine particles < 2.5 µm in aerodynamic diameter (PM2.5) and systolic BP (SBP) and diastolic BP (DBP) in the winter and summer among 280 women ≥ 25 years of age living in rural households using biomass fuels in Yunnan, China. We investigated the association between PM2.5 exposure and SBP and DBP using mixed-effects models with random intercepts to account for correlation among repeated measures. Results: Personal average 24-hr exposure to PM2.5 ranged from 22 to 634 µg/m3 in winter and from 9 to 492 µg/m3 in summer. A 1-log-µg/m3 increase in PM2.5 exposure was associated with 2.2 mm Hg higher SBP [95% confidence interval (CI), 0.8 to 3.7; p = 0.003] and 0.5 mm Hg higher DBP (95% CI, –0.4 to 1.3; p = 0.31) among all women; estimated effects varied by age group. Among women > 50 years of age, a 1-log-µg/m3 increase in PM2.5 exposure was associated with 4.1 mm Hg higher SBP (95% CI, 1.5 to 6.6; p = 0.002) and 1.8 mm Hg higher DBP (95% CI, 0.4 to 3.2; p = 0.01). PM2.5 exposure was positively associated with SBP among younger women, but the association was not statistically significant. Conclusion: PM2.5 exposure from biomass combustion may be a risk factor for elevated BP and hence for cardiovascular events. Our findings should be corroborated in longitudinal studies. PMID:21724522

  13. Studies on the tempo of bubble formation in recently cavitated vessels: a model to predict the pressure of air bubbles.

    PubMed

    Wang, Yujie; Pan, Ruihua; Tyree, Melvin T

    2015-06-01

    A cavitation event in a vessel replaces water with a mixture of water vapor and air. A quantitative theory is presented to argue that the tempo of filling of vessels with air has two phases: a fast process that extracts air from stem tissue adjacent to the cavitated vessels (less than 10 s) and a slow phase that extracts air from the atmosphere outside the stem (more than 10 h). A model was designed to estimate how water tension (T) near recently cavitated vessels causes bubbles in embolized vessels to expand or contract as T increases or decreases, respectively. The model also predicts that the hydraulic conductivity of a stem will increase as bubbles collapse. The pressure of air bubbles trapped in vessels of a stem can be predicted from the model based on fitting curves of hydraulic conductivity versus T. The model was validated using data from six stem segments each of Acer mono and the clonal hybrid Populus 84 K (Populus alba × Populus glandulosa). The model was fitted to results with root mean square error less than 3%. The model provided new insight into the study of embolism formation in stem tissue and helped quantify the bubble pressure immediately after the fast process referred to above.

  14. Optimal control of systems governed by differential equations with applications in air traffic management and systems biology

    NASA Astrophysics Data System (ADS)

    Raffard, Robin L.

    Differential equations are arguably the most widespread formalism to model dynamical systems in sciences and engineering. In this dissertation, we strive to design a practical methodology which can be used for the optimal control of most systems modeled by differential equations. Namely, the method is applicable to ordinary differential equations (ODEs), partial differential equations (PDEs) and stochastic differential equations (SDEs) driven by deterministic control. The algorithm draws from both optimization and control theory. It solves the Pontryagin Maximum Principle conditions in an iterative fashion via a novel approximate Newton method. We also extend the method to the case in which multiple agents are involved in the optimal control problem. For this purpose, we use dual decomposition techniques which allow us to decentralize the control algorithm and to distribute the computational load among each individual agent. Most of the dissertation is devoted to promoting the applicability of the method to practical problems in air traffic management and systems biology. In air traffic management; we use the technique to optimize a new PDE-based Eulerian model of the airspace; suitable to represent and control air traffic flow at the scale of the US national airspace. We also apply the technique to aircraft coordination problems in the context of formation flight, in which aircraft dynamics are described by ODEs. In systems biology, we use the method to perform fast parameter identification in the analysis of protein networks, which allows us to gain some insights about the biological processes regulating the system. In particular we perform parameter identification for a PDE model of a spatially distributed network of proteins, playing a key role in the planar cell polarity of Drosophila wings. We also study a general representation of intra-cellular genetic networks, described as a stochastic nonlinear regulatory network, in which our control system approach

  15. Microwave air plasmas in capillaries at low pressure II. Experimental investigation

    NASA Astrophysics Data System (ADS)

    Stancu, G. D.; Leroy, O.; Coche, P.; Gadonna, K.; Guerra, V.; Minea, T.; Alves, L. L.

    2016-11-01

    This work presents an experimental study of microwave (2.45 GHz excitation frequency) micro-plasmas, generated in dry air (N2 80%: O2 20%) within a small radius silica capillary (345 µm inner radius) at low pressure (300 Pa) and low powers (80–130 W). Experimental diagnostics are performed using optical emission spectroscopy calibrated in absolute intensity. Axial-resolved measurements (50 µm spatial resolution) of atomic transitions N(3p4S)  →  N(3s4P) O(3p5P)  →  O(3s5S) and molecular transitions N2(C,v‧)  →  N2(B,v″) \\text{N}2+ (B,v‧)  →  \\text{N}2+ (X,v″) allow us to obtain, as a function of the coupled power, the absolute densities of N(3p4S), O(3p5P), N2(C), N2(B) and \\text{N}2+ (B), as well as the gas (rotational) temperature (700–1000 K), the vibrational temperature of N2(C,v) (7000–10 000 K) and the excitation temperatures of N2(C) and N2(B) (11 000 K). The analysis of the H β line-width gives an upper limiting value of 1013 cm‑3 for the electron density; its axial variation (4  ×  1011–6  ×  1012 cm‑3) being estimated by solving the wave electrodynamics equations for the present geometry, plasma length and electron–neutral collision frequency. The experimental results were compared with the results from a 0D model, presented in companion paper I [1], which couples the system of rate balance equations for the dominant neutral and charged plasma species to the homogeneous two-term electron Boltzmann equation, taking the measured gas temperature and the estimated electron density as input parameters. Good qualitative agreement is found between the measurements and calculations of the local species densities for various powers and axial positions. The dissociation degree of oxygen is found above 10%. Moreover, both the measurements and calculations show evidence of the non-equilibrium behavior of low-temperature plasmas, with vibrational and excitation

  16. A radial differential mobility analyzer for the size-classification of gas-phase synthesized nanoparticles at low pressures

    NASA Astrophysics Data System (ADS)

    Nanda, K. K.; Kruis, F. E.

    2014-07-01

    Differential mobility analyzers (DMAs) are commonly used to generate monodisperse nanoparticle aerosols. Commercial DMAs operate at quasi-atmospheric pressures and are therefore not designed to be vacuum-tight. In certain particle synthesis methods, the use of a vacuum-compatible DMA is a requirement as a process step for producing high-purity metallic particles. A vacuum-tight radial DMA (RDMA) has been developed and tested at low pressures. Its performance has been evaluated by using a commercial NANO-DMA as the reference. The performance of this low-pressure RDMA (LP-RDMA) in terms of the width of its transfer function is found to be comparable with that of other NANO-DMAs at atmospheric pressure and is almost independent of the pressure down to 30 mbar. It is shown that LP-RDMA can be used for the classification of nanometer-sized particles (5-20 nm) under low pressure condition (30 mbar) and has been successfully applied to nanoparticles produced by ablating FeNi at low pressures.

  17. Differential Exposure to Hazardous Air Pollution in the United States: A Multilevel Analysis of Urbanization and Neighborhood Socioeconomic Deprivation

    PubMed Central

    Young, Gary S.; Fox, Mary A.; Trush, Michael; Kanarek, Norma; Glass, Thomas A.; Curriero, Frank C.

    2012-01-01

    Population exposure to multiple chemicals in air presents significant challenges for environmental public health. Air quality regulations distinguish criteria air pollutants (CAPs) (e.g., ozone, PM2.5) from hazardous air pollutants (HAPs)—187 chemicals which include carcinogens and others that are associated with respiratory, cardiovascular, neurological and numerous other non-cancer health effects. Evidence of the public’s cumulative exposure and the health effects of HAPs are quite limited. A multilevel model is used to assess differential exposure to HAP respiratory, neurological, and cancer hazards (2005) related to the Townsend Index of Socioeconomic Deprivation (TSI), after adjustment for regional population size and economic activity, and local population density. We found significant positive associations between tract TSI and respiratory and cancer HAP exposure hazards, and smaller effects for neurological HAPs. Tracts in the top quintile of TSI have between 38%–60% higher HAP exposure than the bottom quintile; increasing population size from the bottom quintile to the top quintile modifies HAP exposure hazard related to TSI, increasing cancer HAP exposure hazard by 6% to 20% and increasing respiratory HAP exposure hazard by 12% to 27%. This study demonstrates the value of social epidemiological methods for analyzing differential exposure and advancing cumulative risk assessment. PMID:22829799

  18. Explosion bomb measurements of ethanol-air laminar gaseous flame characteristics at pressures up to 1.4 MPa

    SciTech Connect

    Bradley, D.; Lawes, M.; Mansour, M.S.

    2009-07-15

    The principal burning characteristics of a laminar flame comprise the fuel vapour pressure, the laminar burning velocity, ignition delay times, Markstein numbers for strain rate and curvature, the stretch rates for the onset of flame instabilities and of flame extinction for different mixtures. With the exception of ignition delay times, measurements of these are reported and discussed for ethanol-air mixtures. The measurements were in a spherical explosion bomb, with central ignition, in the regime of a developed stable, flame between that of an under or over-driven ignition and that of an unstable flame. Pressures ranged from 0.1 to 1.4 MPa, temperatures from 300 to 393 K, and equivalence ratios were between 0.7 and 1.5. It was important to ensure the relatively large volume of ethanol in rich mixtures at high pressures was fully evaporated. The maximum pressure for the measurements was the highest compatible with the maximum safe working pressure of the bomb. Many of the flames soon became unstable, due to Darrieus-Landau and thermo-diffusive instabilities. This effect increased with pressure and the flame wrinkling arising from the instabilities enhanced the flame speed. Both the critical Peclet number and the, more rational, associated critical Karlovitz stretch factor were evaluated at the onset of the instability. With increasing pressure, the onset of flame instability occurred earlier. The measured values of burning velocity are expressed in terms of their variations with temperature and pressure, and these are compared with those obtained by other researchers. Some comparisons are made with the corresponding properties for iso-octane-air mixtures. (author)

  19. Air Pressure, Humidity and Stroke Occurrence: A Systematic Review and Meta-Analysis

    PubMed Central

    Cao, Yongjun; Wang, Xia; Zheng, Danni; Robinson, Thompson; Hong, Daqing; Richtering, Sarah; Leong, Tzen Hugh; Salam, Abdul; Anderson, Craig; Hackett, Maree L.

    2016-01-01

    Background/Aims: An influence of climate upon stroke risk is biologically plausible and supported by epidemiological evidence. We aimed to determine whether air pressure (AP) and humidity are associated with hospital stroke admission. Methods: We searched MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify relevant population-based observational studies. Where possible, data were pooled for meta-analysis with odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random-effect method. Results: We included 11 studies with a total of 314,385 patients. The effect of AP was varied across studies for ischemic stroke (IS) and subarachnoid haemorrhage (SAH). Pooled ORs (95%CI) associated with 1 hPa increase in AP for the risk of IS, intracerebral hemorrhage (ICH) and SAH were 1.00 (0.99–1.01), 1.01 (0.99–1.02) and 1.02 (0.97–1.07) respectively. The pooled ORs (95%CI) associated with 1 percent increase in humidity for the risk of IS and ICH were 1.00 (1.00–1.01) and 1.00 (0.99–1.01) respectively. Conclusion: This review shows that there is no evidence of a relationship between AP or humidity and the occurrence of hospital admission for stroke. Further research is needed to clarify the extent and nature of any relationship between AP, humidity and stroke in different geographical areas. PMID:27399733

  20. Soot Formation in Laminar Premixed Ethylene/Air Flames at Atmospheric Pressure. Appendix G

    NASA Technical Reports Server (NTRS)

    Xu, F.; Sunderland, P. B.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

    2001-01-01

    Soot formation was studied within laminar premixed ethylene/air flames (C/O ratios of 0.78-0.98) stabilized on a flat-flame burner operating at atmospheric pressure. Measurements included soot volume fractions by both laser extinction and gravimetric methods, temperatures by multiline emission, soot structure by thermophoretic sampling and transmission electron microscopy, major gas species concentrations by sampling and gas chromatography, concentrations of condensable hydrocarbons by gravimetric sampling. and velocities by laser velocimetry. These data were used to find soot surface growth rates and primary soot particle nucleation rates along the axes of the flames. Present measurements of soot surface growth rates were correlated successfully by predictions based on typical hydrogen-abstraction/carbon-addition (HACA) mechanisms of Frenklach and co-workers and Colket and Hall. These results suavest that reduced soot surface growth rates with increasing residence time seen in the present and other similar flames were mainly caused by reduced rates of surface activation due to reduced H atom concentrations as temperatures decrease as a result of radiative heat losses. Primary soot particle nucleation rates exhibited variations with temperature and acetylene concentrations that were similar to recent observations for diffusion flames; however, nucleation rates in the premixed flames were significantly lower than in, the diffusion flames for reasons that still must be explained. Finally, predictions of yields of major gas species based on mechanisms from both Frenklach and co-workers and Leung and Lindstedt were in good agreement with present measurements and suggest that H atom concentrations (relevant to HACA mechanisms) approximate estimates based on local thermodynamic equilibrium in the present flames.

  1. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix J

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  2. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix C

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  3. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix H

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  4. High Pressure Air Jet in the Endoscopic Preparation Room: Risk of Noise Exposure on Occupational Health

    PubMed Central

    Lu, Lung-Sheng; Wu, Cheng-Kun

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment was taken during 7 automatic endoscopic reprocessors (AERs) and combined with/without HPAJ use over an 8-hour time-weighted average (TWA). Analytical procedures of the NIOSH and the ISO for noise-induced hearing loss were estimated to develop analytic models. The peak of the noise spectrum of combined HPAJ and 7 AERs was significantly higher than that of the 7 AERs alone (108.3 ± 1.36 versus 69.3 ± 3.93 dBA, P < 0.0001). The risk of hearing loss (HL > 2.5 dB) was 2.15% at 90 dBA, 11.6% at 95 dBA, and 51.3% at 100 dBA. The odds ratio was 49.1 (95% CI: 11.9 to 203.6). The noise generated by the HPAJ to work over TWA seriously affected the occupational health and safety of those working in an endoscopic preparation room. PMID:25710009

  5. Deactivating bacteria with RF Driven Hollow Slot Microplasmas in Open Air at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Yu, Zengqi; Pruden, Amy; Sharma, Ashish; Collins, George

    2003-10-01

    A hollow slot discharge operating in open air at atmospheric pressure has demonstrated its ability to deactivate bacterial growth on nearby surfaces exposed to the RF driven plasma. The cold plasma exits from a hollow slot with a width of 0.2 mm and variable length of 1-35 cm. An internal electrode was powered by 13.56 MHz radio-frequency power at a voltage below 200 V. External electrically grounded slots face the work piece. The plasma plume extends millimeters to centimeter beyond the hollow slot toward the work piece to be irradiated. Argon-Oxygen gas mixtures, at 33 liters per minute flow, were passed through the electrodes and the downstream plasma was employed for the process, with treatment exposure time varied from 0.06 to 0.18 seconds. Bacterial cultures were fixed to 0.22 micron cellulose filter membranes and passed under the plasma at a controlled rate at a distance of about 5-10 millimeters from the grounded slot electrode. Preliminary studies on the effectiveness of the plasma for sterilization were carried out on E. coli. Cultures were grown overnight on the membranes after exposure and the resulting colony forming units (cfu) were determined in treated and untreated groups. In the plasma treated group, a 98.2% kill rate was observed with the lowest exposure time, and increased to 99.8% when the exposure time was tripled. These studies clearly demonstrate the ability of the RF-driven hollow slot atmospheric plasma to inhibit bacterial growth on surfaces.

  6. Inhibitory effect of silver nanoparticles mediated by atmospheric pressure air cold plasma jet against dermatophyte fungi.

    PubMed

    Ouf, Salama A; El-Adly, Amira A; Mohamed, Abdel-Aleam H

    2015-10-01

    In an in vitro study with five clinical isolates of dermatophytes, the MIC(50) and MIC(100) values of silver nanoparticles (AgNPs) ranged from 5 to 16 and from 15 to 32 μg ml(- 1), respectively. The combined treatment of AgNPs with atmospheric pressure-air cold plasma (APACP) induced a drop in the MIC(50) and MIC100 values of AgNPs reaching 3-11 and 12-23 μg ml(- 1), respectively, according to the examined species. Epidermophyton floccosum was the most sensitive fungus to AgNPs, while Trichophyton rubrum was the most tolerant. AgNPs induced significant reduction in keratinase activity and an increase in the mycelium permeability that was greater when applied combined with plasma treatment. Scanning electron microscopy showed electroporation of the cell walls and the accumulation of AgNPs on the cell wall and inside the cells, particularly when AgNPs were combined with APACP treatment. An in vivo experiment with dermatophyte-inoculated guinea pigs indicated that the application of AgNPs combined with APACP was more efficacious in healing and suppressing disease symptoms of skin as compared with the application of AgNPs alone. The recovery from the infection reached 91.7 % in the case of Microsporum canis-inoculated guinea pigs treated with 13 μg ml(- 1) AgNPs combined with APACP treatment delivered for 2  min. The emission spectra indicated that the efficacy of APACP was mainly due to generation of NO radicals and excited nitrogen molecules. These reactive species interact and block the activity of the fungal spores in vitro and in the skin lesions of the guinea pigs. The results achieved are promising compared with fluconazole as reference antifungal drug. PMID:26296782

  7. Microwave plasma source operating with atmospheric pressure air-water mixtures

    NASA Astrophysics Data System (ADS)

    Tatarova, E.; Henriques, J. P.; Felizardo, E.; Lino da Silva, M.; Ferreira, C. M.; Gordiets, B.

    2012-11-01

    The overall performance of a surface wave driven air-water plasma source operating at atmospheric pressure and 2.45 GHz has been analyzed. A 1D model previously developed has been improved in order to describe in detail the creation and loss processes of active species of interest. This model provides a complete characterization of the axial structure of the source, including the discharge and the afterglow zones. The main electron creation channel was found to be the associative ionization process N + O → NO+ + e. The NO(X) relative density in the afterglow plasma jet ranges from 1.2% to 1.6% depending on power and water percentage, according to the model predictions and the measurements. Other types of species such as NO2 and nitrous acid HNO2 have also been detected by mass and Fourier Transform Infrared spectroscopy. The relative population density of O(3P) ground state atoms increases from 8% to 10% in the discharge zone when the input microwave power increases from 200 to 400 W and the water percentage from 1% to 10%. Furthermore, high densities of O2(a1Δg) singlet delta oxygen molecules and OH radicals (1% and 5%, respectively) can be achieved in the discharge zone. In the late afterglow the O2(a1Δg) density is about 0.1% of the total density. This plasma source has a flexible operation and potential for channeling the energy in ways that maximize the density of active species of interest.

  8. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    SciTech Connect

    Begum, Asma; Laroussi, Mounir; Pervez, Mohammad Rasel

    2013-06-15

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

  9. Long-Term Urban Particulate Air Pollution, Traffic Noise, and Arterial Blood Pressure

    PubMed Central

    Moebus, Susanne; Hertel, Sabine; Viehmann, Anja; Nonnemacher, Michael; Dragano, Nico; Möhlenkamp, Stefan; Jakobs, Hermann; Kessler, Christoph; Erbel, Raimund; Hoffmann, Barbara

    2011-01-01

    Background: Recent studies have shown an association of short-term exposure to fine particulate matter (PM) with transient increases in blood pressure (BP), but it is unclear whether long-term exposure has an effect on arterial BP and hypertension. Objectives: We investigated the cross-sectional association of residential long-term PM exposure with arterial BP and hypertension, taking short-term variations of PM and long-term road traffic noise exposure into account. Methods: We used baseline data (2000–2003) on 4,291 participants, 45–75 years of age, from the Heinz Nixdorf Recall Study, a population-based prospective cohort in Germany. Urban background exposure to PM with aerodynamic diameter ≤ 2.5 μm (PM2.5) and ≤ 10 μm (PM10) was assessed with a dispersion and chemistry transport model. We used generalized additive models, adjusting for short-term PM, meteorology, traffic proximity, and individual risk factors. Results: An interquartile increase in PM2.5 (2.4 μg/m3) was associated with estimated increases in mean systolic and diastolic BP of 1.4 mmHg [95% confidence interval (CI): 0.5, 2.3] and 0.9 mmHg (95% CI: 0.4, 1.4), respectively. The observed relationship was independent of long-term exposure to road traffic noise and robust to the inclusion of many potential confounders. Residential proximity to high traffic and traffic noise exposure showed a tendency toward higher BP and an elevated prevalence of hypertension. Conclusions: We found an association of long-term exposure to PM with increased arterial BP in a population-based sample. This finding supports our hypothesis that long-term PM exposure may promote atherosclerosis, with air-pollution–induced increases in BP being one possible biological pathway. PMID:21827977

  10. Inhibitory effect of silver nanoparticles mediated by atmospheric pressure air cold plasma jet against dermatophyte fungi.

    PubMed

    Ouf, Salama A; El-Adly, Amira A; Mohamed, Abdel-Aleam H

    2015-10-01

    In an in vitro study with five clinical isolates of dermatophytes, the MIC(50) and MIC(100) values of silver nanoparticles (AgNPs) ranged from 5 to 16 and from 15 to 32 μg ml(- 1), respectively. The combined treatment of AgNPs with atmospheric pressure-air cold plasma (APACP) induced a drop in the MIC(50) and MIC100 values of AgNPs reaching 3-11 and 12-23 μg ml(- 1), respectively, according to the examined species. Epidermophyton floccosum was the most sensitive fungus to AgNPs, while Trichophyton rubrum was the most tolerant. AgNPs induced significant reduction in keratinase activity and an increase in the mycelium permeability that was greater when applied combined with plasma treatment. Scanning electron microscopy showed electroporation of the cell walls and the accumulation of AgNPs on the cell wall and inside the cells, particularly when AgNPs were combined with APACP treatment. An in vivo experiment with dermatophyte-inoculated guinea pigs indicated that the application of AgNPs combined with APACP was more efficacious in healing and suppressing disease symptoms of skin as compared with the application of AgNPs alone. The recovery from the infection reached 91.7 % in the case of Microsporum canis-inoculated guinea pigs treated with 13 μg ml(- 1) AgNPs combined with APACP treatment delivered for 2  min. The emission spectra indicated that the efficacy of APACP was mainly due to generation of NO radicals and excited nitrogen molecules. These reactive species interact and block the activity of the fungal spores in vitro and in the skin lesions of the guinea pigs. The results achieved are promising compared with fluconazole as reference antifungal drug.

  11. Liquid Steel at Low Pressure: Experimental Investigation of a Downward Water Air Flow

    NASA Astrophysics Data System (ADS)

    Thumfart, Maria

    2016-07-01

    In the continuous casting of steel controlling the steel flow rate to the mould is critical because a well-defined flow field at the mould level is essential for a good quality of the cast product. The stopper rod is a commonly used device to control this flow rate. Agglomeration of solid material near the stopper rod can lead to a reduced cross section and thus to a decreased casting speed or even total blockage (“clogging”). The mechanisms causing clogging are still not fully understood. Single phase considerations of the flow in the region of the stopper rod result in a low or even negative pressure at the smallest cross section. This can cause degassing of dissolved gases from the melt, evaporation of alloys and entrainment of air through the porous refractory material. It can be shown that the degassing process in liquid steel is taking place mainly at the stopper rod tip and its surrounding. The steel flow around the stopper rod tip is highly turbulent. In addition refractory material has a low wettability to liquid steel. So the first step to understand the flow situation and transport phenomena which occur near the stopper is to understand the behaviour of this two phase (steel, gas) flow. To simulate the flow situation near the stopper rod tip, water experiments are conducted using a convergent divergent nozzle with three different wall materials and three different contact angles respectively. These experiments show the high impact of the wettability of the wall material on the actual flow structure at a constant gas flow rate.

  12. Experimental and predicted pressure and heating distributions for an Aeroassist Flight Experiment vehicle in air at Mach 10

    NASA Technical Reports Server (NTRS)

    Micol, John R.

    1989-01-01

    The Aeroassisted Flight Experiment vehicle for whose scale model pressure and heat-transfer rate distributions have been measured in air at Mach 10 is a 60-deg elliptic cone, raked off at a 73-percent angle, with an ellipsoid nose and a skirt added to the base of the rake plane to reduce heating. The predictions of both an inviscid flow-field code and a Navier-Stokes solver are compared with measured values. Good agreement is obtained in the case of pressure distributions; the effect of Reynolds number on heat-transfer distributions is noted to be small.

  13. Effects of surface pressure on the properties of Langmuir monolayers and interfacial water at the air-water interface.

    PubMed

    Lin, Wei; Clark, Anthony J; Paesani, Francesco

    2015-02-24

    The effects of surface pressure on the physical properties of Langmuir monolayers of palmitic acid (PA) and dipalmitoylphosphatidic acid (DPPA) at the air/water interface are investigated through molecular dynamics simulations with atomistic force fields. The structure and dynamics of both monolayers and interfacial water are compared across the range of surface pressures at which stable monolayers can form. For PA monolayers at T = 300 K, the untilted condensed phase with a hexagonal lattice structure is found at high surface pressure, while the uniformly tilted condensed phase with a centered rectangular lattice structure is observed at low surface pressure, in agreement with the available experimental data. A state with uniform chain tilt but no periodic spatial ordering is observed for DPPA monolayers on a Na(+)/water subphase at both high and low surface pressures. The hydrophobic acyl chains of both monolayers pack efficiently at all surface pressures, resulting in a very small number of gauche defects. The analysis of the hydrogen-bonding structure/dynamics at the monolayer/water interface indicates that water molecules hydrogen-bonded to the DPPA head groups reorient more slowly than those hydrogen-bonded to the PA head groups, with the orientational dynamics becoming significantly slower at high surface pressure. Possible implications for physicochemical processes taking place on marine aerosols in the atmosphere are discussed.

  14. Inactivation of Escherichia coli Cells in Aqueous Solution by Atmospheric-Pressure N2, He, Air, and O2 Microplasmas

    PubMed Central

    Zhou, Renwu; Zhang, Xianhui; Bi, Zhenhua; Zong, Zichao; Niu, Jinhai; Song, Ying; Yang, Size

    2015-01-01

    Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to inactivate Escherichia coli cells suspended in aqueous solution. Measurements show that the efficiency of inactivation of E. coli cells is strongly dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2 and He microplasma arrays, air and O2 microplasma arrays may be utilized to more efficiently kill E. coli cells in aqueous solution. The efficiencies of inactivation of E. coli cells in water can be well described by using the chemical reaction rate model, where reactive oxygen species play a crucial role in the inactivation process. Analysis indicates that plasma-generated reactive species can react with E. coli cells in water by direct or indirect interactions. PMID:26025895

  15. Motor control of sound frequency in birdsong involves the interaction between air sac pressure and labial tension

    NASA Astrophysics Data System (ADS)

    Alonso, Rodrigo; Goller, Franz; Mindlin, Gabriel B.

    2014-03-01

    Frequency modulation is a salient acoustic feature of birdsong. Its control is usually attributed to the activity of syringeal muscles, which affect the tension of the labia responsible for sound production. We use experimental and theoretical tools to test the hypothesis that for birds producing tonal sounds such as domestic canaries (Serinus canaria), frequency modulation is determined by both the syringeal tension and the air sac pressure. For different models, we describe the structure of the isofrequency curves, which are sets of parameters leading to sounds presenting the same fundamental frequencies. We show how their shapes determine the relative roles of syringeal tension and air sac pressure in frequency modulation. Finally, we report experiments that allow us to unveil the features of the isofrequency curves.

  16. Inactivation of Escherichia coli Cells in Aqueous Solution by Atmospheric-Pressure N2, He, Air, and O2 Microplasmas.

    PubMed

    Zhou, Renwu; Zhang, Xianhui; Bi, Zhenhua; Zong, Zichao; Niu, Jinhai; Song, Ying; Liu, Dongping; Yang, Size

    2015-08-01

    Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to inactivate Escherichia coli cells suspended in aqueous solution. Measurements show that the efficiency of inactivation of E. coli cells is strongly dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2 and He microplasma arrays, air and O2 microplasma arrays may be utilized to more efficiently kill E. coli cells in aqueous solution. The efficiencies of inactivation of E. coli cells in water can be well described by using the chemical reaction rate model, where reactive oxygen species play a crucial role in the inactivation process. Analysis indicates that plasma-generated reactive species can react with E. coli cells in water by direct or indirect interactions.

  17. Long-term ambient air pollution exposure and risk of high blood pressure among citizens in Nis, Serbia.

    PubMed

    Stanković, Aleksandra; Nikolić, Maja

    2016-01-01

    Epidemiological studies suggest that long-term exposure to air pollution increases the risk for high blood pressure (BP). The aim of our study is to evaluate any effects in BP in citizens exposed to long-term ambient air pollution. The subjects are 1136 citizens, aged 18-70 years, living for more than 5 years in the same home in the areas with a different level of air pollution. The air concentrations of black smoke and sulfur dioxide were determined in the period from 2001 to 2011. We measured systolic and diastolic BP and heart rate. Multivariate methods were used in the analysis. Alcohol consumption had the greatest influence on the incidence of hypertension as a risk factor (RR: 3.461; 95% CI: 1.72-6.93) and age had the least (RR: 1.23; 95% CI: 1.183-1.92). Exposure to air pollution increases risk for developing hypertension 2.5 times (95% CI: 1.46-4.49). Physical activity has proved to be statistically significant protective factor for the development of hypertension. Long-term exposure to low levels of main air pollutants is significantly associated with elevated risk of hypertension.

  18. Influence of the voltage polarity on the properties of a nanosecond surface barrier discharge in atmospheric-pressure air

    SciTech Connect

    Nudnova, M. M.; Aleksandrov, N. L.; Starikovskii, A. Yu.

    2010-01-15

    The properties of a surface barrier discharge in atmospheric-pressure air at different polarities of applied voltage were studied experimentally. The influence of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.

  19. Experimental study of the effect of drag reducing agent on pressure drop and thermal efficiency of an air cooler

    NASA Astrophysics Data System (ADS)

    Peyghambarzadeh, S. M.; Hashemabadi, S. H.; Saffarian, H.; Shekari, F.

    2016-01-01

    Effect of polymeric drag reduction agents (DRAs) on pressure drop and heat transfer was studied. Aqueous solutions of carboxy methyl cellulose were used inside an air-finned heat exchanger. Despite the previous studies which indicated the importance of drag reduction just in turbulent flow, results of this study in laminar flow indicated that the addition of DRA increases drag reduction, and decreases the overall heat transfer coefficient.

  20. A one-dimensional numerical model for predicting pressure and velocity oscillations of a compressed air-pocket in a vertical shaft

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Leon, A.; Apte, S.

    2015-12-01

    The presence of pressurized air pockets in combined sewer systems is argued to produce geyser flows, which is an oscillating jetting of a mixture of gas-liquid flows through vertical shafts. A 1D numerical model is developed for predicting pressure and velocity oscillations of a compressed air-pocket in a vertical shaft which in turn attempts to simulate geyser like flows. The vertical shaft is closed at the bottom and open to ambient pressure at the top. Initially, the lower section of the vertical shaft is filled with compressed air and the upper section with water. The interaction between the pressurized air pocket and the water column in the vertical shaft exhibits an oscillatory motion of the water column that decays over time. The model accounts for steady and unsteady friction to estimate the energy dissipation. The model also includes the falling flow of water around the external perimeter of the pressurized air pocket by assuming that any expansion in the pressurized air pocket would result in the falling volume of water. The acceleration of air-water interface is predicted through a force balance between the pressurized air pocket and the water column combined with the Method of Characteristics that resolves pressure and velocity within the water column. The expansion and compression of the pressurized air pocket is assumed to follow either isothermal process or adiabatic process. Results for both assumptions; isothermal and adiabatic processes, are presented. The performance of the developed 1D numerical model is compared with that of a commercial 3D CFD model. Overall, a good agreement between both models is obtained for pressure and velocity oscillations. The paper will also present a sensitivity analysis of the 3D CFD model.

  1. Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

    ERIC Educational Resources Information Center

    Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

    2005-01-01

    The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

  2. Human activity under high pressure: A case study on fluctuation scaling of air traffic controller's communication behaviors

    NASA Astrophysics Data System (ADS)

    Wang, Yanjun; Zhang, Qiqian; Zhu, Chenping; Hu, Minghua; Duong, Vu

    2016-01-01

    Recent human dynamics research has unmasked astonishing statistical characteristics such as scaling behaviors in human daily activities. However, less is known about the general mechanism that governs the task-specific activities. In particular, whether scaling law exists in human activities under high pressure remains an open question. In air traffic management system, safety is the most important factor to be concerned by air traffic controllers who always work under high pressure, which provides a unique platform to study human activity. Here we extend fluctuation scaling method to study air traffic controller's communication activity by investigating two empirical communication datasets. Taken the number of controlled flights as the size-like parameter, we show that the relationships between the average communication activity and its standard deviation in both datasets can be well described by Taylor's power law, with scaling exponent α ≈ 0.77 ± 0.01 for the real operational data and α ≈ 0.54 ± 0.01 for the real-time training data. The difference between the exponents suggests that human dynamics under pressure is more likely dominated by the exogenous force. Our findings may lead to further understanding of human behavior.

  3. Pressurized liquid extraction of diesel and air particulate standard reference materials: effect of extraction temperature and pressure.

    PubMed

    Schantz, Michele M; McGaw, Elizabeth; Wise, Stephen A

    2012-10-01

    Four particulate matter Standard Reference Materials (SRMs) available from the National Institute of Standards and Technology (NIST) were used to evaluate the effect of solvent, number of static cycles and static times, pressure, and temperature when using pressurized liquid extraction (PLE) for the extraction of polycyclic aromatic hydrocarbons (PAHs) and nitrated-PAHs. The four materials used in the study were SRM 1648a Urban Particulate Matter, SRM 1649b Urban Dust, SRM 1650b Diesel Particulate Matter, and SRM 2975 Diesel Particulate Matter (Industrial Forklift). The results from the study indicate that the choice of solvent, dichloromethane compared to toluene and toluene/methanol mixtures, had little effect on the extraction efficiency. With three to five extraction cycles, increasing the extraction time for each cycle from 5 to 30 min had no significant effect on the extraction efficiency. The differences in extraction efficiency were not significant (with over 95% of the differences being <10%) when the pressure was increased from 13.8 to 20.7 MPa. The largest increase in extraction efficiency occurred for selected PAHs when the temperature of extraction was increased from 100 to 200 °C. At 200 °C naphthalene, biphenyl, fluorene, dibenzothiophene, and anthracene show substantially higher mass fractions (>30%) than when extracted at 100 °C in all the SRMs studied. For SRM 2975, large increases (>100%) are also observed for some other PAHs including benz[a]anthracene, benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, benzo[ghi]perylene, and benzo[b]chrysene when extracted at the higher temperatures; however, similar trends were not observed for the other diesel particulate sample, SRM 1650b. The results are discussed in relation to the use of the SRMs for evaluating analytical methods.

  4. Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers

    SciTech Connect

    Lee, Eun J.; Oh, Sang Youp; Kim, Ho Y.; Yoon, Sam S.; James, Scott C.

    2010-11-15

    Because of thermal fluid-property dependence, atomization stability (or flow regime) can change even at fixed operating conditions when subject to temperature change. Particularly at low temperatures, fuel's high viscosity can prevent a pressure-swirl (or simplex) atomizer from sustaining a centrifugal-driven air core within the fuel injector. During disruption of the air core inside an injector, spray characteristics outside the nozzle reflect a highly unstable, nonlinear mode where air core length, Sauter mean diameter (SMD), cone angle, and discharge coefficient variability. To better understand injector performance, these characteristics of the pressure-swirl atomizer were experimentally investigated and data were correlated to Reynolds numbers (Re). Using a transparent acrylic nozzle, the air core length, SMD, cone angle, and discharge coefficient are observed as a function of Re. The critical Reynolds numbers that distinguish the transition from unstable mode to transitional mode and eventually to a stable mode are reported. The working fluids are diesel and a kerosene-based fuel, referred to as bunker-A. (author)

  5. Effects of 6-h exposure to low relative humidity and low air pressure on body fluid loss and blood viscosity.

    PubMed

    Hashiguchi, N; Takeda, A; Yasuyama, Y; Chishaki, A; Tochihara, Y

    2013-10-01

    The purpose of this study was to investigate the effects of 6-h exposure to low relative humidity (RH) and low air pressure in a simulated air cabin environment on body fluid loss (BFL) and blood viscosity. Fourteen young healthy male subjects were exposed to four conditions, which combined RH (10% RH or 60% RH) and air pressure (NP: sea level or LP: equivalent to an altitude of 2000 m). Subjects remained seated on a chair in the chamber for 6 h. Their diet and water intake were restricted before and during the experiment. Insensible water loss (IWL) in LP10% condition was significantly greater than in NP60% condition; thus, combined 10%RH and LP conditions promoted a greater amount of IWL. The BFL under the LP condition was significantly greater than that under the NP condition. Blood viscosity significantly increased under LP conditions. Increases in red blood cell counts (RBCs) and BFL likely contributed to the increased blood viscosity. These findings suggest that hypobaric-induced hypoxia, similar to the conditions in the air cabin environment, may cause increased blood viscosity and that the combined low humidity and hypobaric hypoxia conditions increase IWL. PMID:23464811

  6. Extinction of Lean Near-Limit Methane/Air Flames at Elevated Pressures under Normal- and Micro-Gravity

    SciTech Connect

    Zhang, H.; Fan, R.; Wang, S.; Tian, X.; Xu, K.; Wan, S.; Egolfopoulos, Fokion N.

    2011-01-01

    The extinction limits of lean, near-limit, counterflowing, CH{sub 4}/air twin premixed flames were studied experimentally at evaluated pressures and under normal- and micro-gravity conditions utilizing the 3.5 s drop tower of the National Microgravity Laboratory of China. The results showed that under micro-gravity conditions the natural convection is minimized and the flames become more planar and symmetric compared to normal gravity. In both normal- and micro-gravity experiments and for a given strain rate and fuel concentration, the flame luminosity was found to enhance as the pressure increases. On the other hand, at a given pressure, the flame luminosity was determined to weaken as the strain rate decreases. At a given strain rate, the fuel concentration at extinction was found to vary non-monotonically with pressure, namely it first increases and subsequently decreases with pressure. The limit fuel concentration peaks around 3 and 4 atm under normal- and micro-gravity, respectively. The extinction limits measured at micro-gravity were in good agreement with predictions obtained through detailed numerical simulations but they are notably lower compared to the data obtained under normal gravity. The simulations confirmed the non-monotonic variation of flammability limits with pressure, in agreement with previous studies. Sensitivity analysis showed that for pressures between one and 5 atm, the near-limit flame response is dominated by the competition between the main branching, H + O{sub 2} → OH + O, and the pressure sensitive termination, H + O{sub 2} + M → HO{sub 2} + M, reaction. However, for pressures greater than 5 atm it was determined that the HO{sub 2} kinetics result in further chain branching in a way that is analogous to the third explosion limit of H{sub 2}/O{sub 2} mixtures.

  7. Ionic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Colas, Dorian F.; Ferret, Antoine; Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-11-01

    A wire-cylinder-plate electrode configuration is presented to generate ionic wind with a dc corona discharge in air at atmospheric pressure. The objective of the work is to maximize the power supplied to the flow in order to increase acceleration while avoiding breakdown. Thus, the proposed experimental setup addresses the problem of decoupling the mechanism of ion generation from that of ion acceleration. Using a wire-plate configuration as a reference, we have focused on improving the topography of the electric field to (1) separate the ionization and acceleration zones in space, and (2) guide the trajectory of charged particles as parallel to the median axis as possible. In the proposed wire-cylinder-plate setup, a dc corona discharge is generated in the space between a wire and two cylinders. The ions produced by the corona then drift past the cylinders and into a channel between two plates, where they undergo acceleration. To maximize the ionic wind it is found that the geometric configuration must be as compact as possible and that the voltage applied must be right below breakdown. Experimentally, the optimized wire-plate reference setup provides a maximum flow velocity of 8 m s-1, a flow rate per unit electrode length of 0.034 m2 s-1, and a thrust per unit electrode length of 0.24 N m-1. The wire-cylinder-plate configuration provides a maximum flow velocity of 10 m s-1, a flow rate per unit electrode length of 0.041 m2 s-1, and a thrust per unit electrode length of 0.35 N m-1. This 46% increase in thrust is obtained by increasing the electric power per unit electrode length by only 16% (from 175 to 210 W m-1), which confirms the gain in efficiency obtained with the decoupled system. In comparison with a simple wire-wire corona configuration, the wire-cylinder-plate configuration increases the ionic wind velocity by up to a factor of 3, and the thrust by an order of magnitude.

  8. Use of pressure in reversed-phase liquid chromatography to study protein conformational changes by differential deuterium exchange.

    PubMed

    Makarov, Alexey A; Schafer, Wes A; Helmy, Roy

    2015-02-17

    The market of protein therapeutics is exploding, and characterization methods for proteins are being further developed to understand and explore conformational structures with regards to function and activity. There are several spectroscopic techniques that allow for analyzing protein secondary structure in solution. However, a majority of these techniques need to use purified protein, concentrated enough in the solution to produce a relevant spectrum. In this study, we describe a novel approach which uses ultrahigh pressure liquid chromatography (UHPLC) coupled with mass-spectrometry (MS) to explore compressibility of the secondary structure of proteins under increasing pressure detected by hydrogen-deuterium exchange (HDX). Several model proteins were used for these studies. The studies were conducted with UHPLC in isocratic mode at constant flow rate and temperature. The pressure was modified by a backpressure regulator up to about 1200 bar. It was found that the increase of retention factors upon pressure increase, at constant flow rate and temperature, was based on reduction of the proteins' molecular molar volume. The change in the proteins' molecular molar volume was caused by changes in protein folding, as was revealed by differential deuterium exchange. The degree of protein folding under certain UHPLC conditions can be controlled by pressure, at constant temperature and flow rate. By modifying pressure during UHPLC separation, it was possible to achieve changes in protein folding, which were manifested as changes in the number of labile protons exchanged to deuterons, or vice versa. Moreover, it was demonstrated with bovine insulin that a small difference in the number of protons exchanged to deuterons (based on protein folding under pressure) could be observed between batches obtained from different sources. The use of HDX during UHPLC separation allowed one to examine protein folding by pressure at constant flow rate and temperature in a mixture of

  9. Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels

    NASA Astrophysics Data System (ADS)

    Som, Sanjoy M.; Buick, Roger; Hagadorn, James W.; Blake, Tim S.; Perreault, John M.; Harnmeijer, Jelte P.; Catling, David C.

    2016-06-01

    How the Earth stayed warm several billion years ago when the Sun was considerably fainter is the long-standing problem of the `faint young Sun paradox'. Because of negligible O2 and only moderate CO2 levels in the Archaean atmosphere, methane has been invoked as an auxiliary greenhouse gas. Alternatively, pressure broadening in a thicker atmosphere with a N2 partial pressure around 1.6-2.4 bar could have enhanced the greenhouse effect. But fossilized raindrop imprints indicate that air pressure 2.7 billion years ago (Gyr) was below twice modern levels and probably below 1.1 bar, precluding such pressure enhancement. This result is supported by nitrogen and argon isotope studies of fluid inclusions in 3.0-3.5 Gyr rocks. Here, we calculate absolute Archaean barometric pressure using the size distribution of gas bubbles in basaltic lava flows that solidified at sea level ~2.7 Gyr in the Pilbara Craton, Australia. Our data indicate a surprisingly low surface atmospheric pressure of Patm = 0.23 +/- 0.23 (2σ) bar, and combined with previous studies suggests ~0.5 bar as an upper limit to late Archaean Patm. The result implies that the thin atmosphere was rich in auxiliary greenhouse gases and that Patm fluctuated over geologic time to a previously unrecognized extent.

  10. An Analytical Explanation for the X-43A Flush Air Data Sensing System Pressure Mismatch Between Flight and Theory

    NASA Technical Reports Server (NTRS)

    Ellsworth, Joel C.

    2010-01-01

    Following the successful Mach 7 flight test of the X-43A, unexpectedly low pressures were measured by the aft set of the onboard Flush Air Data Sensing System s pressure ports. These in-flight aft port readings were significantly lower below Mach 3.5 than was predicted by theory. The same lower readings were also seen in the Mach 10 flight of the X-43A and in wind-tunnel data. The pre-flight predictions were developed based on 2-dimensional wedge flow, which fails to predict some of the significant 3-dimensional flow features in this geometry at lower Mach numbers. Using Volterra s solution to the wave equation as a starting point, a three-dimensional finite wedge approximation to flow over the X-43A forebody is presented. The surface pressures from this approximation compare favorably with the measured wind tunnel and flight data at speeds of Mach 2.5 and 3.

  11. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    NASA Astrophysics Data System (ADS)

    Narayan, Jagdish; Bhaumik, Anagh

    2016-02-01

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  12. Decreasing the Limits of Detection and Analysis Time of Ion Current Rectification Biosensing Measurements via a Mechanically Applied Pressure Differential.

    PubMed

    Schibel, Anna E P; Ervin, Eric N

    2015-07-01

    Improving on the analytical capabilities of a measurement is a fundamental challenge with all assays, particularly decreasing the limit of detection while maintaining a practical associated analysis time. Of late, ion current rectification (ICR) biosensing measurements have received a great deal of attention as an analyte-specific, label-free assay. In ICR biosensing, a nanopore coated with an analyte specific binding molecule (e.g., an antibody, an aptamer, etc.) is used to detect a target analyte based on the ability of the target analyte to alter the ICR response of the nanopore upon it binding to the aperture interior. This binding changes the local surface charge and/or size of the nanopore aperture, thus altering its ICR response in a time dependent manner. Here, we report the ability to enhance the transport of a target analyte molecule to and through the aperture of an antibody modified glass nanopore membrane (AMGNM) with the application of a mechanically applied pressure differential. We demonstrate that there is an optimal pressure that balances the flux of the target analyte through the AMGNM aperture with its ability to be bound and detected. Applying the optimal pressure differential allows for picomolar concentrations of the cleaved form of synaptosomal-associated protein 25 (cSNAP-25) to be detected within the same analysis time as micromolar concentrations detected without the use of the pressure differential. The methodology presented here significantly expands the utility of ICR biosensing measurements for detecting low-abundance biomolecules by lowering the limit of detection and reducing the associated analysis time. PMID:26043367

  13. Differential Susceptibility: The Genetic Moderation of Peer Pressure on Alcohol Use

    PubMed Central

    Cleveland, H. Harrington; Schlomer, Gabriel L.; Vandenbergh, David J.; Feinberg, Mark E.

    2016-01-01

    Although peer pressure can influence adolescents’ alcohol use, individual susceptibility to these pressures varies across individuals. The dopamine receptor D4 gene (DRD4) is a potential candidate gene that may influence adolescents’ susceptibility to their peer environment due to the role dopamine plays in reward sensation during social interaction. We hypothesized that DRD4 genotype status would moderate the impact of 7th-grade antisocial peer pressure on 12th-grade lifetime alcohol use (n = 414; 58.7 % female; 92.8 % White). The results revealed significant main effects for antisocial peer pressure, but no main effects for DRD4 genotype on lifetime alcohol use. Adolescent DRD4 genotype moderated the association between peer pressure and lifetime alcohol use. For individuals who carried at least one copy of the DRD4 7-repeat allele (7+), antisocial peer pressure was associated with increased lifetime alcohol use. These findings indicate that genetic sensitivity to peer pressure confers increased alcohol use in late adolescence. PMID:26307243

  14. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  15. Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

    2016-08-01

    This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

  16. A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: Measurement principle and static calibration

    NASA Astrophysics Data System (ADS)

    Saccomandi, Paola; Schena, Emiliano; Silvestri, Sergio

    2011-02-01

    An optoelectronic target-type volumetric air flow-rate transducer for bidirectional measurements is presented. The sensor is composed of a T-shaped target and two nominally identical LED-photodiode couples which are operated in differential mode. The sensitive surfaces of the photodiodes are differentially shadowed by the deflection of the target, which in turn depends on the gas flow-rate. The principle of operation is described in mathematical terms and the design parameters have been optimized in order to obtain the highest sensitivity along with minimal pressure drop and reduced dimensions. The sensor is placed in a 20 mm diameter hose and was tested with air flow-rate in the typical temperature range of mechanical ventilation between 20 and 40 °C. The theoretical model was validated through experiments carried out in the volumetric flow range from -7.0 to +7.0 l min-1. The nonlinear behavior allows sensitivities equal to 0.6 V l-1 min for flow rates ranging from -2.0 to +2.0 l min-1, equal to 2.0 V l-1 min for flow rates ranging from -3.0 to -2.0 l min-1 and from +2.0 to +3.0 l min-1, up to 5.7 V l-1 min at higher flow rates ranging from -7.0 to -3.0 l min-1 and from +3.0 to +7.0 l min-1. The linear range extends from 3.0 to 7.0 l min-1 with constant sensitivity equal to 5.7 V l-1 min. The sensor is able to detect a flow-rate equal to 1.0 l min-1 with a sensitivity of about 400 mV l-1 min. The differential nature of the output minimizes the influence of the LEDs' power supply variations and allows to obtain a repeatability in the order of 3% of full scale output. The small pressure drop produced by the sensor placed in-line the fluid stream, of about 2.4 Pa at 7 l min-1, corresponds to a negligible fluid dynamic resistance lower than 0.34 Pa l-1 min.

  17. A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: Measurement principle and static calibration

    SciTech Connect

    Saccomandi, Paola; Schena, Emiliano; Silvestri, Sergio

    2011-02-15

    An optoelectronic target-type volumetric air flow-rate transducer for bidirectional measurements is presented. The sensor is composed of a T-shaped target and two nominally identical LED-photodiode couples which are operated in differential mode. The sensitive surfaces of the photodiodes are differentially shadowed by the deflection of the target, which in turn depends on the gas flow-rate. The principle of operation is described in mathematical terms and the design parameters have been optimized in order to obtain the highest sensitivity along with minimal pressure drop and reduced dimensions. The sensor is placed in a 20 mm diameter hose and was tested with air flow-rate in the typical temperature range of mechanical ventilation between 20 and 40 deg. C. The theoretical model was validated through experiments carried out in the volumetric flow range from -7.0 to +7.0 l min{sup -1}. The nonlinear behavior allows sensitivities equal to 0.6 V l{sup -1} min for flow rates ranging from -2.0 to +2.0 l min{sup -1}, equal to 2.0 V l{sup -1} min for flow rates ranging from -3.0 to -2.0 l min{sup -1} and from +2.0 to +3.0 l min{sup -1}, up to 5.7 V l{sup -1} min at higher flow rates ranging from -7.0 to -3.0 l min{sup -1} and from +3.0 to +7.0 l min{sup -1}. The linear range extends from 3.0 to 7.0 l min{sup -1} with constant sensitivity equal to 5.7 V l{sup -1} min. The sensor is able to detect a flow-rate equal to 1.0 l min{sup -1} with a sensitivity of about 400 mV l{sup -1} min. The differential nature of the output minimizes the influence of the LEDs' power supply variations and allows to obtain a repeatability in the order of 3% of full scale output. The small pressure drop produced by the sensor placed in-line the fluid stream, of about 2.4 Pa at 7 l min{sup -1}, corresponds to a negligible fluid dynamic resistance lower than 0.34 Pa l{sup -1} min.

  18. Measurement of Pressure Dependent Fluorescence Yield of Air: Calibration Factor for UHECR Detectors

    SciTech Connect

    Belz, J.W.; Burt, G.W.; Cao, Z.; Chang, F.Y.; Chen, C.C.; Chen, C.W.; Chen, P.; Field, C.; Findlay, J.; Huntemeyer, Petra; Huang, M.A.; Hwang, W.-Y.P.; Iverson, R.; Jones, B.F.; Jui, C.C.H.; Kirn, M.; Lin, G.-L.; Loh, E.C.; Maestas, M.M.; Manago, N.; Martens, K.; /Montana U. /Utah U. /Taiwan, Natl. Taiwan U. /SLAC /Rutgers U., Piscataway

    2005-07-06

    In a test experiment at the Final Focus Test Beam of the Stanford Linear Accelerator Center, the fluorescence yield of 28.5 GeV electrons in air and nitrogen was measured. The measured photon yields between 300 and 400 nm at 1 atm and 29 C are Y(760 Torr){sup air} = 4.42 {+-} 0.73 and Y(760 Torr){sup N{sub 2}} = 29.2 {+-} 4.8 photons per electron per meter. Assuming that the fluorescence yield is proportional to the energy deposition of a charged particle traveling through air, good agreement with measurements at lower particle energies is observed.

  19. Lateral Line Layout Correlates with the Differential Hydrodynamic Pressure on Swimming Fish

    NASA Astrophysics Data System (ADS)

    Ristroph, Leif; Liao, James C.; Zhang, Jun

    2015-01-01

    The lateral line of fish includes the canal subsystem that detects hydrodynamic pressure gradients and is thought to be important in swimming behaviors such as rheotaxis and prey tracking. Here, we explore the hypothesis that this sensory system is concentrated at locations where changes in pressure are greatest during motion through water. Using high-fidelity models of rainbow trout, we mimic the flows encountered during swimming while measuring pressure with fine spatial and temporal resolution. The variations in pressure for perturbations in body orientation and for disturbances to the incoming stream are seen to correlate with the sensory network. These findings support a view of the lateral line as a "hydrodynamic antenna" that is configured to retrieve flow signals and also suggest a physical explanation for the nearly universal sensory layout across diverse species.

  20. An Idea of Staged and Large Velocity Differential Secondary Air for Waterwall Erosion Protection and Oxygen Complementarity

    NASA Astrophysics Data System (ADS)

    Liu, B. Q.; Zhang, X. H.

    A successful design of circulating fluidized bed (CFB) boiler should have the highest combustion efficiency, economic operation, and optimum availability. There is a coupled phenomenon of an oxygen lean zone existing in the CFB boiler furnace which depresses combustion efficiency and particle (group) falling down faster and faster when it falls along the waterwall, abrading the tube metal effectively. A new secondary air design for the oxygen lean zone and erosion protection is conceived by using staged and large velocity differential secondary air. For example, a part of concentrate supplied secondary air has been divided into two parts: a low velocity part and a high velocity part. The low velocity part is used for rigid gas layer to reduce the particle falling velocity, and the high velocity part is used for oxygen supply. It is believed that 40˜6Om/s projecting air velocity could send new oxygen to at least half furnace depth in a short projecting lift as shown in calculation. In another view point, operational superficial gas velocity has an obvious effect on waterwall metal erosion, with a lower operation velocity having lower erosion.